maintenance/nextJobDB.php

   1 <?php
   2 /**
   3  * Pick a database that has pending jobs
   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 Maintenance
  22  */
  23
  24 require_once( __DIR__ . '/Maintenance.php' );
  25
  26 /**
  27  * Maintenance script that picks a database that has pending jobs.
  28  *
  29  * @ingroup Maintenance
  30  */
  31 class nextJobDB extends Maintenance {
  32         public function __construct() {
  33                 parent::__construct();
  34                 $this->mDescription = "Pick a database that has pending jobs";
  35                 $this->addOption( 'type', "Search by job type", false, true );
  36                 $this->addOption( 'types', "Space separated list of job types to search for", false, true );
  37         }
  38
  39         public function execute() {
  40                 global $wgMemc;
  41
  42                 $type = false; // job type required/picked
  43                 if ( $this->hasOption( 'types' ) ) {
  44                         $types = explode( ' ', $this->getOption( 'types' ) );
  45                 } elseif ( $this->hasOption( 'type' ) ) {
  46                         $types = array( $this->getOption( 'type' ) );
  47                 } else {
  48                         $types = false;
  49                 }
  50
  51                 $memcKey = 'jobqueue:dbs:v3';
  52                 $pendingDbInfo = $wgMemc->get( $memcKey );
  53
  54                 // If the cache entry wasn't present, is stale, or in .1% of cases otherwise,
  55                 // regenerate the cache. Use any available stale cache if another process is
  56                 // currently regenerating the pending DB information.
  57                 if ( !is_array( $pendingDbInfo )
  58                         || ( time() - $pendingDbInfo['timestamp'] ) > 300 // 5 minutes
  59                         || mt_rand( 0, 999 ) == 0
  60                 ) {
  61                         if ( $wgMemc->add( "$memcKey:rebuild", 1, 1800 ) ) { // lock
  62                                 $pendingDbInfo = array(
  63                                         'pendingDBs' => $this->getPendingDbs(),
  64                                         'timestamp'  => time()
  65                                 );
  66                                 for ( $attempts=1; $attempts <= 25; ++$attempts ) {
  67                                         if ( $wgMemc->add( "$memcKey:lock", 1, 60 ) ) { // lock
  68                                                 $wgMemc->set( $memcKey, $pendingDbInfo );
  69                                                 $wgMemc->delete( "$memcKey:lock" ); // unlock
  70                                                 break;
  71                                         }
  72                                 }
  73                                 $wgMemc->delete( "$memcKey:rebuild" ); // unlock
  74                         }
  75                 }
  76
  77                 if ( !is_array( $pendingDbInfo ) || !$pendingDbInfo['pendingDBs'] ) {
  78                         return; // no DBs with jobs or cache is both empty and locked
  79                 }
  80
  81                 $pendingDBs = $pendingDbInfo['pendingDBs']; // convenience
  82                 do {
  83                         $again = false;
  84
  85                         if ( $types === false ) {
  86                                 $candidates = call_user_func_array( 'array_merge', $pendingDBs );
  87                         } else {
  88                                 $candidates = array();
  89                                 $possTypes = array_intersect( $types, array_keys( $pendingDBs ) );
  90                                 if ( $possTypes ) {
  91                                         $possTypes = array_values( $possTypes );
  92                                         $type = $possTypes[ mt_rand( 0, count( $possTypes ) - 1 ) ];
  93                                         $candidates = $pendingDBs[$type];
  94                                 }
  95                         }
  96                         if ( !$candidates ) {
  97                                 return; // no jobs for this type
  98                         }
  99
 100                         $candidates = array_values( $candidates );
 101                         $db = $candidates[ mt_rand( 0, count( $candidates ) - 1 ) ];
 102                         if ( !$this->checkJob( $type, $db ) ) {
 103                                 $pendingDBs = $this->delistDB( $pendingDBs, $db, $type );
 104                                 // Update the cache to remove the outdated information.
 105                                 // Make sure that this does not race (especially with full rebuilds).
 106                                 if ( $wgMemc->add( "$memcKey:lock", 1, 60 ) ) { // lock
 107                                         $curInfo = $wgMemc->get( $memcKey );
 108                                         if ( is_array( $curInfo ) ) {
 109                                                 $curInfo['pendingDBs'] =
 110                                                         $this->delistDB( $curInfo['pendingDBs'], $db, $type );
 111                                                 $wgMemc->set( $memcKey, $curInfo );
 112                                                 // May as well make use of this newer information
 113                                                 $pendingDBs = $curInfo['pendingDBs'];
 114                                         }
 115                                         $wgMemc->delete( "$memcKey:lock" ); // unlock
 116                                 }
 117                                 $again = true;
 118                         }
 119                 } while ( $again );
 120
 121                 if ( $this->hasOption( 'types' ) ) {
 122                         $this->output( $db . " " . $type . "\n" );
 123                 } else {
 124                         $this->output( $db . "\n" );
 125                 }
 126         }
 127
 128         private function delistDB( array $pendingDBs, $db, $type ) {
 129                 if ( $type === false ) {
 130                         // There are no jobs available in the current database
 131                         foreach ( $pendingDBs as $type2 => $dbs ) {
 132                                 $pendingDBs[$type2] = array_diff( $pendingDBs[$type2], array( $db ) );
 133                         }
 134                 } else {
 135                         // There are no jobs of this type available in the current database
 136                         $pendingDBs[$type] = array_diff( $pendingDBs[$type], array( $db ) );
 137                 }
 138                 return $pendingDBs;
 139         }
 140
 141         /**
 142          * Check if the specified database has a job of the specified type in it.
 143          * The type may be false to indicate "all".
 144          * @param $type string
 145          * @param $dbName string
 146          * @return bool
 147          */
 148         private function checkJob( $type, $dbName ) {
 149                 $group = JobQueueGroup::singleton( $dbName );
 150                 if ( $type === false ) {
 151                         foreach ( $group->getDefaultQueueTypes() as $type ) {
 152                                 if ( !$group->get( $type )->isEmpty() ) {
 153                                         return true;
 154                                 }
 155                         }
 156                         return false;
 157                 } else {
 158                         return !$group->get( $type )->isEmpty();
 159                 }
 160         }
 161
 162         /**
 163          * Get all databases that have a pending job
 164          * @return array
 165          */
 166         private function getPendingDbs() {
 167                 global $wgLocalDatabases;
 168
 169                 $pendingDBs = array(); // (job type => (db list))
 170                 foreach ( $wgLocalDatabases as $db ) {
 171                         $types = JobQueueGroup::singleton( $db )->getQueuesWithJobs();
 172                         foreach ( $types as $type ) {
 173                                 $pendingDBs[$type][] = $db;
 174                         }
 175                 }
 176
 177                 return $pendingDBs;
 178         }
 179 }
 180
 181 $maintClass = "nextJobDb";
 182 require_once( RUN_MAINTENANCE_IF_MAIN );