includes/jobqueue/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         /** @var string Server address */
  64         protected $server;
  65         /** @var string Compression method to use */
  66         protected $compression;
  67         /** @var bool */
  68         protected $daemonized;
  69
  70         const MAX_AGE_PRUNE = 604800; // integer; seconds a job can live once claimed (7 days)
  71
  72         /** @var string Key to prefix the queue keys with (used for testing) */
  73         protected $key;
  74
  75         /**
  76          * @param array $params Possible keys:
  77          *   - redisConfig : An array of parameters to RedisConnectionPool::__construct().
  78          *                   Note that the serializer option is ignored as "none" is always used.
  79          *   - redisServer : A hostname/port combination or the absolute path of a UNIX socket.
  80          *                   If a hostname is specified but no port, the standard port number
  81          *                   6379 will be used. Required.
  82          *   - compression : The type of compression to use; one of (none,gzip).
  83          *   - daemonized  : Set to true if the redisJobRunnerService runs in the background.
  84          *                   This will disable job recycling/undelaying from the MediaWiki side
  85          *                   to avoid redundance and out-of-sync configuration.
  86          */
  87         public function __construct( array $params ) {
  88                 parent::__construct( $params );
  89                 $params['redisConfig']['serializer'] = 'none'; // make it easy to use Lua
  90                 $this->server = $params['redisServer'];
  91                 $this->compression = isset( $params['compression'] ) ? $params['compression'] : 'none';
  92                 $this->redisPool = RedisConnectionPool::singleton( $params['redisConfig'] );
  93                 $this->daemonized = !empty( $params['daemonized'] );
  94         }
  95
  96         protected function supportedOrders() {
  97                 return array( 'timestamp', 'fifo' );
  98         }
  99
 100         protected function optimalOrder() {
 101                 return 'fifo';
 102         }
 103
 104         protected function supportsDelayedJobs() {
 105                 return true;
 106         }
 107
 108         /**
 109          * @see JobQueue::doIsEmpty()
 110          * @return bool
 111          * @throws MWException
 112          */
 113         protected function doIsEmpty() {
 114                 return $this->doGetSize() == 0;
 115         }
 116
 117         /**
 118          * @see JobQueue::doGetSize()
 119          * @return int
 120          * @throws MWException
 121          */
 122         protected function doGetSize() {
 123                 $conn = $this->getConnection();
 124                 try {
 125                         return $conn->lSize( $this->getQueueKey( 'l-unclaimed' ) );
 126                 } catch ( RedisException $e ) {
 127                         $this->throwRedisException( $conn, $e );
 128                 }
 129         }
 130
 131         /**
 132          * @see JobQueue::doGetAcquiredCount()
 133          * @return int
 134          * @throws JobQueueError
 135          */
 136         protected function doGetAcquiredCount() {
 137                 $conn = $this->getConnection();
 138                 try {
 139                         $conn->multi( Redis::PIPELINE );
 140                         $conn->zSize( $this->getQueueKey( 'z-claimed' ) );
 141                         $conn->zSize( $this->getQueueKey( 'z-abandoned' ) );
 142
 143                         return array_sum( $conn->exec() );
 144                 } catch ( RedisException $e ) {
 145                         $this->throwRedisException( $conn, $e );
 146                 }
 147         }
 148
 149         /**
 150          * @see JobQueue::doGetDelayedCount()
 151          * @return int
 152          * @throws JobQueueError
 153          */
 154         protected function doGetDelayedCount() {
 155                 if ( !$this->checkDelay ) {
 156                         return 0; // no delayed jobs
 157                 }
 158                 $conn = $this->getConnection();
 159                 try {
 160                         return $conn->zSize( $this->getQueueKey( 'z-delayed' ) );
 161                 } catch ( RedisException $e ) {
 162                         $this->throwRedisException( $conn, $e );
 163                 }
 164         }
 165
 166         /**
 167          * @see JobQueue::doGetAbandonedCount()
 168          * @return int
 169          * @throws JobQueueError
 170          */
 171         protected function doGetAbandonedCount() {
 172                 $conn = $this->getConnection();
 173                 try {
 174                         return $conn->zSize( $this->getQueueKey( 'z-abandoned' ) );
 175                 } catch ( RedisException $e ) {
 176                         $this->throwRedisException( $conn, $e );
 177                 }
 178         }
 179
 180         /**
 181          * @see JobQueue::doBatchPush()
 182          * @param array $jobs
 183          * @param int $flags
 184          * @return void
 185          * @throws JobQueueError
 186          */
 187         protected function doBatchPush( array $jobs, $flags ) {
 188                 // Convert the jobs into field maps (de-duplicated against each other)
 189                 $items = array(); // (job ID => job fields map)
 190                 foreach ( $jobs as $job ) {
 191                         $item = $this->getNewJobFields( $job );
 192                         if ( strlen( $item['sha1'] ) ) { // hash identifier => de-duplicate
 193                                 $items[$item['sha1']] = $item;
 194                         } else {
 195                                 $items[$item['uuid']] = $item;
 196                         }
 197                 }
 198
 199                 if ( !count( $items ) ) {
 200                         return; // nothing to do
 201                 }
 202
 203                 $conn = $this->getConnection();
 204                 try {
 205                         // Actually push the non-duplicate jobs into the queue...
 206                         if ( $flags & self::QOS_ATOMIC ) {
 207                                 $batches = array( $items ); // all or nothing
 208                         } else {
 209                                 $batches = array_chunk( $items, 500 ); // avoid tying up the server
 210                         }
 211                         $failed = 0;
 212                         $pushed = 0;
 213                         foreach ( $batches as $itemBatch ) {
 214                                 $added = $this->pushBlobs( $conn, $itemBatch );
 215                                 if ( is_int( $added ) ) {
 216                                         $pushed += $added;
 217                                 } else {
 218                                         $failed += count( $itemBatch );
 219                                 }
 220                         }
 221                         if ( $failed > 0 ) {
 222                                 wfDebugLog( 'JobQueueRedis', "Could not insert {$failed} {$this->type} job(s)." );
 223
 224                                 throw new RedisException( "Could not insert {$failed} {$this->type} job(s)." );
 225                         }
 226                         JobQueue::incrStats( 'job-insert', $this->type, count( $items ), $this->wiki );
 227                         JobQueue::incrStats( 'job-insert-duplicate', $this->type,
 228                                 count( $items ) - $failed - $pushed, $this->wiki );
 229                 } catch ( RedisException $e ) {
 230                         $this->throwRedisException( $conn, $e );
 231                 }
 232         }
 233
 234         /**
 235          * @param RedisConnRef $conn
 236          * @param array $items List of results from JobQueueRedis::getNewJobFields()
 237          * @return int Number of jobs inserted (duplicates are ignored)
 238          * @throws RedisException
 239          */
 240         protected function pushBlobs( RedisConnRef $conn, array $items ) {
 241                 $args = array(); // ([id, sha1, rtime, blob [, id, sha1, rtime, blob ... ] ] )
 242                 foreach ( $items as $item ) {
 243                         $args[] = (string)$item['uuid'];
 244                         $args[] = (string)$item['sha1'];
 245                         $args[] = (string)$item['rtimestamp'];
 246                         $args[] = (string)$this->serialize( $item );
 247                 }
 248                 static $script =
 249 <<<LUA
 250                 local kUnclaimed, kSha1ById, kIdBySha1, kDelayed, kData = unpack(KEYS)
 251                 if #ARGV % 4 ~= 0 then return redis.error_reply('Unmatched arguments') end
 252                 local pushed = 0
 253                 for i = 1,#ARGV,4 do
 254                         local id,sha1,rtimestamp,blob = ARGV[i],ARGV[i+1],ARGV[i+2],ARGV[i+3]
 255                         if sha1 == '' or redis.call('hExists',kIdBySha1,sha1) == 0 then
 256                                 if 1*rtimestamp > 0 then
 257                                         -- Insert into delayed queue (release time as score)
 258                                         redis.call('zAdd',kDelayed,rtimestamp,id)
 259                                 else
 260                                         -- Insert into unclaimed queue
 261                                         redis.call('lPush',kUnclaimed,id)
 262                                 end
 263                                 if sha1 ~= '' then
 264                                         redis.call('hSet',kSha1ById,id,sha1)
 265                                         redis.call('hSet',kIdBySha1,sha1,id)
 266                                 end
 267                                 redis.call('hSet',kData,id,blob)
 268                                 pushed = pushed + 1
 269                         end
 270                 end
 271                 return pushed
 272 LUA;
 273                 return $conn->luaEval( $script,
 274                         array_merge(
 275                                 array(
 276                                         $this->getQueueKey( 'l-unclaimed' ), # KEYS[1]
 277                                         $this->getQueueKey( 'h-sha1ById' ), # KEYS[2]
 278                                         $this->getQueueKey( 'h-idBySha1' ), # KEYS[3]
 279                                         $this->getQueueKey( 'z-delayed' ), # KEYS[4]
 280                                         $this->getQueueKey( 'h-data' ), # KEYS[5]
 281                                 ),
 282                                 $args
 283                         ),
 284                         5 # number of first argument(s) that are keys
 285                 );
 286         }
 287
 288         /**
 289          * @see JobQueue::doPop()
 290          * @return Job|bool
 291          * @throws JobQueueError
 292          */
 293         protected function doPop() {
 294                 $job = false;
 295
 296                 // Push ready delayed jobs into the queue every 10 jobs to spread the load.
 297                 // This is also done as a periodic task, but we don't want too much done at once.
 298                 if ( !$this->daemonized && $this->checkDelay && mt_rand( 0, 9 ) == 0 ) {
 299                         $this->recyclePruneAndUndelayJobs();
 300                 }
 301
 302                 $conn = $this->getConnection();
 303                 try {
 304                         do {
 305                                 // Keep the claimed job list down for high-traffic queues
 306                                 if ( !$this->daemonized && mt_rand( 0, 99 ) == 0 ) {
 307                                         $this->recyclePruneAndUndelayJobs();
 308                                 }
 309                                 $blob = $this->popAndAcquireBlob( $conn );
 310                                 if ( !is_string( $blob ) ) {
 311                                         break; // no jobs; nothing to do
 312                                 }
 313
 314                                 JobQueue::incrStats( 'job-pop', $this->type, 1, $this->wiki );
 315                                 $item = $this->unserialize( $blob );
 316                                 if ( $item === false ) {
 317                                         wfDebugLog( 'JobQueueRedis', "Could not unserialize {$this->type} job." );
 318                                         continue;
 319                                 }
 320
 321                                 // If $item is invalid, recyclePruneAndUndelayJobs() will cleanup as needed
 322                                 $job = $this->getJobFromFields( $item ); // may be false
 323                         } while ( !$job ); // job may be false if invalid
 324                 } catch ( RedisException $e ) {
 325                         $this->throwRedisException( $conn, $e );
 326                 }
 327
 328                 return $job;
 329         }
 330
 331         /**
 332          * @param RedisConnRef $conn
 333          * @return array Serialized string or false
 334          * @throws RedisException
 335          */
 336         protected function popAndAcquireBlob( RedisConnRef $conn ) {
 337                 static $script =
 338 <<<LUA
 339                 local kUnclaimed, kSha1ById, kIdBySha1, kClaimed, kAttempts, kData = unpack(KEYS)
 340                 -- Pop an item off the queue
 341                 local id = redis.call('rPop',kUnclaimed)
 342                 if not id then return false end
 343                 -- Allow new duplicates of this job
 344                 local sha1 = redis.call('hGet',kSha1ById,id)
 345                 if sha1 then redis.call('hDel',kIdBySha1,sha1) end
 346                 redis.call('hDel',kSha1ById,id)
 347                 -- Mark the jobs as claimed and return it
 348                 redis.call('zAdd',kClaimed,ARGV[1],id)
 349                 redis.call('hIncrBy',kAttempts,id,1)
 350                 return redis.call('hGet',kData,id)
 351 LUA;
 352                 return $conn->luaEval( $script,
 353                         array(
 354                                 $this->getQueueKey( 'l-unclaimed' ), # KEYS[1]
 355                                 $this->getQueueKey( 'h-sha1ById' ), # KEYS[2]
 356                                 $this->getQueueKey( 'h-idBySha1' ), # KEYS[3]
 357                                 $this->getQueueKey( 'z-claimed' ), # KEYS[4]
 358                                 $this->getQueueKey( 'h-attempts' ), # KEYS[5]
 359                                 $this->getQueueKey( 'h-data' ), # KEYS[6]
 360                                 time(), # ARGV[1] (injected to be replication-safe)
 361                         ),
 362                         6 # number of first argument(s) that are keys
 363                 );
 364         }
 365
 366         /**
 367          * @see JobQueue::doAck()
 368          * @param Job $job
 369          * @return Job|bool
 370          * @throws MWException|JobQueueError
 371          */
 372         protected function doAck( Job $job ) {
 373                 if ( !isset( $job->metadata['uuid'] ) ) {
 374                         throw new MWException( "Job of type '{$job->getType()}' has no UUID." );
 375                 }
 376
 377                 $conn = $this->getConnection();
 378                 try {
 379                         static $script =
 380 <<<LUA
 381                         local kClaimed, kAttempts, kData = unpack(KEYS)
 382                         -- Unmark the job as claimed
 383                         redis.call('zRem',kClaimed,ARGV[1])
 384                         redis.call('hDel',kAttempts,ARGV[1])
 385                         -- Delete the job data itself
 386                         return redis.call('hDel',kData,ARGV[1])
 387 LUA;
 388                         $res = $conn->luaEval( $script,
 389                                 array(
 390                                         $this->getQueueKey( 'z-claimed' ), # KEYS[1]
 391                                         $this->getQueueKey( 'h-attempts' ), # KEYS[2]
 392                                         $this->getQueueKey( 'h-data' ), # KEYS[3]
 393                                         $job->metadata['uuid'] # ARGV[1]
 394                                 ),
 395                                 3 # number of first argument(s) that are keys
 396                         );
 397
 398                         if ( !$res ) {
 399                                 wfDebugLog( 'JobQueueRedis', "Could not acknowledge {$this->type} job." );
 400
 401                                 return false;
 402                         }
 403                 } catch ( RedisException $e ) {
 404                         $this->throwRedisException( $conn, $e );
 405                 }
 406
 407                 return true;
 408         }
 409
 410         /**
 411          * @see JobQueue::doDeduplicateRootJob()
 412          * @param Job $job
 413          * @return bool
 414          * @throws MWException|JobQueueError
 415          */
 416         protected function doDeduplicateRootJob( Job $job ) {
 417                 if ( !$job->hasRootJobParams() ) {
 418                         throw new MWException( "Cannot register root job; missing parameters." );
 419                 }
 420                 $params = $job->getRootJobParams();
 421
 422                 $key = $this->getRootJobCacheKey( $params['rootJobSignature'] );
 423
 424                 $conn = $this->getConnection();
 425                 try {
 426                         $timestamp = $conn->get( $key ); // current last timestamp of this job
 427                         if ( $timestamp && $timestamp >= $params['rootJobTimestamp'] ) {
 428                                 return true; // a newer version of this root job was enqueued
 429                         }
 430
 431                         // Update the timestamp of the last root job started at the location...
 432                         return $conn->set( $key, $params['rootJobTimestamp'], self::ROOTJOB_TTL ); // 2 weeks
 433                 } catch ( RedisException $e ) {
 434                         $this->throwRedisException( $conn, $e );
 435                 }
 436         }
 437
 438         /**
 439          * @see JobQueue::doIsRootJobOldDuplicate()
 440          * @param Job $job
 441          * @return bool
 442          * @throws JobQueueError
 443          */
 444         protected function doIsRootJobOldDuplicate( Job $job ) {
 445                 if ( !$job->hasRootJobParams() ) {
 446                         return false; // job has no de-deplication info
 447                 }
 448                 $params = $job->getRootJobParams();
 449
 450                 $conn = $this->getConnection();
 451                 try {
 452                         // Get the last time this root job was enqueued
 453                         $timestamp = $conn->get( $this->getRootJobCacheKey( $params['rootJobSignature'] ) );
 454                 } catch ( RedisException $e ) {
 455                         $this->throwRedisException( $conn, $e );
 456                 }
 457
 458                 // Check if a new root job was started at the location after this one's...
 459                 return ( $timestamp && $timestamp > $params['rootJobTimestamp'] );
 460         }
 461
 462         /**
 463          * @see JobQueue::doDelete()
 464          * @return bool
 465          * @throws JobQueueError
 466          */
 467         protected function doDelete() {
 468                 static $props = array( 'l-unclaimed', 'z-claimed', 'z-abandoned',
 469                         'z-delayed', 'h-idBySha1', 'h-sha1ById', 'h-attempts', 'h-data' );
 470
 471                 $conn = $this->getConnection();
 472                 try {
 473                         $keys = array();
 474                         foreach ( $props as $prop ) {
 475                                 $keys[] = $this->getQueueKey( $prop );
 476                         }
 477
 478                         return ( $conn->delete( $keys ) !== false );
 479                 } catch ( RedisException $e ) {
 480                         $this->throwRedisException( $conn, $e );
 481                 }
 482         }
 483
 484         /**
 485          * @see JobQueue::getAllQueuedJobs()
 486          * @return Iterator
 487          */
 488         public function getAllQueuedJobs() {
 489                 $conn = $this->getConnection();
 490                 try {
 491                         $that = $this;
 492
 493                         return new MappedIterator(
 494                                 $conn->lRange( $this->getQueueKey( 'l-unclaimed' ), 0, -1 ),
 495                                 function ( $uid ) use ( $that, $conn ) {
 496                                         return $that->getJobFromUidInternal( $uid, $conn );
 497                                 },
 498                                 array( 'accept' => function ( $job ) {
 499                                         return is_object( $job );
 500                                 } )
 501                         );
 502                 } catch ( RedisException $e ) {
 503                         $this->throwRedisException( $conn, $e );
 504                 }
 505         }
 506
 507         /**
 508          * @see JobQueue::getAllQueuedJobs()
 509          * @return Iterator
 510          */
 511         public function getAllDelayedJobs() {
 512                 $conn = $this->getConnection();
 513                 try {
 514                         $that = $this;
 515
 516                         return new MappedIterator( // delayed jobs
 517                                 $conn->zRange( $this->getQueueKey( 'z-delayed' ), 0, -1 ),
 518                                 function ( $uid ) use ( $that, $conn ) {
 519                                         return $that->getJobFromUidInternal( $uid, $conn );
 520                                 },
 521                                 array( 'accept' => function ( $job ) {
 522                                         return is_object( $job );
 523                                 } )
 524                         );
 525                 } catch ( RedisException $e ) {
 526                         $this->throwRedisException( $conn, $e );
 527                 }
 528         }
 529
 530         public function getCoalesceLocationInternal() {
 531                 return "RedisServer:" . $this->server;
 532         }
 533
 534         protected function doGetSiblingQueuesWithJobs( array $types ) {
 535                 return array_keys( array_filter( $this->doGetSiblingQueueSizes( $types ) ) );
 536         }
 537
 538         protected function doGetSiblingQueueSizes( array $types ) {
 539                 $sizes = array(); // (type => size)
 540                 $types = array_values( $types ); // reindex
 541                 $conn = $this->getConnection();
 542                 try {
 543                         $conn->multi( Redis::PIPELINE );
 544                         foreach ( $types as $type ) {
 545                                 $conn->lSize( $this->getQueueKey( 'l-unclaimed', $type ) );
 546                         }
 547                         $res = $conn->exec();
 548                         if ( is_array( $res ) ) {
 549                                 foreach ( $res as $i => $size ) {
 550                                         $sizes[$types[$i]] = $size;
 551                                 }
 552                         }
 553                 } catch ( RedisException $e ) {
 554                         $this->throwRedisException( $conn, $e );
 555                 }
 556
 557                 return $sizes;
 558         }
 559
 560         /**
 561          * This function should not be called outside JobQueueRedis
 562          *
 563          * @param string $uid
 564          * @param RedisConnRef $conn
 565          * @return Job|bool Returns false if the job does not exist
 566          * @throws MWException|JobQueueError
 567          */
 568         public function getJobFromUidInternal( $uid, RedisConnRef $conn ) {
 569                 try {
 570                         $data = $conn->hGet( $this->getQueueKey( 'h-data' ), $uid );
 571                         if ( $data === false ) {
 572                                 return false; // not found
 573                         }
 574                         $item = $this->unserialize( $conn->hGet( $this->getQueueKey( 'h-data' ), $uid ) );
 575                         if ( !is_array( $item ) ) { // this shouldn't happen
 576                                 throw new MWException( "Could not find job with ID '$uid'." );
 577                         }
 578                         $title = Title::makeTitle( $item['namespace'], $item['title'] );
 579                         $job = Job::factory( $item['type'], $title, $item['params'] );
 580                         $job->metadata['uuid'] = $item['uuid'];
 581
 582                         return $job;
 583                 } catch ( RedisException $e ) {
 584                         $this->throwRedisException( $conn, $e );
 585                 }
 586         }
 587
 588         /**
 589          * Recycle or destroy any jobs that have been claimed for too long
 590          * and release any ready delayed jobs into the queue
 591          *
 592          * @return int Number of jobs recycled/deleted/undelayed
 593          * @throws MWException|JobQueueError
 594          */
 595         public function recyclePruneAndUndelayJobs() {
 596                 $count = 0;
 597                 // For each job item that can be retried, we need to add it back to the
 598                 // main queue and remove it from the list of currenty claimed job items.
 599                 // For those that cannot, they are marked as dead and kept around for
 600                 // investigation and manual job restoration but are eventually deleted.
 601                 $conn = $this->getConnection();
 602                 try {
 603                         $now = time();
 604                         static $script =
 605 <<<LUA
 606                         local kClaimed, kAttempts, kUnclaimed, kData, kAbandoned, kDelayed = unpack(KEYS)
 607                         local released,abandoned,pruned,undelayed = 0,0,0,0
 608                         -- Get all non-dead jobs that have an expired claim on them.
 609                         -- The score for each item is the last claim timestamp (UNIX).
 610                         local staleClaims = redis.call('zRangeByScore',kClaimed,0,ARGV[1])
 611                         for k,id in ipairs(staleClaims) do
 612                                 local timestamp = redis.call('zScore',kClaimed,id)
 613                                 local attempts = redis.call('hGet',kAttempts,id)
 614                                 if attempts < ARGV[3] then
 615                                         -- Claim expired and retries left: re-enqueue the job
 616                                         redis.call('lPush',kUnclaimed,id)
 617                                         released = released + 1
 618                                 else
 619                                         -- Claim expired and no retries left: mark the job as dead
 620                                         redis.call('zAdd',kAbandoned,timestamp,id)
 621                                         abandoned = abandoned + 1
 622                                 end
 623                                 redis.call('zRem',kClaimed,id)
 624                         end
 625                         -- Get all of the dead jobs that have been marked as dead for too long.
 626                         -- The score for each item is the last claim timestamp (UNIX).
 627                         local deadClaims = redis.call('zRangeByScore',kAbandoned,0,ARGV[2])
 628                         for k,id in ipairs(deadClaims) do
 629                                 -- Stale and out of retries: remove any traces of the job
 630                                 redis.call('zRem',kAbandoned,id)
 631                                 redis.call('hDel',kAttempts,id)
 632                                 redis.call('hDel',kData,id)
 633                                 pruned = pruned + 1
 634                         end
 635                         -- Get the list of ready delayed jobs, sorted by readiness (UNIX timestamp)
 636                         local ids = redis.call('zRangeByScore',kDelayed,0,ARGV[4])
 637                         -- Migrate the jobs from the "delayed" set to the "unclaimed" list
 638                         for k,id in ipairs(ids) do
 639                                 redis.call('lPush',kUnclaimed,id)
 640                                 redis.call('zRem',kDelayed,id)
 641                         end
 642                         undelayed = #ids
 643                         return {released,abandoned,pruned,undelayed}
 644 LUA;
 645                         $res = $conn->luaEval( $script,
 646                                 array(
 647                                         $this->getQueueKey( 'z-claimed' ), # KEYS[1]
 648                                         $this->getQueueKey( 'h-attempts' ), # KEYS[2]
 649                                         $this->getQueueKey( 'l-unclaimed' ), # KEYS[3]
 650                                         $this->getQueueKey( 'h-data' ), # KEYS[4]
 651                                         $this->getQueueKey( 'z-abandoned' ), # KEYS[5]
 652                                         $this->getQueueKey( 'z-delayed' ), # KEYS[6]
 653                                         $now - $this->claimTTL, # ARGV[1]
 654                                         $now - self::MAX_AGE_PRUNE, # ARGV[2]
 655                                         $this->maxTries, # ARGV[3]
 656                                         $now # ARGV[4]
 657                                 ),
 658                                 6 # number of first argument(s) that are keys
 659                         );
 660                         if ( $res ) {
 661                                 list( $released, $abandoned, $pruned, $undelayed ) = $res;
 662                                 $count += $released + $pruned + $undelayed;
 663                                 JobQueue::incrStats( 'job-recycle', $this->type, $released, $this->wiki );
 664                                 JobQueue::incrStats( 'job-abandon', $this->type, $abandoned, $this->wiki );
 665                                 JobQueue::incrStats( 'job-undelay', $this->type, $undelayed, $this->wiki );
 666                         }
 667                 } catch ( RedisException $e ) {
 668                         $this->throwRedisException( $conn, $e );
 669                 }
 670
 671                 return $count;
 672         }
 673
 674         /**
 675          * @return array
 676          */
 677         protected function doGetPeriodicTasks() {
 678                 if ( $this->daemonized ) {
 679                         return array(); // managed in the runner loop
 680                 }
 681                 $periods = array( 3600 ); // standard cleanup (useful on config change)
 682                 if ( $this->claimTTL > 0 ) {
 683                         $periods[] = ceil( $this->claimTTL / 2 ); // halved to avoid bad timing
 684                 }
 685                 if ( $this->checkDelay ) {
 686                         $periods[] = 300; // 5 minutes
 687                 }
 688                 $period = min( $periods );
 689                 $period = max( $period, 30 ); // sanity
 690
 691                 return array(
 692                         'recyclePruneAndUndelayJobs' => array(
 693                                 'callback' => array( $this, 'recyclePruneAndUndelayJobs' ),
 694                                 'period'   => $period,
 695                         )
 696                 );
 697         }
 698
 699         /**
 700          * @param IJobSpecification $job
 701          * @return array
 702          */
 703         protected function getNewJobFields( IJobSpecification $job ) {
 704                 return array(
 705                         // Fields that describe the nature of the job
 706                         'type' => $job->getType(),
 707                         'namespace' => $job->getTitle()->getNamespace(),
 708                         'title' => $job->getTitle()->getDBkey(),
 709                         'params' => $job->getParams(),
 710                         // Some jobs cannot run until a "release timestamp"
 711                         'rtimestamp' => $job->getReleaseTimestamp() ?: 0,
 712                         // Additional job metadata
 713                         'uuid' => UIDGenerator::newRawUUIDv4( UIDGenerator::QUICK_RAND ),
 714                         'sha1' => $job->ignoreDuplicates()
 715                                 ? wfBaseConvert( sha1( serialize( $job->getDeduplicationInfo() ) ), 16, 36, 31 )
 716                                 : '',
 717                         'timestamp' => time() // UNIX timestamp
 718                 );
 719         }
 720
 721         /**
 722          * @param array $fields
 723          * @return Job|bool
 724          */
 725         protected function getJobFromFields( array $fields ) {
 726                 $title = Title::makeTitleSafe( $fields['namespace'], $fields['title'] );
 727                 if ( $title ) {
 728                         $job = Job::factory( $fields['type'], $title, $fields['params'] );
 729                         $job->metadata['uuid'] = $fields['uuid'];
 730
 731                         return $job;
 732                 }
 733
 734                 return false;
 735         }
 736
 737         /**
 738          * @param array $fields
 739          * @return string Serialized and possibly compressed version of $fields
 740          */
 741         protected function serialize( array $fields ) {
 742                 $blob = serialize( $fields );
 743                 if ( $this->compression === 'gzip'
 744                         && strlen( $blob ) >= 1024
 745                         && function_exists( 'gzdeflate' )
 746                 ) {
 747                         $object = (object)array( 'blob' => gzdeflate( $blob ), 'enc' => 'gzip' );
 748                         $blobz = serialize( $object );
 749
 750                         return ( strlen( $blobz ) < strlen( $blob ) ) ? $blobz : $blob;
 751                 } else {
 752                         return $blob;
 753                 }
 754         }
 755
 756         /**
 757          * @param string $blob
 758          * @return array|bool Unserialized version of $blob or false
 759          */
 760         protected function unserialize( $blob ) {
 761                 $fields = unserialize( $blob );
 762                 if ( is_object( $fields ) ) {
 763                         if ( $fields->enc === 'gzip' && function_exists( 'gzinflate' ) ) {
 764                                 $fields = unserialize( gzinflate( $fields->blob ) );
 765                         } else {
 766                                 $fields = false;
 767                         }
 768                 }
 769
 770                 return is_array( $fields ) ? $fields : false;
 771         }
 772
 773         /**
 774          * Get a connection to the server that handles all sub-queues for this queue
 775          *
 776          * @return RedisConnRef
 777          * @throws JobQueueConnectionError
 778          */
 779         protected function getConnection() {
 780                 $conn = $this->redisPool->getConnection( $this->server );
 781                 if ( !$conn ) {
 782                         throw new JobQueueConnectionError( "Unable to connect to redis server." );
 783                 }
 784
 785                 return $conn;
 786         }
 787
 788         /**
 789          * @param RedisConnRef $conn
 790          * @param RedisException $e
 791          * @throws JobQueueError
 792          */
 793         protected function throwRedisException( RedisConnRef $conn, $e ) {
 794                 $this->redisPool->handleError( $conn, $e );
 795                 throw new JobQueueError( "Redis server error: {$e->getMessage()}\n" );
 796         }
 797
 798         /**
 799          * @param string $prop
 800          * @param string|null $type
 801          * @return string
 802          */
 803         private function getQueueKey( $prop, $type = null ) {
 804                 $type = is_string( $type ) ? $type : $this->type;
 805                 list( $db, $prefix ) = wfSplitWikiID( $this->wiki );
 806                 if ( strlen( $this->key ) ) { // namespaced queue (for testing)
 807                         return wfForeignMemcKey( $db, $prefix, 'jobqueue', $type, $this->key, $prop );
 808                 } else {
 809                         return wfForeignMemcKey( $db, $prefix, 'jobqueue', $type, $prop );
 810                 }
 811         }
 812
 813         /**
 814          * @param string $key
 815          * @return void
 816          */
 817         public function setTestingPrefix( $key ) {
 818                 $this->key = $key;
 819         }
 820 }