From 6eb6313b6f9f8b42dc58bea3f432235b954a2d5c Mon Sep 17 00:00:00 2001
From: Tim Starling <tstarling@wikimedia.org>
Date: Tue, 7 Aug 2012 15:25:46 +1000
Subject: [PATCH] Allow session storage to be configured independently

* Introduce $wgSessionCacheType to allow the session storage to be
  configured independently of $wgMemc.
* Renamed $wgSessionsInMemcached to $wgSessionsInObjectCache to reflect
  the new versatility.
* Modernized the relevant code, removing the explicit require_once(),
  used the autoloader instead. Moved it to ObjectCacheSessionHandler.
* Tested with memcached, external sharded MySQL and APC, it all seems to
  work just fine.

Change-Id: I473334bb56cafb4e21ac1c1304d69095676fc0c4
---
 RELEASE-NOTES-1.20                            |   4 +
 includes/AutoLoader.php                       |   1 +
 includes/DefaultSettings.php                  |  21 ++-
 includes/GlobalFunctions.php                  |  17 +--
 includes/cache/MemcachedSessions.php          | 115 ---------------
 .../objectcache/ObjectCacheSessionHandler.php | 137 ++++++++++++++++++
 6 files changed, 163 insertions(+), 132 deletions(-)
 delete mode 100644 includes/cache/MemcachedSessions.php
 create mode 100644 includes/objectcache/ObjectCacheSessionHandler.php

diff --git a/RELEASE-NOTES-1.20 b/RELEASE-NOTES-1.20
index 5a76c84e2d..c52ff60970 100644
--- a/RELEASE-NOTES-1.20
+++ b/RELEASE-NOTES-1.20
@@ -108,6 +108,10 @@ upgrade PHP if you have not done so prior to upgrading MediaWiki.
 * Added support in jquery.localize for placeholder attributes.
 * (bug 38151) Implemented mw.user.getRights for getting and caching the current
   user's user rights.
+* Session storage can now configured independently of general object cache 
+  storage, by using $wgSessionCacheType. $wgSessionsInMemcached has been 
+  renamed to $wgSessionsInObjectCache, with the old name retained for backwards
+  compatibility.
 * Implemented mw.user.getGroups for getting and caching user groups.
 * (bug 37830) Added $wgRequirePasswordforEmailChange to control whether password
   confirmation is required for changing an email address or not.
diff --git a/includes/AutoLoader.php b/includes/AutoLoader.php
index e9e0440bb5..e50430eb23 100644
--- a/includes/AutoLoader.php
+++ b/includes/AutoLoader.php
@@ -731,6 +731,7 @@ $wgAutoloadLocalClasses = array(
 	'MultiWriteBagOStuff' => 'includes/objectcache/MultiWriteBagOStuff.php',
 	'MWMemcached' => 'includes/objectcache/MemcachedClient.php',
 	'ObjectCache' => 'includes/objectcache/ObjectCache.php',
+	'ObjectCacheSessionHandler' => 'includes/objectcache/ObjectCacheSessionHandler.php',
 	'SqlBagOStuff' => 'includes/objectcache/SqlBagOStuff.php',
 	'WinCacheBagOStuff' => 'includes/objectcache/WinCacheBagOStuff.php',
 	'XCacheBagOStuff' => 'includes/objectcache/XCacheBagOStuff.php',
diff --git a/includes/DefaultSettings.php b/includes/DefaultSettings.php
index ffe22cad55..dda191e4f1 100644
--- a/includes/DefaultSettings.php
+++ b/includes/DefaultSettings.php
@@ -1659,6 +1659,13 @@ $wgMessageCacheType = CACHE_ANYTHING;
  */
 $wgParserCacheType = CACHE_ANYTHING;
 
+/**
+ * The cache type for storing session data. Used if $wgSessionsInObjectCache is true.
+ *
+ * For available types see $wgMainCacheType.
+ */
+$wgSessionCacheType = CACHE_ANYTHING;
+
 /**
  * The cache type for storing language conversion tables,
  * which are used when parsing certain text and interface messages.
@@ -1714,12 +1721,20 @@ $wgParserCacheExpireTime = 86400;
 $wgDBAhandler = 'db3';
 
 /**
- * Store sessions in MemCached. This can be useful to improve performance, or to
- * avoid the locking behaviour of PHP's default session handler, which tends to
- * prevent multiple requests for the same user from acting concurrently.
+ * Deprecated alias for $wgSessionsInObjectCache.
+ *
+ * @deprecated Use $wgSessionsInObjectCache
  */
 $wgSessionsInMemcached = false;
 
+/**
+ * Store sessions in an object cache, configured by $wgSessionCacheType. This
+ * can be useful to improve performance, or to avoid the locking behaviour of
+ * PHP's default session handler, which tends to prevent multiple requests for
+ * the same user from acting concurrently.
+ */
+$wgSessionsInObjectCache = false;
+
 /**
  * This is used for setting php's session.save_handler. In practice, you will
  * almost never need to change this ever. Other options might be 'user' or
diff --git a/includes/GlobalFunctions.php b/includes/GlobalFunctions.php
index e25ce26685..3e2b63e71b 100644
--- a/includes/GlobalFunctions.php
+++ b/includes/GlobalFunctions.php
@@ -3372,21 +3372,10 @@ function wfFixSessionID() {
  * @param $sessionId Bool
  */
 function wfSetupSession( $sessionId = false ) {
-	global $wgSessionsInMemcached, $wgCookiePath, $wgCookieDomain,
+	global $wgSessionsInMemcached, $wgSessionsInObjectCache, $wgCookiePath, $wgCookieDomain,
 			$wgCookieSecure, $wgCookieHttpOnly, $wgSessionHandler;
-	if( $wgSessionsInMemcached ) {
-		if ( !defined( 'MW_COMPILED' ) ) {
-			global $IP;
-			require_once( "$IP/includes/cache/MemcachedSessions.php" );
-		}
-		session_set_save_handler( 'memsess_open', 'memsess_close', 'memsess_read',
-			'memsess_write', 'memsess_destroy', 'memsess_gc' );
-
-		// It's necessary to register a shutdown function to call session_write_close(),
-		// because by the time the request shutdown function for the session module is
-		// called, $wgMemc has already been destroyed. Shutdown functions registered
-		// this way are called before object destruction.
-		register_shutdown_function( 'memsess_write_close' );
+	if( $wgSessionsInObjectCache || $wgSessionsInMemcached ) {
+		ObjectCacheSessionHandler::install();
 	} elseif( $wgSessionHandler && $wgSessionHandler != ini_get( 'session.save_handler' ) ) {
 		# Only set this if $wgSessionHandler isn't null and session.save_handler
 		# hasn't already been set to the desired value (that causes errors)
diff --git a/includes/cache/MemcachedSessions.php b/includes/cache/MemcachedSessions.php
deleted file mode 100644
index fe43635422..0000000000
--- a/includes/cache/MemcachedSessions.php
+++ /dev/null
@@ -1,115 +0,0 @@
-<?php
-/**
- * Session storage in object cache.
- *
- * This file gets included if $wgSessionsInMemcache is set in the config.
- * It redirects session handling functions to store their data in memcached
- * instead of the local filesystem. Depending on circumstances, it may also
- * be necessary to change the cookie settings to work across hostnames.
- * See: http://www.php.net/manual/en/function.session-set-save-handler.php
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License along
- * with this program; if not, write to the Free Software Foundation, Inc.,
- * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
- * http://www.gnu.org/copyleft/gpl.html
- *
- * @file
- * @ingroup Cache
- */
-
-/**
- * Get a cache key for the given session id.
- *
- * @param $id String: session id
- * @return String: cache key
- */
-function memsess_key( $id ) {
-	return wfMemcKey( 'session', $id );
-}
-
-/**
- * Callback when opening a session.
- * NOP: $wgMemc should be set up already.
- *
- * @param $save_path String: path used to store session files, unused
- * @param $session_name String: session name
- * @return Boolean: success
- */
-function memsess_open( $save_path, $session_name ) {
-	return true;
-}
-
-/**
- * Callback when closing a session.
- * NOP.
- *
- * @return Boolean: success
- */
-function memsess_close() {
-	return true;
-}
-
-/**
- * Callback when reading session data.
- *
- * @param $id String: session id
- * @return Mixed: session data
- */
-function memsess_read( $id ) {
-	global $wgMemc;
-	$data = $wgMemc->get( memsess_key( $id ) );
-	if( ! $data ) return '';
-	return $data;
-}
-
-/**
- * Callback when writing session data.
- *
- * @param $id String: session id
- * @param $data Mixed: session data
- * @return Boolean: success
- */
-function memsess_write( $id, $data ) {
-	global $wgMemc;
-	$wgMemc->set( memsess_key( $id ), $data, 3600 );
-	return true;
-}
-
-/**
- * Callback to destroy a session when calling session_destroy().
- *
- * @param $id String: session id
- * @return Boolean: success
- */
-function memsess_destroy( $id ) {
-	global $wgMemc;
-
-	$wgMemc->delete( memsess_key( $id ) );
-	return true;
-}
-
-/**
- * Callback to execute garbage collection.
- * NOP: Memcached performs garbage collection.
- *
- * @param $maxlifetime Integer: maximum session life time
- * @return Boolean: success
- */
-function memsess_gc( $maxlifetime ) {
-	return true;
-}
-
-function memsess_write_close() {
-	session_write_close();
-}
-
diff --git a/includes/objectcache/ObjectCacheSessionHandler.php b/includes/objectcache/ObjectCacheSessionHandler.php
new file mode 100644
index 0000000000..3dcfa9f690
--- /dev/null
+++ b/includes/objectcache/ObjectCacheSessionHandler.php
@@ -0,0 +1,137 @@
+<?php
+/*
+ * Session storage in object cache.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ * @ingroup Cache
+ */
+class ObjectCacheSessionHandler {
+	/**
+	 * Install a session handler for the current web request
+	 */
+	static function install() {
+		session_set_save_handler(
+			array( __CLASS__, 'open' ),
+			array( __CLASS__, 'close' ),
+			array( __CLASS__, 'read' ),
+			array( __CLASS__, 'write' ),
+			array( __CLASS__, 'destroy' ),
+			array( __CLASS__, 'gc' ) );
+
+		// It's necessary to register a shutdown function to call session_write_close(),
+		// because by the time the request shutdown function for the session module is
+		// called, $wgMemc has already been destroyed. Shutdown functions registered
+		// this way are called before object destruction.
+		register_shutdown_function( array( __CLASS__, 'handleShutdown' ) );
+	}
+
+	/**
+	 * Get the cache storage object to use for session storage
+	 */
+	static function getCache() {
+		global $wgSessionCacheType;
+		return ObjectCache::getInstance( $wgSessionCacheType );
+	}
+
+	/**
+	 * Get a cache key for the given session id.
+	 *
+	 * @param $id String: session id
+	 * @return String: cache key
+	 */
+	static function getKey( $id ) {
+		return wfMemcKey( 'session', $id );
+	}
+
+	/**
+	 * Callback when opening a session.
+	 *
+	 * @param $save_path String: path used to store session files, unused
+	 * @param $session_name String: session name
+	 * @return Boolean: success
+	 */
+	static function open( $save_path, $session_name ) {
+		return true;
+	}
+
+	/**
+	 * Callback when closing a session.
+	 * NOP.
+	 *
+	 * @return Boolean: success
+	 */
+	static function close() {
+		return true;
+	}
+
+	/**
+	 * Callback when reading session data.
+	 *
+	 * @param $id String: session id
+	 * @return Mixed: session data
+	 */
+	static function read( $id ) {
+		$data = self::getCache()->get( self::getKey( $id ) );
+		if( $data === false ) {
+			return '';
+		}
+		return $data;
+	}
+
+	/**
+	 * Callback when writing session data.
+	 *
+	 * @param $id String: session id
+	 * @param $data Mixed: session data
+	 * @return Boolean: success
+	 */
+	static function write( $id, $data ) {
+		self::getCache()->set( self::getKey( $id ), $data, 3600 );
+		return true;
+	}
+
+	/**
+	 * Callback to destroy a session when calling session_destroy().
+	 *
+	 * @param $id String: session id
+	 * @return Boolean: success
+	 */
+	static function destroy( $id ) {
+		self::getCache()->delete( self::getKey( $id ) );
+		return true;
+	}
+
+	/**
+	 * Callback to execute garbage collection.
+	 * NOP: Object caches perform garbage collection implicitly
+	 *
+	 * @param $maxlifetime Integer: maximum session life time
+	 * @return Boolean: success
+	 */
+	static function gc( $maxlifetime ) {
+		return true;
+	}
+
+	/**
+	 * Shutdown function. See the comment inside ObjectCacheSessionHandler::install 
+	 * for rationale.
+	 */
+	static function handleShutdown() {
+		session_write_close();
+	}
+}
-- 
2.20.1