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authorSiri Hansen <[email protected]>2018-05-08 14:36:37 +0200
committerSiri Hansen <[email protected]>2018-05-09 10:10:24 +0200
commit6f49591e7d5bf11d8bfc6014a0711ae59e3f3c33 (patch)
tree71d60985deedf8b8936c088ba745269d6ee7378c /lib/kernel/doc/src
parentbf0e9a16660a560db7c3e13d8021a4b7e87cfb27 (diff)
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Update reference manuals for logger
Diffstat (limited to 'lib/kernel/doc/src')
-rw-r--r--lib/kernel/doc/src/logger.xml371
-rw-r--r--lib/kernel/doc/src/logger_filters.xml14
-rw-r--r--lib/kernel/doc/src/logger_formatter.xml213
3 files changed, 455 insertions, 143 deletions
diff --git a/lib/kernel/doc/src/logger.xml b/lib/kernel/doc/src/logger.xml
index 2f7feb5eef..d901454e62 100644
--- a/lib/kernel/doc/src/logger.xml
+++ b/lib/kernel/doc/src/logger.xml
@@ -67,37 +67,86 @@
<datatype>
<name name="metadata"/>
<desc>
- <p>Metadata associated with the message to be logged.</p>
+ <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:monotonic_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 overwrites process metadata, which in turn
+ overwrites values set by Logger.</p>
</desc>
</datatype>
<datatype>
<name name="config"/>
<desc>
- <p></p>
+ <p>Configuration data for the logger part of Logger, or for a handler.</p>
+ <p>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>
+ <item><c>formatter => {logger_formatter,DefaultFormatterConfig</c>}</item>
+ </list>
+ <p>See the <seealso marker="logger_formatter#configuration">
+ <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></p>
+ <p>A unique identifier for a handler instance.</p>
</desc>
</datatype>
<datatype>
<name name="filter_id"/>
<desc>
- <p></p>
+ <p>A unique identifier for a filter.</p>
</desc>
</datatype>
<datatype>
<name name="filter"/>
<desc>
- <p></p>
+ <p>A filter which can be installed for logger or for a handler.</p>
+ </desc>
+ </datatype>
+ <datatype>
+ <name name="filter_arg"/>
+ <desc>
+ <p>The second argument to the filter fun.</p>
</desc>
</datatype>
<datatype>
<name name="filter_return"/>
<desc>
- <p></p>
+ <p>The return value from the filter fun.</p>
+ </desc>
+ </datatype>
+ <datatype>
+ <name name="timestamp"/>
+ <desc>
+ <p>A timestamp produced
+ with <seealso marker="erts:erlang#monotonic_time-1">
+ <c>erlang:monotonic_time(microsecond)</c></seealso>.</p>
</desc>
</datatype>
</datatypes>
@@ -126,14 +175,10 @@
</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>
+ taken from the macro name, and location data is added. See the
+ description of
+ the <seealso marker="#type-metadata"><c>metadata()</c></seealso>
+ type for more information about the location data.</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
@@ -267,7 +312,7 @@
<func>
<name name="i" arity="0"/>
- <fsummary>Get information about all logger configurations</fsummary>
+ <fsummary>Get all logger configurations</fsummary>
<desc>
<p>Same as <seealso marker="#i/1"><c>logger:i(term)</c></seealso></p>
</desc>
@@ -277,26 +322,29 @@
<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>
+ <fsummary>Get 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>
+ <p>Display or return all current logger configuration.</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">
+ <tag><c><anno>Action</anno> = string</c></tag>
+ <item>
+ <p>Return the pretty printed current logger configuration
+ as iodata.</p>
+ </item>
+ <tag><c><anno>Action</anno> = term</c></tag>
+ <item>
+ <p>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">
+ 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:
+ The same as calling <c>logger:i()</c>.</p>
+ </item>
+ <tag><c><anno>Action</anno> = print</c></tag>
+ <item>
+ <p>Pretty print all the current logger configuration to
+ standard out. Example:</p>
<code><![CDATA[1> logger:i(print).
Current logger configuration:
Level: info
@@ -339,6 +387,39 @@ Current logger configuration:
<fsummary>Add a filter to the logger.</fsummary>
<desc>
<p>Add a filter to the 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()</c></tag>
+ <item>
+ <p>The filter <em>passed</em>. The next logger filter, if
+ any, is applied. If no more logger filters exist, the
+ log event is forwarded to the handler part of the
+ 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
+ logger filter, if any, is applied. If no more logger
+ filters exist, the value of the <c>filter_default</c>
+ configuration parameter for the logger specifies if the
+ log event shall be discarded or forwarded to the handler
+ part.</p>
+ </item>
+ </taglist>
+ <p>See section <seealso marker="logger_chapter#Filter">
+ Filter</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>
@@ -347,6 +428,39 @@ Current logger configuration:
<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()</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#Filter">Filter</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>
@@ -354,7 +468,8 @@ Current logger configuration:
<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>
+ <p>Remove the filter identified
+ by <c><anno>FilterId</anno></c> from the logger.</p>
</desc>
</func>
@@ -362,7 +477,9 @@ Current logger configuration:
<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>
+ <p>Remove the filter identified
+ by <c><anno>FilterId</anno></c> from the handler identified
+ by <c><anno>HandlerId</anno></c>.</p>
</desc>
</func>
@@ -371,6 +488,9 @@ Current logger configuration:
<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 reffering to this
+ handler.</p>
</desc>
</func>
@@ -378,7 +498,7 @@ Current logger configuration:
<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>
+ <p>Remove the handler identified by <c><anno>HandlerId</anno></c>.</p>
</desc>
</func>
@@ -386,10 +506,37 @@ Current logger configuration:
<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>
+ <p>Set the log level for the
+ specified <c><anno>Module</anno></c>.</p>
+ <p>The log level for a module overrides the global log level
+ of the logger for log event 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 global log level for the
+ 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 global log level.</p>
+ <p>If the level for <c>mymodule</c> is set 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 global log level for the logger, use
+ <seealso marker="#set_logger_config/2">
+ <c>logger:set_logger_config(level,Level)</c></seealso>.</p>
+ <p>To change the log level for a handler, use
+ <seealso marker="#set_handler_config/3">
+ <c>logger:set_handler_config(HandlerId,level,Level)</c></seealso>.</p>
+ <note>
+ <p>The originating module for a log event is only detected
+ if <c>mfa=>{Module,Function,Arity}</c> exists in the
+ metadata. When log macros are used, this association is
+ automatically added to all log events. If the logger API
+ is called directly, without using a macro, the logging
+ client must explicitly add this information.</p>
+ </note>
</desc>
</func>
@@ -414,6 +561,8 @@ Current logger configuration:
with <seealso marker="#get_logger_config-0"><c>get_logger_config/0</c>
</seealso>, then merge in your added or updated
associations before writing it back.</p>
+ <p>If a key is removed compared to the current configuration,
+ the default value is used.</p>
</desc>
</func>
@@ -423,7 +572,7 @@ Current logger configuration:
<desc>
<p>Add or update configuration data for the logger. If the
given <c><anno>Key</anno></c> already exists, its associated
- value will be set to <c><anno>Value</anno></c>. If it
+ value will be changed to <c><anno>Value</anno></c>. If it
doesn't exist, it will be added.</p>
</desc>
</func>
@@ -440,6 +589,11 @@ Current logger configuration:
with <seealso marker="#get_handler_config-1"><c>get_handler_config/1</c>
</seealso>, then merge in your added or updated
associations before writing it back.</p>
+ <p>If a key is removed compared to the current configuration,
+ and the key is know 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>
@@ -449,10 +603,10 @@ Current logger configuration:
handler.</fsummary>
<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 set to <c><anno>Value</anno></c>. If it
- doesn't exist, it will be added.</p>
+ handler. If the given <c><anno>Key</anno></c> already
+ exists, its associated value will be changed
+ to <c><anno>Value</anno></c>. If it doesn't exist, it will
+ be added.</p>
</desc>
</func>
@@ -471,30 +625,36 @@ Current logger configuration:
<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 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>
+ <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="update_process_metadata" arity="1"/>
- <fsummary>Update metadata to use when logging from current process.</fsummary>
+ <fsummary>Set or update metadata to use when logging from
+ current process.</fsummary>
<desc>
- <p>Update metadata to use when logging from current process</p>
- <p>This function behaves as if it was implemented as follows:</p>
+ <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 marker="#set_process_metadata-1">
+ <c>set_process_metadata/1</c>
</seealso>.</p>
</desc>
</func>
@@ -505,7 +665,9 @@ logger:set_process_metadata(maps:merge(logger:get_process_metadata(),Meta))
<desc>
<p>Retrieve data set
with <seealso marker="#set_process_metadata-1">
- <c>set_process_metadata/1</c></seealso>.</p>
+ <c>set_process_metadata/1</c></seealso> or
+ <seealso marker="#update_process_metadata-1">
+ <c>update_process_metadata/1</c></seealso>.</p>
</desc>
</func>
@@ -515,12 +677,103 @@ logger:set_process_metadata(maps:merge(logger:get_process_metadata(),Meta))
<desc>
<p>Delete data set
with <seealso marker="#set_process_metadata-1">
- <c>set_process_metadata/1</c></seealso>.</p>
+ <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="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>.</p>
+ <p>This is the default report callback used
+ by <seealso marker="logger_formatter">
+ <c>logger_formatter</c></seealso> when no custom report
+ callback is found.</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 the <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>
+ <title>Callback Functions</title>
+ <p>The following functions are to be exported from a handler
+ callback module.</p>
+ </section>
+
+ <funcs>
+ <func>
+ <name>Module:adding_handler(HandlerId,Config1) -> {ok,Config2} | {error,Reason}</name>
+ <fsummary>An instance of this handler is about to be added.</fsummary>
+ <type>
+ <v>HandlerId =
+ <seealso marker="#type-handler_id">handler_id()</seealso></v>
+ <v>Config1 = Config2 =
+ <seealso marker="#type-config">config()</seealso></v>
+ <v>Reason = term()</v>
+ </type>
+ <desc>
+ <p>This callback function is optional.</p>
+ <p>The function is called when an new handler is about to be
+ added, and the purpose is to verify the configuration and
+ initiate all resourced needed by the handler.</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>Module:removing_handler(HandlerId,Config) -> ok</name>
+ <fsummary>The given handler is about to be removed.</fsummary>
+ <type>
+ <v>HandlerId =
+ <seealso marker="#type-handler_id">handler_id()</seealso></v>
+ <v>Config =
+ <seealso marker="#type-config">config()</seealso></v>
+ </type>
+ <desc>
+ <p>This callback function is optional.</p>
+ <p>The function is called when a handler is about to be
+ removed, and the purpose is to release all resources used by
+ the handler. The return value is ignored by Logger.</p>
+ </desc>
+ </func>
+
+ <func>
+ <name>Module:changing_config(HandlerId,Config1,Config2) -> {ok,Config3} | {error,Reason}</name>
+ <fsummary>The configuration for this handler is about to change.</fsummary>
+ <type>
+ <v>HandlerId =
+ <seealso marker="#type-handler_id">handler_id()</seealso></v>
+ <v>Config1 = Config2 = Config3 =
+ <seealso marker="#type-config">config()</seealso></v>
+ <v>Reason = term()</v>
+ </type>
+ <desc>
+ <p>This callback function is optional.</p>
+ <p>The function is called when the configuration for a handler
+ is about to change, and 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>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>
+ </funcs>
</erlref>
diff --git a/lib/kernel/doc/src/logger_filters.xml b/lib/kernel/doc/src/logger_filters.xml
index d742391e35..c34ec7d14c 100644
--- a/lib/kernel/doc/src/logger_filters.xml
+++ b/lib/kernel/doc/src/logger_filters.xml
@@ -33,16 +33,20 @@
<file>logger_filters.xml</file>
</header>
<module>logger_filters</module>
- <modulesummary>Filters to use with logger.</modulesummary>
+ <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
+ <p>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>
+ <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_logger_filter-1">
+ <c>logger:remove_logger_filter/1</c></seealso>
+ and <seealso marker="logger#remove_handler_filter-2">
+ <c>logger:remove_handler_filter/2</c></seealso>.</p>
</description>
<funcs>
diff --git a/lib/kernel/doc/src/logger_formatter.xml b/lib/kernel/doc/src/logger_formatter.xml
index a0940100ee..7df4c88f40 100644
--- a/lib/kernel/doc/src/logger_formatter.xml
+++ b/lib/kernel/doc/src/logger_formatter.xml
@@ -33,43 +33,38 @@
<file>logger_formatter.xml</file>
</header>
<module>logger_formatter</module>
- <modulesummary>Default formatter for the Logger application.</modulesummary>
+ <modulesummary>Default formatter for Logger.</modulesummary>
<description>
- <p>Default formatter for the Logger application.</p>
-
+ <p>Each log 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
+ (<c>unicode:chardata()</c>) which can be written to the output
+ device of the handler.</p>
+ <p><c>logger_formatter</c> is the default formatter used by
+ Logger.</p>
</description>
<section>
<title>Configuration</title>
- <p>The following configuration parameters can be set
- for <c>logger_formatter</c>:</p>
+ <p>The configuration term for <c>logger_formatter</c> is a map,
+ and the following keys can be set as configuration
+ parameters:</p>
<taglist>
- <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 whitespaces following
- directly after newlines are removed. Note that newlines
- added by the formatter template are not replaced.</p>
- <p>Default is <c>true</c>.</p>
- </item>
- <tag><c>legacy_header = boolen()</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 <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. See <seealso marker="#default_templates">Default
- Templates</seealso> for more information</p>
- <p>Default is <c>false</c>.</p>
- </item>
- <tag><c>report_cb = fun((logger:report()) -> {io:format(),[term()]})</c></tag>
+ <tag><c>chars_limit = pos_integer() | unlimited</c></tag>
<item>
- <p>A function with arity 1,
- returning <c>{Format,Args}</c>. This function will replace
- any <c>report_cb</c> found in metadata.</p>
+ <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">io_lib:format/3</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>Default is <c>unlimited</c>.</p>
+ <note>
+ <p><c>chars_limit</c> has no effect on log messages on
+ string form. These are expected to be short, but can still
+ be truncated by the <c>max_size</c> parameter.</p>
+ </note>
</item>
<tag><c>depth = pos_integer() | unlimited</c></tag>
<item>
@@ -82,47 +77,79 @@
<seealso marker="stdlib:io#format-2">io:format/2,3</seealso>
in STDLIB.</p>
<p>Default is <c>unlimited</c>.</p>
- </item>
- <tag><c>chars_limit = pos_integer() | 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">io_lib:format/3</seealso>.
- This value limits the total number of characters printed
- for each log event. Note that this is a soft limit. For a
- hard truncation limit, see option <c>max_size</c>.</p>
- <p>Default is <c>unlimited</c>.</p>
+ <note>
+ <p><c>depth</c> has no effect on log messages on string
+ form. These are expected to be short, but can still be
+ truncated by the <c>max_size</c> parameter.</p>
+ </note>
</item>
<tag><c>max_size = pos_integer() | unlimited</c></tag>
<item>
- <p>A positive integer representing the absolute maximum size
- a string returned from this formatter can have. If the
+ <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>depth</c> and/or <c>chars_limit</c>, it will be
- truncated.</p>
+ by <c>chars_limit</c> or <c>depth</c>, it is truncated.</p>
<p>Default is <c>unlimited</c>.</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 whitespaces following
+ directly after newlines are removed. Note that newlines
+ added by the <c>template</c> parameter are not replaced.</p>
+ <p>Default is <c>true</c>.</p>
+ </item>
+ <tag><c>legacy_header = boolen()</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 <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. See
+ section <seealso marker="#default_templates">Default
+ Templates</seealso> for more information.</p>
+ <p>Default is <c>false</c>.</p>
+ </item>
+ <tag><c>report_cb = fun((</c><seealso marker="logger#type-report"><c>logger:report()</c></seealso><c>) -> {</c><seealso marker="stdlib:io#type-format"><c>io:format()</c></seealso><c>,[term()]})</c></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 exist 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>
+ <p>The value must be a function with arity 1,
+ returning <c>{Format,Args}</c>, and it will be called with a
+ report as only argument.</p>
+ </item>
<tag><c>template = </c><seealso marker="#type-template"><c>template()</c></seealso></tag>
<item>
<p>The template is a list of atoms, tuples and strings. The
atoms <c>level</c> or <c>msg</c>, are treated as
placeholders for the severity level and the log message,
repectively. Other atoms or tuples are interpreted as
- placeholders for metadata, where atoms are expected to
- match top level keys, and tuples represent paths to sub
- keys in a nested map. For example the
- tuple <c>{key1,key2}</c> will be replaced by the value of
+ placeholders for metadata, where atoms are expected to match
+ top level keys, and tuples represent paths to sub keys when
+ the metadata is a nested map. For example the
+ tuple <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 would be replaced by the
- complete value of the <c>key1</c> field. The values are
- converted to strings.</p>
+ 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>Strings are printed literally.</p>
+ <p>Strings in the template are printed literally.</p>
<p>The default template differs depending on the values
of <c>legacy_header</c>
and <c>single_line</c>. See <seealso marker="#default_templates">Default
@@ -131,7 +158,8 @@
<tag><c>utc = boolean()</c></tag>
<item>
<p>If set to <c>true</c>, all dates are displayed in Universal
- Coordinated Time. Default is <c>false</c>.</p>
+ Coordinated Time.</p>
+ <p>Default is <c>false</c>.</p>
</item>
</taglist>
</section>
@@ -139,38 +167,51 @@
<section>
<marker id="default_templates"/>
<title>Default templates</title>
- <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>The default value for the <c>template</c> configuration
+ parameter depends on the value of <c>single_line</c>
+ and <c>legacy_header</c> as follows.</p>
- <p>which will cause log entries like this:</p>
+ <p>The log event used in the examples is:</p>
+ <code>
+?LOG_ERROR("name: ~p~nexit_reason: ~p",[my_reg_name,"It crashed"])</code>
- <code>2017-12-29 13:31:49.640317 error: process: &lt;0.74.0&gt;, exit_reason: "Something went wrong"</code>
+ <taglist>
+ <tag><c>legacy_header=true</c></tag>
+ <item>
+ <p>Default template: <c>[{logger_formatter,header},"\n",msg,"\n"]</c></p>
+
+ <p>Example log entry:</p>
+ <code>
+=ERROR REPORT==== 29-Dec-2017::13:30:51.245123 ===
+name: my_reg_name
+exit_reason: "It crashed"</code>
+
+ <p>Notice that all eight levels might occur in the heading,
+ not only <c>ERROR</c>, <c>WARNING</c> or <c>INFO</c> as the
+ old <c>error_logger</c> produced. And microseconds are
+ added at the end of the timestamp.</p>
+ </item>
- <p>The default template when both <c>legacy_header</c> and
- <c>single_line</c> are set to false is:</p>
+ <tag><c>single_line=true</c></tag>
+ <item>
+ <p>Default template: <c>[time," ",level,": ",msg,"\n"]</c></p>
- <code>[time," ",level,":\n",msg,"\n"]</code>
+ <p>Example log entry:</p>
+ <code>2017-12-29 13:31:49.640317 error: name: my_reg_name, exit_reason: "It crashed"</code>
+ </item>
- <p>which will cause log entries like this:</p>
+ <tag><c>legacy_header=false, single_line=false</c></tag>
+ <item>
+ <p>Default template: <c>[time," ",level,":\n",msg,"\n"]</c></p>
- <code>2017-12-29 13:32:25.191925 error:
- process: &lt;0.74.0&gt;
- exit_reason: "Something went wrong"</code>
+ <p>Example log entry:</p>
+ <code>
+2017-12-29 13:32:25.191925 error:
+name: my_reg_name
+exit_reason: "It crashed"</code>
+ </item>
+ </taglist>
</section>
<datatypes>
@@ -186,8 +227,22 @@
<name name="format" arity="2"/>
<fsummary>Formats the given message.</fsummary>
<desc>
- <p>This the callback function to be called from handlers. It
- formats the given messages.</p>
+ <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.</item>
+ <item>The size is limited according to the values of
+ configuration parameters <c>chars_limit</c>
+ and <c>depth</c>. Notice that this does not apply to
+ messages on string form.</item>
+ <item>The full log entry is composed according to
+ the <c>template</c>.</item>
+ <item>If the final string is too long, it is truncated
+ according to the value of configuration
+ parameter <c>max_size</c>.</item>
+ </list>
</desc>
</func>