MediaWiki REL1_28
ApiQueryRevisionsBase.php
Go to the documentation of this file.
1<?php
33
36
37 protected $fld_ids = false, $fld_flags = false, $fld_timestamp = false,
38 $fld_size = false, $fld_sha1 = false, $fld_comment = false,
39 $fld_parsedcomment = false, $fld_user = false, $fld_userid = false,
40 $fld_content = false, $fld_tags = false, $fld_contentmodel = false, $fld_parsetree = false;
41
42 public function execute() {
43 $this->run();
44 }
45
46 public function executeGenerator( $resultPageSet ) {
47 $this->run( $resultPageSet );
48 }
49
54 abstract protected function run( ApiPageSet $resultPageSet = null );
55
61 protected function parseParameters( $params ) {
62 if ( !is_null( $params['difftotext'] ) ) {
63 $this->difftotext = $params['difftotext'];
64 $this->difftotextpst = $params['difftotextpst'];
65 } elseif ( !is_null( $params['diffto'] ) ) {
66 if ( $params['diffto'] == 'cur' ) {
67 $params['diffto'] = 0;
68 }
69 if ( ( !ctype_digit( $params['diffto'] ) || $params['diffto'] < 0 )
70 && $params['diffto'] != 'prev' && $params['diffto'] != 'next'
71 ) {
72 $p = $this->getModulePrefix();
73 $this->dieUsage(
74 "{$p}diffto must be set to a non-negative number, \"prev\", \"next\" or \"cur\"",
75 'diffto'
76 );
77 }
78 // Check whether the revision exists and is readable,
79 // DifferenceEngine returns a rather ambiguous empty
80 // string if that's not the case
81 if ( $params['diffto'] != 0 ) {
82 $difftoRev = Revision::newFromId( $params['diffto'] );
83 if ( !$difftoRev ) {
84 $this->dieUsageMsg( [ 'nosuchrevid', $params['diffto'] ] );
85 }
86 if ( !$difftoRev->userCan( Revision::DELETED_TEXT, $this->getUser() ) ) {
87 $this->setWarning( "Couldn't diff to r{$difftoRev->getId()}: content is hidden" );
88 $params['diffto'] = null;
89 }
90 }
91 $this->diffto = $params['diffto'];
92 }
93
94 $prop = array_flip( $params['prop'] );
95
96 $this->fld_ids = isset( $prop['ids'] );
97 $this->fld_flags = isset( $prop['flags'] );
98 $this->fld_timestamp = isset( $prop['timestamp'] );
99 $this->fld_comment = isset( $prop['comment'] );
100 $this->fld_parsedcomment = isset( $prop['parsedcomment'] );
101 $this->fld_size = isset( $prop['size'] );
102 $this->fld_sha1 = isset( $prop['sha1'] );
103 $this->fld_content = isset( $prop['content'] );
104 $this->fld_contentmodel = isset( $prop['contentmodel'] );
105 $this->fld_userid = isset( $prop['userid'] );
106 $this->fld_user = isset( $prop['user'] );
107 $this->fld_tags = isset( $prop['tags'] );
108 $this->fld_parsetree = isset( $prop['parsetree'] );
109
110 if ( !empty( $params['contentformat'] ) ) {
111 $this->contentFormat = $params['contentformat'];
112 }
113
114 $this->limit = $params['limit'];
115
116 $this->fetchContent = $this->fld_content || !is_null( $this->diffto )
117 || !is_null( $this->difftotext ) || $this->fld_parsetree;
118
119 $smallLimit = false;
120 if ( $this->fetchContent ) {
121 $smallLimit = true;
122 $this->expandTemplates = $params['expandtemplates'];
123 $this->generateXML = $params['generatexml'];
124 $this->parseContent = $params['parse'];
125 if ( $this->parseContent ) {
126 // Must manually initialize unset limit
127 if ( is_null( $this->limit ) ) {
128 $this->limit = 1;
129 }
130 }
131 if ( isset( $params['section'] ) ) {
132 $this->section = $params['section'];
133 } else {
134 $this->section = false;
135 }
136 }
137
138 $userMax = $this->parseContent ? 1 : ( $smallLimit ? ApiBase::LIMIT_SML1 : ApiBase::LIMIT_BIG1 );
139 $botMax = $this->parseContent ? 1 : ( $smallLimit ? ApiBase::LIMIT_SML2 : ApiBase::LIMIT_BIG2 );
140 if ( $this->limit == 'max' ) {
141 $this->limit = $this->getMain()->canApiHighLimits() ? $botMax : $userMax;
142 if ( $this->setParsedLimit ) {
143 $this->getResult()->addParsedLimit( $this->getModuleName(), $this->limit );
144 }
145 }
146
147 if ( is_null( $this->limit ) ) {
148 $this->limit = 10;
149 }
150 $this->validateLimit( 'limit', $this->limit, 1, $userMax, $botMax );
151 }
152
160 protected function extractRevisionInfo( Revision $revision, $row ) {
161 $title = $revision->getTitle();
162 $user = $this->getUser();
163 $vals = [];
164 $anyHidden = false;
165
166 if ( $this->fld_ids ) {
167 $vals['revid'] = intval( $revision->getId() );
168 if ( !is_null( $revision->getParentId() ) ) {
169 $vals['parentid'] = intval( $revision->getParentId() );
170 }
171 }
172
173 if ( $this->fld_flags ) {
174 $vals['minor'] = $revision->isMinor();
175 }
176
177 if ( $this->fld_user || $this->fld_userid ) {
178 if ( $revision->isDeleted( Revision::DELETED_USER ) ) {
179 $vals['userhidden'] = true;
180 $anyHidden = true;
181 }
182 if ( $revision->userCan( Revision::DELETED_USER, $user ) ) {
183 if ( $this->fld_user ) {
184 $vals['user'] = $revision->getUserText( Revision::RAW );
185 }
186 $userid = $revision->getUser( Revision::RAW );
187 if ( !$userid ) {
188 $vals['anon'] = true;
189 }
190
191 if ( $this->fld_userid ) {
192 $vals['userid'] = $userid;
193 }
194 }
195 }
196
197 if ( $this->fld_timestamp ) {
198 $vals['timestamp'] = wfTimestamp( TS_ISO_8601, $revision->getTimestamp() );
199 }
200
201 if ( $this->fld_size ) {
202 if ( !is_null( $revision->getSize() ) ) {
203 $vals['size'] = intval( $revision->getSize() );
204 } else {
205 $vals['size'] = 0;
206 }
207 }
208
209 if ( $this->fld_sha1 ) {
210 if ( $revision->isDeleted( Revision::DELETED_TEXT ) ) {
211 $vals['sha1hidden'] = true;
212 $anyHidden = true;
213 }
214 if ( $revision->userCan( Revision::DELETED_TEXT, $user ) ) {
215 if ( $revision->getSha1() != '' ) {
216 $vals['sha1'] = Wikimedia\base_convert( $revision->getSha1(), 36, 16, 40 );
217 } else {
218 $vals['sha1'] = '';
219 }
220 }
221 }
222
223 if ( $this->fld_contentmodel ) {
224 $vals['contentmodel'] = $revision->getContentModel();
225 }
226
227 if ( $this->fld_comment || $this->fld_parsedcomment ) {
228 if ( $revision->isDeleted( Revision::DELETED_COMMENT ) ) {
229 $vals['commenthidden'] = true;
230 $anyHidden = true;
231 }
232 if ( $revision->userCan( Revision::DELETED_COMMENT, $user ) ) {
233 $comment = $revision->getComment( Revision::RAW );
234
235 if ( $this->fld_comment ) {
236 $vals['comment'] = $comment;
237 }
238
239 if ( $this->fld_parsedcomment ) {
240 $vals['parsedcomment'] = Linker::formatComment( $comment, $title );
241 }
242 }
243 }
244
245 if ( $this->fld_tags ) {
246 if ( $row->ts_tags ) {
247 $tags = explode( ',', $row->ts_tags );
248 ApiResult::setIndexedTagName( $tags, 'tag' );
249 $vals['tags'] = $tags;
250 } else {
251 $vals['tags'] = [];
252 }
253 }
254
255 $content = null;
257 if ( $this->fetchContent ) {
258 $content = $revision->getContent( Revision::FOR_THIS_USER, $this->getUser() );
259 // Expand templates after getting section content because
260 // template-added sections don't count and Parser::preprocess()
261 // will have less input
262 if ( $content && $this->section !== false ) {
263 $content = $content->getSection( $this->section, false );
264 if ( !$content ) {
265 $this->dieUsage(
266 "There is no section {$this->section} in r" . $revision->getId(),
267 'nosuchsection'
268 );
269 }
270 }
271 if ( $revision->isDeleted( Revision::DELETED_TEXT ) ) {
272 $vals['texthidden'] = true;
273 $anyHidden = true;
274 } elseif ( !$content ) {
275 $vals['textmissing'] = true;
276 }
277 }
278 if ( $this->fld_parsetree || ( $this->fld_content && $this->generateXML ) ) {
279 if ( $content ) {
280 if ( $content->getModel() === CONTENT_MODEL_WIKITEXT ) {
281 $t = $content->getNativeData(); # note: don't set $text
282
283 $wgParser->startExternalParse(
284 $title,
285 ParserOptions::newFromContext( $this->getContext() ),
286 Parser::OT_PREPROCESS
287 );
288 $dom = $wgParser->preprocessToDom( $t );
289 if ( is_callable( [ $dom, 'saveXML' ] ) ) {
290 $xml = $dom->saveXML();
291 } else {
292 $xml = $dom->__toString();
293 }
294 $vals['parsetree'] = $xml;
295 } else {
296 $vals['badcontentformatforparsetree'] = true;
297 $this->setWarning( 'Conversion to XML is supported for wikitext only, ' .
298 $title->getPrefixedDBkey() .
299 ' uses content model ' . $content->getModel() );
300 }
301 }
302 }
303
304 if ( $this->fld_content && $content ) {
305 $text = null;
306
307 if ( $this->expandTemplates && !$this->parseContent ) {
308 # XXX: implement template expansion for all content types in ContentHandler?
309 if ( $content->getModel() === CONTENT_MODEL_WIKITEXT ) {
310 $text = $content->getNativeData();
311
312 $text = $wgParser->preprocess(
313 $text,
314 $title,
315 ParserOptions::newFromContext( $this->getContext() )
316 );
317 } else {
318 $this->setWarning( 'Template expansion is supported for wikitext only, ' .
319 $title->getPrefixedDBkey() .
320 ' uses content model ' . $content->getModel() );
321 $vals['badcontentformat'] = true;
322 $text = false;
323 }
324 }
325 if ( $this->parseContent ) {
326 $po = $content->getParserOutput(
327 $title,
328 $revision->getId(),
329 ParserOptions::newFromContext( $this->getContext() )
330 );
331 $text = $po->getText();
332 }
333
334 if ( $text === null ) {
335 $format = $this->contentFormat ?: $content->getDefaultFormat();
336 $model = $content->getModel();
337
338 if ( !$content->isSupportedFormat( $format ) ) {
339 $name = $title->getPrefixedDBkey();
340 $this->setWarning( "The requested format {$this->contentFormat} is not " .
341 "supported for content model $model used by $name" );
342 $vals['badcontentformat'] = true;
343 $text = false;
344 } else {
345 $text = $content->serialize( $format );
346 // always include format and model.
347 // Format is needed to deserialize, model is needed to interpret.
348 $vals['contentformat'] = $format;
349 $vals['contentmodel'] = $model;
350 }
351 }
352
353 if ( $text !== false ) {
354 ApiResult::setContentValue( $vals, 'content', $text );
355 }
356 }
357
358 if ( $content && ( !is_null( $this->diffto ) || !is_null( $this->difftotext ) ) ) {
359 static $n = 0; // Number of uncached diffs we've had
360
361 if ( $n < $this->getConfig()->get( 'APIMaxUncachedDiffs' ) ) {
362 $vals['diff'] = [];
363 $context = new DerivativeContext( $this->getContext() );
364 $context->setTitle( $title );
365 $handler = $revision->getContentHandler();
366
367 if ( !is_null( $this->difftotext ) ) {
368 $model = $title->getContentModel();
369
370 if ( $this->contentFormat
371 && !ContentHandler::getForModelID( $model )->isSupportedFormat( $this->contentFormat )
372 ) {
373 $name = $title->getPrefixedDBkey();
374 $this->setWarning( "The requested format {$this->contentFormat} is not " .
375 "supported for content model $model used by $name" );
376 $vals['diff']['badcontentformat'] = true;
377 $engine = null;
378 } else {
379 $difftocontent = ContentHandler::makeContent(
380 $this->difftotext,
381 $title,
382 $model,
383 $this->contentFormat
384 );
385
386 if ( $this->difftotextpst ) {
387 $popts = ParserOptions::newFromContext( $this->getContext() );
388 $difftocontent = $difftocontent->preSaveTransform( $title, $user, $popts );
389 }
390
391 $engine = $handler->createDifferenceEngine( $context );
392 $engine->setContent( $content, $difftocontent );
393 }
394 } else {
395 $engine = $handler->createDifferenceEngine( $context, $revision->getId(), $this->diffto );
396 $vals['diff']['from'] = $engine->getOldid();
397 $vals['diff']['to'] = $engine->getNewid();
398 }
399 if ( $engine ) {
400 $difftext = $engine->getDiffBody();
401 ApiResult::setContentValue( $vals['diff'], 'body', $difftext );
402 if ( !$engine->wasCacheHit() ) {
403 $n++;
404 }
405 }
406 } else {
407 $vals['diff']['notcached'] = true;
408 }
409 }
410
411 if ( $anyHidden && $revision->isDeleted( Revision::DELETED_RESTRICTED ) ) {
412 $vals['suppressed'] = true;
413 }
414
415 return $vals;
416 }
417
418 public function getCacheMode( $params ) {
419 if ( $this->userCanSeeRevDel() ) {
420 return 'private';
421 }
422
423 return 'public';
424 }
425
426 public function getAllowedParams() {
427 return [
428 'prop' => [
430 ApiBase::PARAM_DFLT => 'ids|timestamp|flags|comment|user',
432 'ids',
433 'flags',
434 'timestamp',
435 'user',
436 'userid',
437 'size',
438 'sha1',
439 'contentmodel',
440 'comment',
441 'parsedcomment',
442 'content',
443 'tags',
444 'parsetree',
445 ],
446 ApiBase::PARAM_HELP_MSG => 'apihelp-query+revisions+base-param-prop',
448 'ids' => 'apihelp-query+revisions+base-paramvalue-prop-ids',
449 'flags' => 'apihelp-query+revisions+base-paramvalue-prop-flags',
450 'timestamp' => 'apihelp-query+revisions+base-paramvalue-prop-timestamp',
451 'user' => 'apihelp-query+revisions+base-paramvalue-prop-user',
452 'userid' => 'apihelp-query+revisions+base-paramvalue-prop-userid',
453 'size' => 'apihelp-query+revisions+base-paramvalue-prop-size',
454 'sha1' => 'apihelp-query+revisions+base-paramvalue-prop-sha1',
455 'contentmodel' => 'apihelp-query+revisions+base-paramvalue-prop-contentmodel',
456 'comment' => 'apihelp-query+revisions+base-paramvalue-prop-comment',
457 'parsedcomment' => 'apihelp-query+revisions+base-paramvalue-prop-parsedcomment',
458 'content' => 'apihelp-query+revisions+base-paramvalue-prop-content',
459 'tags' => 'apihelp-query+revisions+base-paramvalue-prop-tags',
460 'parsetree' => [ 'apihelp-query+revisions+base-paramvalue-prop-parsetree',
462 ],
463 ],
464 'limit' => [
465 ApiBase::PARAM_TYPE => 'limit',
469 ApiBase::PARAM_HELP_MSG => 'apihelp-query+revisions+base-param-limit',
470 ],
471 'expandtemplates' => [
472 ApiBase::PARAM_DFLT => false,
473 ApiBase::PARAM_HELP_MSG => 'apihelp-query+revisions+base-param-expandtemplates',
474 ],
475 'generatexml' => [
476 ApiBase::PARAM_DFLT => false,
478 ApiBase::PARAM_HELP_MSG => 'apihelp-query+revisions+base-param-generatexml',
479 ],
480 'parse' => [
481 ApiBase::PARAM_DFLT => false,
482 ApiBase::PARAM_HELP_MSG => 'apihelp-query+revisions+base-param-parse',
483 ],
484 'section' => [
485 ApiBase::PARAM_HELP_MSG => 'apihelp-query+revisions+base-param-section',
486 ],
487 'diffto' => [
488 ApiBase::PARAM_HELP_MSG => 'apihelp-query+revisions+base-param-diffto',
489 ],
490 'difftotext' => [
491 ApiBase::PARAM_HELP_MSG => 'apihelp-query+revisions+base-param-difftotext',
492 ],
493 'difftotextpst' => [
494 ApiBase::PARAM_DFLT => false,
495 ApiBase::PARAM_HELP_MSG => 'apihelp-query+revisions+base-param-difftotextpst',
496 ],
497 'contentformat' => [
499 ApiBase::PARAM_HELP_MSG => 'apihelp-query+revisions+base-param-contentformat',
500 ],
501 ];
502 }
503
504}
wfTimestamp( $outputtype=TS_UNIX, $ts=0)
Get a timestamp string in one of various formats.
getContext()
$wgParser
Definition Setup.php:821
getModulePrefix()
Get parameter prefix (usually two letters or an empty string).
Definition ApiBase.php:472
const PARAM_MAX2
(integer) Max value allowed for the parameter for users with the apihighlimits right,...
Definition ApiBase.php:97
const PARAM_DEPRECATED
(boolean) Is the parameter deprecated (will show a warning)?
Definition ApiBase.php:106
const PARAM_MAX
(integer) Max value allowed for the parameter, for PARAM_TYPE 'integer' and 'limit'.
Definition ApiBase.php:91
getMain()
Get the main module.
Definition ApiBase.php:480
const PARAM_TYPE
(string|string[]) Either an array of allowed value strings, or a string type as described below.
Definition ApiBase.php:88
const PARAM_DFLT
(null|boolean|integer|string) Default value of the parameter.
Definition ApiBase.php:50
const PARAM_HELP_MSG_PER_VALUE
((string|array|Message)[]) When PARAM_TYPE is an array, this is an array mapping those values to $msg...
Definition ApiBase.php:157
dieUsageMsg( $error)
Output the error message related to a certain array.
Definition ApiBase.php:2203
setWarning( $warning)
Set warning section for this module.
Definition ApiBase.php:1554
const PARAM_MIN
(integer) Lowest value allowed for the parameter, for PARAM_TYPE 'integer' and 'limit'.
Definition ApiBase.php:100
const LIMIT_BIG1
Fast query, standard limit.
Definition ApiBase.php:184
const LIMIT_SML2
Slow query, apihighlimits limit.
Definition ApiBase.php:190
validateLimit( $paramName, &$value, $min, $max, $botMax=null, $enforceLimits=false)
Validate the value against the minimum and user/bot maximum limits.
Definition ApiBase.php:1296
getResult()
Get the result object.
Definition ApiBase.php:584
const LIMIT_SML1
Slow query, standard limit.
Definition ApiBase.php:188
const PARAM_HELP_MSG
(string|array|Message) Specify an alternative i18n documentation message for this parameter.
Definition ApiBase.php:125
const LIMIT_BIG2
Fast query, apihighlimits limit.
Definition ApiBase.php:186
getModuleName()
Get the name of the module being executed by this instance.
Definition ApiBase.php:464
dieUsage( $description, $errorCode, $httpRespCode=0, $extradata=null)
Throw a UsageException, which will (if uncaught) call the main module's error handler and die with an...
Definition ApiBase.php:1585
const PARAM_ISMULTI
(boolean) Accept multiple pipe-separated values for this parameter (e.g.
Definition ApiBase.php:53
This class contains a list of pages that the client has requested.
userCanSeeRevDel()
Check whether the current user has permission to view revision-deleted fields.
A base class for functions common to producing a list of revisions.
executeGenerator( $resultPageSet)
Execute this module as a generator.
getCacheMode( $params)
Get the cache mode for the data generated by this module.
parseParameters( $params)
Parse the parameters into the various instance fields.
getAllowedParams()
Returns an array of allowed parameters (parameter name) => (default value) or (parameter name) => (ar...
execute()
Evaluates the parameters, performs the requested query, and sets up the result.
extractRevisionInfo(Revision $revision, $row)
Extract information from the Revision.
run(ApiPageSet $resultPageSet=null)
static setIndexedTagName(array &$arr, $tag)
Set the tag name for numeric-keyed values in XML format.
static setContentValue(array &$arr, $name, $value, $flags=0)
Add an output value to the array by name and mark as META_CONTENT.
static getAllContentFormats()
static makeContent( $text, Title $title=null, $modelId=null, $format=null)
Convenience function for creating a Content object from a given textual representation.
static getForModelID( $modelId)
Returns the ContentHandler singleton for the given model ID.
getUser()
Get the User object.
getConfig()
Get the Config object.
IContextSource $context
An IContextSource implementation which will inherit context from another source but allow individual ...
static formatComment( $comment, $title=null, $local=false, $wikiId=null)
This function is called by all recent changes variants, by the page history, and by the user contribu...
Definition Linker.php:1180
static newFromContext(IContextSource $context)
Get a ParserOptions object from a IContextSource object.
getUserText( $audience=self::FOR_PUBLIC, User $user=null)
Fetch revision's username if it's available to the specified audience.
Definition Revision.php:897
getTitle()
Returns the title of the page associated with this entry or null.
Definition Revision.php:803
getSize()
Returns the length of the text in this revision, or null if unknown.
Definition Revision.php:783
getId()
Get revision ID.
Definition Revision.php:729
getContentHandler()
Returns the content handler appropriate for this revision's content model.
getComment( $audience=self::FOR_PUBLIC, User $user=null)
Fetch revision comment if it's available to the specified audience.
Definition Revision.php:941
getContentModel()
Returns the content model for this revision.
getUser( $audience=self::FOR_PUBLIC, User $user=null)
Fetch revision's user id if it's available to the specified audience.
Definition Revision.php:863
getContent( $audience=self::FOR_PUBLIC, User $user=null)
Fetch revision content if it's available to the specified audience.
const DELETED_USER
Definition Revision.php:87
const DELETED_TEXT
Definition Revision.php:85
getSha1()
Returns the base36 sha1 of the text in this revision, or null if unknown.
Definition Revision.php:792
const DELETED_RESTRICTED
Definition Revision.php:88
userCan( $field, User $user=null)
Determine if the current user is allowed to view a particular field of this revision,...
getParentId()
Get parent revision ID (the original previous page revision)
Definition Revision.php:774
const RAW
Definition Revision.php:94
isDeleted( $field)
const DELETED_COMMENT
Definition Revision.php:86
const FOR_THIS_USER
Definition Revision.php:93
static newFromId( $id, $flags=0)
Load a page revision from a given revision ID number.
Definition Revision.php:110
per default it will return the text for text based content
We use the convention $dbr for read and $dbw for write to help you keep track of whether the database object is a the world will explode Or to be a subsequent write query which succeeded on the master may fail when replicated to the slave due to a unique key collision Replication on the slave will stop and it may take hours to repair the database and get it back online Setting read_only in my cnf on the slave will avoid this but given the dire we prefer to have as many checks as possible We provide a but the wrapper functions like please read the documentation for except in special pages derived from QueryPage It s a common pitfall for new developers to submit code containing SQL queries which examine huge numbers of rows Remember that COUNT * is(N), counting rows in atable is like counting beans in a bucket.------------------------------------------------------------------------ Replication------------------------------------------------------------------------The largest installation of MediaWiki, Wikimedia, uses a large set ofslave MySQL servers replicating writes made to a master MySQL server. Itis important to understand the issues associated with this setup if youwant to write code destined for Wikipedia.It 's often the case that the best algorithm to use for a given taskdepends on whether or not replication is in use. Due to our unabashedWikipedia-centrism, we often just use the replication-friendly version, but if you like, you can use wfGetLB() ->getServerCount() > 1 tocheck to see if replication is in use.===Lag===Lag primarily occurs when large write queries are sent to the master.Writes on the master are executed in parallel, but they are executed inserial when they are replicated to the slaves. The master writes thequery to the binlog when the transaction is committed. The slaves pollthe binlog and start executing the query as soon as it appears. They canservice reads while they are performing a write query, but will not readanything more from the binlog and thus will perform no more writes. Thismeans that if the write query runs for a long time, the slaves will lagbehind the master for the time it takes for the write query to complete.Lag can be exacerbated by high read load. MediaWiki 's load balancer willstop sending reads to a slave when it is lagged by more than 30 seconds.If the load ratios are set incorrectly, or if there is too much loadgenerally, this may lead to a slave permanently hovering around 30seconds lag.If all slaves are lagged by more than 30 seconds, MediaWiki will stopwriting to the database. All edits and other write operations will berefused, with an error returned to the user. This gives the slaves achance to catch up. Before we had this mechanism, the slaves wouldregularly lag by several minutes, making review of recent editsdifficult.In addition to this, MediaWiki attempts to ensure that the user seesevents occurring on the wiki in chronological order. A few seconds of lagcan be tolerated, as long as the user sees a consistent picture fromsubsequent requests. This is done by saving the master binlog positionin the session, and then at the start of each request, waiting for theslave to catch up to that position before doing any reads from it. Ifthis wait times out, reads are allowed anyway, but the request isconsidered to be in "lagged slave mode". Lagged slave mode can bechecked by calling wfGetLB() ->getLaggedSlaveMode(). The onlypractical consequence at present is a warning displayed in the pagefooter.===Lag avoidance===To avoid excessive lag, queries which write large numbers of rows shouldbe split up, generally to write one row at a time. Multi-row INSERT ...SELECT queries are the worst offenders should be avoided altogether.Instead do the select first and then the insert.===Working with lag===Despite our best efforts, it 's not practical to guarantee a low-lagenvironment. Lag will usually be less than one second, but mayoccasionally be up to 30 seconds. For scalability, it 's very importantto keep load on the master low, so simply sending all your queries tothe master is not the answer. So when you have a genuine need forup-to-date data, the following approach is advised:1) Do a quick query to the master for a sequence number or timestamp 2) Run the full query on the slave and check if it matches the data you gotfrom the master 3) If it doesn 't, run the full query on the masterTo avoid swamping the master every time the slaves lag, use of thisapproach should be kept to a minimum. In most cases you should just readfrom the slave and let the user deal with the delay.------------------------------------------------------------------------ Lock contention------------------------------------------------------------------------Due to the high write rate on Wikipedia(and some other wikis), MediaWiki developers need to be very careful to structure their writesto avoid long-lasting locks. By default, MediaWiki opens a transactionat the first query, and commits it before the output is sent. Locks willbe held from the time when the query is done until the commit. So youcan reduce lock time by doing as much processing as possible before youdo your write queries.Often this approach is not good enough, and it becomes necessary toenclose small groups of queries in their own transaction. Use thefollowing syntax:$dbw=wfGetDB(DB_MASTER
when a variable name is used in a it is silently declared as a new local masking the global
Definition design.txt:95
const CONTENT_MODEL_WIKITEXT
Definition Defines.php:239
please add to it if you re going to add events to the MediaWiki code where normally authentication against an external auth plugin would be creating a local account $user
Definition hooks.txt:249
namespace and then decline to actually register it file or subcat img or subcat $title
Definition hooks.txt:986
this hook is for auditing only RecentChangesLinked and Watchlist RecentChangesLinked and Watchlist e g Watchlist removed from all revisions and log entries to which it was applied This gives extensions a chance to take it off their books as the deletion has already been partly carried out by this point or something similar the user will be unable to create the tag set and then return false from the hook function Ensure you consume the ChangeTagAfterDelete hook to carry out custom deletion actions as context called by AbstractContent::getParserOutput May be used to override the normal model specific rendering of page content $content
Definition hooks.txt:1094
the value to return A Title object or null for latest all implement SearchIndexField $engine
Definition hooks.txt:2755
Allows to change the fields on the form that will be generated $name
Definition hooks.txt:304
this hook is for auditing only or null if authentication failed before getting that far or null if we can t even determine that probably a stub it is not rendered in wiki pages or galleries in category pages allow injecting custom HTML after the section Any uses of the hook need to handle escaping see BaseTemplate::getToolbox and BaseTemplate::makeListItem for details on the format of individual items inside of this array or by returning and letting standard HTTP rendering take place modifiable or by returning false and taking over the output modifiable modifiable after all normalizations have been except for the $wgMaxImageArea check set to true or false to override the $wgMaxImageArea check result gives extension the possibility to transform it themselves $handler
Definition hooks.txt:925
$comment
injection txt This is an overview of how MediaWiki makes use of dependency injection The design described here grew from the discussion of RFC T384 The term dependency this means that anything an object needs to operate should be injected from the the object itself should only know narrow no concrete implementation of the logic it relies on The requirement to inject everything typically results in an architecture that based on two main types of and essentially stateless service objects that use other service objects to operate on the value objects As of the beginning MediaWiki is only starting to use the DI approach Much of the code still relies on global state or direct resulting in a highly cyclical dependency which acts as the top level factory for services in MediaWiki which can be used to gain access to default instances of various services MediaWikiServices however also allows new services to be defined and default services to be redefined Services are defined or redefined by providing a callback the instantiator that will return a new instance of the service When it will create an instance of MediaWikiServices and populate it with the services defined in the files listed by thereby bootstrapping the DI framework Per $wgServiceWiringFiles lists includes ServiceWiring php
Definition injection.txt:37
!article Main Page !text blah blah !endarticle !article Foo !text FOO !endarticle !article Template
$params
const TS_ISO_8601
ISO 8601 format with no timezone: 1986-02-09T20:00:00Z.
Definition defines.php:28