From 9db190c7e736ec8d063187d4241b59feaf7dc2d1 Mon Sep 17 00:00:00 2001
From: Pierre Schmitz <pierre@archlinux.de>
Date: Wed, 22 Jun 2011 11:28:20 +0200
Subject: update to MediaWiki 1.17.0

---
 includes/db/LBFactory.php | 76 ++++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 68 insertions(+), 8 deletions(-)

(limited to 'includes/db/LBFactory.php')

diff --git a/includes/db/LBFactory.php b/includes/db/LBFactory.php
index 10c87133..f84a70e5 100644
--- a/includes/db/LBFactory.php
+++ b/includes/db/LBFactory.php
@@ -1,5 +1,7 @@
 <?php
 /**
+ * Generator of database load balancing objects
+ *
  * @file
  * @ingroup Database
  */
@@ -11,6 +13,23 @@
 abstract class LBFactory {
 	static $instance;
 
+	/**
+	 * Disables all access to the load balancer, will cause all database access
+	 * to throw a DBAccessError
+	 */
+	public static function disableBackend() {
+		global $wgLBFactoryConf;
+		self::$instance = new LBFactory_Fake( $wgLBFactoryConf );
+	}
+
+	/**
+	 * Resets the singleton for use if it's been disabled. Does nothing otherwise
+	 */
+	public static function enableBackend() {
+		if( self::$instance instanceof LBFactory_Fake )
+			self::$instance = null;
+	}
+
 	/**
 	 * Get an LBFactory instance
 	 */
@@ -35,6 +54,14 @@ abstract class LBFactory {
 		}
 	}
 
+	/**
+	 * Set the instance to be the given object
+	 */
+	static function setInstance( $instance ) {
+		self::destroyInstance();
+		self::$instance = $instance;
+	}
+
 	/**
 	 * Construct a factory based on a configuration array (typically from $wgLBFactoryConf)
 	 */
@@ -44,7 +71,7 @@ abstract class LBFactory {
 	 * Create a new load balancer object. The resulting object will be untracked,
 	 * not chronology-protected, and the caller is responsible for cleaning it up.
 	 *
-	 * @param string $wiki Wiki ID, or false for the current wiki
+	 * @param $wiki String: wiki ID, or false for the current wiki
 	 * @return LoadBalancer
 	 */
 	abstract function newMainLB( $wiki = false );
@@ -52,7 +79,7 @@ abstract class LBFactory {
 	/**
 	 * Get a cached (tracked) load balancer object.
 	 *
-	 * @param string $wiki Wiki ID, or false for the current wiki
+	 * @param $wiki String: wiki ID, or false for the current wiki
 	 * @return LoadBalancer
 	 */
 	abstract function getMainLB( $wiki = false );
@@ -62,16 +89,16 @@ abstract class LBFactory {
 	 * untracked, not chronology-protected, and the caller is responsible for
 	 * cleaning it up.
 	 *
-	 * @param string $cluster External storage cluster, or false for core
-	 * @param string $wiki Wiki ID, or false for the current wiki
+	 * @param $cluster String: external storage cluster, or false for core
+	 * @param $wiki String: wiki ID, or false for the current wiki
 	 */
 	abstract function newExternalLB( $cluster, $wiki = false );
 
 	/*
 	 * Get a cached (tracked) load balancer for external storage
 	 *
-	 * @param string $cluster External storage cluster, or false for core
-	 * @param string $wiki Wiki ID, or false for the current wiki
+	 * @param $cluster String: external storage cluster, or false for core
+	 * @param $wiki String: wiki ID, or false for the current wiki
 	 */
 	abstract function &getExternalLB( $cluster, $wiki = false );
 
@@ -197,6 +224,39 @@ class LBFactory_Simple extends LBFactory {
 	}
 }
 
+/**
+ * LBFactory class that throws an error on any attempt to use it.
+ * This will typically be done via wfGetDB().
+ * Call LBFactory::disableBackend() to start using this, and
+ * LBFactory::enableBackend() to return to normal behavior
+ */
+class LBFactory_Fake extends LBFactory {
+	function __construct( $conf ) {}
+
+	function newMainLB( $wiki = false) {
+		throw new DBAccessError;
+	}
+	function getMainLB( $wiki = false ) {
+		throw new DBAccessError;
+	}
+	function newExternalLB( $cluster, $wiki = false ) {
+		throw new DBAccessError;
+	}
+	function &getExternalLB( $cluster, $wiki = false ) {
+		throw new DBAccessError;
+	}
+	function forEachLB( $callback, $params = array() ) {}
+}
+
+/**
+ * Exception class for attempted DB access
+ */
+class DBAccessError extends MWException {
+	function __construct() {
+		parent::__construct( "Mediawiki tried to access the database via wfGetDB(). This is not allowed." );
+	}
+}
+
 /**
  * Class for ensuring a consistent ordering of events as seen by the user, despite replication.
  * Kind of like Hawking's [[Chronology Protection Agency]].
@@ -208,7 +268,7 @@ class ChronologyProtector {
 	/**
 	 * Initialise a LoadBalancer to give it appropriate chronology protection.
 	 *
-	 * @param LoadBalancer $lb
+	 * @param $lb LoadBalancer
 	 */
 	function initLB( $lb ) {
 		if ( $this->startupPos === null ) {
@@ -233,7 +293,7 @@ class ChronologyProtector {
 	 * Notify the ChronologyProtector that the LoadBalancer is about to shut
 	 * down. Saves replication positions.
 	 *
-	 * @param LoadBalancer $lb
+	 * @param $lb LoadBalancer
 	 */
 	function shutdownLB( $lb ) {
 		// Don't start a session, don't bother with non-replicated setups
-- 
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