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
  66         /** @var string Compression method to use */
  67         protected $compression;
  68
  69         const MAX_AGE_PRUNE = 604800; // integer; seconds a job can live once claimed (7 days)
  70
  71         /** @var string Key to prefix the queue keys with (used for testing) */
  72         protected $key;
  73
  74         /**
  75          * @params include:
  76          *   - redisConfig : An array of parameters to RedisConnectionPool::__construct().
  77          *                   Note that the serializer option is ignored as "none" is always used.
  78          *   - redisServer : A hostname/port combination or the absolute path of a UNIX socket.
  79          *                   If a hostname is specified but no port, the standard port number
  80          *                   6379 will be used. Required.
  81          *   - compression : The type of compression to use; one of (none,gzip).
  82          * @param array $params
  83          */
  84         public function __construct( array $params ) {
  85                 parent::__construct( $params );
  86                 $params['redisConfig']['serializer'] = 'none'; // make it easy to use Lua
  87                 $this->server = $params['redisServer'];
  88                 $this->compression = isset( $params['compression'] ) ? $params['compression'] : 'none';
  89                 $this->redisPool = RedisConnectionPool::singleton( $params['redisConfig'] );
  90         }
  91
  92         protected function supportedOrders() {
  93                 return array( 'timestamp', 'fifo' );
  94         }
  95
  96         protected function optimalOrder() {
  97                 return 'fifo';
  98         }
  99
 100         protected function supportsDelayedJobs() {
 101                 return true;
 102         }
 103
 104         /**
 105          * @see JobQueue::doIsEmpty()
 106          * @return bool
 107          * @throws MWException
 108          */
 109         protected function doIsEmpty() {
 110                 return $this->doGetSize() == 0;
 111         }
 112
 113         /**
 114          * @see JobQueue::doGetSize()
 115          * @return int
 116          * @throws MWException
 117          */
 118         protected function doGetSize() {
 119                 $conn = $this->getConnection();
 120                 try {
 121                         return $conn->lSize( $this->getQueueKey( 'l-unclaimed' ) );
 122                 } catch ( RedisException $e ) {
 123                         $this->throwRedisException( $conn, $e );
 124                 }
 125         }
 126
 127         /**
 128          * @see JobQueue::doGetAcquiredCount()
 129          * @return int
 130          * @throws JobQueueError
 131          */
 132         protected function doGetAcquiredCount() {
 133                 if ( $this->claimTTL <= 0 ) {
 134                         return 0; // no acknowledgements
 135                 }
 136                 $conn = $this->getConnection();
 137                 try {
 138                         $conn->multi( Redis::PIPELINE );
 139                         $conn->zSize( $this->getQueueKey( 'z-claimed' ) );
 140                         $conn->zSize( $this->getQueueKey( 'z-abandoned' ) );
 141
 142                         return array_sum( $conn->exec() );
 143                 } catch ( RedisException $e ) {
 144                         $this->throwRedisException( $conn, $e );
 145                 }
 146         }
 147
 148         /**
 149          * @see JobQueue::doGetDelayedCount()
 150          * @return int
 151          * @throws JobQueueError
 152          */
 153         protected function doGetDelayedCount() {
 154                 if ( !$this->checkDelay ) {
 155                         return 0; // no delayed jobs
 156                 }
 157                 $conn = $this->getConnection();
 158                 try {
 159                         return $conn->zSize( $this->getQueueKey( 'z-delayed' ) );
 160                 } catch ( RedisException $e ) {
 161                         $this->throwRedisException( $conn, $e );
 162                 }
 163         }
 164
 165         /**
 166          * @see JobQueue::doGetAbandonedCount()
 167          * @return int
 168          * @throws JobQueueError
 169          */
 170         protected function doGetAbandonedCount() {
 171                 if ( $this->claimTTL <= 0 ) {
 172                         return 0; // no acknowledgements
 173                 }
 174                 $conn = $this->getConnection();
 175                 try {
 176                         return $conn->zSize( $this->getQueueKey( 'z-abandoned' ) );
 177                 } catch ( RedisException $e ) {
 178                         $this->throwRedisException( $conn, $e );
 179                 }
 180         }
 181
 182         /**
 183          * @see JobQueue::doBatchPush()
 184          * @param array $jobs
 185          * @param int $flags
 186          * @return void
 187          * @throws JobQueueError
 188          */
 189         protected function doBatchPush( array $jobs, $flags ) {
 190                 // Convert the jobs into field maps (de-duplicated against each other)
 191                 $items = array(); // (job ID => job fields map)
 192                 foreach ( $jobs as $job ) {
 193                         $item = $this->getNewJobFields( $job );
 194                         if ( strlen( $item['sha1'] ) ) { // hash identifier => de-duplicate
 195                                 $items[$item['sha1']] = $item;
 196                         } else {
 197                                 $items[$item['uuid']] = $item;
 198                         }
 199                 }
 200
 201                 if ( !count( $items ) ) {
 202                         return; // nothing to do
 203                 }
 204
 205                 $conn = $this->getConnection();
 206                 try {
 207                         // Actually push the non-duplicate jobs into the queue...
 208                         if ( $flags & self::QOS_ATOMIC ) {
 209                                 $batches = array( $items ); // all or nothing
 210                         } else {
 211                                 $batches = array_chunk( $items, 500 ); // avoid tying up the server
 212                         }
 213                         $failed = 0;
 214                         $pushed = 0;
 215                         foreach ( $batches as $itemBatch ) {
 216                                 $added = $this->pushBlobs( $conn, $itemBatch );
 217                                 if ( is_int( $added ) ) {
 218                                         $pushed += $added;
 219                                 } else {
 220                                         $failed += count( $itemBatch );
 221                                 }
 222                         }
 223                         if ( $failed > 0 ) {
 224                                 wfDebugLog( 'JobQueueRedis', "Could not insert {$failed} {$this->type} job(s)." );
 225
 226                                 throw new RedisException( "Could not insert {$failed} {$this->type} job(s)." );
 227                         }
 228                         JobQueue::incrStats( 'job-insert', $this->type, count( $items ), $this->wiki );
 229                         JobQueue::incrStats( 'job-insert-duplicate', $this->type,
 230                                 count( $items ) - $failed - $pushed, $this->wiki );
 231                 } catch ( RedisException $e ) {
 232                         $this->throwRedisException( $conn, $e );
 233                 }
 234         }
 235
 236         /**
 237          * @param RedisConnRef $conn
 238          * @param array $items List of results from JobQueueRedis::getNewJobFields()
 239          * @return int Number of jobs inserted (duplicates are ignored)
 240          * @throws RedisException
 241          */
 242         protected function pushBlobs( RedisConnRef $conn, array $items ) {
 243                 $args = array(); // ([id, sha1, rtime, blob [, id, sha1, rtime, blob ... ] ] )
 244                 foreach ( $items as $item ) {
 245                         $args[] = (string)$item['uuid'];
 246                         $args[] = (string)$item['sha1'];
 247                         $args[] = (string)$item['rtimestamp'];
 248                         $args[] = (string)$this->serialize( $item );
 249                 }
 250                 static $script =
 251 <<<LUA
 252                 local kUnclaimed, kSha1ById, kIdBySha1, kDelayed, kData = unpack(KEYS)
 253                 if #ARGV % 4 ~= 0 then return redis.error_reply('Unmatched arguments') end
 254                 local pushed = 0
 255                 for i = 1,#ARGV,4 do
 256                         local id,sha1,rtimestamp,blob = ARGV[i],ARGV[i+1],ARGV[i+2],ARGV[i+3]
 257                         if sha1 == '' or redis.call('hExists',kIdBySha1,sha1) == 0 then
 258                                 if 1*rtimestamp > 0 then
 259                                         -- Insert into delayed queue (release time as score)
 260                                         redis.call('zAdd',kDelayed,rtimestamp,id)
 261                                 else
 262                                         -- Insert into unclaimed queue
 263                                         redis.call('lPush',kUnclaimed,id)
 264                                 end
 265                                 if sha1 ~= '' then
 266                                         redis.call('hSet',kSha1ById,id,sha1)
 267                                         redis.call('hSet',kIdBySha1,sha1,id)
 268                                 end
 269                                 redis.call('hSet',kData,id,blob)
 270                                 pushed = pushed + 1
 271                         end
 272                 end
 273                 return pushed
 274 LUA;
 275                 return $conn->luaEval( $script,
 276                         array_merge(
 277                                 array(
 278                                         $this->getQueueKey( 'l-unclaimed' ), # KEYS[1]
 279                                         $this->getQueueKey( 'h-sha1ById' ), # KEYS[2]
 280                                         $this->getQueueKey( 'h-idBySha1' ), # KEYS[3]
 281                                         $this->getQueueKey( 'z-delayed' ), # KEYS[4]
 282                                         $this->getQueueKey( 'h-data' ), # KEYS[5]
 283                                 ),
 284                                 $args
 285                         ),
 286                         5 # number of first argument(s) that are keys
 287                 );
 288         }
 289
 290         /**
 291          * @see JobQueue::doPop()
 292          * @return Job|bool
 293          * @throws JobQueueError
 294          */
 295         protected function doPop() {
 296                 $job = false;
 297
 298                 // Push ready delayed jobs into the queue every 10 jobs to spread the load.
 299                 // This is also done as a periodic task, but we don't want too much done at once.
 300                 if ( $this->checkDelay && mt_rand( 0, 9 ) == 0 ) {
 301                         $this->recyclePruneAndUndelayJobs();
 302                 }
 303
 304                 $conn = $this->getConnection();
 305                 try {
 306                         do {
 307                                 if ( $this->claimTTL > 0 ) {
 308                                         // Keep the claimed job list down for high-traffic queues
 309                                         if ( mt_rand( 0, 99 ) == 0 ) {
 310                                                 $this->recyclePruneAndUndelayJobs();
 311                                         }
 312                                         $blob = $this->popAndAcquireBlob( $conn );
 313                                 } else {
 314                                         $blob = $this->popAndDeleteBlob( $conn );
 315                                 }
 316                                 if ( $blob === false ) {
 317                                         break; // no jobs; nothing to do
 318                                 }
 319
 320                                 JobQueue::incrStats( 'job-pop', $this->type, 1, $this->wiki );
 321                                 $item = $this->unserialize( $blob );
 322                                 if ( $item === false ) {
 323                                         wfDebugLog( 'JobQueueRedis', "Could not unserialize {$this->type} job." );
 324                                         continue;
 325                                 }
 326
 327                                 // If $item is invalid, recyclePruneAndUndelayJobs() will cleanup as needed
 328                                 $job = $this->getJobFromFields( $item ); // may be false
 329                         } while ( !$job ); // job may be false if invalid
 330                 } catch ( RedisException $e ) {
 331                         $this->throwRedisException( $conn, $e );
 332                 }
 333
 334                 return $job;
 335         }
 336
 337         /**
 338          * @param RedisConnRef $conn
 339          * @return array Serialized string or false
 340          * @throws RedisException
 341          */
 342         protected function popAndDeleteBlob( RedisConnRef $conn ) {
 343                 static $script =
 344 <<<LUA
 345                 local kUnclaimed, kSha1ById, kIdBySha1, kData = unpack(KEYS)
 346                 -- Pop an item off the queue
 347                 local id = redis.call('rpop',kUnclaimed)
 348                 if not id then return false end
 349                 -- Get the job data and remove it
 350                 local item = redis.call('hGet',kData,id)
 351                 redis.call('hDel',kData,id)
 352                 -- Allow new duplicates of this job
 353                 local sha1 = redis.call('hGet',kSha1ById,id)
 354                 if sha1 then redis.call('hDel',kIdBySha1,sha1) end
 355                 redis.call('hDel',kSha1ById,id)
 356                 -- Return the job data
 357                 return item
 358 LUA;
 359                 return $conn->luaEval( $script,
 360                         array(
 361                                 $this->getQueueKey( 'l-unclaimed' ), # KEYS[1]
 362                                 $this->getQueueKey( 'h-sha1ById' ), # KEYS[2]
 363                                 $this->getQueueKey( 'h-idBySha1' ), # KEYS[3]
 364                                 $this->getQueueKey( 'h-data' ), # KEYS[4]
 365                         ),
 366                         4 # number of first argument(s) that are keys
 367                 );
 368         }
 369
 370         /**
 371          * @param RedisConnRef $conn
 372          * @return array Serialized string or false
 373          * @throws RedisException
 374          */
 375         protected function popAndAcquireBlob( RedisConnRef $conn ) {
 376                 static $script =
 377 <<<LUA
 378                 local kUnclaimed, kSha1ById, kIdBySha1, kClaimed, kAttempts, kData = unpack(KEYS)
 379                 -- Pop an item off the queue
 380                 local id = redis.call('rPop',kUnclaimed)
 381                 if not id then return false end
 382                 -- Allow new duplicates of this job
 383                 local sha1 = redis.call('hGet',kSha1ById,id)
 384                 if sha1 then redis.call('hDel',kIdBySha1,sha1) end
 385                 redis.call('hDel',kSha1ById,id)
 386                 -- Mark the jobs as claimed and return it
 387                 redis.call('zAdd',kClaimed,ARGV[1],id)
 388                 redis.call('hIncrBy',kAttempts,id,1)
 389                 return redis.call('hGet',kData,id)
 390 LUA;
 391                 return $conn->luaEval( $script,
 392                         array(
 393                                 $this->getQueueKey( 'l-unclaimed' ), # KEYS[1]
 394                                 $this->getQueueKey( 'h-sha1ById' ), # KEYS[2]
 395                                 $this->getQueueKey( 'h-idBySha1' ), # KEYS[3]
 396                                 $this->getQueueKey( 'z-claimed' ), # KEYS[4]
 397                                 $this->getQueueKey( 'h-attempts' ), # KEYS[5]
 398                                 $this->getQueueKey( 'h-data' ), # KEYS[6]
 399                                 time(), # ARGV[1] (injected to be replication-safe)
 400                         ),
 401                         6 # number of first argument(s) that are keys
 402                 );
 403         }
 404
 405         /**
 406          * @see JobQueue::doAck()
 407          * @param Job $job
 408          * @return Job|bool
 409          * @throws MWException|JobQueueError
 410          */
 411         protected function doAck( Job $job ) {
 412                 if ( !isset( $job->metadata['uuid'] ) ) {
 413                         throw new MWException( "Job of type '{$job->getType()}' has no UUID." );
 414                 }
 415                 if ( $this->claimTTL > 0 ) {
 416                         $conn = $this->getConnection();
 417                         try {
 418                                 static $script =
 419 <<<LUA
 420                                 local kClaimed, kAttempts, kData = unpack(KEYS)
 421                                 -- Unmark the job as claimed
 422                                 redis.call('zRem',kClaimed,ARGV[1])
 423                                 redis.call('hDel',kAttempts,ARGV[1])
 424                                 -- Delete the job data itself
 425                                 return redis.call('hDel',kData,ARGV[1])
 426 LUA;
 427                                 $res = $conn->luaEval( $script,
 428                                         array(
 429                                                 $this->getQueueKey( 'z-claimed' ), # KEYS[1]
 430                                                 $this->getQueueKey( 'h-attempts' ), # KEYS[2]
 431                                                 $this->getQueueKey( 'h-data' ), # KEYS[3]
 432                                                 $job->metadata['uuid'] # ARGV[1]
 433                                         ),
 434                                         3 # number of first argument(s) that are keys
 435                                 );
 436
 437                                 if ( !$res ) {
 438                                         wfDebugLog( 'JobQueueRedis', "Could not acknowledge {$this->type} job." );
 439
 440                                         return false;
 441                                 }
 442                         } catch ( RedisException $e ) {
 443                                 $this->throwRedisException( $conn, $e );
 444                         }
 445                 }
 446
 447                 return true;
 448         }
 449
 450         /**
 451          * @see JobQueue::doDeduplicateRootJob()
 452          * @param Job $job
 453          * @return bool
 454          * @throws MWException|JobQueueError
 455          */
 456         protected function doDeduplicateRootJob( Job $job ) {
 457                 if ( !$job->hasRootJobParams() ) {
 458                         throw new MWException( "Cannot register root job; missing parameters." );
 459                 }
 460                 $params = $job->getRootJobParams();
 461
 462                 $key = $this->getRootJobCacheKey( $params['rootJobSignature'] );
 463
 464                 $conn = $this->getConnection();
 465                 try {
 466                         $timestamp = $conn->get( $key ); // current last timestamp of this job
 467                         if ( $timestamp && $timestamp >= $params['rootJobTimestamp'] ) {
 468                                 return true; // a newer version of this root job was enqueued
 469                         }
 470
 471                         // Update the timestamp of the last root job started at the location...
 472                         return $conn->set( $key, $params['rootJobTimestamp'], self::ROOTJOB_TTL ); // 2 weeks
 473                 } catch ( RedisException $e ) {
 474                         $this->throwRedisException( $conn, $e );
 475                 }
 476         }
 477
 478         /**
 479          * @see JobQueue::doIsRootJobOldDuplicate()
 480          * @param Job $job
 481          * @return bool
 482          * @throws JobQueueError
 483          */
 484         protected function doIsRootJobOldDuplicate( Job $job ) {
 485                 if ( !$job->hasRootJobParams() ) {
 486                         return false; // job has no de-deplication info
 487                 }
 488                 $params = $job->getRootJobParams();
 489
 490                 $conn = $this->getConnection();
 491                 try {
 492                         // Get the last time this root job was enqueued
 493                         $timestamp = $conn->get( $this->getRootJobCacheKey( $params['rootJobSignature'] ) );
 494                 } catch ( RedisException $e ) {
 495                         $this->throwRedisException( $conn, $e );
 496                 }
 497
 498                 // Check if a new root job was started at the location after this one's...
 499                 return ( $timestamp && $timestamp > $params['rootJobTimestamp'] );
 500         }
 501
 502         /**
 503          * @see JobQueue::doDelete()
 504          * @return bool
 505          * @throws JobQueueError
 506          */
 507         protected function doDelete() {
 508                 static $props = array( 'l-unclaimed', 'z-claimed', 'z-abandoned',
 509                         'z-delayed', 'h-idBySha1', 'h-sha1ById', 'h-attempts', 'h-data' );
 510
 511                 $conn = $this->getConnection();
 512                 try {
 513                         $keys = array();
 514                         foreach ( $props as $prop ) {
 515                                 $keys[] = $this->getQueueKey( $prop );
 516                         }
 517
 518                         return ( $conn->delete( $keys ) !== false );
 519                 } catch ( RedisException $e ) {
 520                         $this->throwRedisException( $conn, $e );
 521                 }
 522         }
 523
 524         /**
 525          * @see JobQueue::getAllQueuedJobs()
 526          * @return Iterator
 527          */
 528         public function getAllQueuedJobs() {
 529                 $conn = $this->getConnection();
 530                 try {
 531                         $that = $this;
 532
 533                         return new MappedIterator(
 534                                 $conn->lRange( $this->getQueueKey( 'l-unclaimed' ), 0, -1 ),
 535                                 function ( $uid ) use ( $that, $conn ) {
 536                                         return $that->getJobFromUidInternal( $uid, $conn );
 537                                 },
 538                                 array( 'accept' => function ( $job ) {
 539                                         return is_object( $job );
 540                                 } )
 541                         );
 542                 } catch ( RedisException $e ) {
 543                         $this->throwRedisException( $conn, $e );
 544                 }
 545         }
 546
 547         /**
 548          * @see JobQueue::getAllQueuedJobs()
 549          * @return Iterator
 550          */
 551         public function getAllDelayedJobs() {
 552                 $conn = $this->getConnection();
 553                 try {
 554                         $that = $this;
 555
 556                         return new MappedIterator( // delayed jobs
 557                                 $conn->zRange( $this->getQueueKey( 'z-delayed' ), 0, -1 ),
 558                                 function ( $uid ) use ( $that, $conn ) {
 559                                         return $that->getJobFromUidInternal( $uid, $conn );
 560                                 },
 561                                 array( 'accept' => function ( $job ) {
 562                                         return is_object( $job );
 563                                 } )
 564                         );
 565                 } catch ( RedisException $e ) {
 566                         $this->throwRedisException( $conn, $e );
 567                 }
 568         }
 569
 570         public function getCoalesceLocationInternal() {
 571                 return "RedisServer:" . $this->server;
 572         }
 573
 574         protected function doGetSiblingQueuesWithJobs( array $types ) {
 575                 return array_keys( array_filter( $this->doGetSiblingQueueSizes( $types ) ) );
 576         }
 577
 578         protected function doGetSiblingQueueSizes( array $types ) {
 579                 $sizes = array(); // (type => size)
 580                 $types = array_values( $types ); // reindex
 581                 $conn = $this->getConnection();
 582                 try {
 583                         $conn->multi( Redis::PIPELINE );
 584                         foreach ( $types as $type ) {
 585                                 $conn->lSize( $this->getQueueKey( 'l-unclaimed', $type ) );
 586                         }
 587                         $res = $conn->exec();
 588                         if ( is_array( $res ) ) {
 589                                 foreach ( $res as $i => $size ) {
 590                                         $sizes[$types[$i]] = $size;
 591                                 }
 592                         }
 593                 } catch ( RedisException $e ) {
 594                         $this->throwRedisException( $conn, $e );
 595                 }
 596
 597                 return $sizes;
 598         }
 599
 600         /**
 601          * This function should not be called outside JobQueueRedis
 602          *
 603          * @param string $uid
 604          * @param RedisConnRef $conn
 605          * @return Job|bool Returns false if the job does not exist
 606          * @throws MWException|JobQueueError
 607          */
 608         public function getJobFromUidInternal( $uid, RedisConnRef $conn ) {
 609                 try {
 610                         $data = $conn->hGet( $this->getQueueKey( 'h-data' ), $uid );
 611                         if ( $data === false ) {
 612                                 return false; // not found
 613                         }
 614                         $item = $this->unserialize( $conn->hGet( $this->getQueueKey( 'h-data' ), $uid ) );
 615                         if ( !is_array( $item ) ) { // this shouldn't happen
 616                                 throw new MWException( "Could not find job with ID '$uid'." );
 617                         }
 618                         $title = Title::makeTitle( $item['namespace'], $item['title'] );
 619                         $job = Job::factory( $item['type'], $title, $item['params'] );
 620                         $job->metadata['uuid'] = $item['uuid'];
 621
 622                         return $job;
 623                 } catch ( RedisException $e ) {
 624                         $this->throwRedisException( $conn, $e );
 625                 }
 626         }
 627
 628         /**
 629          * Recycle or destroy any jobs that have been claimed for too long
 630          * and release any ready delayed jobs into the queue
 631          *
 632          * @return int Number of jobs recycled/deleted/undelayed
 633          * @throws MWException|JobQueueError
 634          */
 635         public function recyclePruneAndUndelayJobs() {
 636                 $count = 0;
 637                 // For each job item that can be retried, we need to add it back to the
 638                 // main queue and remove it from the list of currenty claimed job items.
 639                 // For those that cannot, they are marked as dead and kept around for
 640                 // investigation and manual job restoration but are eventually deleted.
 641                 $conn = $this->getConnection();
 642                 try {
 643                         $now = time();
 644                         static $script =
 645 <<<LUA
 646                         local kClaimed, kAttempts, kUnclaimed, kData, kAbandoned, kDelayed = unpack(KEYS)
 647                         local released,abandoned,pruned,undelayed = 0,0,0,0
 648                         -- Get all non-dead jobs that have an expired claim on them.
 649                         -- The score for each item is the last claim timestamp (UNIX).
 650                         local staleClaims = redis.call('zRangeByScore',kClaimed,0,ARGV[1])
 651                         for k,id in ipairs(staleClaims) do
 652                                 local timestamp = redis.call('zScore',kClaimed,id)
 653                                 local attempts = redis.call('hGet',kAttempts,id)
 654                                 if attempts < ARGV[3] then
 655                                         -- Claim expired and retries left: re-enqueue the job
 656                                         redis.call('lPush',kUnclaimed,id)
 657                                         redis.call('hIncrBy',kAttempts,id,1)
 658                                         released = released + 1
 659                                 else
 660                                         -- Claim expired and no retries left: mark the job as dead
 661                                         redis.call('zAdd',kAbandoned,timestamp,id)
 662                                         abandoned = abandoned + 1
 663                                 end
 664                                 redis.call('zRem',kClaimed,id)
 665                         end
 666                         -- Get all of the dead jobs that have been marked as dead for too long.
 667                         -- The score for each item is the last claim timestamp (UNIX).
 668                         local deadClaims = redis.call('zRangeByScore',kAbandoned,0,ARGV[2])
 669                         for k,id in ipairs(deadClaims) do
 670                                 -- Stale and out of retries: remove any traces of the job
 671                                 redis.call('zRem',kAbandoned,id)
 672                                 redis.call('hDel',kAttempts,id)
 673                                 redis.call('hDel',kData,id)
 674                                 pruned = pruned + 1
 675                         end
 676                         -- Get the list of ready delayed jobs, sorted by readiness (UNIX timestamp)
 677                         local ids = redis.call('zRangeByScore',kDelayed,0,ARGV[4])
 678                         -- Migrate the jobs from the "delayed" set to the "unclaimed" list
 679                         for k,id in ipairs(ids) do
 680                                 redis.call('lPush',kUnclaimed,id)
 681                                 redis.call('zRem',kDelayed,id)
 682                         end
 683                         undelayed = #ids
 684                         return {released,abandoned,pruned,undelayed}
 685 LUA;
 686                         $res = $conn->luaEval( $script,
 687                                 array(
 688                                         $this->getQueueKey( 'z-claimed' ), # KEYS[1]
 689                                         $this->getQueueKey( 'h-attempts' ), # KEYS[2]
 690                                         $this->getQueueKey( 'l-unclaimed' ), # KEYS[3]
 691                                         $this->getQueueKey( 'h-data' ), # KEYS[4]
 692                                         $this->getQueueKey( 'z-abandoned' ), # KEYS[5]
 693                                         $this->getQueueKey( 'z-delayed' ), # KEYS[6]
 694                                         $now - $this->claimTTL, # ARGV[1]
 695                                         $now - self::MAX_AGE_PRUNE, # ARGV[2]
 696                                         $this->maxTries, # ARGV[3]
 697                                         $now # ARGV[4]
 698                                 ),
 699                                 6 # number of first argument(s) that are keys
 700                         );
 701                         if ( $res ) {
 702                                 list( $released, $abandoned, $pruned, $undelayed ) = $res;
 703                                 $count += $released + $pruned + $undelayed;
 704                                 JobQueue::incrStats( 'job-recycle', $this->type, $released, $this->wiki );
 705                                 JobQueue::incrStats( 'job-abandon', $this->type, $abandoned, $this->wiki );
 706                         }
 707                 } catch ( RedisException $e ) {
 708                         $this->throwRedisException( $conn, $e );
 709                 }
 710
 711                 return $count;
 712         }
 713
 714         /**
 715          * @return array
 716          */
 717         protected function doGetPeriodicTasks() {
 718                 $periods = array( 3600 ); // standard cleanup (useful on config change)
 719                 if ( $this->claimTTL > 0 ) {
 720                         $periods[] = ceil( $this->claimTTL / 2 ); // avoid bad timing
 721                 }
 722                 if ( $this->checkDelay ) {
 723                         $periods[] = 300; // 5 minutes
 724                 }
 725                 $period = min( $periods );
 726                 $period = max( $period, 30 ); // sanity
 727
 728                 return array(
 729                         'recyclePruneAndUndelayJobs' => array(
 730                                 'callback' => array( $this, 'recyclePruneAndUndelayJobs' ),
 731                                 'period'   => $period,
 732                         )
 733                 );
 734         }
 735
 736         /**
 737          * @param IJobSpecification $job
 738          * @return array
 739          */
 740         protected function getNewJobFields( IJobSpecification $job ) {
 741                 return array(
 742                         // Fields that describe the nature of the job
 743                         'type' => $job->getType(),
 744                         'namespace' => $job->getTitle()->getNamespace(),
 745                         'title' => $job->getTitle()->getDBkey(),
 746                         'params' => $job->getParams(),
 747                         // Some jobs cannot run until a "release timestamp"
 748                         'rtimestamp' => $job->getReleaseTimestamp() ?: 0,
 749                         // Additional job metadata
 750                         'uuid' => UIDGenerator::newRawUUIDv4( UIDGenerator::QUICK_RAND ),
 751                         'sha1' => $job->ignoreDuplicates()
 752                                 ? wfBaseConvert( sha1( serialize( $job->getDeduplicationInfo() ) ), 16, 36, 31 )
 753                                 : '',
 754                         'timestamp' => time() // UNIX timestamp
 755                 );
 756         }
 757
 758         /**
 759          * @param array $fields
 760          * @return Job|bool
 761          */
 762         protected function getJobFromFields( array $fields ) {
 763                 $title = Title::makeTitleSafe( $fields['namespace'], $fields['title'] );
 764                 if ( $title ) {
 765                         $job = Job::factory( $fields['type'], $title, $fields['params'] );
 766                         $job->metadata['uuid'] = $fields['uuid'];
 767
 768                         return $job;
 769                 }
 770
 771                 return false;
 772         }
 773
 774         /**
 775          * @param array $fields
 776          * @return string Serialized and possibly compressed version of $fields
 777          */
 778         protected function serialize( array $fields ) {
 779                 $blob = serialize( $fields );
 780                 if ( $this->compression === 'gzip'
 781                         && strlen( $blob ) >= 1024
 782                         && function_exists( 'gzdeflate' )
 783                 ) {
 784                         $object = (object)array( 'blob' => gzdeflate( $blob ), 'enc' => 'gzip' );
 785                         $blobz = serialize( $object );
 786
 787                         return ( strlen( $blobz ) < strlen( $blob ) ) ? $blobz : $blob;
 788                 } else {
 789                         return $blob;
 790                 }
 791         }
 792
 793         /**
 794          * @param string $blob
 795          * @return array|bool Unserialized version of $blob or false
 796          */
 797         protected function unserialize( $blob ) {
 798                 $fields = unserialize( $blob );
 799                 if ( is_object( $fields ) ) {
 800                         if ( $fields->enc === 'gzip' && function_exists( 'gzinflate' ) ) {
 801                                 $fields = unserialize( gzinflate( $fields->blob ) );
 802                         } else {
 803                                 $fields = false;
 804                         }
 805                 }
 806
 807                 return is_array( $fields ) ? $fields : false;
 808         }
 809
 810         /**
 811          * Get a connection to the server that handles all sub-queues for this queue
 812          *
 813          * @return RedisConnRef
 814          * @throws JobQueueConnectionError
 815          */
 816         protected function getConnection() {
 817                 $conn = $this->redisPool->getConnection( $this->server );
 818                 if ( !$conn ) {
 819                         throw new JobQueueConnectionError( "Unable to connect to redis server." );
 820                 }
 821
 822                 return $conn;
 823         }
 824
 825         /**
 826          * @param RedisConnRef $conn
 827          * @param RedisException $e
 828          * @throws JobQueueError
 829          */
 830         protected function throwRedisException( RedisConnRef $conn, $e ) {
 831                 $this->redisPool->handleError( $conn, $e );
 832                 throw new JobQueueError( "Redis server error: {$e->getMessage()}\n" );
 833         }
 834
 835         /**
 836          * @param string $prop
 837          * @param string|null $type
 838          * @return string
 839          */
 840         private function getQueueKey( $prop, $type = null ) {
 841                 $type = is_string( $type ) ? $type : $this->type;
 842                 list( $db, $prefix ) = wfSplitWikiID( $this->wiki );
 843                 if ( strlen( $this->key ) ) { // namespaced queue (for testing)
 844                         return wfForeignMemcKey( $db, $prefix, 'jobqueue', $type, $this->key, $prop );
 845                 } else {
 846                         return wfForeignMemcKey( $db, $prefix, 'jobqueue', $type, $prop );
 847                 }
 848         }
 849
 850         /**
 851          * @param string $key
 852          * @return void
 853          */
 854         public function setTestingPrefix( $key ) {
 855                 $this->key = $key;
 856         }
 857 }