1 files changed, 50 insertions, 23 deletions

diff --git a/includes/BacklinkCache.php b/includes/BacklinkCache.php
index a7bcd858..53f92dd9 100644
--- a/includes/BacklinkCache.php
+++ b/includes/BacklinkCache.php
@@ -1,10 +1,9 @@
 <?php
-
 /**
  * Class for fetching backlink lists, approximate backlink counts and partitions.
  * Instances of this class should typically be fetched with $title->getBacklinkCache().
  *
- * Ideally you should only get your backlinks from here when you think there is some 
+ * Ideally you should only get your backlinks from here when you think there is some
  * advantage in caching them. Otherwise it's just a waste of memory.
  */
 class BacklinkCache {
@@ -47,44 +46,53 @@ class BacklinkCache {
 
 	/**
 	 * Get the backlinks for a given table. Cached in process memory only.
-	 * @param string $table
+	 * @param $table String
+	 * @param $startId Integer or false
+	 * @param $endId Integer or false
 	 * @return TitleArray
 	 */
 	public function getLinks( $table, $startId = false, $endId = false ) {
 		wfProfileIn( __METHOD__ );
 
+		$fromField = $this->getPrefix( $table ) . '_from';
+
 		if ( $startId || $endId ) {
 			// Partial range, not cached
-			wfDebug( __METHOD__.": from DB (uncacheable range)\n" );
+			wfDebug( __METHOD__ . ": from DB (uncacheable range)\n" );
 			$conds = $this->getConditions( $table );
 			// Use the from field in the condition rather than the joined page_id,
 			// because databases are stupid and don't necessarily propagate indexes.
-			$fromField = $this->getPrefix( $table ) . '_from';
 			if ( $startId ) {
 				$conds[] = "$fromField >= " . intval( $startId );
 			}
 			if ( $endId ) {
 				$conds[] = "$fromField <= " . intval( $endId );
 			}
-			$res = $this->getDB()->select( 
+			$res = $this->getDB()->select(
 				array( $table, 'page' ),
-				array( 'page_namespace', 'page_title', 'page_id'),
+				array( 'page_namespace', 'page_title', 'page_id' ),
 				$conds,
 				__METHOD__,
-				array('STRAIGHT_JOIN') );
+				array(
+					'STRAIGHT_JOIN',
+					'ORDER BY' => $fromField
+				) );
 			$ta = TitleArray::newFromResult( $res );
 			wfProfileOut( __METHOD__ );
 			return $ta;
 		}
 
 		if ( !isset( $this->fullResultCache[$table] ) ) {
-			wfDebug( __METHOD__.": from DB\n" );
-			$res = $this->getDB()->select( 
+			wfDebug( __METHOD__ . ": from DB\n" );
+			$res = $this->getDB()->select(
 				array( $table, 'page' ),
 				array( 'page_namespace', 'page_title', 'page_id' ),
 				$this->getConditions( $table ),
 				__METHOD__,
-				array('STRAIGHT_JOIN') );
+				array(
+					'STRAIGHT_JOIN',
+					'ORDER BY' => $fromField,
+				) );
 			$this->fullResultCache[$table] = $res;
 		}
 		$ta = TitleArray::newFromResult( $this->fullResultCache[$table] );
@@ -103,6 +111,7 @@ class BacklinkCache {
 			'templatelinks' => 'tl',
 			'redirect' => 'rd',
 		);
+
 		if ( isset( $prefixes[$table] ) ) {
 			return $prefixes[$table];
 		} else {
@@ -115,6 +124,7 @@ class BacklinkCache {
 	 */
 	protected function getConditions( $table ) {
 		$prefix = $this->getPrefix( $table );
+
 		switch ( $table ) {
 			case 'pagelinks':
 			case 'templatelinks':
@@ -126,13 +136,13 @@ class BacklinkCache {
 				);
 				break;
 			case 'imagelinks':
-				$conds = array( 
+				$conds = array(
 					'il_to' => $this->title->getDBkey(),
 					'page_id=il_from'
 				);
 				break;
 			case 'categorylinks':
-				$conds = array( 
+				$conds = array(
 					'cl_to' => $this->title->getDBkey(),
 					'page_id=cl_from',
 				);
@@ -150,10 +160,12 @@ class BacklinkCache {
 		if ( isset( $this->fullResultCache[$table] ) ) {
 			return $this->fullResultCache[$table]->numRows();
 		}
+
 		if ( isset( $this->partitionCache[$table] ) ) {
 			$entry = reset( $this->partitionCache[$table] );
 			return $entry['numRows'];
 		}
+
 		$titleArray = $this->getLinks( $table );
 		return $titleArray->count();
 	}
@@ -163,33 +175,40 @@ class BacklinkCache {
 	 * Returns an array giving the start and end of each range. The first batch has
 	 * a start of false, and the last batch has an end of false.
 	 *
-	 * @param string $table The links table name
-	 * @param integer $batchSize
-	 * @return array
+	 * @param $table String: the links table name
+	 * @param $batchSize Integer
+	 * @return Array
 	 */
 	public function partition( $table, $batchSize ) {
 		// Try cache
 		if ( isset( $this->partitionCache[$table][$batchSize] ) ) {
-			wfDebug( __METHOD__.": got from partition cache\n" );
+			wfDebug( __METHOD__ . ": got from partition cache\n" );
 			return $this->partitionCache[$table][$batchSize]['batches'];
 		}
+
 		$this->partitionCache[$table][$batchSize] = false;
 		$cacheEntry =& $this->partitionCache[$table][$batchSize];
 
 		// Try full result cache
 		if ( isset( $this->fullResultCache[$table] ) ) {
 			$cacheEntry = $this->partitionResult( $this->fullResultCache[$table], $batchSize );
-			wfDebug( __METHOD__.": got from full result cache\n" );
+			wfDebug( __METHOD__ . ": got from full result cache\n" );
 			return $cacheEntry['batches'];
 		}
+
 		// Try memcached
 		global $wgMemc;
-		$memcKey = wfMemcKey( 'backlinks', md5( $this->title->getPrefixedDBkey() ), 
-			$table, $batchSize );
+		$memcKey = wfMemcKey(
+			'backlinks',
+			md5( $this->title->getPrefixedDBkey() ),
+			$table,
+			$batchSize
+		);
 		$memcValue = $wgMemc->get( $memcKey );
+
 		if ( is_array( $memcValue ) ) {
 			$cacheEntry = $memcValue;
-			wfDebug( __METHOD__.": got from memcached $memcKey\n" );
+			wfDebug( __METHOD__ . ": got from memcached $memcKey\n" );
 			return $cacheEntry['batches'];
 		}
 		// Fetch from database
@@ -197,17 +216,18 @@ class BacklinkCache {
 		$cacheEntry = $this->partitionResult( $this->fullResultCache[$table], $batchSize );
 		// Save to memcached
 		$wgMemc->set( $memcKey, $cacheEntry, self::CACHE_EXPIRY );
-		wfDebug( __METHOD__.": got from database\n" );
+		wfDebug( __METHOD__ . ": got from database\n" );
 		return $cacheEntry['batches'];
 	}
 
-	/** 
+	/**
 	 * Partition a DB result with backlinks in it into batches
 	 */
 	protected function partitionResult( $res, $batchSize ) {
 		$batches = array();
 		$numRows = $res->numRows();
 		$numBatches = ceil( $numRows / $batchSize );
+
 		for ( $i = 0; $i < $numBatches; $i++ ) {
 			if ( $i == 0  ) {
 				$start = false;
@@ -217,6 +237,7 @@ class BacklinkCache {
 				$row = $res->fetchObject();
 				$start = $row->page_id;
 			}
+
 			if ( $i == $numBatches - 1 ) {
 				$end = false;
 			} else {
@@ -225,6 +246,12 @@ class BacklinkCache {
 				$row = $res->fetchObject();
 				$end = $row->page_id - 1;
 			}
+
+			# Sanity check order
+			if ( $start && $end && $start > $end ) {
+				throw new MWException( __METHOD__ . ': Internal error: query result out of order' );
+			}
+
 			$batches[] = array( $start, $end );
 		}
 		return array( 'numRows' => $numRows, 'batches' => $batches );