includes/objectcache/ObjectCache.php

   1 <?php
   2 /**
   3  * Functions to get cache objects.
   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 Cache
  22  */
  23
  24 /**
  25  * Functions to get cache objects
  26  *
  27  * @ingroup Cache
  28  */
  29 class ObjectCache {
  30         static $instances = array();
  31
  32         /**
  33          * Get a cached instance of the specified type of cache object.
  34          *
  35          * @param $id
  36          *
  37          * @return object
  38          */
  39         static function getInstance( $id ) {
  40                 if ( isset( self::$instances[$id] ) ) {
  41                         return self::$instances[$id];
  42                 }
  43
  44                 $object = self::newFromId( $id );
  45                 self::$instances[$id] = $object;
  46                 return $object;
  47         }
  48
  49         /**
  50          * Clear all the cached instances.
  51          */
  52         static function clear() {
  53                 self::$instances = array();
  54         }
  55
  56         /**
  57          * Create a new cache object of the specified type.
  58          *
  59          * @param $id
  60          *
  61          * @return ObjectCache
  62          */
  63         static function newFromId( $id ) {
  64                 global $wgObjectCaches;
  65
  66                 if ( !isset( $wgObjectCaches[$id] ) ) {
  67                         throw new MWException( "Invalid object cache type \"$id\" requested. " .
  68                                 "It is not present in \$wgObjectCaches." );
  69                 }
  70
  71                 return self::newFromParams( $wgObjectCaches[$id] );
  72         }
  73
  74         /**
  75          * Create a new cache object from parameters
  76          *
  77          * @param $params array
  78          *
  79          * @return ObjectCache
  80          */
  81         static function newFromParams( $params ) {
  82                 if ( isset( $params['factory'] ) ) {
  83                         return call_user_func( $params['factory'], $params );
  84                 } elseif ( isset( $params['class'] ) ) {
  85                         $class = $params['class'];
  86                         return new $class( $params );
  87                 } else {
  88                         throw new MWException( "The definition of cache type \"" . print_r( $params, true ) . "\" lacks both " .
  89                                 "factory and class parameters." );
  90                 }
  91         }
  92
  93         /**
  94          * Factory function referenced from DefaultSettings.php for CACHE_ANYTHING
  95          *
  96          * CACHE_ANYTHING means that stuff has to be cached, not caching is not an option.
  97          * If a caching method is configured for any of the main caches ($wgMainCacheType,
  98          * $wgMessageCacheType, $wgParserCacheType), then CACHE_ANYTHING will effectively
  99          * be an alias to the configured cache choice for that.
 100          * If no cache choice is configured (by default $wgMainCacheType is CACHE_NONE),
 101          * then CACHE_ANYTHING will forward to CACHE_DB.
 102          */
 103         static function newAnything( $params ) {
 104                 global $wgMainCacheType, $wgMessageCacheType, $wgParserCacheType;
 105                 $candidates = array( $wgMainCacheType, $wgMessageCacheType, $wgParserCacheType );
 106                 foreach ( $candidates as $candidate ) {
 107                         if ( $candidate !== CACHE_NONE && $candidate !== CACHE_ANYTHING ) {
 108                                 return self::getInstance( $candidate );
 109                         }
 110                 }
 111                 return self::getInstance( CACHE_DB );
 112         }
 113
 114         /**
 115          * Factory function referenced from DefaultSettings.php for CACHE_ACCEL.
 116          *
 117          * @return ObjectCache
 118          */
 119         static function newAccelerator( $params ) {
 120                 if ( function_exists( 'apc_fetch') ) {
 121                         $id = 'apc';
 122                 } elseif( function_exists( 'xcache_get' ) && wfIniGetBool( 'xcache.var_size' ) ) {
 123                         $id = 'xcache';
 124                 } elseif( function_exists( 'wincache_ucache_get' ) ) {
 125                         $id = 'wincache';
 126                 } else {
 127                         throw new MWException( "CACHE_ACCEL requested but no suitable object " .
 128                                 "cache is present. You may want to install APC." );
 129                 }
 130                 return self::newFromId( $id );
 131         }
 132
 133         /**
 134          * Factory function that creates a memcached client object.
 135          *
 136          * This always uses the PHP client, since the PECL client has a different
 137          * hashing scheme and a different interpretation of the flags bitfield, so
 138          * switching between the two clients randomly would be disasterous.
 139          *
 140          * @param $params array
 141          *
 142          * @return MemcachedPhpBagOStuff
 143          */
 144         static function newMemcached( $params ) {
 145                 return new MemcachedPhpBagOStuff( $params );
 146         }
 147 }