includes/job/JobQueueFederated.php

   1 <?php
   2 /**
   3  * Job queue code for federated queues.
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18  * http://www.gnu.org/copyleft/gpl.html
  19  *
  20  * @file
  21  * @author Aaron Schulz
  22  */
  23
  24 /**
  25  * Class to handle enqueueing and running of background jobs for federated queues
  26  *
  27  * This class allows for queues to be partitioned into smaller queues.
  28  * A partition is defined by the configuration for a JobQueue instance.
  29  * For example, one can set $wgJobTypeConf['refreshLinks'] to point to a
  30  * JobQueueFederated instance, which itself would consist of three JobQueueRedis
  31  * instances, each using their own redis server. This would allow for the jobs
  32  * to be split (evenly or based on weights) accross multiple servers if a single
  33  * server becomes impractical or expensive. Different JobQueue classes can be mixed.
  34  *
  35  * The basic queue configuration (e.g. "order", "claimTTL") of a federated queue
  36  * is inherited by the partition queues. Additional configuration defines what
  37  * section each wiki is in, what partition queues each section uses (and their weight),
  38  * and the JobQueue configuration for each partition. Some sections might only need a
  39  * single queue partition, like the sections for groups of small wikis.
  40  *
  41  * If used for performance, then $wgMainCacheType should be set to memcached/redis.
  42  * Note that "fifo" cannot be used for the ordering, since the data is distributed.
  43  * One can still use "timestamp" instead, as in "roughly timestamp ordered". Also,
  44  * queue classes used by this should ignore down servers (with TTL) to avoid slowness.
  45  *
  46  * @ingroup JobQueue
  47  * @since 1.22
  48  */
  49 class JobQueueFederated extends JobQueue {
  50         /** @var array (partition name => weight) reverse sorted by weight */
  51         protected $partitionMap = array();
  52
  53         /** @var array (partition name => JobQueue) reverse sorted by weight */
  54         protected $partitionQueues = array();
  55
  56         /** @var HashRing */
  57         protected $partitionPushRing;
  58
  59         /** @var BagOStuff */
  60         protected $cache;
  61
  62         /** @var int Maximum number of partitions to try */
  63         protected $maxPartitionsTry;
  64
  65         const CACHE_TTL_SHORT = 30; // integer; seconds to cache info without re-validating
  66         const CACHE_TTL_LONG = 300; // integer; seconds to cache info that is kept up to date
  67
  68         /**
  69          * @params include:
  70          *  - sectionsByWiki      : A map of wiki IDs to section names.
  71          *                          Wikis will default to using the section "default".
  72          *  - partitionsBySection : Map of section names to maps of (partition name => weight).
  73          *                          A section called 'default' must be defined if not all wikis
  74          *                          have explicitly defined sections.
  75          *  - configByPartition   : Map of queue partition names to configuration arrays.
  76          *                          These configuration arrays are passed to JobQueue::factory().
  77          *                          The options set here are overriden by those passed to this
  78          *                          the federated queue itself (e.g. 'order' and 'claimTTL').
  79          *  - partitionsNoPush    : List of partition names that can handle pop() but not push().
  80          *                          This can be used to migrate away from a certain partition.
  81          *  - maxPartitionsTry    : Maximum number of times to attempt job insertion using
  82          *                          different partition queues. This improves availability
  83          *                          during failure, at the cost of added latency and somewhat
  84          *                          less reliable job de-duplication mechanisms.
  85          * @param array $params
  86          * @throws MWException
  87          */
  88         protected function __construct( array $params ) {
  89                 parent::__construct( $params );
  90                 $section = isset( $params['sectionsByWiki'][$this->wiki] )
  91                         ? $params['sectionsByWiki'][$this->wiki]
  92                         : 'default';
  93                 if ( !isset( $params['partitionsBySection'][$section] ) ) {
  94                         throw new MWException( "No configuration for section '$section'." );
  95                 }
  96                 $this->maxPartitionsTry = isset( $params['maxPartitionsTry'] )
  97                         ? $params['maxPartitionsTry']
  98                         : 2;
  99                 // Get the full partition map
 100                 $this->partitionMap = $params['partitionsBySection'][$section];
 101                 arsort( $this->partitionMap, SORT_NUMERIC );
 102                 // Get the partitions jobs can actually be pushed to
 103                 $partitionPushMap = $this->partitionMap;
 104                 if ( isset( $params['partitionsNoPush'] ) ) {
 105                         foreach ( $params['partitionsNoPush'] as $partition ) {
 106                                 unset( $partitionPushMap[$partition] );
 107                         }
 108                 }
 109                 // Get the config to pass to merge into each partition queue config
 110                 $baseConfig = $params;
 111                 foreach ( array( 'class', 'sectionsByWiki', 'maxPartitionsTry',
 112                         'partitionsBySection', 'configByPartition', 'partitionsNoPush' ) as $o
 113                 ) {
 114                         unset( $baseConfig[$o] ); // partition queue doesn't care about this
 115                 }
 116                 // Get the partition queue objects
 117                 foreach ( $this->partitionMap as $partition => $w ) {
 118                         if ( !isset( $params['configByPartition'][$partition] ) ) {
 119                                 throw new MWException( "No configuration for partition '$partition'." );
 120                         }
 121                         $this->partitionQueues[$partition] = JobQueue::factory(
 122                                 $baseConfig + $params['configByPartition'][$partition] );
 123                 }
 124                 // Get the ring of partitions to push jobs into
 125                 $this->partitionPushRing = new HashRing( $partitionPushMap );
 126                 // Aggregate cache some per-queue values if there are multiple partition queues
 127                 $this->cache = count( $this->partitionMap ) > 1 ? wfGetMainCache() : new EmptyBagOStuff();
 128         }
 129
 130         protected function supportedOrders() {
 131                 // No FIFO due to partitioning, though "rough timestamp order" is supported
 132                 return array( 'undefined', 'random', 'timestamp' );
 133         }
 134
 135         protected function optimalOrder() {
 136                 return 'undefined'; // defer to the partitions
 137         }
 138
 139         protected function supportsDelayedJobs() {
 140                 return true; // defer checks to the partitions
 141         }
 142
 143         protected function doIsEmpty() {
 144                 $key = $this->getCacheKey( 'empty' );
 145
 146                 $isEmpty = $this->cache->get( $key );
 147                 if ( $isEmpty === 'true' ) {
 148                         return true;
 149                 } elseif ( $isEmpty === 'false' ) {
 150                         return false;
 151                 }
 152
 153                 $empty = true;
 154                 $failed = 0;
 155                 foreach ( $this->partitionQueues as $queue ) {
 156                         try {
 157                                 $empty = $empty && $queue->doIsEmpty();
 158                         } catch ( JobQueueError $e ) {
 159                                 ++$failed;
 160                                 MWExceptionHandler::logException( $e );
 161                         }
 162                 }
 163                 $this->throwErrorIfAllPartitionsDown( $failed );
 164
 165                 $this->cache->add( $key, $empty ? 'true' : 'false', self::CACHE_TTL_LONG );
 166                 return $empty;
 167         }
 168
 169         protected function doGetSize() {
 170                 return $this->getCrossPartitionSum( 'size', 'doGetSize' );
 171         }
 172
 173         protected function doGetAcquiredCount() {
 174                 return $this->getCrossPartitionSum( 'acquiredcount', 'doGetAcquiredCount' );
 175         }
 176
 177         protected function doGetDelayedCount() {
 178                 return $this->getCrossPartitionSum( 'delayedcount', 'doGetDelayedCount' );
 179         }
 180
 181         protected function doGetAbandonedCount() {
 182                 return $this->getCrossPartitionSum( 'abandonedcount', 'doGetAbandonedCount' );
 183         }
 184
 185         /**
 186          * @param string $type
 187          * @param string $method
 188          * @return int
 189          */
 190         protected function getCrossPartitionSum( $type, $method ) {
 191                 $key = $this->getCacheKey( $type );
 192
 193                 $count = $this->cache->get( $key );
 194                 if ( is_int( $count ) ) {
 195                         return $count;
 196                 }
 197
 198                 $failed = 0;
 199                 foreach ( $this->partitionQueues as $queue ) {
 200                         try {
 201                                 $count += $queue->$method();
 202                         } catch ( JobQueueError $e ) {
 203                                 ++$failed;
 204                                 MWExceptionHandler::logException( $e );
 205                         }
 206                 }
 207                 $this->throwErrorIfAllPartitionsDown( $failed );
 208
 209                 $this->cache->set( $key, $count, self::CACHE_TTL_SHORT );
 210
 211                 return $count;
 212         }
 213
 214         protected function doBatchPush( array $jobs, $flags ) {
 215                 // Local ring variable that may be changed to point to a new ring on failure
 216                 $partitionRing = $this->partitionPushRing;
 217                 // Try to insert the jobs and update $partitionsTry on any failures.
 218                 // Retry to insert any remaning jobs again, ignoring the bad partitions.
 219                 $jobsLeft = $jobs;
 220                 for ( $i = $this->maxPartitionsTry; $i > 0 && count( $jobsLeft ); --$i ) {
 221                         $jobsLeft = $this->tryJobInsertions( $jobsLeft, $partitionRing, $flags );
 222                 }
 223                 if ( count( $jobsLeft ) ) {
 224                         throw new JobQueueError(
 225                                 "Could not insert job(s), {$this->maxPartitionsTry} partitions tried." );
 226                 }
 227
 228                 return true;
 229         }
 230
 231         /**
 232          * @param array $jobs
 233          * @param HashRing $partitionRing
 234          * @param int $flags
 235          * @throws JobQueueError
 236          * @return array List of Job object that could not be inserted
 237          */
 238         protected function tryJobInsertions( array $jobs, HashRing &$partitionRing, $flags ) {
 239                 $jobsLeft = array();
 240
 241                 // Because jobs are spread across partitions, per-job de-duplication needs
 242                 // to use a consistent hash to avoid allowing duplicate jobs per partition.
 243                 // When inserting a batch of de-duplicated jobs, QOS_ATOMIC is disregarded.
 244                 $uJobsByPartition = array(); // (partition name => job list)
 245                 /** @var Job $job */
 246                 foreach ( $jobs as $key => $job ) {
 247                         if ( $job->ignoreDuplicates() ) {
 248                                 $sha1 = sha1( serialize( $job->getDeduplicationInfo() ) );
 249                                 $uJobsByPartition[$partitionRing->getLocation( $sha1 )][] = $job;
 250                                 unset( $jobs[$key] );
 251                         }
 252                 }
 253                 // Get the batches of jobs that are not de-duplicated
 254                 if ( $flags & self::QOS_ATOMIC ) {
 255                         $nuJobBatches = array( $jobs ); // all or nothing
 256                 } else {
 257                         // Split the jobs into batches and spread them out over servers if there
 258                         // are many jobs. This helps keep the partitions even. Otherwise, send all
 259                         // the jobs to a single partition queue to avoids the extra connections.
 260                         $nuJobBatches = array_chunk( $jobs, 300 );
 261                 }
 262
 263                 // Insert the de-duplicated jobs into the queues...
 264                 foreach ( $uJobsByPartition as $partition => $jobBatch ) {
 265                         /** @var JobQueue $queue */
 266                         $queue = $this->partitionQueues[$partition];
 267                         try {
 268                                 $ok = $queue->doBatchPush( $jobBatch, $flags | self::QOS_ATOMIC );
 269                         } catch ( JobQueueError $e ) {
 270                                 $ok = false;
 271                                 MWExceptionHandler::logException( $e );
 272                         }
 273                         if ( $ok ) {
 274                                 $key = $this->getCacheKey( 'empty' );
 275                                 $this->cache->set( $key, 'false', JobQueueDB::CACHE_TTL_LONG );
 276                         } else {
 277                                 $partitionRing = $partitionRing->newWithoutLocation( $partition ); // blacklist
 278                                 if ( !$partitionRing ) {
 279                                         throw new JobQueueError( "Could not insert job(s), no partitions available." );
 280                                 }
 281                                 $jobsLeft = array_merge( $jobsLeft, $jobBatch ); // not inserted
 282                         }
 283                 }
 284
 285                 // Insert the jobs that are not de-duplicated into the queues...
 286                 foreach ( $nuJobBatches as $jobBatch ) {
 287                         $partition = ArrayUtils::pickRandom( $partitionRing->getLocationWeights() );
 288                         $queue = $this->partitionQueues[$partition];
 289                         try {
 290                                 $ok = $queue->doBatchPush( $jobBatch, $flags | self::QOS_ATOMIC );
 291                         } catch ( JobQueueError $e ) {
 292                                 $ok = false;
 293                                 MWExceptionHandler::logException( $e );
 294                         }
 295                         if ( $ok ) {
 296                                 $key = $this->getCacheKey( 'empty' );
 297                                 $this->cache->set( $key, 'false', JobQueueDB::CACHE_TTL_LONG );
 298                         } else {
 299                                 $partitionRing = $partitionRing->newWithoutLocation( $partition ); // blacklist
 300                                 if ( !$partitionRing ) {
 301                                         throw new JobQueueError( "Could not insert job(s), no partitions available." );
 302                                 }
 303                                 $jobsLeft = array_merge( $jobsLeft, $jobBatch ); // not inserted
 304                         }
 305                 }
 306
 307                 return $jobsLeft;
 308         }
 309
 310         protected function doPop() {
 311                 $key = $this->getCacheKey( 'empty' );
 312
 313                 $isEmpty = $this->cache->get( $key );
 314                 if ( $isEmpty === 'true' ) {
 315                         return false;
 316                 }
 317
 318                 $partitionsTry = $this->partitionMap; // (partition => weight)
 319
 320                 $failed = 0;
 321                 while ( count( $partitionsTry ) ) {
 322                         $partition = ArrayUtils::pickRandom( $partitionsTry );
 323                         if ( $partition === false ) {
 324                                 break; // all partitions at 0 weight
 325                         }
 326
 327                         /** @var JobQueue $queue */
 328                         $queue = $this->partitionQueues[$partition];
 329                         try {
 330                                 $job = $queue->pop();
 331                         } catch ( JobQueueError $e ) {
 332                                 ++$failed;
 333                                 MWExceptionHandler::logException( $e );
 334                                 $job = false;
 335                         }
 336                         if ( $job ) {
 337                                 $job->metadata['QueuePartition'] = $partition;
 338
 339                                 return $job;
 340                         } else {
 341                                 unset( $partitionsTry[$partition] ); // blacklist partition
 342                         }
 343                 }
 344                 $this->throwErrorIfAllPartitionsDown( $failed );
 345
 346                 $this->cache->set( $key, 'true', JobQueueDB::CACHE_TTL_LONG );
 347
 348                 return false;
 349         }
 350
 351         protected function doAck( Job $job ) {
 352                 if ( !isset( $job->metadata['QueuePartition'] ) ) {
 353                         throw new MWException( "The given job has no defined partition name." );
 354                 }
 355
 356                 return $this->partitionQueues[$job->metadata['QueuePartition']]->ack( $job );
 357         }
 358
 359         protected function doIsRootJobOldDuplicate( Job $job ) {
 360                 $params = $job->getRootJobParams();
 361                 $partitions = $this->partitionPushRing->getLocations( $params['rootJobSignature'], 2 );
 362                 try {
 363                         return $this->partitionQueues[$partitions[0]]->doIsRootJobOldDuplicate( $job );
 364                 } catch ( JobQueueError $e ) {
 365                         if ( isset( $partitions[1] ) ) { // check fallback partition
 366                                 return $this->partitionQueues[$partitions[1]]->doIsRootJobOldDuplicate( $job );
 367                         }
 368                 }
 369
 370                 return false;
 371         }
 372
 373         protected function doDeduplicateRootJob( Job $job ) {
 374                 $params = $job->getRootJobParams();
 375                 $partitions = $this->partitionPushRing->getLocations( $params['rootJobSignature'], 2 );
 376                 try {
 377                         return $this->partitionQueues[$partitions[0]]->doDeduplicateRootJob( $job );
 378                 } catch ( JobQueueError $e ) {
 379                         if ( isset( $partitions[1] ) ) { // check fallback partition
 380                                 return $this->partitionQueues[$partitions[1]]->doDeduplicateRootJob( $job );
 381                         }
 382                 }
 383
 384                 return false;
 385         }
 386
 387         protected function doDelete() {
 388                 $failed = 0;
 389                 /** @var JobQueue $queue */
 390                 foreach ( $this->partitionQueues as $queue ) {
 391                         try {
 392                                 $queue->doDelete();
 393                         } catch ( JobQueueError $e ) {
 394                                 ++$failed;
 395                                 MWExceptionHandler::logException( $e );
 396                         }
 397                 }
 398                 $this->throwErrorIfAllPartitionsDown( $failed );
 399                 return true;
 400         }
 401
 402         protected function doWaitForBackups() {
 403                 $failed = 0;
 404                 /** @var JobQueue $queue */
 405                 foreach ( $this->partitionQueues as $queue ) {
 406                         try {
 407                                 $queue->waitForBackups();
 408                         } catch ( JobQueueError $e ) {
 409                                 ++$failed;
 410                                 MWExceptionHandler::logException( $e );
 411                         }
 412                 }
 413                 $this->throwErrorIfAllPartitionsDown( $failed );
 414         }
 415
 416         protected function doGetPeriodicTasks() {
 417                 $tasks = array();
 418                 /** @var JobQueue $queue */
 419                 foreach ( $this->partitionQueues as $partition => $queue ) {
 420                         foreach ( $queue->getPeriodicTasks() as $task => $def ) {
 421                                 $tasks["{$partition}:{$task}"] = $def;
 422                         }
 423                 }
 424
 425                 return $tasks;
 426         }
 427
 428         protected function doFlushCaches() {
 429                 static $types = array(
 430                         'empty',
 431                         'size',
 432                         'acquiredcount',
 433                         'delayedcount',
 434                         'abandonedcount'
 435                 );
 436
 437                 foreach ( $types as $type ) {
 438                         $this->cache->delete( $this->getCacheKey( $type ) );
 439                 }
 440
 441                 /** @var JobQueue $queue */
 442                 foreach ( $this->partitionQueues as $queue ) {
 443                         $queue->doFlushCaches();
 444                 }
 445         }
 446
 447         public function getAllQueuedJobs() {
 448                 $iterator = new AppendIterator();
 449
 450                 /** @var JobQueue $queue */
 451                 foreach ( $this->partitionQueues as $queue ) {
 452                         $iterator->append( $queue->getAllQueuedJobs() );
 453                 }
 454
 455                 return $iterator;
 456         }
 457
 458         public function getAllDelayedJobs() {
 459                 $iterator = new AppendIterator();
 460
 461                 /** @var JobQueue $queue */
 462                 foreach ( $this->partitionQueues as $queue ) {
 463                         $iterator->append( $queue->getAllDelayedJobs() );
 464                 }
 465
 466                 return $iterator;
 467         }
 468
 469         public function getCoalesceLocationInternal() {
 470                 return "JobQueueFederated:wiki:{$this->wiki}" .
 471                         sha1( serialize( array_keys( $this->partitionMap ) ) );
 472         }
 473
 474         protected function doGetSiblingQueuesWithJobs( array $types ) {
 475                 $result = array();
 476
 477                 $failed = 0;
 478                 /** @var JobQueue $queue */
 479                 foreach ( $this->partitionQueues as $queue ) {
 480                         try {
 481                                 $nonEmpty = $queue->doGetSiblingQueuesWithJobs( $types );
 482                                 if ( is_array( $nonEmpty ) ) {
 483                                         $result = array_unique( array_merge( $result, $nonEmpty ) );
 484                                 } else {
 485                                         return null; // not supported on all partitions; bail
 486                                 }
 487                                 if ( count( $result ) == count( $types ) ) {
 488                                         break; // short-circuit
 489                                 }
 490                         } catch ( JobQueueError $e ) {
 491                                 ++$failed;
 492                                 MWExceptionHandler::logException( $e );
 493                         }
 494                 }
 495                 $this->throwErrorIfAllPartitionsDown( $failed );
 496
 497                 return array_values( $result );
 498         }
 499
 500         protected function doGetSiblingQueueSizes( array $types ) {
 501                 $result = array();
 502                 $failed = 0;
 503                 /** @var JobQueue $queue */
 504                 foreach ( $this->partitionQueues as $queue ) {
 505                         try {
 506                                 $sizes = $queue->doGetSiblingQueueSizes( $types );
 507                                 if ( is_array( $sizes ) ) {
 508                                         foreach ( $sizes as $type => $size ) {
 509                                                 $result[$type] = isset( $result[$type] ) ? $result[$type] + $size : $size;
 510                                         }
 511                                 } else {
 512                                         return null; // not supported on all partitions; bail
 513                                 }
 514                         } catch ( JobQueueError $e ) {
 515                                 ++$failed;
 516                                 MWExceptionHandler::logException( $e );
 517                         }
 518                 }
 519                 $this->throwErrorIfAllPartitionsDown( $failed );
 520
 521                 return $result;
 522         }
 523
 524         /**
 525          * Throw an error if no partitions available
 526          *
 527          * @param int $down The number of up partitions down
 528          * @return void
 529          * @throws JobQueueError
 530          */
 531         protected function throwErrorIfAllPartitionsDown( $down ) {
 532                 if ( $down >= count( $this->partitionQueues ) ) {
 533                         throw new JobQueueError( 'No queue partitions available.' );
 534                 }
 535         }
 536
 537         public function setTestingPrefix( $key ) {
 538                 /** @var JobQueue $queue */
 539                 foreach ( $this->partitionQueues as $queue ) {
 540                         $queue->setTestingPrefix( $key );
 541                 }
 542         }
 543
 544         /**
 545          * @param $property
 546          * @return string
 547          */
 548         private function getCacheKey( $property ) {
 549                 list( $db, $prefix ) = wfSplitWikiID( $this->wiki );
 550
 551                 return wfForeignMemcKey( $db, $prefix, 'jobqueue', $this->type, $property );
 552         }
 553 }