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authorSiri Hansen <[email protected]>2018-04-24 14:26:31 +0200
committerSiri Hansen <[email protected]>2018-04-26 14:37:30 +0200
commit0deea4a8f369013ec00e231d0c2c37e4ab3f0ba1 (patch)
tree054b8465a9eb07b07fde4596f2209ee1df689a92 /lib/kernel/doc
parent0183ddffb112d898d9b8c0396afa7f2210b9e169 (diff)
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Add logger
Diffstat (limited to 'lib/kernel/doc')
-rw-r--r--lib/kernel/doc/src/Makefile21
-rw-r--r--lib/kernel/doc/src/book.xml3
-rw-r--r--lib/kernel/doc/src/introduction_chapter.xml64
-rw-r--r--lib/kernel/doc/src/logger.xml478
-rw-r--r--lib/kernel/doc/src/logger_arch.pngbin0 -> 31459 bytes
-rw-r--r--lib/kernel/doc/src/logger_chapter.xml641
-rw-r--r--lib/kernel/doc/src/logger_filters.xml191
-rw-r--r--lib/kernel/doc/src/logger_formatter.xml149
-rw-r--r--lib/kernel/doc/src/logger_std_h.xml81
-rw-r--r--lib/kernel/doc/src/part.xml40
-rw-r--r--lib/kernel/doc/src/ref_man.xml4
-rw-r--r--lib/kernel/doc/src/specs.xml4
12 files changed, 1671 insertions, 5 deletions
diff --git a/lib/kernel/doc/src/Makefile b/lib/kernel/doc/src/Makefile
index 2413541082..10bdf46119 100644
--- a/lib/kernel/doc/src/Makefile
+++ b/lib/kernel/doc/src/Makefile
@@ -56,6 +56,10 @@ XML_REF3_FILES = application.xml \
inet.xml \
inet_res.xml \
init_stub.xml \
+ logger.xml \
+ logger_std_h.xml \
+ logger_filters.xml \
+ logger_formatter.xml \
net_adm.xml \
net_kernel.xml \
os.xml \
@@ -70,11 +74,17 @@ 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
+IMAGE_FILES = \
+ logger_arch.png
+
XML_FILES = \
$(BOOK_FILES) $(XML_CHAPTER_FILES) \
$(XML_PART_FILES) $(XML_REF3_FILES) $(XML_REF4_FILES)\
@@ -111,7 +121,7 @@ SPECS_FLAGS = -I../../include
# ----------------------------------------------------
# Targets
# ----------------------------------------------------
-$(HTMLDIR)/%.gif: %.gif
+$(HTMLDIR)/%: %
$(INSTALL_DATA) $< $@
docs: man pdf html
@@ -120,11 +130,12 @@ $(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:
diff --git a/lib/kernel/doc/src/book.xml b/lib/kernel/doc/src/book.xml
index 81a87d126d..0b69b547e7 100644
--- a/lib/kernel/doc/src/book.xml
+++ b/lib/kernel/doc/src/book.xml
@@ -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/introduction_chapter.xml b/lib/kernel/doc/src/introduction_chapter.xml
new file mode 100644
index 0000000000..6e6990ddda
--- /dev/null
+++ b/lib/kernel/doc/src/introduction_chapter.xml
@@ -0,0 +1,64 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<!DOCTYPE chapter SYSTEM "chapter.dtd">
+
+<chapter>
+ <header>
+ <copyright>
+ <year>2017</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>Error 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/logger.xml b/lib/kernel/doc/src/logger.xml
new file mode 100644
index 0000000000..66e6e5c689
--- /dev/null
+++ b/lib/kernel/doc/src/logger.xml
@@ -0,0 +1,478 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<!DOCTYPE erlref SYSTEM "erlref.dtd">
+
+<erlref>
+ <header>
+ <copyright>
+ <year>2017</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 the logger application.</modulesummary>
+
+ <description>
+
+ </description>
+
+ <datatypes>
+ <datatype>
+ <name name="level"/>
+ <desc>
+ <p>The severity level for the message to be logged.</p>
+ </desc>
+ </datatype>
+ <datatype>
+ <name name="log"/>
+ <desc>
+ <p></p>
+ </desc>
+ </datatype>
+ <datatype>
+ <name name="report"/>
+ <desc>
+ <p></p>
+ </desc>
+ </datatype>
+ <datatype>
+ <name name="msg_fun"/>
+ <desc>
+ <p></p>
+ </desc>
+ </datatype>
+ <datatype>
+ <name name="metadata"/>
+ <desc>
+ <p>Metadata associated with the message to be logged.</p>
+ </desc>
+ </datatype>
+ <datatype>
+ <name name="config"/>
+ <desc>
+ <p></p>
+ </desc>
+ </datatype>
+ <datatype>
+ <name name="handler_id"/>
+ <desc>
+ <p></p>
+ </desc>
+ </datatype>
+ <datatype>
+ <name name="filter_id"/>
+ <desc>
+ <p></p>
+ </desc>
+ </datatype>
+ <datatype>
+ <name name="filter"/>
+ <desc>
+ <p></p>
+ </desc>
+ </datatype>
+ <datatype>
+ <name name="filter_return"/>
+ <desc>
+ <p></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>
+ </list>
+
+ <p>All macros expand to a call to logger, where <c>Level</c> is
+ taken from the macro name, and the following metadata is added,
+ or merged with the given <c>Metadata</c>:</p>
+
+ <code>
+#{mfa=>{?MODULE,?FUNCTION_NAME,?FUNCTION_ARITY},
+ file=>?FILE,
+ line=>?LINE}
+ </code>
+
+ <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>
+
+ <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>
+
+ <func>
+ <name name="get_logger_config" arity="0"/>
+ <fsummary>Lookup the current configuration for logger.</fsummary>
+ <desc>
+ <p>Lookup the current configuration for logger.</p>
+ </desc>
+ </func>
+
+ <func>
+ <name name="get_handler_config" arity="1"/>
+ <fsummary>Lookup the current configuration for the given handler.</fsummary>
+ <desc>
+ <p>Lookup the current configuration for the given handler.</p>
+ </desc>
+ </func>
+
+ <func>
+ <name name="i" arity="0"/>
+ <fsummary>Get information about all logger configurations</fsummary>
+ <desc>
+ <p>Same as <seealso marker="#i/1"><c>logger:i(term)</c></seealso></p>
+ </desc>
+ </func>
+
+ <func>
+ <name name="i" arity="1" clause_i="1"/>
+ <name name="i" arity="1" clause_i="2"/>
+ <name name="i" arity="1" clause_i="3"/>
+ <fsummary>Get information about all logger configurations</fsummary>
+ <desc>
+ <p>The <c>logger:i/1</c> function can be used to get all
+ current logger configuration. The way that the information
+ is returned depends on the <c><anno>Action</anno></c></p>
+ <taglist>
+ <tag>string</tag>
+ <item>Return the pretty printed current logger configuration
+ as iodata.</item>
+ <tag>term</tag>
+ <item>Return the current logger configuration as a term. The
+ format of this term may change inbetween releases. For a
+ stable format use <seealso marker="#get_handler_config/1">
+ <c>logger:get_handler_config/1</c></seealso>
+ and <seealso marker="#get_logger_config/0">
+ <c>logger:get_logger_config/0</c></seealso>.
+ The same as calling <c>logger:i()</c>.</item>
+ <tag>print</tag>
+ <item>Pretty print all the current logger configuration to
+ standard out. Example:
+ <code><![CDATA[1> logger:i().
+Current logger configuration:
+ Level: info
+ FilterDefault: log
+ Filters:
+ Handlers:
+ Id: logger_std_h
+ Module: logger_std_h
+ Level: info
+ Formatter:
+ Module: logger_formatter
+ Config: #{template => [{logger_formatter,header},"\n",msg,"\n"],
+ legacy_header => true}
+ Filter Default: stop
+ Filters:
+ Id: stop_progress
+ Fun: fun logger_filters:progress/2
+ Config: stop
+ Id: remote_gl
+ Fun: fun logger_filters:remote_gl/2
+ Config: stop
+ Id: domain
+ Fun: fun logger_filters:domain/2
+ Config: {log,prefix_of,[beam,erlang,otp,sasl]}
+ Id: no_domain
+ Fun: fun logger_filters:domain/2
+ Config: {log,no_domain,[]}
+ Handler Config:
+ logger_std_h: #{type => standard_io}
+ Level set per module:
+ Module: my_module
+ Level: debug]]></code>
+ </item>
+ </taglist>
+ </desc>
+ </func>
+
+ <func>
+ <name name="add_logger_filter" arity="2"/>
+ <fsummary>Add a filter to the logger.</fsummary>
+ <desc>
+ <p>Add a filter to the logger.</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>
+ </desc>
+ </func>
+
+ <func>
+ <name name="remove_logger_filter" arity="1"/>
+ <fsummary>Remove a filter from the logger.</fsummary>
+ <desc>
+ <p>Remove the filter with the specified identity from the logger.</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 with the specified identity from the given handler.</p>
+ </desc>
+ </func>
+
+ <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>
+ </desc>
+ </func>
+
+ <func>
+ <name name="remove_handler" arity="1"/>
+ <fsummary>Remove the handler with the specified identity.</fsummary>
+ <desc>
+ <p>Remove the handler with the specified identity.</p>
+ </desc>
+ </func>
+
+ <func>
+ <name name="set_module_level" arity="2"/>
+ <fsummary>Set the log level for the specified module.</fsummary>
+ <desc>
+ <p>Set the log level for the specified module.</p>
+ <p>To change the logging level globally, use
+ <seealso marker="#set_logger_config/2"><c>logger:set_logger_config(level, Level)</c></seealso>.
+ </p>
+ </desc>
+ </func>
+
+ <func>
+ <name name="reset_module_level" arity="1"/>
+ <fsummary>Remove a module specific log setting.</fsummary>
+ <desc>
+ <p>Remove a module specific log setting. After this, the
+ global log level is used for the specified module.</p>
+ </desc>
+ </func>
+
+ <func>
+ <name name="set_logger_config" arity="1"/>
+ <name name="set_logger_config" arity="2"/>
+ <fsummary>Add or update configuration data for the logger.</fsummary>
+ <desc>
+ <p>Add or update configuration data for the logger.</p>
+ </desc>
+ </func>
+
+ <func>
+ <name name="set_handler_config" arity="2"/>
+ <name name="set_handler_config" arity="3"/>
+ <fsummary>Add or update configuration data for the specified
+ handler.</fsummary>
+ <desc>
+ <p>Add or update configuration data for the specified
+ handler.</p>
+ </desc>
+ </func>
+
+ <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="set_process_metadata" arity="1"/>
+ <fsummary>Set metadata to use when logging from current process.</fsummary>
+ <desc>
+ <p>Set metadata which <c>logger</c> automatically inserts it
+ in all log events produced on the current
+ process. Subsequent calls will overwrite previous data set
+ by this function.</p>
+ <p>When logging, location data produced by the log macros,
+ and/or metadata given as argument to the log call (API
+ function or macro), will be merged with the process
+ metadata. If the same keys occur, values from the metadata
+ argument to the log call will overwrite values in the
+ process metadata, which in turn will overwrite values from
+ the location data.</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>.</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>.</p>
+ </desc>
+ </func>
+
+ </funcs>
+
+</erlref>
+
+
diff --git a/lib/kernel/doc/src/logger_arch.png b/lib/kernel/doc/src/logger_arch.png
new file mode 100644
index 0000000000..727609a6ef
--- /dev/null
+++ b/lib/kernel/doc/src/logger_arch.png
Binary files differ
diff --git a/lib/kernel/doc/src/logger_chapter.xml b/lib/kernel/doc/src/logger_chapter.xml
new file mode 100644
index 0000000000..2a325453da
--- /dev/null
+++ b/lib/kernel/doc/src/logger_chapter.xml
@@ -0,0 +1,641 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<!DOCTYPE chapter SYSTEM "chapter.dtd">
+
+<chapter>
+ <header>
+ <copyright>
+ <year>2017</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>
+
+ <section>
+ <title>Overview</title>
+ <p>Erlang/OTP provides a standard API for logging. The backend of
+ this API can be used as is, or it can be customized to suite
+ specific needs.</p>
+ <p>It consists of two parts - the <em>logger</em> part and the
+ <em>handler</em> part. The logger will forward log events to one
+ or more handler(s).</p>
+
+ <image file="logger_arch.png">
+ <icaption>Conceptual overview</icaption>
+ </image>
+
+ <p><em>Filters</em> can be added to the logger and to each
+ handler. The filters decide if an event is to be forwarded or
+ not, and they can also modify all parts of the log event.</p>
+
+ <p>A <em>formatter</em> can be set for each handler. The formatter
+ does the final formatting of the log event, including the log
+ message itself, and possibly a timestamp, header and other
+ metadata.</p>
+
+ <p>In accordance with the Syslog protocol, RFC-5424, eight
+ severity levels can be specified:</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 contidions</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>Severity levels</tcaption>
+ </table>
+
+ <p>A log event is allowed by Logger if the integer value of
+ its <c>Level</c> is less than or equal to the currently
+ configured log level. The log level can be configured globally,
+ or to allow more verbose logging from a specific part of the
+ system, per module.</p>
+
+ <section>
+ <title>Customizable parts</title>
+
+ <taglist>
+ <tag><marker id="Handler"/>Handler</tag>
+ <item>
+ <p>A handler is defined as a module exporting the following
+ function:</p>
+
+ <code>log(Log, Config) -> ok</code>
+
+ <p>A handler is called by the logger backend after filtering on
+ logger level and on handler level for the handler which is
+ about to be called. The function call is done on the client
+ process, and it is up to the handler implementation if other
+ processes are to be involved or not.</p>
+
+ <p>Multiple instances of the same handler can be
+ added. Configuration is per instance.</p>
+
+ </item>
+
+ <tag><marker id="Filter"/>Filter</tag>
+ <item>
+ <p>Filters can be set on the logger or on a handler. Logger
+ filters are applied first, and if passed, the handler filters
+ for each handler are applied. The handler plugin is only
+ called if all handler filters for the handler in question also
+ pass.</p>
+
+ <p>A filter is specified as:</p>
+
+ <code>{fun((Log,Extra) -> Log | stop | ignore), Extra}</code>
+
+ <p>The configuration parameter <c>filter_default</c>
+ specifies the behavior if all filters return <c>ignore</c>.
+ <c>filter_default</c> is by default set to <c>log</c>.</p>
+
+ <p>The <c>Extra</c> parameter may contain any data that the
+ filter needs.</p>
+ </item>
+
+ <tag><marker id="Formatter"/>Formatter</tag>
+ <item>
+ <p>A formatter is defined as a module exporting the following
+ function:</p>
+
+ <code>format(Log,Extra) -> string()</code>
+
+ <p>The formatter plugin is called by each handler, and the
+ returned string can be printed to the handler's destination
+ (stdout, file, ...).</p>
+ </item>
+
+ </taglist>
+ </section>
+
+ <section>
+ <title>Built-in handlers</title>
+
+ <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, console or file. Filters can be used for
+ selecting which event to send to which handler instance.</p>
+ </item>
+
+ <tag><c>logger_disk_log_h</c></tag>
+ <item>
+ <p>This handler behaves much like logger_std_h, 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 to be used for backwards compatibility
+ only. It is not started by default, but will be automatically
+ started the first time an 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>No built-in event handlers exist.</p>
+ </item>
+ </taglist>
+ </section>
+
+ <section>
+ <title>Built-in filters</title>
+
+ <taglist>
+ <tag><c>logger_filters:domain/2</c></tag>
+ <item>
+ <p>This filter provides a way of filtering log events based on a
+ <c>domain</c> field <c>Metadata</c>. See
+ <seealso marker="logger_filters#domain-2">
+ <c>logger_filters:domain/2</c></seealso></p>
+ </item>
+
+ <tag><c>logger_filters:level/2</c></tag>
+ <item>
+ <p>This filter provides a way of filtering log events based
+ on the log level. See <seealso marker="logger_filters#domain-2">
+ <c>logger_filters:domain/2</c></seealso></p>
+ </item>
+
+ <tag><c>logger_filters:progress/2</c></tag>
+ <item>
+ <p>This filter matches all progress reports
+ from <c>supervisor</c> and <c>application_controller</c>.
+ See <seealso marker="logger_filters#progress/2">
+ <c>logger_filters:progress/2</c></seealso></p>
+ </item>
+
+ <tag><c>logger_filters:remote_gl/2</c></tag>
+ <item>
+ <p>This filter matches all events originating from a process
+ that has its group leader on a remote node.
+ See <seealso marker="logger_filters#remote_gl/2">
+ <c>logger_filters:remote_gl/2</c></seealso></p>
+ </item>
+ </taglist>
+ </section>
+
+ <section>
+ <title>Default formatter</title>
+
+ <p>The default formatter is <c>logger_formatter</c>.
+ See <seealso marker="logger_formatter#format-2">
+ <c>logger_formatter:format/2</c></seealso>.</p>
+ </section>
+ </section>
+
+ <section>
+ <title>Configuration</title>
+
+ <section>
+ <title>Application environment variables</title>
+ <p>See <seealso marker="kernel_app#configuration">Kernel(6)</seealso> for
+ information about the application environment variables that can
+ be used for configuring logger.</p>
+ </section>
+
+ <section>
+ <title>Logger configuration</title>
+
+ <taglist>
+ <tag><c>level</c></tag>
+ <item>
+ <p>Specifies the severity level to log.</p>
+ </item>
+ <tag><c>filters</c></tag>
+ <item>
+ <p>Logger filters are added or removed with
+ <seealso marker="logger#add_logger_filter-2">
+ <c>logger:add_logger_filter/2</c></seealso> and
+ <seealso marker="logger#remove_logger_filter-1">
+ <c>logger:remove_logger_filter/1</c></seealso>,
+ respectively.</p>
+ <p>See <seealso marker="#Filter">Filter</seealso> for more
+ information.</p>
+ <p>By default, no filters exist.</p>
+ </item>
+ <tag><c>filter_default = log | stop</c></tag>
+ <item>
+ <p>Specifies what to do with an event if all filters
+ return <c>ignore</c>.</p>
+ <p>Default is <c>log</c>.</p>
+ </item>
+ <tag><c>handlers</c></tag>
+ <item>
+ <p>Handlers are added or removed with
+ <seealso marker="logger#add_handler-3">
+ <c>logger:add_handler/3</c></seealso> and
+ <seealso marker="logger#remove_handler-1">
+ <c>logger:remove_handler/1</c></seealso>,
+ respectively.</p>
+ <p>See <seealso marker="#Handler">Handler</seealso> for more
+ information.</p>
+ </item>
+ </taglist>
+ </section>
+
+ <section>
+ <title>Handler configuration</title>
+ <taglist>
+ <tag><c>level</c></tag>
+ <item>
+ <p>Specifies the severity level to log.</p>
+ </item>
+ <tag><c>filters</c></tag>
+ <item>
+ <p>Handler filters can be specified when adding the handler,
+ or added or removed later 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="#Filter">Filter</seealso> for more
+ information.</p>
+ <p>By default, no filters exist.</p>
+ </item>
+ <tag><c>filter_default = log | stop</c></tag>
+ <item>
+ <p>Specifies what to do with an event if all filters
+ return <c>ignore</c>.</p>
+ <p>Default is <c>log</c>.</p>
+ </item>
+ <tag><c>depth = pos_integer() | unlimited</c></tag>
+ <item>
+ <p>Specifies if the depth of terms in the log events shall
+ be limited by using control characters <c>~P</c>
+ and <c>~W</c> instead of <c>~p</c> and <c>~w</c>,
+ respectively. See
+ <seealso marker="stdlib:io#format-1"><c>io:format</c></seealso>.</p>
+ </item>
+ <tag><c>max_size = pos_integer() | unlimited</c></tag>
+ <item>
+ <p>Specifies if the size of a log event shall be limited by
+ truncating the formatted string.</p>
+ </item>
+ <tag><c>formatter = {Module::module(),Extra::term()}</c></tag>
+ <item>
+ <p>See <seealso marker="#Formatter">Formatter</seealso> for more
+ information.</p>
+ <p>The default module is <seealso marker="logger_formatter">
+ <c>logger_formatter</c></seealso>, and <c>Extra</c> is
+ it's configuration map.</p>
+ </item>
+ </taglist>
+
+ <p>Note that <c>level</c> and <c>filters</c> are obeyed by
+ Logger itself before forwarding the log events to each
+ handler, while <c>depth</c>, <c>max_size</c>
+ and <c>formatter</c> are left to the handler
+ implementation. All Logger's built-in handlers do apply these
+ configuration parameters before printing.</p>
+ </section>
+
+ </section>
+
+ <section>
+ <marker id="compatibility"/>
+ <title>Backwards compatibility with error_logger</title>
+ <p>Logger provides backwards compatibility with the old
+ <c>error_logger</c> in the following ways:</p>
+
+ <taglist>
+ <tag>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 will automatically start the <c>error_logger</c>
+ event manager, and add <c>error_logger</c> as a
+ handler to <c>logger</c>, with configuration</p>
+<code>
+#{level=>info,
+ filter_default=>log,
+ filters=>[]}.
+</code>
+ <p>Note that this handler will ignore events that do not
+ originate from the old <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>Also note that <c>error_logger</c> is not overload
+ protected.</p>
+ </item>
+ <tag>Logger API</tag>
+ <item>
+ <p>The old <c>error_logger</c> API still exists, but should
+ only be used by legacy code. It will be removed in a later
+ release.</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=>true</c>. This is
+ also the default.</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>SASL reports</tag>
+ <item>
+ <p>By SASL reports we mean supervisor reports, crash reports
+ and progress reports.</p>
+ <p>In earlier releases, these reports were only logged when
+ the SASL application was running, and they were printed
+ trough specific event handlers
+ named <c>sasl_report_tty_h</c>
+ and <c>sasl_report_file_h</c>.</p>
+ <p>The destination of these log events were configured by
+ environment variables for the SASL application.</p>
+ <p>Due to the specific event handlers, the output format
+ slightly differed from other log events.</p>
+ <p>As of OTP-21, the concept of SASL reports is removed,
+ meaning that the default behavior 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 logged by
+ default.</item>
+ <item>Progress reports are not logged by default, but can be
+ enabled with the kernel environment
+ variable <c>logger_log_progress</c>.</item>
+ <item>The output format is the same for all log
+ events.</item>
+ </list>
+ <p>If the old behavior is preferred, the kernel environment
+ variable <c>logger_sasl_compatible</c> can be set
+ to <c>true</c>. The old SASL environment variables 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_h</c>.</p>
+ <p>All SASL reports have a metadata
+ field <c>domain=>[beam,erlang,otp,sasl]</c>, which can be
+ used, for example, by filters to to stop or allow the
+ events.</p>
+ </item>
+ </taglist>
+ </section>
+
+
+ <section>
+ <title>Error handling</title>
+ <p>Log data is expected to be either a format string and
+ arguments, a string (unicode:chardata), or a report (map or
+ key-value list) which can be converted to a format string and
+ arguments by the handler. A default report callback should be
+ included in the log event's metadata, which can be used for
+ converting the report to a format string and arguments. The
+ handler might also do a custom conversion if the default format
+ is not desired.</p>
+ <p><c>logger</c> does, to a certain extent, check its input data
+ before forwarding a log event to the handlers, but it does not
+ evaluate conversion funs or check the validity of format strings
+ and arguments. This means that any filter or handler 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 then
+ print a short error message on the console. A debug event
+ containing the crash reason and other details is also issued,
+ and can be seen if a handler is installed which logs on debug
+ level.</p>
+ </section>
+
+ <section>
+ <title>Example: add a handler to log debug events to file</title>
+ <p>When starting an erlang node, the default behavior is that all
+ log events with level info and above are logged to the
+ console. In order to also log debug events, you can either
+ change the global log level to <c>debug</c> or add a separate
+ handler to take care of this. In this example we will add a new
+ handler which prints the debug events to a separate file.</p>
+ <p>First, we add an instance of logger_std_h with
+ type <c>{file,File}</c>, and we set the handler's level
+ to <c>debug</c>:</p>
+ <pre>
+1> <input>Config = #{level=>debug,logger_std_h=>#{type=>{file,"./debug.log"}}}.</input>
+#{logger_std_h => #{type => {file,"./debug.log"}},
+ level => debug}
+2> <input>logger:add_handler(debug_handler,logger_std_h,Config).</input>
+ok</pre>
+ <p>By default, the handler receives all events, so we need to add a filter
+ to stop all non-debug events:</p>
+ <pre>
+3> <input>Fun = fun(#{level:=debug}=Log,_) -> Log; (_,_) -> stop end.</input>
+#Fun&lt;erl_eval.12.98642416>
+4> <input>logger:add_handler_filter(debug_handler,allow_debug,{Fun,[]}).</input>
+ok</pre>
+ <p>And finally, we need to make sure that the logger itself allows
+ debug events. This can either be done by setting the global
+ logger level:</p>
+ <pre>
+5> <input>logger:set_logger_config(level,debug).</input>
+ok</pre>
+ <p>Or by allowing debug events from one or a few modules only:</p>
+ <pre>
+6> <input>logger:set_module_level(mymodule,debug).</input>
+ok</pre>
+
+ </section>
+
+ <section>
+ <title>Example: implement a handler</title>
+ <p>The only requirement that a handler MUST fulfill is to export
+ the following function:</p>
+ <code>log(logger:log(),logger:config()) ->ok</code>
+ <p>It may also implement the following callbacks:</p>
+ <code>
+adding_handler(logger:handler_id(),logger:config()) -> {ok,logger:config()} | {error,term()}
+removing_handler(logger:handler_id()) -> ok
+changing_config(logger:handler_id(),logger:config(),logger:config()) -> {ok,logger:config()} | {error,term()}
+ </code>
+ <p>When logger:add_handler(Id,Module,Config) is called, logger
+ will first call Module:adding_handler(Id,Config), and if it
+ returns {ok,NewConfig} the NewConfig is written to the
+ configuration database. After this, the handler may receive log
+ events as calls to Module:log/2.</p>
+ <p>A handler can be removed by calling
+ logger:remove_handler(Id). logger will call
+ Module:removing_handler(Id), and then remove the handler's
+ configuration from the configuration database.</p>
+ <p>When logger:set_handler_config is called, logger calls
+ Module:changing_config(Id,OldConfig,NewConfig). If this function
+ returns ok, the NewConfig is written to the configuration
+ database.</p>
+
+ <p>A simple handler which prints to the console could be
+ implemented as follows:</p>
+ <code>
+-module(myhandler).
+-export([log/2]).
+
+log(#{msg:={report,R}},_) ->
+ io:format("~p~n",[R]);
+log(#{msg:={string,S}},_) ->
+ io:put_chars(S);
+log(#{msg:={F,A}},_) ->
+ io:format(F,A).
+ </code>
+
+ <p>A simple handler which prints to file could be implemented like
+ this:</p>
+ <code>
+-module(myhandler).
+-export([adding_handler/2, removing_handler/1, log/2]).
+-export([init/1, handle_call/3, handle_cast/2, terminate/2]).
+
+adding_handler(Id,Config) ->
+ {ok,Fd} = file:open(File,[append,{encoding,utf8}]),
+ {ok,Config#{myhandler_fd=>Fd}}.
+
+removing_handler(Id,#{myhandler_fd:=Fd}) ->
+ _ = file:close(Fd),
+ ok.
+
+log(#{msg:={report,R}},#{myhandler_fd:=Fd}) ->
+ io:format(Fd,"~p~n",[R]);
+log(#{msg:={string,S}},#{myhandler_fd:=Fd}) ->
+ io:put_chars(Fd,S);
+log(#{msg:={F,A}},#{myhandler_fd:=Fd}) ->
+ io:format(Fd,F,A).
+ </code>
+
+ <p>Note that none of the above handlers have any overload
+ protection, and all log events are printed directly from the
+ client process. Neither do the handlers use the formatter or
+ in any way add time or other metadata to the printed events.</p>
+
+ <p>For examples of overload protection, please refer to 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>Below is a simpler example of a handler which logs through one
+ single process, and uses the default formatter to gain a common
+ look of the log events.</p>
+ <p>It also uses the metadata field <c>report_cb</c>, if it exists,
+ to print reports in the way the event issuer suggests. The
+ formatter will normally do this, but if the handler either has
+ an own default (as in this example) or if the
+ given <c>report_cb</c> should not be used at all, then the
+ handler must take care of this itself.</p>
+ <code>
+-module(myhandler).
+-export([adding_handler/2, removing_handler/1, log/2]).
+-export([init/1, handle_call/3, handle_cast/2, terminate/2]).
+
+adding_handler(Id,Config) ->
+ {ok,Pid} = gen_server:start(?MODULE,Config),
+ {ok,Config#{myhandler_pid=>Pid}}.
+
+removing_handler(Id,#{myhandler_pid:=Pid}) ->
+ gen_server:stop(Pid).
+
+log(Log,#{myhandler_pid:=Pid} = Config) ->
+ gen_server:cast(Pid,{log,Log,Config}).
+
+init(#{myhandler_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,Log,Config},#{fd:=Fd} = State) ->
+ do_log(Fd,Log,Config),
+ {noreply,State}.
+
+terminate(Reason,#{fd:=Fd}) ->
+ _ = file:close(Fd),
+ ok.
+
+do_log(Fd,#{msg:={report,R}} = Log, Config) ->
+ Fun = maps:get(report_cb,Config,fun my_report_cb/1,
+ {F,A} = Fun(R),
+ do_log(Fd,Log#{msg=>{F,A},Config);
+do_log(Fd,Log,#{formatter:={FModule,FConfig}}) ->
+ String = FModule:format(Log,FConfig),
+ io:put_chars(Fd,String).
+
+my_report_cb(R) ->
+ {"~p",[R]}.
+ </code>
+ </section>
+
+
+ <section>
+ <title>See Also</title>
+ <p><seealso marker="error_logger"><c>error_logger(3)</c></seealso>,
+ <seealso marker="sasl:sasl_app"><c>SASL(6)</c></seealso></p>
+ </section>
+</chapter>
diff --git a/lib/kernel/doc/src/logger_filters.xml b/lib/kernel/doc/src/logger_filters.xml
new file mode 100644
index 0000000000..d742391e35
--- /dev/null
+++ b/lib/kernel/doc/src/logger_filters.xml
@@ -0,0 +1,191 @@
+<?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>Filters to use with logger. All functions exported from this
+ module can be used as logger or handler
+ filters. See <seealso marker="logger#add_logger_filter-2">
+ <c>logger:add_logger_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>
+ </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 <c>Metadata</c>.</p>
+
+ <p>The <c><anno>Extra</anno></c> parameter is specified when
+ adding the filter
+ via <seealso marker="logger#add_logger_filter-2">
+ <c>logger:add_logger_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>)
+ to <c><anno>MatchDomain</anno></c> as follows:</p>
+
+ <taglist>
+ <tag><c><anno>Compare</anno> = starts_with</c></tag>
+ <item><p>The filter matches if <c>MatchDomain</c> is a prefix
+ of <c>Domain</c>.</p></item>
+ <tag><c><anno>Compare</anno> = prefix_of</c></tag>
+ <item><p>The filter matches if <c>Domain</c> is a prefix
+ of <c>MatchDomain</c>.</p></item>
+ <tag><c><anno>Compare</anno> = equals</c></tag>
+ <item><p>The filter matches if <c>Domain</c> is equal
+ to <c>MatchDomain</c>.</p></item>
+ <tag><c><anno>Compare</anno> = no_domain</c></tag>
+ <item><p>The filter matches if there is no domain field in
+ metadata. In this case <c><anno>MatchDomain</anno></c> shall
+ be <c>[]</c>.</p></item>
+ </taglist>
+
+ <p>If the filter matches and <c><anno>Action</anno> =
+ log</c>, the log event is allowed. If the filter matches
+ and <c><anno>Action</anno> = 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>Log events that do not contain any domain field, will
+ only match when <c><anno>Compare</anno> = no_domain</c>.</p>
+
+ <p>Example: stop all events with
+ domain <c>[beam,erlang,otp,sasl|_]</c></p>
+
+ <code>
+logger:set_handler_config(h1,filter_default,log). % this is the default
+Filter = {fun logger_filters:domain/2,{stop,starts_with,[beam,erlang,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 predefined <c>MatchLevel</c></p>
+
+ <p>The <c><anno>Extra</anno></c> parameter is specified when
+ adding the filter
+ via <seealso marker="logger#add_logger_filter-2">
+ <c>logger:add_logger_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) -> CmpRet</c></seealso>. It
+ matches the event if:</p>
+
+ <list>
+ <item><c>CmpRet = eq</c> and <c><anno>Operator</anno> =
+ eq | lteq | gteq</c></item>
+ <item><c>CmpRet = lt</c> and <c><anno>Operator</anno> =
+ lt | lteq | neq</c></item>
+ <item><c>CmpRet = gt</c> and <c><anno>Operator</anno> =
+ gt | gteq | neq</c></item>
+ </list>
+
+ <p>If the filter matches and <c><anno>Action</anno> =
+ log</c>, the log event is allowed. If the filter matches
+ and <c><anno>Action</anno> = 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> = log</c>, the progress reports
+ are allowed. If <c><anno>Extra</anno> = 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> = log</c>, the matching events
+ are allowed. If <c><anno>Extra</anno> = stop</c>, the
+ matching events are stopped.</p>
+
+ <p>The filter returns <c>ignore</c> for all other log events.</p>
+ </desc>
+ </func>
+
+ </funcs>
+
+</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..213a592e47
--- /dev/null
+++ b/lib/kernel/doc/src/logger_formatter.xml
@@ -0,0 +1,149 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<!DOCTYPE erlref SYSTEM "erlref.dtd">
+
+<erlref>
+ <header>
+ <copyright>
+ <year>2017</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 the Logger application.</modulesummary>
+
+ <description>
+ <p>Default formatter for the Logger application.</p>
+ </description>
+
+ <datatypes>
+ <datatype>
+ <name name="template"/>
+ <desc>
+ </desc>
+ </datatype>
+ </datatypes>
+
+ <funcs>
+ <func>
+ <name name="format" arity="2"/>
+ <fsummary>Formats the given message.</fsummary>
+ <desc>
+ <p>Formats the given message.</p>
+ <p>The template is a list of atoms, tuples and strings. Atoms
+ can be <c>level</c> or <c>msg</c>, which are placeholders
+ for the severity level and the log message,
+ repectively. Tuples are interpreted as placeholders for
+ metadata. Each element in the tuple must be an atom which
+ matches a key in the nested metadata map, e.g. the
+ tuple <c>{key1,key2}</c> will be replaced by the value of
+ the key2 field in this nested map (the value vill be
+ converted to a string):</p>
+
+<code>
+#{key1=>#{key2=>my_value,
+ ...},
+ ...}</code>
+
+
+ <p> Strings are printed literally.</p>
+
+ <p><c>depth</c> is 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">io:format/2</seealso>
+ in STDLIB.</p>
+
+ <p><c>max_size</c> is a positive integer representing the
+ maximum size a string returned from this formatter can
+ have. If the formatted string is longer, it will be
+ truncated.</p>
+
+ <p><c>utc</c> is a boolean. If set to true, all dates are
+ displayed in Universal Coordinated Time. Default
+ is <c>false</c>.</p>
+
+ <p><c>report_cb</c> must be a function with arity 1,
+ returning <c>{Format,Args}</c>. This function will replace
+ any <c>report_cb</c> found in metadata.</p>
+
+ <p>If <c>single_line=true</c>, all newlines in the message are
+ replaced with <c>", "</c>, and whitespaces following directly
+ after newlines are removed. Note that newlines added by the
+ formatter template are not replaced.</p>
+
+ <p>If <c>legacy_header=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 <c>error_logger</c> event handlers. It can be included
+ in the log event by adding the
+ tuple <c>{logger_formatter,header}</c> to the template.</p>
+
+ <p>The default template when <c>legacy_header=true</c> is</p>
+
+ <code>[{logger_formatter,header},"\n",msg,"\n"]</code>
+
+ <p>which will cause log entries like this:</p>
+
+ <code>=ERROR REPORT==== 29-Dec-2017::13:30:51.245123 ===
+ process: &lt;0.74.0&gt;
+ exit_reason: "Something went wrong"</code>
+
+ <p>Note that all eight levels might occur here, not
+ only <c>ERROR</c>, <c>WARNING</c> or <c>INFO</c>. And also
+ that micro seconds are added at the end of the
+ timestamp.</p>
+
+ <p>The default template when <c>single_line=true</c> is</p>
+
+ <code>[time," ",level,": ",msg,"\n"]</code>
+
+ <p>which will cause log entries like this:</p>
+
+ <code>2017-12-29 13:31:49.640317 error: process: &lt;0.74.0&gt;, exit_reason: "Something went wrong"</code>
+
+ <p>The default template when both <c>legacy_header</c> and
+ <c>single_line</c> are set to false is:</p>
+
+ <code>[time," ",level,":\n",msg,"\n"]</code>
+
+ <p>which will cause log entries like this:</p>
+
+ <code>2017-12-29 13:32:25.191925 error:
+ process: &lt;0.74.0&gt;
+ exit_reason: "Something went wrong"</code>
+
+ </desc>
+ </func>
+
+ </funcs>
+
+</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..2a368b16eb
--- /dev/null
+++ b/lib/kernel/doc/src/logger_std_h.xml
@@ -0,0 +1,81 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<!DOCTYPE erlref SYSTEM "erlref.dtd">
+
+<erlref>
+ <header>
+ <copyright>
+ <year>2017</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>Default handler for the Logger application.</modulesummary>
+
+ <description>
+ <p>This is the default handler for the Logger
+ application. Multiple instances of this handler can be added to
+ logger, and each instance will print logs to <c>standard_io</c>,
+ <c>standard_error</c> or to a file.</p>
+
+ <p>To add a new instance,
+ use <seealso marker="logger#add_handler-3"><c>logger:add_handler/3</c>
+ </seealso>.</p>
+
+ <p>The handler configuration may contain the following keys,
+ associated with values as described:</p>
+ <taglist>
+ <tag><c>filters</c></tag>
+ <item>
+ <p>A list of <c>{Id,{Fun,Args}}</c>, each representing a filter
+ that may selct or modify log events to forward to this
+ handler.</p></item>
+ <tag><c>filter_default</c></tag>
+ <item>
+ <p>The atom <c>log</c> or <c>stop</c>, specifying what to
+ do with a log event if all filters
+ return <c>ignore</c>.</p></item>
+ <tag><c>formatter</c></tag>
+ <item>
+ <p><c>{Module,Extra}</c>,
+ where <c>Module:format(Log,Extra)</c> will be called by
+ the handler to produce the string that will be printed to
+ the handler's destination.</p></item>
+ <tag><c>level</c></tag>
+ <item>
+ <p>The level of log events that <c>logger</c> shall forward to
+ this handler. Log events of the specified, or more severe
+ levels, are forwarded.</p></item>
+ </taglist>
+
+ </description>
+
+<!-- <funcs>
+ </funcs> -->
+
+</erlref>
+
+
diff --git a/lib/kernel/doc/src/part.xml b/lib/kernel/doc/src/part.xml
new file mode 100644
index 0000000000..68eb4530e2
--- /dev/null
+++ b/lib/kernel/doc/src/part.xml
@@ -0,0 +1,40 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<!DOCTYPE part SYSTEM "part.dtd">
+
+<part xmlns:xi="http://www.w3.org/2001/XInclude">
+ <header>
+ <copyright>
+ <year>1996</year><year>2017</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 User's Guide</title>
+ <prepared>OTP Team</prepared>
+ <docno></docno>
+ <date>2017-12-01</date>
+ <rev>0.1</rev>
+ <file>part.xml</file>
+ </header>
+ <description>
+ <p>The System Architecture Support Libraries SASL application
+ provides support for alarm handling, release handling, and
+ related functions.</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..7f4d5b384f 100644
--- a/lib/kernel/doc/src/ref_man.xml
+++ b/lib/kernel/doc/src/ref_man.xml
@@ -52,6 +52,10 @@
<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="net_adm.xml"/>
<xi:include href="net_kernel.xml"/>
<xi:include href="os.xml"/>
diff --git a/lib/kernel/doc/src/specs.xml b/lib/kernel/doc/src/specs.xml
index 29d52f23bb..a67e26ef16 100644
--- a/lib/kernel/doc/src/specs.xml
+++ b/lib/kernel/doc/src/specs.xml
@@ -20,6 +20,10 @@
<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_net_adm.xml"/>
<xi:include href="../specs/specs_net_kernel.xml"/>
<xi:include href="../specs/specs_os.xml"/>