includes/objectcache/ObjectCacheSessionHandler.php

   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 }