MediaWiki  1.28.0
JobQueueRedis.php
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1 <?php
24 
67 class JobQueueRedis extends JobQueue {
69  protected $redisPool;
71  protected $logger;
72 
74  protected $server;
76  protected $compression;
77 
91  public function __construct( array $params ) {
92  parent::__construct( $params );
93  $params['redisConfig']['serializer'] = 'none'; // make it easy to use Lua
94  $this->server = $params['redisServer'];
95  $this->compression = isset( $params['compression'] ) ? $params['compression'] : 'none';
96  $this->redisPool = RedisConnectionPool::singleton( $params['redisConfig'] );
97  if ( empty( $params['daemonized'] ) ) {
98  throw new InvalidArgumentException(
99  "Non-daemonized mode is no longer supported. Please install the " .
100  "mediawiki/services/jobrunner service and update \$wgJobTypeConf as needed." );
101  }
102  $this->logger = \MediaWiki\Logger\LoggerFactory::getInstance( 'redis' );
103  }
104 
105  protected function supportedOrders() {
106  return [ 'timestamp', 'fifo' ];
107  }
108 
109  protected function optimalOrder() {
110  return 'fifo';
111  }
112 
113  protected function supportsDelayedJobs() {
114  return true;
115  }
116 
122  protected function doIsEmpty() {
123  return $this->doGetSize() == 0;
124  }
125 
131  protected function doGetSize() {
132  $conn = $this->getConnection();
133  try {
134  return $conn->lSize( $this->getQueueKey( 'l-unclaimed' ) );
135  } catch ( RedisException $e ) {
136  $this->throwRedisException( $conn, $e );
137  }
138  }
139 
145  protected function doGetAcquiredCount() {
146  $conn = $this->getConnection();
147  try {
148  $conn->multi( Redis::PIPELINE );
149  $conn->zSize( $this->getQueueKey( 'z-claimed' ) );
150  $conn->zSize( $this->getQueueKey( 'z-abandoned' ) );
151 
152  return array_sum( $conn->exec() );
153  } catch ( RedisException $e ) {
154  $this->throwRedisException( $conn, $e );
155  }
156  }
157 
163  protected function doGetDelayedCount() {
164  $conn = $this->getConnection();
165  try {
166  return $conn->zSize( $this->getQueueKey( 'z-delayed' ) );
167  } catch ( RedisException $e ) {
168  $this->throwRedisException( $conn, $e );
169  }
170  }
171 
177  protected function doGetAbandonedCount() {
178  $conn = $this->getConnection();
179  try {
180  return $conn->zSize( $this->getQueueKey( 'z-abandoned' ) );
181  } catch ( RedisException $e ) {
182  $this->throwRedisException( $conn, $e );
183  }
184  }
185 
193  protected function doBatchPush( array $jobs, $flags ) {
194  // Convert the jobs into field maps (de-duplicated against each other)
195  $items = []; // (job ID => job fields map)
196  foreach ( $jobs as $job ) {
197  $item = $this->getNewJobFields( $job );
198  if ( strlen( $item['sha1'] ) ) { // hash identifier => de-duplicate
199  $items[$item['sha1']] = $item;
200  } else {
201  $items[$item['uuid']] = $item;
202  }
203  }
204 
205  if ( !count( $items ) ) {
206  return; // nothing to do
207  }
208 
209  $conn = $this->getConnection();
210  try {
211  // Actually push the non-duplicate jobs into the queue...
212  if ( $flags & self::QOS_ATOMIC ) {
213  $batches = [ $items ]; // all or nothing
214  } else {
215  $batches = array_chunk( $items, 100 ); // avoid tying up the server
216  }
217  $failed = 0;
218  $pushed = 0;
219  foreach ( $batches as $itemBatch ) {
220  $added = $this->pushBlobs( $conn, $itemBatch );
221  if ( is_int( $added ) ) {
222  $pushed += $added;
223  } else {
224  $failed += count( $itemBatch );
225  }
226  }
227  JobQueue::incrStats( 'inserts', $this->type, count( $items ) );
228  JobQueue::incrStats( 'inserts_actual', $this->type, $pushed );
229  JobQueue::incrStats( 'dupe_inserts', $this->type,
230  count( $items ) - $failed - $pushed );
231  if ( $failed > 0 ) {
232  $err = "Could not insert {$failed} {$this->type} job(s).";
233  wfDebugLog( 'JobQueueRedis', $err );
234  throw new RedisException( $err );
235  }
236  } catch ( RedisException $e ) {
237  $this->throwRedisException( $conn, $e );
238  }
239  }
240 
247  protected function pushBlobs( RedisConnRef $conn, array $items ) {
248  $args = [ $this->encodeQueueName() ];
249  // Next args come in 4s ([id, sha1, rtime, blob [, id, sha1, rtime, blob ... ] ] )
250  foreach ( $items as $item ) {
251  $args[] = (string)$item['uuid'];
252  $args[] = (string)$item['sha1'];
253  $args[] = (string)$item['rtimestamp'];
254  $args[] = (string)$this->serialize( $item );
255  }
256  static $script =
258 <<<LUA
259  local kUnclaimed, kSha1ById, kIdBySha1, kDelayed, kData, kQwJobs = unpack(KEYS)
260  -- First argument is the queue ID
261  local queueId = ARGV[1]
262  -- Next arguments all come in 4s (one per job)
263  local variadicArgCount = #ARGV - 1
264  if variadicArgCount % 4 ~= 0 then
265  return redis.error_reply('Unmatched arguments')
266  end
267  -- Insert each job into this queue as needed
268  local pushed = 0
269  for i = 2,#ARGV,4 do
270  local id,sha1,rtimestamp,blob = ARGV[i],ARGV[i+1],ARGV[i+2],ARGV[i+3]
271  if sha1 == '' or redis.call('hExists',kIdBySha1,sha1) == 0 then
272  if 1*rtimestamp > 0 then
273  -- Insert into delayed queue (release time as score)
274  redis.call('zAdd',kDelayed,rtimestamp,id)
275  else
276  -- Insert into unclaimed queue
277  redis.call('lPush',kUnclaimed,id)
278  end
279  if sha1 ~= '' then
280  redis.call('hSet',kSha1ById,id,sha1)
281  redis.call('hSet',kIdBySha1,sha1,id)
282  end
283  redis.call('hSet',kData,id,blob)
284  pushed = pushed + 1
285  end
286  end
287  -- Mark this queue as having jobs
288  redis.call('sAdd',kQwJobs,queueId)
289  return pushed
290 LUA;
291  return $conn->luaEval( $script,
292  array_merge(
293  [
294  $this->getQueueKey( 'l-unclaimed' ), # KEYS[1]
295  $this->getQueueKey( 'h-sha1ById' ), # KEYS[2]
296  $this->getQueueKey( 'h-idBySha1' ), # KEYS[3]
297  $this->getQueueKey( 'z-delayed' ), # KEYS[4]
298  $this->getQueueKey( 'h-data' ), # KEYS[5]
299  $this->getGlobalKey( 's-queuesWithJobs' ), # KEYS[6]
300  ],
301  $args
302  ),
303  6 # number of first argument(s) that are keys
304  );
305  }
306 
312  protected function doPop() {
313  $job = false;
314 
315  $conn = $this->getConnection();
316  try {
317  do {
318  $blob = $this->popAndAcquireBlob( $conn );
319  if ( !is_string( $blob ) ) {
320  break; // no jobs; nothing to do
321  }
322 
323  JobQueue::incrStats( 'pops', $this->type );
324  $item = $this->unserialize( $blob );
325  if ( $item === false ) {
326  wfDebugLog( 'JobQueueRedis', "Could not unserialize {$this->type} job." );
327  continue;
328  }
329 
330  // If $item is invalid, the runner loop recyling will cleanup as needed
331  $job = $this->getJobFromFields( $item ); // may be false
332  } while ( !$job ); // job may be false if invalid
333  } catch ( RedisException $e ) {
334  $this->throwRedisException( $conn, $e );
335  }
336 
337  return $job;
338  }
339 
345  protected function popAndAcquireBlob( RedisConnRef $conn ) {
346  static $script =
348 <<<LUA
349  local kUnclaimed, kSha1ById, kIdBySha1, kClaimed, kAttempts, kData = unpack(KEYS)
350  local rTime = unpack(ARGV)
351  -- Pop an item off the queue
352  local id = redis.call('rPop',kUnclaimed)
353  if not id then
354  return false
355  end
356  -- Allow new duplicates of this job
357  local sha1 = redis.call('hGet',kSha1ById,id)
358  if sha1 then redis.call('hDel',kIdBySha1,sha1) end
359  redis.call('hDel',kSha1ById,id)
360  -- Mark the jobs as claimed and return it
361  redis.call('zAdd',kClaimed,rTime,id)
362  redis.call('hIncrBy',kAttempts,id,1)
363  return redis.call('hGet',kData,id)
364 LUA;
365  return $conn->luaEval( $script,
366  [
367  $this->getQueueKey( 'l-unclaimed' ), # KEYS[1]
368  $this->getQueueKey( 'h-sha1ById' ), # KEYS[2]
369  $this->getQueueKey( 'h-idBySha1' ), # KEYS[3]
370  $this->getQueueKey( 'z-claimed' ), # KEYS[4]
371  $this->getQueueKey( 'h-attempts' ), # KEYS[5]
372  $this->getQueueKey( 'h-data' ), # KEYS[6]
373  time(), # ARGV[1] (injected to be replication-safe)
374  ],
375  6 # number of first argument(s) that are keys
376  );
377  }
378 
386  protected function doAck( Job $job ) {
387  if ( !isset( $job->metadata['uuid'] ) ) {
388  throw new UnexpectedValueException( "Job of type '{$job->getType()}' has no UUID." );
389  }
390 
391  $uuid = $job->metadata['uuid'];
392  $conn = $this->getConnection();
393  try {
394  static $script =
396 <<<LUA
397  local kClaimed, kAttempts, kData = unpack(KEYS)
398  local id = unpack(ARGV)
399  -- Unmark the job as claimed
400  local removed = redis.call('zRem',kClaimed,id)
401  -- Check if the job was recycled
402  if removed == 0 then
403  return 0
404  end
405  -- Delete the retry data
406  redis.call('hDel',kAttempts,id)
407  -- Delete the job data itself
408  return redis.call('hDel',kData,id)
409 LUA;
410  $res = $conn->luaEval( $script,
411  [
412  $this->getQueueKey( 'z-claimed' ), # KEYS[1]
413  $this->getQueueKey( 'h-attempts' ), # KEYS[2]
414  $this->getQueueKey( 'h-data' ), # KEYS[3]
415  $uuid # ARGV[1]
416  ],
417  3 # number of first argument(s) that are keys
418  );
419 
420  if ( !$res ) {
421  wfDebugLog( 'JobQueueRedis', "Could not acknowledge {$this->type} job $uuid." );
422 
423  return false;
424  }
425 
426  JobQueue::incrStats( 'acks', $this->type );
427  } catch ( RedisException $e ) {
428  $this->throwRedisException( $conn, $e );
429  }
430 
431  return true;
432  }
433 
442  if ( !$job->hasRootJobParams() ) {
443  throw new LogicException( "Cannot register root job; missing parameters." );
444  }
445  $params = $job->getRootJobParams();
446 
447  $key = $this->getRootJobCacheKey( $params['rootJobSignature'] );
448 
449  $conn = $this->getConnection();
450  try {
451  $timestamp = $conn->get( $key ); // current last timestamp of this job
452  if ( $timestamp && $timestamp >= $params['rootJobTimestamp'] ) {
453  return true; // a newer version of this root job was enqueued
454  }
455 
456  // Update the timestamp of the last root job started at the location...
457  return $conn->set( $key, $params['rootJobTimestamp'], self::ROOTJOB_TTL ); // 2 weeks
458  } catch ( RedisException $e ) {
459  $this->throwRedisException( $conn, $e );
460  }
461  }
462 
469  protected function doIsRootJobOldDuplicate( Job $job ) {
470  if ( !$job->hasRootJobParams() ) {
471  return false; // job has no de-deplication info
472  }
473  $params = $job->getRootJobParams();
474 
475  $conn = $this->getConnection();
476  try {
477  // Get the last time this root job was enqueued
478  $timestamp = $conn->get( $this->getRootJobCacheKey( $params['rootJobSignature'] ) );
479  } catch ( RedisException $e ) {
480  $timestamp = false;
481  $this->throwRedisException( $conn, $e );
482  }
483 
484  // Check if a new root job was started at the location after this one's...
485  return ( $timestamp && $timestamp > $params['rootJobTimestamp'] );
486  }
487 
493  protected function doDelete() {
494  static $props = [ 'l-unclaimed', 'z-claimed', 'z-abandoned',
495  'z-delayed', 'h-idBySha1', 'h-sha1ById', 'h-attempts', 'h-data' ];
496 
497  $conn = $this->getConnection();
498  try {
499  $keys = [];
500  foreach ( $props as $prop ) {
501  $keys[] = $this->getQueueKey( $prop );
502  }
503 
504  $ok = ( $conn->delete( $keys ) !== false );
505  $conn->sRem( $this->getGlobalKey( 's-queuesWithJobs' ), $this->encodeQueueName() );
506 
507  return $ok;
508  } catch ( RedisException $e ) {
509  $this->throwRedisException( $conn, $e );
510  }
511  }
512 
518  public function getAllQueuedJobs() {
519  $conn = $this->getConnection();
520  try {
521  $uids = $conn->lRange( $this->getQueueKey( 'l-unclaimed' ), 0, -1 );
522  } catch ( RedisException $e ) {
523  $this->throwRedisException( $conn, $e );
524  }
525 
526  return $this->getJobIterator( $conn, $uids );
527  }
528 
534  public function getAllDelayedJobs() {
535  $conn = $this->getConnection();
536  try {
537  $uids = $conn->zRange( $this->getQueueKey( 'z-delayed' ), 0, -1 );
538  } catch ( RedisException $e ) {
539  $this->throwRedisException( $conn, $e );
540  }
541 
542  return $this->getJobIterator( $conn, $uids );
543  }
544 
550  public function getAllAcquiredJobs() {
551  $conn = $this->getConnection();
552  try {
553  $uids = $conn->zRange( $this->getQueueKey( 'z-claimed' ), 0, -1 );
554  } catch ( RedisException $e ) {
555  $this->throwRedisException( $conn, $e );
556  }
557 
558  return $this->getJobIterator( $conn, $uids );
559  }
560 
566  public function getAllAbandonedJobs() {
567  $conn = $this->getConnection();
568  try {
569  $uids = $conn->zRange( $this->getQueueKey( 'z-abandoned' ), 0, -1 );
570  } catch ( RedisException $e ) {
571  $this->throwRedisException( $conn, $e );
572  }
573 
574  return $this->getJobIterator( $conn, $uids );
575  }
576 
582  protected function getJobIterator( RedisConnRef $conn, array $uids ) {
583  return new MappedIterator(
584  $uids,
585  function ( $uid ) use ( $conn ) {
586  return $this->getJobFromUidInternal( $uid, $conn );
587  },
588  [ 'accept' => function ( $job ) {
589  return is_object( $job );
590  } ]
591  );
592  }
593 
594  public function getCoalesceLocationInternal() {
595  return "RedisServer:" . $this->server;
596  }
597 
598  protected function doGetSiblingQueuesWithJobs( array $types ) {
599  return array_keys( array_filter( $this->doGetSiblingQueueSizes( $types ) ) );
600  }
601 
602  protected function doGetSiblingQueueSizes( array $types ) {
603  $sizes = []; // (type => size)
604  $types = array_values( $types ); // reindex
605  $conn = $this->getConnection();
606  try {
607  $conn->multi( Redis::PIPELINE );
608  foreach ( $types as $type ) {
609  $conn->lSize( $this->getQueueKey( 'l-unclaimed', $type ) );
610  }
611  $res = $conn->exec();
612  if ( is_array( $res ) ) {
613  foreach ( $res as $i => $size ) {
614  $sizes[$types[$i]] = $size;
615  }
616  }
617  } catch ( RedisException $e ) {
618  $this->throwRedisException( $conn, $e );
619  }
620 
621  return $sizes;
622  }
623 
633  public function getJobFromUidInternal( $uid, RedisConnRef $conn ) {
634  try {
635  $data = $conn->hGet( $this->getQueueKey( 'h-data' ), $uid );
636  if ( $data === false ) {
637  return false; // not found
638  }
639  $item = $this->unserialize( $data );
640  if ( !is_array( $item ) ) { // this shouldn't happen
641  throw new UnexpectedValueException( "Could not find job with ID '$uid'." );
642  }
643  $title = Title::makeTitle( $item['namespace'], $item['title'] );
644  $job = Job::factory( $item['type'], $title, $item['params'] );
645  $job->metadata['uuid'] = $item['uuid'];
646  $job->metadata['timestamp'] = $item['timestamp'];
647  // Add in attempt count for debugging at showJobs.php
648  $job->metadata['attempts'] = $conn->hGet( $this->getQueueKey( 'h-attempts' ), $uid );
649 
650  return $job;
651  } catch ( RedisException $e ) {
652  $this->throwRedisException( $conn, $e );
653  }
654  }
655 
661  public function getServerQueuesWithJobs() {
662  $queues = [];
663 
664  $conn = $this->getConnection();
665  try {
666  $set = $conn->sMembers( $this->getGlobalKey( 's-queuesWithJobs' ) );
667  foreach ( $set as $queue ) {
668  $queues[] = $this->decodeQueueName( $queue );
669  }
670  } catch ( RedisException $e ) {
671  $this->throwRedisException( $conn, $e );
672  }
673 
674  return $queues;
675  }
676 
681  protected function getNewJobFields( IJobSpecification $job ) {
682  return [
683  // Fields that describe the nature of the job
684  'type' => $job->getType(),
685  'namespace' => $job->getTitle()->getNamespace(),
686  'title' => $job->getTitle()->getDBkey(),
687  'params' => $job->getParams(),
688  // Some jobs cannot run until a "release timestamp"
689  'rtimestamp' => $job->getReleaseTimestamp() ?: 0,
690  // Additional job metadata
692  'sha1' => $job->ignoreDuplicates()
693  ? Wikimedia\base_convert( sha1( serialize( $job->getDeduplicationInfo() ) ), 16, 36, 31 )
694  : '',
695  'timestamp' => time() // UNIX timestamp
696  ];
697  }
698 
703  protected function getJobFromFields( array $fields ) {
704  $title = Title::makeTitle( $fields['namespace'], $fields['title'] );
705  $job = Job::factory( $fields['type'], $title, $fields['params'] );
706  $job->metadata['uuid'] = $fields['uuid'];
707  $job->metadata['timestamp'] = $fields['timestamp'];
708 
709  return $job;
710  }
711 
716  protected function serialize( array $fields ) {
717  $blob = serialize( $fields );
718  if ( $this->compression === 'gzip'
719  && strlen( $blob ) >= 1024
720  && function_exists( 'gzdeflate' )
721  ) {
722  $object = (object)[ 'blob' => gzdeflate( $blob ), 'enc' => 'gzip' ];
723  $blobz = serialize( $object );
724 
725  return ( strlen( $blobz ) < strlen( $blob ) ) ? $blobz : $blob;
726  } else {
727  return $blob;
728  }
729  }
730 
735  protected function unserialize( $blob ) {
736  $fields = unserialize( $blob );
737  if ( is_object( $fields ) ) {
738  if ( $fields->enc === 'gzip' && function_exists( 'gzinflate' ) ) {
739  $fields = unserialize( gzinflate( $fields->blob ) );
740  } else {
741  $fields = false;
742  }
743  }
744 
745  return is_array( $fields ) ? $fields : false;
746  }
747 
754  protected function getConnection() {
755  $conn = $this->redisPool->getConnection( $this->server, $this->logger );
756  if ( !$conn ) {
757  throw new JobQueueConnectionError(
758  "Unable to connect to redis server {$this->server}." );
759  }
760 
761  return $conn;
762  }
763 
769  protected function throwRedisException( RedisConnRef $conn, $e ) {
770  $this->redisPool->handleError( $conn, $e );
771  throw new JobQueueError( "Redis server error: {$e->getMessage()}\n" );
772  }
773 
777  private function encodeQueueName() {
778  return json_encode( [ $this->type, $this->wiki ] );
779  }
780 
785  private function decodeQueueName( $name ) {
786  return json_decode( $name );
787  }
788 
793  private function getGlobalKey( $name ) {
794  $parts = [ 'global', 'jobqueue', $name ];
795  foreach ( $parts as $part ) {
796  if ( !preg_match( '/[a-zA-Z0-9_-]+/', $part ) ) {
797  throw new InvalidArgumentException( "Key part characters are out of range." );
798  }
799  }
800 
801  return implode( ':', $parts );
802  }
803 
809  private function getQueueKey( $prop, $type = null ) {
810  $type = is_string( $type ) ? $type : $this->type;
811  list( $db, $prefix ) = wfSplitWikiID( $this->wiki );
812  $keyspace = $prefix ? "$db-$prefix" : $db;
813 
814  $parts = [ $keyspace, 'jobqueue', $type, $prop ];
815 
816  // Parts are typically ASCII, but encode for sanity to escape ":"
817  return implode( ':', array_map( 'rawurlencode', $parts ) );
818  }
819 }
Class to handle job queues stored in Redis.
luaEval($script, array $params, $numKeys)
pushBlobs(RedisConnRef $conn, array $items)
#define the
table suitable for use with IDatabase::select()
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Definition: deferred.txt:11
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Definition: hooks.txt:6
static incrStats($key, $type, $delta=1)
Call wfIncrStats() for the queue overall and for the queue type.
Definition: JobQueue.php:709
doAck(Job $job)
deferred txt A few of the database updates required by various functions here can be deferred until after the result page is displayed to the user For updating the view updating the linked to tables after a etc PHP does not yet have any way to tell the server to actually return and disconnect while still running these but it might have such a feature in the future We handle these by creating a deferred update object and putting those objects on a global list
Definition: deferred.txt:11
the array() calling protocol came about after MediaWiki 1.4rc1.
hasRootJobParams()
Definition: Job.php:290
getJobIterator(RedisConnRef $conn, array $uids)
getQueueKey($prop, $type=null)
processing should stop and the error should be shown to the user * false
Definition: hooks.txt:189
throwRedisException(RedisConnRef $conn, $e)
Apache License January AND DISTRIBUTION Definitions License shall mean the terms and conditions for use
string $compression
Compression method to use.
div flags Integer display flags(NO_ACTION_LINK, NO_EXTRA_USER_LINKS) 'LogException'returning false will NOT prevent logging $e
Definition: hooks.txt:2102
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
globals txt Globals are evil The original MediaWiki code relied on globals for processing context far too often MediaWiki development since then has been a story of slowly moving context out of global variables and into objects Storing processing context in object member variables allows those objects to be reused in a much more flexible way Consider the elegance of
database rows
Definition: globals.txt:10
static getInstance($channel)
Get a named logger instance from the currently configured logger factory.
RedisConnectionPool $redisPool
null for the local wiki Added in
Definition: hooks.txt:1555
Class to both describe a background job and handle jobs.
Definition: Job.php:31
This code would result in ircNotify being run twice when an article is and once for brion Hooks can return three possible true was required This is the default since MediaWiki *some string
Definition: hooks.txt:177
The First
Definition: primes.txt:1
it s the revision text itself In either if gzip is the revision text is gzipped $flags
Definition: hooks.txt:2703
globals will be eliminated from MediaWiki replaced by an application object which would be passed to constructors Whether that would be an convenient solution remains to be but certainly PHP makes such object oriented programming models easier than they were in previous versions For the time being MediaWiki programmers will have to work in an environment with some global context At the time of globals were initialised on startup by MediaWiki of these were configuration which are documented in DefaultSettings php There is no comprehensive documentation for the remaining however some of the most important ones are listed below They are typically initialised either in index php or in Setup php For a description of the see design txt $wgTitle Title object created from the request URL $wgOut OutputPage object for HTTP response $wgUser User object for the user associated with the current request $wgLang Language object selected by user preferences $wgContLang Language object associated with the wiki being viewed $wgParser Parser object Parser extensions register their hooks here $wgRequest WebRequest object
Definition: globals.txt:25
doGetSiblingQueueSizes(array $types)
Prior to maintenance scripts were a hodgepodge of code that had no cohesion or formal method of action Beginning maintenance scripts have been cleaned up to use a unified class Directory structure How to run a script How to write your own DIRECTORY STRUCTURE The maintenance directory of a MediaWiki installation contains several all of which have unique purposes HOW TO RUN A SCRIPT Ridiculously just call php someScript php that s in the top level maintenance directory if not default wiki
Definition: maintenance.txt:1
if($line===false) $args
Definition: cdb.php:64
The ContentHandler facility adds support for arbitrary content types on wiki instead of relying on wikitext for everything It was introduced in MediaWiki Each kind of and so on Built in content types are
serialize(array $fields)
static singleton(array $options)
decodeQueueName($name)
string $type
Job type.
Definition: JobQueue.php:35
getNewJobFields(IJobSpecification $job)
wfDebugLog($logGroup, $text, $dest= 'all', array $context=[])
Send a line to a supplementary debug log file, if configured, or main debug log if not...
getRootJobCacheKey($signature)
Definition: JobQueue.php:528
doDeduplicateRootJob(IJobSpecification $job)
static newRawUUIDv4($flags=0)
Return an RFC4122 compliant v4 UUID.
if($limit) $timestamp
doIsRootJobOldDuplicate(Job $job)
getRootJobParams()
Definition: Job.php:274
$res
Definition: database.txt:21
getDeduplicationInfo()
Subclasses may need to override this to make duplication detection work.
string $server
Server address.
$params
popAndAcquireBlob(RedisConnRef $conn)
and(b) You must cause any modified files to carry prominent notices stating that You changed the files
getJobFromUidInternal($uid, RedisConnRef $conn)
This function should not be called outside JobQueueRedis.
namespace and then decline to actually register it file or subcat img or subcat $title
Definition: hooks.txt:953
Convenience class for generating iterators from iterators.
This document is intended to provide useful advice for parties seeking to redistribute MediaWiki to end users It s targeted particularly at maintainers for Linux since it s been observed that distribution packages of MediaWiki often break We ve consistently had to recommend that users seeking support use official tarballs instead of their distribution s and this often solves whatever problem the user is having It would be nice if this could such as
Definition: distributors.txt:9
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 as context as context the output can only depend on parameters provided to this hook not on global state indicating whether full HTML should be generated If generation of HTML may be but other information should still be present in the ParserOutput object to manipulate or replace but no entry for that model exists in $wgContentHandlers if desired whether it is OK to use $contentModel on $title Handler functions that modify $ok should generally return false to prevent further hooks from further modifying $ok inclusive false for true for descending in case the handler function wants to provide a converted Content object Note that $result getContentModel() must return $toModel. 'CustomEditor'$rcid is used in generating this variable which contains information about the new such as the revision s whether the revision was marked as a minor edit or not
Definition: hooks.txt:1156
__construct(array $params)
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 $wgServiceWiringFiles lists includes ServiceWiring php
Definition: injection.txt:35
This document describes the state of Postgres support in and is fairly well maintained The main code is very well while extensions are very hit and miss it is probably the most supported database after MySQL Much of the work in making MediaWiki database agnostic came about through the work of creating Postgres as and are nearing end of but without copying over all the usage comments General notes on the but these can almost always be programmed around *Although Postgres has a true BOOLEAN type
Definition: postgres.txt:22
static factory($command, Title $title, $params=[])
Create the appropriate object to handle a specific job.
Definition: Job.php:68
Class to handle enqueueing and running of background jobs.
Definition: JobQueue.php:31
if(count($args)< 1) $job
skin txt MediaWiki includes four core it has been set as the default in MediaWiki since the replacing Monobook it had been the default skin since before being replaced by Vector largely rewritten in while keeping its appearance Several legacy skins were removed in the release
Definition: skin.txt:10
doGetSiblingQueuesWithJobs(array $types)
getJobFromFields(array $fields)
Helper class to handle automatically marking connectons as reusable (via RAII pattern) ...
Job queue task description interface.
This document is intended to provide useful advice for parties seeking to redistribute MediaWiki to end users It s targeted particularly at maintainers for Linux since it s been observed that distribution packages of MediaWiki often break We ve consistently had to recommend that users seeking support use official tarballs instead of their distribution s and this often solves whatever problem the user is having It would be nice if this could such and we might be restricted by PHP settings such as safe mode or open_basedir We cannot assume that the software even has read access anywhere useful Many shared hosts run all users web applications under the same so they can t rely on Unix and must forbid reads to even standard directories like tmp lest users read each others files We cannot assume that the user has the ability to install or run any programs not written as web accessible PHP scripts Since anything that works on cheap shared hosting will work if you have shell or root access MediaWiki s design is based around catering to the lowest common denominator Although we support higher end setups as the way many things work by default is tailored toward shared hosting These defaults are unconventional from the point of view of and they certainly aren t ideal for someone who s installing MediaWiki as MediaWiki does not conform to normal Unix filesystem layout Hopefully we ll offer direct support for standard layouts in the but for now *any change to the location of files is unsupported *Moving things and leaving symlinks will *probably *not break but it is *strongly *advised not to try any more intrusive changes to get MediaWiki to conform more closely to your filesystem hierarchy Any such attempt will almost certainly result in unnecessary bugs The standard recommended location to install relative to the web is it should be possible to enable the appropriate rewrite rules by if you can reconfigure the web server
getConnection()
Get a connection to the server that handles all sub-queues for this queue.
this class mediates it Skin Encapsulates a look and feel for the wiki All of the functions that render HTML and make choices about how to render it are here and are called from various other places when needed(most notably, OutputPage::addWikiText()).The StandardSkin object is a complete implementation
font id
wfSplitWikiID($wiki)
Split a wiki ID into DB name and table prefix.
=Architecture==Two class hierarchies are used to provide the functionality associated with the different content models:*Content interface(and AbstractContent base class) define functionality that acts on the concrete content of a page, and *ContentHandler base class provides functionality specific to a content model, but not acting on concrete content.The most important function of ContentHandler is to act as a factory for the appropriate implementation of Content.These Content objects are to be used by MediaWiki everywhere, instead of passing page content around as text.All manipulation and analysis of page content must be done via the appropriate methods of the Content object.For each content model, a subclass of ContentHandler has to be registered with $wgContentHandlers.The ContentHandler object for a given content model can be obtained using ContentHandler::getForModelID($id).Also Title, WikiPage and Revision now have getContentHandler() methods for convenience.ContentHandler objects are singletons that provide functionality specific to the content type, but not directly acting on the content of some page.ContentHandler::makeEmptyContent() and ContentHandler::unserializeContent() can be used to create a Content object of the appropriate type.However, it is recommended to instead use WikiPage::getContent() resp.Revision::getContent() to get a page's content as a Content object.These two methods should be the ONLY way in which page content is accessed.Another important function of ContentHandler objects is to define custom action handlers for a content model, see ContentHandler::getActionOverrides().This is similar to what WikiPage::getActionOverrides() was already doing.==Serialization==With the ContentHandler facility, page content no longer has to be text based.Objects implementing the Content interface are used to represent and handle the content internally.For storage and data exchange, each content model supports at least one serialization format via ContentHandler::serializeContent($content).The list of supported formats for a given content model can be accessed using ContentHandler::getSupportedFormats().Content serialization formats are identified using MIME type like strings.The following formats are built in:*text/x-wiki-wikitext *text/javascript-for js pages *text/css-for css pages *text/plain-for future use, e.g.with plain text messages.*text/html-for future use, e.g.with plain html messages.*application/vnd.php.serialized-for future use with the api and for extensions *application/json-for future use with the api, and for use by extensions *application/xml-for future use with the api, and for use by extensions In PHP, use the corresponding CONTENT_FORMAT_XXX constant.Note that when using the API to access page content, especially action=edit, action=parse and action=query &prop=revisions, the model and format of the content should always be handled explicitly.Without that information, interpretation of the provided content is not reliable.The same applies to XML dumps generated via maintenance/dumpBackup.php or Special:Export.Also note that the API will provide encapsulated, serialized content-so if the API was called with format=json, and contentformat is also json(or rather, application/json), the page content is represented as a string containing an escaped json structure.Extensions that use JSON to serialize some types of page content may provide specialized API modules that allow access to that content in a more natural form.==Compatibility==The ContentHandler facility is introduced in a way that should allow all existing code to keep functioning at least for pages that contain wikitext or other text based content.However, a number of functions and hooks have been deprecated in favor of new versions that are aware of the page's content model, and will now generate warnings when used.Most importantly, the following functions have been deprecated:*Revisions::getText() is deprecated in favor Revisions::getContent()*WikiPage::getText() is deprecated in favor WikiPage::getContent() Also, the old Article::getContent()(which returns text) is superceded by Article::getContentObject().However, both methods should be avoided since they do not provide clean access to the page's actual content.For instance, they may return a system message for non-existing pages.Use WikiPage::getContent() instead.Code that relies on a textual representation of the page content should eventually be rewritten.However, ContentHandler::getContentText() provides a stop-gap that can be used to get text for a page.Its behavior is controlled by $wgContentHandlerTextFallback it
skin txt MediaWiki includes four core it has been set as the default in MediaWiki since the replacing Monobook it had been the default skin since then
Definition: skin.txt:10
const QUICK_RAND
doBatchPush(array $jobs, $flags)
static makeTitle($ns, $title, $fragment= '', $interwiki= '')
Create a new Title from a namespace index and a DB key.
Definition: Title.php:511
LoggerInterface $logger
Allows to change the fields on the form that will be generated $name
Definition: hooks.txt:300