[Summary view] [Print] [Text view]

   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  }