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 use MediaWiki\Logger\LoggerFactory;
  25
  26 /**
  27  * Functions to get cache objects
  28  *
  29  * @ingroup Cache
  30  */
  31 class ObjectCache {
  32         public static $instances = array();
  33
  34         /**
  35          * Get a cached instance of the specified type of cache object.
  36          *
  37          * @param string $id
  38          *
  39          * @return BagOStuff
  40          */
  41         static function getInstance( $id ) {
  42                 if ( isset( self::$instances[$id] ) ) {
  43                         return self::$instances[$id];
  44                 }
  45
  46                 $object = self::newFromId( $id );
  47                 self::$instances[$id] = $object;
  48                 return $object;
  49         }
  50
  51         /**
  52          * Clear all the cached instances.
  53          */
  54         static function clear() {
  55                 self::$instances = array();
  56         }
  57
  58         /**
  59          * Create a new cache object of the specified type.
  60          *
  61          * @param string $id
  62          *
  63          * @throws MWException
  64          * @return BagOStuff
  65          */
  66         static function newFromId( $id ) {
  67                 global $wgObjectCaches;
  68
  69                 if ( !isset( $wgObjectCaches[$id] ) ) {
  70                         throw new MWException( "Invalid object cache type \"$id\" requested. " .
  71                                 "It is not present in \$wgObjectCaches." );
  72                 }
  73
  74                 return self::newFromParams( $wgObjectCaches[$id] );
  75         }
  76
  77         /**
  78          * Create a new cache object from parameters
  79          *
  80          * @param array $params
  81          *
  82          * @throws MWException
  83          * @return BagOStuff
  84          */
  85         static function newFromParams( $params ) {
  86                 if ( isset( $params['loggroup'] ) ) {
  87                         $params['logger'] = LoggerFactory::getInstance( $params['loggroup'] );
  88                 } else {
  89                         // For backwards-compatability with custom parameters, lets not
  90                         // have all logging suddenly disappear
  91                         $params['logger'] = LoggerFactory::getInstance( 'objectcache' );
  92                 }
  93                 if ( isset( $params['factory'] ) ) {
  94                         return call_user_func( $params['factory'], $params );
  95                 } elseif ( isset( $params['class'] ) ) {
  96                         $class = $params['class'];
  97                         return new $class( $params );
  98                 } else {
  99                         throw new MWException( "The definition of cache type \""
 100                                 . print_r( $params, true ) . "\" lacks both "
 101                                 . "factory and class parameters." );
 102                 }
 103         }
 104
 105         /**
 106          * Factory function referenced from DefaultSettings.php for CACHE_ANYTHING
 107          *
 108          * CACHE_ANYTHING means that stuff has to be cached, not caching is not an option.
 109          * If a caching method is configured for any of the main caches ($wgMainCacheType,
 110          * $wgMessageCacheType, $wgParserCacheType), then CACHE_ANYTHING will effectively
 111          * be an alias to the configured cache choice for that.
 112          * If no cache choice is configured (by default $wgMainCacheType is CACHE_NONE),
 113          * then CACHE_ANYTHING will forward to CACHE_DB.
 114          * @param array $params
 115          * @return BagOStuff
 116          */
 117         static function newAnything( $params ) {
 118                 global $wgMainCacheType, $wgMessageCacheType, $wgParserCacheType;
 119                 $candidates = array( $wgMainCacheType, $wgMessageCacheType, $wgParserCacheType );
 120                 foreach ( $candidates as $candidate ) {
 121                         if ( $candidate !== CACHE_NONE && $candidate !== CACHE_ANYTHING ) {
 122                                 return self::getInstance( $candidate );
 123                         }
 124                 }
 125                 return self::getInstance( CACHE_DB );
 126         }
 127
 128         /**
 129          * Factory function referenced from DefaultSettings.php for CACHE_ACCEL.
 130          *
 131          * This will look for any APC style server-local cache.
 132          * A fallback cache can be specified if none is found.
 133          *
 134          * @param array $params
 135          * @param int|string $fallback Fallback cache, e.g. (CACHE_NONE, "hash") (since 1.24)
 136          * @throws MWException
 137          * @return BagOStuff
 138          */
 139         static function newAccelerator( $params, $fallback = null ) {
 140                 if ( function_exists( 'apc_fetch' ) ) {
 141                         $id = 'apc';
 142                 } elseif ( function_exists( 'xcache_get' ) && wfIniGetBool( 'xcache.var_size' ) ) {
 143                         $id = 'xcache';
 144                 } elseif ( function_exists( 'wincache_ucache_get' ) ) {
 145                         $id = 'wincache';
 146                 } else {
 147                         if ( $fallback !== null ) {
 148                                 return self::newFromId( $fallback );
 149                         }
 150                         throw new MWException( "CACHE_ACCEL requested but no suitable object " .
 151                                 "cache is present. You may want to install APC." );
 152                 }
 153                 return self::newFromId( $id );
 154         }
 155
 156         /**
 157          * Factory function that creates a memcached client object.
 158          *
 159          * This always uses the PHP client, since the PECL client has a different
 160          * hashing scheme and a different interpretation of the flags bitfield, so
 161          * switching between the two clients randomly would be disastrous.
 162          *
 163          * @param array $params
 164          *
 165          * @return MemcachedPhpBagOStuff
 166          */
 167         static function newMemcached( $params ) {
 168                 return new MemcachedPhpBagOStuff( $params );
 169         }
 170 }