includes/job/JobQueue.php

   1 <?php
   2 /**
   3  * Job queue base 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  * @defgroup JobQueue JobQueue
  22  * @author Aaron Schulz
  23  */
  24
  25 /**
  26  * Class to handle enqueueing and running of background jobs
  27  *
  28  * @ingroup JobQueue
  29  * @since 1.20
  30  */
  31 abstract class JobQueue {
  32         protected $wiki; // string; wiki ID
  33         protected $type; // string; job type
  34         protected $order; // string; job priority for pop()
  35
  36         const QoS_Atomic = 1; // integer; "all-or-nothing" job insertions
  37
  38         /**
  39          * @param $params array
  40          */
  41         protected function __construct( array $params ) {
  42                 $this->wiki  = $params['wiki'];
  43                 $this->type  = $params['type'];
  44                 $this->order = isset( $params['order'] ) ? $params['order'] : 'random';
  45         }
  46
  47         /**
  48          * Get a job queue object of the specified type.
  49          * $params includes:
  50          *     class : what job class to use (determines job type)
  51          *     wiki  : wiki ID of the wiki the jobs are for (defaults to current wiki)
  52          *     type  : The name of the job types this queue handles
  53          *     order : Order that pop() selects jobs, either "timestamp" or "random".
  54          *             If "timestamp" is used, the queue will effectively be FIFO. Note that
  55          *             pop() will not be exactly FIFO, and even if it was, job completion would
  56          *             not appear to be exactly FIFO since jobs can take different times to finish.
  57          *             If "random" is used, pop() will pick jobs in random order. This might be
  58          *             useful for improving concurrency depending on the queue storage medium.
  59          *
  60          * @param $params array
  61          * @return JobQueue
  62          * @throws MWException
  63          */
  64         final public static function factory( array $params ) {
  65                 $class = $params['class'];
  66                 if ( !MWInit::classExists( $class ) ) {
  67                         throw new MWException( "Invalid job queue class '$class'." );
  68                 }
  69                 $obj = new $class( $params );
  70                 if ( !( $obj instanceof self ) ) {
  71                         throw new MWException( "Class '$class' is not a " . __CLASS__ . " class." );
  72                 }
  73                 return $obj;
  74         }
  75
  76         /**
  77          * @return string Wiki ID
  78          */
  79         final public function getWiki() {
  80                 return $this->wiki;
  81         }
  82
  83         /**
  84          * @return string Job type that this queue handles
  85          */
  86         final public function getType() {
  87                 return $this->type;
  88         }
  89
  90         /**
  91          * @return bool Quickly check if the queue is empty
  92          */
  93         final public function isEmpty() {
  94                 wfProfileIn( __METHOD__ );
  95                 $res = $this->doIsEmpty();
  96                 wfProfileOut( __METHOD__ );
  97                 return $res;
  98         }
  99
 100         /**
 101          * @see JobQueue::isEmpty()
 102          * @return bool
 103          */
 104         abstract protected function doIsEmpty();
 105
 106         /**
 107          * Push a batch of jobs into the queue
 108          *
 109          * @param $jobs array List of Jobs
 110          * @param $flags integer Bitfield (supports JobQueue::QoS_Atomic)
 111          * @return bool
 112          */
 113         final public function batchPush( array $jobs, $flags = 0 ) {
 114                 foreach ( $jobs as $job ) {
 115                         if ( $job->getType() !== $this->type ) {
 116                                 throw new MWException( "Got '{$job->getType()}' job; expected '{$this->type}'." );
 117                         }
 118                 }
 119                 wfProfileIn( __METHOD__ );
 120                 $ok = $this->doBatchPush( $jobs, $flags );
 121                 if ( $ok ) {
 122                         wfIncrStats( 'job-insert', count( $jobs ) );
 123                 }
 124                 wfProfileOut( __METHOD__ );
 125                 return $ok;
 126         }
 127
 128         /**
 129          * @see JobQueue::batchPush()
 130          * @return bool
 131          */
 132         abstract protected function doBatchPush( array $jobs, $flags );
 133
 134         /**
 135          * Pop a job off of the queue
 136          *
 137          * @return Job|bool Returns false on failure
 138          */
 139         final public function pop() {
 140                 wfProfileIn( __METHOD__ );
 141                 $job = $this->doPop();
 142                 if ( $job ) {
 143                         wfIncrStats( 'job-pop' );
 144                 }
 145                 wfProfileOut( __METHOD__ );
 146                 return $job;
 147         }
 148
 149         /**
 150          * @see JobQueue::pop()
 151          * @return Job
 152          */
 153         abstract protected function doPop();
 154
 155         /**
 156          * Acknowledge that a job was completed
 157          *
 158          * @param $job Job
 159          * @return bool
 160          */
 161         final public function ack( Job $job ) {
 162                 if ( $job->getType() !== $this->type ) {
 163                         throw new MWException( "Got '{$job->getType()}' job; expected '{$this->type}'." );
 164                 }
 165                 wfProfileIn( __METHOD__ );
 166                 $ok = $this->doAck( $job );
 167                 wfProfileOut( __METHOD__ );
 168                 return $ok;
 169         }
 170
 171         /**
 172          * @see JobQueue::ack()
 173          * @return bool
 174          */
 175         abstract protected function doAck( Job $job );
 176
 177         /**
 178          * Wait for any slaves or backup servers to catch up
 179          *
 180          * @return void
 181          */
 182         final public function waitForBackups() {
 183                 wfProfileIn( __METHOD__ );
 184                 $this->doWaitForBackups();
 185                 wfProfileOut( __METHOD__ );
 186         }
 187
 188         /**
 189          * @see JobQueue::waitForBackups()
 190          * @return void
 191          */
 192         protected function doWaitForBackups() {}
 193 }