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  * @ingroup JobQueue
  28  * @since 1.21
  29  */
  30 class JobQueueRedis extends JobQueue {
  31         /** @var RedisConnectionPool */
  32         protected $redisPool;
  33
  34         protected $server; // string; server address
  35
  36         const ROOTJOB_TTL   = 1209600; // integer; seconds to remember root jobs (14 days)
  37         const MAX_AGE_PRUNE = 604800; // integer; seconds a job can live once claimed (7 days)
  38
  39         protected $key; // string; key to prefix the queue keys with (used for testing)
  40
  41         /**
  42          * @params include:
  43          *   - redisConfig : An array of parameters to RedisConnectionPool::__construct().
  44          *   - redisServer : A hostname/port combination or the absolute path of a UNIX socket.
  45          *                   If a hostname is specified but no port, the standard port number
  46          *                   6379 will be used. Required.
  47          * @param array $params
  48          */
  49         public function __construct( array $params ) {
  50                 parent::__construct( $params );
  51                 $this->server = $params['redisServer'];
  52                 $this->redisPool = RedisConnectionPool::singleton( $params['redisConfig'] );
  53         }
  54
  55         /**
  56          * @see JobQueue::doIsEmpty()
  57          * @return bool
  58          * @throws MWException
  59          */
  60         protected function doIsEmpty() {
  61                 $conn = $this->getConnection();
  62                 try {
  63                         return ( $conn->lSize( $this->getQueueKey( 'l-unclaimed' ) ) == 0 );
  64                 } catch ( RedisException $e ) {
  65                         $this->throwRedisException( $this->server, $conn, $e );
  66                 }
  67         }
  68
  69         /**
  70          * @see JobQueue::doGetSize()
  71          * @return integer
  72          * @throws MWException
  73          */
  74         protected function doGetSize() {
  75                 $conn = $this->getConnection();
  76                 try {
  77                         return $conn->lSize( $this->getQueueKey( 'l-unclaimed' ) );
  78                 } catch ( RedisException $e ) {
  79                         $this->throwRedisException( $this->server, $conn, $e );
  80                 }
  81         }
  82
  83         /**
  84          * @see JobQueue::doGetAcquiredCount()
  85          * @return integer
  86          * @throws MWException
  87          */
  88         protected function doGetAcquiredCount() {
  89                 if ( $this->claimTTL <= 0 ) {
  90                         return 0; // no acknowledgements
  91                 }
  92                 $conn = $this->getConnection();
  93                 try {
  94                         return $conn->lSize( $this->getQueueKey( 'l-claimed' ) );
  95                 } catch ( RedisException $e ) {
  96                         $this->throwRedisException( $this->server, $conn, $e );
  97                 }
  98         }
  99
 100         /**
 101          * @see JobQueue::doBatchPush()
 102          * @param array $jobs
 103          * @param $flags
 104          * @return bool
 105          * @throws MWException
 106          */
 107         protected function doBatchPush( array $jobs, $flags ) {
 108                 if ( !count( $jobs ) ) {
 109                         return true;
 110                 }
 111
 112                 // Convert the jobs into a list of field maps
 113                 $items = array(); // (uid => job fields map)
 114                 foreach ( $jobs as $job ) {
 115                         $item = $this->getNewJobFields( $job );
 116                         $items[$item['uid']] = $item;
 117                 }
 118
 119                 $dedupUids = array(); // list of uids to check for duplicates
 120                 foreach ( $items as $item ) {
 121                         if ( $this->isHashUid( $item['uid'] ) ) { // hash identifier => de-duplicate
 122                                 $dedupUids[] = $item['uid'];
 123                         }
 124                 }
 125
 126                 $conn = $this->getConnection();
 127                 try {
 128                         // Find which of these jobs are duplicates of unclaimed jobs in the queue...
 129                         if ( count( $dedupUids ) ) {
 130                                 $conn->multi( Redis::PIPELINE );
 131                                 foreach ( $dedupUids as $uid ) { // check if job data exists
 132                                         $conn->exists( $this->prefixWithQueueKey( 'data', $uid ) );
 133                                 }
 134                                 if ( $this->claimTTL > 0 ) { // check which jobs were claimed
 135                                         foreach ( $dedupUids as $uid ) {
 136                                                 $conn->hExists( $this->prefixWithQueueKey( 'h-meta', $uid ), 'ctime' );
 137                                         }
 138                                         list( $exists, $claimed ) = array_chunk( $conn->exec(), count( $dedupUids ) );
 139                                 } else {
 140                                         $exists = $conn->exec();
 141                                         $claimed = array(); // no claim system
 142                                 }
 143                                 // Remove the duplicate jobs to cut down on pushing duplicate uids...
 144                                 foreach ( $dedupUids as $k => $uid ) {
 145                                         if ( $exists[$k] && empty( $claimed[$k] ) ) {
 146                                                 unset( $items[$uid] );
 147                                         }
 148                                 }
 149                         }
 150                         // Actually push the non-duplicate jobs into the queue...
 151                         if ( count( $items ) ) {
 152                                 $uids = array_keys( $items );
 153                                 $conn->multi( Redis::MULTI ); // begin (atomic trx)
 154                                 $conn->mSet( $this->prefixKeysWithQueueKey( 'data', $items ) );
 155                                 call_user_func_array(
 156                                         array( $conn, 'lPush' ),
 157                                         array_merge( array( $this->getQueueKey( 'l-unclaimed' ) ), $uids )
 158                                 );
 159                                 $res = $conn->exec(); // commit (atomic trx)
 160                                 if ( in_array( false, $res, true ) ) {
 161                                         wfDebugLog( 'JobQueueRedis', "Could not insert {$this->type} job(s)." );
 162                                         return false;
 163                                 }
 164                         }
 165                         wfIncrStats( 'job-insert', count( $items ) );
 166                         wfIncrStats( 'job-insert-duplicate', count( $jobs ) - count( $items ) );
 167                 } catch ( RedisException $e ) {
 168                         $this->throwRedisException( $this->server, $conn, $e );
 169                 }
 170
 171                 return true;
 172         }
 173
 174         /**
 175          * @see JobQueue::doPop()
 176          * @return Job|bool
 177          * @throws MWException
 178          */
 179         protected function doPop() {
 180                 $job = false;
 181
 182                 if ( $this->claimTTL <= 0 && mt_rand( 0, 99 ) == 0 ) {
 183                         $this->cleanupClaimedJobs(); // prune jobs and IDs from the "garbage" list
 184                 }
 185
 186                 $conn = $this->getConnection();
 187                 try {
 188                         do {
 189                                 // Atomically pop an item off the queue and onto the "claimed" list
 190                                 $uid = $conn->rpoplpush(
 191                                         $this->getQueueKey( 'l-unclaimed' ),
 192                                         $this->getQueueKey( 'l-claimed' )
 193                                 );
 194                                 if ( $uid === false ) {
 195                                         break; // no jobs; nothing to do
 196                                 }
 197
 198                                 wfIncrStats( 'job-pop' );
 199                                 $conn->multi( Redis::PIPELINE );
 200                                 $conn->get( $this->prefixWithQueueKey( 'data', $uid ) );
 201                                 if ( $this->claimTTL > 0 ) {
 202                                         // Set the claim timestamp metadata. If this step fails, then
 203                                         // the timestamp will be assumed to be the current timestamp by
 204                                         // recycleAndDeleteStaleJobs() as of the next time that it runs.
 205                                         // If two runners claim duplicate jobs, one will abort here.
 206                                         $conn->hSetNx( $this->prefixWithQueueKey( 'h-meta', $uid ), 'ctime', time() );
 207                                 } else {
 208                                         // If this fails, the message key will be deleted in cleanupClaimedJobs().
 209                                         // If two runners claim duplicate jobs, one of them will abort here.
 210                                         $conn->delete(
 211                                                 $this->prefixWithQueueKey( 'h-meta', $uid ),
 212                                                 $this->prefixWithQueueKey( 'data', $uid ) );
 213                                 }
 214                                 list( $item, $ok ) = $conn->exec();
 215                                 if ( $item === false || ( $this->claimTTL && !$ok ) ) {
 216                                         wfDebug( "Could not find or delete job $uid; probably was a duplicate." );
 217                                         continue; // job was probably a duplicate
 218                                 }
 219
 220                                 // If $item is invalid, recycleAndDeleteStaleJobs() will cleanup as needed
 221                                 $job = $this->getJobFromFields( $item ); // may be false
 222                         } while ( !$job ); // job may be false if invalid
 223                 } catch ( RedisException $e ) {
 224                         $this->throwRedisException( $this->server, $conn, $e );
 225                 }
 226
 227                 // Flag this job as an old duplicate based on its "root" job...
 228                 try {
 229                         if ( $job && $this->isRootJobOldDuplicate( $job ) ) {
 230                                 wfIncrStats( 'job-pop-duplicate' );
 231                                 return DuplicateJob::newFromJob( $job ); // convert to a no-op
 232                         }
 233                 } catch ( MWException $e ) {} // don't lose jobs over this
 234
 235                 return $job;
 236         }
 237
 238         /**
 239          * @see JobQueue::doAck()
 240          * @param Job $job
 241          * @return Job|bool
 242          * @throws MWException
 243          */
 244         protected function doAck( Job $job ) {
 245                 if ( $this->claimTTL > 0 ) {
 246                         $conn = $this->getConnection();
 247                         try {
 248                                 // Get the exact field map this Job came from, regardless of whether
 249                                 // the job was transformed into a DuplicateJob or anything of the sort.
 250                                 $item = $job->metadata['sourceFields'];
 251
 252                                 $conn->multi( Redis::MULTI ); // begin (atomic trx)
 253                                 // Remove the first instance of this job scanning right-to-left.
 254                                 // This is O(N) in the worst case, but is likely to be much faster since
 255                                 // jobs are pushed to the left and we are starting from the right, where
 256                                 // the longest running jobs are likely to be. These should be the first
 257                                 // jobs to be acknowledged assuming that job run times are roughly equal.
 258                                 $conn->lRem( $this->getQueueKey( 'l-claimed' ), $item['uid'], -1 );
 259                                 // Delete the job data and its claim metadata
 260                                 $conn->delete(
 261                                         $this->prefixWithQueueKey( 'h-meta', $item['uid'] ),
 262                                         $this->prefixWithQueueKey( 'data', $item['uid'] ) );
 263                                 $res = $conn->exec(); // commit (atomic trx)
 264
 265                                 if ( in_array( false, $res, true ) ) {
 266                                         wfDebugLog( 'JobQueueRedis', "Could not acknowledge {$this->type} job." );
 267                                         return false;
 268                                 }
 269                         } catch ( RedisException $e ) {
 270                                 $this->throwRedisException( $this->server, $conn, $e );
 271                         }
 272                 }
 273                 return true;
 274         }
 275
 276         /**
 277          * @see JobQueue::doDeduplicateRootJob()
 278          * @param Job $job
 279          * @return bool
 280          * @throws MWException
 281          */
 282         protected function doDeduplicateRootJob( Job $job ) {
 283                 $params = $job->getParams();
 284                 if ( !isset( $params['rootJobSignature'] ) ) {
 285                         throw new MWException( "Cannot register root job; missing 'rootJobSignature'." );
 286                 } elseif ( !isset( $params['rootJobTimestamp'] ) ) {
 287                         throw new MWException( "Cannot register root job; missing 'rootJobTimestamp'." );
 288                 }
 289                 $key = $this->getRootJobKey( $params['rootJobSignature'] );
 290
 291                 $conn = $this->getConnection();
 292                 try {
 293                         $timestamp = $conn->get( $key ); // current last timestamp of this job
 294                         if ( $timestamp && $timestamp >= $params['rootJobTimestamp'] ) {
 295                                 return true; // a newer version of this root job was enqueued
 296                         }
 297                         // Update the timestamp of the last root job started at the location...
 298                         return $conn->set( $key, $params['rootJobTimestamp'], self::ROOTJOB_TTL ); // 2 weeks
 299                 } catch ( RedisException $e ) {
 300                         $this->throwRedisException( $this->server, $conn, $e );
 301                 }
 302         }
 303
 304         /**
 305          * Check if the "root" job of a given job has been superseded by a newer one
 306          *
 307          * @param $job Job
 308          * @return bool
 309          * @throws MWException
 310          */
 311         protected function isRootJobOldDuplicate( Job $job ) {
 312                 $params = $job->getParams();
 313                 if ( !isset( $params['rootJobSignature'] ) ) {
 314                         return false; // job has no de-deplication info
 315                 } elseif ( !isset( $params['rootJobTimestamp'] ) ) {
 316                         wfDebugLog( 'JobQueueRedis', "Cannot check root job; missing 'rootJobTimestamp'." );
 317                         return false;
 318                 }
 319
 320                 $conn = $this->getConnection();
 321                 try {
 322                         // Get the last time this root job was enqueued
 323                         $timestamp = $conn->get( $this->getRootJobKey( $params['rootJobSignature'] ) );
 324                 } catch ( RedisException $e ) {
 325                         $this->throwRedisException( $this->server, $conn, $e );
 326                 }
 327
 328                 // Check if a new root job was started at the location after this one's...
 329                 return ( $timestamp && $timestamp > $params['rootJobTimestamp'] );
 330         }
 331
 332         /**
 333          * Recycle or destroy any jobs that have been claimed for too long
 334          *
 335          * @return integer Number of jobs recycled/deleted
 336          * @throws MWException
 337          */
 338         public function recycleAndDeleteStaleJobs() {
 339                 if ( $this->claimTTL <= 0 ) { // sanity
 340                         throw new MWException( "Cannot recycle jobs since acknowledgements are disabled." );
 341                 }
 342                 $count = 0;
 343                 // For each job item that can be retried, we need to add it back to the
 344                 // main queue and remove it from the list of currenty claimed job items.
 345                 $conn = $this->getConnection();
 346                 try {
 347                         // Avoid duplicate insertions of items to be re-enqueued
 348                         $conn->multi( Redis::MULTI );
 349                         $conn->setnx( $this->getQueueKey( 'lock' ), 1 );
 350                         $conn->expire( $this->getQueueKey( 'lock' ), 3600 );
 351                         if ( $conn->exec() !== array( true, true ) ) { // lock
 352                                 return $count; // already in progress
 353                         }
 354
 355                         $now = time();
 356                         $claimCutoff = $now - $this->claimTTL;
 357                         $pruneCutoff = $now - self::MAX_AGE_PRUNE;
 358
 359                         // Get the list of all claimed jobs
 360                         $claimedUids = $conn->lRange( $this->getQueueKey( 'l-claimed' ), 0, -1 );
 361                         // Get a map of (uid => claim metadata) for all claimed jobs
 362                         $metadata = $conn->mGet( $this->prefixValuesWithQueueKey( 'h-meta', $claimedUids ) );
 363
 364                         $uidsPush = array(); // items IDs to move to the "unclaimed" queue
 365                         $uidsRemove = array(); // item IDs to remove from "claimed" queue
 366                         foreach ( $claimedUids as $i => $uid ) { // all claimed items
 367                                 $info = $metadata[$i] ? $metadata[$i] : array();
 368                                 if ( isset( $info['ctime'] ) || isset( $info['rctime'] ) ) {
 369                                         // Prefer "ctime" (set by pop()) over "rctime" (set by this function)
 370                                         $ctime = isset( $info['ctime'] ) ? $info['ctime'] : $info['rctime'];
 371                                         // Claimed job claimed for too long?
 372                                         if ( $ctime < $claimCutoff ) {
 373                                                 // Get the number of failed attempts
 374                                                 $attempts = isset( $info['attempts'] ) ? $info['attempts'] : 0;
 375                                                 if ( $attempts < $this->maxTries ) {
 376                                                         $uidsPush[] = $uid; // retry it
 377                                                 } elseif ( $ctime < $pruneCutoff ) {
 378                                                         $uidsRemove[] = $uid; // just remove it
 379                                                 }
 380                                         }
 381                                 } else {
 382                                         // If pop() failed to set the claim timestamp, set it to the current time.
 383                                         // Since that function sets this non-atomically *after* moving the job to
 384                                         // the "claimed" queue, it may be the case that it just didn't set it yet.
 385                                         $conn->hSet( $this->prefixWithQueueKey( 'h-meta', $uid ), 'rctime', $now );
 386                                 }
 387                         }
 388
 389                         $conn->multi( Redis::MULTI ); // begin (atomic trx)
 390                         if ( count( $uidsPush ) ) { // move from "l-claimed" to "l-unclaimed"
 391                                 call_user_func_array(
 392                                         array( $conn, 'lPush' ),
 393                                         array_merge( array( $this->getQueueKey( 'l-unclaimed' ) ), $uidsPush )
 394                                 );
 395                                 foreach ( $uidsPush as $uid ) {
 396                                         $conn->lRem( $this->getQueueKey( 'l-claimed' ), $uid, -1 );
 397                                         $conn->hDel( $this->prefixWithQueueKey( 'h-meta', $uid ), 'ctime', 'rctime' );
 398                                         $conn->hIncrBy( $this->prefixWithQueueKey( 'h-meta', $uid ), 'attempts', 1 );
 399                                 }
 400                         }
 401                         foreach ( $uidsRemove as $uid ) { // remove from "l-claimed"
 402                                 $conn->lRem( $this->getQueueKey( 'l-claimed' ), $uid, -1 );
 403                                 $conn->delete( // delete job data and metadata
 404                                         $this->prefixWithQueueKey( 'h-meta', $uid ),
 405                                         $this->prefixWithQueueKey( 'data', $uid ) );
 406                         }
 407                         $res = $conn->exec(); // commit (atomic trx)
 408
 409                         if ( in_array( false, $res, true ) ) {
 410                                 wfDebugLog( 'JobQueueRedis', "Could not recycle {$this->type} job(s)." );
 411                         } else {
 412                                 $count += ( count( $uidsPush ) + count( $uidsRemove ) );
 413                                 wfIncrStats( 'job-recycle', count( $uidsPush ) );
 414                         }
 415
 416                         $conn->delete( $this->getQueueKey( 'lock' ) ); // unlock
 417                 } catch ( RedisException $e ) {
 418                         $this->throwRedisException( $this->server, $conn, $e );
 419                 }
 420
 421                 return $count;
 422         }
 423
 424         /**
 425          * Destroy any jobs that have been claimed
 426          *
 427          * @return integer Number of jobs deleted
 428          * @throws MWException
 429          */
 430         protected function cleanupClaimedJobs() {
 431                 $count = 0;
 432                 // Make sure the message for claimed jobs was deleted
 433                 // and remove the claimed job IDs from the "claimed" list.
 434                 $conn = $this->getConnection();
 435                 try {
 436                         // Avoid races and duplicate effort
 437                         $conn->multi( Redis::MULTI );
 438                         $conn->setnx( $this->getQueueKey( 'lock' ), 1 );
 439                         $conn->expire( $this->getQueueKey( 'lock' ), 3600 );
 440                         if ( $conn->exec() !== array( true, true ) ) { // lock
 441                                 return $count; // already in progress
 442                         }
 443                         // Get the list of all claimed jobs
 444                         $uids = $conn->lRange( $this->getQueueKey( 'l-claimed' ), 0, -1 );
 445                         if ( count( $uids ) ) {
 446                                 // Delete the message keys and delist the corresponding ids.
 447                                 // Since the only other changes to "l-claimed" are left pushes, we can just strip
 448                                 // off the elements read here using a right trim based on the number of ids read.
 449                                 $conn->multi( Redis::MULTI ); // begin (atomic trx)
 450                                 $conn->lTrim( $this->getQueueKey( 'l-claimed' ), 0, -count( $uids ) - 1 );
 451                                 $conn->delete( array_merge(
 452                                         $this->prefixValuesWithQueueKey( 'h-meta', $uids ),
 453                                         $this->prefixValuesWithQueueKey( 'data', $uids )
 454                                 ) );
 455                                 $res = $conn->exec(); // commit (atomic trx)
 456
 457                                 if ( in_array( false, $res, true ) ) {
 458                                         wfDebugLog( 'JobQueueRedis', "Could not purge {$this->type} job(s)." );
 459                                 } else {
 460                                         $count += count( $uids );
 461                                 }
 462                         }
 463                         $conn->delete( $this->getQueueKey( 'lock' ) ); // unlock
 464                 } catch ( RedisException $e ) {
 465                         $this->throwRedisException( $this->server, $conn, $e );
 466                 }
 467
 468                 return $count;
 469         }
 470
 471         /**
 472          * @return Array
 473          */
 474         protected function doGetPeriodicTasks() {
 475                 if ( $this->claimTTL > 0 ) {
 476                         return array(
 477                                 'recycleAndDeleteStaleJobs' => array(
 478                                         'callback' => array( $this, 'recycleAndDeleteStaleJobs' ),
 479                                         'period'   => ceil( $this->claimTTL / 2 )
 480                                 )
 481                         );
 482                 } else {
 483                         return array();
 484                 }
 485         }
 486
 487         /**
 488          * @param $job Job
 489          * @return array
 490          */
 491         protected function getNewJobFields( Job $job ) {
 492                 return array(
 493                         // Fields that describe the nature of the job
 494                         'type'      => $job->getType(),
 495                         'namespace' => $job->getTitle()->getNamespace(),
 496                         'title'     => $job->getTitle()->getDBkey(),
 497                         'params'    => $job->getParams(),
 498                         // Additional metadata
 499                         'uid'       => $job->ignoreDuplicates()
 500                                 ? wfBaseConvert( sha1( serialize( $job->getDeduplicationInfo() ) ), 16, 36, 31 )
 501                                 : wfRandomString( 32 ),
 502                         'timestamp' => time() // UNIX timestamp
 503                 );
 504         }
 505
 506         /**
 507          * @param $fields array
 508          * @return Job|bool
 509          */
 510         protected function getJobFromFields( array $fields ) {
 511                 $title = Title::makeTitleSafe( $fields['namespace'], $fields['title'] );
 512                 if ( $title ) {
 513                         $job = Job::factory( $fields['type'], $title, $fields['params'] );
 514                         $job->metadata['sourceFields'] = $fields;
 515                         return $job;
 516                 }
 517                 return false;
 518         }
 519
 520         /**
 521          * @param $uid string Job UID
 522          * @return bool Whether $uid is a SHA-1 hash based identifier for de-duplication
 523          */
 524         protected function isHashUid( $uid ) {
 525                 return strlen( $uid ) == 31;
 526         }
 527
 528         /**
 529          * Get a connection to the server that handles all sub-queues for this queue
 530          *
 531          * @return Array (server name, Redis instance)
 532          * @throws MWException
 533          */
 534         protected function getConnection() {
 535                 $conn = $this->redisPool->getConnection( $this->server );
 536                 if ( !$conn ) {
 537                         throw new MWException( "Unable to connect to redis server." );
 538                 }
 539                 return $conn;
 540         }
 541
 542         /**
 543          * @param $server string
 544          * @param $conn RedisConnRef
 545          * @param $e RedisException
 546          * @throws MWException
 547          */
 548         protected function throwRedisException( $server, RedisConnRef $conn, $e ) {
 549                 $this->redisPool->handleException( $server, $conn, $e );
 550                 throw new MWException( "Redis server error: {$e->getMessage()}\n" );
 551         }
 552
 553         /**
 554          * @param $prop string
 555          * @return string
 556          */
 557         private function getQueueKey( $prop ) {
 558                 list( $db, $prefix ) = wfSplitWikiID( $this->wiki );
 559                 if ( strlen( $this->key ) ) { // namespaced queue (for testing)
 560                         return wfForeignMemcKey( $db, $prefix, 'jobqueue', $this->type, $this->key, $prop );
 561                 } else {
 562                         return wfForeignMemcKey( $db, $prefix, 'jobqueue', $this->type, $prop );
 563                 }
 564         }
 565
 566         /**
 567          * @param string $signature Hash identifier of the root job
 568          * @return string
 569          */
 570         private function getRootJobKey( $signature ) {
 571                 list( $db, $prefix ) = wfSplitWikiID( $this->wiki );
 572                 return wfForeignMemcKey( $db, $prefix, 'jobqueue', $this->type, 'rootjob', $signature );
 573         }
 574
 575         /**
 576          * @param $prop string
 577          * @param $string string
 578          * @return string
 579          */
 580         private function prefixWithQueueKey( $prop, $string ) {
 581                 return $this->getQueueKey( $prop ) . ':' . $string;
 582         }
 583
 584         /**
 585          * @param $prop string
 586          * @param $items array
 587          * @return Array
 588          */
 589         private function prefixValuesWithQueueKey( $prop, array $items ) {
 590                 $res = array();
 591                 foreach ( $items as $item ) {
 592                         $res[] = $this->prefixWithQueueKey( $prop, $item );
 593                 }
 594                 return $res;
 595         }
 596
 597         /**
 598          * @param $prop string
 599          * @param $items array
 600          * @return Array
 601          */
 602         private function prefixKeysWithQueueKey( $prop, array $items ) {
 603                 $res = array();
 604                 foreach ( $items as $key => $item ) {
 605                         $res[$this->prefixWithQueueKey( $prop, $key )] = $item;
 606                 }
 607                 return $res;
 608         }
 609
 610         /**
 611          * @param $key string
 612          * @return void
 613          */
 614         public function setTestingPrefix( $key ) {
 615                 $this->key = $key;
 616         }
 617 }