includes/jobqueue/utils/BacklinkJobUtils.php

   1 <?php
   2 /**
   3  * Job to update links for a given title.
   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  * @ingroup JobQueue
  22  * @author Aaron Schulz
  23  */
  24
  25 /**
  26  * Class with Backlink related Job helper methods
  27  *
  28  * @ingroup JobQueue
  29  * @since 1.23
  30  */
  31 class BacklinkJobUtils {
  32         /**
  33          * Break down $job into approximately ($bSize/$cSize) leaf jobs and a single partition
  34          * job that covers the remaining backlink range (if needed). Jobs for the first $bSize
  35          * titles are collated ($cSize per job) into leaf jobs to do actual work. All the
  36          * resulting jobs are of the same class as $job. No partition job is returned if the
  37          * range covered by $job was less than $bSize, as the leaf jobs have full coverage.
  38          *
  39          * The leaf jobs have the 'pages' param set to a (<page ID>:(<namespace>,<DB key>),...)
  40          * map so that the run() function knows what pages to act on. The leaf jobs will keep
  41          * the same job title as the parent job (e.g. $job).
  42          *
  43          * The partition jobs have the 'range' parameter set to a map of the format
  44          * (start:<integer>, end:<integer>, batchSize:<integer>, subranges:((<start>,<end>),...)),
  45          * the 'table' parameter set to that of $job, and the 'recursive' parameter set to true.
  46          * This method can be called on the resulting job to repeat the process again.
  47          *
  48          * The job provided ($job) must have the 'recursive' parameter set to true and the 'table'
  49          * parameter must be set to a backlink table. The job title will be used as the title to
  50          * find backlinks for. Any 'range' parameter must follow the same format as mentioned above.
  51          * This should be managed by recursive calls to this method.
  52          *
  53          * The first jobs return are always the leaf jobs. This lets the caller use push() to
  54          * put them directly into the queue and works well if the queue is FIFO. In such a queue,
  55          * the leaf jobs have to get finished first before anything can resolve the next partition
  56          * job, which keeps the queue very small.
  57          *
  58          * $opts includes:
  59          *   - params : extra job parameters to include in each job
  60          *
  61          * @param Job $job
  62          * @param int $bSize BacklinkCache partition size; usually $wgUpdateRowsPerJob
  63          * @param int $cSize Max titles per leaf job; Usually 1 or a modest value
  64          * @param array $opts Optional parameter map
  65          * @return Job[] List of Job objects
  66          */
  67         public static function partitionBacklinkJob( Job $job, $bSize, $cSize, $opts = array() ) {
  68                 $class = get_class( $job );
  69                 $title = $job->getTitle();
  70                 $params = $job->getParams();
  71
  72                 if ( isset( $params['pages'] ) || empty( $params['recursive'] ) ) {
  73                         $ranges = array(); // sanity; this is a leaf node
  74                         wfWarn( __METHOD__ . " called on {$job->getType()} leaf job (explosive recursion)." );
  75                 } elseif ( isset( $params['range'] ) ) {
  76                         // This is a range job to trigger the insertion of partitioned/title jobs...
  77                         $ranges = $params['range']['subranges'];
  78                         $realBSize = $params['range']['batchSize'];
  79                 } else {
  80                         // This is a base job to trigger the insertion of partitioned jobs...
  81                         $ranges = $title->getBacklinkCache()->partition( $params['table'], $bSize );
  82                         $realBSize = $bSize;
  83                 }
  84
  85                 $extraParams = isset( $opts['params'] ) ? $opts['params'] : array();
  86
  87                 $jobs = array();
  88                 // Combine the first range (of size $bSize) backlinks into leaf jobs
  89                 if ( isset( $ranges[0] ) ) {
  90                         list( $start, $end ) = $ranges[0];
  91                         $titles = $title->getBacklinkCache()->getLinks( $params['table'], $start, $end );
  92                         foreach ( array_chunk( iterator_to_array( $titles ), $cSize ) as $titleBatch ) {
  93                                 $pages = array();
  94                                 foreach ( $titleBatch as $tl ) {
  95                                         $pages[$tl->getArticleId()] = array( $tl->getNamespace(), $tl->getDBKey() );
  96                                 }
  97                                 $jobs[] = new $class(
  98                                         $title, // maintain parent job title
  99                                         array( 'pages' => $pages ) + $extraParams
 100                                 );
 101                         }
 102                 }
 103                 // Take all of the remaining ranges and build a partition job from it
 104                 if ( isset( $ranges[1] ) ) {
 105                         $jobs[] = new $class(
 106                                 $title, // maintain parent job title
 107                                 array(
 108                                         'recursive'     => true,
 109                                         'table'         => $params['table'],
 110                                         'range'         => array(
 111                                                 'start'     => $ranges[1][0],
 112                                                 'end'       => $ranges[count( $ranges ) - 1][1],
 113                                                 'batchSize' => $realBSize,
 114                                                 'subranges' => array_slice( $ranges, 1 )
 115                                         ),
 116                                 ) + $extraParams
 117                         );
 118                 }
 119
 120                 return $jobs;
 121         }
 122 }