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".
  44  *
  45  * @ingroup JobQueue
  46  * @since 1.22
  47  */
  48 class JobQueueFederated extends JobQueue {
  49         /** @var Array (wiki ID => section name) */
  50         protected $sectionsByWiki = array();
  51         /** @var Array (section name => (partition name => weight)) */
  52         protected $partitionsBySection = array();
  53         /** @var Array (section name => config array) */
  54         protected $configByPartition = array();
  55         /** @var Array (partition names => integer) */
  56         protected $partitionsNoPush = array();
  57
  58         /** @var HashRing */
  59         protected $partitionRing;
  60         /** @var Array (partition name => JobQueue) */
  61         protected $partitionQueues = array();
  62         /** @var BagOStuff */
  63         protected $cache;
  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          * @param array $params
  82          */
  83         protected function __construct( array $params ) {
  84                 parent::__construct( $params );
  85                 $this->sectionsByWiki = isset( $params['sectionsByWiki'] )
  86                         ? $params['sectionsByWiki']
  87                         : array(); // all in "default" section
  88                 $this->partitionsBySection = $params['partitionsBySection'];
  89                 $this->configByPartition = $params['configByPartition'];
  90                 if ( isset( $params['partitionsNoPush'] ) ) {
  91                         $this->partitionsNoPush = array_flip( $params['partitionsNoPush'] );
  92                 }
  93                 $baseConfig = $params;
  94                 foreach ( array( 'class', 'sectionsByWiki',
  95                         'partitionsBySection', 'configByPartition', 'partitionsNoPush' ) as $o )
  96                 {
  97                         unset( $baseConfig[$o] );
  98                 }
  99                 foreach ( $this->getPartitionMap() as $partition => $w ) {
 100                         if ( !isset( $this->configByPartition[$partition] ) ) {
 101                                 throw new MWException( "No configuration for partition '$partition'." );
 102                         }
 103                         $this->partitionQueues[$partition] = JobQueue::factory(
 104                                 $baseConfig + $this->configByPartition[$partition]
 105                         );
 106                 }
 107                 // Get the ring of partitions to push job de-duplication information into
 108                 $partitionsTry = array_diff_key(
 109                         $this->getPartitionMap(),
 110                         $this->partitionsNoPush
 111                 ); // (partition => weight)
 112                 $this->partitionRing = new HashRing( $partitionsTry );
 113                 // Aggregate cache some per-queue values if there are multiple partition queues
 114                 $this->cache = $this->isFederated() ? wfGetMainCache() : new EmptyBagOStuff();
 115         }
 116
 117         protected function supportedOrders() {
 118                 // No FIFO due to partitioning, though "rough timestamp order" is supported
 119                 return array( 'undefined', 'random', 'timestamp' );
 120         }
 121
 122         protected function optimalOrder() {
 123                 return 'undefined'; // defer to the partitions
 124         }
 125
 126         protected function supportsDelayedJobs() {
 127                 return true; // defer checks to the partitions
 128         }
 129
 130         protected function doIsEmpty() {
 131                 $key = $this->getCacheKey( 'empty' );
 132
 133                 $isEmpty = $this->cache->get( $key );
 134                 if ( $isEmpty === 'true' ) {
 135                         return true;
 136                 } elseif ( $isEmpty === 'false' ) {
 137                         return false;
 138                 }
 139
 140                 foreach ( $this->partitionQueues as $queue ) {
 141                         if ( !$queue->doIsEmpty() ) {
 142                                 $this->cache->add( $key, 'false', self::CACHE_TTL_LONG );
 143                                 return false;
 144                         }
 145                 }
 146
 147                 $this->cache->add( $key, 'true', self::CACHE_TTL_LONG );
 148                 return true;
 149         }
 150
 151         protected function doGetSize() {
 152                 return $this->getCrossPartitionSum( 'size', 'doGetSize' );
 153         }
 154
 155         protected function doGetAcquiredCount() {
 156                 return $this->getCrossPartitionSum( 'acquiredcount', 'doGetAcquiredCount' );
 157         }
 158
 159         protected function doGetDelayedCount() {
 160                 return $this->getCrossPartitionSum( 'delayedcount', 'doGetDelayedCount' );
 161         }
 162
 163         protected function doGetAbandonedCount() {
 164                 return $this->getCrossPartitionSum( 'abandonedcount', 'doGetAbandonedCount' );
 165         }
 166
 167         /**
 168          * @param string $type
 169          * @param string $method
 170          * @return integer
 171          */
 172         protected function getCrossPartitionSum( $type, $method ) {
 173                 $key = $this->getCacheKey( $type );
 174
 175                 $count = $this->cache->get( $key );
 176                 if ( is_int( $count ) ) {
 177                         return $count;
 178                 }
 179
 180                 $count = 0;
 181                 foreach ( $this->partitionQueues as $queue ) {
 182                         $count += $queue->$method();
 183                 }
 184
 185                 $this->cache->set( $key, $count, self::CACHE_TTL_SHORT );
 186                 return $count;
 187         }
 188
 189         protected function doBatchPush( array $jobs, $flags ) {
 190                 if ( !count( $jobs ) ) {
 191                         return true; // nothing to do
 192                 }
 193
 194                 $partitionsTry = array_diff_key(
 195                         $this->getPartitionMap(),
 196                         $this->partitionsNoPush
 197                 ); // (partition => weight)
 198
 199                 // Try to insert the jobs and update $partitionsTry on any failures
 200                 $jobsLeft = $this->tryJobInsertions( $jobs, $partitionsTry, $flags );
 201                 if ( count( $jobsLeft ) ) { // some jobs failed to insert?
 202                         // Try to insert the remaning jobs once more, ignoring the bad partitions
 203                         return !count( $this->tryJobInsertions( $jobsLeft, $partitionsTry, $flags ) );
 204                 } else {
 205                         return true;
 206                 }
 207         }
 208
 209         /**
 210          * @param array $jobs
 211          * @param array $partitionsTry
 212          * @param integer $flags
 213          * @return array List of Job object that could not be inserted
 214          */
 215         protected function tryJobInsertions( array $jobs, array &$partitionsTry, $flags ) {
 216                 if ( !count( $partitionsTry ) ) {
 217                         return $jobs; // can't insert anything
 218                 }
 219
 220                 $jobsLeft = array();
 221
 222                 $partitionRing = new HashRing( $partitionsTry );
 223                 // Because jobs are spread across partitions, per-job de-duplication needs
 224                 // to use a consistent hash to avoid allowing duplicate jobs per partition.
 225                 // When inserting a batch of de-duplicated jobs, QOS_ATOMIC is disregarded.
 226                 $uJobsByPartition = array(); // (partition name => job list)
 227                 foreach ( $jobs as $key => $job ) {
 228                         if ( $job->ignoreDuplicates() ) {
 229                                 $sha1 = sha1( serialize( $job->getDeduplicationInfo() ) );
 230                                 $uJobsByPartition[$partitionRing->getLocation( $sha1 )][] = $job;
 231                                 unset( $jobs[$key] );
 232                         }
 233                 }
 234                 // Get the batches of jobs that are not de-duplicated
 235                 if ( $flags & self::QOS_ATOMIC ) {
 236                         $nuJobBatches = array( $jobs ); // all or nothing
 237                 } else {
 238                         // Split the jobs into batches and spread them out over servers if there
 239                         // are many jobs. This helps keep the partitions even. Otherwise, send all
 240                         // the jobs to a single partition queue to avoids the extra connections.
 241                         $nuJobBatches = array_chunk( $jobs, 300 );
 242                 }
 243
 244                 // Insert the de-duplicated jobs into the queues...
 245                 foreach ( $uJobsByPartition as $partition => $jobBatch ) {
 246                         $queue = $this->partitionQueues[$partition];
 247                         if ( $queue->doBatchPush( $jobBatch, $flags ) ) {
 248                                 $key = $this->getCacheKey( 'empty' );
 249                                 $this->cache->set( $key, 'false', JobQueueDB::CACHE_TTL_LONG );
 250                         } else {
 251                                 unset( $partitionsTry[$partition] ); // blacklist partition
 252                                 $jobsLeft = array_merge( $jobsLeft, $jobBatch ); // not inserted
 253                         }
 254                 }
 255                 // Insert the jobs that are not de-duplicated into the queues...
 256                 foreach ( $nuJobBatches as $jobBatch ) {
 257                         $partition = ArrayUtils::pickRandom( $partitionsTry );
 258                         if ( $partition === false ) { // all partitions at 0 weight?
 259                                 $jobsLeft = array_merge( $jobsLeft, $jobBatch ); // not inserted
 260                         } else {
 261                                 $queue = $this->partitionQueues[$partition];
 262                                 if ( $queue->doBatchPush( $jobBatch, $flags ) ) {
 263                                         $key = $this->getCacheKey( 'empty' );
 264                                         $this->cache->set( $key, 'false', JobQueueDB::CACHE_TTL_LONG );
 265                                 } else {
 266                                         unset( $partitionsTry[$partition] ); // blacklist partition
 267                                         $jobsLeft = array_merge( $jobsLeft, $jobBatch ); // not inserted
 268                                 }
 269                         }
 270                 }
 271
 272                 return $jobsLeft;
 273         }
 274
 275         protected function doPop() {
 276                 $key = $this->getCacheKey( 'empty' );
 277
 278                 $isEmpty = $this->cache->get( $key );
 279                 if ( $isEmpty === 'true' ) {
 280                         return false;
 281                 }
 282
 283                 $partitionsTry = $this->getPartitionMap(); // (partition => weight)
 284
 285                 while ( count( $partitionsTry ) ) {
 286                         $partition = ArrayUtils::pickRandom( $partitionsTry );
 287                         if ( $partition === false ) {
 288                                 break; // all partitions at 0 weight
 289                         }
 290                         $queue = $this->partitionQueues[$partition];
 291                         $job = $queue->pop();
 292                         if ( $job ) {
 293                                 $job->metadata['QueuePartition'] = $partition;
 294                                 return $job;
 295                         } else {
 296                                 unset( $partitionsTry[$partition] ); // blacklist partition
 297                         }
 298                 }
 299
 300                 $this->cache->set( $key, 'true', JobQueueDB::CACHE_TTL_LONG );
 301                 return false;
 302         }
 303
 304         protected function doAck( Job $job ) {
 305                 if ( !isset( $job->metadata['QueuePartition'] ) ) {
 306                         throw new MWException( "The given job has no defined partition name." );
 307                 }
 308                 return $this->partitionQueues[$job->metadata['QueuePartition']]->ack( $job );
 309         }
 310
 311         protected function doIsRootJobOldDuplicate( Job $job ) {
 312                 $params = $job->getRootJobParams();
 313                 $partitions = $this->partitionRing->getLocations( $params['rootJobSignature'], 2 );
 314                 try {
 315                         return $this->partitionQueues[$partitions[0]]->doIsRootJobOldDuplicate( $job );
 316                 } catch ( MWException $e ) {
 317                         if ( isset( $partitions[1] ) ) { // check fallback partition
 318                                 return $this->partitionQueues[$partitions[1]]->doIsRootJobOldDuplicate( $job );
 319                         }
 320                 }
 321                 return false;
 322         }
 323
 324         protected function doDeduplicateRootJob( Job $job ) {
 325                 $params = $job->getRootJobParams();
 326                 $partitions = $this->partitionRing->getLocations( $params['rootJobSignature'], 2 );
 327                 try {
 328                         return $this->partitionQueues[$partitions[0]]->doDeduplicateRootJob( $job );
 329                 } catch ( MWException $e ) {
 330                         if ( isset( $partitions[1] ) ) { // check fallback partition
 331                                 return $this->partitionQueues[$partitions[1]]->doDeduplicateRootJob( $job );
 332                         }
 333                 }
 334                 return false;
 335         }
 336
 337         protected function doDelete() {
 338                 foreach ( $this->partitionQueues as $queue ) {
 339                         $queue->doDelete();
 340                 }
 341         }
 342
 343         protected function doWaitForBackups() {
 344                 foreach ( $this->partitionQueues as $queue ) {
 345                         $queue->waitForBackups();
 346                 }
 347         }
 348
 349         protected function doGetPeriodicTasks() {
 350                 $tasks = array();
 351                 foreach ( $this->partitionQueues as $partition => $queue ) {
 352                         foreach ( $queue->getPeriodicTasks() as $task => $def ) {
 353                                 $tasks["{$partition}:{$task}"] = $def;
 354                         }
 355                 }
 356                 return $tasks;
 357         }
 358
 359         protected function doFlushCaches() {
 360                 static $types = array(
 361                         'empty',
 362                         'size',
 363                         'acquiredcount',
 364                         'delayedcount',
 365                         'abandonedcount'
 366                 );
 367                 foreach ( $types as $type ) {
 368                         $this->cache->delete( $this->getCacheKey( $type ) );
 369                 }
 370                 foreach ( $this->partitionQueues as $queue ) {
 371                         $queue->doFlushCaches();
 372                 }
 373         }
 374
 375         public function getAllQueuedJobs() {
 376                 $iterator = new AppendIterator();
 377                 foreach ( $this->partitionQueues as $queue ) {
 378                         $iterator->append( $queue->getAllQueuedJobs() );
 379                 }
 380                 return $iterator;
 381         }
 382
 383         public function getAllDelayedJobs() {
 384                 $iterator = new AppendIterator();
 385                 foreach ( $this->partitionQueues as $queue ) {
 386                         $iterator->append( $queue->getAllDelayedJobs() );
 387                 }
 388                 return $iterator;
 389         }
 390
 391         public function setTestingPrefix( $key ) {
 392                 foreach ( $this->partitionQueues as $queue ) {
 393                         $queue->setTestingPrefix( $key );
 394                 }
 395         }
 396
 397         /**
 398          * @return Array Map of (partition name => weight)
 399          */
 400         protected function getPartitionMap() {
 401                 $section = isset( $this->sectionsByWiki[$this->wiki] )
 402                         ? $this->sectionsByWiki[$this->wiki]
 403                         : 'default';
 404                 if ( !isset( $this->partitionsBySection[$section] ) ) {
 405                         throw new MWException( "No configuration for section '$section'." );
 406                 }
 407                 return $this->partitionsBySection[$section];
 408         }
 409
 410         /**
 411          * @return bool The queue is actually split up across multiple queue partitions
 412          */
 413         protected function isFederated() {
 414                 return ( count( $this->getPartitionMap() ) > 1 );
 415         }
 416
 417         /**
 418          * @return string
 419          */
 420         private function getCacheKey( $property ) {
 421                 list( $db, $prefix ) = wfSplitWikiID( $this->wiki );
 422                 return wfForeignMemcKey( $db, $prefix, 'jobqueue', $this->type, $property );
 423         }
 424 }