diff options
Diffstat (limited to 'lib/kernel/doc/src')
30 files changed, 4621 insertions, 439 deletions
diff --git a/lib/kernel/doc/src/.gitignore b/lib/kernel/doc/src/.gitignore new file mode 100644 index 0000000000..c2813ac866 --- /dev/null +++ b/lib/kernel/doc/src/.gitignore @@ -0,0 +1 @@ +*.eps
\ No newline at end of file diff --git a/lib/kernel/doc/src/Makefile b/lib/kernel/doc/src/Makefile index 0759f362d4..f8867ccf25 100644 --- a/lib/kernel/doc/src/Makefile +++ b/lib/kernel/doc/src/Makefile @@ -1,7 +1,7 @@ # # %CopyrightBegin% # -# Copyright Ericsson AB 1997-2016. All Rights Reserved. +# Copyright Ericsson AB 1997-2018. All Rights Reserved. # # Licensed under the Apache License, Version 2.0 (the "License"); # you may not use this file except in compliance with the License. @@ -42,6 +42,7 @@ XML_REF3_FILES = application.xml \ disk_log.xml \ erl_boot_server.xml \ erl_ddll.xml \ + erl_epmd.xml \ erl_prim_loader_stub.xml \ erlang_stub.xml \ error_handler.xml \ @@ -56,6 +57,11 @@ XML_REF3_FILES = application.xml \ inet.xml \ inet_res.xml \ init_stub.xml \ + logger.xml \ + logger_std_h.xml \ + logger_disk_log_h.xml \ + logger_filters.xml \ + logger_formatter.xml \ net_adm.xml \ net_kernel.xml \ os.xml \ @@ -70,11 +76,18 @@ XML_REF4_FILES = app.xml config.xml XML_REF6_FILES = kernel_app.xml -XML_PART_FILES = -XML_CHAPTER_FILES = notes.xml +XML_PART_FILES = part.xml +XML_CHAPTER_FILES = \ + notes.xml \ + introduction_chapter.xml \ + logger_chapter.xml BOOK_FILES = book.xml +# The .png file is generated from a .dia file with target 'update_png' +IMAGE_FILES = \ + logger_arch.png + XML_FILES = \ $(BOOK_FILES) $(XML_CHAPTER_FILES) \ $(XML_PART_FILES) $(XML_REF3_FILES) $(XML_REF4_FILES)\ @@ -100,6 +113,17 @@ SPECS_FILES = $(XML_REF3_FILES:%.xml=$(SPECDIR)/specs_%.xml) TOP_SPECS_FILE = specs.xml # ---------------------------------------------------- +# FIGURES +# ---------------------------------------------------- +# In order to update the figures you have to have both dia +# and imagemagick installed. +# The generated .png file must be committed. + +update_png: + dia --export=logger_arch.eps logger_arch.dia + convert logger_arch.eps -resize 65% logger_arch.png + +# ---------------------------------------------------- # FLAGS # ---------------------------------------------------- XML_FLAGS += @@ -111,7 +135,7 @@ SPECS_FLAGS = -I../../include # ---------------------------------------------------- # Targets # ---------------------------------------------------- -$(HTMLDIR)/%.gif: %.gif +$(HTMLDIR)/%: % $(INSTALL_DATA) $< $@ docs: man pdf html @@ -120,33 +144,35 @@ $(TOP_PDF_FILE): $(XML_FILES) pdf: $(TOP_PDF_FILE) -html: gifs $(HTML_REF_MAN_FILE) +html: images $(HTML_REF_MAN_FILE) man: $(MAN3_FILES) $(MAN4_FILES) $(MAN6_FILES) -gifs: $(GIF_FILES:%=$(HTMLDIR)/%) +images: $(IMAGE_FILES:%=$(HTMLDIR)/%) + debug opt: clean clean_docs: rm -rf $(HTMLDIR)/* + rm -rf $(XMLDIR) rm -f $(MAN3DIR)/* rm -f $(MAN4DIR)/* rm -f $(MAN6DIR)/* rm -f $(TOP_PDF_FILE) $(TOP_PDF_FILE:%.pdf=%.fo) rm -f $(SPECDIR)/* - rm -f errs core *~ + rm -f errs core *~ *.eps $(SPECDIR)/specs_erl_prim_loader_stub.xml: - escript $(SPECS_EXTRACTOR) $(SPECS_FLAGS) \ + $(gen_verbose)escript $(SPECS_EXTRACTOR) $(SPECS_FLAGS) \ -o$(dir $@) -module erl_prim_loader_stub $(SPECDIR)/specs_erlang_stub.xml: - escript $(SPECS_EXTRACTOR) $(SPECS_FLAGS) \ + $(gen_verbose)escript $(SPECS_EXTRACTOR) $(SPECS_FLAGS) \ -o$(dir $@) -module erlang_stub $(SPECDIR)/specs_init_stub.xml: - escript $(SPECS_EXTRACTOR) $(SPECS_FLAGS) \ + $(gen_verbose)escript $(SPECS_EXTRACTOR) $(SPECS_FLAGS) \ -o$(dir $@) -module init_stub $(SPECDIR)/specs_zlib_stub.xml: - escript $(SPECS_EXTRACTOR) $(SPECS_FLAGS) \ + $(gen_verbose)escript $(SPECS_EXTRACTOR) $(SPECS_FLAGS) \ -o$(dir $@) -module zlib_stub # ---------------------------------------------------- diff --git a/lib/kernel/doc/src/application.xml b/lib/kernel/doc/src/application.xml index 886286b76d..38c7b5acf1 100644 --- a/lib/kernel/doc/src/application.xml +++ b/lib/kernel/doc/src/application.xml @@ -4,7 +4,7 @@ <erlref> <header> <copyright> - <year>1996</year><year>2016</year> + <year>1996</year><year>2018</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> @@ -318,8 +318,13 @@ Nodes = [cp1@cave, {cp2@cave, cp3@cave}]</code> <c>{error,{not_started,App}}</c> is returned, where <c>App</c> is the name of the missing application.</p> <p>The application controller then creates an <em>application master</em> - for the application. The application master is - the group leader of all the processes in the application. + for the application. The application master becomes the + group leader of all the processes in the application. I/O is + forwarded to the previous group leader, though, this is just + a way to identify processes that belong to the application. + Used for example to find itself from any process, or, + reciprocally, to kill them all when it terminates.</p> + <p> The application master starts the application by calling the application callback function <c>Module:start/2</c> as defined by the application specification key <c>mod</c>.</p> @@ -608,4 +613,3 @@ Nodes = [cp1@cave, {cp2@cave, cp3@cave}]</code> <seealso marker="app">app(4)</seealso></p> </section> </erlref> - diff --git a/lib/kernel/doc/src/book.xml b/lib/kernel/doc/src/book.xml index 81a87d126d..4b3573b9fe 100644 --- a/lib/kernel/doc/src/book.xml +++ b/lib/kernel/doc/src/book.xml @@ -4,7 +4,7 @@ <book xmlns:xi="http://www.w3.org/2001/XInclude"> <header titlestyle="normal"> <copyright> - <year>1997</year><year>2016</year> + <year>1997</year><year>2018</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> @@ -34,6 +34,9 @@ <preamble> <contents level="2"></contents> </preamble> + <parts lift="yes"> + <xi:include href="part.xml"/> + </parts> <applications> <xi:include href="ref_man.xml"/> </applications> diff --git a/lib/kernel/doc/src/code.xml b/lib/kernel/doc/src/code.xml index c94f612c01..aff3e8133c 100644 --- a/lib/kernel/doc/src/code.xml +++ b/lib/kernel/doc/src/code.xml @@ -4,7 +4,7 @@ <erlref> <header> <copyright> - <year>1996</year><year>2017</year> + <year>1996</year><year>2018</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> @@ -34,26 +34,28 @@ <p>This module contains the interface to the Erlang <em>code server</em>, which deals with the loading of compiled code into a running Erlang runtime system.</p> - <p>The runtime system can be started in <em>embedded</em> or - <em>interactive</em> mode. Which one is decided by command-line + <p>The runtime system can be started in <em>interactive</em> or + <em>embedded</em> mode. Which one is decided by the command-line flag <c>-mode</c>:</p> <pre> % <input>erl -mode interactive</input></pre> <p>The modes are as follows:</p> <list type="bulleted"> <item> - <p>In embedded mode, all code is loaded during system startup - according to the boot script. (Code can also be loaded later - by explicitly ordering the code server to do so).</p> - </item> - <item> <p>In interactive mode, which is default, only some code is loaded - during system startup, basically the modules needed by the runtime + during system startup, basically the modules needed by the runtime system. Other code is dynamically loaded when first referenced. When a call to a function in a certain module is made, and the module is not loaded, the code server searches for and tries to load the module.</p> </item> + <item> + <p>In embedded mode, modules are not auto loaded. Trying to use + a module that has not been loaded results in an error. This mode is + recommended when the boot script loads all modules, as it is + typically done in OTP releases. (Code can still be loaded later + by explicitly ordering the code server to do so).</p> + </item> </list> <p>To prevent accidentally reloading of modules affecting the Erlang runtime system, directories <c>kernel</c>, <c>stdlib</c>, diff --git a/lib/kernel/doc/src/config.xml b/lib/kernel/doc/src/config.xml index fdb2d29f63..714af93f4d 100644 --- a/lib/kernel/doc/src/config.xml +++ b/lib/kernel/doc/src/config.xml @@ -4,7 +4,7 @@ <fileref> <header> <copyright> - <year>1997</year><year>2017</year> + <year>1997</year><year>2018</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> @@ -37,10 +37,10 @@ data in the system configuration file <c>Name.config</c>.</p> <p>Configuration parameter values in the configuration file override the values in the application resource files (see - <seealso marker="app"><c>app(4)</c></seealso>. + <seealso marker="app"><c>app(4)</c></seealso>). The values in the configuration file can be overridden by command-line flags (see - <seealso marker="erts:erl"><c>erts:erl(1)</c></seealso>.</p> + <seealso marker="erts:erl"><c>erts:erl(1)</c></seealso>).</p> <p>The value of a configuration parameter is retrieved by calling <c>application:get_env/1,2</c>.</p> </description> @@ -86,8 +86,13 @@ <tag><c>File = string()</c></tag> <item>Name of another <c>.config</c> file. Extension <c>.config</c> can be omitted. It is - recommended to use absolute paths. A relative path is - relative the current working directory of the emulator.</item> + recommended to use absolute paths. If a relative path is used, + <c>File</c> is searched, first, relative from <c>sys.config</c> directory, then relative + to the current working directory of the emulator, for backward compatibility. + This allow to use a <c>sys.config</c> pointing out other <c>.config</c> files in a release + or in a node started manually using <c>-config ...</c> with same result whatever + the current working directory. + </item> </taglist> <p>When traversing the contents of <c>sys.config</c> and a filename is encountered, its contents are read and merged with the result diff --git a/lib/kernel/doc/src/erl_epmd.xml b/lib/kernel/doc/src/erl_epmd.xml new file mode 100644 index 0000000000..8b076cd2d7 --- /dev/null +++ b/lib/kernel/doc/src/erl_epmd.xml @@ -0,0 +1,104 @@ +<?xml version="1.0" encoding="utf-8" ?> +<!DOCTYPE erlref SYSTEM "erlref.dtd"> + +<erlref> + <header> + <copyright> + <year>2018</year><year>2018</year> + <holder>Ericsson AB. All Rights Reserved.</holder> + </copyright> + <legalnotice> + Licensed under the Apache License, Version 2.0 (the "License"); + you may not use this file except in compliance with the License. + You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + + Unless required by applicable law or agreed to in writing, software + distributed under the License is distributed on an "AS IS" BASIS, + WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + See the License for the specific language governing permissions and + limitations under the License. + + </legalnotice> + + <title>erl_epmd</title> + <prepared>Timmo Verlaan</prepared> + <docno>1</docno> + <date>2018-02-19</date> + <rev>A</rev> + </header> + <module>erl_epmd</module> + <modulesummary> + Erlang interface towards epmd + </modulesummary> + <description> + <p>This module communicates with the EPMD daemon, see <seealso + marker="erts:epmd">epmd</seealso>. To implement your own epmd module please + see <seealso marker="erts:alt_disco">ERTS User's Guide: How to Implement an + Alternative Service Discovery for Erlang Distribution</seealso></p> + </description> + + <funcs> + <func> + <name name="start_link" arity="0"/> + <fsummary>Callback for erl_distribution supervisor.</fsummary> + <desc> + <p>This function is invoked as this module is added as a child of the + <c>erl_distribution</c> supervisor.</p> + </desc> + </func> + + <func> + <name name="register_node" arity="2"/> + <name name="register_node" arity="3"/> + <fsummary>Registers the node with <c>epmd</c>.</fsummary> + <desc> + <p>Registers the node with <c>epmd</c> and tells epmd what port will be + used for the current node. It returns a creation number. This number is + incremented on each register to help with identifying if a node is + reconnecting to epmd.</p> + </desc> + </func> + + <func> + <name name="port_please" arity="2"/> + <name name="port_please" arity="3"/> + <fsummary>Returns the port number for a given node.</fsummary> + <desc> + <p>Requests the distribution port for the given node of an EPMD + instance. Together with the port it returns a distribution protocol + version which has been 5 since Erlang/OTP R6.</p> + </desc> + </func> + + <func> + <name name="address_please" arity="3"/> + <fsummary>Returns address and port.</fsummary> + <desc> + <p>Called by the distribution module. Resolves the <c>Host</c> to an IP + address.</p> + <p>Another epmd module may return port and distribution protocol version + as well.</p> + </desc> + </func> + + <func> + <name name="names" arity="1"/> + <fsummary>Names of Erlang nodes at a host.</fsummary> + <desc> + <p>Called by <seealso marker="net_adm"><c>net_adm:names/0</c></seealso>. + <c>Host</c> defaults to the localhost. Returns the names and associated + port numbers of the Erlang nodes that <c>epmd</c> registered at the + specified host. Returns <c>{error, address}</c> if <c>epmd</c> is not + operational.</p> + <p><em>Example:</em></p> + <pre> +(arne@dunn)1> <input>erl_epmd:names(localhost).</input> +{ok,[{"arne",40262}]}</pre> + </desc> + </func> + </funcs> + +</erlref> + diff --git a/lib/kernel/doc/src/error_logger.xml b/lib/kernel/doc/src/error_logger.xml index 91bf57cb91..c3d68fd79f 100644 --- a/lib/kernel/doc/src/error_logger.xml +++ b/lib/kernel/doc/src/error_logger.xml @@ -4,7 +4,7 @@ <erlref> <header> <copyright> - <year>1996</year><year>2017</year> + <year>1996</year><year>2018</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> @@ -31,36 +31,37 @@ <module>error_logger</module> <modulesummary>Erlang error logger.</modulesummary> <description> + + <note> + <p>In Erlang/OTP 21.0, a new API for logging was added. The + old <c>error_logger</c> module can still be used by legacy + code, but log events are redirected to the new Logger API. New + code should use the Logger API directly.</p> + <p><c>error_logger</c> is no longer started by default, but is + automatically started when an event handler is added + with <c>error_logger:add_report_handler/1,2</c>. The <c>error_logger</c> + module is then also added as a handler to the new logger.</p> + <p>See <seealso marker="logger"><c>logger(3)</c></seealso> and + the <seealso marker="logger_chapter">Logging</seealso> chapter + in the User's Guide for more information.</p> + </note> + <p>The Erlang <em>error logger</em> is an event manager (see <seealso marker="doc/design_principles:des_princ">OTP Design Principles</seealso> and <seealso marker="stdlib:gen_event"><c>gen_event(3)</c></seealso>), - registered as <c>error_logger</c>. Errors, warnings, and info events - are sent to the error logger from the Erlang runtime system and - the different Erlang/OTP applications. The events are, by default, - logged to the terminal. Notice that an event from a process <c>P</c> is - logged at the node of the group leader of <c>P</c>. This means - that log output is directed to the node from which a process was - created, which not necessarily is the same node as where it is - executing.</p> - <p>Initially, <c>error_logger</c> has only a primitive event - handler, which buffers and prints the raw event messages. During - system startup, the Kernel application replaces this with a - <em>standard event handler</em>, by default one that writes - nicely formatted output to the terminal. Kernel can also be - configured so that events are logged to a file instead, or not logged at all, - see <seealso marker="kernel_app"><c>kernel(6)</c></seealso>.</p> - <p>Also the SASL application, if started, adds its own event - handler, which by default writes supervisor, crash, and progress - reports to the terminal. See - <seealso marker="sasl:sasl_app"><c>sasl(6)</c></seealso>.</p> - <p>It is recommended that user-defined applications report - errors through the error logger to get uniform reports. - User-defined event handlers can be added to handle application-specific - events, see - <seealso marker="#add_report_handler/1"><c>add_report_handler/1,2</c></seealso>. - Also, a useful event handler is provided in STDLIB for multi-file - logging of events, see - <seealso marker="stdlib:log_mf_h"><c>log_mf_h(3)</c></seealso>.</p> + registered as <c>error_logger</c>.</p> + <p>Error logger is no longer started by default, but is + automatically started when an event handler is added + with <seealso marker="#add_report_handler/1"> + <c>add_report_handler/1,2</c></seealso>. The <c>error_logger</c> + module is then also added as a handler to the new logger, + causing log events to be forwarded from logger to error logger, + and consequently to all installed error logger event + handlers.</p> + <p>User-defined event handlers can be added to handle application-specific + events.</p> + <p>Existing event handlers provided by STDLIB and SASL are still + available, but are no longer used by OTP.</p> <p>Warning events were introduced in Erlang/OTP R9C and are enabled by default as from Erlang/OTP 18.0. To retain backwards compatibility with existing user-defined event handlers, the warning events can be @@ -89,6 +90,9 @@ The function returns <c>ok</c> if successful.</p> <p>The event handler must be able to handle the events in this module, see section <seealso marker="#events">Events</seealso>.</p> + <p>The first time this function is called, + <c>error_logger</c> is added as a Logger handler, and + the <c>error_logger</c> process is started.</p> </desc> </func> <func> @@ -98,37 +102,40 @@ <p>Deletes an event handler from the error logger by calling <c>gen_event:delete_handler(error_logger, <anno>Handler</anno>, [])</c>, see <seealso marker="stdlib:gen_event"><c>gen_event(3)</c></seealso>.</p> + <p>If no more event handlers exist after the deletion, + <c>error_logger</c> is removed as a Logger handler, and + the <c>error_logger</c> process is stopped.</p> </desc> </func> <func> <name name="error_msg" arity="1"/> <name name="error_msg" arity="2"/> <name name="format" arity="2"/> - <fsummary>Send a standard error event to the error logger.</fsummary> + <fsummary>Log a standard error event.</fsummary> <desc> - <p>Sends a standard error event to the error logger. - The <c><anno>Format</anno></c> and <c><anno>Data</anno></c> arguments - are the same as the arguments of + <p>Log a standard error event. The <c><anno>Format</anno></c> + and <c><anno>Data</anno></c> arguments are the same as the + arguments of <seealso marker="stdlib:io#format/2"><c>io:format/2</c></seealso> - in STDLIB. - The event is handled by the standard event handler.</p> + in STDLIB.</p> + <p>Error logger forwards the event to Logger, including + metadata that allows backwards compatibility with legacy + error logger event handlers.</p> + <p>The event is handled by the default Logger handler.</p> + <p>These functions are kept for backwards compatibility and + must not be used by new code. Use the <seealso marker="logger#macros"> + <c>?LOG_ERROR</c></seealso> macro or + <seealso marker="logger#error-1"><c>logger:error/1,2,3</c></seealso> + instead.</p> <p><em>Example:</em></p> <pre> -1> <input>error_logger:error_msg("An error occurred in ~p~n", [a_module]).</input> - -=ERROR REPORT==== 11-Aug-2005::14:03:19 === +1> <input>error_logger:error_msg("An error occurred in ~p", [a_module]).</input> +=ERROR REPORT==== 22-May-2018::11:18:43.376917 === An error occurred in a_module ok</pre> <warning> - <p>If called with bad arguments, this function can crash - the standard event handler, meaning no further events are - logged. When in doubt, use - <seealso marker="#error_report/1"><c>error_report/1</c></seealso> - instead.</p> - </warning> - <warning> <p>If the Unicode translation modifier (<c>t</c>) is used in - the format string, all error handlers must ensure that the + the format string, all event handlers must ensure that the formatted output is correctly encoded for the I/O device.</p> </warning> @@ -136,36 +143,51 @@ ok</pre> </func> <func> <name name="error_report" arity="1"/> - <fsummary>Send a standard error report event to the error logger.</fsummary> + <fsummary>Log a standard error event.</fsummary> <desc> - <p>Sends a standard error report event to the error logger. - The event is handled by the standard event handler.</p> + <p>Log a standard error event. Error logger forwards the event + to Logger, including metadata that allows backwards + compatibility with legacy error logger event handlers.</p> + <p>The event is handled by the default Logger handler.</p> + <p>This functions is kept for backwards compatibility and + must not be used by new code. Use the <seealso marker="logger#macros"> + <c>?LOG_ERROR</c></seealso> macro or + <seealso marker="logger#error-1"><c>logger:error/1,2,3</c></seealso> + instead.</p> <p><em>Example:</em></p> <pre> 2> <input>error_logger:error_report([{tag1,data1},a_term,{tag2,data}]).</input> - -=ERROR REPORT==== 11-Aug-2005::13:45:41 === +=ERROR REPORT==== 22-May-2018::11:24:23.699306 === tag1: data1 a_term tag2: data ok 3> <input>error_logger:error_report("Serious error in my module").</input> - -=ERROR REPORT==== 11-Aug-2005::13:45:49 === +=ERROR REPORT==== 22-May-2018::11:24:45.972445 === Serious error in my module ok</pre> </desc> </func> <func> <name name="error_report" arity="2"/> - <fsummary>Send a user-defined error report event to the error logger.</fsummary> + <fsummary>Log a user-defined error event.</fsummary> <desc> - <p>Sends a user-defined error report event to the error logger. - An event handler to handle the event is supposed to have been - added. The event is ignored by the standard event handler.</p> + <p>Log a user-defined error event. Error logger forwards the + event to Logger, including metadata that allows backwards + compatibility with legacy error logger event handlers.</p> + <p>Error logger also adds a <c>domain</c> field with + value <c>[<anno>Type</anno>]</c> to this event's metadata, + causing the filters of the default Logger handler to discard + the event. A different Logger handler, or an error logger + event handler, must be added to handle this event.</p> <p>It is recommended that <c><anno>Report</anno></c> follows the same structure as for <seealso marker="#error_report/1"><c>error_report/1</c></seealso>.</p> + <p>This functions is kept for backwards compatibility and + must not be used by new code. Use the <seealso marker="logger#macros"> + <c>?LOG_ERROR</c></seealso> macro or + <seealso marker="logger#error-1"><c>logger:error/1,2,3</c></seealso> + instead.</p> </desc> </func> <func> @@ -174,38 +196,48 @@ ok</pre> <c>error_logger_format_depth</c>.</fsummary> <desc> <p>Returns <c>max(10, Depth)</c>, where <c>Depth</c> is the - value of - <seealso marker="kernel:kernel_app#error_logger_format_depth"> - error_logger_format_depth</seealso> + value of <c>error_logger_format_depth</c> in the Kernel application, if Depth is an integer. Otherwise, <c>unlimited</c> is returned.</p> + <note> + <p>The <c>error_logger_format_depth</c> variable + is <seealso marker="kernel_app#deprecated-configuration-parameters"> + deprecated</seealso> since + the <seealso marker="logger">Logger API</seealso> was + introduced in Erlang/OTP 21.0. The variable, and this + function, are kept for backwards compatibility since they + still might be used by legacy report handlers.</p> + </note> </desc> </func> <func> <name name="info_msg" arity="1"/> <name name="info_msg" arity="2"/> - <fsummary>Send a standard information event to the error logger.</fsummary> + <fsummary>Log a standard information event.</fsummary> <desc> - <p>Sends a standard information event to the error logger. - The <c><anno>Format</anno></c> and <c><anno>Data</anno></c> arguments - are the same as the arguments of + <p>Log a standard information event. The <c><anno>Format</anno></c> + and <c><anno>Data</anno></c> arguments are the same as the + arguments of <seealso marker="stdlib:io#format/2"><c>io:format/2</c></seealso> - in STDLIB. The event is handled by the standard event handler.</p> + in STDLIB.</p> + <p>Error logger forwards the event to Logger, including + metadata that allows backwards compatibility with legacy + error logger event handlers.</p> + <p>The event is handled by the default Logger handler.</p> + <p>These functions are kept for backwards compatibility and + must not be used by new code. Use the <seealso marker="logger#macros"> + <c>?LOG_INFO</c></seealso> macro or + <seealso marker="logger#info-1"><c>logger:info/1,2,3</c></seealso> + instead.</p> <p><em>Example:</em></p> <pre> -1> <input>error_logger:info_msg("Something happened in ~p~n", [a_module]).</input> - -=INFO REPORT==== 11-Aug-2005::14:06:15 === +1> <input>error_logger:info_msg("Something happened in ~p", [a_module]).</input> +=INFO REPORT==== 22-May-2018::12:03:32.612462 === Something happened in a_module ok</pre> <warning> - <p>If called with bad arguments, this function can crash - the standard event handler, meaning no further events are - logged. When in doubt, use <c>info_report/1</c> instead.</p> - </warning> - <warning> <p>If the Unicode translation modifier (<c>t</c>) is used in - the format string, all error handlers must ensure that the + the format string, all event handlers must ensure that the formatted output is correctly encoded for the I/O device.</p> </warning> @@ -213,37 +245,52 @@ ok</pre> </func> <func> <name name="info_report" arity="1"/> - <fsummary>Send a standard information report event to the error logger.</fsummary> + <fsummary>Log a standard information event.</fsummary> <desc> - <p>Sends a standard information report event to the error - logger. The event is handled by the standard event handler.</p> + <p>Log a standard information event. Error logger forwards the + event to Logger, including metadata that allows backwards + compatibility with legacy error logger event handlers.</p> + <p>The event is handled by the default Logger handler.</p> + <p>This functions is kept for backwards compatibility and + must not be used by new code. Use the <seealso marker="logger#macros"> + <c>?LOG_INFO</c></seealso> macro or + <seealso marker="logger#info-1"><c>logger:info/1,2,3</c></seealso> + instead.</p> <p><em>Example:</em></p> <pre> 2> <input>error_logger:info_report([{tag1,data1},a_term,{tag2,data}]).</input> - -=INFO REPORT==== 11-Aug-2005::13:55:09 === +=INFO REPORT==== 22-May-2018::12:06:35.994440 === tag1: data1 a_term tag2: data ok 3> <input>error_logger:info_report("Something strange happened").</input> - -=INFO REPORT==== 11-Aug-2005::13:55:36 === +=INFO REPORT==== 22-May-2018::12:06:49.066872 === Something strange happened ok</pre> </desc> </func> <func> <name name="info_report" arity="2"/> - <fsummary>Send a user-defined information report event to the error logger.</fsummary> + <fsummary>Log a user-defined information event.</fsummary> <desc> - <p>Sends a user-defined information report event to the error - logger. An event handler to handle the event is supposed to - have been added. The event is ignored by the standard event - handler.</p> + <p>Log a user-defined information event. Error logger forwards + the event to Logger, including metadata that allows + backwards compatibility with legacy error logger event + handlers.</p> + <p>Error logger also adds a <c>domain</c> field with + value <c>[<anno>Type</anno>]</c> to this event's metadata, + causing the filters of the default Logger handler to discard + the event. A different Logger handler, or an error logger + event handler, must be added to handle this event.</p> <p>It is recommended that <c><anno>Report</anno></c> follows the same structure as for <seealso marker="#info_report/1"><c>info_report/1</c></seealso>.</p> + <p>This functions is kept for backwards compatibility and + must not be used by new code. Use the <seealso marker="logger#macros"> + <c>?LOG_INFO</c></seealso> macro or + <seealso marker="logger#info-1"><c>logger:info/1,2,3</c></seealso> + instead.</p> </desc> </func> <func> @@ -258,14 +305,22 @@ ok</pre> <type name="open_error"/> <desc> <p>Enables or disables printout of standard events to a file.</p> - <p>This is done by adding or deleting the standard event handler - for output to file. Thus, calling this function overrides - the value of the Kernel <c>error_logger</c> configuration - parameter.</p> - <p>Enabling file logging can be used together with calling - <c>tty(false)</c>, to have a silent system where - all standard events are logged to a file only. - Only one log file can be active at a time.</p> + <p>This is done by adding or deleting + the <c>error_logger_file_h</c> event handler, and thus + indirectly adding <c>error_logger</c> as a Logger + handler.</p> + <p>Notice that this function does not manipulate the Logger + configuration directly, meaning that if the default Logger + handler is already logging to a file, this function can + potentially cause logging to a second file.</p> + <p>This function is useful as a shortcut during development + and testing, but must not be used in a production + system. See + section <seealso marker="logger_chapter">Logging</seealso> + in the Kernel User's Guide, and + the <seealso marker="logger"><c>logger(3)</c></seealso> + manual page for information about how to configure Logger + for live systems.</p> <p><c>Request</c> is one of the following:</p> <taglist> <tag><c>{open, <anno>Filename</anno>}</c></tag> @@ -297,9 +352,14 @@ ok</pre> <p>Enables (<c><anno>Flag</anno> == true</c>) or disables (<c><anno>Flag</anno> == false</c>) printout of standard events to the terminal.</p> - <p>This is done by adding or deleting the standard event handler - for output to the terminal. Thus, calling this function overrides - the value of the Kernel <c>error_logger</c> configuration parameter.</p> + <p>This is done by manipulating the Logger configuration. The + function is useful as a shortcut during development and + testing, but must not be used in a production system. See + section <seealso marker="logger_chapter">Logging</seealso> + in the Kernel User's Guide, and + the <seealso marker="logger"><c>logger(3)</c></seealso> + manual page for information about how to configure Logger + for live systems.</p> </desc> </func> <func> @@ -342,24 +402,27 @@ ok</pre> <func> <name name="warning_msg" arity="1"/> <name name="warning_msg" arity="2"/> - <fsummary>Send a standard warning event to the error logger.</fsummary> + <fsummary>Log a standard warning event.</fsummary> <desc> - <p>Sends a standard warning event to the error logger. - The <c><anno>Format</anno></c> and <c><anno>Data</anno></c> arguments - are the same as the arguments of + <p>Log a standard warning event. The <c><anno>Format</anno></c> + and <c><anno>Data</anno></c> arguments are the same as the + arguments of <seealso marker="stdlib:io#format/2"><c>io:format/2</c></seealso> - in STDLIB. - The event is handled by the standard event handler. It is tagged - as an error, warning, or info, see + in STDLIB.</p> + <p>Error logger forwards the event to Logger, including + metadata that allows backwards compatibility with legacy + error logger event handlers.</p> + <p>The event is handled by the default Logger handler. The log + level can be changed to error or info, see <seealso marker="#warning_map/0"><c>warning_map/0</c></seealso>.</p> - <warning> - <p>If called with bad arguments, this function can crash - the standard event handler, meaning no further events are - logged. When in doubt, use <c>warning_report/1</c> instead.</p> - </warning> + <p>These functions are kept for backwards compatibility and + must not be used by new code. Use the <seealso marker="logger#macros"> + <c>?LOG_WARNING</c></seealso> macro or + <seealso marker="logger#warning-1"><c>logger:warning/1,2,3</c></seealso> + instead.</p> <warning> <p>If the Unicode translation modifier (<c>t</c>) is used in - the format string, all error handlers must ensure that the + the format string, all event handlers must ensure that the formatted output is correctly encoded for the I/O device.</p> </warning> @@ -367,24 +430,43 @@ ok</pre> </func> <func> <name name="warning_report" arity="1"/> - <fsummary>Send a standard warning report event to the error logger.</fsummary> + <fsummary>Log a standard warning event.</fsummary> <desc> - <p>Sends a standard warning report event to the error logger. - The event is handled by the standard event handler. It is - tagged as an error, warning, or info, see + <p>Log a standard warning event. Error logger forwards the event + to Logger, including metadata that allows backwards + compatibility with legacy error logger event handlers.</p> + <p>The event is handled by the default Logger handler. The log + level can be changed to error or info, see <seealso marker="#warning_map/0"><c>warning_map/0</c></seealso>.</p> + <p>This functions is kept for backwards compatibility and + must not be used by new code. Use the <seealso marker="logger#macros"> + <c>?LOG_WARNING</c></seealso> macro or + <seealso marker="logger#warning-1"><c>logger:warning/1,2,3</c></seealso> + instead.</p> </desc> </func> <func> <name name="warning_report" arity="2"/> - <fsummary>Send a user-defined warning report event to the error logger.</fsummary> + <fsummary>Log a user-defined warning event.</fsummary> <desc> - <p>Sends a user-defined warning report event to the error - logger. An event handler to handle the event is supposed to - have been added. The event is ignored by the standard event - handler. It is tagged as an error, warning, or info, - depending on the value of + <p>Log a user-defined warning event. Error logger forwards the + event to Logger, including metadata that allows backwards + compatibility with legacy error logger event handlers.</p> + <p>Error logger also adds a <c>domain</c> field with + value <c>[<anno>Type</anno>]</c> to this event's metadata, + causing the filters of the default Logger handler to discard + the event. A different Logger handler, or an error logger + event handler, must be added to handle this event.</p> + <p>The log level can be changed to error or info, see <seealso marker="#warning_map/0"><c>warning_map/0</c></seealso>.</p> + <p>It is recommended that <c><anno>Report</anno></c> follows the same + structure as for + <seealso marker="#warning_report/1"><c>warning_report/1</c></seealso>.</p> + <p>This functions is kept for backwards compatibility and + must not be used by new code. Use the <seealso marker="logger#macros"> + <c>?LOG_WARNING</c></seealso> macro or + <seealso marker="logger#warning-1"><c>logger:warning/1,2,3</c></seealso> + instead.</p> </desc> </func> </funcs> @@ -448,8 +530,9 @@ ok</pre> <section> <title>See Also</title> <p><seealso marker="stdlib:gen_event"><c>gen_event(3)</c></seealso>, - <seealso marker="stdlib:log_mf_h"><c>log_mf_h(3)</c></seealso> - <seealso marker="kernel_app"><c>kernel(6)</c></seealso> + <seealso marker="kernel:logger"><c>logger(3)</c></seealso>, + <seealso marker="stdlib:log_mf_h"><c>log_mf_h(3)</c></seealso>, + <seealso marker="kernel_app"><c>kernel(6)</c></seealso>, <seealso marker="sasl:sasl_app"><c>sasl(6)</c></seealso></p> </section> </erlref> diff --git a/lib/kernel/doc/src/file.xml b/lib/kernel/doc/src/file.xml index b674b3ca93..9acaf6b41e 100644 --- a/lib/kernel/doc/src/file.xml +++ b/lib/kernel/doc/src/file.xml @@ -4,7 +4,7 @@ <erlref> <header> <copyright> - <year>1996</year><year>2016</year> + <year>1996</year><year>2018</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> @@ -33,15 +33,18 @@ <description> <p>This module provides an interface to the file system.</p> - <p>On operating systems with thread support, - file operations can be performed in threads of their own, allowing - other Erlang processes to continue executing in parallel with - the file operations. See command-line flag - <c>+A</c> in <seealso marker="erts:erl"><c>erl(1)</c></seealso>.</p> + <warning> + <p>File operations are only guaranteed to appear atomic when going + through the same file server. A NIF or other OS process may observe + intermediate steps on certain operations on some operating systems, + eg. renaming an existing file on Windows, or + <seealso marker="#write_file_info/2"><c>write_file_info/2</c> + </seealso> on any OS at the time of writing.</p> + </warning> <p>Regarding filename encoding, the Erlang VM can operate in two modes. The current mode can be queried using function - <seealso marker="#native_name_encoding"><c>native_name_encoding/0</c></seealso>. + <seealso marker="#native_name_encoding/0"><c>native_name_encoding/0</c></seealso>. It returns <c>latin1</c> or <c>utf8</c>.</p> <p>In <c>latin1</c> mode, the Erlang VM does not change the @@ -59,7 +62,7 @@ terminal supports UTF-8, otherwise <c>latin1</c>. The default can be overridden using <c>+fnl</c> (to force <c>latin1</c> mode) or <c>+fnu</c> (to force <c>utf8</c> mode) when starting - <seealso marker="erts:erl"><c>erts:erl</c></seealso>.</p> + <seealso marker="erts:erl"><c>erl</c></seealso>.</p> <p>On operating systems with transparent naming, files can be inconsistently named, for example, some files are encoded in UTF-8 while @@ -81,6 +84,16 @@ <p>See also section <seealso marker="stdlib:unicode_usage#notes-about-raw-filenames">Notes About Raw Filenames</seealso> in the STDLIB User's Guide.</p> + <note><p> + File operations used to accept filenames containing + null characters (integer value zero). This caused + the name to be truncated and in some cases arguments + to primitive operations to be mixed up. Filenames + containing null characters inside the filename + are now <em>rejected</em> and will cause primitive + file operations fail. + </p></note> + </description> <datatypes> @@ -96,9 +109,21 @@ </datatype> <datatype> <name name="filename"/> + <desc> + <p> + See also the documentation of the + <seealso marker="#type-name_all"><c>name_all()</c></seealso> type. + </p> + </desc> </datatype> <datatype> <name name="filename_all"/> + <desc> + <p> + See also the documentation of the + <seealso marker="#type-name_all"><c>name_all()</c></seealso> type. + </p> + </desc> </datatype> <datatype> <name name="io_device"/> @@ -112,21 +137,23 @@ <name name="name"/> <desc> <p>If VM is in Unicode filename mode, <c>string()</c> and <c>char()</c> - are allowed to be > 255. + are allowed to be > 255. See also the documentation of the + <seealso marker="#type-name_all"><c>name_all()</c></seealso> type. </p> </desc> </datatype> <datatype> <name name="name_all"/> <desc> - <p>If VM is in Unicode filename mode, <c>string()</c> and <c>char()</c> + <p>If VM is in Unicode filename mode, characters are allowed to be > 255. <c><anno>RawFilename</anno></c> is a filename not subject to Unicode translation, meaning that it can contain characters not conforming to the Unicode encoding expected from the file system (that is, non-UTF-8 characters although the VM is started - in Unicode filename mode). + in Unicode filename mode). Null characters (integer value zero) + are <em>not</em> allowed in filenames (not even at the end). </p> </desc> </datatype> @@ -954,8 +981,7 @@ f.txt: {person, "kalle", 25}. </item> <tag><c>eisdir</c></tag> <item> - <p>The named file is not a regular file. It can be a - directory, a FIFO, or a device.</p> + <p>The named file is a directory.</p> </item> <tag><c>enotdir</c></tag> <item> @@ -1407,8 +1433,12 @@ f.txt: {person, "kalle", 25}. which is 1970-01-01 00:00 UTC.</p></item> </taglist> <p>Default is <c>{time, local}</c>.</p> - <p>If the option <c>raw</c> is set, the file server is not called - and only information about local files is returned.</p> + <p>If the option <c>raw</c> is set, the file server is not called and + only information about local files is returned. Note that this will + break this module's atomicity guarantees as it can race with a + concurrent call to + <seealso marker="#write_file_info/2"><c>write_file_info/1,2</c> + </seealso></p> <note> <p>As file times are stored in POSIX time on most OS, it is faster to query file information with option <c>posix</c>.</p> @@ -1656,8 +1686,12 @@ f.txt: {person, "kalle", 25}. except that if <c><anno>Name</anno></c> is a symbolic link, information about the link is returned in the <c>file_info</c> record and the <c>type</c> field of the record is set to <c>symlink</c>.</p> - <p>If the option <c>raw</c> is set, the file server is not called - and only information about local files is returned.</p> + <p>If the option <c>raw</c> is set, the file server is not called and + only information about local files is returned. Note that this will + break this module's atomicity guarantees as it can race with a + concurrent call to + <seealso marker="#write_file_info/2"><c>write_file_info/1,2</c> + </seealso></p> <p>If <c><anno>Name</anno></c> is not a symbolic link, this function returns the same result as <c>read_file_info/1</c>. On platforms that do not support symbolic links, this function @@ -1795,24 +1829,16 @@ f.txt: {person, "kalle", 25}. <p>The file used must be opened using the <c>raw</c> flag, and the process calling <c>sendfile</c> must be the controlling process of the socket. See <seealso marker="gen_tcp#controlling_process-2"><c>gen_tcp:controlling_process/2</c></seealso>.</p> - <p>If the OS used does not support <c>sendfile</c>, an Erlang fallback - using - <seealso marker="#read/2"><c>read/2</c></seealso> and - <seealso marker="gen_tcp#send/2"><c>gen_tcp:send/2</c></seealso> is used.</p> + <p>If the OS used does not support non-blocking <c>sendfile</c>, an + Erlang fallback using <seealso marker="#read/2"><c>read/2</c></seealso> + and <seealso marker="gen_tcp#send/2"><c>gen_tcp:send/2</c></seealso> is + used.</p> <p>The option list can contain the following options:</p> <taglist> <tag><c>chunk_size</c></tag> <item><p>The chunk size used by the Erlang fallback to send data. If using the fallback, set this to a value that comfortably fits in the systems memory. Default is 20 MB.</p></item> - <tag><c>use_threads</c></tag> - <item><p>Instructs the emulator to use the <c>async</c> thread pool for the - <c>sendfile</c> system call. This can be useful if the OS you are running - on does not properly support non-blocking <c>sendfile</c> calls. Notice that - using <c>async</c> threads potentially makes your system vulnerable to slow - client attacks. If set to <c>true</c> and no <c>async</c> threads are available, - the <c>sendfile</c> call returns <c>{error,einval}</c>. - Introduced in Erlang/OTP 17.0. Default is <c>false</c>.</p></item> </taglist> </desc> </func> @@ -1825,7 +1851,7 @@ f.txt: {person, "kalle", 25}. <p>The functions in the module <c>file</c> usually treat binaries as raw filenames, that is, they are passed "as is" even when the encoding of the binary does not agree with - <seealso marker="#native_name_encoding"><c>native_name_encoding()</c></seealso>. + <seealso marker="#native_name_encoding/0"><c>native_name_encoding()</c></seealso>. However, this function expects binaries to be encoded according to the value returned by <c>native_name_encoding()</c>.</p> <p>Typical error reasons are:</p> @@ -2117,144 +2143,77 @@ f.txt: {person, "kalle", 25}. <section> <title>Performance</title> - <p>Some operating system file operations, for example, a - <c>sync/1</c> or <c>close/1</c> on a huge file, can block their - calling thread for seconds. If this affects the emulator main - thread, the response time is no longer in the order of - milliseconds, depending on the definition of "soft" in soft - real-time system.</p> - <p>If the device driver thread pool is active, file operations are - done through those threads instead, so the emulator can go on - executing Erlang processes. Unfortunately, the time for serving a - file operation increases because of the extra scheduling required - from the operating system.</p> - <p>If the device driver thread pool is disabled or of size 0, large - file reads and writes are segmented into many smaller, which - enable the emulator to serve other processes during the file - operation. This has the same effect as when using the thread - pool, but with larger overhead. Other file operations, for - example, <c>sync/1</c> or <c>close/1</c> on a huge file, still are - a problem.</p> - <p>For increased performance, raw files are recommended. Raw files - use the file system of the host machine of the node.</p> + <p>For increased performance, raw files are recommended.</p> + <p>A normal file is really a process so it can be used as an I/O + device (see <seealso marker="stdlib:io"><c>io</c></seealso>). + Therefore, when data is written to a normal file, the sending of the + data to the file process, copies all data that are not binaries. Opening + the file in binary mode and writing binaries is therefore recommended. + If the file is opened on another node, or if the file server runs as + slave to the file server of another node, also binaries are copied.</p> <note> - <p> - For normal files (non-raw), the file server is used to find the files, - and if the node is running its file server as slave to the file server - of another node, and the other node runs on some other host machine, - they can have different file systems. - However, this is seldom a problem.</p> + <p>Raw files use the file system of the host machine of the node. + For normal files (non-raw), the file server is used to find the files, + and if the node is running its file server as slave to the file server + of another node, and the other node runs on some other host machine, + they can have different file systems. + However, this is seldom a problem.</p> </note> - <p>A normal file is really a process so it can be used as an I/O - device (see - <seealso marker="stdlib:io"><c>io</c></seealso>). - Therefore, when data is written to a - normal file, the sending of the data to the file process, copies - all data that are not binaries. Opening the file in binary mode - and writing binaries is therefore recommended. If the file is - opened on another node, or if the file server runs as slave to - the file server of another node, also binaries are copied.</p> - <p>Caching data to reduce the number of file operations, or rather - the number of calls to the file driver, generally increases - performance. The following function writes 4 MBytes in 23 - seconds when tested:</p> + <p><seealso marker="#open/2"><c>open/2</c></seealso> can be given the + options <c>delayed_write</c> and <c>read_ahead</c> to turn on caching, + which will reduce the number of operating system calls and greatly + improve performance for small reads and writes. However, the overhead + won't disappear completely and it's best to keep the number of file + operations to a minimum. As a contrived example, the following function + writes 4MB in 2.5 seconds when tested:</p> + <code type="none"><![CDATA[ -create_file_slow(Name, N) when integer(N), N >= 0 -> - {ok, FD} = file:open(Name, [raw, write, delayed_write, binary]), - ok = create_file_slow(FD, 0, N), - ok = ?FILE_MODULE:close(FD), - ok. - -create_file_slow(FD, M, M) -> +create_file_slow(Name) -> + {ok, Fd} = file:open(Name, [raw, write, delayed_write, binary]), + create_file_slow_1(Fd, 4 bsl 20), + file:close(Fd). + +create_file_slow_1(_Fd, 0) -> ok; -create_file_slow(FD, M, N) -> - ok = file:write(FD, <<M:32/unsigned>>), - create_file_slow(FD, M+1, N).]]></code> +create_file_slow_1(Fd, M) -> + ok = file:write(Fd, <<0>>), + create_file_slow_1(Fd, M - 1).]]></code> + + <p>The following functionally equivalent code writes 128 bytes per call + to <seealso marker="#write/2"><c>write/2</c></seealso> and so does the + same work in 0.08 seconds, which is roughly 30 times faster:</p> - <p>The following, functionally equivalent, function collects 1024 - entries into a list of 128 32-byte binaries before each call to - <seealso marker="#write/2"><c>write/2</c></seealso> and so - does the same work in 0.52 seconds, - which is 44 times faster:</p> <code type="none"><![CDATA[ -create_file(Name, N) when integer(N), N >= 0 -> - {ok, FD} = file:open(Name, [raw, write, delayed_write, binary]), - ok = create_file(FD, 0, N), - ok = ?FILE_MODULE:close(FD), +create_file(Name) -> + {ok, Fd} = file:open(Name, [raw, write, delayed_write, binary]), + create_file_1(Fd, 4 bsl 20), + file:close(Fd), ok. - -create_file(FD, M, M) -> + +create_file_1(_Fd, 0) -> ok; -create_file(FD, M, N) when M + 1024 =< N -> - create_file(FD, M, M + 1024, []), - create_file(FD, M + 1024, N); -create_file(FD, M, N) -> - create_file(FD, M, N, []). - -create_file(FD, M, M, R) -> - ok = file:write(FD, R); -create_file(FD, M, N0, R) when M + 8 =< N0 -> - N1 = N0-1, N2 = N0-2, N3 = N0-3, N4 = N0-4, - N5 = N0-5, N6 = N0-6, N7 = N0-7, N8 = N0-8, - create_file(FD, M, N8, - [<<N8:32/unsigned, N7:32/unsigned, - N6:32/unsigned, N5:32/unsigned, - N4:32/unsigned, N3:32/unsigned, - N2:32/unsigned, N1:32/unsigned>> | R]); -create_file(FD, M, N0, R) -> - N1 = N0-1, - create_file(FD, M, N1, [<<N1:32/unsigned>> | R]).]]></code> +create_file_1(Fd, M) when M >= 128 -> + ok = file:write(Fd, <<0:(128)/unit:8>>), + create_file_1(Fd, M - 128); +create_file_1(Fd, M) -> + ok = file:write(Fd, <<0:(M)/unit:8>>), + create_file_1(Fd, M - 1).]]></code> - <note> - <p>Trust only your own benchmarks. If the list length in - <c>create_file/2</c> above is increased, it runs slightly - faster, but consumes more memory and causes more memory - fragmentation. How much this affects your application is - something that this simple benchmark cannot predict.</p> - <p>If the size of each binary is increased to 64 bytes, it - also runs slightly faster, but the code is then twice as clumsy. - In the current implementation, binaries larger than 64 bytes are - stored in memory common to all processes and not copied when - sent between processes, while these smaller binaries are stored - on the process heap and copied when sent like any other term.</p> - <p>So, with a binary size of 68 bytes, <c>create_file/2</c> runs - 30 percent slower than with 64 bytes, and causes much more - memory fragmentation. Notice that if the binaries were to be sent - between processes (for example, a non-raw file), the results - would probably be completely different.</p> - </note> - <p>A raw file is really a port. When writing data to a port, it is - efficient to write a list of binaries. It is not needed to - flatten a deep list before writing. On Unix hosts, scatter output, - which writes a set of buffers in one operation, is used when - possible. In this way <c>write(FD, [Bin1, Bin2 | Bin3])</c> - writes the contents of the binaries without copying the data - at all, except for perhaps deep down in the operating system - kernel.</p> - <p>For raw files, <c>pwrite/2</c> and <c>pread/2</c> are - efficiently implemented. The file driver is called only once for - the whole operation, and the list iteration is done in the file - driver.</p> - <p>The options <c>delayed_write</c> and <c>read_ahead</c> to - <seealso marker="#open/2"><c>open/2</c></seealso> - make the file driver cache data to reduce - the number of operating system calls. The function - <c>create_file/2</c> in the recent example takes 60 seconds - without option <c>delayed_write</c>, which is 2.6 - times slower.</p> - <p>As a bad example, <c>create_file_slow/2</c> - without options <c>raw</c>, <c>binary</c>, and <c>delayed_write</c>, - meaning it calls <c>open(Name, [write])</c>, needs - 1 min 20 seconds for the job, which is 3.5 times slower than - the first example, and 150 times slower than the optimized - <c>create_file/2</c>.</p> - <warning> - <p>If an error occurs when accessing an open file with module - <seealso marker="stdlib:io"><c>io</c></seealso>, - the process handling the file exits. The dead - file process can hang if a process tries to access it later. - This will be fixed in a future release.</p> - </warning> + <p>When writing data it's generally more efficient to write a list of + binaries rather than a list of integers. It is not needed to + flatten a deep list before writing. On Unix hosts, scatter output, + which writes a set of buffers in one operation, is used when + possible. In this way <c>write(FD, [Bin1, Bin2 | Bin3])</c> + writes the contents of the binaries without copying the data + at all, except for perhaps deep down in the operating system + kernel.</p> + <warning> + <p>If an error occurs when accessing an open file with module + <seealso marker="stdlib:io"><c>io</c></seealso>, the process + handling the file exits. The dead file process can hang if a process + tries to access it later. This will be fixed in a future release. + </p> + </warning> </section> <section> diff --git a/lib/kernel/doc/src/heart.xml b/lib/kernel/doc/src/heart.xml index 5b5b71e521..ad1a2ffeb9 100644 --- a/lib/kernel/doc/src/heart.xml +++ b/lib/kernel/doc/src/heart.xml @@ -4,7 +4,7 @@ <erlref> <header> <copyright> - <year>1996</year><year>2016</year> + <year>1996</year><year>2018</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> @@ -59,8 +59,9 @@ <pre> % <input>erl -heart -env HEART_BEAT_TIMEOUT 30 ...</input></pre> <p>The value (in seconds) must be in the range 10 < X <= 65535.</p> - <p>Notice that if the system clock is adjusted with - more than <c>HEART_BEAT_TIMEOUT</c> seconds, <c>heart</c> + <p>When running on OSs lacking support for monotonic time, + <c>heart</c> is susceptible to system clock adjustments of more than + <c>HEART_BEAT_TIMEOUT</c> seconds. When this happens, <c>heart</c> times out and tries to reboot the system. This can occur, for example, if the system clock is adjusted automatically by use of the Network Time Protocol (NTP).</p> diff --git a/lib/kernel/doc/src/inet.xml b/lib/kernel/doc/src/inet.xml index 169a76463b..e6a7962c5a 100644 --- a/lib/kernel/doc/src/inet.xml +++ b/lib/kernel/doc/src/inet.xml @@ -4,7 +4,7 @@ <erlref> <header> <copyright> - <year>1997</year><year>2017</year> + <year>1997</year><year>2018</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> @@ -197,6 +197,9 @@ fe80::204:acff:fe17:bf38 <datatype> <name name="address_family"/> </datatype> + <datatype> + <name name="socket_protocol"/> + </datatype> </datatypes> <funcs> @@ -274,9 +277,7 @@ fe80::204:acff:fe17:bf38 <p>Returns a <c>hostent</c> record for the host with the specified hostname.</p> <p>If resolver option <c>inet6</c> is <c>true</c>, - an IPv6 address is looked up. If that fails, - the IPv4 address is looked up and returned on - IPv6-mapped IPv4 format.</p> + an IPv6 address is looked up.</p> </desc> </func> @@ -461,6 +462,61 @@ get_tcpi_sacked(Sock) -> </func> <func> + <name name="i" arity="0" /> + <name name="i" arity="1" /> + <name name="i" arity="2" /> + <fsummary>Displays information and statistics about sockets on the terminal</fsummary> + <desc> + <p> + Lists all TCP, UDP and SCTP sockets, including those that the Erlang runtime system uses as well as + those created by the application. + </p> + <p> + The following options are available: + </p> + + <taglist> + <tag><c>port</c></tag> + <item> + <p>The internal index of the port.</p> + </item> + <tag><c>module</c></tag> + <item> + <p>The callback module of the socket.</p> + </item> + <tag><c>recv</c></tag> + <item> + <p>Number of bytes received by the socket.</p> + </item> + <tag><c>sent</c></tag> + <item> + <p>Number of bytes sent from the socket.</p> + </item> + <tag><c>owner</c></tag> + <item> + <p>The socket owner process.</p> + </item> + <tag><c>local_address</c></tag> + <item> + <p>The local address of the socket.</p> + </item> + <tag><c>foreign_address</c></tag> + <item> + <p>The address and port of the other end of the connection.</p> + </item> + <tag><c>state</c></tag> + <item> + <p>The connection state.</p> + </item> + <tag><c>type</c></tag> + <item> + <p>STREAM or DGRAM or SEQPACKET.</p> + </item> + </taglist> + </desc> + </func> + + <func> <name name="ntoa" arity="1" /> <fsummary>Convert IPv6/IPV4 address to ASCII.</fsummary> <desc> @@ -524,6 +580,19 @@ get_tcpi_sacked(Sock) -> </func> <func> + <name name="ipv4_mapped_ipv6_address" arity="1" /> + <fsummary>Convert to and from IPv4-mapped IPv6 address.</fsummary> + <desc> + <p> + Convert an IPv4 address to an IPv4-mapped IPv6 address + or the reverse. When converting from an IPv6 address + all but the 2 low words are ignored so this function also + works on some other types of addresses than IPv4-mapped. + </p> + </desc> + </func> + + <func> <name name="parse_strict_address" arity="1" /> <fsummary>Parse an IPv4 or IPv6 address strict.</fsummary> <desc> @@ -1080,7 +1149,7 @@ setcap cap_sys_admin,cap_sys_ptrace,cap_dac_read_search+epi beam.smp</code> <seealso marker="gen_tcp#recv/2"><c>gen_tcp:recv/2</c></seealso> gets <c>{error, closed}</c>. In active mode, the controlling process receives a - <c>{tcp_close, Socket}</c> message, indicating that the + <c>{tcp_closed, Socket}</c> message, indicating that the peer has closed the connection.</p> <p>Setting this option to <c>true</c> allows you to distinguish between a connection that was closed normally, @@ -1214,7 +1283,7 @@ inet:setopts(Sock,[{raw,6,8,<<30:32/native>>}]),]]></code> For one-to-many style sockets, the special value <c>0</c> is defined to mean that the returned addresses must be without any particular association. - How different SCTP implementations interprets this varies somewhat. + How different SCTP implementations interpret this varies somewhat. </p> </desc> </func> diff --git a/lib/kernel/doc/src/inet_res.xml b/lib/kernel/doc/src/inet_res.xml index 4ada4203c0..351d86a93a 100644 --- a/lib/kernel/doc/src/inet_res.xml +++ b/lib/kernel/doc/src/inet_res.xml @@ -4,7 +4,7 @@ <erlref> <header> <copyright> - <year>2009</year><year>2015</year> + <year>2009</year><year>2018</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> @@ -130,7 +130,7 @@ dns_header() = DnsHeader inet_dns:header(DnsHeader) -> [ {id, integer()} | {qr, boolean()} - | {opcode, 'query' | iquery | status | integer()} + | {opcode, query | iquery | status | integer()} | {aa, boolean()} | {tc, boolean()} | {rd, boolean()} @@ -230,9 +230,7 @@ inet_dns:record_type(_) -> undefined.</pre> <seealso marker="#getbyname/2"><c>getbyname/2,3</c></seealso>. </p> <p>If resolver option <c>inet6</c> is <c>true</c>, - an IPv6 address is looked up. If that fails, - the IPv4 address is looked up and returned on - IPv6-mapped IPv4 format.</p> + an IPv6 address is looked up.</p> </desc> </func> diff --git a/lib/kernel/doc/src/introduction_chapter.xml b/lib/kernel/doc/src/introduction_chapter.xml new file mode 100644 index 0000000000..d02b1a2ee5 --- /dev/null +++ b/lib/kernel/doc/src/introduction_chapter.xml @@ -0,0 +1,63 @@ +<?xml version="1.0" encoding="utf-8" ?> +<!DOCTYPE chapter SYSTEM "chapter.dtd"> + +<chapter> + <header> + <copyright> + <year>2017</year><year>2018</year> + <holder>Ericsson AB. All Rights Reserved.</holder> + </copyright> + <legalnotice> + Licensed under the Apache License, Version 2.0 (the "License"); + you may not use this file except in compliance with the License. + You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + + Unless required by applicable law or agreed to in writing, software + distributed under the License is distributed on an "AS IS" BASIS, + WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + See the License for the specific language governing permissions and + limitations under the License. + + </legalnotice> + + <title>Introduction</title> + <prepared></prepared> + <responsible></responsible> + <docno></docno> + <approved></approved> + <checked></checked> + <date></date> + <rev></rev> + <file>introduction.xml</file> + </header> + + <section> + <title>Scope</title> + <p>The Kernel application has all the code necessary to run + the Erlang runtime system: file servers, code servers, + and so on.</p> + <p>The Kernel application is the first application started. It is + mandatory in the sense that the minimal system based on + Erlang/OTP consists of Kernel and STDLIB. Kernel + contains the following functional areas:</p> + <list type="bulleted"> + <item>Start, stop, supervision, configuration, and distribution of applications</item> + <item>Code loading</item> + <item>Logging</item> + <item>Global name service</item> + <item>Supervision of Erlang/OTP</item> + <item>Communication with sockets</item> + <item>Operating system interface</item> + </list> + </section> + + <section> + <title>Prerequisites</title> + <p>It is assumed that the reader is familiar with the Erlang programming + language.</p> + </section> +</chapter> + + diff --git a/lib/kernel/doc/src/kernel_app.xml b/lib/kernel/doc/src/kernel_app.xml index 0762cebc94..ccb7d17d25 100644 --- a/lib/kernel/doc/src/kernel_app.xml +++ b/lib/kernel/doc/src/kernel_app.xml @@ -42,7 +42,6 @@ <item>Start, stop, supervision, configuration, and distribution of applications</item> <item>Code loading</item> <item>Logging</item> - <item>Error logging</item> <item>Global name service</item> <item>Supervision of Erlang/OTP</item> <item>Communication with sockets</item> @@ -51,10 +50,13 @@ </description> <section> - <title>Error Logger Event Handlers</title> - <p>Two standard error logger event handlers are defined in - the Kernel application. These are described in - <seealso marker="error_logger"><c>error_logger(3)</c></seealso>.</p> + <title>Logger Handlers</title> + <p>Two standard logger handlers are defined in + the Kernel application. These are described in the + <seealso marker="logger_chapter">Kernel User's Guide</seealso>, + and in the <seealso marker="logger_std_h"><c>logger_std_h(3)</c></seealso> + and <seealso marker="logger_disk_log_h"><c>logger_disk_log_h(3)</c> + </seealso> manual pages.</p> </section> <section> @@ -113,26 +115,12 @@ </section> <section> + <marker id="configuration"/> <title>Configuration</title> <p>The following configuration parameters are defined for the Kernel application. For more information about configuration parameters, see file <seealso marker="app"><c>app(4)</c></seealso>.</p> <taglist> - <tag><c>browser_cmd = string() | {M,F,A}</c></tag> - <item> - <p>When pressing the <em>Help</em> button in a tool such as Debugger, - the help text (an HTML file <c>File</c>) is by default - displayed in a Netscape browser, which is required to be - operational. This parameter can be used to change the command for - how to display the help text if another browser than Netscape - is preferred, or if another platform than Unix or Windows is - used.</p> - <p>If set to a string <c>Command</c>, the command - <c>"Command File"</c> is evaluated using - <seealso marker="os#cmd/1"><c>os:cmd/1</c></seealso>.</p> - <p>If set to a module-function-args tuple, <c>{M,F,A}</c>, - the call <c>apply(M,F,[File|A])</c> is evaluated.</p> - </item> <tag><c>distributed = [Distrib]</c></tag> <item> <p>Specifies which applications that are distributed and on which @@ -176,65 +164,74 @@ <p>Permissions are described in <seealso marker="application#permit/2"><c>application:permit/2</c></seealso>.</p> </item> - <tag><c>error_logger = Value</c></tag> - <item> - <p><c>Value</c> is one of:</p> - <taglist> - <tag><c>tty</c></tag> - <item><p>Installs the standard event handler, which prints error - reports to <c>stdio</c>. This is the default option.</p></item> - <tag><c>{file, FileName}</c></tag> - <item><p>Installs the standard event handler, which prints error - reports to file <c>FileName</c>, where <c>FileName</c> - is a string. The file is opened with encoding UTF-8.</p></item> - <tag><c>false</c></tag> - <item> - <p>No standard event handler is installed, but - the initial, primitive event handler is kept, printing - raw event messages to <c>tty</c>.</p> - </item> - <tag><c>silent</c></tag> - <item> - <p>Error logging is turned off.</p> - </item> - </taglist> + <tag><marker id="logger"/><c>logger = [Config]</c></tag> + <item> + <p>Specifies the configuration + for <seealso marker="logger">Logger</seealso>, except the + primary log level, which is specified + with <seealso marker="#logger_level"><c>logger_level</c></seealso>, + and the compatibility + with <seealso marker="sasl:error_logging">SASL Error + Logging</seealso>, which is specified + with <seealso marker="#logger_sasl_compatible"> + <c>logger_sasl_compatible</c></seealso>.</p> + <p>The <c>logger </c> parameter is described in + section <seealso marker="logger_chapter#logger_parameter"> + Logging</seealso> in the Kernel User's Guide.</p> + </item> + <tag><marker id="logger_level"/><c>logger_level = Level</c></tag> + <item> + <p>Specifies the primary log level for Logger. Log events with + the same, or a more severe level, pass through the primary + log level check. See + section <seealso marker="logger_chapter">Logging</seealso> + in the Kernel User's Guide for more information about Logger + and log levels.</p> + <p><c>Level = emergency | alert | critical | error | warning | + notice | info | debug | all | none</c></p> + <p>To change the primary log level at runtime, use + <seealso marker="logger#set_primary_config/2"> + <c>logger:set_primary_config(level, Level)</c></seealso>.</p> + <p>Defaults to <c>info</c>.</p> + </item> + <tag><marker id="logger_sasl_compatible"/> + <c>logger_sasl_compatible = true | false</c></tag> + <item> + <p>Specifies if Logger behaves backwards compatible with the + SASL error logging functionality from releases prior to + Erlang/OTP 21.0.</p> + <p>If this parameter is set to <c>true</c>, the default Logger + handler does not log any progress-, crash-, or supervisor + reports. If the SASL application is then started, it adds a + Logger handler named <c>sasl</c>, which logs these events + according to values of the SASL configuration + parameter <c>sasl_error_logger</c> + and <c>sasl_errlog_type</c>.</p> + <p>See section + <seealso marker="sasl:sasl_app#deprecated_error_logger_config"> + Deprecated Error Logger Event Handlers and + Configuration</seealso> in the sasl(6) manual page for + information about the SASL configuration parameters.</p> + <p>See section <seealso marker="sasl:error_logging">SASL Error + Logging</seealso> in the SASL User's Guide, and + section <seealso marker="logger_chapter#compatibility">Backwards + Compatibility with error_logger</seealso> in the Kernel + User's Guide for information about the SASL error logging + functionality, and how Logger can be backwards compatible + with this.</p> + <p>Defaults to <c>false</c>.</p> + <note> + <p>If this parameter is set to <c>true</c>, + <c>sasl_errlog_type</c> indicates that progress reports + shall be logged, and the configured primary log level + is <c>notice</c> or more severe, then SASL automatically + sets the primary log level to <c>info</c>. That is, this + setting can potentially overwrite the value of the Kernel + configuration parameter <c>logger_level</c>. This is to + allow progress reports, which have log level <c>info</c>, + to be forwarded to the handlers.</p> + </note> </item> - <tag><c>error_logger_format_depth = Depth</c></tag> - <item> - <marker id="error_logger_format_depth"></marker> - <p>Can be used to limit the size of the - formatted output from the error logger event handlers.</p> - - <note><p>This configuration parameter was introduced in OTP 18.1 - and is experimental. Based on user feedback, it - can be changed or improved in future releases, for example, - to gain better control over how to limit the size of the - formatted output. We have no plans to remove this - new feature entirely, unless it turns out to be - useless.</p></note> - - <p><c>Depth</c> is a positive integer representing the maximum - depth to which terms are printed by the error logger event - handlers included in OTP. This - configuration parameter is used by the two event handlers - defined by the Kernel application and the two event - handlers in the SASL application. - (If you have implemented your own error handlers, this configuration - parameter has no effect on them.)</p> - - <p><c>Depth</c> is used as follows: Format strings - passed to the event handlers are rewritten. - The format controls <c>~p</c> and <c>~w</c> are replaced with - <c>~P</c> and <c>~W</c>, respectively, and <c>Depth</c> is - used as the depth parameter. For details, see - <seealso marker="stdlib:io#format/2"><c>io:format/2</c></seealso> - in STDLIB.</p> - - <note><p>A reasonable starting value for <c>Depth</c> is - <c>30</c>. We recommend to test crashing various processes in your - application, examine the logs from the crashes, and then - increase or decrease the value.</p></note> - </item> <tag><c>global_groups = [GroupTuple]</c></tag> <item> <marker id="global_groups"></marker> @@ -286,9 +283,8 @@ </item> <tag><c>inet_parse_error_log = silent</c></tag> <item> - <p>If set, no - <c>error_logger</c> messages are generated when erroneous - lines are found and skipped in the various Inet configuration + <p>If set, no log events are issued when erroneous lines are + found and skipped in the various Inet configuration files.</p> </item> <tag><c>inetrc = Filename</c></tag> @@ -314,24 +310,31 @@ <tag><c>net_ticktime = TickTime</c></tag> <item> <marker id="net_ticktime"></marker> - <p>Specifies the <c>net_kernel</c> tick time. <c>TickTime</c> - is specified in seconds. Once every <c>TickTime/4</c> second, all - connected nodes are ticked (if anything else is written - to a node). If nothing is received from another node - within the last four tick times, that node is considered - to be down. This ensures that nodes that are not responding, - for reasons such as hardware errors, are considered to be - down.</p> - <p>The time <c>T</c>, in which a node that is not responding is - detected, is calculated as <c><![CDATA[MinT < T < MaxT]]></c>, where:</p> + <p>Specifies the <c>net_kernel</c> tick time in seconds. This is the + approximate time a connected node may be unresponsive until it is + considered down and thereby disconnected.</p> + <p>Once every <c>TickTime/4</c> seconds, each connected node is ticked + if nothing has been sent to it during that last <c>TickTime/4</c> + interval. A tick is a small package sent on the connection. A connected + node is considered to be down if no ticks or payload packages have been + received during the last four <c>TickTime/4</c> intervals. This ensures + that nodes that are not responding, for reasons such as hardware errors, + are considered to be down.</p> + <p>As the availability is only checked every <c>TickTime/4</c> seconds, + the actual time <c>T</c> a node have been unresponsive when + detected may vary between <c>MinT</c> and <c>MaxT</c>, + where:</p> <code type="none"> MinT = TickTime - TickTime / 4 MaxT = TickTime + TickTime / 4</code> - <p><c>TickTime</c> defaults to <c>60</c> (seconds). Thus, - <c><![CDATA[45 < T < 75]]></c> seconds.</p> - <p>Notice that <em>all</em> communicating nodes are to have the <em>same</em> - <c>TickTime</c> value specified.</p> - <p>Normally, a terminating node is detected immediately.</p> + <p><c>TickTime</c> defaults to <c>60</c> seconds. Thus, + <c><![CDATA[45 < T < 75]]></c> seconds.</p> + <p>Notice that <em>all</em> communicating nodes are to have the + <em>same</em> <c>TickTime</c> value specified, as it determines both the + frequency of outgoing ticks and the expected frequency of incominging + ticks.</p> + <p>Normally, a terminating node is detected immediately by the transport + protocol (like TCP/IP).</p> </item> <tag><c>shutdown_timeout = integer() | infinity</c></tag> <item> @@ -497,6 +500,37 @@ MaxT = TickTime + TickTime / 4</code> </section> <section> + <title>Deprecated Configuration Parameters</title> + <p>In Erlang/OTP 21.0, a new API for logging was added. The + old <c>error_logger</c> event manager, and event handlers + running on this manager, still work, but they are no longer used + by default.</p> + <p>The following application configuration parameters can still be + set, but they are only used if the corresponding configuration + parameters for Logger are not set.</p> + <taglist> + <tag><c>error_logger</c></tag> + <item>Replaced by setting the type of the default + <seealso marker="logger_std_h#type"><c>logger_std_h</c></seealso> + to the same value. Example: + <code type="none"> +erl -kernel logger '[{handler,default,logger_std_h,#{config=>#{type=>{file,"/tmp/erlang.log"}}}}]' + </code> + </item> + <tag><c>error_logger_format_depth</c></tag> + <item>Replaced by setting the <seealso marker="logger_formatter#depth"><c>depth</c></seealso> + parameter of the default handlers formatter. Example: + <code type="none"> +erl -kernel logger '[{handler,default,logger_std_h,#{formatter=>{logger_formatter,#{legacy_header=>true,template=>[{logger_formatter,header},"\n",msg,"\n"],depth=>10}}}]' + </code> + </item> + </taglist> + <p>See <seealso marker="logger_chapter#compatibility">Backwards + compatibility with error_logger</seealso> for more + information.</p> + </section> + + <section> <title>See Also</title> <p><seealso marker="app"><c>app(4)</c></seealso>, <seealso marker="application"><c>application(3)</c></seealso>, @@ -504,12 +538,12 @@ MaxT = TickTime + TickTime / 4</code> <seealso marker="disk_log"><c>disk_log(3)</c></seealso>, <seealso marker="erl_boot_server"><c>erl_boot_server(3)</c></seealso>, <seealso marker="erl_ddll"><c>erl_ddll(3)</c></seealso>, - <seealso marker="error_logger"><c>error_logger(3)</c></seealso>, <seealso marker="file"><c>file(3)</c></seealso>, <seealso marker="global"><c>global(3)</c></seealso>, <seealso marker="global_group"><c>global_group(3)</c></seealso>, <seealso marker="heart"><c>heart(3)</c></seealso>, <seealso marker="inet"><c>inet(3)</c></seealso>, + <seealso marker="logger"><c>logger(3)</c></seealso>, <seealso marker="net_kernel"><c>net_kernel(3)</c></seealso>, <seealso marker="os"><c>os(3)</c></seealso>, <seealso marker="pg2"><c>pg2(3)</c></seealso>, diff --git a/lib/kernel/doc/src/logger.xml b/lib/kernel/doc/src/logger.xml new file mode 100644 index 0000000000..f1830a8224 --- /dev/null +++ b/lib/kernel/doc/src/logger.xml @@ -0,0 +1,1169 @@ +<?xml version="1.0" encoding="utf-8" ?> +<!DOCTYPE erlref SYSTEM "erlref.dtd"> + +<erlref> + <header> + <copyright> + <year>2017</year><year>2018</year> + <holder>Ericsson AB. All Rights Reserved.</holder> + </copyright> + <legalnotice> + Licensed under the Apache License, Version 2.0 (the "License"); + you may not use this file except in compliance with the License. + You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + + Unless required by applicable law or agreed to in writing, software + distributed under the License is distributed on an "AS IS" BASIS, + WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + See the License for the specific language governing permissions and + limitations under the License. + + </legalnotice> + + <title>logger</title> + <prepared></prepared> + <responsible></responsible> + <docno></docno> + <approved></approved> + <checked></checked> + <date></date> + <rev>A</rev> + <file>logger.xml</file> + </header> + <module>logger</module> + <modulesummary>API module for Logger, the standard logging facility + in Erlang/OTP.</modulesummary> + + <description> + <p>This module implements the main API for logging in + Erlang/OTP. To create a log event, use the + <seealso marker="#logging_API">API functions</seealso> or the + log + <seealso marker="#macros">macros</seealso>, for example:</p> + <code> +?LOG_ERROR("error happened because: ~p", [Reason]). % With macro +logger:error("error happened because: ~p", [Reason]). % Without macro + </code> + <p>To configure the Logger backend, + use <seealso marker="kernel_app#logger">Kernel configuration + parameters</seealso> + or <seealso marker="#configuration_API">configuration + functions</seealso> in the Logger API.</p> + + <p>By default, the Kernel application installs one log handler at + system start. This handler is named <c>default</c>. It receives + and processes standard log events produced by the Erlang runtime + system, standard behaviours and different Erlang/OTP + applications. The log events are by default printed to the + terminal.</p> + <p>If you want your systems logs to be printed to a file instead, + you must configure the default handler to do so. The simplest + way is to include the following in + your <seealso marker="config"><c>sys.config</c></seealso>:</p> + <code> +[{kernel, + [{logger, + [{handler, default, logger_std_h, + #{config => #{type => {file, "path/to/file.log"}}}}]}]}]. + </code> + <p> + For more information about: + </p> + <list type="bulleted"> + <item>the Logger facility in general, see + the <seealso marker="logger_chapter">User's + Guide</seealso>.</item> + <item>how to configure Logger, see + the <seealso marker="logger_chapter#configuration">Configuration</seealso> + section in the User's Guide.</item> + <item>the built-in handlers, + see <seealso marker="logger_std_h">logger_std_h</seealso> and + <seealso marker="logger_disk_log_h">logger_disk_log_h</seealso>.</item> + <item>the built-in formatter, + see <seealso marker="logger_formatter">logger_formatter</seealso>.</item> + <item>built-in filters, + see <seealso marker="logger_filters">logger_filters</seealso>.</item> + </list> + + <note> + <p>Since Logger is new in Erlang/OTP 21.0, we do reserve the right + to introduce changes to the Logger API and functionality in + patches following this release. These changes might or might not + be backwards compatible with the initial version.</p> + </note> + + </description> + + <datatypes> + <datatype> + <name name="filter"/> + <desc> + <p>A filter which can be installed as a handler filter, or as + a primary filter in Logger.</p> + </desc> + </datatype> + <datatype> + <name name="filter_arg"/> + <desc> + <p>The second argument to the filter fun.</p> + </desc> + </datatype> + <datatype> + <name name="filter_id"/> + <desc> + <p>A unique identifier for a filter.</p> + </desc> + </datatype> + <datatype> + <name name="filter_return"/> + <desc> + <p>The return value from the filter fun.</p> + </desc> + </datatype> + <datatype> + <name name="formatter_config"/> + <desc> + <p>Configuration data for the + formatter. See <seealso marker="logger_formatter"> + <c>logger_formatter(3)</c></seealso> + for an example of a formatter implementation.</p> + </desc> + </datatype> + <datatype> + <name name="handler_config"/> + <desc> + <p>Handler configuration data for Logger. The following + default values apply:</p> + <list> + <item><c>level => all</c></item> + <item><c>filter_default => log</c></item> + <item><c>filters => []</c></item> + <item><c>formatter => {logger_formatter, DefaultFormatterConfig</c>}</item> + </list> + <p>In addition to these, the following fields are + automatically inserted by Logger, values taken from the + two first parameters + to <seealso marker="#add_handler-3"><c>add_handler/3</c></seealso>:</p> + <list> + <item><c>id => HandlerId</c></item> + <item><c>module => Module</c></item> + </list> + <p>These are read-only and cannot be changed in runtime.</p> + <p>Handler specific configuration data is inserted by the + handler callback itself, in a sub structure associated with + the field named <c>config</c>. See + the <seealso marker="logger_std_h"><c>logger_std_h(3)</c></seealso> + and <seealso marker="logger_disk_log_h"><c>logger_disk_log_h</c></seealso> + manual pages for information about the specifc configuration + for these handlers.</p> + <p>See the <seealso marker="logger_formatter#type-config"> + <c>logger_formatter(3)</c></seealso> manual page for + information about the default configuration for this + formatter.</p> + </desc> + </datatype> + <datatype> + <name name="handler_id"/> + <desc> + <p>A unique identifier for a handler instance.</p> + </desc> + </datatype> + <datatype> + <name name="level"/> + <desc> + <p>The severity level for the message to be logged.</p> + </desc> + </datatype> + <datatype> + <name name="log_event"/> + <desc> + <p></p> + </desc> + </datatype> + <datatype> + <name name="metadata"/> + <desc> + <p>Metadata for the log event.</p> + <p>Logger adds the following metadata to each log event:</p> + <list> + <item><c>pid => self()</c></item> + <item><c>gl => group_leader()</c></item> + <item><c>time => erlang:system_time(microsecond)</c></item> + </list> + <p>When a log macro is used, Logger also inserts location + information:</p> + <list> + <item><c>mfa => {?MODULE, ?FUNCTION_NAME, ?FUNCTION_ARITY}</c></item> + <item><c>file => ?FILE</c></item> + <item><c>line => ?LINE</c></item> + </list> + <p>You can add custom metadata, either by specifying a map as + the last parameter to any of the log macros or the API + functions, or by setting process metadata + with <seealso marker="#set_process_metadata-1"> + <c>set_process_metadata/1</c></seealso> + or <seealso marker="#update_process_metadata-1"> + <c>update_process_metadata/1</c></seealso>.</p> + <p>Logger merges all the metadata maps before forwarding the + log event to the handlers. If the same keys occur, values + from the log call overwrite process metadata, which in turn + overwrite values set by Logger.</p> + <p>The following custom metadata keys have special meaning:</p> + <taglist> + <tag><c>domain</c></tag> + <item> + <p>The value associated with this key is used by filters + for grouping log events originating from, for example, + specific functional + areas. See <seealso marker="logger_filters#domain-2"> + <c>logger_filters:domain/2</c></seealso> + for a description of how this field can be used.</p> + </item> + <tag><c>report_cb</c></tag> + <item> + <p>If the log message is specified as + a <seealso marker="#type-report"><c>report()</c></seealso>, + the <c>report_cb</c> key can be associated with a fun + (report callback) that converts the report to a format + string and arguments, or directly to a string. See the + type definition + of <seealso marker="#type-report_cb"><c>report_cb()</c></seealso>, + and + section <seealso marker="logger_chapter#log_message">Log + Message</seealso> in the User's Guide for more + information about report callbacks.</p> + </item> + </taglist> + </desc> + </datatype> + <datatype> + <name name="msg_fun"/> + <desc> + <p></p> + </desc> + </datatype> + <datatype> + <name name="primary_config"/> + <desc> + <p>Primary configuration data for Logger. The following + default values apply:</p> + <list> + <item><c>level => info</c></item> + <item><c>filter_default => log</c></item> + <item><c>filters => []</c></item> + </list> + </desc> + </datatype> + <datatype> + <name name="report"/> + <desc> + <p></p> + </desc> + </datatype> + <datatype> + <name name="report_cb"/> + <desc> + <p>A fun which converts a <seealso marker="#type-report"><c>report()</c> + </seealso> to a format string and arguments, or directly to a string. + See section <seealso marker="logger_chapter#log_message">Log + Message</seealso> in the User's Guide for more + information.</p> + </desc> + </datatype> + <datatype> + <name name="report_cb_config"/> + <desc> + <p></p> + </desc> + </datatype> + <datatype> + <name name="timestamp"/> + <desc> + <p>A timestamp produced + with <seealso marker="erts:erlang#system_time-1"> + <c>erlang:system_time(microsecond)</c></seealso>.</p> + </desc> + </datatype> + </datatypes> + + <section> + <title>Macros</title> + <p>The following macros are defined:</p> + + <list> + <item><c>?LOG_EMERGENCY(StringOrReport[,Metadata])</c></item> + <item><c>?LOG_EMERGENCY(FunOrFormat,Args[,Metadata])</c></item> + <item><c>?LOG_ALERT(StringOrReport[,Metadata])</c></item> + <item><c>?LOG_ALERT(FunOrFormat,Args[,Metadata])</c></item> + <item><c>?LOG_CRITICAL(StringOrReport[,Metadata])</c></item> + <item><c>?LOG_CRITICAL(FunOrFormat,Args[,Metadata])</c></item> + <item><c>?LOG_ERROR(StringOrReport[,Metadata])</c></item> + <item><c>?LOG_ERROR(FunOrFormat,Args[,Metadata])</c></item> + <item><c>?LOG_WARNING(StringOrReport[,Metadata])</c></item> + <item><c>?LOG_WARNING(FunOrFormat,Args[,Metadata])</c></item> + <item><c>?LOG_NOTICE(StringOrReport[,Metadata])</c></item> + <item><c>?LOG_NOTICE(FunOrFormat,Args[,Metadata])</c></item> + <item><c>?LOG_INFO(StringOrReport[,Metadata])</c></item> + <item><c>?LOG_INFO(FunOrFormat,Args[,Metadata])</c></item> + <item><c>?LOG_DEBUG(StringOrReport[,Metadata])</c></item> + <item><c>?LOG_DEBUG(FunOrFormat,Args[,Metadata])</c></item> + <item><c>?LOG(Level,StringOrReport[,Metadata])</c></item> + <item><c>?LOG(Level,FunOrFormat,Args[,Metadata])</c></item> + </list> + + <p>All macros expand to a call to Logger, where <c>Level</c> is + taken from the macro name, or from the first argument in the + case of the <c>?LOG</c> macro. Location data is added to the + metadata as described under + the <seealso marker="#type-metadata"><c>metadata()</c></seealso> + type definition.</p> + + <p>The call is wrapped in a case statement and will be evaluated + only if <c>Level</c> is equal to or below the configured log + level.</p> + </section> + + <section> + <marker id="logging_API"/> + <title>Logging API functions</title> + </section> + <funcs> + <func> + <name>emergency(StringOrReport[,Metadata])</name> + <name>emergency(Format,Args[,Metadata])</name> + <name>emergency(Fun,FunArgs[,Metadata])</name> + <fsummary>Logs the given message as level <c>emergency</c>.</fsummary> + <desc> + <p>Equivalent to + <seealso marker="#log-2"><c>log(emergency,...)</c></seealso>.</p> + </desc> + </func> + + <func> + <name>alert(StringOrReport[,Metadata])</name> + <name>alert(Format,Args[,Metadata])</name> + <name>alert(Fun,FunArgs[,Metadata])</name> + <fsummary>Logs the given message as level <c>alert</c>.</fsummary> + <desc> + <p>Equivalent to + <seealso marker="#log-2"><c>log(alert,...)</c></seealso>.</p> + </desc> + </func> + + <func> + <name>critical(StringOrReport[,Metadata])</name> + <name>critical(Format,Args[,Metadata])</name> + <name>critical(Fun,FunArgs[,Metadata])</name> + <fsummary>Logs the given message as level <c>critical</c>.</fsummary> + <desc> + <p>Equivalent to + <seealso marker="#log-2"><c>log(critical,...)</c></seealso>.</p> + </desc> + </func> + + <func> + <name>error(StringOrReport[,Metadata])</name> + <name>error(Format,Args[,Metadata])</name> + <name>error(Fun,FunArgs[,Metadata])</name> + <fsummary>Logs the given message as level <c>error</c>.</fsummary> + <desc> + <p>Equivalent to + <seealso marker="#log-2"><c>log(error,...)</c></seealso>.</p> + </desc> + </func> + + <func> + <name>warning(StringOrReport[,Metadata])</name> + <name>warning(Format,Args[,Metadata])</name> + <name>warning(Fun,FunArgs[,Metadata])</name> + <fsummary>Logs the given message as level <c>warning</c>.</fsummary> + <desc> + <p>Equivalent to + <seealso marker="#log-2"><c>log(warning,...)</c></seealso>.</p> + </desc> + </func> + + <func> + <name>notice(StringOrReport[,Metadata])</name> + <name>notice(Format,Args[,Metadata])</name> + <name>notice(Fun,FunArgs[,Metadata])</name> + <fsummary>Logs the given message as level <c>notice</c>.</fsummary> + <desc> + <p>Equivalent to + <seealso marker="#log-2"><c>log(notice,...)</c></seealso>.</p> + </desc> + </func> + + <func> + <name>info(StringOrReport[,Metadata])</name> + <name>info(Format,Args[,Metadata])</name> + <name>info(Fun,FunArgs[,Metadata])</name> + <fsummary>Logs the given message as level <c>info</c>.</fsummary> + <desc> + <p>Equivalent to + <seealso marker="#log-2"><c>log(info,...)</c></seealso>.</p> + </desc> + </func> + + <func> + <name>debug(StringOrReport[,Metadata])</name> + <name>debug(Format,Args[,Metadata])</name> + <name>debug(Fun,FunArgs[,Metadata])</name> + <fsummary>Logs the given message as level <c>debug</c>.</fsummary> + <desc> + <p>Equivalent to + <seealso marker="#log-2"><c>log(debug,...)</c></seealso>.</p> + </desc> + </func> + + <func> + <name name="log" arity="2"/> + <name name="log" arity="3" clause_i="1"/> + <name name="log" arity="3" clause_i="2"/> + <name name="log" arity="3" clause_i="3"/> + <name name="log" arity="4" clause_i="1"/> + <name name="log" arity="4" clause_i="2"/> + <fsummary>Logs the given message.</fsummary> + <type variable="Level"/> + <type variable="StringOrReport" name_i="1"/> + <type variable="Format" name_i="3"/> + <type variable="Args" name_i="3"/> + <type variable="Fun" name_i="4"/> + <type variable="FunArgs" name_i="4"/> + <type variable="Metadata"/> + <desc> + <p>Log the given message.</p> + </desc> + </func> + </funcs> + + <section> + <marker id="configuration_API"/> + <title>Configuration API functions</title> + </section> + <funcs> + <func> + <name name="add_handler" arity="3"/> + <fsummary>Add a handler with the given configuration.</fsummary> + <desc> + <p>Add a handler with the given configuration.</p> + <p><c><anno>HandlerId</anno></c> is a unique identifier which + must be used in all subsequent calls referring to this + handler.</p> + </desc> + </func> + + <func> + <name name="add_handler_filter" arity="3"/> + <fsummary>Add a filter to the specified handler.</fsummary> + <desc> + <p>Add a filter to the specified handler.</p> + <p>The filter fun is called with the log event as the first + parameter, and the specified <c>filter_args()</c> as the + second parameter.</p> + <p>The return value of the fun specifies if a log event is to + be discarded or forwarded to the handler callback:</p> + <taglist> + <tag><c>log_event()</c></tag> + <item> + <p>The filter <em>passed</em>. The next handler filter, if + any, is applied. If no more filters exist for this + handler, the log event is forwarded to the handler + callback.</p> + </item> + <tag><c>stop</c></tag> + <item> + <p>The filter <em>did not pass</em>, and the log event is + immediately discarded.</p> + </item> + <tag><c>ignore</c></tag> + <item> + <p>The filter has no knowledge of the log event. The next + handler filter, if any, is applied. If no more filters + exist for this handler, the value of + the <c>filter_default</c> configuration parameter for + the handler specifies if the log event shall be + discarded or forwarded to the handler callback.</p> + </item> + </taglist> + <p>See + section <seealso marker="logger_chapter#filters">Filters</seealso> + in the User's Guide for more information about filters.</p> + <p>Some built-in filters exist. These are defined in + <seealso marker="logger_filters"><c>logger_filters</c></seealso>.</p> + </desc> + </func> + + <func> + <name name="add_handlers" arity="1" clause_i="1"/> + <fsummary>Set up log handlers from the application's + configuration parameters.</fsummary> + <desc> + <p>Reads the application configuration parameter <c>logger</c> and + calls <c>add_handlers/1</c> with its contents.</p> + </desc> + </func> + + <func> + <name name="add_handlers" arity="1" clause_i="2"/> + <fsummary>Setup logger handlers.</fsummary> + <type name="config_handler"/> + <desc> + <p>This function should be used by custom Logger handlers to make + configuration consistent no matter which handler the system uses. + Normal usage is to add a call to <c>logger:add_handlers/1</c> + just after the processes that the handler needs are started, + and pass the application's <c>logger</c> configuration as the argument. + For example:</p> + <code> +-behaviour(application). +start(_, []) -> + case supervisor:start_link({local, my_sup}, my_sup, []) of + {ok, Pid} -> + ok = logger:add_handlers(my_app), + {ok, Pid, []}; + Error -> Error + end.</code> + <p>This reads the <c>logger</c> configuration parameter from + the <c>my_all</c> application and starts the configured + handlers. The contents of the configuration use the same + rules as the + <seealso marker="logger_chapter#handler-configuration">logger handler configuration</seealso>. + </p> + <p>If the handler is meant to replace the default handler, the Kernel's + default handler have to be disabled before the new handler is added. + A <c>sys.config</c> file that disables the Kernel handler and adds + a custom handler could look like this:</p> + <code> +[{kernel, + [{logger, + %% Disable the default Kernel handler + [{handler, default, undefined}]}]}, + {my_app, + [{logger, + %% Enable this handler as the default + [{handler, default, my_handler, #{}}]}]}]. + </code> + </desc> + </func> + + <func> + <name name="add_primary_filter" arity="2"/> + <fsummary>Add a primary filter to Logger.</fsummary> + <desc> + <p>Add a primary filter to Logger.</p> + <p>The filter fun is called with the log event as the first + parameter, and the specified <c>filter_args()</c> as the + second parameter.</p> + <p>The return value of the fun specifies if a log event is to + be discarded or forwarded to the handlers:</p> + <taglist> + <tag><c>log_event()</c></tag> + <item> + <p>The filter <em>passed</em>. The next primary filter, if + any, is applied. If no more primary filters exist, the + log event is forwarded to the handler part of Logger, + where handler filters are applied.</p> + </item> + <tag><c>stop</c></tag> + <item> + <p>The filter <em>did not pass</em>, and the log event is + immediately discarded.</p> + </item> + <tag><c>ignore</c></tag> + <item> + <p>The filter has no knowledge of the log event. The next + primary filter, if any, is applied. If no more primary + filters exist, the value of the + primary <c>filter_default</c> configuration parameter + specifies if the log event shall be discarded or + forwarded to the handler part.</p> + </item> + </taglist> + <p>See section <seealso marker="logger_chapter#filters"> + Filters</seealso> in the User's Guide for more information + about filters.</p> + <p>Some built-in filters exist. These are defined + in <seealso marker="logger_filters"><c>logger_filters</c></seealso>.</p> + </desc> + </func> + + <func> + <name name="get_config" arity="0"/> + <fsummary>Look up the current Logger configuration</fsummary> + <desc> + <p>Look up all current Logger configuration, including primary + and handler configuration, and module level settings.</p> + </desc> + </func> + + <func> + <name name="get_handler_config" arity="0"/> + <fsummary>Look up the current configuration for all handlers.</fsummary> + <desc> + <p>Look up the current configuration for all handlers.</p> + </desc> + </func> + + <func> + <name name="get_handler_config" arity="1"/> + <fsummary>Look up the current configuration for the given + handler.</fsummary> + <desc> + <p>Look up the current configuration for the given handler.</p> + </desc> + </func> + + <func> + <name name="get_handler_ids" arity="0"/> + <fsummary>Look up the identities for all installed handlers.</fsummary> + <desc> + <p>Look up the identities for all installed handlers.</p> + </desc> + </func> + + <func> + <name name="get_primary_config" arity="0"/> + <fsummary>Look up the current primary configuration for Logger.</fsummary> + <desc> + <p>Look up the current primary configuration for Logger.</p> + </desc> + </func> + + <func> + <name name="get_module_level" arity="0"/> + <fsummary>Look up all current module levels.</fsummary> + <desc> + <p>Look up all current module levels. Returns a list + containing one <c>{Module,Level}</c> element for each module + for which the module level was previously set + with <seealso marker="#set_module_level-2"> + <c>set_module_level/2</c></seealso>.</p> + </desc> + </func> + + <func> + <name name="get_module_level" arity="1"/> + <fsummary>Look up the current level for the given modules.</fsummary> + <desc> + <p>Look up the current level for the given modules. Returns a + list containing one <c>{Module,Level}</c> element for each + of the given modules for which the module level was + previously set with <seealso marker="#set_module_level-2"> + <c>set_module_level/2</c></seealso>.</p> + </desc> + </func> + + <func> + <name name="get_process_metadata" arity="0"/> + <fsummary>Retrieve data set with set_process_metadata/1.</fsummary> + <desc> + <p>Retrieve data set + with <seealso marker="#set_process_metadata-1"> + <c>set_process_metadata/1</c></seealso> or + <seealso marker="#update_process_metadata-1"> + <c>update_process_metadata/1</c></seealso>.</p> + </desc> + </func> + + <func> + <name name="remove_handler" arity="1"/> + <fsummary>Remove the handler with the specified identity.</fsummary> + <desc> + <p>Remove the handler identified by <c><anno>HandlerId</anno></c>.</p> + </desc> + </func> + + <func> + <name name="remove_handler_filter" arity="2"/> + <fsummary>Remove a filter from the specified handler.</fsummary> + <desc> + <p>Remove the filter identified + by <c><anno>FilterId</anno></c> from the handler identified + by <c><anno>HandlerId</anno></c>.</p> + </desc> + </func> + + <func> + <name name="remove_primary_filter" arity="1"/> + <fsummary>Remove a primary filter from Logger.</fsummary> + <desc> + <p>Remove the primary filter identified + by <c><anno>FilterId</anno></c> from Logger.</p> + </desc> + </func> + + <func> + <name name="set_handler_config" arity="2"/> + <fsummary>Set configuration data for the specified handler.</fsummary> + <desc> + <p>Set configuration data for the specified handler. This + overwrites the current handler configuration.</p> + <p>To modify the existing configuration, + use <seealso marker="#update_handler_config-2"> + <c>update_handler_config/2</c></seealso>, or, if a more + complex merge is needed, read the current configuration + with <seealso marker="#get_handler_config-1"><c>get_handler_config/1</c> + </seealso>, then do the merge before writing the new + configuration back with this function.</p> + <p>If a key is removed compared to the current configuration, + and the key is known by Logger, the default value is used. If + it is a custom key, then it is up to the handler + implementation if the value is removed or a default value is + inserted.</p> + </desc> + </func> + + <func> + <name name="set_handler_config" arity="3" clause_i="1"/> + <name name="set_handler_config" arity="3" clause_i="2"/> + <name name="set_handler_config" arity="3" clause_i="3"/> + <name name="set_handler_config" arity="3" clause_i="4"/> + <name name="set_handler_config" arity="3" clause_i="5"/> + <fsummary>Add or update configuration data for the specified + handler.</fsummary> + <type variable="HandlerId"/> + <type variable="Level" name_i="1"/> + <type variable="FilterDefault" name_i="2"/> + <type variable="Filters" name_i="3"/> + <type variable="Formatter" name_i="4"/> + <type variable="Config" name_i="5"/> + <type variable="Return"/> + <desc> + <p>Add or update configuration data for the specified + handler. If the given <c><anno>Key</anno></c> already + exists, its associated value will be changed + to the given value. If it does not exist, it will + be added.</p> + <p>See the definition of + the <seealso marker="#type-handler_config"> + <c>handler_config()</c></seealso> type for more + information about the different parameters.</p> + </desc> + </func> + + <func> + <name name="set_primary_config" arity="1"/> + <fsummary>Set primary configuration data for Logger.</fsummary> + <desc> + <p>Set primary configuration data for Logger. This + overwrites the current configuration.</p> + <p>To modify the existing configuration, + use <seealso marker="#update_primary_config-1"> + <c>update_primary_config/1</c></seealso>, or, if a more + complex merge is needed, read the current configuration + with <seealso marker="#get_primary_config-0"><c>get_primary_config/0</c> + </seealso>, then do the merge before writing the new + configuration back with this function.</p> + <p>If a key is removed compared to the current configuration, + the default value is used.</p> + </desc> + </func> + + <func> + <name name="set_primary_config" arity="2" clause_i="1"/> + <name name="set_primary_config" arity="2" clause_i="2"/> + <name name="set_primary_config" arity="2" clause_i="3"/> + <fsummary>Add or update primary configuration data for Logger.</fsummary> + <type variable="Level" name_i="1"/> + <type variable="FilterDefault" name_i="2"/> + <type variable="Filters" name_i="3"/> + <desc> + <p>Add or update primary configuration data for Logger. If the + given <c><anno>Key</anno></c> already exists, its associated + value will be changed to the given value. If it does not + exist, it will be added.</p> + </desc> + </func> + + <func> + <name name="set_module_level" arity="2"/> + <fsummary>Set the log level for the specified modules.</fsummary> + <desc> + <p>Set the log level for the + specified modules.</p> + <p>The log level for a module overrides the primary log level + of Logger for log events originating from the module in + question. Notice, however, that it does not override the + level configuration for any handler.</p> + <p>For example: Assume that the primary log level for Logger + is <c>info</c>, and there is one handler, <c>h1</c>, with + level <c>info</c> and one handler, <c>h2</c>, with + level <c>debug</c>.</p> + <p>With this configuration, no debug messages will be logged, + since they are all stopped by the primary log level.</p> + <p>If the level for <c>mymodule</c> is now set + to <c>debug</c>, then debug events from this module will be + logged by the handler <c>h2</c>, but not by + handler <c>h1</c>.</p> + <p>Debug events from other modules are still not logged.</p> + <p>To change the primary log level for Logger, use + <seealso marker="#set_primary_config/2"> + <c>set_primary_config(level, Level)</c></seealso>.</p> + <p>To change the log level for a handler, use + <seealso marker="#set_handler_config/3"> + <c>set_handler_config(HandlerId, level, Level)</c> + </seealso>.</p> + <note> + <p>The originating module for a log event is only detected + if the key <c>mfa</c> exists in the metadata, and is + associated with <c>{Module, Function, Arity}</c>. When log + macros are used, this association is automatically added + to all log events. If an API function is called directly, + without using a macro, the logging client must explicitly + add this information if module levels shall have any + effect.</p> + </note> + </desc> + </func> + + <func> + <name name="set_process_metadata" arity="1"/> + <fsummary>Set metadata to use when logging from current process.</fsummary> + <desc> + <p>Set metadata which Logger shall automatically insert in + all log events produced on the current process.</p> + <p>Location data produced by the log macros, and/or metadata + given as argument to the log call (API function or macro), + are merged with the process metadata. If the same keys + occur, values from the metadata argument to the log call + overwrite values from the process metadata, which in turn + overwrite values from the location data.</p> + <p>Subsequent calls to this function overwrites previous data + set. To update existing data instead of overwriting it, + see <seealso marker="#update_process_metadata-1"> + <c>update_process_metadata/1</c></seealso>.</p> + </desc> + </func> + + <func> + <name name="unset_module_level" arity="0"/> + <fsummary>Remove module specific log settings for all modules.</fsummary> + <desc> + <p>Remove module specific log settings. After this, the + primary log level is used for all modules.</p> + </desc> + </func> + + <func> + <name name="unset_module_level" arity="1"/> + <fsummary>Remove module specific log settings for the given + modules.</fsummary> + <desc> + <p>Remove module specific log settings. After this, the + primary log level is used for the specified modules.</p> + </desc> + </func> + + <func> + <name name="unset_process_metadata" arity="0"/> + <fsummary>Delete data set with set_process_metadata/1.</fsummary> + <desc> + <p>Delete data set + with <seealso marker="#set_process_metadata-1"> + <c>set_process_metadata/1</c></seealso> or + <seealso marker="#update_process_metadata-1"> + <c>update_process_metadata/1</c></seealso>.</p> + </desc> + </func> + + <func> + <name name="update_formatter_config" arity="2"/> + <fsummary>Update the formatter configuration for the specified handler.</fsummary> + <desc> + <p>Update the formatter configuration for the specified handler.</p> + <p>The new configuration is merged with the existing formatter + configuration.</p> + <p>To overwrite the existing configuration without any merge, + use</p> + <pre> +<seealso marker="#set_handler_config-3">set_handler_config(HandlerId, formatter, + {FormatterModule, FormatterConfig})</seealso>.</pre> + </desc> + </func> + + <func> + <name name="update_formatter_config" arity="3"/> + <fsummary>Update the formatter configuration for the specified handler.</fsummary> + <desc> + <p>Update the formatter configuration for the specified handler.</p> + <p>This is equivalent to</p> + <pre> +<seealso marker="#update_formatter_config-2">update_formatter_config(<anno>HandlerId</anno>, #{<anno>Key</anno> => <anno>Value</anno>})</seealso></pre> + </desc> + </func> + + <func> + <name name="update_handler_config" arity="2"/> + <fsummary>Update configuration data for the specified handler.</fsummary> + <desc> + <p>Update configuration data for the specified handler. This function + behaves as if it was implemented as follows:</p> + <code type="erl"> +{ok, {_, Old}} = logger:get_handler_config(HandlerId), +logger:set_handler_config(HandlerId, maps:merge(Old, Config)). + </code> + <p>To overwrite the existing configuration without any merge, + use <seealso marker="#set_handler_config-2"><c>set_handler_config/2</c> + </seealso>.</p> + </desc> + </func> + + <func> + <name name="update_primary_config" arity="1"/> + <fsummary>Update primary configuration data for Logger.</fsummary> + <desc> + <p>Update primary configuration data for Logger. This function + behaves as if it was implemented as follows:</p> + <code type="erl"> +Old = logger:get_primary_config(), +logger:set_primary_config(maps:merge(Old, Config)). + </code> + <p>To overwrite the existing configuration without any merge, + use <seealso marker="#set_primary_config-1"><c>set_primary_config/1</c> + </seealso>.</p> + </desc> + </func> + + <func> + <name name="update_process_metadata" arity="1"/> + <fsummary>Set or update metadata to use when logging from + current process.</fsummary> + <desc> + <p>Set or update metadata to use when logging from current + process</p> + <p>If process metadata exists for the current process, this + function behaves as if it was implemented as follows:</p> + <code type="erl"> +logger:set_process_metadata(maps:merge(logger:get_process_metadata(), Meta)). + </code> + <p>If no process metadata exists, the function behaves as + <seealso marker="#set_process_metadata-1"> + <c>set_process_metadata/1</c> + </seealso>.</p> + </desc> + </func> + </funcs> + + <section> + <marker id="misc_API"/> + <title>Miscellaneous API functions</title> + </section> + <funcs> + <func> + <name name="compare_levels" arity="2"/> + <fsummary>Compare the severity of two log levels.</fsummary> + <desc> + <p>Compare the severity of two log levels. Returns <c>gt</c> + if <c>Level1</c> is more severe than + <c>Level2</c>, <c>lt</c> if <c>Level1</c> is less severe, + and <c>eq</c> if the levels are equal.</p> + </desc> + </func> + + <func> + <name name="format_report" arity="1"/> + <fsummary>Convert a log message on report form to {Format, Args}.</fsummary> + <desc> + <p>Convert a log message on report form to <c>{Format, + Args}</c>. This is the default report callback used + by <seealso marker="logger_formatter"> + <c>logger_formatter</c></seealso> when no custom report + callback is found. See + section <seealso marker="logger_chapter#log_message">Log + Message</seealso> in the Kernel User's Guide for + information about report callbacks and valid forms of log + messages.</p> + <p>The function produces lines of <c>Key: Value</c> from + key-value lists. Strings are printed with <c>~ts</c> and + other terms with <c>~tp</c>.</p> + <p>If <c><anno>Report</anno></c> is a map, it is converted to + a key-value list before formatting as such.</p> + </desc> + </func> + </funcs> + + <section> + <marker id="handler_callback_functions"/> + <title>Handler Callback Functions</title> + <p>The following functions are to be exported from a handler + callback module.</p> + </section> + + <funcs> + <func> + <name>HModule:adding_handler(Config1) -> {ok, Config2} | {error, + Reason}</name> + <fsummary>An instance of this handler is about to be added.</fsummary> + <type> + <v>Config1 = Config2 = + <seealso marker="#type-handler_config">handler_config()</seealso></v> + <v>Reason = term()</v> + </type> + <desc> + <p>This callback function is optional.</p> + <p>The function is called on a temporary process when an new + handler is about to be added. The purpose is to verify the + configuration and initiate all resources needed by the + handler.</p> + <p>The handler identity is associated with the <c>id</c> key + in <c>Config1</c>.</p> + <p>If everything succeeds, the callback function can add + possible default values or internal state values to the + configuration, and return the adjusted map + in <c>{ok,Config2}</c>.</p> + <p>If the configuration is faulty, or if the initiation fails, + the callback function must return <c>{error,Reason}</c>.</p> + </desc> + </func> + + <func> + <name>HModule:changing_config(Config1, Config2) -> {ok, Config3} | {error, Reason}</name> + <fsummary>The configuration for this handler is about to change.</fsummary> + <type> + <v>Config1 = Config2 = Config3 = + <seealso marker="#type-handler_config">handler_config()</seealso></v> + <v>Reason = term()</v> + </type> + <desc> + <p>This callback function is optional.</p> + <p>The function is called on a temporary process when the + configuration for a handler is about to change. The purpose + is to verify and act on the new configuration.</p> + <p><c>Config1</c> is the existing configuration + and <c>Config2</c> is the new configuration.</p> + <p>The handler identity is associated with the <c>id</c> key + in <c>Config1</c>.</p> + <p>If everything succeeds, the callback function must return a + possibly adjusted configuration in <c>{ok,Config3}</c>.</p> + <p>If the configuration is faulty, the callback function must + return <c>{error,Reason}</c>.</p> + </desc> + </func> + + <func> + <name>HModule:log(LogEvent, Config) -> void()</name> + <fsummary>Log the given log event.</fsummary> + <type> + <v>LogEvent = + <seealso marker="#type-log_event">log_event()</seealso></v> + <v>Config = + <seealso marker="#type-handler_config">handler_config()</seealso></v> + </type> + <desc> + <p>This callback function is mandatory.</p> + <p>The function is called when all primary filters and all + handler filters for the handler in question have passed for + the given log event. It is called on the client process, that + is, the process that issued the log event.</p> + <p>The handler identity is associated with the <c>id</c> key + in <c>Config</c>.</p> + <p>The handler must log the event.</p> + <p>The return value from this function is ignored by + Logger.</p> + </desc> + </func> + + <func> + <name>HModule:removing_handler(Config) -> ok</name> + <fsummary>The given handler is about to be removed.</fsummary> + <type> + <v>Config = + <seealso marker="#type-handler_config">handler_config()</seealso></v> + </type> + <desc> + <p>This callback function is optional.</p> + <p>The function is called on a temporary process when a + handler is about to be removed. The purpose is to release + all resources used by the handler.</p> + <p>The handler identity is associated with the <c>id</c> key + in <c>Config</c>.</p> + <p>The return value is ignored by Logger.</p> + </desc> + </func> + + </funcs> + + <section> + <marker id="formatter_callback_functions"/> + <title>Formatter Callback Functions</title> + <p>The following functions are to be exported from a formatter + callback module.</p> + </section> + + <funcs> + <func> + <name>FModule:check_config(FConfig) -> ok | {error, Reason}</name> + <fsummary>Validate the given formatter configuration.</fsummary> + <type> + <v>FConfig = + <seealso marker="#type-formatter_config">formatter_config()</seealso></v> + <v>Reason = term()</v> + </type> + <desc> + <p>This callback function is optional.</p> + <p>The function is called by a Logger when formatter + configuration is set or modified. The formatter must + validate the given configuration and return <c>ok</c> if it + is correct, and <c>{error,Reason}</c> if it is faulty.</p> + <p>The following Logger API functions can trigger this callback:</p> + <list> + <item><seealso marker="logger#add_handler-3"> + <c>logger:add_handler/3</c></seealso></item> + <item><seealso marker="logger#set_handler_config-2"> + <c>logger:set_handler_config/2,3</c></seealso></item> + <item><seealso marker="logger#update_handler_config-2"> + <c>logger:updata_handler_config/2</c></seealso></item> + <item><seealso marker="logger#update_formatter_config-2"> + <c>logger:update_formatter_config/2</c></seealso></item> + </list> + <p>See <seealso marker="logger_formatter"> + <c>logger_formatter(3)</c></seealso> + for an example implementation. <c>logger_formatter</c> is the + default formatter used by Logger.</p> + </desc> + </func> + <func> + <name>FModule:format(LogEvent, FConfig) -> FormattedLogEntry</name> + <fsummary>Format the given log event.</fsummary> + <type> + <v>LogEvent = + <seealso marker="#type-log_event">log_event()</seealso></v> + <v>FConfig = + <seealso marker="#type-formatter_config">formatter_config()</seealso></v> + <v>FormattedLogEntry = + <seealso marker="unicode#type-chardata">unicode:chardata()</seealso></v> + </type> + <desc> + <p>This callback function is mandatory.</p> + <p>The function can be called by a log handler to convert a + log event term to a printable string. The returned value + can, for example, be printed as a log entry to the console + or a file using <seealso marker="stdlib:io#put_chars-1"> + <c>io:put_chars/1,2</c></seealso>.</p> + <p>See <seealso marker="logger_formatter"> + <c>logger_formatter(3)</c></seealso> + for an example implementation. <c>logger_formatter</c> is the + default formatter used by Logger.</p> + </desc> + </func> + </funcs> + + <section> + <title>See Also</title> + <p> + <seealso marker="config"><c>config(4)</c></seealso>, + <seealso marker="erts:erlang"><c>erlang(3)</c></seealso>, + <seealso marker="stdlib:io"><c>io(3)</c></seealso>, + <seealso marker="logger_disk_log_h"><c>logger_disk_log_h(3)</c></seealso>, + <seealso marker="logger_filters"><c>logger_filters(3)</c></seealso>, + <seealso marker="logger_formatter"><c>logger_formatter(3)</c></seealso>, + <seealso marker="logger_std_h"><c>logger_std_h(3)</c></seealso>, + <seealso marker="stdlib:unicode"><c>unicode(3)</c></seealso> + </p> + </section> +</erlref> + + diff --git a/lib/kernel/doc/src/logger_arch.dia b/lib/kernel/doc/src/logger_arch.dia Binary files differnew file mode 100644 index 0000000000..97be31856e --- /dev/null +++ b/lib/kernel/doc/src/logger_arch.dia diff --git a/lib/kernel/doc/src/logger_arch.png b/lib/kernel/doc/src/logger_arch.png Binary files differnew file mode 100644 index 0000000000..70933a5a41 --- /dev/null +++ b/lib/kernel/doc/src/logger_arch.png diff --git a/lib/kernel/doc/src/logger_chapter.xml b/lib/kernel/doc/src/logger_chapter.xml new file mode 100644 index 0000000000..30172f6ca6 --- /dev/null +++ b/lib/kernel/doc/src/logger_chapter.xml @@ -0,0 +1,1331 @@ +<?xml version="1.0" encoding="utf-8" ?> +<!DOCTYPE chapter SYSTEM "chapter.dtd"> + +<chapter> + <header> + <copyright> + <year>2017</year><year>2018</year> + <holder>Ericsson AB. All Rights Reserved.</holder> + </copyright> + <legalnotice> + Licensed under the Apache License, Version 2.0 (the "License"); + you may not use this file except in compliance with the License. + You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + + Unless required by applicable law or agreed to in writing, software + distributed under the License is distributed on an "AS IS" BASIS, + WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + See the License for the specific language governing permissions and + limitations under the License. + + </legalnotice> + + <title>Logging</title> + <prepared></prepared> + <docno></docno> + <date></date> + <rev></rev> + <file>logger_chapter.xml</file> + </header> + + <p>Erlang/OTP 21.0 provides a standard API for logging + through <c>Logger</c>, which is part of the Kernel + application. Logger consists of the API for issuing log events, + and a customizable backend where log handlers, filters and + formatters can be plugged in.</p> + <p>By default, the Kernel application installs one log handler at + system start. This handler is named <c>default</c>. It receives + and processes standard log events produced by the Erlang runtime + system, standard behaviours and different Erlang/OTP + applications. The log events are by default written to the + terminal.</p> + <p>You can also configure the system so that the default handler + prints log events to a single file, or to a set of wrap logs + via <seealso marker="disk_log"><c>disk_log</c></seealso>.</p> + <p>By configuration, you can also modify or disable the default + handler, replace it by a custom handler, and install additional + handlers.</p> + + <note> + <p>Since Logger is new in Erlang/OTP 21.0, we do reserve the right + to introduce changes to the Logger API and functionality in + patches following this release. These changes might or might not + be backwards compatible with the initial version.</p> + </note> + + <section> + <title>Overview</title> + <p>A <em>log event</em> consists of a <em>log level</em>, the + <em>message</em> to be logged, and <em>metadata</em>.</p> + <p>The Logger backend forwards log events from the API, first + through a set of <em>primary filters</em>, then through a set of + secondary filters attached to each log handler. The secondary + filters are in the following named <em>handler filters</em>.</p> + <p>Each filter set consists of a <em>log level check</em>, + followed by zero or more <em>filter functions</em>.</p> + <p>The following figure shows a conceptual overview of Logger. The + figure shows two log handlers, but any number of handlers can be + installed.</p> + + <!-- The image is edited with dia in logger_arch.dia file, + and .png file generated with make target 'png'. --> + <image file="logger_arch.png"> + <icaption>Conceptual Overview</icaption> + </image> + + <p>Log levels are expressed as atoms. Internally in Logger, the + atoms are mapped to integer values, and a log event passes the + log level check if the integer value of its log level is less + than or equal to the currently configured log level. That is, + the check passes if the event is equally or more severe than the + configured level. See section <seealso marker="#log_level">Log + Level</seealso> for a listing and description of all log + levels.</p> + <p>The primary log level can be overridden by a log level + configured per module. This is to, for instance, allow more + verbose logging from a specific part of the system.</p> + <p>Filter functions can be used for more sophisticated filtering + than the log level check provides. A filter function can stop or + pass a log event, based on any of the event's contents. It can + also modify all parts of the log event. See see + section <seealso marker="#filters">Filters</seealso> for more + details.</p> + <p>If a log event passes through all primary filters and all + handler filters for a specific handler, Logger forwards the + event to the <em>handler callback</em>. The handler formats and + prints the event to its destination. See + section <seealso marker="#handlers">Handlers</seealso> for more + details.</p> + <p>Everything up to and including the call to the handler + callbacks is executed on the client process, that is, the + process where the log event was issued. It is up to the handler + implementation if other processes are involved or not.</p> + <p>The handlers are called in sequence, and the order is not + defined.</p> + </section> + <section> + <marker id="logger_api"/> + <title>Logger API</title> + <p>The API for logging consists of a set + of <seealso marker="logger#macros">macros</seealso>, and a set + of functions on the form <c>logger:Level/1,2,3</c>, which are + all shortcuts + for <seealso marker="logger#log-2"> + <c>logger:log(Level,Arg1[,Arg2[,Arg3]])</c></seealso>.</p> + <p>The difference between using the macros and the exported + functions is that macros add location (originator) information + to the metadata, and performs lazy evaluation by wrapping the + logger call in a case statement, so it is only evaluated if the + log level of the event passes the primary log level check.</p> + <section> + <marker id="log_level"/> + <title>Log Level</title> + <p>The log level indicates the severity of a event. In + accordance with the Syslog protocol, + <url href="https://www.ietf.org/rfc/rfc5424.txt">RFC + 5424</url>, eight log levels can be specified. The following + table lists all possible log levels by name (atom), integer + value, and description:</p> + + <table align="left"> + <row> + <cell><strong>Level</strong></cell> + <cell align="center"><strong>Integer</strong></cell> + <cell><strong>Description</strong></cell> + </row> + <row> + <cell>emergency</cell> + <cell align="center">0</cell> + <cell>system is unusable</cell> + </row> + <row> + <cell>alert</cell> + <cell align="center">1</cell> + <cell>action must be taken immediately</cell> + </row> + <row> + <cell>critical</cell> + <cell align="center">2</cell> + <cell>critical conditions</cell> + </row> + <row> + <cell>error</cell> + <cell align="center">3</cell> + <cell>error conditions</cell> + </row> + <row> + <cell>warning</cell> + <cell align="center">4</cell> + <cell>warning conditions</cell> + </row> + <row> + <cell>notice</cell> + <cell align="center">5</cell> + <cell>normal but significant conditions</cell> + </row> + <row> + <cell>info</cell> + <cell align="center">6</cell> + <cell>informational messages</cell> + </row> + <row> + <cell>debug</cell> + <cell align="center">7</cell> + <cell>debug-level messages</cell> + </row> + <tcaption>Log Levels</tcaption> + </table> + <p>Notice that the integer value is only used internally in + Logger. In the API, you must always use the atom. To compare + the severity of two log levels, + use <seealso marker="logger#compare_levels-2"> + <c>logger:compare_levels/2</c></seealso>.</p> + </section> + <section> + <marker id="log_message"/> + <title>Log Message</title> + <p>The log message contains the information to be logged. The + message can consist of a format string and arguments (given as + two separate parameters in the Logger API), a string or a + report. The latter, which is either a map or a key-value list, + can be accompanied by a <em>report callback</em> specified in + the log event's <seealso marker="#metadata">metadata</seealso>. + The report callback is a convenience function that + the <seealso marker="#formatters">formatter</seealso> can use + to convert the report to a format string and arguments, or + directly to a string. The + formatter can also use its own conversion function, if no + callback is provided, or if a customized formatting is + desired.</p> + <p>The report callback must be a fun with one or two + arguments. If it takes one argument, this is the report + itself, and the fun returns a format string and arguments:</p> + <pre>fun((<seealso marker="logger#type-report"><c>logger:report()</c></seealso>) -> {<seealso marker="stdlib:io#type-format"><c>io:format()</c></seealso>,[term()]})</pre> + <p>If it takes two arguments, the first is the report, and the + second is a map containing extra data that allows direct + coversion to a string:</p> + <pre>fun((<seealso marker="logger#type-report"><c>logger:report()</c></seealso>,<seealso marker="logger#type-report_cb_config"><c>logger:report_cb_config()</c></seealso>) -> <seealso marker="stdlib:unicode#type-chardata"><c>unicode:chardata()</c></seealso>) + </pre> + <p>The fun must obey the <c>encoding</c>, <c>depth</c> + and <c>chars_limit</c> parameters provided in the second + argument, as the formatter can not do anything useful of these + parameters with the returned string. This variant is used when + the formatting of the report depends on the size and encoding + parameters.</p> + <p>Example, format string and arguments:</p> + <code>logger:error("The file does not exist: ~ts",[Filename])</code> + <p>Example, string:</p> + <code>logger:notice("Something strange happened!")</code> + <p>Example, report, and metadata with report callback:</p> + <code> +logger:debug(#{got => connection_request, id => Id, state => State}, + #{report_cb => fun(R) -> {"~p",[R]} end})</code> + <p>The log message can also be provided through a fun for lazy + evaluation. The fun is only evaluated if the primary log level + check passes, and is therefore recommended if it is expensive + to generate the message. The lazy fun must return a string, a + report, or a tuple with format string and arguments.</p> + </section> + <section> + <title>Metadata</title> + <p>Metadata contains additional data associated with a log + message. Logger inserts some metadata fields by default, and + the client can add custom metadata in two different ways:</p> + <taglist> + <tag>Set process metadata</tag> + <item> + <p>Process metadata is set and updated + with <seealso marker="logger#set_process_metadata-1"> + <c>logger:set_process_metadata/1</c></seealso> + and <seealso marker="logger#update_process_metadata-1"> + <c>logger:update_process_metadata/1</c></seealso>, + respectively. This metadata applies to the process on + which these calls are made, and Logger adds the metadata + to all log events issued on that process.</p> + </item> + <tag>Add metadata to a specific log event</tag> + <item> + <p>Metadata associated with one specific log event is given + as the last parameter to the log macro or Logger API + function when the event is issued. For example:</p> + <code>?LOG_ERROR("Connection closed",#{context => server})</code> + </item> + </taglist> + <p>See the description of + the <seealso marker="logger#type-metadata"> + <c>logger:metadata()</c></seealso> type for information + about which default keys Logger inserts, and how the different + metadata maps are merged.</p> + </section> + </section> + <section> + <marker id="filter"/> + <title>Filters</title> + <p>Filters can be primary, or attached to a specific + handler. Logger calls the primary filters first, and if they all + pass, it calls the handler filters for each handler. Logger + calls the handler callback only if all filters attached to the + handler in question also pass.</p> + <p>A filter is defined as:</p> + <pre>{FilterFun, Extra}</pre> + <p>where <c>FilterFun</c> is a function of arity 2, + and <c>Extra</c> is any term. When applying the filter, Logger + calls the function with the log event as the first argument, + and the value of <c>Extra</c> as the second + argument. See <seealso marker="logger#type-filter"> + <c>logger:filter()</c></seealso> for type definitions.</p> + <p>The filter function can return <c>stop</c>, <c>ignore</c> or + the (possibly modified) log event.</p> + <p>If <c>stop</c> is returned, the log event is immediately + discarded. If the filter is primary, no handler filters or + callbacks are called. If it is a handler filter, the + corresponding handler callback is not called, but the log event + is forwarded to filters attached to the next handler, if + any.</p> + <p>If the log event is returned, the next filter function is + called with the returned value as the first argument. That is, + if a filter function modifies the log event, the next filter + function receives the modified event. The value returned from + the last filter function is the value that the handler callback + receives.</p> + <p>If the filter function returns <c>ignore</c>, it means that it + did not recognize the log event, and thus leaves to other + filters to decide the event's destiny.</p> + <p>The configuration option <c>filter_default</c> specifies the + behaviour if all filter functions return <c>ignore</c>, or if no + filters exist. <c>filter_default</c> is by default set + to <c>log</c>, meaning that if all existing filters ignore a log + event, Logger forwards the event to the handler + callback. If <c>filter_default</c> is set to <c>stop</c>, Logger + discards such events.</p> + <p>Primary filters are added + with <seealso marker="logger#add_primary_filter-2"> + <c>logger:add_primary_filter/2</c></seealso> + and removed + with <seealso marker="logger#remove_primary_filter-1"> + <c>logger:remove_primary_filter/1</c></seealso>. They can also + be added at system start via the Kernel configuration + parameter <seealso marker="#logger_parameter"><c>logger</c></seealso>.</p> + <p>Handler filters are added + with <seealso marker="logger#add_handler_filter-3"> + <c>logger:add_handler_filter/3</c></seealso> + and removed + with <seealso marker="logger#remove_handler_filter-2"> + <c>logger:remove_handler_filter/2</c></seealso>. They can also + be specified directly in the configuration when adding a handler + with <seealso marker="logger#add_handler/3"> + <c>logger:add_handler/3</c></seealso> + or via the Kernel configuration + parameter <seealso marker="#logger_parameter"><c>logger</c></seealso>.</p> + + <p>To see which filters are currently installed in the system, + use <seealso marker="logger#get_config-0"> + <c>logger:get_config/0</c></seealso>, + or <seealso marker="logger#get_primary_config-0"> + <c>logger:get_primary_config/0</c></seealso> + and <seealso marker="logger#get_handler_config-1"> + <c>logger:get_handler_config/1</c></seealso>. Filters are + listed in the order they are applied, that is, the first + filter in the list is applied first, and so on.</p> + + <p>For convenience, the following built-in filters exist:</p> + + <taglist> + <tag><seealso marker="logger_filters#domain-2"> + <c>logger_filters:domain/2</c></seealso></tag> + <item> + <p>Provides a way of filtering log events based on a + <c>domain</c> field in <c>Metadata</c>.</p> + </item> + <tag><seealso marker="logger_filters#level-2"> + <c>logger_filters:level/2</c></seealso></tag> + <item> + <p>Provides a way of filtering log events based on the log + level.</p> + </item> + <tag><seealso marker="logger_filters#progress-2"> + <c>logger_filters:progress/2</c></seealso></tag> + <item> + <p>Stops or allows progress reports from <c>supervisor</c> + and <c>application_controller</c>.</p> + </item> + <tag><seealso marker="logger_filters#remote_gl-2"> + <c>logger_filters:remote_gl/2</c></seealso></tag> + <item> + <p>Stops or allows log events originating from a process + that has its group leader on a remote node.</p> + </item> + </taglist> + </section> + + <section> + <marker id="handlers"/> + <title>Handlers</title> + <p>A handler is defined as a module exporting at least the + following callback function:</p> + + <pre><seealso marker="logger#HModule:log-2">log(LogEvent, Config) -> void()</seealso></pre> + + <p>This function is called when a log event has passed through all + primary filters, and all handler filters attached to the handler + in question. The function call is executed on the client + process, and it is up to the handler implementation if other + processes are involved or not.</p> + + <p>Logger allows adding multiple instances of a handler + callback. That is, if a callback module implementation allows + it, you can add multiple handler instances using the same + callback module. The different instances are identified by + unique handler identities.</p> + + <p>In addition to the mandatory callback function <c>log/2</c>, a + handler module can export the optional callback + functions <c>adding_handler/1</c>, <c>changing_config/2</c> + and <c>removing_handler/1</c>. See + section <seealso marker="logger#handler_callback_functions">Handler + Callback Functions</seealso> in the logger(3) manual page for + more information about these function.</p> + + <p>The following built-in handlers exist:</p> + + <taglist> + <tag><c>logger_std_h</c></tag> + <item> + <p>This is the default handler used by OTP. Multiple instances + can be started, and each instance will write log events to a + given destination, terminal or file.</p> + </item> + + <tag><c>logger_disk_log_h</c></tag> + <item> + <p>This handler behaves much like <c>logger_std_h</c>, except it uses + <seealso marker="disk_log"><c>disk_log</c></seealso> as its + destination.</p> + </item> + + <tag><marker id="ErrorLoggerManager"/><c>error_logger</c></tag> + <item> + <p>This handler is provided for backwards compatibility + only. It is not started by default, but will be + automatically started the first time an <c>error_logger</c> + event handler is added + with <seealso marker="error_logger#add_report_handler-1"> + <c>error_logger:add_report_handler/1,2</c></seealso>.</p> + + <p>The old <c>error_logger</c> event handlers in STDLIB and + SASL still exist, but they are not added by Erlang/OTP 21.0 + or later.</p> + </item> + </taglist> + </section> + + <section> + <marker id="formatters"/> + <title>Formatters</title> + <p>A formatter can be used by the handler implementation to do the + final formatting of a log event, before printing to the + handler's destination. The handler callback receives the + formatter information as part of the handler configuration, + which is passed as the second argument + to <seealso marker="logger#HModule:log-2"> + <c>HModule:log/2</c></seealso>.</p> + <p>The formatter information consist of a formatter + module, <c>FModule</c> and its + configuration, <c>FConfig</c>. <c>FModule</c> must export the + following function, which can be called by the handler:</p> + <pre><seealso marker="logger#FModule:format-2">format(LogEvent,FConfig) + -> FormattedLogEntry</seealso></pre> + <p>The formatter information for a handler is set as a part of its + configuration when the handler is added. It can also be changed + during runtime + with <seealso marker="logger#set_handler_config-3"> + <c>logger:set_handler_config(HandlerId,formatter,{FModule,FConfig})</c> + </seealso>, which overwrites the current formatter information, + or with <seealso marker="logger#update_formatter_config-2"> + <c>logger:update_formatter_config/2,3</c></seealso>, which + only modifies the formatter configuration.</p> + <p>If the formatter module exports the optional callback + function <seealso marker="logger#FModule:check_config-1"> + <c>check_config(FConfig)</c></seealso>, Logger calls this + function when the formatter information is set or modified, to + verify the validity of the formatter configuration.</p> + <p>If no formatter information is specified for a handler, Logger + uses <c>logger_formatter</c> as default. See + the <seealso marker="logger_formatter"><c>logger_formatter(3)</c></seealso> + manual page for more information about this module.</p> + </section> + + <section> + <title>Configuration</title> + + <p>At system start, Logger is configured through Kernel + configuration parameters. The parameters that apply to Logger + are described in + section <seealso marker="#kernel_config_params">Kernel + Configuration Parameters</seealso>. Examples are found in + section <seealso marker="#config_examples">Configuration + Examples</seealso>.</p> + <p>During runtime, Logger configuration is changed via API + functions. See + section <seealso marker="logger#configuration_API">Configuration + API Functions</seealso> in the <c>logger(3)</c> manual page.</p> + + <section> + <title>Primary Logger Configuration</title> + <p>Logger API functions that apply to the primary Logger + configuration are:</p> + <list> + <item><seealso marker="logger#get_primary_config-0"> + <c>get_primary_config/0</c></seealso></item> + <item><seealso marker="logger#set_primary_config-1"> + <c>set_primary_config/1,2</c></seealso></item> + <item><seealso marker="logger#update_primary_config-1"> + <c>update_primary_config/1</c></seealso></item> + <item><seealso marker="logger#add_primary_filter-2"> + <c>add_primary_filter/2</c></seealso></item> + <item><seealso marker="logger#remove_primary_filter-1"> + <c>remove_primary_filter/1</c></seealso></item> + </list> + <p>The primary Logger configuration is a map with the following + keys:</p> + <taglist> + <tag><marker id="primary_level"/> + <c>level = </c><seealso marker="logger#type-level"> + <c>logger:level()</c></seealso><c> | all | none</c></tag> + <item> + <p>Specifies the primary log level, that is, log event that + are equally or more severe than this level, are forwarded + to the primary filters. Less severe log events are + immediately discarded.</p> + <p>See section <seealso marker="#log_level">Log + Level</seealso> for a listing and description of + possible log levels.</p> + <p>The initial value of this option is set by the Kernel + configuration parameter <seealso marker="#logger_level"> + <c>logger_level</c></seealso>. It is changed during + runtime with <seealso marker="logger#set_primary_config-2"> + <c>logger:set_primary_config(level,Level)</c></seealso>.</p> + <p>Defaults to <c>info</c>.</p> + </item> + <tag><c>filters = [{FilterId,Filter}]</c></tag> + <item> + <p>Specifies the primary filters.</p> + <list> + <item><c>FilterId = </c><seealso marker="logger#type-filter_id"> + <c>logger:filter_id()</c></seealso></item> + <item><c>Filter = </c><seealso marker="logger#type-filter"> + <c>logger:filter()</c></seealso></item> + </list> + <p>The initial value of this option is set by the Kernel + configuration + parameter <seealso marker="#logger_parameter"><c>logger</c></seealso>. + During runtime, primary filters are added and removed with + <seealso marker="logger#add_primary_filter-2"> + <c>logger:add_primary_filter/2</c></seealso> and + <seealso marker="logger#remove_primary_filter-1"> + <c>logger:remove_primary_filter/1</c></seealso>, + respectively.</p> + <p>See section <seealso marker="#filters">Filters</seealso> + for more detailed information.</p> + <p>Defaults to <c>[]</c>.</p> + </item> + <tag><c>filter_default = log | stop</c></tag> + <item> + <p>Specifies what happens to a log event if all filters + return <c>ignore</c>, or if no filters exist.</p> + <p>See section <seealso marker="#filters">Filters</seealso> + for more information about how this option is used.</p> + <p>Defaults to <c>log</c>.</p> + </item> + </taglist> + </section> + + <section> + <marker id="handler_configuration"/> + <title>Handler Configuration</title> + <p>Logger API functions that apply to handler configuration + are:</p> + <list> + <item><seealso marker="logger#get_handler_config-0"> + <c>get_handler_config/0,1</c></seealso></item> + <item><seealso marker="logger#set_handler_config-2"> + <c>set_handler_config/2,3</c></seealso></item> + <item><seealso marker="logger#update_handler_config-2"> + <c>update_handler_config/2</c></seealso></item> + <item><seealso marker="logger#add_handler_filter-3"> + <c>add_handler_filter/3</c></seealso></item> + <item><seealso marker="logger#remove_handler_filter-2"> + <c>remove_handler_filter/2</c></seealso></item> + <item><seealso marker="logger#update_formatter_config-2"> + <c>update_formatter_config/2,3</c></seealso></item> + </list> + <p>The configuration for a handler is a map with the following keys:</p> + <taglist> + <tag><c>id = </c><seealso marker="logger#type-handler_id"> + <c>logger:handler_id()</c></seealso></tag> + <item> + <p>Automatically inserted by Logger. The value is the same + as the <c>HandlerId</c> specified when adding the handler, + and it cannot be changed.</p> + </item> + <tag><c>module = module()</c></tag> + <item> + <p>Automatically inserted by Logger. The value is the same + as the <c>Module</c> specified when adding the handler, + and it cannot be changed.</p> + </item> + <tag><c>level = </c><seealso marker="logger#type-level"> + <c>logger:level()</c></seealso><c> | all | none</c></tag> + <item> + <p>Specifies the log level for the handler, that is, log + events that are equally or more severe than this level, + are forwarded to the handler filters for this + handler.</p> + <p>See section <seealso marker="#log_level">Log + Level</seealso> for a listing and description of + possible log levels.</p> + <p>The log level is specified when adding the handler, or + changed during runtime with, for + instance, <seealso marker="logger#set_handler_config/3"> + <c>logger:set_handler_config(HandlerId,level,Level)</c></seealso>. + </p> + <p>Defaults to <c>all</c>.</p> + </item> + <tag><c>filters = [{FilterId,Filter}]</c></tag> + <item> + <p>Specifies the handler filters.</p> + <list> + <item><c>FilterId = </c><seealso marker="logger#type-filter_id"> + <c>logger:filter_id()</c></seealso></item> + <item><c>Filter = </c><seealso marker="logger#type-filter"> + <c>logger:filter()</c></seealso></item> + </list> + <p>Handler filters are specified when adding the handler, + or added or removed during runtime with + <seealso marker="logger#add_handler_filter-3"> + <c>logger:add_handler_filter/3</c></seealso> and + <seealso marker="logger#remove_handler_filter-2"> + <c>logger:remove_handler_filter/2</c></seealso>, + respectively.</p> + <p>See <seealso marker="#filters">Filters</seealso> for more + detailed information.</p> + <p>Defaults to <c>[]</c>.</p> + </item> + <tag><c>filter_default = log | stop</c></tag> + <item> + <p>Specifies what happens to a log event if all filters + return <c>ignore</c>, or if no filters exist.</p> + <p>See section <seealso marker="#filters">Filters</seealso> + for more information about how this option is used.</p> + <p>Defaults to <c>log</c>.</p> + </item> + <tag><c>formatter = {FormatterModule,FormatterConfig}</c></tag> + <item> + <p>Specifies a formatter that the handler can use for + converting the log event term to a printable string.</p> + <list> + <item><c>FormatterModule = module()</c></item> + <item><c>FormatterConfig = </c> + <seealso marker="logger#type-formatter_config"> + <c>logger:formatter_config()</c></seealso></item> + </list> + <p>The formatter information is specified when adding the + handler. The formatter configuration can be changed during + runtime + with <seealso marker="logger#update_formatter_config-2"> + <c>logger:update_formatter_config/2,3</c></seealso>, + or the complete formatter information can be overwritten + with, for + instance, <seealso marker="logger#set_handler_config-3"> + <c>logger:set_handler_config/3</c></seealso>.</p> + <p>See + section <seealso marker="#formatters">Formatters</seealso> + for more detailed information.</p> + <p>Defaults + to <c>{logger_formatter,DefaultFormatterConfig}</c>. See + the <seealso marker="logger_formatter"> + <c>logger_formatter(3)</c></seealso> manual page for + information about this formatter and its default + configuration.</p> + </item> + <tag><c>config = term()</c></tag> + <item> + <p>Handler specific configuration, that is, configuration + data related to a specific handler implementation.</p> + <p>The configuration for the built-in handlers is described + in + the <seealso marker="logger_std_h"><c>logger_std_h(3)</c></seealso> + and + <seealso marker="logger_disk_log_h"><c>logger_disk_log_h(3)</c> + </seealso> manual pages.</p> + </item> + </taglist> + + <p>Notice that <c>level</c> and <c>filters</c> are obeyed by + Logger itself before forwarding the log events to each + handler, while <c>formatter</c> and all handler specific + options are left to the handler implementation.</p> + </section> + + <section> + <marker id="kernel_config_params"/> + <title>Kernel Configuration Parameters</title> + + <p>The following Kernel configuration parameters apply to + Logger:</p> + <taglist> + <tag><marker id="logger_parameter"/><c>logger = [Config]</c></tag> + <item> + <p>Specifies the configuration + for <seealso marker="logger">Logger</seealso>, except the + primary log level, which is specified + with <seealso marker="#logger_level"><c>logger_level</c></seealso>, + and the compatibility + with <seealso marker="sasl:error_logging">SASL Error + Logging</seealso>, which is specified + with <seealso marker="#logger_sasl_compatible"> + <c>logger_sasl_compatible</c></seealso>.</p> + <p>With this parameter, you can modify or disable the default + handler, add custom handlers and primary logger filters, and + set log levels per module.</p> + <p><c>Config</c> is any (zero or more) of the following:</p> + <taglist> + <tag><c>{handler, default, undefined}</c></tag> + <item> + <p>Disables the default handler. This allows another + application to add its own default handler.</p> + <p>Only one entry of this type is allowed.</p> + </item> + <tag><c>{handler, HandlerId, Module, HandlerConfig}</c></tag> + <item> + <p>If <c>HandlerId</c> is <c>default</c>, then this entry + modifies the default handler, equivalent to calling</p> + <pre><seealso marker="logger#set_handler_config-2"> + logger:set_handler_config(default, Module, HandlerConfig) + </seealso></pre> + <p>For all other values of <c>HandlerId</c>, this entry + adds a new handler, equivalent to calling</p> + <pre><seealso marker="logger:add_handler/3"> + logger:add_handler(HandlerId, Module, HandlerConfig) + </seealso></pre> + <p>Multiple entries of this type are allowed.</p></item> + <tag><c>{filters, FilterDefault, [Filter]}</c></tag> + <item> + <p>Adds the specified primary filters.</p> + <list> + <item><c>FilterDefault = log | stop</c></item> + <item><c>Filter = {FilterId, {FilterFun, FilterConfig}}</c></item> + </list> + <p>Equivalent to calling</p> + <pre><seealso marker="logger#add_primary_filter/2"> + logger:add_primary_filter(FilterId, {FilterFun, FilterConfig}) + </seealso></pre> + <p>for each <c>Filter</c>.</p> + <p><c>FilterDefault</c> specifies the behaviour if all + primary filters return <c>ignore</c>, see + section <seealso marker="#filters">Filters</seealso>.</p> + <p>Only one entry of this type is allowed.</p> + </item> + <tag><c>{module_level, Level, [Module]}</c></tag> + <item> + <p>Sets module log level for the given modules. Equivalent + to calling</p> + <pre><seealso marker="logger#set_module_level/2"> + logger:set_module_level(Module, Level)</seealso></pre> + <p>for each <c>Module</c>.</p> + <p>Multiple entries of this type are allowed.</p> + </item> + </taglist> + <p>See + section <seealso marker="#config_examples">Configuration + Examples</seealso> for examples using the <c>logger</c> + parameter for system configuration.</p> + </item> + <tag><marker id="logger_level"/> + <c>logger_level = Level</c></tag> + <item> + <p>Specifies the primary log level. See + the <seealso marker="kernel_app#logger_level"><c>kernel(6)</c></seealso> + manual page for more information about this parameter.</p> + </item> + <tag><marker id="logger_sasl_compatible"/> + <c>logger_sasl_compatible = true | false</c></tag> + <item> + <p>Specifies Logger's compatibility + with <seealso marker="sasl:error_logging">SASL Error + Logging</seealso>. See + the <seealso marker="kernel_app#logger_sasl_compatible"> + <c>kernel(6)</c></seealso> manual page for more + information about this parameter.</p> + </item> + </taglist> + </section> + + <section> + <marker id="config_examples"/> + <title>Configuration Examples</title> + <p>The value of the Kernel configuration parameter <c>logger</c> + is a list of tuples. It is possible to write the term on the + command line when starting an erlang node, but as the term + grows, a better approach is to use the system configuration + file. See + the <seealso marker="config"><c>config(4)</c></seealso> manual + page for more information about this file.</p> + <p>Each of the following examples shows a simple system + configuration file that configures Logger according to the + description.</p> + <p>Modify the default handler to print to a file instead of + <c>standard_io</c>:</p> + <code> +[{kernel, + [{logger, + [{handler, default, logger_std_h, % {handler, HandlerId, Module, + #{config => #{type => {file,"log/erlang.log"}}}} % Config} + ]}]}]. + </code> + <p>Modify the default handler to print each log event as a + single line:</p> + <code> +[{kernel, + [{logger, + [{handler, default, logger_std_h, + #{formatter => {logger_formatter, #{single_line => true}}}} + ]}]}]. + </code> + <p>Modify the default handler to print the pid of the logging + process for each log event:</p> + <code> +[{kernel, + [{logger, + [{handler, default, logger_std_h, + #{formatter => {logger_formatter, + #{template => [time," ",pid," ",msg,"\n"]}}}} + ]}]}]. + </code> + <p>Modify the default handler to only print errors and more + severe log events to "log/erlang.log", and add another handler + to print all log events to "log/debug.log".</p> + <code> +[{kernel, + [{logger, + [{handler, default, logger_std_h, + #{level => error, + config => #{type => {file, "log/erlang.log"}}}}, + {handler, info, logger_std_h, + #{level => debug, + config => #{type => {file, "log/debug.log"}}}} + ]}]}]. + </code> + </section> + + </section> + + <section> + <marker id="compatibility"/> + <title>Backwards Compatibility with error_logger</title> + <p>Logger provides backwards compatibility with + <c>error_logger</c> in the following ways:</p> + + <taglist> + <tag>API for Logging</tag> + <item> + <p>The <c>error_logger</c> API still exists, but should only + be used by legacy code. It will be removed in a later + release.</p> + <p>Calls + to <seealso marker="error_logger#error_report-1"> + <c>error_logger:error_report/1,2</c></seealso>, + <seealso marker="error_logger#error_msg-1"> + <c>error_logger:error_msg/1,2</c></seealso>, and + corresponding functions for warning and info messages, are + all forwarded to Logger as calls + to <seealso marker="logger#log-3"> + <c>logger:log(Level,Report,Metadata)</c></seealso>.</p> + <p><c>Level = error | warning | info</c> and is taken + from the function name. <c>Report</c> contains the actual + log message, and <c>Metadata</c> contains additional + information which can be used for creating backwards + compatible events for legacy <c>error_logger</c> event + handlers, see + section <seealso marker="#legacy_event_handlers">Legacy + Event Handlers</seealso>.</p> + </item> + <tag>Output Format</tag> + <item> + <p>To get log events on the same format as produced + by <c>error_logger_tty_h</c> and <c>error_logger_file_h</c>, + use the default formatter, <c>logger_formatter</c>, with + configuration parameter <c>legacy_header</c> set + to <c>true</c>. This is the default configuration of + the <c>default</c> handler started by Kernel.</p> + </item> + <tag>Default Format of Log Events from OTP</tag> + <item> + <p>By default, all log events originating from within OTP, + except the former so called "SASL reports", look the same as + before.</p> + </item> + <tag><marker id="sasl_reports"/>SASL Reports</tag> + <item> + <p>By SASL reports we mean supervisor reports, crash reports + and progress reports.</p> + <p>Prior to Erlang/OTP 21.0, these reports were only logged + when the SASL application was running, and they were printed + trough SASL's own event handlers <c>sasl_report_tty_h</c> + and <c>sasl_report_file_h</c>.</p> + <p>The destination of these log events was configured by + <seealso marker="sasl:sasl_app#deprecated_error_logger_config">SASL + configuration parameters</seealso>.</p> + <p>Due to the specific event handlers, the output format + slightly differed from other log events.</p> + <p>As of Erlang/OTP 21.0, the concept of SASL reports is + removed, meaning that the default behaviour is as + follows:</p> + <list> + <item>Supervisor reports, crash reports, and progress reports + are no longer connected to the SASL application.</item> + <item>Supervisor reports and crash reports are issued + as <c>error</c> level log events, and are logged through + the default handler started by Kernel.</item> + <item>Progress reports are issued as <c>info</c> level log + events, and since the default primary log level + is <c>notice</c>, these are not logged by default. To + enable printing of progress reports, set + the <seealso marker="#primary_level">primary log + level</seealso> to <c>info</c>.</item> + <item>The output format is the same for all log + events.</item> + </list> + <p>If the old behaviour is preferred, the Kernel configuration + parameter <seealso marker="kernel_app#logger_sasl_compatible"> + <c>logger_sasl_compatible</c></seealso> can be set + to <c>true</c>. The + <seealso marker="sasl:sasl_app#deprecated_error_logger_config">SASL + configuration parameters</seealso> can then be used as + before, and the SASL reports will only be printed if the + SASL application is running, through a second log handler + named <c>sasl</c>.</p> + <p>All SASL reports have a metadata field <c>domain</c> which + is set to <c>[otp,sasl]</c>. This field can be + used by filters to stop or allow the log events.</p> + <p>See section <seealso marker="sasl:error_logging">SASL User's + Guide</seealso> for more information about the old SASL + error logging functionality.</p> + </item> + <tag><marker id="legacy_event_handlers"/>Legacy Event Handlers</tag> + <item> + <p>To use event handlers written for <c>error_logger</c>, just + add your event handler with</p> + <code> +error_logger:add_report_handler/1,2. + </code> + <p>This automatically starts the error logger event manager, + and adds <c>error_logger</c> as a handler to Logger, with + the following configuration:</p> +<code> +#{level => info, + filter_default => log, + filters => []}. +</code> + <note> + <p>This handler ignores events that do not originate from + the <c>error_logger</c> API, or from within OTP. This + means that if your code uses the Logger API for logging, + then your log events will be discarded by this + handler.</p> + <p>The handler is not overload protected.</p> + </note> + </item> + </taglist> + </section> + + + <section> + <title>Error Handling</title> + <p>Logger does, to a certain extent, check its input data before + forwarding a log event to filters and handlers. It does, + however, not evaluate report callbacks, or check the validity of + format strings and arguments. This means that all filters and + handlers must be careful when formatting the data of a log + event, making sure that it does not crash due to bad input data + or faulty callbacks.</p> + <p>If a filter or handler still crashes, Logger will remove the + filter or handler in question from the configuration, and print + a short error message to the terminal. A debug event containing + the crash reason and other details is also issued.</p> + <p>See section <seealso marker="#log_message">Log + Message</seealso> for more information about report callbacks + and valid forms of log messages.</p> + </section> + + <section> + <title>Example: Add a handler to log info events to file</title> + <p>When starting an Erlang node, the default behaviour is that all + log events on level <c>notice</c> or more severe, are logged to + the terminal via the default handler. To also log info events, + you can either change the primary log level to <c>info</c>:</p> + <pre> +1> <input>logger:set_primary_config(level, info).</input> +ok</pre> + <p>or set the level for one or a few modules only:</p> + <pre> +2> <input>logger:set_module_level(mymodule, info).</input> +ok</pre> + <p>This allows info events to pass through to the default handler, + and be printed to the terminal as well. If there are many info + events, it can be useful to print these to a file instead.</p> + <p>First, set the log level of the default handler + to <c>notice</c>, preventing it from printing info events to the + terminal:</p> + <pre> +3> <input>logger:set_handler_config(default, level, notice).</input> +ok</pre> + <p>Then, add a new handler which prints to file. You can use the + handler + module <seealso marker="logger_std_h"><c>logger_std_h</c></seealso>, + and specify type <c>{file,File}</c>.:</p> + <pre> +4> <input>Config = #{config => #{type => {file,"./info.log"}}, level => info}.</input> +#{config => #{type => {file,"./info.log"}},level => info} +5> <input>logger:add_handler(myhandler, logger_std_h, Config).</input> +ok</pre> + <p>Since <c>filter_default</c> defaults to <c>log</c>, this + handler now receives all log events. If you want info events + only in the file, you must add a filter to stop all non-info + events. The built-in + filter <seealso marker="logger_filters#level-2"> + <c>logger_filters:level/2</c></seealso> + can do this:</p> + <pre> +6> <input>logger:add_handler_filter(myhandler, stop_non_info, + {fun logger_filters:level/2, {stop, neq, info}}).</input> +ok</pre> + <p>See section <seealso marker="#filters">Filters</seealso> for + more information about the filters and the <c>filter_default</c> + configuration parameter.</p> + + </section> + + <section> + <title>Example: Implement a handler</title> + <p>Section <seealso marker="logger#handler_callback_functions">Handler + Callback Functions</seealso> in the logger(3) manual page + describes the callback functions that can be implemented for a + Logger handler.</p> + <p>A handler callback module must export:</p> + <list> + <item><c>log(Log, Config)</c></item> + </list> + <p>It can optionally also export some, or all, of the following:</p> + <list> + <item><c>adding_handler(Config)</c></item> + <item><c>removing_handler(Config)</c></item> + <item><c>changing_config(OldConfig, NewConfig)</c></item> + </list> + <p>When a handler is added, by for example a call + to <seealso marker="logger#add_handler-3"> + <c>logger:add_handler(Id, HModule, Config)</c></seealso>, + Logger first calls <c>HModule:adding_handler(Config)</c>. If + this function returns <c>{ok,Config1}</c>, Logger + writes <c>Config1</c> to the configuration database, and + the <c>logger:add_handler/3</c> call returns. After this, the + handler is installed and must be ready to receive log events as + calls to <c>HModule:log/2</c>.</p> + <p>A handler can be removed by calling + <seealso marker="logger#remove_handler-1"> + <c>logger:remove_handler(Id)</c></seealso>. Logger calls + <c>HModule:removing_handler(Config)</c>, and removes the + handler's configuration from the configuration database.</p> + <p>When <seealso marker="logger#set_handler_config-2"> + <c>logger:set_handler_config/2,3</c></seealso> + or <seealso marker="logger#update_handler_config/2"> + <c>logger:update_handler_config/2</c></seealso> is called, + Logger + calls <c>HModule:changing_config(OldConfig, NewConfig)</c>. If + this function returns <c>{ok,NewConfig1}</c>, Logger + writes <c>NewConfig1</c> to the configuration database.</p> + + <p>A simple handler that prints to the terminal can be implemented + as follows:</p> + <code> +-module(myhandler1). +-export([log/2]). + +log(LogEvent, #{formatter := {FModule, FConfig}}) -> + io:put_chars(FModule:format(LogEvent, FConfig)). + </code> + + <p>Notice that the above handler does not have any overload + protection, and all log events are printed directly from the + client process.</p> + <p>For information and examples of overload protection, please + refer to + section <seealso marker="#overload_protection">Protecting the + Handler from Overload</seealso>, and the implementation + of <seealso marker="logger_std_h"><c>logger_std_h</c></seealso> + and <seealso marker="logger_disk_log_h"><c>logger_disk_log_h</c> + </seealso>.</p> + <p>The following is a simpler example of a handler which logs to a + file through one single process:</p> + <code> +-module(myhandler2). +-export([adding_handler/1, removing_handler/1, log/2]). +-export([init/1, handle_call/3, handle_cast/2, terminate/2]). + +adding_handler(Config) -> + MyConfig = maps:get(config,Config,#{file => "myhandler2.log"}), + {ok, Pid} = gen_server:start(?MODULE, MyConfig, []), + {ok, Config#{config => MyConfig#{pid => Pid}}}. + +removing_handler(#{config := #{pid := Pid}}) -> + gen_server:stop(Pid). + +log(LogEvent,#{config := #{pid := Pid}} = Config) -> + gen_server:cast(Pid, {log, LogEvent, Config}). + +init(#{file := File}) -> + {ok, Fd} = file:open(File, [append, {encoding, utf8}]), + {ok, #{file => File, fd => Fd}}. + +handle_call(_, _, State) -> + {reply, {error, bad_request}, State}. + +handle_cast({log, LogEvent, Config}, #{fd := Fd} = State) -> + do_log(Fd, LogEvent, Config), + {noreply, State}. + +terminate(_Reason, #{fd := Fd}) -> + _ = file:close(Fd), + ok. + +do_log(Fd, LogEvent, #{formatter := {FModule, FConfig}}) -> + String = FModule:format(LogEvent, FConfig), + io:put_chars(Fd, String). + </code> + </section> + + <section> + <marker id="overload_protection"/> + <title>Protecting the Handler from Overload</title> + <p>The default handlers, <seealso marker="logger_std_h"> + <c>logger_std_h</c></seealso> and <seealso marker="logger_disk_log_h"> + <c>logger_disk_log_h</c></seealso>, feature an overload protection + mechanism, which makes it possible for the handlers to survive, + and stay responsive, during periods of high load (when huge + numbers of incoming log requests must be handled). + The mechanism works as follows:</p> + + <section> + <title>Message Queue Length</title> + <p>The handler process keeps track of the length of its message + queue and takes some form of action when the current length exceeds a + configurable threshold. The purpose is to keep the handler in, or to + as quickly as possible get the handler into, a state where it can + keep up with the pace of incoming log events. The memory use of the + handler must never grow larger and larger, since that will eventually + cause the handler to crash. These three thresholds, with associated + actions, exist:</p> + + <taglist> + <tag><c>sync_mode_qlen</c></tag> + <item> + <p>As long as the length of the message queue is lower than this + value, all log events are handled asynchronously. This means that + the client process sending the log event, by calling a log function + in the <seealso marker="logger_chapter#logger_api">Logger API</seealso>, + does not wait for a response from the handler but continues + executing immediately after the event is sent. It is not affected + by the time it takes the handler to print the event to the log + device. If the message queue grows larger than this value, + the handler starts handling log events synchronously instead, + meaning that the client process sending the event must wait for a + response. When the handler reduces the message queue to a + level below the <c>sync_mode_qlen</c> threshold, asynchronous + operation is resumed. The switch from asynchronous to synchronous + mode can slow down the logging tempo of one, or a few, busy senders, + but cannot protect the handler sufficiently in a situation of many + busy concurrent senders.</p> + <p>Defaults to <c>10</c> messages.</p> + </item> + <tag><c>drop_mode_qlen</c></tag> + <item> + <p>When the message queue grows larger than this threshold, the + handler switches to a mode in which it drops all new events that + senders want to log. Dropping an event in this mode means that the + call to the log function never results in a message being sent to + the handler, but the function returns without taking any action. + The handler keeps logging the events that are already in its message + queue, and when the length of the message queue is reduced to a level + below the threshold, synchronous or asynchronous mode is resumed. + Notice that when the handler activates or deactivates drop mode, + information about it is printed in the log.</p> + <p>Defaults to <c>200</c> messages.</p> + </item> + <tag><c>flush_qlen</c></tag> + <item> + <p>If the length of the message queue grows larger than this threshold, + a flush (delete) operation takes place. To flush events, the handler + discards the messages in the message queue by receiving them in a + loop without logging. Client processes waiting for a response from a + synchronous log request receive a reply from the handler indicating + that the request is dropped. The handler process increases its + priority during the flush loop to make sure that no new events + are received during the operation. Notice that after the flush operation + is performed, the handler prints information in the log about how many + events have been deleted.</p> + <p>Defaults to <c>1000</c> messages.</p> + </item> + </taglist> + + <p>For the overload protection algorithm to work properly, it is + required that:</p> + + <p><c>sync_mode_qlen =< drop_mode_qlen =< flush_qlen</c></p> + + <p>and that:</p> + + <p><c>drop_mode_qlen > 1</c></p> + + <p>To disable certain modes, do the following:</p> + <list> + <item>If <c>sync_mode_qlen</c> is set to <c>0</c>, all log events are handled + synchronously. That is, asynchronous logging is disabled.</item> + <item>If <c>sync_mode_qlen</c> is set to the same value as + <c>drop_mode_qlen</c>, synchronous mode is disabled. That is, the handler + always runs in asynchronous mode, unless dropping or flushing is invoked.</item> + <item>If <c>drop_mode_qlen</c> is set to the same value as <c>flush_qlen</c>, + drop mode is disabled and can never occur.</item> + </list> + + <p>During high load scenarios, the length of the handler message queue + rarely grows in a linear and predictable way. Instead, whenever the + handler process is scheduled in, it can have an almost arbitrary number + of messages waiting in the message queue. It is for this reason that the overload + protection mechanism is focused on acting quickly, and quite drastically, + such as immediately dropping or flushing messages, when a large queue length + is detected.</p> + + <p>The values of the previously listed thresholds can be specified by the user. + This way, a handler can be configured to, for example, not drop or flush + messages unless the message queue length of the handler process grows extremely + large. Notice that large amounts of memory can be required for the node under such + circumstances. Another example of user configuration is when, for performance + reasons, the client processes must never be blocked by synchronous log requests. + It is possible, perhaps, that dropping or flushing events is still acceptable, since + it does not affect the performance of the client processes sending the log events.</p> + + <p>A configuration example:</p> + <code type="none"> +logger:add_handler(my_standard_h, logger_std_h, + #{config => #{type => {file,"./system_info.log"}, + sync_mode_qlen => 100, + drop_mode_qlen => 1000, + flush_qlen => 2000}}). + </code> + </section> + + <section> + <title>Controlling Bursts of Log Requests</title> + <p>Large bursts of log events - many events received by the handler + under a short period of time - can potentially cause problems, such as:</p> + <list> + <item>Log files grow very large, very quickly.</item> + <item>Circular logs wrap too quickly so that important data is overwritten.</item> + <item>Write buffers grow large, which slows down file sync operations.</item> + </list> + + <p>For this reason, both built-in handlers offer the possibility to specify the + maximum number of events to be handled within a certain time frame. + With this burst control feature enabled, the handler can avoid choking the log with + massive amounts of printouts. The configuration parameters are:</p> + <taglist> + <tag><c>burst_limit_enable</c></tag> + <item> + <p>Value <c>true</c> enables burst control and <c>false</c> disables it.</p> + <p>Defaults to <c>true</c>.</p> + </item> + <tag><c>burst_limit_max_count</c></tag> + <item> + <p>This is the maximum number of events to handle within a + <c>burst_limit_window_time</c> time frame. After the limit is + reached, successive events are dropped until the end of the time frame.</p> + <p>Defaults to <c>500</c> events.</p> + </item> + <tag><c>burst_limit_window_time</c></tag> + <item> + <p>See the previous description of <c>burst_limit_max_count</c>.</p> + <p>Defaults to <c>1000</c> milliseconds.</p> + </item> + </taglist> + + <p>A configuration example:</p> + <code type="none"> +logger:add_handler(my_disk_log_h, logger_disk_log_h, + #{config => #{file => "./my_disk_log", + burst_limit_enable => true, + burst_limit_max_count => 20, + burst_limit_window_time => 500}}). + </code> + </section> + + <section> + <title>Terminating an Overloaded Handler</title> + <p>It is possible that a handler, even if it can successfully manage peaks + of high load without crashing, can build up a large message queue, or use a + large amount of memory. The overload protection mechanism includes an + automatic termination and restart feature for the purpose of guaranteeing + that a handler does not grow out of bounds. The feature is configured + with the following parameters:</p> + <taglist> + <tag><c>overload_kill_enable</c></tag> + <item> + <p>Value <c>true</c> enables the feature and <c>false</c> disables it.</p> + <p>Defaults to <c>false</c>.</p> + </item> + <tag><c>overload_kill_qlen</c></tag> + <item> + <p>This is the maximum allowed queue length. If the message queue grows + larger than this, the handler process is terminated.</p> + <p>Defaults to <c>20000</c> messages.</p> + </item> + <tag><c>overload_kill_mem_size</c></tag> + <item> + <p>This is the maximum memory size that the handler process is allowed to use. + If the handler grows larger than this, the process is terminated.</p> + <p>Defaults to <c>3000000</c> bytes.</p> + </item> + <tag><c>overload_kill_restart_after</c></tag> + <item> + <p>If the handler is terminated, it restarts automatically after a + delay specified in milliseconds. The value <c>infinity</c> prevents + restarts.</p> + <p>Defaults to <c>5000</c> milliseconds.</p> + </item> + </taglist> + <p>If the handler process is terminated because of overload, it prints + information about it in the log. It also prints information about when a + restart has taken place, and the handler is back in action.</p> + <note> + <p>The sizes of the log events affect the memory needs of the handler. + For information about how to limit the size of log events, see the + <seealso marker="logger_formatter"><c>logger_formatter(3)</c></seealso> + manual page.</p> + </note> + </section> + </section> + + <section> + <title>See Also</title> + <p> + <seealso marker="disk_log"><c>disk_log(3)</c></seealso>, + <seealso marker="error_logger"><c>error_logger(3)</c></seealso>, + <seealso marker="logger"><c>logger(3)</c></seealso>, + <seealso marker="logger_disk_log_h"><c>logger_disk_log_h(3)</c></seealso>, + <seealso marker="logger_filters"><c>logger_filters(3)</c></seealso>, + <seealso marker="logger_formatter"><c>logger_formatter(3)</c></seealso>, + <seealso marker="logger_std_h"><c>logger_std_h(3)</c></seealso>, + <seealso marker="sasl:sasl_app"><c>sasl(6)</c></seealso></p> + </section> +</chapter> diff --git a/lib/kernel/doc/src/logger_disk_log_h.xml b/lib/kernel/doc/src/logger_disk_log_h.xml new file mode 100644 index 0000000000..dfe2ab3275 --- /dev/null +++ b/lib/kernel/doc/src/logger_disk_log_h.xml @@ -0,0 +1,158 @@ +<?xml version="1.0" encoding="utf-8" ?> +<!DOCTYPE erlref SYSTEM "erlref.dtd"> + +<erlref> + <header> + <copyright> + <year>2017</year><year>2018</year> + <holder>Ericsson AB. All Rights Reserved.</holder> + </copyright> + <legalnotice> + Licensed under the Apache License, Version 2.0 (the "License"); + you may not use this file except in compliance with the License. + You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + + Unless required by applicable law or agreed to in writing, software + distributed under the License is distributed on an "AS IS" BASIS, + WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + See the License for the specific language governing permissions and + limitations under the License. + + </legalnotice> + + <title>logger_disk_log_h</title> + <prepared></prepared> + <responsible></responsible> + <docno></docno> + <approved></approved> + <checked></checked> + <date></date> + <rev>A</rev> + <file>logger_disk_log_h.xml</file> + </header> + <module>logger_disk_log_h</module> + <modulesummary>A disk_log based handler for Logger</modulesummary> + + <description> + <p>This is a handler for Logger that offers circular + (wrapped) logs by using <seealso marker="disk_log"><c>disk_log</c></seealso>. + Multiple instances of this handler can be added to Logger, and each instance + prints to its own disk log file, created with the name and settings specified + in the handler configuration.</p> + <p>The default standard handler, + <seealso marker="logger_std_h"><c>logger_std_h</c></seealso>, can be + replaced by a disk_log handler at startup of the Kernel application. + See an example of this below.</p> + <p>The handler has an overload protection mechanism that keeps the handler + process and the Kernel application alive during high loads of log + events. How overload protection works, and how to configure it, is + described in the + <seealso marker="logger_chapter#overload_protection"><c>User's Guide</c> + </seealso>.</p> + <p>To add a new instance of the disk_log handler, use + <seealso marker="logger#add_handler-3"><c>logger:add_handler/3</c> + </seealso>. The handler configuration argument is a map which can contain + general configuration parameters, as documented in the + <seealso marker="logger_chapter#handler_configuration"><c>User's Guide</c> + </seealso>, and handler specific parameters. The specific data + is stored in a sub map with the key <c>config</c>, and can contain the + following parameters:</p> + <taglist> + <tag><c>file</c></tag> + <item> + <p>This is the full name of the disk log file. The option + corresponds to the <c>name</c> property in the + <seealso marker="disk_log#open-1"><c>dlog_option()</c></seealso> + datatype.</p> + </item> + <tag><c>type</c></tag> + <item> + <p>This is the disk log type, <c>wrap</c> or <c>halt</c>. The option + corresponds to the <c>type</c> property in the + <seealso marker="disk_log#open-1"><c>dlog_option()</c></seealso> + datatype.</p> + <p>Defaults to <c>wrap</c>.</p> + </item> + <tag><c>max_no_files</c></tag> + <item> + <p>This is the maximum number of files that disk_log uses + for its circular logging. The option + corresponds to the <c>MaxNoFiles</c> element in the <c>size</c> property in the + <seealso marker="disk_log#open-1"><c>dlog_option()</c></seealso> + datatype.</p> + <p>Defaults to <c>10</c>.</p> + <p>The setting has no effect on a halt log.</p> + </item> + <tag><c>max_no_bytes</c></tag> + <item> + <p>This is the maximum number of bytes that is written to + a log file before disk_log proceeds with the next file in order, or + generates an error in case of a full halt log. The option + corresponds to the <c>MaxNoBytes</c> element in the <c>size</c> property in the + <seealso marker="disk_log#open-1"><c>dlog_option()</c></seealso> + datatype.</p> + <p>Defaults to <c>1048576</c> bytes for a wrap log, and + <c>infinity</c> for a halt log.</p> + </item> + <tag><c>filesync_repeat_interval</c></tag> + <item> + <p>This value, in milliseconds, specifies how often the handler does + a disk_log sync operation to write buffered data to disk. The handler attempts + the operation repeatedly, but only performs a new sync if something has + actually been logged.</p> + <p>Defaults to <c>5000</c> milliseconds.</p> + <p>If <c>no_repeat</c> is set as value, the repeated sync operation + is disabled. The user can also call the + <seealso marker="logger_disk_log_h#filesync-1"><c>filesync/1</c> + </seealso> function to perform a disk_log sync.</p> + </item> + </taglist> + <p>Other configuration parameters exist, to be used for customizing + the overload protection behaviour. The same parameters are used both in the + standard handler and the disk_log handler, and are documented in the + <seealso marker="logger_chapter#overload_protection"><c>User's Guide</c> + </seealso>.</p> + <p>Notice that when changing the configuration of the handler in runtime, the + disk_log options (<c>file</c>, <c>type</c>, <c>max_no_files</c>, + <c>max_no_bytes</c>) must not be modified.</p> + <p>Example of adding a disk_log handler:</p> + <code type="none"> +logger:add_handler(my_disk_log_h, logger_disk_log_h, + #{config => #{file => "./my_disk_log", + type => wrap, + max_no_files => 4, + max_no_bytes => 10000}, + filesync_repeat_interval => 1000}}). + </code> + <p>To use the disk_log handler instead of the default standard + handler when starting an Erlang node, change the Kernel default logger to + use <c>logger_disk_log_h</c>. Example:</p> + <code type="none"> +erl -kernel logger '[{handler,default,logger_disk_log_h, + #{config => #{file => "./system_disk_log"}}}]' + </code> + </description> + + <funcs> + + <func> + <name name="filesync" arity="1" clause_i="1"/> + <fsummary>Writes buffered data to disk.</fsummary> + <desc> + <p>Write buffered data to disk.</p> + </desc> + </func> + + </funcs> + + <section> + <title>See Also</title> + <p><seealso marker="logger"><c>logger(3)</c></seealso>, + <seealso marker="logger_std_h"><c>logger_std_h(3)</c></seealso>, + <seealso marker="disk_log"><c>disk_log(3)</c></seealso></p> + </section> +</erlref> + + diff --git a/lib/kernel/doc/src/logger_filters.xml b/lib/kernel/doc/src/logger_filters.xml new file mode 100644 index 0000000000..90f1fcc270 --- /dev/null +++ b/lib/kernel/doc/src/logger_filters.xml @@ -0,0 +1,254 @@ +<?xml version="1.0" encoding="utf-8" ?> +<!DOCTYPE erlref SYSTEM "erlref.dtd"> + +<erlref> + <header> + <copyright> + <year>2018</year> + <holder>Ericsson AB. All Rights Reserved.</holder> + </copyright> + <legalnotice> + Licensed under the Apache License, Version 2.0 (the "License"); + you may not use this file except in compliance with the License. + You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + + Unless required by applicable law or agreed to in writing, software + distributed under the License is distributed on an "AS IS" BASIS, + WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + See the License for the specific language governing permissions and + limitations under the License. + + </legalnotice> + + <title>logger_filters</title> + <prepared></prepared> + <responsible></responsible> + <docno></docno> + <approved></approved> + <checked></checked> + <date></date> + <rev>A</rev> + <file>logger_filters.xml</file> + </header> + <module>logger_filters</module> + <modulesummary>Filters to use with Logger.</modulesummary> + + <description> + <p>All functions exported from this module can be used as primary + or handler + filters. See <seealso marker="logger#add_primary_filter-2"> + <c>logger:add_primary_filter/2</c></seealso> + and <seealso marker="logger#add_handler_filter-3"> + <c>logger:add_handler_filter/3</c></seealso> for more information + about how filters are added.</p> + <p>Filters are removed with <seealso marker="logger#remove_primary_filter-1"> + <c>logger:remove_primary_filter/1</c></seealso> + and <seealso marker="logger#remove_handler_filter-2"> + <c>logger:remove_handler_filter/2</c></seealso>.</p> + </description> + + <funcs> + <func> + <name name="domain" arity="2"/> + <fsummary>Filter log events based on the domain field in + metadata.</fsummary> + <desc> + <p>This filter provides a way of filtering log events based on a + <c>domain</c> field in <c>Metadata</c>. This field is + optional, and the purpose of using it is to group log events + from, for example, a specific functional area. This allows + filtering or other specialized treatment in a Logger + handler.</p> + + <p>A domain field must be a list of atoms, creating smaller + and more specialized domains as the list grows longer. The + greatest domain is <c>[]</c>, which comprises all possible + domains.</p> + + <p>For example, consider the following domains:</p> + <pre> +D1 = [otp] +D2 = [otp, sasl]</pre> + + <p><c>D1</c> is the greatest of the two, and is said to be a + super-domain of <c>D2</c>. <c>D2</c> is a + sub-domain <c>D1</c>. Both <c>D1</c> and <c>D2</c> are + sub-domains of <c>[]</c>.</p> + + <p>The above domains are used for logs originating from + Erlang/OTP. D1 specifies that the log event comes from + Erlang/OTP in general, and D2 indicates that the log event + is a so + called <seealso marker="logger_chapter#sasl_reports">SASL + report</seealso>.</p> + + <p>The <c><anno>Extra</anno></c> parameter to + the <c>domain/2</c> function is specified when adding the + filter via <seealso marker="logger#add_primary_filter-2"> + <c>logger:add_primary_filter/2</c></seealso> + or <seealso marker="logger#add_handler_filter-3"> + <c>logger:add_handler_filter/3</c></seealso>.</p> + + <p>The filter compares the value of the <c>domain</c> field in + the log event's metadata (<c>Domain</c>) against + <c><anno>MatchDomain</anno></c>. The filter matches if the + value of <c>Compare</c> is:</p> + + <taglist> + <tag><c>sub</c></tag> + <item> + <p>and <c>Domain</c> is equal to or a sub-domain + of <c>MatchDomain</c>, that is, if <c>MatchDomain</c> is + a prefix of <c>Domain</c>.</p> + </item> + <tag><c>super</c></tag> + <item> + <p>and <c>Domain</c> is equal to or a super-domain + of <c>MatchDomain</c>, that is, if <c>Domain</c> is a + prefix of <c>MatchDomain</c>.</p> + </item> + <tag><c>equal</c></tag> + <item> + <p>and <c>Domain</c> is equal to <c>MatchDomain</c>.</p> + </item> + <tag><c>not_equal</c></tag> + <item> + <p>and <c>Domain</c> differs from <c>MatchDomain</c>, or + if there is no domain field in metadata.</p> + </item> + <tag><c>undefined</c></tag> + <item> + <p>and there is no domain field in metadata. In this + case <c><anno>MatchDomain</anno></c> must be set + to <c>[]</c>.</p> + </item> + </taglist> + + <p>If the filter matches and <c><anno>Action</anno></c> is + <c>log</c>, the log event is allowed. If the filter matches + and <c><anno>Action</anno></c> is <c>stop</c>, the log event + is stopped.</p> + + <p>If the filter does not match, it returns <c>ignore</c>, + meaning that other filters, or the value of the + configuration parameter <c>filter_default</c>, decide if the + event is allowed or not.</p> + + <p>Log events that do not contain any domain field, match only + when <c><anno>Compare</anno></c> is equal + to <c>undefined</c> or <c>not_equal</c>.</p> + + <p>Example: stop all events with domain <c>[otp, + sasl | _]</c></p> + + <code> +logger:set_handler_config(h1, filter_default, log). % this is the default +Filter = {fun logger_filters:domain/2, {stop, sub, [otp, sasl]}}. +logger:add_handler_filter(h1, no_sasl, Filter). +ok</code> + </desc> + </func> + + <func> + <name name="level" arity="2"/> + <fsummary>Filter log events based on the log level.</fsummary> + <desc> + <p>This filter provides a way of filtering log events based + on the log level. It matches log events by comparing the + log level with a specified <c>MatchLevel</c></p> + + <p>The <c><anno>Extra</anno></c> parameter is specified when + adding the filter + via <seealso marker="logger#add_primary_filter-2"> + <c>logger:add_primary_filter/2</c></seealso> + or <seealso marker="logger#add_handler_filter-3"> + <c>logger:add_handler_filter/3</c></seealso>.</p> + + <p>The filter compares the value of the event's log level + (<c>Level</c>) to <c><anno>MatchLevel</anno></c> by + calling <seealso marker="logger#compare_levels-2"> + <c>logger:compare_levels(Level, MatchLevel)</c></seealso>. + The filter matches if the value + of <c><anno>Operator</anno></c> is:</p> + + <taglist> + <tag><c>neq</c></tag> + <item><p>and the compare function returns <c>lt</c> + or <c>gt</c>.</p></item> + <tag><c>eq</c></tag> + <item><p>and the compare function returns <c>eq</c>.</p></item> + <tag><c>lt</c></tag> + <item><p>and the compare function returns <c>lt</c>.</p></item> + <tag><c>gt</c></tag> + <item><p>and the compare function returns <c>gt</c>.</p></item> + <tag><c>lteq</c></tag> + <item><p>and the compare function returns <c>lt</c> + or <c>eq</c>.</p></item> + <tag><c>gteq</c></tag> + <item><p>and the compare function returns <c>gt</c> + or <c>eq</c>.</p></item> + </taglist> + + <p>If the filter matches and <c><anno>Action</anno></c> is + <c>log</c>, the log event is allowed. If the filter + matches and <c><anno>Action</anno></c> is <c>stop</c>, the + log event is stopped.</p> + + <p>If the filter does not match, it returns <c>ignore</c>, + meaning that other filters, or the value of the + configuration parameter <c>filter_default</c>, will decide + if the event is allowed or not.</p> + + <p>Example: only allow debug level log events</p> + + <code> +logger:set_handler_config(h1, filter_default, stop). +Filter = {fun logger_filters:level/2, {log, eq, debug}}. +logger:add_handler_filter(h1, debug_only, Filter). +ok</code> + </desc> + </func> + + <func> + <name name="progress" arity="2"/> + <fsummary>Filter progress reports from supervisor and application_controller.</fsummary> + <desc> + <p>This filter matches all progress reports + from <c>supervisor</c> and <c>application_controller</c>.</p> + + <p>If <c><anno>Extra</anno></c> is <c>log</c>, the progress + reports are allowed. If <c><anno>Extra</anno></c> + is <c>stop</c>, the progress reports are stopped.</p> + + <p>The filter returns <c>ignore</c> for all other log events.</p> + </desc> + </func> + + <func> + <name name="remote_gl" arity="2"/> + <fsummary>Filter events with group leader on remote node.</fsummary> + <desc> + <p>This filter matches all events originating from a process + that has its group leader on a remote node.</p> + + <p>If <c><anno>Extra</anno></c> is <c>log</c>, the matching + events are allowed. If <c><anno>Extra</anno></c> + is <c>stop</c>, the matching events are stopped.</p> + + <p>The filter returns <c>ignore</c> for all other log events.</p> + </desc> + </func> + + </funcs> + + <section> + <title>See Also</title> + <p> + <seealso marker="logger"><c>logger(3)</c></seealso> + </p> + </section> +</erlref> + + diff --git a/lib/kernel/doc/src/logger_formatter.xml b/lib/kernel/doc/src/logger_formatter.xml new file mode 100644 index 0000000000..9226d19834 --- /dev/null +++ b/lib/kernel/doc/src/logger_formatter.xml @@ -0,0 +1,355 @@ +<?xml version="1.0" encoding="utf-8" ?> +<!DOCTYPE erlref SYSTEM "erlref.dtd"> + +<erlref> + <header> + <copyright> + <year>2017</year><year>2018</year> + <holder>Ericsson AB. All Rights Reserved.</holder> + </copyright> + <legalnotice> + Licensed under the Apache License, Version 2.0 (the "License"); + you may not use this file except in compliance with the License. + You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + + Unless required by applicable law or agreed to in writing, software + distributed under the License is distributed on an "AS IS" BASIS, + WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + See the License for the specific language governing permissions and + limitations under the License. + + </legalnotice> + + <title>logger_formatter</title> + <prepared></prepared> + <responsible></responsible> + <docno></docno> + <approved></approved> + <checked></checked> + <date></date> + <rev>A</rev> + <file>logger_formatter.xml</file> + </header> + <module>logger_formatter</module> + <modulesummary>Default formatter for Logger.</modulesummary> + + <description> + <p>Each Logger handler has a configured formatter specified as a + module and a configuration term. The purpose of the formatter is + to translate the log events to a final printable string + (<seealso marker="stdlib:unicode#type-chardata"><c>unicode:chardata()</c> + </seealso>) which can be written to the output device of the + handler. See + sections <seealso marker="logger_chapter#handlers">Handlers</seealso> + and <seealso marker="logger_chapter#formatters">Formatters</seealso> + in the Kernel User's Guide for more information.</p> + <p><c>logger_formatter</c> is the default formatter used by + Logger.</p> + </description> + + + <datatypes> + <datatype> + <name name="config"/> + <desc> + <p>The configuration term for <c>logger_formatter</c> is a + <seealso marker="stdlib:maps">map</seealso>, and the + following keys can be set as configuration parameters:</p> + <taglist> + <tag><marker id="chars_limit"/> + <c>chars_limit = integer() > 0 | unlimited</c></tag> + <item> + <p>A positive integer representing the value of the option + with the same name to be used when calling + <seealso marker="stdlib:io_lib#format-3"> + <c>io_lib:format/3</c></seealso>. + This value limits the total number of characters printed + for each log event. Notice that this is a soft limit. For a + hard truncation limit, see option <c>max_size</c>.</p> + <p>Defaults to <c>unlimited</c>.</p> + </item> + <tag><marker id="depth"/><c>depth = integer() > 0 | unlimited</c></tag> + <item> + <p>A positive integer representing the maximum depth to + which terms shall be printed by this formatter. Format + strings passed to this formatter are rewritten. The + format controls ~p and ~w are replaced with ~P and ~W, + respectively, and the value is used as the depth + parameter. For details, see + <seealso marker="stdlib:io#format-2"><c>io:format/2,3</c></seealso> + in STDLIB.</p> + <p>Defaults to <c>unlimited</c>.</p> + </item> + <tag><c>encoding = </c><seealso marker="stdlib:unicode#type-encoding"> + <c>unicode:encoding()</c></seealso></tag> + <item> + <p>This parameter must reflect the encoding of the device + that the handler prints to.</p> + <p>Defaults to <c>utf8</c></p> + </item> + <tag><c>legacy_header = boolean()</c></tag> + <item> + <p>If set to <c>true</c> a header field is added to + logger_formatter's part of <c>Metadata</c>. The value of + this field is a string similar to the header created by + the + old <seealso marker="error_logger"><c>error_logger</c></seealso> + event handlers. It can be included in the log event by + adding the list <c>[logger_formatter,header]</c> to the + template. See the description of + the <seealso marker="#type-template"><c>template()</c></seealso> + type for more information.</p> + <p>Defaults to <c>false</c>.</p> + </item> + <tag><marker id="max_size"/> + <c>max_size = integer() > 0 | unlimited</c></tag> + <item> + <p>A positive integer representing the absolute maximum size a + string returned from this formatter can have. If the + formatted string is longer, after possibly being limited + by <c>chars_limit</c> or <c>depth</c>, it is truncated.</p> + <p>Defaults to <c>unlimited</c>.</p> + </item> + <tag><c>report_cb = </c><seealso marker="logger#type-report_cb"> + <c>logger:report_cb()</c></seealso></tag> + <item> + <p>A report callback is used by the formatter to transform + log messages on report form to a format string and + arguments. The report callback can be specified in the + metadata for the log event. If no report callback exists + in metadata, <c>logger_formatter</c> will + use <seealso marker="logger#format_report-1"> + <c>logger:format_report/1</c></seealso> as default + callback.</p> + <p>If this configuration parameter is set, it replaces + both the default report callback, and any report + callback found in metadata. That is, all reports are + converted by this configured function.</p> + </item> + <tag><c>single_line = boolean()</c></tag> + <item> + <p>If set to <c>true</c>, all newlines in the message are + replaced with <c>", "</c>, and white spaces following + directly after newlines are removed. Notice that newlines + added by the <c>template</c> parameter are not replaced.</p> + <p>Defaults to <c>true</c>.</p> + </item> + <tag><marker id="template"/> + <c>template = </c><seealso marker="#type-template"><c>template()</c> + </seealso></tag> + <item> + <p>The template describes how the formatted string is + composed by combining different data values from the log + event. See the description of + the <seealso marker="#type-template"><c>template()</c></seealso> + type for more information about this.</p> + </item> + <tag><c>time_designator = byte()</c></tag> + <item> + <p>Timestamps are formatted according to RFC3339, and the + time designator is the character used as date and time + separator.</p> + <p>Defaults to <c>$T</c>.</p> + <p>The value of this parameter is used as + the <c>time_designator</c> option + to <seealso marker="stdlib:calendar#system_time_to_rfc3339-2"> + <c>calendar:system_time_to_rcf3339/2</c></seealso>.</p> + </item> + <tag><c>time_offset = integer() | [byte()]</c></tag> + <item> + <p>The time offset, either a string or an integer, to be + used when formatting the timestamp.</p> + <p>An empty string is interpreted as local time. The + values <c>"Z"</c>, <c>"z"</c> or <c>0</c> are + interpreted as Universal Coordinated Time (UTC).</p> + <p>Strings, other than <c>"Z"</c>, <c>"z"</c>, + or <c>""</c>, must be on the form <c>±[hh]:[mm]</c>, for + example <c>"-02:00"</c> or <c>"+00:00"</c>.</p> + <p>Integers must be in microseconds, meaning that the + offset <c>7200000000</c> is equivalent + to <c>"+02:00"</c>.</p> + <p>Defaults to an empty string, meaning that timestamps + are displayed in local time. However, for backwards + compatibility, if the SASL configuration + parameter <seealso marker="sasl:sasl_app#utc_log"> + <c>utc_log</c></seealso><c>=true</c>, the default is + changed to <c>"Z"</c>, meaning that timestamps are displayed + in UTC.</p> + <p>The value of this parameter is used as + the <c>offset</c> option + to <seealso marker="stdlib:calendar#system_time_to_rfc3339-2"> + <c>calendar:system_time_to_rcf3339/2</c></seealso>.</p> + </item> + </taglist> + </desc> + </datatype> + <datatype> + <name name="metakey"/> + <desc> + <p></p> + </desc> + </datatype> + <datatype> + <name name="template"/> + <desc> + <p>The template is a list of atoms, atom lists, tuples and strings. The + atoms <c>level</c> or <c>msg</c>, are treated as + placeholders for the severity level and the log message, + respectively. Other atoms or atom lists are interpreted as + placeholders for metadata, where atoms are expected to match + top level keys, and atom lists represent paths to sub keys when + the metadata is a nested map. For example the + list <c>[key1,key2]</c> is replaced by the value of + the <c>key2</c> field in the nested map below. The + atom <c>key1</c> on its own is replaced by the complete + value of the <c>key1</c> field. The values are converted to + strings.</p> + + <code> +#{key1 => #{key2 => my_value, + ...} + ...}</code> + + <p>Tuples in the template express if-exist tests for metadata + keys. For example, the following tuple says that + if <c>key1</c> exists in the metadata map, + print <c>"key1=Value"</c>, where <c>Value</c> is the value + that <c>key1</c> is associated with in the metadata map. If + <c>key1</c> does not exist, print nothing.</p> + <code> +{key1, ["key1=",key1], []}</code> + + <p>Strings in the template are printed literally.</p> + <p>The default value for the <c>template</c> configuration + parameter depends on the value of the <c>single_line</c> + and <c>legacy_header</c> configuration parameters as + follows.</p> + + <p>The log event used in the examples is:</p> + <code> +?LOG_ERROR("name: ~p~nexit_reason: ~p", [my_name, "It crashed"])</code> + + <taglist> + <tag><c>legacy_header = true, single_line = false</c></tag> + <item> + <p>Default + template: <c>[[logger_formatter,header],"\n",msg,"\n"]</c></p> + + <p>Example log entry:</p> + <code type="none"> +=ERROR REPORT==== 17-May-2018::18:30:19.453447 === +name: my_name +exit_reason: "It crashed"</code> + + <p>Notice that all eight levels can occur in the heading, + not only <c>ERROR</c>, <c>WARNING</c> or <c>INFO</c> as + <seealso marker="error_logger"><c>error_logger</c></seealso> + produces. And microseconds are added at the end of the + timestamp.</p> + </item> + + <tag><c>legacy_header = true, single_line = true</c></tag> + <item> + <p>Default + template: <c>[[logger_formatter,header],"\n",msg,"\n"]</c></p> + + <p>Notice that the template is here the same as + for <c>single_line=false</c>, but the resulting log entry + differs in that there is only one line after the + heading:</p> + <code type="none"> +=ERROR REPORT==== 17-May-2018::18:31:06.952665 === +name: my_name, exit_reason: "It crashed"</code> + </item> + + <tag><c>legacy_header = false, single_line = true</c></tag> + <item> + <p>Default template: <c>[time," ",level,": ",msg,"\n"]</c></p> + + <p>Example log entry:</p> + <code type="none"> +2018-05-17T18:31:31.152864+02:00 error: name: my_name, exit_reason: "It crashed"</code> + </item> + + <tag><c>legacy_header = false, single_line = false</c></tag> + <item> + <p>Default template: <c>[time," ",level,":\n",msg,"\n"]</c></p> + + <p>Example log entry:</p> + <code type="none"> +2018-05-17T18:32:20.105422+02:00 error: +name: my_name +exit_reason: "It crashed"</code> + </item> + </taglist> + </desc> + </datatype> + </datatypes> + + <funcs> + <func> + <name name="check_config" arity="1"/> + <fsummary>Validates the given formatter configuration.</fsummary> + <desc> + <p>The function is called by Logger when the formatter + configuration for a handler is set or modified. It + returns <c>ok</c> if the configuration is valid, + and <c>{error,term()}</c> if it is faulty.</p> + <p>The following Logger API functions can trigger this callback:</p> + <list> + <item><seealso marker="logger#add_handler-3"> + <c>logger:add_handler/3</c></seealso></item> + <item><seealso marker="logger#set_handler_config-2"> + <c>logger:set_handler_config/2,3</c></seealso></item> + <item><seealso marker="logger#update_handler_config-2"> + <c>logger:updata_handler_config/2</c></seealso></item> + <item><seealso marker="logger#update_formatter_config-2"> + <c>logger:update_formatter_config/2</c></seealso></item> + </list> + </desc> + </func> + <func> + <name name="format" arity="2"/> + <fsummary>Formats the given message.</fsummary> + <desc> + <p>This the formatter callback function to be called from + handlers. The log event is processed as follows:</p> + <list> + <item>If the message is on report form, it is converted to + <c>{Format,Args}</c> by calling the report callback. See + section <seealso marker="logger_chapter#log_message">Log + Message</seealso> in the Kernel User's Guide for more + information about report callbacks and valid forms of log + messages.</item> + <item>The message size is limited according to the values of + configuration parameters <seealso marker="#chars_limit"> + <c>chars_limit</c></seealso> + and <seealso marker="#depth"><c>depth</c></seealso>.</item> + <item>The full log entry is composed according to + the <seealso marker="#template"><c>template</c></seealso>.</item> + <item>If the final string is too long, it is truncated + according to the value of configuration + parameter <seealso marker="#max_size"><c>max_size</c></seealso>.</item> + </list> + </desc> + </func> + </funcs> + + <section> + <title>See Also</title> + <p> + <seealso marker="stdlib:calendar"><c>calendar(3)</c></seealso>, + <seealso marker="error_logger"><c>error_logger(3)</c></seealso>, + <seealso marker="stdlib:io"><c>io(3)</c></seealso>, + <seealso marker="stdlib:io_lib"><c>io_lib(3)</c></seealso>, + <seealso marker="logger"><c>logger(3)</c></seealso>, + <seealso marker="stdlib:maps"><c>maps(3)</c></seealso>, + <seealso marker="sasl:sasl_app"><c>sasl(6)</c></seealso>, + <seealso marker="stdlib:unicode"><c>unicode(3)</c></seealso> + </p> + </section> +</erlref> + + diff --git a/lib/kernel/doc/src/logger_std_h.xml b/lib/kernel/doc/src/logger_std_h.xml new file mode 100644 index 0000000000..b526ed037d --- /dev/null +++ b/lib/kernel/doc/src/logger_std_h.xml @@ -0,0 +1,130 @@ +<?xml version="1.0" encoding="utf-8" ?> +<!DOCTYPE erlref SYSTEM "erlref.dtd"> + +<erlref> + <header> + <copyright> + <year>2017</year><year>2018</year> + <holder>Ericsson AB. All Rights Reserved.</holder> + </copyright> + <legalnotice> + Licensed under the Apache License, Version 2.0 (the "License"); + you may not use this file except in compliance with the License. + You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + + Unless required by applicable law or agreed to in writing, software + distributed under the License is distributed on an "AS IS" BASIS, + WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + See the License for the specific language governing permissions and + limitations under the License. + + </legalnotice> + + <title>logger_std_h</title> + <prepared></prepared> + <responsible></responsible> + <docno></docno> + <approved></approved> + <checked></checked> + <date></date> + <rev>A</rev> + <file>logger_std_h.xml</file> + </header> + <module>logger_std_h</module> + <modulesummary>Standard handler for Logger.</modulesummary> + + <description> + <p>This is the standard handler for Logger. + Multiple instances of this handler can be added to + Logger, and each instance prints logs to <c>standard_io</c>, + <c>standard_error</c>, or to file.</p> + <p>The handler has an overload protection mechanism that keeps the handler + process and the Kernel application alive during high loads of log + events. How overload protection works, and how to configure it, is + described in the + <seealso marker="logger_chapter#overload_protection"><c>User's Guide</c> + </seealso>.</p> + <p>To add a new instance of the standard handler, use + <seealso marker="logger#add_handler-3"><c>logger:add_handler/3</c> + </seealso>. The handler configuration argument is a map which can contain + general configuration parameters, as documented in the + <seealso marker="logger_chapter#handler_configuration"><c>User's Guide</c> + </seealso>, and handler specific parameters. The specific data + is stored in a sub map with the key <c>config</c>, and can contain the + following parameters:</p> + <taglist> + <tag><marker id="type"/><c>type</c></tag> + <item> + <p>This has the value <c>standard_io</c>, <c>standard_error</c>, + <c>{file,LogFileName}</c>, or <c>{file,LogFileName,LogFileOpts}</c>.</p> + <p> Defaults to <c>standard_io</c>.</p> + <p>It is recommended not to specify <c>LogFileOpts</c> unless absolutely + necessary. The default options used by the handler to open a file for logging are + <c>raw</c>, <c>append</c>, and <c>delayed_write</c>. Notice that the standard + handler does not have support for circular logging. Use the disk_log handler, + <seealso marker="logger_disk_log_h"><c>logger_disk_log_h</c></seealso>, + for this.</p> + </item> + <tag><c>filesync_repeat_interval</c></tag> + <item> + <p>This value, in milliseconds, specifies how often the handler does + a file sync operation to write buffered data to disk. The handler attempts + the operation repeatedly, but only performs a new sync if something has + actually been logged.</p> + <p>Defaults to <c>5000</c> milliseconds.</p> + <p>If <c>no_repeat</c> is set as value, the repeated file sync operation + is disabled, and it is the operating system settings that determine + how quickly or slowly data is written to disk. The user can also call + the <seealso marker="logger_std_h#filesync-1"><c>filesync/1</c></seealso> + function to perform a file sync.</p> + </item> + </taglist> + <p>Other configuration parameters exist, to be used for customizing + the overload protection behaviour. The same parameters are used both in the + standard handler and the disk_log handler, and are documented in the + <seealso marker="logger_chapter#overload_protection"><c>User's Guide</c> + </seealso>.</p> + <p>Notice that if changing the configuration of the handler in runtime, + the <c>type</c> parameter must not be modified.</p> + <p>Example of adding a standard handler:</p> + <code type="none"> +logger:add_handler(my_standard_h, logger_std_h, + #{config => #{type => {file,"./system_info.log"}, + filesync_repeat_interval => 1000}}). + </code> + <p>To set the default handler, that starts initially with + the Kernel application, to log to file instead of <c>standard_io</c>, + change the Kernel default logger configuration. Example:</p> + <code type="none"> +erl -kernel logger '[{handler,default,logger_std_h, + #{config => #{type => {file,"./log.log"}}}}]' + </code> + <p>An example of how to replace the standard handler with a disk_log handler + at startup is found in the + <seealso marker="logger_disk_log_h"><c>logger_disk_log_h</c></seealso> + manual.</p> + </description> + + <funcs> + + <func> + <name name="filesync" arity="1" clause_i="1"/> + <fsummary>Writes buffered data to disk.</fsummary> + <desc> + <p>Write buffered data to disk.</p> + </desc> + </func> + + </funcs> + + <section> + <title>See Also</title> + <p><seealso marker="logger"><c>logger(3)</c></seealso>, + <seealso marker="logger_disk_log_h"> + <c>logger_disk_log_h(3)</c></seealso></p> + </section> +</erlref> + + diff --git a/lib/kernel/doc/src/net_kernel.xml b/lib/kernel/doc/src/net_kernel.xml index 0b94fc0fa6..d3bd7365e2 100644 --- a/lib/kernel/doc/src/net_kernel.xml +++ b/lib/kernel/doc/src/net_kernel.xml @@ -56,7 +56,7 @@ $ <input>erl -sname foobar</input></pre> <p>Normally, connections are established automatically when another node is referenced. This functionality can be disabled by setting Kernel configuration parameter - <c>dist_auto_connect</c> to <c>false</c>, see + <c>dist_auto_connect</c> to <c>never</c>, see <seealso marker="kernel_app"><c>kernel(6)</c></seealso>. In this case, connections must be established explicitly by calling <seealso marker="#connect_node/1"><c>connect_node/1</c></seealso>.</p> @@ -102,8 +102,10 @@ $ <input>erl -sname foobar</input></pre> <fsummary>Establish a connection to a node.</fsummary> <desc> <p>Establishes a connection to <c><anno>Node</anno></c>. Returns - <c>true</c> if successful, <c>false</c> if not, and <c>ignored</c> - if the local node is not alive.</p> + <c>true</c> if a connection was established or was already + established or if <c><anno>Node</anno></c> is the local node + itself. Returns <c>false</c> if the connection attempt failed, and + <c>ignored</c> if the local node is not alive.</p> </desc> </func> @@ -230,7 +232,12 @@ $ <input>erl -sname foobar</input></pre> <item> <p>The tuple <c>{nodedown_reason, Reason}</c> is included in <c>InfoList</c> in <c>nodedown</c> messages.</p> - <p><c>Reason</c> can be any of the following:</p> + <p> + <c>Reason</c> can, depending on which + distribution module or process that is used be any term, + but for the standard TCP distribution module it is + any of the following: + </p> <taglist> <tag><c>connection_setup_failed</c></tag> <item><p>The connection setup failed (after <c>nodeup</c> diff --git a/lib/kernel/doc/src/notes.xml b/lib/kernel/doc/src/notes.xml index 1b7f11d4fa..5884f93878 100644 --- a/lib/kernel/doc/src/notes.xml +++ b/lib/kernel/doc/src/notes.xml @@ -4,7 +4,7 @@ <chapter> <header> <copyright> - <year>2004</year><year>2017</year> + <year>2004</year><year>2018</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> @@ -31,6 +31,289 @@ </header> <p>This document describes the changes made to the Kernel application.</p> +<section><title>Kernel 6.0</title> + + <section><title>Fixed Bugs and Malfunctions</title> + <list> + <item> + <p> Clarify the documentation of <c>rpc:multicall/5</c>. + </p> + <p> + Own Id: OTP-10551</p> + </item> + <item> + <p> + The DNS resolver when getting econnrefused from a server + retained an invalid socket so look up towards the next + server(s) also failed.</p> + <p> + Own Id: OTP-13133 Aux Id: PR-1557 </p> + </item> + <item> + <p> + No resolver backend returns V4Mapped IPv6 addresses any + more. This was inconsistent before, some did, some did + not. To facilitate working with such addresses a new + function <c>inet:ipv4_mapped_ipv6_address/1</c> has been + added.</p> + <p> + *** POTENTIAL INCOMPATIBILITY ***</p> + <p> + Own Id: OTP-13761 Aux Id: ERL-503 </p> + </item> + <item> + <p> + The type specifications for <c>file:posix/0</c> and + <c>inet:posix/0</c> have been updated according to which + errors file and socket operations should be able to + return.</p> + <p> + Own Id: OTP-14019 Aux Id: ERL-550 </p> + </item> + <item> + <p> + Fix name resolving in IPv6 only environments when doing + the initial distributed connection.</p> + <p> + Own Id: OTP-14501</p> + </item> + <item> + <p> File operations used to accept <seealso + marker="kernel:file#type-name_all">filenames</seealso> + containing null characters (integer value zero). This + caused the name to be truncated and in some cases + arguments to primitive operations to be mixed up. + Filenames containing null characters inside the filename + are now <em>rejected</em> and will cause primitive file + operations to fail. </p> <p> Also environment variable + operations used to accept <seealso + marker="kernel:os#type-env_var_name">names</seealso> and + <seealso + marker="kernel:os#type-env_var_value">values</seealso> of + environment variables containing null characters (integer + value zero). This caused operations to silently produce + erroneous results. Environment variable names and values + containing null characters inside the name or value are + now <em>rejected</em> and will cause environment variable + operations to fail. </p> <p>Primitive environment + variable operations also used to accept the <c>$=</c> + character in environment variable names causing various + problems. <c>$=</c> characters in environment variable + names are now also <em>rejected</em>. </p> <p>Also + <seealso + marker="kernel:os#cmd/1"><c>os:cmd/1</c></seealso> now + reject null characters inside its <seealso + marker="kernel:os#type-os_command">command</seealso>. + </p> <p><seealso + marker="erts:erlang#open_port/2"><c>erlang:open_port/2</c></seealso> + will also reject null characters inside the port name + from now on.</p> + <p> + *** POTENTIAL INCOMPATIBILITY ***</p> + <p> + Own Id: OTP-14543 Aux Id: ERL-370 </p> + </item> + <item> + <p><c>os:putenv</c> and <c>os:getenv</c> no longer access + the process environment directly and instead work on a + thread-safe emulation. The only observable difference is + that it's <em>not</em> kept in sync with libc + <c>getenv(3)</c> / <c>putenv(3)</c>, so those who relied + on that behavior in drivers or NIFs will need to add + manual synchronization.</p> <p>On Windows this means that + you can no longer resolve DLL dependencies by modifying + the <c>PATH</c> just before loading the driver/NIF. To + make this less of a problem, the emulator now adds the + target DLL's folder to the DLL search path.</p> + <p> + *** POTENTIAL INCOMPATIBILITY ***</p> + <p> + Own Id: OTP-14666</p> + </item> + <item> + <p> + Fixed connection tick toward primitive hidden nodes + (erl_interface) that could cause faulty tick timeout in + rare cases when payload data is sent to hidden node but + not received.</p> + <p> + Own Id: OTP-14681</p> + </item> + <item> + <p> + Make group react immediately on an EXIT-signal from shell + in e.g ssh.</p> + <p> + Own Id: OTP-14991 Aux Id: PR1705 </p> + </item> + <item> + <p> + Calls to <c>gen_tcp:send/2</c> on closed sockets now + returns <c>{error, closed}</c> instead of + <c>{error,enotconn}</c>.</p> + <p> + Own Id: OTP-15001</p> + </item> + <item> + <p> + The <c>included_applications</c> key are no longer + duplicated as application environment variable. Earlier, + the included applications could be read both with + <c>application:get[_all]_env(...)</c> and + <c>application:get[_all]_key(...)</c> functions. Now, it + can only be read with + <c>application:get[_all]_key(...)</c>.</p> + <p> + *** POTENTIAL INCOMPATIBILITY ***</p> + <p> + Own Id: OTP-15071</p> + </item> + <item> + <p>Owner and group changes through + <c>file:write_file_info</c>, <c>file:change_owner</c>, + and <c>file:change_group</c> will no longer report + success on permission errors.</p> + <p> + *** POTENTIAL INCOMPATIBILITY ***</p> + <p> + Own Id: OTP-15118</p> + </item> + </list> + </section> + + + <section><title>Improvements and New Features</title> + <list> + <item> + <p>A new logging API is added to Erlang/OTP, see the + <seealso + marker="kernel:logger"><c>logger(3)</c></seealso> manual + page, and section <seealso + marker="kernel:logger_chapter">Logging</seealso> in the + Kernel User's Guide.</p> + <p>Calls to <c>error_logger</c> are automatically + redirected to the new API, and legacy error logger event + handlers can still be used. It is, however, recommended + to use the Logger API directly when writing new code.</p> + <p>Notice the following potential incompatibilities:</p> + <list> <item><p>Kernel configuration parameters + <c>error_logger</c> still works, but is overruled if the + default handler's output destination is configured with + Kernel configuration parameter <c>logger</c>.</p> <p>In + general, parameters for configuring error logger are + overwritten by new parameters for configuring + Logger.</p></item> <item><p>The concept of SASL error + logging is deprecated, meaning that by default the SASL + application does not affect which log events are + logged.</p> <p>By default, supervisor reports and crash + reports are logged by the default Logger handler started + by Kernel, and end up at the same destination (terminal + or file) as other standard log event from Erlang/OTP.</p> + <p>Progress reports are not logged by default, but can be + enabled by setting the primary log level to info, for + example with the Kernel configuration parameter + <c>logger_level</c>.</p> <p>To obtain backwards + compatibility with the SASL error logging functionality + from earlier releases, set Kernel configuration parameter + <c>logger_sasl_compatible</c> to <c>true</c>. This + prevents the default Logger handler from logging any + supervisor-, crash-, or progress reports. Instead, SASL + adds a separate Logger handler during application start, + which takes care of these log events. The SASL + configuration parameters <c>sasl_error_logger</c> and + <c>sasl_errlog_type</c> specify the destination (terminal + or file) and severity level to log for these + events.</p></item></list> + <p> + Since Logger is new in Erlang/OTP 21.0, we do reserve the + right to introduce changes to the Logger API and + functionality in patches following this release. These + changes might or might not be backwards compatible with + the initial version.</p> + <p> + *** POTENTIAL INCOMPATIBILITY ***</p> + <p> + Own Id: OTP-13295</p> + </item> + <item> + <p> + The function <c>inet:i/0</c> has been documented.</p> + <p> + Own Id: OTP-13713 Aux Id: PR-1645 </p> + </item> + <item> + <p> + Typespecs for <c>netns</c> and <c>bind_to_device</c> + options have been added to <c>gen_tcp</c>, <c>gen_udp</c> + and <c>gen_sctp</c> functions.</p> + <p> + Own Id: OTP-14359 Aux Id: PR-1816 </p> + </item> + <item> + <p> + New functionality for implementation of alternative + carriers for the Erlang distribution has been introduced. + This mainly consists of support for usage of distribution + controller processes (previously only ports could be used + as distribution controllers). For more information see + <seealso marker="erts:alt_dist#distribution_module">ERTS + User's Guide ➜ How to implement an Alternative Carrier + for the Erlang Distribution ➜ Distribution + Module</seealso>.</p> + <p> + Own Id: OTP-14459</p> + </item> + <item> + <p><c>seq_trace</c> labels may now be any erlang + term.</p> + <p> + Own Id: OTP-14899</p> + </item> + <item> + <p> + The SSL distribution protocol <c>-proto inet_tls</c> has + stopped setting the SSL option + <c>server_name_indication</c>. New verify funs for client + and server in <c>inet_tls_dist</c> has been added, not + documented yet, that checks node name if present in peer + certificate. Usage is still also yet to be documented.</p> + <p> + Own Id: OTP-14969 Aux Id: OTP-14465, ERL-598 </p> + </item> + <item> + <p> + Changed timeout of <c>gen_server</c> calls to <c>auth</c> + server from default 5 seconds to <c>infinity</c>.</p> + <p> + Own Id: OTP-15009 Aux Id: ERL-601 </p> + </item> + <item> + <p>The callback module passed as <c>-epmd_module</c> to + erl has been expanded to be able to do name and port + resolving.</p> <p>Documentation has also been added in + the <seealso + marker="kernel:erl_epmd"><c>erl_epmd</c></seealso> + reference manual and ERTS User's Guide <seealso + marker="erts:alt_disco">How to Implement an Alternative + Service Discovery for Erlang Distribution</seealso>.</p> + <p> + Own Id: OTP-15086 Aux Id: PR-1694 </p> + </item> + <item> + <p> + Included config file specified with relative path in + sys.config are now first searched for relative to the + directory of sys.config itself. If not found, it is also + searched for relative to the current working directory. + The latter is for backwards compatibility.</p> + <p> + Own Id: OTP-15137 Aux Id: PR-1838 </p> + </item> + </list> + </section> + +</section> + <section><title>Kernel 5.4.3.2</title> <section><title>Fixed Bugs and Malfunctions</title> diff --git a/lib/kernel/doc/src/os.xml b/lib/kernel/doc/src/os.xml index 7ce2f54542..c95e615c6b 100644 --- a/lib/kernel/doc/src/os.xml +++ b/lib/kernel/doc/src/os.xml @@ -4,7 +4,7 @@ <erlref> <header> <copyright> - <year>1997</year><year>2017</year> + <year>1997</year><year>2018</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> @@ -36,11 +36,85 @@ only run on a specific platform. On the other hand, with careful use, these functions can be of help in enabling a program to run on most platforms.</p> + + <note> + <p> + File operations used to accept filenames containing + null characters (integer value zero). This caused + the name to be truncated and in some cases arguments + to primitive operations to be mixed up. Filenames + containing null characters inside the filename + are now <em>rejected</em> and will cause primitive + file operations to fail. + </p> + <p> + Also environment variable operations used to accept + names and values of environment variables containing + null characters (integer value zero). This caused + operations to silently produce erroneous results. + Environment variable names and values containing + null characters inside the name or value are now + <em>rejected</em> and will cause environment variable + operations to fail. + </p> + </note> </description> <datatypes> <datatype> + <name name="env_var_name"/> + <desc> + <p>A string containing valid characters on the specific + OS for environment variable names using + <seealso marker="file#native_name_encoding/0"><c>file:native_name_encoding()</c></seealso> + encoding. Note that specifically null characters (integer + value zero) and <c>$=</c> characters are not allowed. + However, note that not all invalid characters necessarily + will cause the primitiv operations to fail, but may instead + produce invalid results. + </p> + </desc> + </datatype> + <datatype> + <name name="env_var_value"/> + <desc> + <p>A string containing valid characters on the specific + OS for environment variable values using + <seealso marker="file#native_name_encoding/0"><c>file:native_name_encoding()</c></seealso> + encoding. Note that specifically null characters (integer + value zero) are not allowed. However, note that not all + invalid characters necessarily will cause the primitiv + operations to fail, but may instead produce invalid results. + </p> + </desc> + </datatype> + <datatype> + <name name="env_var_name_value"/> + <desc> + <p> + Assuming that environment variables has been correctly + set, a strings containing valid characters on the specific + OS for environment variable names and values using + <seealso marker="file#native_name_encoding/0"><c>file:native_name_encoding()</c></seealso> + encoding. The first <c>$=</c> characters appearing in + the string separates environment variable name (on the + left) from environment variable value (on the right). + </p> + </desc> + </datatype> + <datatype> <name name="os_command"/> + <desc> + <p>All characters needs to be valid characters on the + specific OS using + <seealso marker="file#native_name_encoding/0"><c>file:native_name_encoding()</c></seealso> + encoding. Note that specifically null characters (integer + value zero) are not allowed. However, note that not all + invalid characters not necessarily will cause + <seealso marker="#cmd/1"><c>os:cmd/1</c></seealso> + to fail, but may instead produce invalid results. + </p> + </desc> </datatype> <datatype> <name name="os_command_opts"/> @@ -65,8 +139,13 @@ <fsummary>Execute a command in a shell of the target OS.</fsummary> <desc> <p>Executes <c><anno>Command</anno></c> in a command shell of the - target OS, captures the standard output of the command, + target OS, captures the standard output of the command, and returns this result as a string.</p> + <warning><p>Previous implementation used to allow all characters + as long as they were integer values greater than or equal to zero. + This sometimes lead to unwanted results since null characters + (integer value zero) often are interpreted as string termination. The + current implementation rejects these.</p></warning> <p><em>Examples:</em></p> <code type="none"> LsOut = os:cmd("ls"), % on unix platform @@ -185,6 +264,15 @@ DirOut = os:cmd("dir"), % on Win32 platform</code> <p>On Unix platforms, the environment is set using UTF-8 encoding if Unicode filename translation is in effect. On Windows, the environment is set using wide character interfaces.</p> + <note> + <p> + <c><anno>VarName</anno></c> is not allowed to contain + an <c>$=</c> character. Previous implementations used + to just let the <c>$=</c> character through which + silently caused erroneous results. Current implementation + will instead throw a <c>badarg</c> exception. + </p> + </note> </desc> </func> diff --git a/lib/kernel/doc/src/part.xml b/lib/kernel/doc/src/part.xml new file mode 100644 index 0000000000..fa7e92835f --- /dev/null +++ b/lib/kernel/doc/src/part.xml @@ -0,0 +1,37 @@ +<?xml version="1.0" encoding="utf-8" ?> +<!DOCTYPE part SYSTEM "part.dtd"> + +<part xmlns:xi="http://www.w3.org/2001/XInclude"> + <header> + <copyright> + <year>2018</year> + <holder>Ericsson AB. All Rights Reserved.</holder> + </copyright> + <legalnotice> + Licensed under the Apache License, Version 2.0 (the "License"); + you may not use this file except in compliance with the License. + You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + + Unless required by applicable law or agreed to in writing, software + distributed under the License is distributed on an "AS IS" BASIS, + WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + See the License for the specific language governing permissions and + limitations under the License. + + </legalnotice> + + <title>Kernel User's Guide</title> + <prepared>OTP Team</prepared> + <docno></docno> + <date>2018-06-06</date> + <file>part.xml</file> + </header> + <description> + <p></p> + </description> + <xi:include href="introduction_chapter.xml"/> + <xi:include href="logger_chapter.xml"/> +</part> + diff --git a/lib/kernel/doc/src/ref_man.xml b/lib/kernel/doc/src/ref_man.xml index 5cd77e0f6f..d3b947527f 100644 --- a/lib/kernel/doc/src/ref_man.xml +++ b/lib/kernel/doc/src/ref_man.xml @@ -4,7 +4,7 @@ <application xmlns:xi="http://www.w3.org/2001/XInclude"> <header> <copyright> - <year>1996</year><year>2016</year> + <year>1996</year><year>2018</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> @@ -32,12 +32,15 @@ </description> <xi:include href="kernel_app.xml"/> + <xi:include href="app.xml"/> <xi:include href="application.xml"/> <xi:include href="auth.xml"/> <xi:include href="code.xml"/> + <xi:include href="config.xml"/> <xi:include href="disk_log.xml"/> <xi:include href="erl_boot_server.xml"/> <xi:include href="erl_ddll.xml"/> + <xi:include href="erl_epmd.xml"/> <xi:include href="erl_prim_loader_stub.xml"/> <xi:include href="erlang_stub.xml"/> <xi:include href="error_handler.xml"/> @@ -52,6 +55,11 @@ <xi:include href="inet.xml"/> <xi:include href="inet_res.xml"/> <xi:include href="init_stub.xml"/> + <xi:include href="logger.xml"/> + <xi:include href="logger_filters.xml"/> + <xi:include href="logger_formatter.xml"/> + <xi:include href="logger_std_h.xml"/> + <xi:include href="logger_disk_log_h.xml"/> <xi:include href="net_adm.xml"/> <xi:include href="net_kernel.xml"/> <xi:include href="os.xml"/> @@ -61,6 +69,4 @@ <xi:include href="user.xml"/> <xi:include href="wrap_log_reader.xml"/> <xi:include href="zlib_stub.xml"/> - <xi:include href="app.xml"/> - <xi:include href="config.xml"/> </application> diff --git a/lib/kernel/doc/src/rpc.xml b/lib/kernel/doc/src/rpc.xml index adec2d9520..fab616e630 100644 --- a/lib/kernel/doc/src/rpc.xml +++ b/lib/kernel/doc/src/rpc.xml @@ -4,7 +4,7 @@ <erlref> <header> <copyright> - <year>1996</year><year>2016</year> + <year>1996</year><year>2018</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> @@ -217,7 +217,7 @@ <list type="bulleted"> <item>A list of the nodes that do not exist</item> <item>A list of the nodes where the server does not exist</item> - <item>A list of the nodes where the server terminatd before sending + <item>A list of the nodes where the server terminated before sending any reply.</item> </list> </desc> @@ -268,8 +268,9 @@ on the specified nodes and collects the answers. It returns <c>{<anno>ResL</anno>, <anno>BadNodes</anno>}</c>, where <c><anno>BadNodes</anno></c> is a list - of the nodes that terminated or timed out during computation, - and <c><anno>ResL</anno></c> is a list of the return values. + of the nodes that do not exist, + and <c><anno>ResL</anno></c> is a list of the return values, + or <c>{badrpc, <anno>Reason</anno>}</c> for failing calls. <c><anno>Timeout</anno></c> is a time (integer) in milliseconds, or <c>infinity</c>.</p> <p>The following example is useful when new object code is to @@ -347,7 +348,7 @@ <func> <name name="pmap" arity="3"/> - <fsummary>Parallell evaluation of mapping a function over a + <fsummary>Parallel evaluation of mapping a function over a list.</fsummary> <desc> <p>Evaluates <c>apply(<anno>Module</anno>, <anno>Function</anno>, diff --git a/lib/kernel/doc/src/seq_trace.xml b/lib/kernel/doc/src/seq_trace.xml index 197851021f..1a4a74419a 100644 --- a/lib/kernel/doc/src/seq_trace.xml +++ b/lib/kernel/doc/src/seq_trace.xml @@ -4,7 +4,7 @@ <erlref> <header> <copyright> - <year>1998</year><year>2017</year> + <year>1998</year><year>2018</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> @@ -80,13 +80,18 @@ seq_trace:set_token(OldToken), % activate the trace token again <p>Sets the individual <c><anno>Component</anno></c> of the trace token to <c><anno>Val</anno></c>. Returns the previous value of the component.</p> <taglist> - <tag><c>set_token(label, <anno>Integer</anno>)</c></tag> + <tag><c>set_token(label, <anno>Label</anno>)</c></tag> <item> - <p>The <c>label</c> component is an integer which + <p>The <c>label</c> component is a term which identifies all events belonging to the same sequential trace. If several sequential traces can be active simultaneously, <c>label</c> is used to identify the separate traces. Default is 0.</p> + <warning> + <p>Labels were restricted to small signed integers (28 bits) + prior to OTP 21. The trace token will be silenty dropped if it + crosses over to a node that does not support the label.</p> + </warning> </item> <tag><c>set_token(serial, SerialValue)</c></tag> <item> diff --git a/lib/kernel/doc/src/specs.xml b/lib/kernel/doc/src/specs.xml index 29d52f23bb..b8c25ca53b 100644 --- a/lib/kernel/doc/src/specs.xml +++ b/lib/kernel/doc/src/specs.xml @@ -6,6 +6,7 @@ <xi:include href="../specs/specs_disk_log.xml"/> <xi:include href="../specs/specs_erl_boot_server.xml"/> <xi:include href="../specs/specs_erl_ddll.xml"/> + <xi:include href="../specs/specs_erl_epmd.xml"/> <xi:include href="../specs/specs_erl_prim_loader_stub.xml"/> <xi:include href="../specs/specs_erlang_stub.xml"/> <xi:include href="../specs/specs_error_handler.xml"/> @@ -20,6 +21,11 @@ <xi:include href="../specs/specs_inet.xml"/> <xi:include href="../specs/specs_inet_res.xml"/> <xi:include href="../specs/specs_init_stub.xml"/> + <xi:include href="../specs/specs_logger.xml"/> + <xi:include href="../specs/specs_logger_filters.xml"/> + <xi:include href="../specs/specs_logger_formatter.xml"/> + <xi:include href="../specs/specs_logger_std_h.xml"/> + <xi:include href="../specs/specs_logger_disk_log_h.xml"/> <xi:include href="../specs/specs_net_adm.xml"/> <xi:include href="../specs/specs_net_kernel.xml"/> <xi:include href="../specs/specs_os.xml"/> |
