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 a faster and less resource-intensive job queue than 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 persistence. 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
  68         const MAX_AGE_PRUNE = 604800; // integer; seconds a job can live once claimed (7 days)
  69
  70         /** @var string Key to prefix the queue keys with (used for testing) */
  71         protected $key;
  72
  73         /**
  74          * @param array $params Possible keys:
  75          *   - redisConfig : An array of parameters to RedisConnectionPool::__construct().
  76          *                   Note that the serializer option is ignored as "none" is always used.
  77          *   - redisServer : A hostname/port combination or the absolute path of a UNIX socket.
  78          *                   If a hostname is specified but no port, the standard port number
  79          *                   6379 will be used. Required.
  80          *   - compression : The type of compression to use; one of (none,gzip).
  81          *   - daemonized  : Set to true if the redisJobRunnerService runs in the background.
  82          *                   This will disable job recycling/undelaying from the MediaWiki side
  83          *                   to avoid redundance and out-of-sync configuration.
  84          * @throws InvalidArgumentException
  85          */
  86         public function __construct( array $params ) {
  87                 parent::__construct( $params );
  88                 $params['redisConfig']['serializer'] = 'none'; // make it easy to use Lua
  89                 $this->server = $params['redisServer'];
  90                 $this->compression = isset( $params['compression'] ) ? $params['compression'] : 'none';
  91                 $this->redisPool = RedisConnectionPool::singleton( $params['redisConfig'] );
  92                 if ( empty( $params['daemonized'] ) ) {
  93                         throw new InvalidArgumentException(
  94                                 "Non-daemonized mode is no longer supported. Please install the " .
  95                                 "mediawiki/services/jobrunner service and update \$wgJobTypeConf as needed." );
  96                 }
  97         }
  98
  99         protected function supportedOrders() {
 100                 return array( 'timestamp', 'fifo' );
 101         }
 102
 103         protected function optimalOrder() {
 104                 return 'fifo';
 105         }
 106
 107         protected function supportsDelayedJobs() {
 108                 return true;
 109         }
 110
 111         /**
 112          * @see JobQueue::doIsEmpty()
 113          * @return bool
 114          * @throws JobQueueError
 115          */
 116         protected function doIsEmpty() {
 117                 return $this->doGetSize() == 0;
 118         }
 119
 120         /**
 121          * @see JobQueue::doGetSize()
 122          * @return int
 123          * @throws JobQueueError
 124          */
 125         protected function doGetSize() {
 126                 $conn = $this->getConnection();
 127                 try {
 128                         return $conn->lSize( $this->getQueueKey( 'l-unclaimed' ) );
 129                 } catch ( RedisException $e ) {
 130                         $this->throwRedisException( $conn, $e );
 131                 }
 132         }
 133
 134         /**
 135          * @see JobQueue::doGetAcquiredCount()
 136          * @return int
 137          * @throws JobQueueError
 138          */
 139         protected function doGetAcquiredCount() {
 140                 $conn = $this->getConnection();
 141                 try {
 142                         $conn->multi( Redis::PIPELINE );
 143                         $conn->zSize( $this->getQueueKey( 'z-claimed' ) );
 144                         $conn->zSize( $this->getQueueKey( 'z-abandoned' ) );
 145
 146                         return array_sum( $conn->exec() );
 147                 } catch ( RedisException $e ) {
 148                         $this->throwRedisException( $conn, $e );
 149                 }
 150         }
 151
 152         /**
 153          * @see JobQueue::doGetDelayedCount()
 154          * @return int
 155          * @throws JobQueueError
 156          */
 157         protected function doGetDelayedCount() {
 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, 100 ); // 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( 'inserts', $this->type, count( $items ) );
 227                         JobQueue::incrStats( 'dupe_inserts', $this->type,
 228                                 count( $items ) - $failed - $pushed );
 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                 $conn = $this->getConnection();
 297                 try {
 298                         do {
 299                                 $blob = $this->popAndAcquireBlob( $conn );
 300                                 if ( !is_string( $blob ) ) {
 301                                         break; // no jobs; nothing to do
 302                                 }
 303
 304                                 JobQueue::incrStats( 'job-pop', $this->type );
 305                                 $item = $this->unserialize( $blob );
 306                                 if ( $item === false ) {
 307                                         wfDebugLog( 'JobQueueRedis', "Could not unserialize {$this->type} job." );
 308                                         continue;
 309                                 }
 310
 311                                 // If $item is invalid, the runner loop recyling will cleanup as needed
 312                                 $job = $this->getJobFromFields( $item ); // may be false
 313                         } while ( !$job ); // job may be false if invalid
 314                 } catch ( RedisException $e ) {
 315                         $this->throwRedisException( $conn, $e );
 316                 }
 317
 318                 return $job;
 319         }
 320
 321         /**
 322          * @param RedisConnRef $conn
 323          * @return array Serialized string or false
 324          * @throws RedisException
 325          */
 326         protected function popAndAcquireBlob( RedisConnRef $conn ) {
 327                 static $script =
 328 <<<LUA
 329                 local kUnclaimed, kSha1ById, kIdBySha1, kClaimed, kAttempts, kData = unpack(KEYS)
 330                 -- Pop an item off the queue
 331                 local id = redis.call('rPop',kUnclaimed)
 332                 if not id then return false end
 333                 -- Allow new duplicates of this job
 334                 local sha1 = redis.call('hGet',kSha1ById,id)
 335                 if sha1 then redis.call('hDel',kIdBySha1,sha1) end
 336                 redis.call('hDel',kSha1ById,id)
 337                 -- Mark the jobs as claimed and return it
 338                 redis.call('zAdd',kClaimed,ARGV[1],id)
 339                 redis.call('hIncrBy',kAttempts,id,1)
 340                 return redis.call('hGet',kData,id)
 341 LUA;
 342                 return $conn->luaEval( $script,
 343                         array(
 344                                 $this->getQueueKey( 'l-unclaimed' ), # KEYS[1]
 345                                 $this->getQueueKey( 'h-sha1ById' ), # KEYS[2]
 346                                 $this->getQueueKey( 'h-idBySha1' ), # KEYS[3]
 347                                 $this->getQueueKey( 'z-claimed' ), # KEYS[4]
 348                                 $this->getQueueKey( 'h-attempts' ), # KEYS[5]
 349                                 $this->getQueueKey( 'h-data' ), # KEYS[6]
 350                                 time(), # ARGV[1] (injected to be replication-safe)
 351                         ),
 352                         6 # number of first argument(s) that are keys
 353                 );
 354         }
 355
 356         /**
 357          * @see JobQueue::doAck()
 358          * @param Job $job
 359          * @return Job|bool
 360          * @throws UnexpectedValueException
 361          * @throws JobQueueError
 362          */
 363         protected function doAck( Job $job ) {
 364                 if ( !isset( $job->metadata['uuid'] ) ) {
 365                         throw new UnexpectedValueException( "Job of type '{$job->getType()}' has no UUID." );
 366                 }
 367
 368                 $uuid = $job->metadata['uuid'];
 369                 $conn = $this->getConnection();
 370                 try {
 371                         static $script =
 372 <<<LUA
 373                         local kClaimed, kAttempts, kData = unpack(KEYS)
 374                         -- Unmark the job as claimed
 375                         redis.call('zRem',kClaimed,ARGV[1])
 376                         redis.call('hDel',kAttempts,ARGV[1])
 377                         -- Delete the job data itself
 378                         return redis.call('hDel',kData,ARGV[1])
 379 LUA;
 380                         $res = $conn->luaEval( $script,
 381                                 array(
 382                                         $this->getQueueKey( 'z-claimed' ), # KEYS[1]
 383                                         $this->getQueueKey( 'h-attempts' ), # KEYS[2]
 384                                         $this->getQueueKey( 'h-data' ), # KEYS[3]
 385                                         $uuid # ARGV[1]
 386                                 ),
 387                                 3 # number of first argument(s) that are keys
 388                         );
 389
 390                         if ( !$res ) {
 391                                 wfDebugLog( 'JobQueueRedis', "Could not acknowledge {$this->type} job $uuid." );
 392
 393                                 return false;
 394                         }
 395
 396                         JobQueue::incrStats( 'job-ack', $this->type );
 397                 } catch ( RedisException $e ) {
 398                         $this->throwRedisException( $conn, $e );
 399                 }
 400
 401                 return true;
 402         }
 403
 404         /**
 405          * @see JobQueue::doDeduplicateRootJob()
 406          * @param IJobSpecification $job
 407          * @return bool
 408          * @throws JobQueueError
 409          * @throws LogicException
 410          */
 411         protected function doDeduplicateRootJob( IJobSpecification $job ) {
 412                 if ( !$job->hasRootJobParams() ) {
 413                         throw new LogicException( "Cannot register root job; missing parameters." );
 414                 }
 415                 $params = $job->getRootJobParams();
 416
 417                 $key = $this->getRootJobCacheKey( $params['rootJobSignature'] );
 418
 419                 $conn = $this->getConnection();
 420                 try {
 421                         $timestamp = $conn->get( $key ); // current last timestamp of this job
 422                         if ( $timestamp && $timestamp >= $params['rootJobTimestamp'] ) {
 423                                 return true; // a newer version of this root job was enqueued
 424                         }
 425
 426                         // Update the timestamp of the last root job started at the location...
 427                         return $conn->set( $key, $params['rootJobTimestamp'], self::ROOTJOB_TTL ); // 2 weeks
 428                 } catch ( RedisException $e ) {
 429                         $this->throwRedisException( $conn, $e );
 430                 }
 431         }
 432
 433         /**
 434          * @see JobQueue::doIsRootJobOldDuplicate()
 435          * @param Job $job
 436          * @return bool
 437          * @throws JobQueueError
 438          */
 439         protected function doIsRootJobOldDuplicate( Job $job ) {
 440                 if ( !$job->hasRootJobParams() ) {
 441                         return false; // job has no de-deplication info
 442                 }
 443                 $params = $job->getRootJobParams();
 444
 445                 $conn = $this->getConnection();
 446                 try {
 447                         // Get the last time this root job was enqueued
 448                         $timestamp = $conn->get( $this->getRootJobCacheKey( $params['rootJobSignature'] ) );
 449                 } catch ( RedisException $e ) {
 450                         $timestamp = false;
 451                         $this->throwRedisException( $conn, $e );
 452                 }
 453
 454                 // Check if a new root job was started at the location after this one's...
 455                 return ( $timestamp && $timestamp > $params['rootJobTimestamp'] );
 456         }
 457
 458         /**
 459          * @see JobQueue::doDelete()
 460          * @return bool
 461          * @throws JobQueueError
 462          */
 463         protected function doDelete() {
 464                 static $props = array( 'l-unclaimed', 'z-claimed', 'z-abandoned',
 465                         'z-delayed', 'h-idBySha1', 'h-sha1ById', 'h-attempts', 'h-data' );
 466
 467                 $conn = $this->getConnection();
 468                 try {
 469                         $keys = array();
 470                         foreach ( $props as $prop ) {
 471                                 $keys[] = $this->getQueueKey( $prop );
 472                         }
 473
 474                         return ( $conn->delete( $keys ) !== false );
 475                 } catch ( RedisException $e ) {
 476                         $this->throwRedisException( $conn, $e );
 477                 }
 478         }
 479
 480         /**
 481          * @see JobQueue::getAllQueuedJobs()
 482          * @return Iterator
 483          * @throws JobQueueError
 484          */
 485         public function getAllQueuedJobs() {
 486                 $conn = $this->getConnection();
 487                 try {
 488                         $uids = $conn->lRange( $this->getQueueKey( 'l-unclaimed' ), 0, -1 );
 489                 } catch ( RedisException $e ) {
 490                         $this->throwRedisException( $conn, $e );
 491                 }
 492
 493                 return $this->getJobIterator( $conn, $uids );
 494         }
 495
 496         /**
 497          * @see JobQueue::getAllDelayedJobs()
 498          * @return Iterator
 499          * @throws JobQueueError
 500          */
 501         public function getAllDelayedJobs() {
 502                 $conn = $this->getConnection();
 503                 try {
 504                         $uids = $conn->zRange( $this->getQueueKey( 'z-delayed' ), 0, -1 );
 505                 } catch ( RedisException $e ) {
 506                         $this->throwRedisException( $conn, $e );
 507                 }
 508
 509                 return $this->getJobIterator( $conn, $uids );
 510         }
 511
 512         /**
 513          * @see JobQueue::getAllAcquiredJobs()
 514          * @return Iterator
 515          * @throws JobQueueError
 516          */
 517         public function getAllAcquiredJobs() {
 518                 $conn = $this->getConnection();
 519                 try {
 520                         $uids = $conn->zRange( $this->getQueueKey( 'z-claimed' ), 0, -1 );
 521                 } catch ( RedisException $e ) {
 522                         $this->throwRedisException( $conn, $e );
 523                 }
 524
 525                 return $this->getJobIterator( $conn, $uids );
 526         }
 527
 528         /**
 529          * @see JobQueue::getAllAbandonedJobs()
 530          * @return Iterator
 531          * @throws JobQueueError
 532          */
 533         public function getAllAbandonedJobs() {
 534                 $conn = $this->getConnection();
 535                 try {
 536                         $uids = $conn->zRange( $this->getQueueKey( 'z-abandoned' ), 0, -1 );
 537                 } catch ( RedisException $e ) {
 538                         $this->throwRedisException( $conn, $e );
 539                 }
 540
 541                 return $this->getJobIterator( $conn, $uids );
 542         }
 543
 544         /**
 545          * @param RedisConnRef $conn
 546          * @param array $uids List of job UUIDs
 547          * @return MappedIterator
 548          */
 549         protected function getJobIterator( RedisConnRef $conn, array $uids ) {
 550                 $that = $this;
 551
 552                 return new MappedIterator(
 553                         $uids,
 554                         function ( $uid ) use ( $that, $conn ) {
 555                                 return $that->getJobFromUidInternal( $uid, $conn );
 556                         },
 557                         array( 'accept' => function ( $job ) {
 558                                 return is_object( $job );
 559                         } )
 560                 );
 561         }
 562
 563         public function getCoalesceLocationInternal() {
 564                 return "RedisServer:" . $this->server;
 565         }
 566
 567         protected function doGetSiblingQueuesWithJobs( array $types ) {
 568                 return array_keys( array_filter( $this->doGetSiblingQueueSizes( $types ) ) );
 569         }
 570
 571         protected function doGetSiblingQueueSizes( array $types ) {
 572                 $sizes = array(); // (type => size)
 573                 $types = array_values( $types ); // reindex
 574                 $conn = $this->getConnection();
 575                 try {
 576                         $conn->multi( Redis::PIPELINE );
 577                         foreach ( $types as $type ) {
 578                                 $conn->lSize( $this->getQueueKey( 'l-unclaimed', $type ) );
 579                         }
 580                         $res = $conn->exec();
 581                         if ( is_array( $res ) ) {
 582                                 foreach ( $res as $i => $size ) {
 583                                         $sizes[$types[$i]] = $size;
 584                                 }
 585                         }
 586                 } catch ( RedisException $e ) {
 587                         $this->throwRedisException( $conn, $e );
 588                 }
 589
 590                 return $sizes;
 591         }
 592
 593         /**
 594          * This function should not be called outside JobQueueRedis
 595          *
 596          * @param string $uid
 597          * @param RedisConnRef $conn
 598          * @return Job|bool Returns false if the job does not exist
 599          * @throws JobQueueError
 600          * @throws UnexpectedValueException
 601          */
 602         public function getJobFromUidInternal( $uid, RedisConnRef $conn ) {
 603                 try {
 604                         $data = $conn->hGet( $this->getQueueKey( 'h-data' ), $uid );
 605                         if ( $data === false ) {
 606                                 return false; // not found
 607                         }
 608                         $item = $this->unserialize( $data );
 609                         if ( !is_array( $item ) ) { // this shouldn't happen
 610                                 throw new UnexpectedValueException( "Could not find job with ID '$uid'." );
 611                         }
 612                         $title = Title::makeTitle( $item['namespace'], $item['title'] );
 613                         $job = Job::factory( $item['type'], $title, $item['params'] );
 614                         $job->metadata['uuid'] = $item['uuid'];
 615                         $job->metadata['timestamp'] = $item['timestamp'];
 616
 617                         return $job;
 618                 } catch ( RedisException $e ) {
 619                         $this->throwRedisException( $conn, $e );
 620                 }
 621         }
 622
 623         /**
 624          * @param IJobSpecification $job
 625          * @return array
 626          */
 627         protected function getNewJobFields( IJobSpecification $job ) {
 628                 return array(
 629                         // Fields that describe the nature of the job
 630                         'type' => $job->getType(),
 631                         'namespace' => $job->getTitle()->getNamespace(),
 632                         'title' => $job->getTitle()->getDBkey(),
 633                         'params' => $job->getParams(),
 634                         // Some jobs cannot run until a "release timestamp"
 635                         'rtimestamp' => $job->getReleaseTimestamp() ?: 0,
 636                         // Additional job metadata
 637                         'uuid' => UIDGenerator::newRawUUIDv4( UIDGenerator::QUICK_RAND ),
 638                         'sha1' => $job->ignoreDuplicates()
 639                                 ? wfBaseConvert( sha1( serialize( $job->getDeduplicationInfo() ) ), 16, 36, 31 )
 640                                 : '',
 641                         'timestamp' => time() // UNIX timestamp
 642                 );
 643         }
 644
 645         /**
 646          * @param array $fields
 647          * @return Job|bool
 648          */
 649         protected function getJobFromFields( array $fields ) {
 650                 $title = Title::makeTitle( $fields['namespace'], $fields['title'] );
 651                 $job = Job::factory( $fields['type'], $title, $fields['params'] );
 652                 $job->metadata['uuid'] = $fields['uuid'];
 653                 $job->metadata['timestamp'] = $fields['timestamp'];
 654
 655                 return $job;
 656         }
 657
 658         /**
 659          * @param array $fields
 660          * @return string Serialized and possibly compressed version of $fields
 661          */
 662         protected function serialize( array $fields ) {
 663                 $blob = serialize( $fields );
 664                 if ( $this->compression === 'gzip'
 665                         && strlen( $blob ) >= 1024
 666                         && function_exists( 'gzdeflate' )
 667                 ) {
 668                         $object = (object)array( 'blob' => gzdeflate( $blob ), 'enc' => 'gzip' );
 669                         $blobz = serialize( $object );
 670
 671                         return ( strlen( $blobz ) < strlen( $blob ) ) ? $blobz : $blob;
 672                 } else {
 673                         return $blob;
 674                 }
 675         }
 676
 677         /**
 678          * @param string $blob
 679          * @return array|bool Unserialized version of $blob or false
 680          */
 681         protected function unserialize( $blob ) {
 682                 $fields = unserialize( $blob );
 683                 if ( is_object( $fields ) ) {
 684                         if ( $fields->enc === 'gzip' && function_exists( 'gzinflate' ) ) {
 685                                 $fields = unserialize( gzinflate( $fields->blob ) );
 686                         } else {
 687                                 $fields = false;
 688                         }
 689                 }
 690
 691                 return is_array( $fields ) ? $fields : false;
 692         }
 693
 694         /**
 695          * Get a connection to the server that handles all sub-queues for this queue
 696          *
 697          * @return RedisConnRef
 698          * @throws JobQueueConnectionError
 699          */
 700         protected function getConnection() {
 701                 $conn = $this->redisPool->getConnection( $this->server );
 702                 if ( !$conn ) {
 703                         throw new JobQueueConnectionError( "Unable to connect to redis server." );
 704                 }
 705
 706                 return $conn;
 707         }
 708
 709         /**
 710          * @param RedisConnRef $conn
 711          * @param RedisException $e
 712          * @throws JobQueueError
 713          */
 714         protected function throwRedisException( RedisConnRef $conn, $e ) {
 715                 $this->redisPool->handleError( $conn, $e );
 716                 throw new JobQueueError( "Redis server error: {$e->getMessage()}\n" );
 717         }
 718
 719         /**
 720          * @param string $prop
 721          * @param string|null $type
 722          * @return string
 723          */
 724         private function getQueueKey( $prop, $type = null ) {
 725                 $type = is_string( $type ) ? $type : $this->type;
 726                 list( $db, $prefix ) = wfSplitWikiID( $this->wiki );
 727                 if ( strlen( $this->key ) ) { // namespaced queue (for testing)
 728                         return wfForeignMemcKey( $db, $prefix, 'jobqueue', $type, $this->key, $prop );
 729                 } else {
 730                         return wfForeignMemcKey( $db, $prefix, 'jobqueue', $type, $prop );
 731                 }
 732         }
 733
 734         /**
 735          * @param string $key
 736          * @return void
 737          */
 738         public function setTestingPrefix( $key ) {
 739                 $this->key = $key;
 740         }
 741 }