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 class ObjectCacheSessionHandler {
  24         /**
  25          * Install a session handler for the current web request
  26          */
  27         static function install() {
  28                 session_set_save_handler(
  29                         array( __CLASS__, 'open' ),
  30                         array( __CLASS__, 'close' ),
  31                         array( __CLASS__, 'read' ),
  32                         array( __CLASS__, 'write' ),
  33                         array( __CLASS__, 'destroy' ),
  34                         array( __CLASS__, 'gc' ) );
  35
  36                 // It's necessary to register a shutdown function to call session_write_close(),
  37                 // because by the time the request shutdown function for the session module is
  38                 // called, $wgMemc has already been destroyed. Shutdown functions registered
  39                 // this way are called before object destruction.
  40                 register_shutdown_function( array( __CLASS__, 'handleShutdown' ) );
  41         }
  42
  43         /**
  44          * Get the cache storage object to use for session storage
  45          */
  46         static function getCache() {
  47                 global $wgSessionCacheType;
  48                 return ObjectCache::getInstance( $wgSessionCacheType );
  49         }
  50
  51         /**
  52          * Get a cache key for the given session id.
  53          *
  54          * @param $id String: session id
  55          * @return String: cache key
  56          */
  57         static function getKey( $id ) {
  58                 return wfMemcKey( 'session', $id );
  59         }
  60
  61         /**
  62          * Callback when opening a session.
  63          *
  64          * @param $save_path String: path used to store session files, unused
  65          * @param $session_name String: session name
  66          * @return Boolean: success
  67          */
  68         static function open( $save_path, $session_name ) {
  69                 return true;
  70         }
  71
  72         /**
  73          * Callback when closing a session.
  74          * NOP.
  75          *
  76          * @return Boolean: success
  77          */
  78         static function close() {
  79                 return true;
  80         }
  81
  82         /**
  83          * Callback when reading session data.
  84          *
  85          * @param $id String: session id
  86          * @return Mixed: session data
  87          */
  88         static function read( $id ) {
  89                 $data = self::getCache()->get( self::getKey( $id ) );
  90                 if( $data === false ) {
  91                         return '';
  92                 }
  93                 return $data;
  94         }
  95
  96         /**
  97          * Callback when writing session data.
  98          *
  99          * @param $id String: session id
 100          * @param $data Mixed: session data
 101          * @return Boolean: success
 102          */
 103         static function write( $id, $data ) {
 104                 global $wgObjectCacheSessionExpiry;
 105                 self::getCache()->set( self::getKey( $id ), $data, $wgObjectCacheSessionExpiry );
 106                 return true;
 107         }
 108
 109         /**
 110          * Callback to destroy a session when calling session_destroy().
 111          *
 112          * @param $id String: session id
 113          * @return Boolean: success
 114          */
 115         static function destroy( $id ) {
 116                 self::getCache()->delete( self::getKey( $id ) );
 117                 return true;
 118         }
 119
 120         /**
 121          * Callback to execute garbage collection.
 122          * NOP: Object caches perform garbage collection implicitly
 123          *
 124          * @param $maxlifetime Integer: maximum session life time
 125          * @return Boolean: success
 126          */
 127         static function gc( $maxlifetime ) {
 128                 return true;
 129         }
 130
 131         /**
 132          * Shutdown function. See the comment inside ObjectCacheSessionHandler::install
 133          * for rationale.
 134          */
 135         static function handleShutdown() {
 136                 session_write_close();
 137         }
 138 }