1<?xml version="1.0" encoding="utf-8" ?> 2<!DOCTYPE erlref SYSTEM "erlref.dtd"> 3 4<erlref> 5 <header> 6 <copyright> 7 <year>2017</year><year>2020</year> 8 <holder>Ericsson AB. All Rights Reserved.</holder> 9 </copyright> 10 <legalnotice> 11 Licensed under the Apache License, Version 2.0 (the "License"); 12 you may not use this file except in compliance with the License. 13 You may obtain a copy of the License at 14 15 http://www.apache.org/licenses/LICENSE-2.0 16 17 Unless required by applicable law or agreed to in writing, software 18 distributed under the License is distributed on an "AS IS" BASIS, 19 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 20 See the License for the specific language governing permissions and 21 limitations under the License. 22 23 </legalnotice> 24 25 <title>logger</title> 26 <prepared></prepared> 27 <responsible></responsible> 28 <docno></docno> 29 <approved></approved> 30 <checked></checked> 31 <date></date> 32 <rev>A</rev> 33 <file>logger.xml</file> 34 </header> 35 <module since="OTP 21.0">logger</module> 36 <modulesummary>API module for Logger, the standard logging facility 37 in Erlang/OTP.</modulesummary> 38 39 <description> 40 <p>This module implements the main API for logging in 41 Erlang/OTP. To create a log event, use the 42 <seealso marker="#logging_API">API functions</seealso> or the 43 log 44 <seealso marker="#macros">macros</seealso>, for example:</p> 45 <code> 46?LOG_ERROR("error happened because: ~p", [Reason]). % With macro 47logger:error("error happened because: ~p", [Reason]). % Without macro 48 </code> 49 <p>To configure the Logger backend, 50 use <seealso marker="kernel_app#logger">Kernel configuration 51 parameters</seealso> 52 or <seealso marker="#configuration_API">configuration 53 functions</seealso> in the Logger API.</p> 54 55 <p>By default, the Kernel application installs one log handler at 56 system start. This handler is named <c>default</c>. It receives 57 and processes standard log events produced by the Erlang runtime 58 system, standard behaviours and different Erlang/OTP 59 applications. The log events are by default printed to the 60 terminal.</p> 61 <p>If you want your systems logs to be printed to a file instead, 62 you must configure the default handler to do so. The simplest 63 way is to include the following in 64 your <seealso marker="config"><c>sys.config</c></seealso>:</p> 65 <code> 66[{kernel, 67 [{logger, 68 [{handler, default, logger_std_h, 69 #{config => #{file => "path/to/file.log"}}}]}]}]. 70 </code> 71 <p> 72 For more information about: 73 </p> 74 <list type="bulleted"> 75 <item>the Logger facility in general, see 76 the <seealso marker="logger_chapter">User's 77 Guide</seealso>.</item> 78 <item>how to configure Logger, see 79 the <seealso marker="logger_chapter#configuration">Configuration</seealso> 80 section in the User's Guide.</item> 81 <item>the built-in handlers, 82 see <seealso marker="logger_std_h">logger_std_h</seealso> and 83 <seealso marker="logger_disk_log_h">logger_disk_log_h</seealso>.</item> 84 <item>the built-in formatter, 85 see <seealso marker="logger_formatter">logger_formatter</seealso>.</item> 86 <item>built-in filters, 87 see <seealso marker="logger_filters">logger_filters</seealso>.</item> 88 </list> 89 90 <note> 91 <p>Since Logger is new in Erlang/OTP 21.0, we do reserve the right 92 to introduce changes to the Logger API and functionality in 93 patches following this release. These changes might or might not 94 be backwards compatible with the initial version.</p> 95 </note> 96 97 </description> 98 99 <datatypes> 100 <datatype> 101 <name name="filter"/> 102 <desc> 103 <p>A filter which can be installed as a handler filter, or as 104 a primary filter in Logger.</p> 105 </desc> 106 </datatype> 107 <datatype> 108 <name name="filter_arg"/> 109 <desc> 110 <p>The second argument to the filter fun.</p> 111 </desc> 112 </datatype> 113 <datatype> 114 <name name="filter_id"/> 115 <desc> 116 <p>A unique identifier for a filter.</p> 117 </desc> 118 </datatype> 119 <datatype> 120 <name name="filter_return"/> 121 <desc> 122 <p>The return value from the filter fun.</p> 123 </desc> 124 </datatype> 125 <datatype> 126 <name name="formatter_config"/> 127 <desc> 128 <p>Configuration data for the 129 formatter. See <seealso marker="logger_formatter"> 130 <c>logger_formatter(3)</c></seealso> 131 for an example of a formatter implementation.</p> 132 </desc> 133 </datatype> 134 <datatype> 135 <name name="handler_config"/> 136 <desc> 137 <p>Handler configuration data for Logger. The following 138 default values apply:</p> 139 <list> 140 <item><c>level => all</c></item> 141 <item><c>filter_default => log</c></item> 142 <item><c>filters => []</c></item> 143 <item><c>formatter => {logger_formatter, DefaultFormatterConfig</c>}</item> 144 </list> 145 <p>In addition to these, the following fields are 146 automatically inserted by Logger, values taken from the 147 two first parameters 148 to <seealso marker="#add_handler-3"><c>add_handler/3</c></seealso>:</p> 149 <list> 150 <item><c>id => HandlerId</c></item> 151 <item><c>module => Module</c></item> 152 </list> 153 <p>These are read-only and cannot be changed in runtime.</p> 154 <p>Handler specific configuration data is inserted by the 155 handler callback itself, in a sub structure associated with 156 the field named <c>config</c>. See 157 the <seealso marker="logger_std_h"><c>logger_std_h(3)</c></seealso> 158 and <seealso marker="logger_disk_log_h"><c>logger_disk_log_h(3)</c></seealso> 159 manual pages for information about the specifc configuration 160 for these handlers.</p> 161 <p>See the <seealso marker="logger_formatter#type-config"> 162 <c>logger_formatter(3)</c></seealso> manual page for 163 information about the default configuration for this 164 formatter.</p> 165 </desc> 166 </datatype> 167 <datatype> 168 <name name="handler_id"/> 169 <desc> 170 <p>A unique identifier for a handler instance.</p> 171 </desc> 172 </datatype> 173 <datatype> 174 <name name="level"/> 175 <desc> 176 <p>The severity level for the message to be logged.</p> 177 </desc> 178 </datatype> 179 <datatype> 180 <name name="log_event"/> 181 <desc> 182 <p></p> 183 </desc> 184 </datatype> 185 <datatype> 186 <name name="metadata"/> 187 <desc> 188 <p>Metadata for the log event.</p> 189 <p>Logger adds the following metadata to each log event:</p> 190 <list> 191 <item><c>pid => self()</c></item> 192 <item><c>gl => group_leader()</c></item> 193 <item><c>time => logger:timestamp()</c></item> 194 </list> 195 <p>When a log macro is used, Logger also inserts location 196 information:</p> 197 <list> 198 <item><c>mfa => {?MODULE, ?FUNCTION_NAME, ?FUNCTION_ARITY}</c></item> 199 <item><c>file => ?FILE</c></item> 200 <item><c>line => ?LINE</c></item> 201 </list> 202 <p>You can add custom metadata, either by specifying a map as 203 the last parameter to any of the log macros or the API 204 functions, or by setting process metadata 205 with <seealso marker="#set_process_metadata-1"> 206 <c>set_process_metadata/1</c></seealso> 207 or <seealso marker="#update_process_metadata-1"> 208 <c>update_process_metadata/1</c></seealso>.</p> 209 <p>Logger merges all the metadata maps before forwarding the 210 log event to the handlers. If the same keys occur, values 211 from the log call overwrite process metadata, which in turn 212 overwrite values set by Logger.</p> 213 <p>The following custom metadata keys have special meaning:</p> 214 <taglist> 215 <tag><c>domain</c></tag> 216 <item> 217 <p>The value associated with this key is used by filters 218 for grouping log events originating from, for example, 219 specific functional 220 areas. See <seealso marker="logger_filters#domain-2"> 221 <c>logger_filters:domain/2</c></seealso> 222 for a description of how this field can be used.</p> 223 </item> 224 <tag><c>report_cb</c></tag> 225 <item> 226 <p>If the log message is specified as 227 a <seealso marker="#type-report"><c>report()</c></seealso>, 228 the <c>report_cb</c> key can be associated with a fun 229 (report callback) that converts the report to a format 230 string and arguments, or directly to a string. See the 231 type definition 232 of <seealso marker="#type-report_cb"><c>report_cb()</c></seealso>, 233 and 234 section <seealso marker="logger_chapter#log_message">Log 235 Message</seealso> in the User's Guide for more 236 information about report callbacks.</p> 237 </item> 238 </taglist> 239 </desc> 240 </datatype> 241 <datatype> 242 <name name="msg_fun"/> 243 <desc> 244 <p></p> 245 </desc> 246 </datatype> 247 <datatype> 248 <name name="olp_config"/> 249 <desc> 250 <p></p> 251 </desc> 252 </datatype> 253 <datatype> 254 <name name="primary_config"/> 255 <desc> 256 <p>Primary configuration data for Logger. The following 257 default values apply:</p> 258 <list> 259 <item><c>level => info</c></item> 260 <item><c>filter_default => log</c></item> 261 <item><c>filters => []</c></item> 262 </list> 263 </desc> 264 </datatype> 265 <datatype> 266 <name name="report"/> 267 <desc> 268 <p></p> 269 </desc> 270 </datatype> 271 <datatype> 272 <name name="report_cb"/> 273 <desc> 274 <p>A fun which converts a <seealso marker="#type-report"><c>report()</c> 275 </seealso> to a format string and arguments, or directly to a string. 276 See section <seealso marker="logger_chapter#log_message">Log 277 Message</seealso> in the User's Guide for more 278 information.</p> 279 </desc> 280 </datatype> 281 <datatype> 282 <name name="report_cb_config"/> 283 <desc> 284 <p></p> 285 </desc> 286 </datatype> 287 <datatype> 288 <name name="timestamp"/> 289 <desc> 290 <p>A timestamp produced 291 with <seealso marker="#timestamp-0"> 292 <c>logger:timestamp()</c></seealso>.</p> 293 </desc> 294 </datatype> 295 </datatypes> 296 297 <section> 298 <title>Macros</title> 299 <p>The following macros are defined in <c>logger.hrl</c>, which 300 is included in a module with the directive</p> 301 <code> 302 -include_lib("kernel/include/logger.hrl").</code> 303 304 <list> 305 <item><c>?LOG_EMERGENCY(StringOrReport[,Metadata])</c></item> 306 <item><c>?LOG_EMERGENCY(FunOrFormat,Args[,Metadata])</c></item> 307 <item><c>?LOG_ALERT(StringOrReport[,Metadata])</c></item> 308 <item><c>?LOG_ALERT(FunOrFormat,Args[,Metadata])</c></item> 309 <item><c>?LOG_CRITICAL(StringOrReport[,Metadata])</c></item> 310 <item><c>?LOG_CRITICAL(FunOrFormat,Args[,Metadata])</c></item> 311 <item><c>?LOG_ERROR(StringOrReport[,Metadata])</c></item> 312 <item><c>?LOG_ERROR(FunOrFormat,Args[,Metadata])</c></item> 313 <item><c>?LOG_WARNING(StringOrReport[,Metadata])</c></item> 314 <item><c>?LOG_WARNING(FunOrFormat,Args[,Metadata])</c></item> 315 <item><c>?LOG_NOTICE(StringOrReport[,Metadata])</c></item> 316 <item><c>?LOG_NOTICE(FunOrFormat,Args[,Metadata])</c></item> 317 <item><c>?LOG_INFO(StringOrReport[,Metadata])</c></item> 318 <item><c>?LOG_INFO(FunOrFormat,Args[,Metadata])</c></item> 319 <item><c>?LOG_DEBUG(StringOrReport[,Metadata])</c></item> 320 <item><c>?LOG_DEBUG(FunOrFormat,Args[,Metadata])</c></item> 321 <item><c>?LOG(Level,StringOrReport[,Metadata])</c></item> 322 <item><c>?LOG(Level,FunOrFormat,Args[,Metadata])</c></item> 323 </list> 324 325 <p>All macros expand to a call to Logger, where <c>Level</c> is 326 taken from the macro name, or from the first argument in the 327 case of the <c>?LOG</c> macro. Location data is added to the 328 metadata as described under 329 the <seealso marker="#type-metadata"><c>metadata()</c></seealso> 330 type definition.</p> 331 332 <p>The call is wrapped in a case statement and will be evaluated 333 only if <c>Level</c> is equal to or below the configured log 334 level.</p> 335 </section> 336 337 <section> 338 <marker id="logging_API"/> 339 <title>Logging API functions</title> 340 </section> 341 <funcs> 342 <func> 343 <name since="OTP 21.0">emergency(StringOrReport[,Metadata])</name> 344 <name since="OTP 21.0">emergency(Format,Args[,Metadata])</name> 345 <name since="OTP 21.0">emergency(Fun,FunArgs[,Metadata])</name> 346 <fsummary>Logs the given message as level <c>emergency</c>.</fsummary> 347 <desc> 348 <p>Equivalent to 349 <seealso marker="#log-2"><c>log(emergency,...)</c></seealso>.</p> 350 </desc> 351 </func> 352 353 <func> 354 <name since="OTP 21.0">alert(StringOrReport[,Metadata])</name> 355 <name since="OTP 21.0">alert(Format,Args[,Metadata])</name> 356 <name since="OTP 21.0">alert(Fun,FunArgs[,Metadata])</name> 357 <fsummary>Logs the given message as level <c>alert</c>.</fsummary> 358 <desc> 359 <p>Equivalent to 360 <seealso marker="#log-2"><c>log(alert,...)</c></seealso>.</p> 361 </desc> 362 </func> 363 364 <func> 365 <name since="OTP 21.0">critical(StringOrReport[,Metadata])</name> 366 <name since="OTP 21.0">critical(Format,Args[,Metadata])</name> 367 <name since="OTP 21.0">critical(Fun,FunArgs[,Metadata])</name> 368 <fsummary>Logs the given message as level <c>critical</c>.</fsummary> 369 <desc> 370 <p>Equivalent to 371 <seealso marker="#log-2"><c>log(critical,...)</c></seealso>.</p> 372 </desc> 373 </func> 374 375 <func> 376 <name since="OTP 21.0">error(StringOrReport[,Metadata])</name> 377 <name since="OTP 21.0">error(Format,Args[,Metadata])</name> 378 <name since="OTP 21.0">error(Fun,FunArgs[,Metadata])</name> 379 <fsummary>Logs the given message as level <c>error</c>.</fsummary> 380 <desc> 381 <p>Equivalent to 382 <seealso marker="#log-2"><c>log(error,...)</c></seealso>.</p> 383 </desc> 384 </func> 385 386 <func> 387 <name since="OTP 21.0">warning(StringOrReport[,Metadata])</name> 388 <name since="OTP 21.0">warning(Format,Args[,Metadata])</name> 389 <name since="OTP 21.0">warning(Fun,FunArgs[,Metadata])</name> 390 <fsummary>Logs the given message as level <c>warning</c>.</fsummary> 391 <desc> 392 <p>Equivalent to 393 <seealso marker="#log-2"><c>log(warning,...)</c></seealso>.</p> 394 </desc> 395 </func> 396 397 <func> 398 <name since="OTP 21.0">notice(StringOrReport[,Metadata])</name> 399 <name since="OTP 21.0">notice(Format,Args[,Metadata])</name> 400 <name since="OTP 21.0">notice(Fun,FunArgs[,Metadata])</name> 401 <fsummary>Logs the given message as level <c>notice</c>.</fsummary> 402 <desc> 403 <p>Equivalent to 404 <seealso marker="#log-2"><c>log(notice,...)</c></seealso>.</p> 405 </desc> 406 </func> 407 408 <func> 409 <name since="OTP 21.0">info(StringOrReport[,Metadata])</name> 410 <name since="OTP 21.0">info(Format,Args[,Metadata])</name> 411 <name since="OTP 21.0">info(Fun,FunArgs[,Metadata])</name> 412 <fsummary>Logs the given message as level <c>info</c>.</fsummary> 413 <desc> 414 <p>Equivalent to 415 <seealso marker="#log-2"><c>log(info,...)</c></seealso>.</p> 416 </desc> 417 </func> 418 419 <func> 420 <name since="OTP 21.0">debug(StringOrReport[,Metadata])</name> 421 <name since="OTP 21.0">debug(Format,Args[,Metadata])</name> 422 <name since="OTP 21.0">debug(Fun,FunArgs[,Metadata])</name> 423 <fsummary>Logs the given message as level <c>debug</c>.</fsummary> 424 <desc> 425 <p>Equivalent to 426 <seealso marker="#log-2"><c>log(debug,...)</c></seealso>.</p> 427 </desc> 428 </func> 429 430 <func> 431 <name name="log" arity="2" since="OTP 21.0"/> 432 <name name="log" arity="3" clause_i="1" since="OTP 21.0"/> 433 <name name="log" arity="3" clause_i="2" since="OTP 21.0"/> 434 <name name="log" arity="3" clause_i="3" since="OTP 21.0"/> 435 <name name="log" arity="4" clause_i="1" since="OTP 21.0"/> 436 <name name="log" arity="4" clause_i="2" since="OTP 21.0"/> 437 <fsummary>Logs the given message.</fsummary> 438 <type variable="Level"/> 439 <type variable="StringOrReport" name_i="1"/> 440 <type variable="Format" name_i="3"/> 441 <type variable="Args" name_i="3"/> 442 <type variable="Fun" name_i="4"/> 443 <type variable="FunArgs" name_i="4"/> 444 <type variable="Metadata"/> 445 <desc> 446 <p>Log the given message.</p> 447 </desc> 448 </func> 449 </funcs> 450 451 <section> 452 <marker id="configuration_API"/> 453 <title>Configuration API functions</title> 454 </section> 455 <funcs> 456 <func> 457 <name name="add_handler" arity="3" since="OTP 21.0"/> 458 <fsummary>Add a handler with the given configuration.</fsummary> 459 <desc> 460 <p>Add a handler with the given configuration.</p> 461 <p><c><anno>HandlerId</anno></c> is a unique identifier which 462 must be used in all subsequent calls referring to this 463 handler.</p> 464 </desc> 465 </func> 466 467 <func> 468 <name name="add_handler_filter" arity="3" since="OTP 21.0"/> 469 <fsummary>Add a filter to the specified handler.</fsummary> 470 <desc> 471 <p>Add a filter to the specified handler.</p> 472 <p>The filter fun is called with the log event as the first 473 parameter, and the specified <c>filter_args()</c> as the 474 second parameter.</p> 475 <p>The return value of the fun specifies if a log event is to 476 be discarded or forwarded to the handler callback:</p> 477 <taglist> 478 <tag><c>log_event()</c></tag> 479 <item> 480 <p>The filter <em>passed</em>. The next handler filter, if 481 any, is applied. If no more filters exist for this 482 handler, the log event is forwarded to the handler 483 callback.</p> 484 </item> 485 <tag><c>stop</c></tag> 486 <item> 487 <p>The filter <em>did not pass</em>, and the log event is 488 immediately discarded.</p> 489 </item> 490 <tag><c>ignore</c></tag> 491 <item> 492 <p>The filter has no knowledge of the log event. The next 493 handler filter, if any, is applied. If no more filters 494 exist for this handler, the value of 495 the <c>filter_default</c> configuration parameter for 496 the handler specifies if the log event shall be 497 discarded or forwarded to the handler callback.</p> 498 </item> 499 </taglist> 500 <p>See 501 section <seealso marker="logger_chapter#filters">Filters</seealso> 502 in the User's Guide for more information about filters.</p> 503 <p>Some built-in filters exist. These are defined in 504 <seealso marker="logger_filters"><c>logger_filters(3)</c></seealso>.</p> 505 </desc> 506 </func> 507 508 <func> 509 <name name="add_handlers" arity="1" clause_i="1" since="OTP 21.0"/> 510 <fsummary>Set up log handlers from the application's 511 configuration parameters.</fsummary> 512 <desc> 513 <p>Reads the application configuration parameter <c>logger</c> and 514 calls <c>add_handlers/1</c> with its contents.</p> 515 </desc> 516 </func> 517 518 <func> 519 <name name="add_handlers" arity="1" clause_i="2" since="OTP 21.0"/> 520 <fsummary>Setup logger handlers.</fsummary> 521 <type name="config_handler"/> 522 <desc> 523 <p>This function should be used by custom Logger handlers to make 524 configuration consistent no matter which handler the system uses. 525 Normal usage is to add a call to <c>logger:add_handlers/1</c> 526 just after the processes that the handler needs are started, 527 and pass the application's <c>logger</c> configuration as the argument. 528 For example:</p> 529 <code> 530-behaviour(application). 531start(_, []) -> 532 case supervisor:start_link({local, my_sup}, my_sup, []) of 533 {ok, Pid} -> 534 ok = logger:add_handlers(my_app), 535 {ok, Pid, []}; 536 Error -> Error 537 end.</code> 538 <p>This reads the <c>logger</c> configuration parameter from 539 the <c>my_app</c> application and starts the configured 540 handlers. The contents of the configuration use the same 541 rules as the 542 <seealso marker="logger_chapter#handler-configuration">logger handler configuration</seealso>. 543 </p> 544 <p>If the handler is meant to replace the default handler, the Kernel's 545 default handler have to be disabled before the new handler is added. 546 A <c>sys.config</c> file that disables the Kernel handler and adds 547 a custom handler could look like this:</p> 548 <code> 549[{kernel, 550 [{logger, 551 %% Disable the default Kernel handler 552 [{handler, default, undefined}]}]}, 553 {my_app, 554 [{logger, 555 %% Enable this handler as the default 556 [{handler, default, my_handler, #{}}]}]}]. 557 </code> 558 </desc> 559 </func> 560 561 <func> 562 <name name="add_primary_filter" arity="2" since="OTP 21.0"/> 563 <fsummary>Add a primary filter to Logger.</fsummary> 564 <desc> 565 <p>Add a primary filter to Logger.</p> 566 <p>The filter fun is called with the log event as the first 567 parameter, and the specified <c>filter_args()</c> as the 568 second parameter.</p> 569 <p>The return value of the fun specifies if a log event is to 570 be discarded or forwarded to the handlers:</p> 571 <taglist> 572 <tag><c>log_event()</c></tag> 573 <item> 574 <p>The filter <em>passed</em>. The next primary filter, if 575 any, is applied. If no more primary filters exist, the 576 log event is forwarded to the handler part of Logger, 577 where handler filters are applied.</p> 578 </item> 579 <tag><c>stop</c></tag> 580 <item> 581 <p>The filter <em>did not pass</em>, and the log event is 582 immediately discarded.</p> 583 </item> 584 <tag><c>ignore</c></tag> 585 <item> 586 <p>The filter has no knowledge of the log event. The next 587 primary filter, if any, is applied. If no more primary 588 filters exist, the value of the 589 primary <c>filter_default</c> configuration parameter 590 specifies if the log event shall be discarded or 591 forwarded to the handler part.</p> 592 </item> 593 </taglist> 594 <p>See section <seealso marker="logger_chapter#filters"> 595 Filters</seealso> in the User's Guide for more information 596 about filters.</p> 597 <p>Some built-in filters exist. These are defined 598 in <seealso marker="logger_filters"><c>logger_filters(3)</c></seealso>.</p> 599 </desc> 600 </func> 601 602 <func> 603 <name name="get_config" arity="0" since="OTP 21.0"/> 604 <fsummary>Look up the current Logger configuration</fsummary> 605 <desc> 606 <p>Look up all current Logger configuration, including primary, 607 handler, and proxy configuration, and module level settings.</p> 608 </desc> 609 </func> 610 611 <func> 612 <name name="get_handler_config" arity="0" since="OTP 21.0"/> 613 <fsummary>Look up the current configuration for all handlers.</fsummary> 614 <desc> 615 <p>Look up the current configuration for all handlers.</p> 616 </desc> 617 </func> 618 619 <func> 620 <name name="get_handler_config" arity="1" since="OTP 21.0"/> 621 <fsummary>Look up the current configuration for the given 622 handler.</fsummary> 623 <desc> 624 <p>Look up the current configuration for the given handler.</p> 625 </desc> 626 </func> 627 628 <func> 629 <name name="get_handler_ids" arity="0" since="OTP 21.0"/> 630 <fsummary>Look up the identities for all installed handlers.</fsummary> 631 <desc> 632 <p>Look up the identities for all installed handlers.</p> 633 </desc> 634 </func> 635 636 <func> 637 <name name="get_primary_config" arity="0" since="OTP 21.0"/> 638 <fsummary>Look up the current primary configuration for Logger.</fsummary> 639 <desc> 640 <p>Look up the current primary configuration for Logger.</p> 641 </desc> 642 </func> 643 644 <func> 645 <name name="get_proxy_config" arity="0" since="OTP 21.3"/> 646 <fsummary>Look up the current configuration for the Logger proxy.</fsummary> 647 <desc> 648 <p>Look up the current configuration for the Logger proxy.</p> 649 <p>For more information about the proxy, see 650 section <seealso marker="logger_chapter#proxy">Logger 651 Proxy</seealso> in the Kernel User's Guide.</p> 652 </desc> 653 </func> 654 655 <func> 656 <name name="get_module_level" arity="0" since="OTP 21.0"/> 657 <fsummary>Look up all current module levels.</fsummary> 658 <desc> 659 <p>Look up all current module levels. Returns a list 660 containing one <c>{Module,Level}</c> element for each module 661 for which the module level was previously set 662 with <seealso marker="#set_module_level-2"> 663 <c>set_module_level/2</c></seealso>.</p> 664 </desc> 665 </func> 666 667 <func> 668 <name name="get_module_level" arity="1" since="OTP 21.0"/> 669 <fsummary>Look up the current level for the given modules.</fsummary> 670 <desc> 671 <p>Look up the current level for the given modules. Returns a 672 list containing one <c>{Module,Level}</c> element for each 673 of the given modules for which the module level was 674 previously set with <seealso marker="#set_module_level-2"> 675 <c>set_module_level/2</c></seealso>.</p> 676 </desc> 677 </func> 678 679 <func> 680 <name name="get_process_metadata" arity="0" since="OTP 21.0"/> 681 <fsummary>Retrieve data set with set_process_metadata/1.</fsummary> 682 <desc> 683 <p>Retrieve data set 684 with <seealso marker="#set_process_metadata-1"> 685 <c>set_process_metadata/1</c></seealso> or 686 <seealso marker="#update_process_metadata-1"> 687 <c>update_process_metadata/1</c></seealso>.</p> 688 </desc> 689 </func> 690 691 <func> 692 <name name="i" arity="0" since="OTP 21.3"/> 693 <name name="i" arity="1" since="OTP 21.3"/> 694 <fsummary>Pretty print the Logger configuration.</fsummary> 695 <desc> 696 <p>Pretty print the Logger configuration.</p> 697 </desc> 698 </func> 699 700 <func> 701 <name name="remove_handler" arity="1" since="OTP 21.0"/> 702 <fsummary>Remove the handler with the specified identity.</fsummary> 703 <desc> 704 <p>Remove the handler identified by <c><anno>HandlerId</anno></c>.</p> 705 </desc> 706 </func> 707 708 <func> 709 <name name="remove_handler_filter" arity="2" since="OTP 21.0"/> 710 <fsummary>Remove a filter from the specified handler.</fsummary> 711 <desc> 712 <p>Remove the filter identified 713 by <c><anno>FilterId</anno></c> from the handler identified 714 by <c><anno>HandlerId</anno></c>.</p> 715 </desc> 716 </func> 717 718 <func> 719 <name name="remove_primary_filter" arity="1" since="OTP 21.0"/> 720 <fsummary>Remove a primary filter from Logger.</fsummary> 721 <desc> 722 <p>Remove the primary filter identified 723 by <c><anno>FilterId</anno></c> from Logger.</p> 724 </desc> 725 </func> 726 727 <func> 728 <name name="set_application_level" arity="2" since="OTP 21.1"/> 729 <fsummary>Set the log level for all modules in the specified application.</fsummary> 730 <desc> 731 <p>Set the log level for all the modules of the specified application.</p> 732 <p>This function is a convenience function that calls 733 <seealso marker="#set_module_level/2">logger:set_module_level/2</seealso> 734 for each module associated with an application.</p> 735 </desc> 736 </func> 737 738 <func> 739 <name name="set_handler_config" arity="2" since="OTP 21.0"/> 740 <fsummary>Set configuration data for the specified handler.</fsummary> 741 <desc> 742 <p>Set configuration data for the specified handler. This 743 overwrites the current handler configuration.</p> 744 <p>To modify the existing configuration, 745 use <seealso marker="#update_handler_config-2"> 746 <c>update_handler_config/2</c></seealso>, or, if a more 747 complex merge is needed, read the current configuration 748 with <seealso marker="#get_handler_config-1"><c>get_handler_config/1</c> 749 </seealso>, then do the merge before writing the new 750 configuration back with this function.</p> 751 <p>If a key is removed compared to the current configuration, 752 and the key is known by Logger, the default value is used. If 753 it is a custom key, then it is up to the handler 754 implementation if the value is removed or a default value is 755 inserted.</p> 756 </desc> 757 </func> 758 759 <func> 760 <name name="set_handler_config" arity="3" clause_i="1" since="OTP 21.0"/> 761 <name name="set_handler_config" arity="3" clause_i="2" since="OTP 21.0"/> 762 <name name="set_handler_config" arity="3" clause_i="3" since="OTP 21.0"/> 763 <name name="set_handler_config" arity="3" clause_i="4" since="OTP 21.0"/> 764 <name name="set_handler_config" arity="3" clause_i="5" since="OTP 21.0"/> 765 <fsummary>Add or update configuration data for the specified 766 handler.</fsummary> 767 <type variable="HandlerId"/> 768 <type variable="Level" name_i="1"/> 769 <type variable="FilterDefault" name_i="2"/> 770 <type variable="Filters" name_i="3"/> 771 <type variable="Formatter" name_i="4"/> 772 <type variable="Config" name_i="5"/> 773 <type variable="Return"/> 774 <desc> 775 <p>Add or update configuration data for the specified 776 handler. If the given <c><anno>Key</anno></c> already 777 exists, its associated value will be changed 778 to the given value. If it does not exist, it will 779 be added.</p> 780 <p>If the value is incomplete, which for example can be the 781 case for the <c>config</c> key, it is up to the handler 782 implementation how the unspecified parts are set. For all 783 handlers in the Kernel application, unspecified data for 784 the <c>config</c> key is set to default values. To update 785 only specified data, and keep the existing configuration for 786 the rest, use <seealso marker="#update_handler_config-3"> 787 <c>update_handler_config/3</c></seealso>.</p> 788 <p>See the definition of 789 the <seealso marker="#type-handler_config"> 790 <c>handler_config()</c></seealso> type for more 791 information about the different parameters.</p> 792 </desc> 793 </func> 794 795 <func> 796 <name name="set_primary_config" arity="1" since="OTP 21.0"/> 797 <fsummary>Set primary configuration data for Logger.</fsummary> 798 <desc> 799 <p>Set primary configuration data for Logger. This 800 overwrites the current configuration.</p> 801 <p>To modify the existing configuration, 802 use <seealso marker="#update_primary_config-1"> 803 <c>update_primary_config/1</c></seealso>, or, if a more 804 complex merge is needed, read the current configuration 805 with <seealso marker="#get_primary_config-0"><c>get_primary_config/0</c> 806 </seealso>, then do the merge before writing the new 807 configuration back with this function.</p> 808 <p>If a key is removed compared to the current configuration, 809 the default value is used.</p> 810 </desc> 811 </func> 812 813 <func> 814 <name name="set_primary_config" arity="2" clause_i="1" since="OTP 21.0"/> 815 <name name="set_primary_config" arity="2" clause_i="2" since="OTP 21.0"/> 816 <name name="set_primary_config" arity="2" clause_i="3" since="OTP 21.0"/> 817 <fsummary>Add or update primary configuration data for Logger.</fsummary> 818 <type variable="Level" name_i="1"/> 819 <type variable="FilterDefault" name_i="2"/> 820 <type variable="Filters" name_i="3"/> 821 <desc> 822 <p>Add or update primary configuration data for Logger. If the 823 given <c><anno>Key</anno></c> already exists, its associated 824 value will be changed to the given value. If it does not 825 exist, it will be added.</p> 826 </desc> 827 </func> 828 829 <func> 830 <name name="set_proxy_config" arity="1" since="OTP 21.3"/> 831 <fsummary>Set configuration data for the Logger proxy.</fsummary> 832 <desc> 833 <p>Set configuration data for the Logger proxy. This 834 overwrites the current proxy configuration. Keys that are not 835 specified in the <c><anno>Config</anno></c> map gets default 836 values.</p> 837 <p>To modify the existing configuration, 838 use <seealso marker="#update_proxy_config-1"> 839 <c>update_proxy_config/1</c></seealso>, or, if a more 840 complex merge is needed, read the current configuration 841 with <seealso marker="#get_proxy_config-0"><c>get_proxy_config/0</c> 842 </seealso>, then do the merge before writing the new 843 configuration back with this function.</p> 844 <p>For more information about the proxy, see 845 section <seealso marker="logger_chapter#proxy">Logger 846 Proxy</seealso> in the Kernel User's Guide.</p> 847 </desc> 848 </func> 849 850 <func> 851 <name name="set_module_level" arity="2" since="OTP 21.0"/> 852 <fsummary>Set the log level for the specified modules.</fsummary> 853 <desc> 854 <p>Set the log level for the specified modules.</p> 855 <p>The log level for a module overrides the primary log level 856 of Logger for log events originating from the module in 857 question. Notice, however, that it does not override the 858 level configuration for any handler.</p> 859 <p>For example: Assume that the primary log level for Logger 860 is <c>info</c>, and there is one handler, <c>h1</c>, with 861 level <c>info</c> and one handler, <c>h2</c>, with 862 level <c>debug</c>.</p> 863 <p>With this configuration, no debug messages will be logged, 864 since they are all stopped by the primary log level.</p> 865 <p>If the level for <c>mymodule</c> is now set 866 to <c>debug</c>, then debug events from this module will be 867 logged by the handler <c>h2</c>, but not by 868 handler <c>h1</c>.</p> 869 <p>Debug events from other modules are still not logged.</p> 870 <p>To change the primary log level for Logger, use 871 <seealso marker="#set_primary_config/2"> 872 <c>set_primary_config(level, Level)</c></seealso>.</p> 873 <p>To change the log level for a handler, use 874 <seealso marker="#set_handler_config/3"> 875 <c>set_handler_config(HandlerId, level, Level)</c> 876 </seealso>.</p> 877 <note> 878 <p>The originating module for a log event is only detected 879 if the key <c>mfa</c> exists in the metadata, and is 880 associated with <c>{Module, Function, Arity}</c>. When log 881 macros are used, this association is automatically added 882 to all log events. If an API function is called directly, 883 without using a macro, the logging client must explicitly 884 add this information if module levels shall have any 885 effect.</p> 886 </note> 887 </desc> 888 </func> 889 890 <func> 891 <name name="set_process_metadata" arity="1" since="OTP 21.0"/> 892 <fsummary>Set metadata to use when logging from current process.</fsummary> 893 <desc> 894 <p>Set metadata which Logger shall automatically insert in 895 all log events produced on the current process.</p> 896 <p>Location data produced by the log macros, and/or metadata 897 given as argument to the log call (API function or macro), 898 are merged with the process metadata. If the same keys 899 occur, values from the metadata argument to the log call 900 overwrite values from the process metadata, which in turn 901 overwrite values from the location data.</p> 902 <p>Subsequent calls to this function overwrites previous data 903 set. To update existing data instead of overwriting it, 904 see <seealso marker="#update_process_metadata-1"> 905 <c>update_process_metadata/1</c></seealso>.</p> 906 </desc> 907 </func> 908 909 <func> 910 <name name="unset_application_level" arity="1" since="OTP 21.1"/> 911 <fsummary>Unset the log level for all modules in the specified application.</fsummary> 912 <desc> 913 <p>Unset the log level for all the modules of the specified application.</p> 914 <p>This function is a convinience function that calls 915 <seealso marker="#unset_module_level/1">logger:unset_module_level/2</seealso> 916 for each module associated with an application.</p> 917 </desc> 918 </func> 919 920 <func> 921 <name name="unset_module_level" arity="0" since="OTP 21.0"/> 922 <fsummary>Remove module specific log settings for all modules.</fsummary> 923 <desc> 924 <p>Remove module specific log settings. After this, the 925 primary log level is used for all modules.</p> 926 </desc> 927 </func> 928 929 <func> 930 <name name="unset_module_level" arity="1" since="OTP 21.0"/> 931 <fsummary>Remove module specific log settings for the given 932 modules.</fsummary> 933 <desc> 934 <p>Remove module specific log settings. After this, the 935 primary log level is used for the specified modules.</p> 936 </desc> 937 </func> 938 939 <func> 940 <name name="unset_process_metadata" arity="0" since="OTP 21.0"/> 941 <fsummary>Delete data set with set_process_metadata/1.</fsummary> 942 <desc> 943 <p>Delete data set 944 with <seealso marker="#set_process_metadata-1"> 945 <c>set_process_metadata/1</c></seealso> or 946 <seealso marker="#update_process_metadata-1"> 947 <c>update_process_metadata/1</c></seealso>.</p> 948 </desc> 949 </func> 950 951 <func> 952 <name name="update_formatter_config" arity="2" since="OTP 21.0"/> 953 <fsummary>Update the formatter configuration for the specified handler.</fsummary> 954 <desc> 955 <p>Update the formatter configuration for the specified handler.</p> 956 <p>The new configuration is merged with the existing formatter 957 configuration.</p> 958 <p>To overwrite the existing configuration without any merge, 959 use</p> 960 <pre> 961<seealso marker="#set_handler_config-3">set_handler_config(HandlerId, formatter, 962 {FormatterModule, FormatterConfig})</seealso>.</pre> 963 </desc> 964 </func> 965 966 <func> 967 <name name="update_formatter_config" arity="3" since="OTP 21.0"/> 968 <fsummary>Update the formatter configuration for the specified handler.</fsummary> 969 <desc> 970 <p>Update the formatter configuration for the specified handler.</p> 971 <p>This is equivalent to</p> 972 <pre> 973<seealso marker="#update_formatter_config-2">update_formatter_config(<anno>HandlerId</anno>, #{<anno>Key</anno> => <anno>Value</anno>})</seealso></pre> 974 </desc> 975 </func> 976 977 <func> 978 <name name="update_handler_config" arity="2" since="OTP 21.0"/> 979 <fsummary>Update configuration data for the specified handler.</fsummary> 980 <desc> 981 <p>Update configuration data for the specified handler. This function 982 behaves as if it was implemented as follows:</p> 983 <code type="erl"> 984{ok, {_, Old}} = logger:get_handler_config(HandlerId), 985logger:set_handler_config(HandlerId, maps:merge(Old, Config)). 986 </code> 987 <p>To overwrite the existing configuration without any merge, 988 use <seealso marker="#set_handler_config-2"><c>set_handler_config/2</c> 989 </seealso>.</p> 990 </desc> 991 </func> 992 993 <func> 994 <name name="update_handler_config" arity="3" clause_i="1" since="OTP 21.2"/> 995 <name name="update_handler_config" arity="3" clause_i="2" since="OTP 21.2"/> 996 <name name="update_handler_config" arity="3" clause_i="3" since="OTP 21.2"/> 997 <name name="update_handler_config" arity="3" clause_i="4" since="OTP 21.2"/> 998 <name name="update_handler_config" arity="3" clause_i="5" since="OTP 21.2"/> 999 <fsummary>Add or update configuration data for the specified 1000 handler.</fsummary> 1001 <type variable="HandlerId"/> 1002 <type variable="Level" name_i="1"/> 1003 <type variable="FilterDefault" name_i="2"/> 1004 <type variable="Filters" name_i="3"/> 1005 <type variable="Formatter" name_i="4"/> 1006 <type variable="Config" name_i="5"/> 1007 <type variable="Return"/> 1008 <desc> 1009 <p>Add or update configuration data for the specified 1010 handler. If the given <c><anno>Key</anno></c> already 1011 exists, its associated value will be changed 1012 to the given value. If it does not exist, it will 1013 be added.</p> 1014 <p>If the value is incomplete, which for example can be the 1015 case for the <c>config</c> key, it is up to the handler 1016 implementation how the unspecified parts are set. For all 1017 handlers in the Kernel application, unspecified data for 1018 the <c>config</c> key is not changed. To reset unspecified 1019 data to default values, 1020 use <seealso marker="#set_handler_config-3"> 1021 <c>set_handler_config/3</c></seealso>.</p> 1022 <p>See the definition of 1023 the <seealso marker="#type-handler_config"> 1024 <c>handler_config()</c></seealso> type for more 1025 information about the different parameters.</p> 1026 </desc> 1027 </func> 1028 1029 <func> 1030 <name name="update_primary_config" arity="1" since="OTP 21.0"/> 1031 <fsummary>Update primary configuration data for Logger.</fsummary> 1032 <desc> 1033 <p>Update primary configuration data for Logger. This function 1034 behaves as if it was implemented as follows:</p> 1035 <code type="erl"> 1036Old = logger:get_primary_config(), 1037logger:set_primary_config(maps:merge(Old, Config)). 1038 </code> 1039 <p>To overwrite the existing configuration without any merge, 1040 use <seealso marker="#set_primary_config-1"><c>set_primary_config/1</c> 1041 </seealso>.</p> 1042 </desc> 1043 </func> 1044 1045 <func> 1046 <name name="update_process_metadata" arity="1" since="OTP 21.0"/> 1047 <fsummary>Set or update metadata to use when logging from 1048 current process.</fsummary> 1049 <desc> 1050 <p>Set or update metadata to use when logging from current 1051 process</p> 1052 <p>If process metadata exists for the current process, this 1053 function behaves as if it was implemented as follows:</p> 1054 <code type="erl"> 1055logger:set_process_metadata(maps:merge(logger:get_process_metadata(), Meta)). 1056 </code> 1057 <p>If no process metadata exists, the function behaves as 1058 <seealso marker="#set_process_metadata-1"> 1059 <c>set_process_metadata/1</c> 1060 </seealso>.</p> 1061 </desc> 1062 </func> 1063 1064 <func> 1065 <name name="update_proxy_config" arity="1" since="OTP 21.3"/> 1066 <fsummary>Update configuration data for the Logger proxy.</fsummary> 1067 <desc> 1068 <p>Update configuration data for the Logger proxy. This function 1069 behaves as if it was implemented as follows:</p> 1070 <code type="erl"> 1071Old = logger:get_proxy_config(), 1072logger:set_proxy_config(maps:merge(Old, Config)). 1073 </code> 1074 <p>To overwrite the existing configuration without any merge, 1075 use <seealso marker="#set_proxy_config-1"><c>set_proxy_config/1</c> 1076 </seealso>.</p> 1077 <p>For more information about the proxy, see 1078 section <seealso marker="logger_chapter#proxy">Logger 1079 Proxy</seealso> in the Kernel User's Guide.</p> 1080 </desc> 1081 </func> 1082 </funcs> 1083 1084 <section> 1085 <marker id="misc_API"/> 1086 <title>Miscellaneous API functions</title> 1087 </section> 1088 <funcs> 1089 <func> 1090 <name name="compare_levels" arity="2" since="OTP 21.0"/> 1091 <fsummary>Compare the severity of two log levels.</fsummary> 1092 <desc> 1093 <p>Compare the severity of two log levels. Returns <c>gt</c> 1094 if <c>Level1</c> is more severe than 1095 <c>Level2</c>, <c>lt</c> if <c>Level1</c> is less severe, 1096 and <c>eq</c> if the levels are equal.</p> 1097 </desc> 1098 </func> 1099 1100 <func> 1101 <name name="format_report" arity="1" since="OTP 21.0"/> 1102 <fsummary>Convert a log message on report form to {Format, Args}.</fsummary> 1103 <desc> 1104 <p>Convert a log message on report form to <c>{Format, 1105 Args}</c>. This is the default report callback used 1106 by <seealso marker="logger_formatter"> 1107 <c>logger_formatter(3)</c></seealso> when no custom report 1108 callback is found. See 1109 section <seealso marker="logger_chapter#log_message">Log 1110 Message</seealso> in the Kernel User's Guide for 1111 information about report callbacks and valid forms of log 1112 messages.</p> 1113 <p>The function produces lines of <c>Key: Value</c> from 1114 key-value lists. Strings are printed with <c>~ts</c> and 1115 other terms with <c>~tp</c>.</p> 1116 <p>If <c><anno>Report</anno></c> is a map, it is converted to 1117 a key-value list before formatting as such.</p> 1118 </desc> 1119 </func> 1120 1121 <func> 1122 <name name="timestamp" arity="0" since="OTP 21.3"/> 1123 <fsummary>Return a timestamp to insert in meta data for a log 1124 event.</fsummary> 1125 <desc> 1126 <p>Return a timestamp that can be inserted as the <c>time</c> 1127 field in the meta data for a log event. It is produced with 1128 <seealso marker="kernel:os#system_time-1"> 1129 <c>os:system_time(microsecond)</c></seealso>.</p> 1130 <p>Notice that Logger automatically inserts a timestamp in the 1131 meta data unless it already exists. This function is 1132 exported for the rare case when the timestamp must be taken 1133 at a different point in time than when the log event is 1134 issued.</p> 1135 </desc> 1136 </func> 1137 1138 </funcs> 1139 1140 <section> 1141 <marker id="handler_callback_functions"/> 1142 <title>Handler Callback Functions</title> 1143 <p>The following functions are to be exported from a handler 1144 callback module.</p> 1145 </section> 1146 1147 <funcs> 1148 <func> 1149 <name since="OTP 21.0">HModule:adding_handler(Config1) -> {ok, Config2} | {error, 1150 Reason}</name> 1151 <fsummary>An instance of this handler is about to be added.</fsummary> 1152 <type> 1153 <v>Config1 = Config2 = 1154 <seealso marker="#type-handler_config">handler_config()</seealso></v> 1155 <v>Reason = term()</v> 1156 </type> 1157 <desc> 1158 <p>This callback function is optional.</p> 1159 <p>The function is called on a temporary process when an new 1160 handler is about to be added. The purpose is to verify the 1161 configuration and initiate all resources needed by the 1162 handler.</p> 1163 <p>The handler identity is associated with the <c>id</c> key 1164 in <c>Config1</c>.</p> 1165 <p>If everything succeeds, the callback function can add 1166 possible default values or internal state values to the 1167 configuration, and return the adjusted map 1168 in <c>{ok,Config2}</c>.</p> 1169 <p>If the configuration is faulty, or if the initiation fails, 1170 the callback function must return <c>{error,Reason}</c>.</p> 1171 </desc> 1172 </func> 1173 1174 <func> 1175 <name since="OTP 21.2">HModule:changing_config(SetOrUpdate, OldConfig, NewConfig) -> {ok, Config} | {error, Reason}</name> 1176 <fsummary>The configuration for this handler is about to change.</fsummary> 1177 <type> 1178 <v>SetOrUpdate = set | update</v> 1179 <v>OldConfig = NewConfig = Config = 1180 <seealso marker="#type-handler_config">handler_config()</seealso></v> 1181 <v>Reason = term()</v> 1182 </type> 1183 <desc> 1184 <p>This callback function is optional.</p> 1185 <p>The function is called on a temporary process when the 1186 configuration for a handler is about to change. The purpose 1187 is to verify and act on the new configuration.</p> 1188 <p><c>OldConfig</c> is the existing configuration 1189 and <c>NewConfig</c> is the new configuration.</p> 1190 <p>The handler identity is associated with the <c>id</c> key 1191 in <c>OldConfig</c>.</p> 1192 <p><c>SetOrUpdate</c> has the value <c>set</c> if the 1193 configuration change originates from a call to 1194 <seealso marker="#set_handler_config-2"> 1195 <c>set_handler_config/2,3</c></seealso>, and <c>update</c> 1196 if it originates from <seealso marker="#update_handler_config-2"> 1197 <c>update_handler_config/2,3</c></seealso>. The handler can 1198 use this parameteter to decide how to update the value of 1199 the <c>config</c> field, that is, the handler specific 1200 configuration data. Typically, if <c>SetOrUpdate</c> 1201 equals <c>set</c>, values that are not specified must be 1202 given their default values. If <c>SetOrUpdate</c> 1203 equals <c>update</c>, the values found in <c>OldConfig</c> 1204 must be used instead.</p> 1205 <p>If everything succeeds, the callback function must return a 1206 possibly adjusted configuration in <c>{ok,Config}</c>.</p> 1207 <p>If the configuration is faulty, the callback function must 1208 return <c>{error,Reason}</c>.</p> 1209 </desc> 1210 </func> 1211 1212 <func> 1213 <name since="OTP 21.2">HModule:filter_config(Config) -> FilteredConfig</name> 1214 <fsummary>Remove internal data from configuration.</fsummary> 1215 <type> 1216 <v>Config = FilteredConfig = 1217 <seealso marker="#type-handler_config">handler_config()</seealso></v> 1218 </type> 1219 <desc> 1220 <p>This callback function is optional.</p> 1221 <p>The function is called when one of the Logger API functions 1222 for fetching the handler configuration is called, for 1223 example 1224 <seealso marker="#get_handler_config-1"> 1225 <c>logger:get_handler_config/1</c></seealso>.</p> 1226 <p>It allows the handler to remove internal data fields from 1227 its configuration data before it is returned to the 1228 caller.</p> 1229 </desc> 1230 </func> 1231 1232 <func> 1233 <name since="OTP 21.0">HModule:log(LogEvent, Config) -> void()</name> 1234 <fsummary>Log the given log event.</fsummary> 1235 <type> 1236 <v>LogEvent = 1237 <seealso marker="#type-log_event">log_event()</seealso></v> 1238 <v>Config = 1239 <seealso marker="#type-handler_config">handler_config()</seealso></v> 1240 </type> 1241 <desc> 1242 <p>This callback function is mandatory.</p> 1243 <p>The function is called when all primary filters and all 1244 handler filters for the handler in question have passed for 1245 the given log event. It is called on the client process, that 1246 is, the process that issued the log event.</p> 1247 <p>The handler identity is associated with the <c>id</c> key 1248 in <c>Config</c>.</p> 1249 <p>The handler must log the event.</p> 1250 <p>The return value from this function is ignored by 1251 Logger.</p> 1252 </desc> 1253 </func> 1254 1255 <func> 1256 <name since="OTP 21.0">HModule:removing_handler(Config) -> ok</name> 1257 <fsummary>The given handler is about to be removed.</fsummary> 1258 <type> 1259 <v>Config = 1260 <seealso marker="#type-handler_config">handler_config()</seealso></v> 1261 </type> 1262 <desc> 1263 <p>This callback function is optional.</p> 1264 <p>The function is called on a temporary process when a 1265 handler is about to be removed. The purpose is to release 1266 all resources used by the handler.</p> 1267 <p>The handler identity is associated with the <c>id</c> key 1268 in <c>Config</c>.</p> 1269 <p>The return value is ignored by Logger.</p> 1270 </desc> 1271 </func> 1272 1273 </funcs> 1274 1275 <section> 1276 <marker id="formatter_callback_functions"/> 1277 <title>Formatter Callback Functions</title> 1278 <p>The following functions are to be exported from a formatter 1279 callback module.</p> 1280 </section> 1281 1282 <funcs> 1283 <func> 1284 <name since="OTP 21.0">FModule:check_config(FConfig) -> ok | {error, Reason}</name> 1285 <fsummary>Validate the given formatter configuration.</fsummary> 1286 <type> 1287 <v>FConfig = 1288 <seealso marker="#type-formatter_config">formatter_config()</seealso></v> 1289 <v>Reason = term()</v> 1290 </type> 1291 <desc> 1292 <p>This callback function is optional.</p> 1293 <p>The function is called by a Logger when formatter 1294 configuration is set or modified. The formatter must 1295 validate the given configuration and return <c>ok</c> if it 1296 is correct, and <c>{error,Reason}</c> if it is faulty.</p> 1297 <p>The following Logger API functions can trigger this callback:</p> 1298 <list> 1299 <item><seealso marker="logger#add_handler-3"> 1300 <c>logger:add_handler/3</c></seealso></item> 1301 <item><seealso marker="logger#set_handler_config-2"> 1302 <c>logger:set_handler_config/2,3</c></seealso></item> 1303 <item><seealso marker="logger#update_handler_config-2"> 1304 <c>logger:update_handler_config/2,3</c></seealso></item> 1305 <item><seealso marker="logger#update_formatter_config-2"> 1306 <c>logger:update_formatter_config/2</c></seealso></item> 1307 </list> 1308 <p>See <seealso marker="logger_formatter"> 1309 <c>logger_formatter(3)</c></seealso> 1310 for an example implementation. <c>logger_formatter</c> is the 1311 default formatter used by Logger.</p> 1312 </desc> 1313 </func> 1314 <func> 1315 <name since="OTP 21.0">FModule:format(LogEvent, FConfig) -> FormattedLogEntry</name> 1316 <fsummary>Format the given log event.</fsummary> 1317 <type> 1318 <v>LogEvent = 1319 <seealso marker="#type-log_event">log_event()</seealso></v> 1320 <v>FConfig = 1321 <seealso marker="#type-formatter_config">formatter_config()</seealso></v> 1322 <v>FormattedLogEntry = 1323 <seealso marker="unicode#type-chardata">unicode:chardata()</seealso></v> 1324 </type> 1325 <desc> 1326 <p>This callback function is mandatory.</p> 1327 <p>The function can be called by a log handler to convert a 1328 log event term to a printable string. The returned value 1329 can, for example, be printed as a log entry to the console 1330 or a file using <seealso marker="stdlib:io#put_chars-1"> 1331 <c>io:put_chars/1,2</c></seealso>.</p> 1332 <p>See <seealso marker="logger_formatter"> 1333 <c>logger_formatter(3)</c></seealso> 1334 for an example implementation. <c>logger_formatter</c> is the 1335 default formatter used by Logger.</p> 1336 </desc> 1337 </func> 1338 </funcs> 1339 1340 <section> 1341 <title>See Also</title> 1342 <p> 1343 <seealso marker="config"><c>config(4)</c></seealso>, 1344 <seealso marker="erts:erlang"><c>erlang(3)</c></seealso>, 1345 <seealso marker="stdlib:io"><c>io(3)</c></seealso>, 1346 <seealso marker="logger_disk_log_h"><c>logger_disk_log_h(3)</c></seealso>, 1347 <seealso marker="logger_filters"><c>logger_filters(3)</c></seealso>, 1348 <seealso marker="logger_formatter"><c>logger_formatter(3)</c></seealso>, 1349 <seealso marker="logger_std_h"><c>logger_std_h(3)</c></seealso>, 1350 <seealso marker="stdlib:unicode"><c>unicode(3)</c></seealso> 1351 </p> 1352 </section> 1353</erlref> 1354