diff options
Diffstat (limited to 'lib/kernel/doc/src/logger.xml')
| -rw-r--r-- | lib/kernel/doc/src/logger.xml | 157 |
1 files changed, 140 insertions, 17 deletions
diff --git a/lib/kernel/doc/src/logger.xml b/lib/kernel/doc/src/logger.xml index d901454e62..183102f240 100644 --- a/lib/kernel/doc/src/logger.xml +++ b/lib/kernel/doc/src/logger.xml @@ -33,10 +33,49 @@ <file>logger.xml</file> </header> <module>logger</module> - <modulesummary>API module for the logger application.</modulesummary> + <modulesummary>API module for the logger.</modulesummary> <description> - + <p> + This module is the main logger API. It contains functions that allow + application to use a single log API and the system to manage those log + events independently. To log events the logger + <seealso marker="#macros">macros</seealso> should be used. For instance, + to log a new error log event:</p> + <code> +?LOG_ERROR("error happened because: ~p",[Reason]). %% With macro +logger:error("error happened because: ~p",[Reason]). %% Without macro + </code> + <p>This log event will then be sent to the configured log handlers which + by default means that it will be printed to the console. If you want + your systems logs to be printed to a file instead of the console you + have to configure the default handler to do so. The simplest way is + to include the following in your <seealso marker="config"><c>sys.config</c></seealso>.</p> + <code> +[{kernel, + [{logger, + [{handler,default,logger_std_h, + #{logger_std_h=>#{type=>{file,"path/to/file.log"}}}}]}]}]. + </code> + <p> + For more information about: + </p> + <list type="bulleted"> + <item>how to use the API, + see <seealso marker="logger_chapter">the User's Guide</seealso>.</item> + <item>how to configure logger, + see the <seealso marker="logger_chapter#configuration">Configuration</seealso> + section in the User's Guide.</item> + <item>the convinience macros in logger.hrl, + see <seealso marker="#macros">the macro section</seealso>.</item> + <item>what the builtin formatter can do, + see <seealso marker="logger_formatter">logger_formatter</seealso>.</item> + <item>what the builtin handlers can do, + see <seealso marker="logger_std_h">logger_std_h</seealso> and + <seealso marker="logger_disk_log_h">logger_disk_log_h</seealso>.</item> + <item>what builtin filters are available, + see <seealso marker="logger_filters">logger_filters</seealso>.</item> + </list> </description> <datatypes> @@ -348,16 +387,16 @@ <code><![CDATA[1> logger:i(print). Current logger configuration: Level: info - FilterDefault: log + Filter Default: log Filters: Handlers: - Id: logger_std_h + Id: default Module: logger_std_h Level: info Formatter: Module: logger_formatter - Config: #{template => [{logger_formatter,header},"\n",msg,"\n"], - legacy_header => true} + Config: #{legacy_header => true,single_line => false, + template => [{logger_formatter,header},"\n",msg,"\n"]} Filter Default: stop Filters: Id: stop_progress @@ -550,17 +589,68 @@ Current logger configuration: </func> <func> + <name name="add_handlers" arity="1" clause_i="1"/> + <fsummary>Setup logger handlers from the applications configuration parameters.</fsummary> + <desc> + <p>Reads the application configuration parameter <c>logger</c> and + calls <c>logger:add_handlers/1</c> with it contents.</p> + </desc> + </func> + + <func> + <name name="add_handlers" arity="1" clause_i="2"/> + <fsummary>Setup logger handlers.</fsummary> + <type name="config_handler"/> + <desc> + <p>This function should be used by custom logger handlers to make + configuration consistent no matter which handler the system uses. + Normal usage to to add a call to <c>logger:add_handlers/1</c> + just after the processes that the handler needs are started + and pass the applications logger config as an argument. Eg.</p> + <code> +-behaviour(application). +start(_, []) -> + case supervisor:start_link({local, my_sup}, my_sup, []) of + {ok, Pid} -> + ok = logger:add_handlers(my_app), + {ok, Pid, []}; + Error -> Error + end.</code> + <p>This will read the <c>logger</c> configuration parameter from + the handler application and start the configured handlers. The contents + of the configuration use the same rules as the + <seealso marker="logger_chapter#handler-configuration">logger handler configuration</seealso>. + </p> + <p>If the handler is meant to replace the default handler the kernels + default handlers have to be disabled before the new handler is added. + A <c>sys.config</c> file that disables the kernel handler and adds + a custom handler could looks like this:</p> + <code> +[{kernel, + [{logger, + %% Disable the default kernel handler + [{handler,default,undefined}]}]}, + {my_app, + [{logger, + %% Enable this handler as the default + [{handler,default,my_handler,#{}}]}]}]. + </code> + </desc> + </func> + + <func> <name name="set_logger_config" arity="1"/> <fsummary>Set configuration data for the logger.</fsummary> <desc> <p>Set configuration data for the logger. This overwrites the current logger configuration.</p> <p>To modify the existing configuration, - use <seealso marker="#set_logger_config-2"><c>set_logger_config/2</c> - </seealso>, or read the current configuration + use <seealso marker="#update_logger_config-1"> + <c>update_logger_config/1</c></seealso>, or, if a more + complex merge is needed, read the current 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> + </seealso>, then do the merge before writing the new + configuration back with this function.</p> <p>If a key is removed compared to the current configuration, the default value is used.</p> </desc> @@ -573,7 +663,23 @@ Current logger configuration: <p>Add or update configuration data for the logger. 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> + does not exist, it will be added.</p> + </desc> + </func> + + <func> + <name name="update_logger_config" arity="1"/> + <fsummary>Update configuration data for the logger.</fsummary> + <desc> + <p>Update configuration data for the logger. This function + behaves as if it was implemented as follows:</p> + <code type="erl"> +{ok,Old} = logger:get_logger_config(), +logger:set_logger_config(maps:merge(Old,Config)). + </code> + <p>To overwrite the existing configuration without any merge, + use <seealso marker="#set_logger_config-1"><c>set_logger_config/1</c> + </seealso>.</p> </desc> </func> @@ -584,11 +690,12 @@ Current logger configuration: <p>Set configuration data for the specified handler. This overwrites the current handler configuration.</p> <p>To modify the existing configuration, - use <seealso marker="#set_handler_config-3"><c>set_handler_config/3</c> - </seealso>, or read the current configuration + use <seealso marker="#update_handler_config-2"> + <c>update_handler_config/2</c></seealso>, or, if a more + complex merge is needed, read the current configuration with <seealso marker="#get_handler_config-1"><c>get_handler_config/1</c> - </seealso>, then merge in your added or updated - associations before writing it back.</p> + </seealso>, then do the merge before writing the new + configuration back with this function.</p> <p>If a key is removed compared to the current configuration, and the key is know by Logger, the default value is used. If it is a custom key, then it is up to the handler @@ -605,12 +712,28 @@ Current logger configuration: <p>Add or update configuration data for the specified handler. If the given <c><anno>Key</anno></c> already exists, its associated value will be changed - to <c><anno>Value</anno></c>. If it doesn't exist, it will + to <c><anno>Value</anno></c>. If it does not exist, it will be added.</p> </desc> </func> <func> + <name name="update_handler_config" arity="2"/> + <fsummary>Update configuration data for the specified handler.</fsummary> + <desc> + <p>Update configuration data for the specified handler. This function + behaves as if it was implemented as follows:</p> + <code type="erl"> +{ok,{_,Old}} = logger:get_handler_config(HandlerId), +logger:set_handler_config(HandlerId,maps:merge(Old,Config)). + </code> + <p>To overwrite the existing configuration without any merge, + use <seealso marker="#set_handler_config-2"><c>set_handler_config/2</c> + </seealso>.</p> + </desc> + </func> + + <func> <name name="compare_levels" arity="2"/> <fsummary>Compare the severity of two log levels.</fsummary> <desc> @@ -650,7 +773,7 @@ Current logger configuration: <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)) +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"> |