includes/job/JobQueueRedis.php

   1 <?php
   2 /**
   3  * Redis-backed job queue code.
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18  * http://www.gnu.org/copyleft/gpl.html
  19  *
  20  * @file
  21  * @author Aaron Schulz
  22  */
  23
  24 /**
  25  * Class to handle job queues stored in Redis
  26  *
  27  * This is faster, less resource intensive, queue that JobQueueDB.
  28  * All data for a queue using this class is placed into one redis server.
  29  *
  30  * There are eight main redis keys used to track jobs:
  31  *   - l-unclaimed  : A list of job IDs used for ready unclaimed jobs
  32  *   - z-claimed    : A sorted set of (job ID, UNIX timestamp as score) used for job retries
  33  *   - z-abandoned  : A sorted set of (job ID, UNIX timestamp as score) used for broken jobs
  34  *   - z-delayed    : A sorted set of (job ID, UNIX timestamp as score) used for delayed jobs
  35  *   - h-idBySha1   : A hash of (SHA1 => job ID) for unclaimed jobs used for de-duplication
  36  *   - h-sha1ById   : A hash of (job ID => SHA1) for unclaimed jobs used for de-duplication
  37  *   - h-attempts   : A hash of (job ID => attempt count) used for job claiming/retries
  38  *   - h-data       : A hash of (job ID => serialized blobs) for job storage
  39  * A job ID can be in only one of z-delayed, l-unclaimed, z-claimed, and z-abandoned.
  40  * If an ID appears in any of those lists, it should have a h-data entry for its ID.
  41  * If a job has a SHA1 de-duplication value and its ID is in l-unclaimed or z-delayed, then
  42  * there should be no other such jobs with that SHA1. Every h-idBySha1 entry has an h-sha1ById
  43  * entry and every h-sha1ById must refer to an ID that is l-unclaimed. If a job has its
  44  * ID in z-claimed or z-abandoned, then it must also have an h-attempts entry for its ID.
  45  *
  46  * Additionally, "rootjob:* keys track "root jobs" used for additional de-duplication.
  47  * Aside from root job keys, all keys have no expiry, and are only removed when jobs are run.
  48  * All the keys are prefixed with the relevant wiki ID information.
  49  *
  50  * This class requires Redis 2.6 as it makes use Lua scripts for fast atomic operations.
  51  * Additionally, it should be noted that redis has different persistence modes, such
  52  * as rdb snapshots, journaling, and no persistent. Appropriate configuration should be
  53  * made on the servers based on what queues are using it and what tolerance they have.
  54  *
  55  * @ingroup JobQueue
  56  * @ingroup Redis
  57  * @since 1.22
  58  */
  59 class JobQueueRedis extends JobQueue {
  60         /** @var RedisConnectionPool */
  61         protected $redisPool;
  62
  63         protected $server; // string; server address
  64         protected $compression; // string; compression method to use
  65
  66         const MAX_AGE_PRUNE = 604800; // integer; seconds a job can live once claimed (7 days)
  67
  68         protected $key; // string; key to prefix the queue keys with (used for testing)
  69
  70         /**
  71          * @params include:
  72          *   - redisConfig : An array of parameters to RedisConnectionPool::__construct().
  73          *                   Note that the serializer option is ignored as "none" is always used.
  74          *   - redisServer : A hostname/port combination or the absolute path of a UNIX socket.
  75          *                   If a hostname is specified but no port, the standard port number
  76          *                   6379 will be used. Required.
  77          *   - compression : The type of compression to use; one of (none,gzip).
  78          * @param array $params
  79          */
  80         public function __construct( array $params ) {
  81                 parent::__construct( $params );
  82                 $params['redisConfig']['serializer'] = 'none'; // make it easy to use Lua
  83                 $this->server = $params['redisServer'];
  84                 $this->compression = isset( $params['compression'] ) ? $params['compression'] : 'none';
  85                 $this->redisPool = RedisConnectionPool::singleton( $params['redisConfig'] );
  86         }
  87
  88         protected function supportedOrders() {
  89                 return array( 'timestamp', 'fifo' );
  90         }
  91
  92         protected function optimalOrder() {
  93                 return 'fifo';
  94         }
  95
  96         protected function supportsDelayedJobs() {
  97                 return true;
  98         }
  99
 100         /**
 101          * @see JobQueue::doIsEmpty()
 102          * @return bool
 103          * @throws MWException
 104          */
 105         protected function doIsEmpty() {
 106                 return $this->doGetSize() == 0;
 107         }
 108
 109         /**
 110          * @see JobQueue::doGetSize()
 111          * @return integer
 112          * @throws MWException
 113          */
 114         protected function doGetSize() {
 115                 $conn = $this->getConnection();
 116                 try {
 117                         return $conn->lSize( $this->getQueueKey( 'l-unclaimed' ) );
 118                 } catch ( RedisException $e ) {
 119                         $this->throwRedisException( $this->server, $conn, $e );
 120                 }
 121         }
 122
 123         /**
 124          * @see JobQueue::doGetAcquiredCount()
 125          * @return integer
 126          * @throws MWException
 127          */
 128         protected function doGetAcquiredCount() {
 129                 if ( $this->claimTTL <= 0 ) {
 130                         return 0; // no acknowledgements
 131                 }
 132                 $conn = $this->getConnection();
 133                 try {
 134                         $conn->multi( Redis::PIPELINE );
 135                         $conn->zSize( $this->getQueueKey( 'z-claimed' ) );
 136                         $conn->zSize( $this->getQueueKey( 'z-abandoned' ) );
 137
 138                         return array_sum( $conn->exec() );
 139                 } catch ( RedisException $e ) {
 140                         $this->throwRedisException( $this->server, $conn, $e );
 141                 }
 142         }
 143
 144         /**
 145          * @see JobQueue::doGetDelayedCount()
 146          * @return integer
 147          * @throws MWException
 148          */
 149         protected function doGetDelayedCount() {
 150                 if ( !$this->checkDelay ) {
 151                         return 0; // no delayed jobs
 152                 }
 153                 $conn = $this->getConnection();
 154                 try {
 155                         return $conn->zSize( $this->getQueueKey( 'z-delayed' ) );
 156                 } catch ( RedisException $e ) {
 157                         $this->throwRedisException( $this->server, $conn, $e );
 158                 }
 159         }
 160
 161         /**
 162          * @see JobQueue::doGetAbandonedCount()
 163          * @return integer
 164          * @throws MWException
 165          */
 166         protected function doGetAbandonedCount() {
 167                 if ( $this->claimTTL <= 0 ) {
 168                         return 0; // no acknowledgements
 169                 }
 170                 $conn = $this->getConnection();
 171                 try {
 172                         return $conn->zSize( $this->getQueueKey( 'z-abandoned' ) );
 173                 } catch ( RedisException $e ) {
 174                         $this->throwRedisException( $this->server, $conn, $e );
 175                 }
 176         }
 177
 178         /**
 179          * @see JobQueue::doBatchPush()
 180          * @param array $jobs
 181          * @param $flags
 182          * @return bool
 183          * @throws MWException
 184          */
 185         protected function doBatchPush( array $jobs, $flags ) {
 186                 // Convert the jobs into field maps (de-duplicated against each other)
 187                 $items = array(); // (job ID => job fields map)
 188                 foreach ( $jobs as $job ) {
 189                         $item = $this->getNewJobFields( $job );
 190                         if ( strlen( $item['sha1'] ) ) { // hash identifier => de-duplicate
 191                                 $items[$item['sha1']] = $item;
 192                         } else {
 193                                 $items[$item['uuid']] = $item;
 194                         }
 195                 }
 196
 197                 if ( !count( $items ) ) {
 198                         return true; // nothing to do
 199                 }
 200
 201                 $conn = $this->getConnection();
 202                 try {
 203                         // Actually push the non-duplicate jobs into the queue...
 204                         if ( $flags & self::QOS_ATOMIC ) {
 205                                 $batches = array( $items ); // all or nothing
 206                         } else {
 207                                 $batches = array_chunk( $items, 500 ); // avoid tying up the server
 208                         }
 209                         $failed = 0;
 210                         $pushed = 0;
 211                         foreach ( $batches as $itemBatch ) {
 212                                 $added = $this->pushBlobs( $conn, $itemBatch );
 213                                 if ( is_int( $added ) ) {
 214                                         $pushed += $added;
 215                                 } else {
 216                                         $failed += count( $itemBatch );
 217                                 }
 218                         }
 219                         if ( $failed > 0 ) {
 220                                 wfDebugLog( 'JobQueueRedis', "Could not insert {$failed} {$this->type} job(s)." );
 221
 222                                 return false;
 223                         }
 224                         JobQueue::incrStats( 'job-insert', $this->type, count( $items ) );
 225                         JobQueue::incrStats( 'job-insert-duplicate', $this->type,
 226                                 count( $items ) - $failed - $pushed );
 227                 } catch ( RedisException $e ) {
 228                         $this->throwRedisException( $this->server, $conn, $e );
 229                 }
 230
 231                 return true;
 232         }
 233
 234         /**
 235          * @param RedisConnRef $conn
 236          * @param array $items List of results from JobQueueRedis::getNewJobFields()
 237          * @return integer 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                 if #ARGV % 4 ~= 0 then return redis.error_reply('Unmatched arguments') end
 251                 local pushed = 0
 252                 for i = 1,#ARGV,4 do
 253                         local id,sha1,rtimestamp,blob = ARGV[i],ARGV[i+1],ARGV[i+2],ARGV[i+3]
 254                         if sha1 == '' or redis.call('hExists',KEYS[3],sha1) == 0 then
 255                                 if 1*rtimestamp > 0 then
 256                                         -- Insert into delayed queue (release time as score)
 257                                         redis.call('zAdd',KEYS[4],rtimestamp,id)
 258                                 else
 259                                         -- Insert into unclaimed queue
 260                                         redis.call('lPush',KEYS[1],id)
 261                                 end
 262                                 if sha1 ~= '' then
 263                                         redis.call('hSet',KEYS[2],id,sha1)
 264                                         redis.call('hSet',KEYS[3],sha1,id)
 265                                 end
 266                                 redis.call('hSet',KEYS[5],id,blob)
 267                                 pushed = pushed + 1
 268                         end
 269                 end
 270                 return pushed
 271 LUA;
 272                 return $conn->luaEval( $script,
 273                         array_merge(
 274                                 array(
 275                                         $this->getQueueKey( 'l-unclaimed' ), # KEYS[1]
 276                                         $this->getQueueKey( 'h-sha1ById' ), # KEYS[2]
 277                                         $this->getQueueKey( 'h-idBySha1' ), # KEYS[3]
 278                                         $this->getQueueKey( 'z-delayed' ), # KEYS[4]
 279                                         $this->getQueueKey( 'h-data' ), # KEYS[5]
 280                                 ),
 281                                 $args
 282                         ),
 283                         5 # number of first argument(s) that are keys
 284                 );
 285         }
 286
 287         /**
 288          * @see JobQueue::doPop()
 289          * @return Job|bool
 290          * @throws MWException
 291          */
 292         protected function doPop() {
 293                 $job = false;
 294
 295                 // Push ready delayed jobs into the queue every 10 jobs to spread the load.
 296                 // This is also done as a periodic task, but we don't want too much done at once.
 297                 if ( $this->checkDelay && mt_rand( 0, 9 ) == 0 ) {
 298                         $this->releaseReadyDelayedJobs();
 299                 }
 300
 301                 $conn = $this->getConnection();
 302                 try {
 303                         do {
 304                                 if ( $this->claimTTL > 0 ) {
 305                                         // Keep the claimed job list down for high-traffic queues
 306                                         if ( mt_rand( 0, 99 ) == 0 ) {
 307                                                 $this->recycleAndDeleteStaleJobs();
 308                                         }
 309                                         $blob = $this->popAndAcquireBlob( $conn );
 310                                 } else {
 311                                         $blob = $this->popAndDeleteBlob( $conn );
 312                                 }
 313                                 if ( $blob === false ) {
 314                                         break; // no jobs; nothing to do
 315                                 }
 316
 317                                 JobQueue::incrStats( 'job-pop', $this->type );
 318                                 $item = $this->unserialize( $blob );
 319                                 if ( $item === false ) {
 320                                         wfDebugLog( 'JobQueueRedis', "Could not unserialize {$this->type} job." );
 321                                         continue;
 322                                 }
 323
 324                                 // If $item is invalid, recycleAndDeleteStaleJobs() will cleanup as needed
 325                                 $job = $this->getJobFromFields( $item ); // may be false
 326                         } while ( !$job ); // job may be false if invalid
 327                 } catch ( RedisException $e ) {
 328                         $this->throwRedisException( $this->server, $conn, $e );
 329                 }
 330
 331                 return $job;
 332         }
 333
 334         /**
 335          * @param RedisConnRef $conn
 336          * @return array serialized string or false
 337          * @throws RedisException
 338          */
 339         protected function popAndDeleteBlob( RedisConnRef $conn ) {
 340                 static $script =
 341 <<<LUA
 342                 -- Pop an item off the queue
 343                 local id = redis.call('rpop',KEYS[1])
 344                 if not id then return false end
 345                 -- Get the job data and remove it
 346                 local item = redis.call('hGet',KEYS[4],id)
 347                 redis.call('hDel',KEYS[4],id)
 348                 -- Allow new duplicates of this job
 349                 local sha1 = redis.call('hGet',KEYS[2],id)
 350                 if sha1 then redis.call('hDel',KEYS[3],sha1) end
 351                 redis.call('hDel',KEYS[2],id)
 352                 -- Return the job data
 353                 return item
 354 LUA;
 355                 return $conn->luaEval( $script,
 356                         array(
 357                                 $this->getQueueKey( 'l-unclaimed' ), # KEYS[1]
 358                                 $this->getQueueKey( 'h-sha1ById' ), # KEYS[2]
 359                                 $this->getQueueKey( 'h-idBySha1' ), # KEYS[3]
 360                                 $this->getQueueKey( 'h-data' ), # KEYS[4]
 361                         ),
 362                         4 # number of first argument(s) that are keys
 363                 );
 364         }
 365
 366         /**
 367          * @param RedisConnRef $conn
 368          * @return array serialized string or false
 369          * @throws RedisException
 370          */
 371         protected function popAndAcquireBlob( RedisConnRef $conn ) {
 372                 static $script =
 373 <<<LUA
 374                 -- Pop an item off the queue
 375                 local id = redis.call('rPop',KEYS[1])
 376                 if not id then return false end
 377                 -- Allow new duplicates of this job
 378                 local sha1 = redis.call('hGet',KEYS[2],id)
 379                 if sha1 then redis.call('hDel',KEYS[3],sha1) end
 380                 redis.call('hDel',KEYS[2],id)
 381                 -- Mark the jobs as claimed and return it
 382                 redis.call('zAdd',KEYS[4],ARGV[1],id)
 383                 redis.call('hIncrBy',KEYS[5],id,1)
 384                 return redis.call('hGet',KEYS[6],id)
 385 LUA;
 386                 return $conn->luaEval( $script,
 387                         array(
 388                                 $this->getQueueKey( 'l-unclaimed' ), # KEYS[1]
 389                                 $this->getQueueKey( 'h-sha1ById' ), # KEYS[2]
 390                                 $this->getQueueKey( 'h-idBySha1' ), # KEYS[3]
 391                                 $this->getQueueKey( 'z-claimed' ), # KEYS[4]
 392                                 $this->getQueueKey( 'h-attempts' ), # KEYS[5]
 393                                 $this->getQueueKey( 'h-data' ), # KEYS[6]
 394                                 time(), # ARGV[1] (injected to be replication-safe)
 395                         ),
 396                         6 # number of first argument(s) that are keys
 397                 );
 398         }
 399
 400         /**
 401          * @see JobQueue::doAck()
 402          * @param Job $job
 403          * @return Job|bool
 404          * @throws MWException
 405          */
 406         protected function doAck( Job $job ) {
 407                 if ( !isset( $job->metadata['uuid'] ) ) {
 408                         throw new MWException( "Job of type '{$job->getType()}' has no UUID." );
 409                 }
 410                 if ( $this->claimTTL > 0 ) {
 411                         $conn = $this->getConnection();
 412                         try {
 413                                 static $script =
 414 <<<LUA
 415                                 -- Unmark the job as claimed
 416                                 redis.call('zRem',KEYS[1],ARGV[1])
 417                                 redis.call('hDel',KEYS[2],ARGV[1])
 418                                 -- Delete the job data itself
 419                                 return redis.call('hDel',KEYS[3],ARGV[1])
 420 LUA;
 421                                 $res = $conn->luaEval( $script,
 422                                         array(
 423                                                 $this->getQueueKey( 'z-claimed' ), # KEYS[1]
 424                                                 $this->getQueueKey( 'h-attempts' ), # KEYS[2]
 425                                                 $this->getQueueKey( 'h-data' ), # KEYS[3]
 426                                                 $job->metadata['uuid'] # ARGV[1]
 427                                         ),
 428                                         3 # number of first argument(s) that are keys
 429                                 );
 430
 431                                 if ( !$res ) {
 432                                         wfDebugLog( 'JobQueueRedis', "Could not acknowledge {$this->type} job." );
 433
 434                                         return false;
 435                                 }
 436                         } catch ( RedisException $e ) {
 437                                 $this->throwRedisException( $this->server, $conn, $e );
 438                         }
 439                 }
 440
 441                 return true;
 442         }
 443
 444         /**
 445          * @see JobQueue::doDeduplicateRootJob()
 446          * @param Job $job
 447          * @return bool
 448          * @throws MWException
 449          */
 450         protected function doDeduplicateRootJob( Job $job ) {
 451                 if ( !$job->hasRootJobParams() ) {
 452                         throw new MWException( "Cannot register root job; missing parameters." );
 453                 }
 454                 $params = $job->getRootJobParams();
 455
 456                 $key = $this->getRootJobCacheKey( $params['rootJobSignature'] );
 457
 458                 $conn = $this->getConnection();
 459                 try {
 460                         $timestamp = $conn->get( $key ); // current last timestamp of this job
 461                         if ( $timestamp && $timestamp >= $params['rootJobTimestamp'] ) {
 462                                 return true; // a newer version of this root job was enqueued
 463                         }
 464
 465                         // Update the timestamp of the last root job started at the location...
 466                         return $conn->set( $key, $params['rootJobTimestamp'], self::ROOTJOB_TTL ); // 2 weeks
 467                 } catch ( RedisException $e ) {
 468                         $this->throwRedisException( $this->server, $conn, $e );
 469                 }
 470         }
 471
 472         /**
 473          * @see JobQueue::doIsRootJobOldDuplicate()
 474          * @param Job $job
 475          * @return bool
 476          */
 477         protected function doIsRootJobOldDuplicate( Job $job ) {
 478                 if ( !$job->hasRootJobParams() ) {
 479                         return false; // job has no de-deplication info
 480                 }
 481                 $params = $job->getRootJobParams();
 482
 483                 $conn = $this->getConnection();
 484                 try {
 485                         // Get the last time this root job was enqueued
 486                         $timestamp = $conn->get( $this->getRootJobCacheKey( $params['rootJobSignature'] ) );
 487                 } catch ( RedisException $e ) {
 488                         $this->throwRedisException( $this->server, $conn, $e );
 489                 }
 490
 491                 // Check if a new root job was started at the location after this one's...
 492                 return ( $timestamp && $timestamp > $params['rootJobTimestamp'] );
 493         }
 494
 495         /**
 496          * @see JobQueue::doDelete()
 497          * @return bool
 498          */
 499         protected function doDelete() {
 500                 static $props = array( 'l-unclaimed', 'z-claimed', 'z-abandoned',
 501                         'z-delayed', 'h-idBySha1', 'h-sha1ById', 'h-attempts', 'h-data' );
 502
 503                 $conn = $this->getConnection();
 504                 try {
 505                         $keys = array();
 506                         foreach ( $props as $prop ) {
 507                                 $keys[] = $this->getQueueKey( $prop );
 508                         }
 509
 510                         return ( $conn->delete( $keys ) !== false );
 511                 } catch ( RedisException $e ) {
 512                         $this->throwRedisException( $this->server, $conn, $e );
 513                 }
 514         }
 515
 516         /**
 517          * @see JobQueue::getAllQueuedJobs()
 518          * @return Iterator
 519          */
 520         public function getAllQueuedJobs() {
 521                 $conn = $this->getConnection();
 522                 try {
 523                         $that = $this;
 524
 525                         return new MappedIterator(
 526                                 $conn->lRange( $this->getQueueKey( 'l-unclaimed' ), 0, -1 ),
 527                                 function ( $uid ) use ( $that, $conn ) {
 528                                         return $that->getJobFromUidInternal( $uid, $conn );
 529                                 },
 530                                 array( 'accept' => function ( $job ) {
 531                                         return is_object( $job );
 532                                 } )
 533                         );
 534                 } catch ( RedisException $e ) {
 535                         $this->throwRedisException( $this->server, $conn, $e );
 536                 }
 537         }
 538
 539         /**
 540          * @see JobQueue::getAllQueuedJobs()
 541          * @return Iterator
 542          */
 543         public function getAllDelayedJobs() {
 544                 $conn = $this->getConnection();
 545                 try {
 546                         $that = $this;
 547
 548                         return new MappedIterator( // delayed jobs
 549                                 $conn->zRange( $this->getQueueKey( 'z-delayed' ), 0, -1 ),
 550                                 function ( $uid ) use ( $that, $conn ) {
 551                                         return $that->getJobFromUidInternal( $uid, $conn );
 552                                 },
 553                                 array( 'accept' => function ( $job ) {
 554                                         return is_object( $job );
 555                                 } )
 556                         );
 557                 } catch ( RedisException $e ) {
 558                         $this->throwRedisException( $this->server, $conn, $e );
 559                 }
 560         }
 561
 562         public function getCoalesceLocationInternal() {
 563                 return "RedisServer:" . $this->server;
 564         }
 565
 566         protected function doGetSiblingQueuesWithJobs( array $types ) {
 567                 return array_keys( array_filter( $this->doGetSiblingQueueSizes( $types ) ) );
 568         }
 569
 570         protected function doGetSiblingQueueSizes( array $types ) {
 571                 $sizes = array(); // (type => size)
 572                 $types = array_values( $types ); // reindex
 573                 try {
 574                         $conn = $this->getConnection();
 575                         $conn->multi( Redis::PIPELINE );
 576                         foreach ( $types as $type ) {
 577                                 $conn->lSize( $this->getQueueKey( 'l-unclaimed', $type ) );
 578                         }
 579                         $res = $conn->exec();
 580                         if ( is_array( $res ) ) {
 581                                 foreach ( $res as $i => $size ) {
 582                                         $sizes[$types[$i]] = $size;
 583                                 }
 584                         }
 585                 } catch ( RedisException $e ) {
 586                         $this->throwRedisException( $this->server, $conn, $e );
 587                 }
 588
 589                 return $sizes;
 590         }
 591
 592         /**
 593          * This function should not be called outside JobQueueRedis
 594          *
 595          * @param $uid string
 596          * @param $conn RedisConnRef
 597          * @return Job|bool Returns false if the job does not exist
 598          * @throws MWException
 599          */
 600         public function getJobFromUidInternal( $uid, RedisConnRef $conn ) {
 601                 try {
 602                         $data = $conn->hGet( $this->getQueueKey( 'h-data' ), $uid );
 603                         if ( $data === false ) {
 604                                 return false; // not found
 605                         }
 606                         $item = $this->unserialize( $conn->hGet( $this->getQueueKey( 'h-data' ), $uid ) );
 607                         if ( !is_array( $item ) ) { // this shouldn't happen
 608                                 throw new MWException( "Could not find job with ID '$uid'." );
 609                         }
 610                         $title = Title::makeTitle( $item['namespace'], $item['title'] );
 611                         $job = Job::factory( $item['type'], $title, $item['params'] );
 612                         $job->metadata['uuid'] = $item['uuid'];
 613
 614                         return $job;
 615                 } catch ( RedisException $e ) {
 616                         $this->throwRedisException( $this->server, $conn, $e );
 617                 }
 618         }
 619
 620         /**
 621          * Release any ready delayed jobs into the queue
 622          *
 623          * @return integer Number of jobs released
 624          * @throws MWException
 625          */
 626         public function releaseReadyDelayedJobs() {
 627                 $count = 0;
 628
 629                 $conn = $this->getConnection();
 630                 try {
 631                         static $script =
 632 <<<LUA
 633                         -- Get the list of ready delayed jobs, sorted by readiness
 634                         local ids = redis.call('zRangeByScore',KEYS[1],0,ARGV[1])
 635                         -- Migrate the jobs from the "delayed" set to the "unclaimed" list
 636                         for k,id in ipairs(ids) do
 637                                 redis.call('lPush',KEYS[2],id)
 638                                 redis.call('zRem',KEYS[1],id)
 639                         end
 640                         return #ids
 641 LUA;
 642                         $count += (int)$conn->luaEval( $script,
 643                                 array(
 644                                         $this->getQueueKey( 'z-delayed' ), // KEYS[1]
 645                                         $this->getQueueKey( 'l-unclaimed' ), // KEYS[2]
 646                                         time() // ARGV[1]; max "delay until" UNIX timestamp
 647                                 ),
 648                                 2 # first two arguments are keys
 649                         );
 650                 } catch ( RedisException $e ) {
 651                         $this->throwRedisException( $this->server, $conn, $e );
 652                 }
 653
 654                 return $count;
 655         }
 656
 657         /**
 658          * Recycle or destroy any jobs that have been claimed for too long
 659          *
 660          * @return integer Number of jobs recycled/deleted
 661          * @throws MWException
 662          */
 663         public function recycleAndDeleteStaleJobs() {
 664                 if ( $this->claimTTL <= 0 ) { // sanity
 665                         throw new MWException( "Cannot recycle jobs since acknowledgements are disabled." );
 666                 }
 667                 $count = 0;
 668                 // For each job item that can be retried, we need to add it back to the
 669                 // main queue and remove it from the list of currenty claimed job items.
 670                 // For those that cannot, they are marked as dead and kept around for
 671                 // investigation and manual job restoration but are eventually deleted.
 672                 $conn = $this->getConnection();
 673                 try {
 674                         $now = time();
 675                         static $script =
 676 <<<LUA
 677                         local released,abandoned,pruned = 0,0,0
 678                         -- Get all non-dead jobs that have an expired claim on them.
 679                         -- The score for each item is the last claim timestamp (UNIX).
 680                         local staleClaims = redis.call('zRangeByScore',KEYS[1],0,ARGV[1])
 681                         for k,id in ipairs(staleClaims) do
 682                                 local timestamp = redis.call('zScore',KEYS[1],id)
 683                                 local attempts = redis.call('hGet',KEYS[2],id)
 684                                 if attempts < ARGV[3] then
 685                                         -- Claim expired and retries left: re-enqueue the job
 686                                         redis.call('lPush',KEYS[3],id)
 687                                         redis.call('hIncrBy',KEYS[2],id,1)
 688                                         released = released + 1
 689                                 else
 690                                         -- Claim expired and no retries left: mark the job as dead
 691                                         redis.call('zAdd',KEYS[5],timestamp,id)
 692                                         abandoned = abandoned + 1
 693                                 end
 694                                 redis.call('zRem',KEYS[1],id)
 695                         end
 696                         -- Get all of the dead jobs that have been marked as dead for too long.
 697                         -- The score for each item is the last claim timestamp (UNIX).
 698                         local deadClaims = redis.call('zRangeByScore',KEYS[5],0,ARGV[2])
 699                         for k,id in ipairs(deadClaims) do
 700                                 -- Stale and out of retries: remove any traces of the job
 701                                 redis.call('zRem',KEYS[5],id)
 702                                 redis.call('hDel',KEYS[2],id)
 703                                 redis.call('hDel',KEYS[4],id)
 704                                 pruned = pruned + 1
 705                         end
 706                         return {released,abandoned,pruned}
 707 LUA;
 708                         $res = $conn->luaEval( $script,
 709                                 array(
 710                                         $this->getQueueKey( 'z-claimed' ), # KEYS[1]
 711                                         $this->getQueueKey( 'h-attempts' ), # KEYS[2]
 712                                         $this->getQueueKey( 'l-unclaimed' ), # KEYS[3]
 713                                         $this->getQueueKey( 'h-data' ), # KEYS[4]
 714                                         $this->getQueueKey( 'z-abandoned' ), # KEYS[5]
 715                                         $now - $this->claimTTL, # ARGV[1]
 716                                         $now - self::MAX_AGE_PRUNE, # ARGV[2]
 717                                         $this->maxTries # ARGV[3]
 718                                 ),
 719                                 5 # number of first argument(s) that are keys
 720                         );
 721                         if ( $res ) {
 722                                 list( $released, $abandoned, $pruned ) = $res;
 723                                 $count += $released + $pruned;
 724                                 JobQueue::incrStats( 'job-recycle', $this->type, $released );
 725                                 JobQueue::incrStats( 'job-abandon', $this->type, $abandoned );
 726                         }
 727                 } catch ( RedisException $e ) {
 728                         $this->throwRedisException( $this->server, $conn, $e );
 729                 }
 730
 731                 return $count;
 732         }
 733
 734         /**
 735          * @return Array
 736          */
 737         protected function doGetPeriodicTasks() {
 738                 $tasks = array();
 739                 if ( $this->claimTTL > 0 ) {
 740                         $tasks['recycleAndDeleteStaleJobs'] = array(
 741                                 'callback' => array( $this, 'recycleAndDeleteStaleJobs' ),
 742                                 'period' => ceil( $this->claimTTL / 2 )
 743                         );
 744                 }
 745                 if ( $this->checkDelay ) {
 746                         $tasks['releaseReadyDelayedJobs'] = array(
 747                                 'callback' => array( $this, 'releaseReadyDelayedJobs' ),
 748                                 'period' => 300 // 5 minutes
 749                         );
 750                 }
 751
 752                 return $tasks;
 753         }
 754
 755         /**
 756          * @param $job Job
 757          * @return array
 758          */
 759         protected function getNewJobFields( Job $job ) {
 760                 return array(
 761                         // Fields that describe the nature of the job
 762                         'type' => $job->getType(),
 763                         'namespace' => $job->getTitle()->getNamespace(),
 764                         'title' => $job->getTitle()->getDBkey(),
 765                         'params' => $job->getParams(),
 766                         // Some jobs cannot run until a "release timestamp"
 767                         'rtimestamp' => $job->getReleaseTimestamp() ? : 0,
 768                         // Additional job metadata
 769                         'uuid' => UIDGenerator::newRawUUIDv4( UIDGenerator::QUICK_RAND ),
 770                         'sha1' => $job->ignoreDuplicates()
 771                                         ? wfBaseConvert( sha1( serialize( $job->getDeduplicationInfo() ) ), 16, 36, 31 )
 772                                         : '',
 773                         'timestamp' => time() // UNIX timestamp
 774                 );
 775         }
 776
 777         /**
 778          * @param $fields array
 779          * @return Job|bool
 780          */
 781         protected function getJobFromFields( array $fields ) {
 782                 $title = Title::makeTitleSafe( $fields['namespace'], $fields['title'] );
 783                 if ( $title ) {
 784                         $job = Job::factory( $fields['type'], $title, $fields['params'] );
 785                         $job->metadata['uuid'] = $fields['uuid'];
 786
 787                         return $job;
 788                 }
 789
 790                 return false;
 791         }
 792
 793         /**
 794          * @param array $fields
 795          * @return string Serialized and possibly compressed version of $fields
 796          */
 797         protected function serialize( array $fields ) {
 798                 $blob = serialize( $fields );
 799                 if ( $this->compression === 'gzip'
 800                         && strlen( $blob ) >= 1024
 801                         && function_exists( 'gzdeflate' )
 802                 ) {
 803                         $object = (object)array( 'blob' => gzdeflate( $blob ), 'enc' => 'gzip' );
 804                         $blobz = serialize( $object );
 805
 806                         return ( strlen( $blobz ) < strlen( $blob ) ) ? $blobz : $blob;
 807                 } else {
 808                         return $blob;
 809                 }
 810         }
 811
 812         /**
 813          * @param string $blob
 814          * @return array|bool Unserialized version of $blob or false
 815          */
 816         protected function unserialize( $blob ) {
 817                 $fields = unserialize( $blob );
 818                 if ( is_object( $fields ) ) {
 819                         if ( $fields->enc === 'gzip' && function_exists( 'gzinflate' ) ) {
 820                                 $fields = unserialize( gzinflate( $fields->blob ) );
 821                         } else {
 822                                 $fields = false;
 823                         }
 824                 }
 825
 826                 return is_array( $fields ) ? $fields : false;
 827         }
 828
 829         /**
 830          * Get a connection to the server that handles all sub-queues for this queue
 831          *
 832          * @return Array (server name, Redis instance)
 833          * @throws MWException
 834          */
 835         protected function getConnection() {
 836                 $conn = $this->redisPool->getConnection( $this->server );
 837                 if ( !$conn ) {
 838                         throw new JobQueueConnectionError( "Unable to connect to redis server." );
 839                 }
 840
 841                 return $conn;
 842         }
 843
 844         /**
 845          * @param $server string
 846          * @param $conn RedisConnRef
 847          * @param $e RedisException
 848          * @throws MWException
 849          */
 850         protected function throwRedisException( $server, RedisConnRef $conn, $e ) {
 851                 $this->redisPool->handleException( $server, $conn, $e );
 852                 throw new JobQueueError( "Redis server error: {$e->getMessage()}\n" );
 853         }
 854
 855         /**
 856          * @param $prop string
 857          * @param $type string|null
 858          * @return string
 859          */
 860         private function getQueueKey( $prop, $type = null ) {
 861                 $type = is_string( $type ) ? $type : $this->type;
 862                 list( $db, $prefix ) = wfSplitWikiID( $this->wiki );
 863                 if ( strlen( $this->key ) ) { // namespaced queue (for testing)
 864                         return wfForeignMemcKey( $db, $prefix, 'jobqueue', $type, $this->key, $prop );
 865                 } else {
 866                         return wfForeignMemcKey( $db, $prefix, 'jobqueue', $type, $prop );
 867                 }
 868         }
 869
 870         /**
 871          * @param $key string
 872          * @return void
 873          */
 874         public function setTestingPrefix( $key ) {
 875                 $this->key = $key;
 876         }
 877 }