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 1.21
  58  */
  59 class JobQueueRedis extends JobQueue {
  60         /** @var RedisConnectionPool */
  61         protected $redisPool;
  62
  63         protected $server; // string; server address
  64
  65         const MAX_AGE_PRUNE = 604800; // integer; seconds a job can live once claimed (7 days)
  66
  67         protected $key; // string; key to prefix the queue keys with (used for testing)
  68
  69         /**
  70          * @params include:
  71          *   - redisConfig : An array of parameters to RedisConnectionPool::__construct().
  72          *                   Note that the serializer option is ignored "none" is always used.
  73          *   - redisServer : A hostname/port combination or the absolute path of a UNIX socket.
  74          *                   If a hostname is specified but no port, the standard port number
  75          *                   6379 will be used. Required.
  76          * @param array $params
  77          */
  78         public function __construct( array $params ) {
  79                 parent::__construct( $params );
  80                 $params['redisConfig']['serializer'] = 'none'; // make it easy to use Lua
  81                 $this->server = $params['redisServer'];
  82                 $this->redisPool = RedisConnectionPool::singleton( $params['redisConfig'] );
  83         }
  84
  85         protected function supportedOrders() {
  86                 return array( 'timestamp', 'fifo' );
  87         }
  88
  89         protected function optimalOrder() {
  90                 return 'fifo';
  91         }
  92
  93         protected function supportsDelayedJobs() {
  94                 return true;
  95         }
  96
  97         /**
  98          * @see JobQueue::doIsEmpty()
  99          * @return bool
 100          * @throws MWException
 101          */
 102         protected function doIsEmpty() {
 103                 return $this->doGetSize() == 0;
 104         }
 105
 106         /**
 107          * @see JobQueue::doGetSize()
 108          * @return integer
 109          * @throws MWException
 110          */
 111         protected function doGetSize() {
 112                 $conn = $this->getConnection();
 113                 try {
 114                         return $conn->lSize( $this->getQueueKey( 'l-unclaimed' ) );
 115                 } catch ( RedisException $e ) {
 116                         $this->throwRedisException( $this->server, $conn, $e );
 117                 }
 118         }
 119
 120         /**
 121          * @see JobQueue::doGetAcquiredCount()
 122          * @return integer
 123          * @throws MWException
 124          */
 125         protected function doGetAcquiredCount() {
 126                 if ( $this->claimTTL <= 0 ) {
 127                         return 0; // no acknowledgements
 128                 }
 129                 $conn = $this->getConnection();
 130                 try {
 131                         $conn->multi( Redis::PIPELINE );
 132                         $conn->zSize( $this->getQueueKey( 'z-claimed' ) );
 133                         $conn->zSize( $this->getQueueKey( 'z-abandoned' ) );
 134                         return array_sum( $conn->exec() );
 135                 } catch ( RedisException $e ) {
 136                         $this->throwRedisException( $this->server, $conn, $e );
 137                 }
 138         }
 139
 140         /**
 141          * @see JobQueue::doGetDelayedCount()
 142          * @return integer
 143          * @throws MWException
 144          */
 145         protected function doGetDelayedCount() {
 146                 if ( !$this->checkDelay ) {
 147                         return 0; // no delayed jobs
 148                 }
 149                 $conn = $this->getConnection();
 150                 try {
 151                         return $conn->zSize( $this->getQueueKey( 'z-delayed' ) );
 152                 } catch ( RedisException $e ) {
 153                         $this->throwRedisException( $this->server, $conn, $e );
 154                 }
 155         }
 156
 157         /**
 158          * @see JobQueue::doBatchPush()
 159          * @param array $jobs
 160          * @param $flags
 161          * @return bool
 162          * @throws MWException
 163          */
 164         protected function doBatchPush( array $jobs, $flags ) {
 165                 // Convert the jobs into field maps (de-duplicated against each other)
 166                 $items = array(); // (job ID => job fields map)
 167                 foreach ( $jobs as $job ) {
 168                         $item = $this->getNewJobFields( $job );
 169                         if ( strlen( $item['sha1'] ) ) { // hash identifier => de-duplicate
 170                                 $items[$item['sha1']] = $item;
 171                         } else {
 172                                 $items[$item['uuid']] = $item;
 173                         }
 174                 }
 175
 176                 if ( !count( $items ) ) {
 177                         return true; // nothing to do
 178                 }
 179
 180                 $conn = $this->getConnection();
 181                 try {
 182                         // Actually push the non-duplicate jobs into the queue...
 183                         if ( $flags & self::QoS_Atomic ) {
 184                                 $batches = array( $items ); // all or nothing
 185                         } else {
 186                                 $batches = array_chunk( $items, 500 ); // avoid tying up the server
 187                         }
 188                         $failed = 0;
 189                         $pushed = 0;
 190                         foreach ( $batches as $itemBatch ) {
 191                                 $added = $this->pushBlobs( $conn, $itemBatch );
 192                                 if ( is_int( $added ) ) {
 193                                         $pushed += $added;
 194                                 } else {
 195                                         $failed += count( $itemBatch );
 196                                 }
 197                         }
 198                         if ( $failed > 0 ) {
 199                                 wfDebugLog( 'JobQueueRedis', "Could not insert {$failed} {$this->type} job(s)." );
 200                                 return false;
 201                         }
 202                         wfIncrStats( 'job-insert', count( $items ) );
 203                         wfIncrStats( 'job-insert-duplicate', count( $items ) - $failed - $pushed );
 204                 } catch ( RedisException $e ) {
 205                         $this->throwRedisException( $this->server, $conn, $e );
 206                 }
 207
 208                 return true;
 209         }
 210
 211         /**
 212          * @param RedisConnRef $conn
 213          * @param array $items List of results from JobQueueRedis::getNewJobFields()
 214          * @return integer Number of jobs inserted (duplicates are ignored)
 215          * @throws RedisException
 216          */
 217         protected function pushBlobs( RedisConnRef $conn, array $items ) {
 218                 $args = array(); // ([id, sha1, blob [, id, sha1, blob ... ] ] )
 219                 foreach ( $items as $item ) {
 220                         $args[] = (string)$item['uuid'];
 221                         $args[] = (string)$item['sha1'];
 222                         $args[] = (string)$item['rtimestamp'];
 223                         $args[] = (string)serialize( $item );
 224                 }
 225                 static $script =
 226 <<<LUA
 227                 if #ARGV % 4 ~= 0 then return redis.error_reply('Unmatched arguments') end
 228                 local pushed = 0
 229                 for i = 1,#ARGV,4 do
 230                         local id,sha1,rtimestamp,blob = ARGV[i],ARGV[i+1],ARGV[i+2],ARGV[i+3]
 231                         if sha1 == '' or redis.call('hExists',KEYS[3],sha1) == 0 then
 232                                 if 1*rtimestamp > 0 then
 233                                         -- Insert into delayed queue (release time as score)
 234                                         redis.call('zAdd',KEYS[4],rtimestamp,id)
 235                                 else
 236                                         -- Insert into unclaimed queue
 237                                         redis.call('lPush',KEYS[1],id)
 238                                 end
 239                                 if sha1 ~= '' then
 240                                         redis.call('hSet',KEYS[2],id,sha1)
 241                                         redis.call('hSet',KEYS[3],sha1,id)
 242                                 end
 243                                 redis.call('hSet',KEYS[5],id,blob)
 244                                 pushed = pushed + 1
 245                         end
 246                 end
 247                 return pushed
 248 LUA;
 249                 return $this->redisEval( $conn, $script,
 250                         array_merge(
 251                                 array(
 252                                         $this->getQueueKey( 'l-unclaimed' ), # KEYS[1]
 253                                         $this->getQueueKey( 'h-sha1ById' ), # KEYS[2]
 254                                         $this->getQueueKey( 'h-idBySha1' ), # KEYS[3]
 255                                         $this->getQueueKey( 'z-delayed' ), # KEYS[4]
 256                                         $this->getQueueKey( 'h-data' ), # KEYS[5]
 257                                 ),
 258                                 $args
 259                         ),
 260                         5 # number of first argument(s) that are keys
 261                 );
 262         }
 263
 264         /**
 265          * @see JobQueue::doPop()
 266          * @return Job|bool
 267          * @throws MWException
 268          */
 269         protected function doPop() {
 270                 $job = false;
 271
 272                 // Push ready delayed jobs into the queue every 10 jobs to spread the load.
 273                 // This is also done as a periodic task, but we don't want too much done at once.
 274                 if ( $this->checkDelay && mt_rand( 0, 9 ) == 0 ) {
 275                         $this->releaseReadyDelayedJobs();
 276                 }
 277
 278                 $conn = $this->getConnection();
 279                 try {
 280                         do {
 281                                 if ( $this->claimTTL > 0 ) {
 282                                         // Keep the claimed job list down for high-traffic queues
 283                                         if ( mt_rand( 0, 99 ) == 0 ) {
 284                                                 $this->recycleAndDeleteStaleJobs();
 285                                         }
 286                                         $blob = $this->popAndAcquireBlob( $conn );
 287                                 } else {
 288                                         $blob = $this->popAndDeleteBlob( $conn );
 289                                 }
 290                                 if ( $blob === false ) {
 291                                         break; // no jobs; nothing to do
 292                                 }
 293
 294                                 wfIncrStats( 'job-pop' );
 295                                 $item = unserialize( $blob );
 296                                 if ( $item === false ) {
 297                                         wfDebugLog( 'JobQueueRedis', "Could not unserialize {$this->type} job." );
 298                                         continue;
 299                                 }
 300
 301                                 // If $item is invalid, recycleAndDeleteStaleJobs() will cleanup as needed
 302                                 $job = $this->getJobFromFields( $item ); // may be false
 303                         } while ( !$job ); // job may be false if invalid
 304                 } catch ( RedisException $e ) {
 305                         $this->throwRedisException( $this->server, $conn, $e );
 306                 }
 307
 308                 return $job;
 309         }
 310
 311         /**
 312          * @param RedisConnRef $conn
 313          * @return array serialized string or false
 314          * @throws RedisException
 315          */
 316         protected function popAndDeleteBlob( RedisConnRef $conn ) {
 317                 static $script =
 318 <<<LUA
 319                 -- Pop an item off the queue
 320                 local id = redis.call('rpop',KEYS[1])
 321                 if not id then return false end
 322                 -- Get the job data and remove it
 323                 local item = redis.call('hGet',KEYS[4],id)
 324                 redis.call('hDel',KEYS[4],id)
 325                 -- Allow new duplicates of this job
 326                 local sha1 = redis.call('hGet',KEYS[2],id)
 327                 if sha1 then redis.call('hDel',KEYS[3],sha1) end
 328                 redis.call('hDel',KEYS[2],id)
 329                 -- Return the job data
 330                 return item
 331 LUA;
 332                 return $this->redisEval( $conn, $script,
 333                         array(
 334                                 $this->getQueueKey( 'l-unclaimed' ), # KEYS[1]
 335                                 $this->getQueueKey( 'h-sha1ById' ), # KEYS[2]
 336                                 $this->getQueueKey( 'h-idBySha1' ), # KEYS[3]
 337                                 $this->getQueueKey( 'h-data' ), # KEYS[4]
 338                         ),
 339                         4 # number of first argument(s) that are keys
 340                 );
 341         }
 342
 343         /**
 344          * @param RedisConnRef $conn
 345          * @return array serialized string or false
 346          * @throws RedisException
 347          */
 348         protected function popAndAcquireBlob( RedisConnRef $conn ) {
 349                 static $script =
 350 <<<LUA
 351                 -- Pop an item off the queue
 352                 local id = redis.call('rPop',KEYS[1])
 353                 if not id then return false end
 354                 -- Allow new duplicates of this job
 355                 local sha1 = redis.call('hGet',KEYS[2],id)
 356                 if sha1 then redis.call('hDel',KEYS[3],sha1) end
 357                 redis.call('hDel',KEYS[2],id)
 358                 -- Mark the jobs as claimed and return it
 359                 redis.call('zAdd',KEYS[4],ARGV[1],id)
 360                 redis.call('hIncrBy',KEYS[5],id,1)
 361                 return redis.call('hGet',KEYS[6],id)
 362 LUA;
 363                 return $this->redisEval( $conn, $script,
 364                         array(
 365                                 $this->getQueueKey( 'l-unclaimed' ), # KEYS[1]
 366                                 $this->getQueueKey( 'h-sha1ById' ), # KEYS[2]
 367                                 $this->getQueueKey( 'h-idBySha1' ), # KEYS[3]
 368                                 $this->getQueueKey( 'z-claimed' ), # KEYS[4]
 369                                 $this->getQueueKey( 'h-attempts' ), # KEYS[5]
 370                                 $this->getQueueKey( 'h-data' ), # KEYS[6]
 371                                 time(), # ARGV[1] (injected to be replication-safe)
 372                         ),
 373                         6 # number of first argument(s) that are keys
 374                 );
 375         }
 376
 377         /**
 378          * @see JobQueue::doAck()
 379          * @param Job $job
 380          * @return Job|bool
 381          * @throws MWException
 382          */
 383         protected function doAck( Job $job ) {
 384                 if ( $this->claimTTL > 0 ) {
 385                         $conn = $this->getConnection();
 386                         try {
 387                                 // Get the exact field map this Job came from, regardless of whether
 388                                 // the job was transformed into a DuplicateJob or anything of the sort.
 389                                 $item = $job->metadata['sourceFields'];
 390
 391                                 static $script =
 392 <<<LUA
 393                                 -- Unmark the job as claimed
 394                                 redis.call('zRem',KEYS[1],ARGV[1])
 395                                 redis.call('hDel',KEYS[2],ARGV[1])
 396                                 -- Delete the job data itself
 397                                 return redis.call('hDel',KEYS[3],ARGV[1])
 398 LUA;
 399                                 $res = $this->redisEval( $conn, $script,
 400                                         array(
 401                                                 $this->getQueueKey( 'z-claimed' ), # KEYS[1]
 402                                                 $this->getQueueKey( 'h-attempts' ), # KEYS[2]
 403                                                 $this->getQueueKey( 'h-data' ), # KEYS[3]
 404                                                 $item['uuid'] # ARGV[1]
 405                                         ),
 406                                         3 # number of first argument(s) that are keys
 407                                 );
 408
 409                                 if ( !$res ) {
 410                                         wfDebugLog( 'JobQueueRedis', "Could not acknowledge {$this->type} job." );
 411                                         return false;
 412                                 }
 413                         } catch ( RedisException $e ) {
 414                                 $this->throwRedisException( $this->server, $conn, $e );
 415                         }
 416                 }
 417                 return true;
 418         }
 419
 420         /**
 421          * @see JobQueue::doDeduplicateRootJob()
 422          * @param Job $job
 423          * @return bool
 424          * @throws MWException
 425          */
 426         protected function doDeduplicateRootJob( Job $job ) {
 427                 $params = $job->getParams();
 428                 if ( !isset( $params['rootJobSignature'] ) ) {
 429                         throw new MWException( "Cannot register root job; missing 'rootJobSignature'." );
 430                 } elseif ( !isset( $params['rootJobTimestamp'] ) ) {
 431                         throw new MWException( "Cannot register root job; missing 'rootJobTimestamp'." );
 432                 }
 433                 $key = $this->getRootJobCacheKey( $params['rootJobSignature'] );
 434
 435                 $conn = $this->getConnection();
 436                 try {
 437                         $timestamp = $conn->get( $key ); // current last timestamp of this job
 438                         if ( $timestamp && $timestamp >= $params['rootJobTimestamp'] ) {
 439                                 return true; // a newer version of this root job was enqueued
 440                         }
 441                         // Update the timestamp of the last root job started at the location...
 442                         return $conn->set( $key, $params['rootJobTimestamp'], self::ROOTJOB_TTL ); // 2 weeks
 443                 } catch ( RedisException $e ) {
 444                         $this->throwRedisException( $this->server, $conn, $e );
 445                 }
 446         }
 447
 448         /**
 449          * @see JobQueue::doIsRootJobOldDuplicate()
 450          * @param Job $job
 451          * @return bool
 452          */
 453         protected function doIsRootJobOldDuplicate( Job $job ) {
 454                 $params = $job->getParams();
 455                 if ( !isset( $params['rootJobSignature'] ) ) {
 456                         return false; // job has no de-deplication info
 457                 } elseif ( !isset( $params['rootJobTimestamp'] ) ) {
 458                         wfDebugLog( 'JobQueueRedis', "Cannot check root job; missing 'rootJobTimestamp'." );
 459                         return false;
 460                 }
 461
 462                 $conn = $this->getConnection();
 463                 try {
 464                         // Get the last time this root job was enqueued
 465                         $timestamp = $conn->get( $this->getRootJobCacheKey( $params['rootJobSignature'] ) );
 466                 } catch ( RedisException $e ) {
 467                         $this->throwRedisException( $this->server, $conn, $e );
 468                 }
 469
 470                 // Check if a new root job was started at the location after this one's...
 471                 return ( $timestamp && $timestamp > $params['rootJobTimestamp'] );
 472         }
 473
 474         /**
 475          * @see JobQueue::getAllQueuedJobs()
 476          * @return Iterator
 477          */
 478         public function getAllQueuedJobs() {
 479                 $conn = $this->getConnection();
 480                 if ( !$conn ) {
 481                         throw new MWException( "Unable to connect to redis server." );
 482                 }
 483                 try {
 484                         $that = $this;
 485                         return new MappedIterator(
 486                                 $conn->lRange( $this->getQueueKey( 'l-unclaimed' ), 0, -1 ),
 487                                 function( $uid ) use ( $that, $conn ) {
 488                                         return $that->getJobFromUidInternal( $uid, $conn );
 489                                 }
 490                         );
 491                 } catch ( RedisException $e ) {
 492                         $this->throwRedisException( $this->server, $conn, $e );
 493                 }
 494         }
 495
 496         /**
 497          * @see JobQueue::getAllQueuedJobs()
 498          * @return Iterator
 499          */
 500         public function getAllDelayedJobs() {
 501                 $conn = $this->getConnection();
 502                 if ( !$conn ) {
 503                         throw new MWException( "Unable to connect to redis server." );
 504                 }
 505                 try {
 506                         $that = $this;
 507                         return new MappedIterator( // delayed jobs
 508                                 $conn->zRange( $this->getQueueKey( 'z-delayed' ), 0, -1 ),
 509                                 function( $uid ) use ( $that, $conn ) {
 510                                         return $that->getJobFromUidInternal( $uid, $conn );
 511                                 }
 512                         );
 513                 } catch ( RedisException $e ) {
 514                         $this->throwRedisException( $this->server, $conn, $e );
 515                 }
 516         }
 517
 518         /**
 519          * This function should not be called outside JobQueueRedis
 520          *
 521          * @param $uid string
 522          * @param $conn RedisConnRef
 523          * @return Job
 524          * @throws MWException
 525          */
 526         public function getJobFromUidInternal( $uid, RedisConnRef $conn ) {
 527                 try {
 528                         $item = unserialize( $conn->hGet( $this->getQueueKey( 'h-data' ), $uid ) );
 529                         if ( !is_array( $item ) ) { // this shouldn't happen
 530                                 throw new MWException( "Could not find job with ID '$uid'." );
 531                         }
 532                         $title = Title::makeTitle( $item['namespace'], $item['title'] );
 533                         $job = Job::factory( $item['type'], $title, $item['params'] );
 534                         $job->metadata['sourceFields'] = $item;
 535                         return $job;
 536                 } catch ( RedisException $e ) {
 537                         $this->throwRedisException( $this->server, $conn, $e );
 538                 }
 539         }
 540
 541         /**
 542          * Release any ready delayed jobs into the queue
 543          *
 544          * @return integer Number of jobs released
 545          * @throws MWException
 546          */
 547         public function releaseReadyDelayedJobs() {
 548                 $count = 0;
 549
 550                 $conn = $this->getConnection();
 551                 try {
 552                         static $script =
 553 <<<LUA
 554                         -- Get the list of ready delayed jobs, sorted by readiness
 555                         local ids = redis.call('zRangeByScore',KEYS[1],0,ARGV[1])
 556                         -- Migrate the jobs from the "delayed" set to the "unclaimed" list
 557                         for k,id in ipairs(ids) do
 558                                 redis.call('lPush',KEYS[2],id)
 559                                 redis.call('zRem',KEYS[1],id)
 560                         end
 561                         return #ids
 562 LUA;
 563                         $count += (int)$this->redisEval( $conn, $script,
 564                                 array(
 565                                         $this->getQueueKey( 'z-delayed' ), // KEYS[1]
 566                                         $this->getQueueKey( 'l-unclaimed' ), // KEYS[2]
 567                                         time() // ARGV[1]; max "delay until" UNIX timestamp
 568                                 ),
 569                                 2 # first two arguments are keys
 570                         );
 571                 } catch ( RedisException $e ) {
 572                         $this->throwRedisException( $this->server, $conn, $e );
 573                 }
 574
 575                 return $count;
 576         }
 577
 578         /**
 579          * Recycle or destroy any jobs that have been claimed for too long
 580          *
 581          * @return integer Number of jobs recycled/deleted
 582          * @throws MWException
 583          */
 584         public function recycleAndDeleteStaleJobs() {
 585                 if ( $this->claimTTL <= 0 ) { // sanity
 586                         throw new MWException( "Cannot recycle jobs since acknowledgements are disabled." );
 587                 }
 588                 $count = 0;
 589                 // For each job item that can be retried, we need to add it back to the
 590                 // main queue and remove it from the list of currenty claimed job items.
 591                 // For those that cannot, they are marked as dead and kept around for
 592                 // investigation and manual job restoration but are eventually deleted.
 593                 $conn = $this->getConnection();
 594                 try {
 595                         $now = time();
 596                         static $script =
 597 <<<LUA
 598                         local released,abandoned,pruned = 0,0,0
 599                         -- Get all non-dead jobs that have an expired claim on them.
 600                         -- The score for each item is the last claim timestamp (UNIX).
 601                         local staleClaims = redis.call('zRangeByScore',KEYS[1],0,ARGV[1],'WITHSCORES')
 602                         for id,timestamp in ipairs(staleClaims) do
 603                                 local attempts = redis.call('hGet',KEYS[2],id)
 604                                 if attempts < ARGV[3] then
 605                                         -- Claim expired and retries left: re-enqueue the job
 606                                         redis.call('lPush',KEYS[3],id)
 607                                         redis.call('hIncrBy',KEYS[2],id,1)
 608                                         released = released + 1
 609                                 else
 610                                         -- Claim expired and no retries left: mark the job as dead
 611                                         redis.call('zAdd',KEYS[5],timestamp,id)
 612                                         abandoned = abandoned + 1
 613                                 end
 614                                 redis.call('zRem',KEYS[1],id)
 615                         end
 616                         -- Get all of the dead jobs that have been marked as dead for too long.
 617                         -- The score for each item is the last claim timestamp (UNIX).
 618                         local deadClaims = redis.call('zRangeByScore',KEYS[5],0,ARGV[2],'WITHSCORES')
 619                         for id,timestamp in ipairs(deadClaims) do
 620                                 -- Stale and out of retries: remove any traces of the job
 621                                 redis.call('zRem',KEYS[5],id)
 622                                 redis.call('hDel',KEYS[2],id)
 623                                 redis.call('hDel',KEYS[4],id)
 624                                 pruned = pruned + 1
 625                         end
 626                         return {released,abandoned,pruned}
 627 LUA;
 628                         $res = $this->redisEval( $conn, $script,
 629                                 array(
 630                                         $this->getQueueKey( 'z-claimed' ), # KEYS[1]
 631                                         $this->getQueueKey( 'h-attempts' ), # KEYS[2]
 632                                         $this->getQueueKey( 'l-unclaimed' ), # KEYS[3]
 633                                         $this->getQueueKey( 'h-data' ), # KEYS[4]
 634                                         $this->getQueueKey( 'z-abandoned' ), # KEYS[5]
 635                                         $now - $this->claimTTL, # ARGV[1]
 636                                         $now - self::MAX_AGE_PRUNE, # ARGV[2]
 637                                         $this->maxTries # ARGV[3]
 638                                 ),
 639                                 5 # number of first argument(s) that are keys
 640                         );
 641                         if ( $res ) {
 642                                 list( $released, $abandoned, $pruned ) = $res;
 643                                 $count += $released + $pruned;
 644                                 wfIncrStats( 'job-recycle', count( $released ) );
 645                         }
 646                 } catch ( RedisException $e ) {
 647                         $this->throwRedisException( $this->server, $conn, $e );
 648                 }
 649
 650                 return $count;
 651         }
 652
 653         /**
 654          * @return Array
 655          */
 656         protected function doGetPeriodicTasks() {
 657                 $tasks = array();
 658                 if ( $this->claimTTL > 0 ) {
 659                         $tasks['recycleAndDeleteStaleJobs'] = array(
 660                                 'callback' => array( $this, 'recycleAndDeleteStaleJobs' ),
 661                                 'period'   => ceil( $this->claimTTL / 2 )
 662                         );
 663                 }
 664                 if ( $this->checkDelay ) {
 665                         $tasks['releaseReadyDelayedJobs'] = array(
 666                                 'callback' => array( $this, 'releaseReadyDelayedJobs' ),
 667                                 'period'   => 300 // 5 minutes
 668                         );
 669                 }
 670                 return $tasks;
 671         }
 672
 673         /**
 674          * @param RedisConnRef $conn
 675          * @param string $script
 676          * @param array $params
 677          * @param integer $numKeys
 678          * @return mixed
 679          */
 680         protected function redisEval( RedisConnRef $conn, $script, array $params, $numKeys ) {
 681                 $sha1 = sha1( $script ); // 40 char hex
 682
 683                 // Try to run the server-side cached copy of the script
 684                 $conn->clearLastError();
 685                 $res = $conn->evalSha( $sha1, $params, $numKeys );
 686                 // If the script is not in cache, use eval() to retry and cache it
 687                 if ( $conn->getLastError() && $conn->script( 'exists', $sha1 ) === array( 0 ) ) {
 688                         $conn->clearLastError();
 689                         $res = $conn->eval( $script, $params, $numKeys );
 690                         wfDebugLog( 'JobQueueRedis', "Used eval() for Lua script $sha1." );
 691                 }
 692
 693                 if ( $conn->getLastError() ) { // script bug?
 694                         wfDebugLog( 'JobQueueRedis', "Lua script error: " . $conn->getLastError() );
 695                 }
 696
 697                 return $res;
 698         }
 699
 700         /**
 701          * @param $job Job
 702          * @return array
 703          */
 704         protected function getNewJobFields( Job $job ) {
 705                 return array(
 706                         // Fields that describe the nature of the job
 707                         'type'       => $job->getType(),
 708                         'namespace'  => $job->getTitle()->getNamespace(),
 709                         'title'      => $job->getTitle()->getDBkey(),
 710                         'params'     => $job->getParams(),
 711                         // Some jobs cannot run until a "release timestamp"
 712                         'rtimestamp' => $job->getReleaseTimestamp() ?: 0,
 713                         // Additional job metadata
 714                         'uuid'       => UIDGenerator::newRawUUIDv4( UIDGenerator::QUICK_RAND ),
 715                         'sha1'       => $job->ignoreDuplicates()
 716                                 ? wfBaseConvert( sha1( serialize( $job->getDeduplicationInfo() ) ), 16, 36, 31 )
 717                                 : '',
 718                         'timestamp'  => time() // UNIX timestamp
 719                 );
 720         }
 721
 722         /**
 723          * @param $fields array
 724          * @return Job|bool
 725          */
 726         protected function getJobFromFields( array $fields ) {
 727                 $title = Title::makeTitleSafe( $fields['namespace'], $fields['title'] );
 728                 if ( $title ) {
 729                         $job = Job::factory( $fields['type'], $title, $fields['params'] );
 730                         $job->metadata['sourceFields'] = $fields;
 731                         return $job;
 732                 }
 733                 return false;
 734         }
 735
 736         /**
 737          * Get a connection to the server that handles all sub-queues for this queue
 738          *
 739          * @return Array (server name, Redis instance)
 740          * @throws MWException
 741          */
 742         protected function getConnection() {
 743                 $conn = $this->redisPool->getConnection( $this->server );
 744                 if ( !$conn ) {
 745                         throw new MWException( "Unable to connect to redis server." );
 746                 }
 747                 return $conn;
 748         }
 749
 750         /**
 751          * @param $server string
 752          * @param $conn RedisConnRef
 753          * @param $e RedisException
 754          * @throws MWException
 755          */
 756         protected function throwRedisException( $server, RedisConnRef $conn, $e ) {
 757                 $this->redisPool->handleException( $server, $conn, $e );
 758                 throw new MWException( "Redis server error: {$e->getMessage()}\n" );
 759         }
 760
 761         /**
 762          * @param $prop string
 763          * @return string
 764          */
 765         private function getQueueKey( $prop ) {
 766                 list( $db, $prefix ) = wfSplitWikiID( $this->wiki );
 767                 if ( strlen( $this->key ) ) { // namespaced queue (for testing)
 768                         return wfForeignMemcKey( $db, $prefix, 'jobqueue', $this->type, $this->key, $prop );
 769                 } else {
 770                         return wfForeignMemcKey( $db, $prefix, 'jobqueue', $this->type, $prop );
 771                 }
 772         }
 773
 774         /**
 775          * @param $key string
 776          * @return void
 777          */
 778         public function setTestingPrefix( $key ) {
 779                 $this->key = $key;
 780         }
 781 }