includes/jobqueue/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 HashRing */
  51         protected $partitionRing;
  52         /** @var HashRing */
  53         protected $partitionPushRing;
  54         /** @var array (partition name => JobQueue) reverse sorted by weight */
  55         protected $partitionQueues = array();
  56
  57         /** @var BagOStuff */
  58         protected $cache;
  59
  60         /** @var int Maximum number of partitions to try */
  61         protected $maxPartitionsTry;
  62
  63         const CACHE_TTL_SHORT = 30; // integer; seconds to cache info without re-validating
  64         const CACHE_TTL_LONG = 300; // integer; seconds to cache info that is kept up to date
  65
  66         /**
  67          * @param array $params Possible keys:
  68          *  - sectionsByWiki      : A map of wiki IDs to section names.
  69          *                          Wikis will default to using the section "default".
  70          *  - partitionsBySection : Map of section names to maps of (partition name => weight).
  71          *                          A section called 'default' must be defined if not all wikis
  72          *                          have explicitly defined sections.
  73          *  - configByPartition   : Map of queue partition names to configuration arrays.
  74          *                          These configuration arrays are passed to JobQueue::factory().
  75          *                          The options set here are overridden by those passed to this
  76          *                          the federated queue itself (e.g. 'order' and 'claimTTL').
  77          *  - partitionsNoPush    : List of partition names that can handle pop() but not push().
  78          *                          This can be used to migrate away from a certain partition.
  79          *  - maxPartitionsTry    : Maximum number of times to attempt job insertion using
  80          *                          different partition queues. This improves availability
  81          *                          during failure, at the cost of added latency and somewhat
  82          *                          less reliable job de-duplication mechanisms.
  83          * @throws MWException
  84          */
  85         protected function __construct( array $params ) {
  86                 parent::__construct( $params );
  87                 $section = isset( $params['sectionsByWiki'][$this->wiki] )
  88                         ? $params['sectionsByWiki'][$this->wiki]
  89                         : 'default';
  90                 if ( !isset( $params['partitionsBySection'][$section] ) ) {
  91                         throw new MWException( "No configuration for section '$section'." );
  92                 }
  93                 $this->maxPartitionsTry = isset( $params['maxPartitionsTry'] )
  94                         ? $params['maxPartitionsTry']
  95                         : 2;
  96                 // Get the full partition map
  97                 $partitionMap = $params['partitionsBySection'][$section];
  98                 arsort( $partitionMap, SORT_NUMERIC );
  99                 // Get the partitions jobs can actually be pushed to
 100                 $partitionPushMap = $partitionMap;
 101                 if ( isset( $params['partitionsNoPush'] ) ) {
 102                         foreach ( $params['partitionsNoPush'] as $partition ) {
 103                                 unset( $partitionPushMap[$partition] );
 104                         }
 105                 }
 106                 // Get the config to pass to merge into each partition queue config
 107                 $baseConfig = $params;
 108                 foreach ( array( 'class', 'sectionsByWiki', 'maxPartitionsTry',
 109                         'partitionsBySection', 'configByPartition', 'partitionsNoPush' ) as $o
 110                 ) {
 111                         unset( $baseConfig[$o] ); // partition queue doesn't care about this
 112                 }
 113                 // Get the partition queue objects
 114                 foreach ( $partitionMap as $partition => $w ) {
 115                         if ( !isset( $params['configByPartition'][$partition] ) ) {
 116                                 throw new MWException( "No configuration for partition '$partition'." );
 117                         }
 118                         $this->partitionQueues[$partition] = JobQueue::factory(
 119                                 $baseConfig + $params['configByPartition'][$partition] );
 120                 }
 121                 // Ring of all partitions
 122                 $this->partitionRing = new HashRing( $partitionMap );
 123                 // Get the ring of partitions to push jobs into
 124                 if ( count( $partitionPushMap ) === count( $partitionMap ) ) {
 125                         $this->partitionPushRing = clone $this->partitionRing; // faster
 126                 } else {
 127                         $this->partitionPushRing = new HashRing( $partitionPushMap );
 128                 }
 129                 // Aggregate cache some per-queue values if there are multiple partition queues
 130                 $this->cache = count( $partitionMap ) > 1 ? wfGetMainCache() : new EmptyBagOStuff();
 131         }
 132
 133         protected function supportedOrders() {
 134                 // No FIFO due to partitioning, though "rough timestamp order" is supported
 135                 return array( 'undefined', 'random', 'timestamp' );
 136         }
 137
 138         protected function optimalOrder() {
 139                 return 'undefined'; // defer to the partitions
 140         }
 141
 142         protected function supportsDelayedJobs() {
 143                 return true; // defer checks to the partitions
 144         }
 145
 146         protected function doIsEmpty() {
 147                 $key = $this->getCacheKey( 'empty' );
 148
 149                 $isEmpty = $this->cache->get( $key );
 150                 if ( $isEmpty === 'true' ) {
 151                         return true;
 152                 } elseif ( $isEmpty === 'false' ) {
 153                         return false;
 154                 }
 155
 156                 $empty = true;
 157                 $failed = 0;
 158                 foreach ( $this->partitionQueues as $queue ) {
 159                         try {
 160                                 $empty = $empty && $queue->doIsEmpty();
 161                         } catch ( JobQueueError $e ) {
 162                                 ++$failed;
 163                                 $this->logException( $e );
 164                         }
 165                 }
 166                 $this->throwErrorIfAllPartitionsDown( $failed );
 167
 168                 $this->cache->add( $key, $empty ? 'true' : 'false', self::CACHE_TTL_LONG );
 169                 return $empty;
 170         }
 171
 172         protected function doGetSize() {
 173                 return $this->getCrossPartitionSum( 'size', 'doGetSize' );
 174         }
 175
 176         protected function doGetAcquiredCount() {
 177                 return $this->getCrossPartitionSum( 'acquiredcount', 'doGetAcquiredCount' );
 178         }
 179
 180         protected function doGetDelayedCount() {
 181                 return $this->getCrossPartitionSum( 'delayedcount', 'doGetDelayedCount' );
 182         }
 183
 184         protected function doGetAbandonedCount() {
 185                 return $this->getCrossPartitionSum( 'abandonedcount', 'doGetAbandonedCount' );
 186         }
 187
 188         /**
 189          * @param string $type
 190          * @param string $method
 191          * @return int
 192          */
 193         protected function getCrossPartitionSum( $type, $method ) {
 194                 $key = $this->getCacheKey( $type );
 195
 196                 $count = $this->cache->get( $key );
 197                 if ( $count !== false ) {
 198                         return $count;
 199                 }
 200
 201                 $failed = 0;
 202                 foreach ( $this->partitionQueues as $queue ) {
 203                         try {
 204                                 $count += $queue->$method();
 205                         } catch ( JobQueueError $e ) {
 206                                 ++$failed;
 207                                 $this->logException( $e );
 208                         }
 209                 }
 210                 $this->throwErrorIfAllPartitionsDown( $failed );
 211
 212                 $this->cache->set( $key, $count, self::CACHE_TTL_SHORT );
 213
 214                 return $count;
 215         }
 216
 217         protected function doBatchPush( array $jobs, $flags ) {
 218                 // Local ring variable that may be changed to point to a new ring on failure
 219                 $partitionRing = $this->partitionPushRing;
 220                 // Try to insert the jobs and update $partitionsTry on any failures.
 221                 // Retry to insert any remaning jobs again, ignoring the bad partitions.
 222                 $jobsLeft = $jobs;
 223                 // @codingStandardsIgnoreStart Generic.CodeAnalysis.ForLoopWithTestFunctionCall.NotAllowed
 224                 for ( $i = $this->maxPartitionsTry; $i > 0 && count( $jobsLeft ); --$i ) {
 225                         // @codingStandardsIgnoreEnd
 226                         try {
 227                                 $partitionRing->getLiveRing();
 228                         } catch ( UnexpectedValueException $e ) {
 229                                 break; // all servers down; nothing to insert to
 230                         }
 231                         $jobsLeft = $this->tryJobInsertions( $jobsLeft, $partitionRing, $flags );
 232                 }
 233                 if ( count( $jobsLeft ) ) {
 234                         throw new JobQueueError(
 235                                 "Could not insert job(s), {$this->maxPartitionsTry} partitions tried." );
 236                 }
 237         }
 238
 239         /**
 240          * @param array $jobs
 241          * @param HashRing $partitionRing
 242          * @param int $flags
 243          * @throws JobQueueError
 244          * @return array List of Job object that could not be inserted
 245          */
 246         protected function tryJobInsertions( array $jobs, HashRing &$partitionRing, $flags ) {
 247                 $jobsLeft = array();
 248
 249                 // Because jobs are spread across partitions, per-job de-duplication needs
 250                 // to use a consistent hash to avoid allowing duplicate jobs per partition.
 251                 // When inserting a batch of de-duplicated jobs, QOS_ATOMIC is disregarded.
 252                 $uJobsByPartition = array(); // (partition name => job list)
 253                 /** @var Job $job */
 254                 foreach ( $jobs as $key => $job ) {
 255                         if ( $job->ignoreDuplicates() ) {
 256                                 $sha1 = sha1( serialize( $job->getDeduplicationInfo() ) );
 257                                 $uJobsByPartition[$partitionRing->getLiveLocation( $sha1 )][] = $job;
 258                                 unset( $jobs[$key] );
 259                         }
 260                 }
 261                 // Get the batches of jobs that are not de-duplicated
 262                 if ( $flags & self::QOS_ATOMIC ) {
 263                         $nuJobBatches = array( $jobs ); // all or nothing
 264                 } else {
 265                         // Split the jobs into batches and spread them out over servers if there
 266                         // are many jobs. This helps keep the partitions even. Otherwise, send all
 267                         // the jobs to a single partition queue to avoids the extra connections.
 268                         $nuJobBatches = array_chunk( $jobs, 300 );
 269                 }
 270
 271                 // Insert the de-duplicated jobs into the queues...
 272                 foreach ( $uJobsByPartition as $partition => $jobBatch ) {
 273                         /** @var JobQueue $queue */
 274                         $queue = $this->partitionQueues[$partition];
 275                         try {
 276                                 $ok = true;
 277                                 $queue->doBatchPush( $jobBatch, $flags | self::QOS_ATOMIC );
 278                         } catch ( JobQueueError $e ) {
 279                                 $ok = false;
 280                                 $this->logException( $e );
 281                         }
 282                         if ( $ok ) {
 283                                 $key = $this->getCacheKey( 'empty' );
 284                                 $this->cache->set( $key, 'false', self::CACHE_TTL_LONG );
 285                         } else {
 286                                 if ( !$partitionRing->ejectFromLiveRing( $partition, 5 ) ) { // blacklist
 287                                         throw new JobQueueError( "Could not insert job(s), no partitions available." );
 288                                 }
 289                                 $jobsLeft = array_merge( $jobsLeft, $jobBatch ); // not inserted
 290                         }
 291                 }
 292
 293                 // Insert the jobs that are not de-duplicated into the queues...
 294                 foreach ( $nuJobBatches as $jobBatch ) {
 295                         $partition = ArrayUtils::pickRandom( $partitionRing->getLiveLocationWeights() );
 296                         $queue = $this->partitionQueues[$partition];
 297                         try {
 298                                 $ok = true;
 299                                 $queue->doBatchPush( $jobBatch, $flags | self::QOS_ATOMIC );
 300                         } catch ( JobQueueError $e ) {
 301                                 $ok = false;
 302                                 $this->logException( $e );
 303                         }
 304                         if ( $ok ) {
 305                                 $key = $this->getCacheKey( 'empty' );
 306                                 $this->cache->set( $key, 'false', self::CACHE_TTL_LONG );
 307                         } else {
 308                                 if ( !$partitionRing->ejectFromLiveRing( $partition, 5 ) ) { // blacklist
 309                                         throw new JobQueueError( "Could not insert job(s), no partitions available." );
 310                                 }
 311                                 $jobsLeft = array_merge( $jobsLeft, $jobBatch ); // not inserted
 312                         }
 313                 }
 314
 315                 return $jobsLeft;
 316         }
 317
 318         protected function doPop() {
 319                 $partitionsTry = $this->partitionRing->getLiveLocationWeights(); // (partition => weight)
 320
 321                 $failed = 0;
 322                 while ( count( $partitionsTry ) ) {
 323                         $partition = ArrayUtils::pickRandom( $partitionsTry );
 324                         if ( $partition === false ) {
 325                                 break; // all partitions at 0 weight
 326                         }
 327
 328                         /** @var JobQueue $queue */
 329                         $queue = $this->partitionQueues[$partition];
 330                         try {
 331                                 $job = $queue->pop();
 332                         } catch ( JobQueueError $e ) {
 333                                 ++$failed;
 334                                 $this->logException( $e );
 335                                 $job = false;
 336                         }
 337                         if ( $job ) {
 338                                 $job->metadata['QueuePartition'] = $partition;
 339
 340                                 return $job;
 341                         } else {
 342                                 unset( $partitionsTry[$partition] ); // blacklist partition
 343                         }
 344                 }
 345                 $this->throwErrorIfAllPartitionsDown( $failed );
 346
 347                 $key = $this->getCacheKey( 'empty' );
 348                 $this->cache->set( $key, 'true', self::CACHE_TTL_LONG );
 349
 350                 return false;
 351         }
 352
 353         protected function doAck( Job $job ) {
 354                 if ( !isset( $job->metadata['QueuePartition'] ) ) {
 355                         throw new MWException( "The given job has no defined partition name." );
 356                 }
 357
 358                 return $this->partitionQueues[$job->metadata['QueuePartition']]->ack( $job );
 359         }
 360
 361         protected function doIsRootJobOldDuplicate( Job $job ) {
 362                 $params = $job->getRootJobParams();
 363                 $sigature = $params['rootJobSignature'];
 364                 $partition = $this->partitionPushRing->getLiveLocation( $sigature );
 365                 try {
 366                         return $this->partitionQueues[$partition]->doIsRootJobOldDuplicate( $job );
 367                 } catch ( JobQueueError $e ) {
 368                         if ( $this->partitionPushRing->ejectFromLiveRing( $partition, 5 ) ) {
 369                                 $partition = $this->partitionPushRing->getLiveLocation( $sigature );
 370                                 return $this->partitionQueues[$partition]->doIsRootJobOldDuplicate( $job );
 371                         }
 372                 }
 373
 374                 return false;
 375         }
 376
 377         protected function doDeduplicateRootJob( Job $job ) {
 378                 $params = $job->getRootJobParams();
 379                 $sigature = $params['rootJobSignature'];
 380                 $partition = $this->partitionPushRing->getLiveLocation( $sigature );
 381                 try {
 382                         return $this->partitionQueues[$partition]->doDeduplicateRootJob( $job );
 383                 } catch ( JobQueueError $e ) {
 384                         if ( $this->partitionPushRing->ejectFromLiveRing( $partition, 5 ) ) {
 385                                 $partition = $this->partitionPushRing->getLiveLocation( $sigature );
 386                                 return $this->partitionQueues[$partition]->doDeduplicateRootJob( $job );
 387                         }
 388                 }
 389
 390                 return false;
 391         }
 392
 393         protected function doDelete() {
 394                 $failed = 0;
 395                 /** @var JobQueue $queue */
 396                 foreach ( $this->partitionQueues as $queue ) {
 397                         try {
 398                                 $queue->doDelete();
 399                         } catch ( JobQueueError $e ) {
 400                                 ++$failed;
 401                                 $this->logException( $e );
 402                         }
 403                 }
 404                 $this->throwErrorIfAllPartitionsDown( $failed );
 405                 return true;
 406         }
 407
 408         protected function doWaitForBackups() {
 409                 $failed = 0;
 410                 /** @var JobQueue $queue */
 411                 foreach ( $this->partitionQueues as $queue ) {
 412                         try {
 413                                 $queue->waitForBackups();
 414                         } catch ( JobQueueError $e ) {
 415                                 ++$failed;
 416                                 $this->logException( $e );
 417                         }
 418                 }
 419                 $this->throwErrorIfAllPartitionsDown( $failed );
 420         }
 421
 422         protected function doGetPeriodicTasks() {
 423                 $tasks = array();
 424                 /** @var JobQueue $queue */
 425                 foreach ( $this->partitionQueues as $partition => $queue ) {
 426                         foreach ( $queue->getPeriodicTasks() as $task => $def ) {
 427                                 $tasks["{$partition}:{$task}"] = $def;
 428                         }
 429                 }
 430
 431                 return $tasks;
 432         }
 433
 434         protected function doFlushCaches() {
 435                 static $types = array(
 436                         'empty',
 437                         'size',
 438                         'acquiredcount',
 439                         'delayedcount',
 440                         'abandonedcount'
 441                 );
 442
 443                 foreach ( $types as $type ) {
 444                         $this->cache->delete( $this->getCacheKey( $type ) );
 445                 }
 446
 447                 /** @var JobQueue $queue */
 448                 foreach ( $this->partitionQueues as $queue ) {
 449                         $queue->doFlushCaches();
 450                 }
 451         }
 452
 453         public function getAllQueuedJobs() {
 454                 $iterator = new AppendIterator();
 455
 456                 /** @var JobQueue $queue */
 457                 foreach ( $this->partitionQueues as $queue ) {
 458                         $iterator->append( $queue->getAllQueuedJobs() );
 459                 }
 460
 461                 return $iterator;
 462         }
 463
 464         public function getAllDelayedJobs() {
 465                 $iterator = new AppendIterator();
 466
 467                 /** @var JobQueue $queue */
 468                 foreach ( $this->partitionQueues as $queue ) {
 469                         $iterator->append( $queue->getAllDelayedJobs() );
 470                 }
 471
 472                 return $iterator;
 473         }
 474
 475         public function getCoalesceLocationInternal() {
 476                 return "JobQueueFederated:wiki:{$this->wiki}" .
 477                         sha1( serialize( array_keys( $this->partitionQueues ) ) );
 478         }
 479
 480         protected function doGetSiblingQueuesWithJobs( array $types ) {
 481                 $result = array();
 482
 483                 $failed = 0;
 484                 /** @var JobQueue $queue */
 485                 foreach ( $this->partitionQueues as $queue ) {
 486                         try {
 487                                 $nonEmpty = $queue->doGetSiblingQueuesWithJobs( $types );
 488                                 if ( is_array( $nonEmpty ) ) {
 489                                         $result = array_unique( array_merge( $result, $nonEmpty ) );
 490                                 } else {
 491                                         return null; // not supported on all partitions; bail
 492                                 }
 493                                 if ( count( $result ) == count( $types ) ) {
 494                                         break; // short-circuit
 495                                 }
 496                         } catch ( JobQueueError $e ) {
 497                                 ++$failed;
 498                                 $this->logException( $e );
 499                         }
 500                 }
 501                 $this->throwErrorIfAllPartitionsDown( $failed );
 502
 503                 return array_values( $result );
 504         }
 505
 506         protected function doGetSiblingQueueSizes( array $types ) {
 507                 $result = array();
 508                 $failed = 0;
 509                 /** @var JobQueue $queue */
 510                 foreach ( $this->partitionQueues as $queue ) {
 511                         try {
 512                                 $sizes = $queue->doGetSiblingQueueSizes( $types );
 513                                 if ( is_array( $sizes ) ) {
 514                                         foreach ( $sizes as $type => $size ) {
 515                                                 $result[$type] = isset( $result[$type] ) ? $result[$type] + $size : $size;
 516                                         }
 517                                 } else {
 518                                         return null; // not supported on all partitions; bail
 519                                 }
 520                         } catch ( JobQueueError $e ) {
 521                                 ++$failed;
 522                                 $this->logException( $e );
 523                         }
 524                 }
 525                 $this->throwErrorIfAllPartitionsDown( $failed );
 526
 527                 return $result;
 528         }
 529
 530         protected function logException( Exception $e ) {
 531                 wfDebugLog( 'JobQueueFederated', $e->getMessage() . "\n" . $e->getTraceAsString() );
 532         }
 533
 534         /**
 535          * Throw an error if no partitions available
 536          *
 537          * @param int $down The number of up partitions down
 538          * @return void
 539          * @throws JobQueueError
 540          */
 541         protected function throwErrorIfAllPartitionsDown( $down ) {
 542                 if ( $down >= count( $this->partitionQueues ) ) {
 543                         throw new JobQueueError( 'No queue partitions available.' );
 544                 }
 545         }
 546
 547         public function setTestingPrefix( $key ) {
 548                 /** @var JobQueue $queue */
 549                 foreach ( $this->partitionQueues as $queue ) {
 550                         $queue->setTestingPrefix( $key );
 551                 }
 552         }
 553
 554         /**
 555          * @param string $property
 556          * @return string
 557          */
 558         private function getCacheKey( $property ) {
 559                 list( $db, $prefix ) = wfSplitWikiID( $this->wiki );
 560
 561                 return wfForeignMemcKey( $db, $prefix, 'jobqueue', $this->type, $property );
 562         }
 563 }