From: Aaron Schulz <aschulz@wikimedia.org>
Date: Tue, 11 Aug 2015 00:49:19 +0000 (-0700)
Subject: Restored I4afaecd8: "Avoiding writing sessions for no reason"
X-Git-Tag: 1.31.0-rc.0~10453
X-Git-Url: http://git.cyclocoop.org/%7B%24www_url%7Dadmin/compta/categories/modifier.php?a=commitdiff_plain;h=08039b2df44a2e83974d77fccba337a5d86cd854;p=lhc%2Fweb%2Fwiklou.git

Restored I4afaecd8: "Avoiding writing sessions for no reason"

* After 203d2c9c11643, the refresh updates should actually trigger

This reverts commit e48fec5a8ab5916735849d420f2dfeec7eb0fced.

Change-Id: I8427ed5b3a5bb80033cbdf071a33f8a3999ecb97
---

diff --git a/includes/objectcache/ObjectCacheSessionHandler.php b/includes/objectcache/ObjectCacheSessionHandler.php
index 8a7b2980b6..1f4beb9dec 100644
--- a/includes/objectcache/ObjectCacheSessionHandler.php
+++ b/includes/objectcache/ObjectCacheSessionHandler.php
@@ -30,6 +30,9 @@ use MediaWiki\Logger\LoggerFactory;
  * @ingroup Cache
  */
 class ObjectCacheSessionHandler {
+	/** @var array Map of (session ID => SHA-1 of the data) */
+	protected static $hashCache = array();
+
 	/**
 	 * Install a session handler for the current web request
 	 */
@@ -55,6 +58,7 @@ class ObjectCacheSessionHandler {
 	 */
 	protected static function getCache() {
 		global $wgSessionCacheType;
+
 		return ObjectCache::getInstance( $wgSessionCacheType );
 	}
 
@@ -68,6 +72,14 @@ class ObjectCacheSessionHandler {
 		return wfMemcKey( 'session', $id );
 	}
 
+	/**
+	 * @param mixed $data
+	 * @return string
+	 */
+	protected static function getHash( $data ) {
+		return sha1( serialize( $data ) );
+	}
+
 	/**
 	 * Callback when opening a session.
 	 *
@@ -97,10 +109,10 @@ class ObjectCacheSessionHandler {
 	 */
 	static function read( $id ) {
 		$data = self::getCache()->get( self::getKey( $id ) );
-		if ( $data === false ) {
-			return '';
-		}
-		return $data;
+
+		self::$hashCache = array( $id => self::getHash( $data ) );
+
+		return ( $data === false ) ? '' : $data;
 	}
 
 	/**
@@ -112,7 +124,14 @@ class ObjectCacheSessionHandler {
 	 */
 	static function write( $id, $data ) {
 		global $wgObjectCacheSessionExpiry;
-		self::getCache()->set( self::getKey( $id ), $data, $wgObjectCacheSessionExpiry );
+
+		// Only issue a write if anything changed (PHP 5.6 already does this)
+		if ( !isset( self::$hashCache[$id] )
+			|| self::getHash( $data ) !== self::$hashCache[$id]
+		) {
+			self::getCache()->set( self::getKey( $id ), $data, $wgObjectCacheSessionExpiry );
+		}
+
 		return true;
 	}