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Diffstat (limited to 'lib/kernel/doc/src/error_logger.xml')
| -rw-r--r-- | lib/kernel/doc/src/error_logger.xml | 371 |
1 files changed, 227 insertions, 144 deletions
diff --git a/lib/kernel/doc/src/error_logger.xml b/lib/kernel/doc/src/error_logger.xml index 91bf57cb91..c170b4fa34 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> @@ -28,39 +28,40 @@ <date></date> <rev></rev> </header> - <module>error_logger</module> + <module since="">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 @@ -75,8 +76,8 @@ </datatypes> <funcs> <func> - <name name="add_report_handler" arity="1"/> - <name name="add_report_handler" arity="2"/> + <name name="add_report_handler" arity="1" since=""/> + <name name="add_report_handler" arity="2" since=""/> <fsummary>Add an event handler to the error logger.</fsummary> <desc> <p>Adds a new event handler to the error logger. The event @@ -89,167 +90,213 @@ 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> - <name name="delete_report_handler" arity="1"/> + <name name="delete_report_handler" arity="1" since=""/> <fsummary>Delete an event handler from the error logger.</fsummary> <desc> <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> + <name name="error_msg" arity="1" since=""/> + <name name="error_msg" arity="2" since=""/> + <name name="format" arity="2" since=""/> + <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> </desc> </func> <func> - <name name="error_report" arity="1"/> - <fsummary>Send a standard error report event to the error logger.</fsummary> + <name name="error_report" arity="1" since=""/> + <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> + <name name="error_report" arity="2" since=""/> + <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> - <name name="get_format_depth" arity="0"/> + <name name="get_format_depth" arity="0" since="OTP 20.0"/> <fsummary>Get the value of the Kernel application variable <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> + <name name="info_msg" arity="1" since=""/> + <name name="info_msg" arity="2" since=""/> + <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> </desc> </func> <func> - <name name="info_report" arity="1"/> - <fsummary>Send a standard information report event to the error logger.</fsummary> + <name name="info_report" arity="1" since=""/> + <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> + <name name="info_report" arity="2" since=""/> + <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> - <name name="logfile" arity="1" clause_i="1"/> - <name name="logfile" arity="1" clause_i="2"/> - <name name="logfile" arity="1" clause_i="3"/> + <name name="logfile" arity="1" clause_i="1" since=""/> + <name name="logfile" arity="1" clause_i="2" since=""/> + <name name="logfile" arity="1" clause_i="3" since=""/> <fsummary>Enable or disable error printouts to a file.</fsummary> <type variable="Filename"/> <type variable="OpenReason" name_i="1"/> @@ -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> @@ -291,19 +346,24 @@ ok</pre> </desc> </func> <func> - <name name="tty" arity="1"/> + <name name="tty" arity="1" since=""/> <fsummary>Enable or disable printouts to the terminal.</fsummary> <desc> <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> - <name name="warning_map" arity="0"/> + <name name="warning_map" arity="0" since=""/> <fsummary>Return the current mapping for warning events.</fsummary> <desc> <p>Returns the current mapping for warning events. Events sent @@ -340,51 +400,73 @@ ok</pre> </desc> </func> <func> - <name name="warning_msg" arity="1"/> - <name name="warning_msg" arity="2"/> - <fsummary>Send a standard warning event to the error logger.</fsummary> + <name name="warning_msg" arity="1" since=""/> + <name name="warning_msg" arity="2" since=""/> + <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> </desc> </func> <func> - <name name="warning_report" arity="1"/> - <fsummary>Send a standard warning report event to the error logger.</fsummary> + <name name="warning_report" arity="1" since=""/> + <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> + <name name="warning_report" arity="2" since=""/> + <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> |