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         public static $instances = array();
  31
  32         /**
  33          * Get a cached instance of the specified type of cache object.
  34          *
  35          * @param string $id
  36          *
  37          * @return BagOStuff
  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 string $id
  60          *
  61          * @throws MWException
  62          * @return BagOStuff
  63          */
  64         static function newFromId( $id ) {
  65                 global $wgObjectCaches;
  66
  67                 if ( !isset( $wgObjectCaches[$id] ) ) {
  68                         throw new MWException( "Invalid object cache type \"$id\" requested. " .
  69                                 "It is not present in \$wgObjectCaches." );
  70                 }
  71
  72                 return self::newFromParams( $wgObjectCaches[$id] );
  73         }
  74
  75         /**
  76          * Create a new cache object from parameters
  77          *
  78          * @param array $params
  79          *
  80          * @throws MWException
  81          * @return BagOStuff
  82          */
  83         static function newFromParams( $params ) {
  84                 if ( isset( $params['factory'] ) ) {
  85                         return call_user_func( $params['factory'], $params );
  86                 } elseif ( isset( $params['class'] ) ) {
  87                         $class = $params['class'];
  88                         return new $class( $params );
  89                 } else {
  90                         throw new MWException( "The definition of cache type \""
  91                                 . print_r( $params, true ) . "\" lacks both "
  92                                 . "factory and class parameters." );
  93                 }
  94         }
  95
  96         /**
  97          * Factory function referenced from DefaultSettings.php for CACHE_ANYTHING
  98          *
  99          * CACHE_ANYTHING means that stuff has to be cached, not caching is not an option.
 100          * If a caching method is configured for any of the main caches ($wgMainCacheType,
 101          * $wgMessageCacheType, $wgParserCacheType), then CACHE_ANYTHING will effectively
 102          * be an alias to the configured cache choice for that.
 103          * If no cache choice is configured (by default $wgMainCacheType is CACHE_NONE),
 104          * then CACHE_ANYTHING will forward to CACHE_DB.
 105          * @param array $params
 106          * @return BagOStuff
 107          */
 108         static function newAnything( $params ) {
 109                 global $wgMainCacheType, $wgMessageCacheType, $wgParserCacheType;
 110                 $candidates = array( $wgMainCacheType, $wgMessageCacheType, $wgParserCacheType );
 111                 foreach ( $candidates as $candidate ) {
 112                         if ( $candidate !== CACHE_NONE && $candidate !== CACHE_ANYTHING ) {
 113                                 return self::getInstance( $candidate );
 114                         }
 115                 }
 116                 return self::getInstance( CACHE_DB );
 117         }
 118
 119         /**
 120          * Factory function referenced from DefaultSettings.php for CACHE_ACCEL.
 121          *
 122          * This will look for any APC style server-local cache.
 123          * A fallback cache can be specified if none is found.
 124          *
 125          * @param array $params
 126          * @param int|string $fallback Fallback cache, e.g. (CACHE_NONE, "hash") (since 1.24)
 127          * @throws MWException
 128          * @return BagOStuff
 129          */
 130         static function newAccelerator( $params, $fallback = null ) {
 131                 if ( function_exists( 'apc_fetch' ) ) {
 132                         $id = 'apc';
 133                 } elseif ( function_exists( 'xcache_get' ) && wfIniGetBool( 'xcache.var_size' ) ) {
 134                         $id = 'xcache';
 135                 } elseif ( function_exists( 'wincache_ucache_get' ) ) {
 136                         $id = 'wincache';
 137                 } else {
 138                         if ( $fallback ) {
 139                                 return self::newFromId( $fallback );
 140                         }
 141                         throw new MWException( "CACHE_ACCEL requested but no suitable object " .
 142                                 "cache is present. You may want to install APC." );
 143                 }
 144                 return self::newFromId( $id );
 145         }
 146
 147         /**
 148          * Factory function that creates a memcached client object.
 149          *
 150          * This always uses the PHP client, since the PECL client has a different
 151          * hashing scheme and a different interpretation of the flags bitfield, so
 152          * switching between the two clients randomly would be disastrous.
 153          *
 154          * @param array $params
 155          *
 156          * @return MemcachedPhpBagOStuff
 157          */
 158         static function newMemcached( $params ) {
 159                 return new MemcachedPhpBagOStuff( $params );
 160         }
 161 }