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   1  <?php
   2  /**
   3   * Session storage in object cache.
   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   * Session storage in object cache.
  26   * Used if $wgSessionsInObjectCache is true.
  27   *
  28   * @ingroup Cache
  29   */
  30  class ObjectCacheSessionHandler {
  31      /**
  32       * Install a session handler for the current web request
  33       */
  34  	static function install() {
  35          session_set_save_handler(
  36              array( __CLASS__, 'open' ),
  37              array( __CLASS__, 'close' ),
  38              array( __CLASS__, 'read' ),
  39              array( __CLASS__, 'write' ),
  40              array( __CLASS__, 'destroy' ),
  41              array( __CLASS__, 'gc' ) );
  42  
  43          // It's necessary to register a shutdown function to call session_write_close(),
  44          // because by the time the request shutdown function for the session module is
  45          // called, $wgMemc has already been destroyed. Shutdown functions registered
  46          // this way are called before object destruction.
  47          register_shutdown_function( array( __CLASS__, 'handleShutdown' ) );
  48      }
  49  
  50      /**
  51       * Get the cache storage object to use for session storage
  52       * @return ObjectCache
  53       */
  54  	static function getCache() {
  55          global $wgSessionCacheType;
  56          return ObjectCache::getInstance( $wgSessionCacheType );
  57      }
  58  
  59      /**
  60       * Get a cache key for the given session id.
  61       *
  62       * @param string $id Session id
  63       * @return string Cache key
  64       */
  65  	static function getKey( $id ) {
  66          return wfMemcKey( 'session', $id );
  67      }
  68  
  69      /**
  70       * Callback when opening a session.
  71       *
  72       * @param string $save_path Path used to store session files, unused
  73       * @param string $session_name Session name
  74       * @return bool Success
  75       */
  76  	static function open( $save_path, $session_name ) {
  77          return true;
  78      }
  79  
  80      /**
  81       * Callback when closing a session.
  82       * NOP.
  83       *
  84       * @return bool Success
  85       */
  86  	static function close() {
  87          return true;
  88      }
  89  
  90      /**
  91       * Callback when reading session data.
  92       *
  93       * @param string $id Session id
  94       * @return mixed Session data
  95       */
  96  	static function read( $id ) {
  97          $data = self::getCache()->get( self::getKey( $id ) );
  98          if ( $data === false ) {
  99              return '';
 100          }
 101          return $data;
 102      }
 103  
 104      /**
 105       * Callback when writing session data.
 106       *
 107       * @param string $id Session id
 108       * @param mixed $data Session data
 109       * @return bool Success
 110       */
 111  	static function write( $id, $data ) {
 112          global $wgObjectCacheSessionExpiry;
 113          self::getCache()->set( self::getKey( $id ), $data, $wgObjectCacheSessionExpiry );
 114          return true;
 115      }
 116  
 117      /**
 118       * Callback to destroy a session when calling session_destroy().
 119       *
 120       * @param string $id Session id
 121       * @return bool Success
 122       */
 123  	static function destroy( $id ) {
 124          self::getCache()->delete( self::getKey( $id ) );
 125          return true;
 126      }
 127  
 128      /**
 129       * Callback to execute garbage collection.
 130       * NOP: Object caches perform garbage collection implicitly
 131       *
 132       * @param int $maxlifetime Maximum session life time
 133       * @return bool Success
 134       */
 135      static function gc( $maxlifetime ) {
 136          return true;
 137      }
 138  
 139      /**
 140       * Shutdown function. See the comment inside ObjectCacheSessionHandler::install
 141       * for rationale.
 142       */
 143  	static function handleShutdown() {
 144          session_write_close();
 145      }
 146  }