includes/job/JobQueueRedis.php

   1 <?php
   2 /**
   3  * Redis-backed job queue code.
   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 job queues stored in Redis
  26  *
  27  * This is faster, less resource intensive, queue that JobQueueDB.
  28  * All data for a queue using this class is placed into one redis server.
  29  *
  30  * There are eight main redis keys used to track jobs:
  31  *   - l-unclaimed  : A list of job IDs used for ready unclaimed jobs
  32  *   - z-claimed    : A sorted set of (job ID, UNIX timestamp as score) used for job retries
  33  *   - z-abandoned  : A sorted set of (job ID, UNIX timestamp as score) used for broken jobs
  34  *   - z-delayed    : A sorted set of (job ID, UNIX timestamp as score) used for delayed jobs
  35  *   - h-idBySha1   : A hash of (SHA1 => job ID) for unclaimed jobs used for de-duplication
  36  *   - h-sha1ById   : A hash of (job ID => SHA1) for unclaimed jobs used for de-duplication
  37  *   - h-attempts   : A hash of (job ID => attempt count) used for job claiming/retries
  38  *   - h-data       : A hash of (job ID => serialized blobs) for job storage
  39  * A job ID can be in only one of z-delayed, l-unclaimed, z-claimed, and z-abandoned.
  40  * If an ID appears in any of those lists, it should have a h-data entry for its ID.
  41  * If a job has a SHA1 de-duplication value and its ID is in l-unclaimed or z-delayed, then
  42  * there should be no other such jobs with that SHA1. Every h-idBySha1 entry has an h-sha1ById
  43  * entry and every h-sha1ById must refer to an ID that is l-unclaimed. If a job has its
  44  * ID in z-claimed or z-abandoned, then it must also have an h-attempts entry for its ID.
  45  *
  46  * Additionally, "rootjob:* keys track "root jobs" used for additional de-duplication.
  47  * Aside from root job keys, all keys have no expiry, and are only removed when jobs are run.
  48  * All the keys are prefixed with the relevant wiki ID information.
  49  *
  50  * This class requires Redis 2.6 as it makes use Lua scripts for fast atomic operations.
  51  * Additionally, it should be noted that redis has different persistence modes, such
  52  * as rdb snapshots, journaling, and no persistent. Appropriate configuration should be
  53  * made on the servers based on what queues are using it and what tolerance they have.
  54  *
  55  * @ingroup JobQueue
  56  * @ingroup Redis
  57  * @since 1.22
  58  */
  59 class JobQueueRedis extends JobQueue {
  60         /** @var RedisConnectionPool */
  61         protected $redisPool;
  62
  63         protected $server; // string; server address
  64         protected $compression; // string; compression method to use
  65
  66         const MAX_AGE_PRUNE = 604800; // integer; seconds a job can live once claimed (7 days)
  67
  68         protected $key; // string; key to prefix the queue keys with (used for testing)
  69
  70         /**
  71          * @params include:
  72          *   - redisConfig : An array of parameters to RedisConnectionPool::__construct().
  73          *                   Note that the serializer option is ignored "none" is always used.
  74          *   - redisServer : A hostname/port combination or the absolute path of a UNIX socket.
  75          *                   If a hostname is specified but no port, the standard port number
  76          *                   6379 will be used. Required.
  77          *   - compression : The type of compression to use; one of (none,gzip).
  78          * @param array $params
  79          */
  80         public function __construct( array $params ) {
  81                 parent::__construct( $params );
  82                 $params['redisConfig']['serializer'] = 'none'; // make it easy to use Lua
  83                 $this->server = $params['redisServer'];
  84                 $this->compression = isset( $params['compression'] ) ? $params['compression'] : 'none';
  85                 $this->redisPool = RedisConnectionPool::singleton( $params['redisConfig'] );
  86         }
  87
  88         protected function supportedOrders() {
  89                 return array( 'timestamp', 'fifo' );
  90         }
  91
  92         protected function optimalOrder() {
  93                 return 'fifo';
  94         }
  95
  96         protected function supportsDelayedJobs() {
  97                 return true;
  98         }
  99
 100         /**
 101          * @see JobQueue::doIsEmpty()
 102          * @return bool
 103          * @throws MWException
 104          */
 105         protected function doIsEmpty() {
 106                 return $this->doGetSize() == 0;
 107         }
 108
 109         /**
 110          * @see JobQueue::doGetSize()
 111          * @return integer
 112          * @throws MWException
 113          */
 114         protected function doGetSize() {
 115                 $conn = $this->getConnection();
 116                 try {
 117                         return $conn->lSize( $this->getQueueKey( 'l-unclaimed' ) );
 118                 } catch ( RedisException $e ) {
 119                         $this->throwRedisException( $this->server, $conn, $e );
 120                 }
 121         }
 122
 123         /**
 124          * @see JobQueue::doGetAcquiredCount()
 125          * @return integer
 126          * @throws MWException
 127          */
 128         protected function doGetAcquiredCount() {
 129                 if ( $this->claimTTL <= 0 ) {
 130                         return 0; // no acknowledgements
 131                 }
 132                 $conn = $this->getConnection();
 133                 try {
 134                         $conn->multi( Redis::PIPELINE );
 135                         $conn->zSize( $this->getQueueKey( 'z-claimed' ) );
 136                         $conn->zSize( $this->getQueueKey( 'z-abandoned' ) );
 137                         return array_sum( $conn->exec() );
 138                 } catch ( RedisException $e ) {
 139                         $this->throwRedisException( $this->server, $conn, $e );
 140                 }
 141         }
 142
 143         /**
 144          * @see JobQueue::doGetDelayedCount()
 145          * @return integer
 146          * @throws MWException
 147          */
 148         protected function doGetDelayedCount() {
 149                 if ( !$this->checkDelay ) {
 150                         return 0; // no delayed jobs
 151                 }
 152                 $conn = $this->getConnection();
 153                 try {
 154                         return $conn->zSize( $this->getQueueKey( 'z-delayed' ) );
 155                 } catch ( RedisException $e ) {
 156                         $this->throwRedisException( $this->server, $conn, $e );
 157                 }
 158         }
 159
 160         /**
 161          * @see JobQueue::doGetAbandonedCount()
 162          * @return integer
 163          * @throws MWException
 164          */
 165         protected function doGetAbandonedCount() {
 166                 if ( $this->claimTTL <= 0 ) {
 167                         return 0; // no acknowledgements
 168                 }
 169                 $conn = $this->getConnection();
 170                 try {
 171                         return $conn->zSize( $this->getQueueKey( 'z-abandoned' ) );
 172                 } catch ( RedisException $e ) {
 173                         $this->throwRedisException( $this->server, $conn, $e );
 174                 }
 175         }
 176
 177         /**
 178          * @see JobQueue::doBatchPush()
 179          * @param array $jobs
 180          * @param $flags
 181          * @return bool
 182          * @throws MWException
 183          */
 184         protected function doBatchPush( array $jobs, $flags ) {
 185                 // Convert the jobs into field maps (de-duplicated against each other)
 186                 $items = array(); // (job ID => job fields map)
 187                 foreach ( $jobs as $job ) {
 188                         $item = $this->getNewJobFields( $job );
 189                         if ( strlen( $item['sha1'] ) ) { // hash identifier => de-duplicate
 190                                 $items[$item['sha1']] = $item;
 191                         } else {
 192                                 $items[$item['uuid']] = $item;
 193                         }
 194                 }
 195
 196                 if ( !count( $items ) ) {
 197                         return true; // nothing to do
 198                 }
 199
 200                 $conn = $this->getConnection();
 201                 try {
 202                         // Actually push the non-duplicate jobs into the queue...
 203                         if ( $flags & self::QOS_ATOMIC ) {
 204                                 $batches = array( $items ); // all or nothing
 205                         } else {
 206                                 $batches = array_chunk( $items, 500 ); // avoid tying up the server
 207                         }
 208                         $failed = 0;
 209                         $pushed = 0;
 210                         foreach ( $batches as $itemBatch ) {
 211                                 $added = $this->pushBlobs( $conn, $itemBatch );
 212                                 if ( is_int( $added ) ) {
 213                                         $pushed += $added;
 214                                 } else {
 215                                         $failed += count( $itemBatch );
 216                                 }
 217                         }
 218                         if ( $failed > 0 ) {
 219                                 wfDebugLog( 'JobQueueRedis', "Could not insert {$failed} {$this->type} job(s)." );
 220                                 return false;
 221                         }
 222                         JobQueue::incrStats( 'job-insert', $this->type, count( $items ) );
 223                         JobQueue::incrStats( 'job-insert-duplicate', $this->type,
 224                                 count( $items ) - $failed - $pushed );
 225                 } catch ( RedisException $e ) {
 226                         $this->throwRedisException( $this->server, $conn, $e );
 227                 }
 228
 229                 return true;
 230         }
 231
 232         /**
 233          * @param RedisConnRef $conn
 234          * @param array $items List of results from JobQueueRedis::getNewJobFields()
 235          * @return integer Number of jobs inserted (duplicates are ignored)
 236          * @throws RedisException
 237          */
 238         protected function pushBlobs( RedisConnRef $conn, array $items ) {
 239                 $args = array(); // ([id, sha1, rtime, blob [, id, sha1, rtime, blob ... ] ] )
 240                 foreach ( $items as $item ) {
 241                         $args[] = (string)$item['uuid'];
 242                         $args[] = (string)$item['sha1'];
 243                         $args[] = (string)$item['rtimestamp'];
 244                         $args[] = (string)$this->serialize( $item );
 245                 }
 246                 static $script =
 247 <<<LUA
 248                 if #ARGV % 4 ~= 0 then return redis.error_reply('Unmatched arguments') end
 249                 local pushed = 0
 250                 for i = 1,#ARGV,4 do
 251                         local id,sha1,rtimestamp,blob = ARGV[i],ARGV[i+1],ARGV[i+2],ARGV[i+3]
 252                         if sha1 == '' or redis.call('hExists',KEYS[3],sha1) == 0 then
 253                                 if 1*rtimestamp > 0 then
 254                                         -- Insert into delayed queue (release time as score)
 255                                         redis.call('zAdd',KEYS[4],rtimestamp,id)
 256                                 else
 257                                         -- Insert into unclaimed queue
 258                                         redis.call('lPush',KEYS[1],id)
 259                                 end
 260                                 if sha1 ~= '' then
 261                                         redis.call('hSet',KEYS[2],id,sha1)
 262                                         redis.call('hSet',KEYS[3],sha1,id)
 263                                 end
 264                                 redis.call('hSet',KEYS[5],id,blob)
 265                                 pushed = pushed + 1
 266                         end
 267                 end
 268                 return pushed
 269 LUA;
 270                 return $conn->luaEval( $script,
 271                         array_merge(
 272                                 array(
 273                                         $this->getQueueKey( 'l-unclaimed' ), # KEYS[1]
 274                                         $this->getQueueKey( 'h-sha1ById' ), # KEYS[2]
 275                                         $this->getQueueKey( 'h-idBySha1' ), # KEYS[3]
 276                                         $this->getQueueKey( 'z-delayed' ), # KEYS[4]
 277                                         $this->getQueueKey( 'h-data' ), # KEYS[5]
 278                                 ),
 279                                 $args
 280                         ),
 281                         5 # number of first argument(s) that are keys
 282                 );
 283         }
 284
 285         /**
 286          * @see JobQueue::doPop()
 287          * @return Job|bool
 288          * @throws MWException
 289          */
 290         protected function doPop() {
 291                 $job = false;
 292
 293                 // Push ready delayed jobs into the queue every 10 jobs to spread the load.
 294                 // This is also done as a periodic task, but we don't want too much done at once.
 295                 if ( $this->checkDelay && mt_rand( 0, 9 ) == 0 ) {
 296                         $this->releaseReadyDelayedJobs();
 297                 }
 298
 299                 $conn = $this->getConnection();
 300                 try {
 301                         do {
 302                                 if ( $this->claimTTL > 0 ) {
 303                                         // Keep the claimed job list down for high-traffic queues
 304                                         if ( mt_rand( 0, 99 ) == 0 ) {
 305                                                 $this->recycleAndDeleteStaleJobs();
 306                                         }
 307                                         $blob = $this->popAndAcquireBlob( $conn );
 308                                 } else {
 309                                         $blob = $this->popAndDeleteBlob( $conn );
 310                                 }
 311                                 if ( $blob === false ) {
 312                                         break; // no jobs; nothing to do
 313                                 }
 314
 315                                 JobQueue::incrStats( 'job-pop', $this->type );
 316                                 $item = $this->unserialize( $blob );
 317                                 if ( $item === false ) {
 318                                         wfDebugLog( 'JobQueueRedis', "Could not unserialize {$this->type} job." );
 319                                         continue;
 320                                 }
 321
 322                                 // If $item is invalid, recycleAndDeleteStaleJobs() will cleanup as needed
 323                                 $job = $this->getJobFromFields( $item ); // may be false
 324                         } while ( !$job ); // job may be false if invalid
 325                 } catch ( RedisException $e ) {
 326                         $this->throwRedisException( $this->server, $conn, $e );
 327                 }
 328
 329                 return $job;
 330         }
 331
 332         /**
 333          * @param RedisConnRef $conn
 334          * @return array serialized string or false
 335          * @throws RedisException
 336          */
 337         protected function popAndDeleteBlob( RedisConnRef $conn ) {
 338                 static $script =
 339 <<<LUA
 340                 -- Pop an item off the queue
 341                 local id = redis.call('rpop',KEYS[1])
 342                 if not id then return false end
 343                 -- Get the job data and remove it
 344                 local item = redis.call('hGet',KEYS[4],id)
 345                 redis.call('hDel',KEYS[4],id)
 346                 -- Allow new duplicates of this job
 347                 local sha1 = redis.call('hGet',KEYS[2],id)
 348                 if sha1 then redis.call('hDel',KEYS[3],sha1) end
 349                 redis.call('hDel',KEYS[2],id)
 350                 -- Return the job data
 351                 return item
 352 LUA;
 353                 return $conn->luaEval( $script,
 354                         array(
 355                                 $this->getQueueKey( 'l-unclaimed' ), # KEYS[1]
 356                                 $this->getQueueKey( 'h-sha1ById' ), # KEYS[2]
 357                                 $this->getQueueKey( 'h-idBySha1' ), # KEYS[3]
 358                                 $this->getQueueKey( 'h-data' ), # KEYS[4]
 359                         ),
 360                         4 # number of first argument(s) that are keys
 361                 );
 362         }
 363
 364         /**
 365          * @param RedisConnRef $conn
 366          * @return array serialized string or false
 367          * @throws RedisException
 368          */
 369         protected function popAndAcquireBlob( RedisConnRef $conn ) {
 370                 static $script =
 371 <<<LUA
 372                 -- Pop an item off the queue
 373                 local id = redis.call('rPop',KEYS[1])
 374                 if not id then return false end
 375                 -- Allow new duplicates of this job
 376                 local sha1 = redis.call('hGet',KEYS[2],id)
 377                 if sha1 then redis.call('hDel',KEYS[3],sha1) end
 378                 redis.call('hDel',KEYS[2],id)
 379                 -- Mark the jobs as claimed and return it
 380                 redis.call('zAdd',KEYS[4],ARGV[1],id)
 381                 redis.call('hIncrBy',KEYS[5],id,1)
 382                 return redis.call('hGet',KEYS[6],id)
 383 LUA;
 384                 return $conn->luaEval( $script,
 385                         array(
 386                                 $this->getQueueKey( 'l-unclaimed' ), # KEYS[1]
 387                                 $this->getQueueKey( 'h-sha1ById' ), # KEYS[2]
 388                                 $this->getQueueKey( 'h-idBySha1' ), # KEYS[3]
 389                                 $this->getQueueKey( 'z-claimed' ), # KEYS[4]
 390                                 $this->getQueueKey( 'h-attempts' ), # KEYS[5]
 391                                 $this->getQueueKey( 'h-data' ), # KEYS[6]
 392                                 time(), # ARGV[1] (injected to be replication-safe)
 393                         ),
 394                         6 # number of first argument(s) that are keys
 395                 );
 396         }
 397
 398         /**
 399          * @see JobQueue::doAck()
 400          * @param Job $job
 401          * @return Job|bool
 402          * @throws MWException
 403          */
 404         protected function doAck( Job $job ) {
 405                 if ( !isset( $job->metadata['uuid'] ) ) {
 406                         throw new MWException( "Job of type '{$job->getType()}' has no UUID." );
 407                 }
 408                 if ( $this->claimTTL > 0 ) {
 409                         $conn = $this->getConnection();
 410                         try {
 411                                 static $script =
 412 <<<LUA
 413                                 -- Unmark the job as claimed
 414                                 redis.call('zRem',KEYS[1],ARGV[1])
 415                                 redis.call('hDel',KEYS[2],ARGV[1])
 416                                 -- Delete the job data itself
 417                                 return redis.call('hDel',KEYS[3],ARGV[1])
 418 LUA;
 419                                 $res = $conn->luaEval( $script,
 420                                         array(
 421                                                 $this->getQueueKey( 'z-claimed' ), # KEYS[1]
 422                                                 $this->getQueueKey( 'h-attempts' ), # KEYS[2]
 423                                                 $this->getQueueKey( 'h-data' ), # KEYS[3]
 424                                                 $job->metadata['uuid'] # ARGV[1]
 425                                         ),
 426                                         3 # number of first argument(s) that are keys
 427                                 );
 428
 429                                 if ( !$res ) {
 430                                         wfDebugLog( 'JobQueueRedis', "Could not acknowledge {$this->type} job." );
 431                                         return false;
 432                                 }
 433                         } catch ( RedisException $e ) {
 434                                 $this->throwRedisException( $this->server, $conn, $e );
 435                         }
 436                 }
 437                 return true;
 438         }
 439
 440         /**
 441          * @see JobQueue::doDeduplicateRootJob()
 442          * @param Job $job
 443          * @return bool
 444          * @throws MWException
 445          */
 446         protected function doDeduplicateRootJob( Job $job ) {
 447                 if ( !$job->hasRootJobParams() ) {
 448                         throw new MWException( "Cannot register root job; missing parameters." );
 449                 }
 450                 $params = $job->getRootJobParams();
 451
 452                 $key = $this->getRootJobCacheKey( $params['rootJobSignature'] );
 453
 454                 $conn = $this->getConnection();
 455                 try {
 456                         $timestamp = $conn->get( $key ); // current last timestamp of this job
 457                         if ( $timestamp && $timestamp >= $params['rootJobTimestamp'] ) {
 458                                 return true; // a newer version of this root job was enqueued
 459                         }
 460                         // Update the timestamp of the last root job started at the location...
 461                         return $conn->set( $key, $params['rootJobTimestamp'], self::ROOTJOB_TTL ); // 2 weeks
 462                 } catch ( RedisException $e ) {
 463                         $this->throwRedisException( $this->server, $conn, $e );
 464                 }
 465         }
 466
 467         /**
 468          * @see JobQueue::doIsRootJobOldDuplicate()
 469          * @param Job $job
 470          * @return bool
 471          */
 472         protected function doIsRootJobOldDuplicate( Job $job ) {
 473                 if ( !$job->hasRootJobParams() ) {
 474                         return false; // job has no de-deplication info
 475                 }
 476                 $params = $job->getRootJobParams();
 477
 478                 $conn = $this->getConnection();
 479                 try {
 480                         // Get the last time this root job was enqueued
 481                         $timestamp = $conn->get( $this->getRootJobCacheKey( $params['rootJobSignature'] ) );
 482                 } catch ( RedisException $e ) {
 483                         $this->throwRedisException( $this->server, $conn, $e );
 484                 }
 485
 486                 // Check if a new root job was started at the location after this one's...
 487                 return ( $timestamp && $timestamp > $params['rootJobTimestamp'] );
 488         }
 489
 490         /**
 491          * @see JobQueue::doDelete()
 492          * @return bool
 493          */
 494         protected function doDelete() {
 495                 static $props = array( 'l-unclaimed', 'z-claimed', 'z-abandoned',
 496                         'z-delayed', 'h-idBySha1', 'h-sha1ById', 'h-attempts', 'h-data' );
 497
 498                 $conn = $this->getConnection();
 499                 try {
 500                         $keys = array();
 501                         foreach ( $props as $prop ) {
 502                                 $keys[] = $this->getQueueKey( $prop );
 503                         }
 504                         return ( $conn->delete( $keys ) !== false );
 505                 } catch ( RedisException $e ) {
 506                         $this->throwRedisException( $this->server, $conn, $e );
 507                 }
 508         }
 509
 510         /**
 511          * @see JobQueue::getAllQueuedJobs()
 512          * @return Iterator
 513          */
 514         public function getAllQueuedJobs() {
 515                 $conn = $this->getConnection();
 516                 try {
 517                         $that = $this;
 518                         return new MappedIterator(
 519                                 $conn->lRange( $this->getQueueKey( 'l-unclaimed' ), 0, -1 ),
 520                                 function( $uid ) use ( $that, $conn ) {
 521                                         return $that->getJobFromUidInternal( $uid, $conn );
 522                                 },
 523                                 array( 'accept' => function ( $job ) { return is_object( $job ); } )
 524                         );
 525                 } catch ( RedisException $e ) {
 526                         $this->throwRedisException( $this->server, $conn, $e );
 527                 }
 528         }
 529
 530         /**
 531          * @see JobQueue::getAllQueuedJobs()
 532          * @return Iterator
 533          */
 534         public function getAllDelayedJobs() {
 535                 $conn = $this->getConnection();
 536                 try {
 537                         $that = $this;
 538                         return new MappedIterator( // delayed jobs
 539                                 $conn->zRange( $this->getQueueKey( 'z-delayed' ), 0, -1 ),
 540                                 function( $uid ) use ( $that, $conn ) {
 541                                         return $that->getJobFromUidInternal( $uid, $conn );
 542                                 },
 543                                 array( 'accept' => function ( $job ) { return is_object( $job ); } )
 544                         );
 545                 } catch ( RedisException $e ) {
 546                         $this->throwRedisException( $this->server, $conn, $e );
 547                 }
 548         }
 549
 550         public function getCoalesceLocationInternal() {
 551                 return "RedisServer:" . $this->server;
 552         }
 553
 554         protected function doGetSiblingQueuesWithJobs( array $types ) {
 555                 return array_keys( array_filter( $this->doGetSiblingQueueSizes( $types ) ) );
 556         }
 557
 558         protected function doGetSiblingQueueSizes( array $types ) {
 559                 $sizes = array(); // (type => size)
 560                 $types = array_values( $types ); // reindex
 561                 try {
 562                         $conn = $this->getConnection();
 563                         $conn->multi( Redis::PIPELINE );
 564                         foreach ( $types as $type ) {
 565                                 $conn->lSize( $this->getQueueKey( 'l-unclaimed', $type ) );
 566                         }
 567                         $res = $conn->exec();
 568                         if ( is_array( $res ) ) {
 569                                 foreach ( $res as $i => $size ) {
 570                                         $sizes[$types[$i]] = $size;
 571                                 }
 572                         }
 573                 } catch ( RedisException $e ) {
 574                         $this->throwRedisException( $this->server, $conn, $e );
 575                 }
 576                 return $sizes;
 577         }
 578
 579         /**
 580          * This function should not be called outside JobQueueRedis
 581          *
 582          * @param $uid string
 583          * @param $conn RedisConnRef
 584          * @return Job|bool Returns false if the job does not exist
 585          * @throws MWException
 586          */
 587         public function getJobFromUidInternal( $uid, RedisConnRef $conn ) {
 588                 try {
 589                         $data = $conn->hGet( $this->getQueueKey( 'h-data' ), $uid );
 590                         if ( $data === false ) {
 591                                 return false; // not found
 592                         }
 593                         $item = $this->unserialize( $conn->hGet( $this->getQueueKey( 'h-data' ), $uid ) );
 594                         if ( !is_array( $item ) ) { // this shouldn't happen
 595                                 throw new MWException( "Could not find job with ID '$uid'." );
 596                         }
 597                         $title = Title::makeTitle( $item['namespace'], $item['title'] );
 598                         $job = Job::factory( $item['type'], $title, $item['params'] );
 599                         $job->metadata['uuid'] = $item['uuid'];
 600                         return $job;
 601                 } catch ( RedisException $e ) {
 602                         $this->throwRedisException( $this->server, $conn, $e );
 603                 }
 604         }
 605
 606         /**
 607          * Release any ready delayed jobs into the queue
 608          *
 609          * @return integer Number of jobs released
 610          * @throws MWException
 611          */
 612         public function releaseReadyDelayedJobs() {
 613                 $count = 0;
 614
 615                 $conn = $this->getConnection();
 616                 try {
 617                         static $script =
 618 <<<LUA
 619                         -- Get the list of ready delayed jobs, sorted by readiness
 620                         local ids = redis.call('zRangeByScore',KEYS[1],0,ARGV[1])
 621                         -- Migrate the jobs from the "delayed" set to the "unclaimed" list
 622                         for k,id in ipairs(ids) do
 623                                 redis.call('lPush',KEYS[2],id)
 624                                 redis.call('zRem',KEYS[1],id)
 625                         end
 626                         return #ids
 627 LUA;
 628                         $count += (int)$conn->luaEval( $script,
 629                                 array(
 630                                         $this->getQueueKey( 'z-delayed' ), // KEYS[1]
 631                                         $this->getQueueKey( 'l-unclaimed' ), // KEYS[2]
 632                                         time() // ARGV[1]; max "delay until" UNIX timestamp
 633                                 ),
 634                                 2 # first two arguments are keys
 635                         );
 636                 } catch ( RedisException $e ) {
 637                         $this->throwRedisException( $this->server, $conn, $e );
 638                 }
 639
 640                 return $count;
 641         }
 642
 643         /**
 644          * Recycle or destroy any jobs that have been claimed for too long
 645          *
 646          * @return integer Number of jobs recycled/deleted
 647          * @throws MWException
 648          */
 649         public function recycleAndDeleteStaleJobs() {
 650                 if ( $this->claimTTL <= 0 ) { // sanity
 651                         throw new MWException( "Cannot recycle jobs since acknowledgements are disabled." );
 652                 }
 653                 $count = 0;
 654                 // For each job item that can be retried, we need to add it back to the
 655                 // main queue and remove it from the list of currenty claimed job items.
 656                 // For those that cannot, they are marked as dead and kept around for
 657                 // investigation and manual job restoration but are eventually deleted.
 658                 $conn = $this->getConnection();
 659                 try {
 660                         $now = time();
 661                         static $script =
 662 <<<LUA
 663                         local released,abandoned,pruned = 0,0,0
 664                         -- Get all non-dead jobs that have an expired claim on them.
 665                         -- The score for each item is the last claim timestamp (UNIX).
 666                         local staleClaims = redis.call('zRangeByScore',KEYS[1],0,ARGV[1])
 667                         for k,id in ipairs(staleClaims) do
 668                                 local timestamp = redis.call('zScore',KEYS[1],id)
 669                                 local attempts = redis.call('hGet',KEYS[2],id)
 670                                 if attempts < ARGV[3] then
 671                                         -- Claim expired and retries left: re-enqueue the job
 672                                         redis.call('lPush',KEYS[3],id)
 673                                         redis.call('hIncrBy',KEYS[2],id,1)
 674                                         released = released + 1
 675                                 else
 676                                         -- Claim expired and no retries left: mark the job as dead
 677                                         redis.call('zAdd',KEYS[5],timestamp,id)
 678                                         abandoned = abandoned + 1
 679                                 end
 680                                 redis.call('zRem',KEYS[1],id)
 681                         end
 682                         -- Get all of the dead jobs that have been marked as dead for too long.
 683                         -- The score for each item is the last claim timestamp (UNIX).
 684                         local deadClaims = redis.call('zRangeByScore',KEYS[5],0,ARGV[2])
 685                         for k,id in ipairs(deadClaims) do
 686                                 -- Stale and out of retries: remove any traces of the job
 687                                 redis.call('zRem',KEYS[5],id)
 688                                 redis.call('hDel',KEYS[2],id)
 689                                 redis.call('hDel',KEYS[4],id)
 690                                 pruned = pruned + 1
 691                         end
 692                         return {released,abandoned,pruned}
 693 LUA;
 694                         $res = $conn->luaEval( $script,
 695                                 array(
 696                                         $this->getQueueKey( 'z-claimed' ), # KEYS[1]
 697                                         $this->getQueueKey( 'h-attempts' ), # KEYS[2]
 698                                         $this->getQueueKey( 'l-unclaimed' ), # KEYS[3]
 699                                         $this->getQueueKey( 'h-data' ), # KEYS[4]
 700                                         $this->getQueueKey( 'z-abandoned' ), # KEYS[5]
 701                                         $now - $this->claimTTL, # ARGV[1]
 702                                         $now - self::MAX_AGE_PRUNE, # ARGV[2]
 703                                         $this->maxTries # ARGV[3]
 704                                 ),
 705                                 5 # number of first argument(s) that are keys
 706                         );
 707                         if ( $res ) {
 708                                 list( $released, $abandoned, $pruned ) = $res;
 709                                 $count += $released + $pruned;
 710                                 JobQueue::incrStats( 'job-recycle', $this->type, $released );
 711                                 JobQueue::incrStats( 'job-abandon', $this->type, $abandoned );
 712                         }
 713                 } catch ( RedisException $e ) {
 714                         $this->throwRedisException( $this->server, $conn, $e );
 715                 }
 716
 717                 return $count;
 718         }
 719
 720         /**
 721          * @return Array
 722          */
 723         protected function doGetPeriodicTasks() {
 724                 $tasks = array();
 725                 if ( $this->claimTTL > 0 ) {
 726                         $tasks['recycleAndDeleteStaleJobs'] = array(
 727                                 'callback' => array( $this, 'recycleAndDeleteStaleJobs' ),
 728                                 'period' => ceil( $this->claimTTL / 2 )
 729                         );
 730                 }
 731                 if ( $this->checkDelay ) {
 732                         $tasks['releaseReadyDelayedJobs'] = array(
 733                                 'callback' => array( $this, 'releaseReadyDelayedJobs' ),
 734                                 'period' => 300 // 5 minutes
 735                         );
 736                 }
 737                 return $tasks;
 738         }
 739
 740         /**
 741          * @param $job Job
 742          * @return array
 743          */
 744         protected function getNewJobFields( Job $job ) {
 745                 return array(
 746                         // Fields that describe the nature of the job
 747                         'type'       => $job->getType(),
 748                         'namespace'  => $job->getTitle()->getNamespace(),
 749                         'title'      => $job->getTitle()->getDBkey(),
 750                         'params'     => $job->getParams(),
 751                         // Some jobs cannot run until a "release timestamp"
 752                         'rtimestamp' => $job->getReleaseTimestamp() ?: 0,
 753                         // Additional job metadata
 754                         'uuid'       => UIDGenerator::newRawUUIDv4( UIDGenerator::QUICK_RAND ),
 755                         'sha1'       => $job->ignoreDuplicates()
 756                                 ? wfBaseConvert( sha1( serialize( $job->getDeduplicationInfo() ) ), 16, 36, 31 )
 757                                 : '',
 758                         'timestamp'  => time() // UNIX timestamp
 759                 );
 760         }
 761
 762         /**
 763          * @param $fields array
 764          * @return Job|bool
 765          */
 766         protected function getJobFromFields( array $fields ) {
 767                 $title = Title::makeTitleSafe( $fields['namespace'], $fields['title'] );
 768                 if ( $title ) {
 769                         $job = Job::factory( $fields['type'], $title, $fields['params'] );
 770                         $job->metadata['uuid'] = $fields['uuid'];
 771                         return $job;
 772                 }
 773                 return false;
 774         }
 775
 776         /**
 777          * @param array $fields
 778          * @return string Serialized and possibly compressed version of $fields
 779          */
 780         protected function serialize( array $fields ) {
 781                 $blob = serialize( $fields );
 782                 if ( $this->compression === 'gzip'
 783                         && strlen( $blob ) >= 1024 && function_exists( 'gzdeflate' ) )
 784                 {
 785                         $object = (object)array( 'blob' => gzdeflate( $blob ), 'enc' => 'gzip' );
 786                         $blobz = serialize( $object );
 787                         return ( strlen( $blobz ) < strlen( $blob ) ) ? $blobz : $blob;
 788                 } else {
 789                         return $blob;
 790                 }
 791         }
 792
 793         /**
 794          * @param string $blob
 795          * @return array|bool Unserialized version of $blob or false
 796          */
 797         protected function unserialize( $blob ) {
 798                 $fields = unserialize( $blob );
 799                 if ( is_object( $fields ) ) {
 800                         if ( $fields->enc === 'gzip' && function_exists( 'gzinflate' ) ) {
 801                                 $fields = unserialize( gzinflate( $fields->blob ) );
 802                         } else {
 803                                 $fields = false;
 804                         }
 805                 }
 806                 return is_array( $fields ) ? $fields : false;
 807         }
 808
 809         /**
 810          * Get a connection to the server that handles all sub-queues for this queue
 811          *
 812          * @return Array (server name, Redis instance)
 813          * @throws MWException
 814          */
 815         protected function getConnection() {
 816                 $conn = $this->redisPool->getConnection( $this->server );
 817                 if ( !$conn ) {
 818                         throw new JobQueueConnectionError( "Unable to connect to redis server." );
 819                 }
 820                 return $conn;
 821         }
 822
 823         /**
 824          * @param $server string
 825          * @param $conn RedisConnRef
 826          * @param $e RedisException
 827          * @throws MWException
 828          */
 829         protected function throwRedisException( $server, RedisConnRef $conn, $e ) {
 830                 $this->redisPool->handleException( $server, $conn, $e );
 831                 throw new JobQueueError( "Redis server error: {$e->getMessage()}\n" );
 832         }
 833
 834         /**
 835          * @param $prop string
 836          * @param $type string|null
 837          * @return string
 838          */
 839         private function getQueueKey( $prop, $type = null ) {
 840                 $type = is_string( $type ) ? $type : $this->type;
 841                 list( $db, $prefix ) = wfSplitWikiID( $this->wiki );
 842                 if ( strlen( $this->key ) ) { // namespaced queue (for testing)
 843                         return wfForeignMemcKey( $db, $prefix, 'jobqueue', $type, $this->key, $prop );
 844                 } else {
 845                         return wfForeignMemcKey( $db, $prefix, 'jobqueue', $type, $prop );
 846                 }
 847         }
 848
 849         /**
 850          * @param $key string
 851          * @return void
 852          */
 853         public function setTestingPrefix( $key ) {
 854                 $this->key = $key;
 855         }
 856 }