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          */
  53         static function getCache() {
  54                 global $wgSessionCacheType;
  55                 return ObjectCache::getInstance( $wgSessionCacheType );
  56         }
  57
  58         /**
  59          * Get a cache key for the given session id.
  60          *
  61          * @param string $id session id
  62          * @return String: cache key
  63          */
  64         static function getKey( $id ) {
  65                 return wfMemcKey( 'session', $id );
  66         }
  67
  68         /**
  69          * Callback when opening a session.
  70          *
  71          * @param $save_path String: path used to store session files, unused
  72          * @param $session_name String: session name
  73          * @return Boolean: success
  74          */
  75         static function open( $save_path, $session_name ) {
  76                 return true;
  77         }
  78
  79         /**
  80          * Callback when closing a session.
  81          * NOP.
  82          *
  83          * @return Boolean: success
  84          */
  85         static function close() {
  86                 return true;
  87         }
  88
  89         /**
  90          * Callback when reading session data.
  91          *
  92          * @param string $id session id
  93          * @return Mixed: session data
  94          */
  95         static function read( $id ) {
  96                 $data = self::getCache()->get( self::getKey( $id ) );
  97                 if ( $data === false ) {
  98                         return '';
  99                 }
 100                 return $data;
 101         }
 102
 103         /**
 104          * Callback when writing session data.
 105          *
 106          * @param string $id session id
 107          * @param $data Mixed: session data
 108          * @return Boolean: success
 109          */
 110         static function write( $id, $data ) {
 111                 global $wgObjectCacheSessionExpiry;
 112                 self::getCache()->set( self::getKey( $id ), $data, $wgObjectCacheSessionExpiry );
 113                 return true;
 114         }
 115
 116         /**
 117          * Callback to destroy a session when calling session_destroy().
 118          *
 119          * @param string $id session id
 120          * @return Boolean: success
 121          */
 122         static function destroy( $id ) {
 123                 self::getCache()->delete( self::getKey( $id ) );
 124                 return true;
 125         }
 126
 127         /**
 128          * Callback to execute garbage collection.
 129          * NOP: Object caches perform garbage collection implicitly
 130          *
 131          * @param $maxlifetime Integer: maximum session life time
 132          * @return Boolean: success
 133          */
 134         static function gc( $maxlifetime ) {
 135                 return true;
 136         }
 137
 138         /**
 139          * Shutdown function. See the comment inside ObjectCacheSessionHandler::install
 140          * for rationale.
 141          */
 142         static function handleShutdown() {
 143                 session_write_close();
 144         }
 145 }