1 files changed, 122 insertions, 20 deletions

diff --git a/includes/externalstore/ExternalStoreDB.php b/includes/externalstore/ExternalStoreDB.php
index 196e7f2c..46a89379 100644
--- a/includes/externalstore/ExternalStoreDB.php
+++ b/includes/externalstore/ExternalStoreDB.php
@@ -30,21 +30,13 @@
  */
 class ExternalStoreDB extends ExternalStoreMedium {
 	/**
-	 * The URL returned is of the form of the form DB://cluster/id
+	 * The provided URL is in the form of DB://cluster/id
 	 * or DB://cluster/id/itemid for concatened storage.
 	 *
 	 * @see ExternalStoreMedium::fetchFromURL()
 	 */
 	public function fetchFromURL( $url ) {
-		$path = explode( '/', $url );
-		$cluster = $path[2];
-		$id = $path[3];
-		if ( isset( $path[4] ) ) {
-			$itemID = $path[4];
-		} else {
-			$itemID = false;
-		}
-
+		list( $cluster, $id, $itemID ) = $this->parseURL( $url );
 		$ret =& $this->fetchBlob( $cluster, $id, $itemID );
 
 		if ( $itemID !== false && $ret !== false ) {
@@ -54,6 +46,41 @@ class ExternalStoreDB extends ExternalStoreMedium {
 	}
 
 	/**
+	 * Fetch data from given external store URLs.
+	 * The provided URLs are in the form of DB://cluster/id
+	 * or DB://cluster/id/itemid for concatened storage.
+	 *
+	 * @param array $urls An array of external store URLs
+	 * @return array A map from url to stored content. Failed results
+	 *     are not represented.
+	 */
+	public function batchFetchFromURLs( array $urls ) {
+		$batched = $inverseUrlMap = array();
+		foreach ( $urls as $url ) {
+			list( $cluster, $id, $itemID ) = $this->parseURL( $url );
+			$batched[$cluster][$id][] = $itemID;
+			// false $itemID gets cast to int, but should be ok
+			// since we do === from the $itemID in $batched
+			$inverseUrlMap[$cluster][$id][$itemID] = $url;
+		}
+		$ret = array();
+		foreach ( $batched as $cluster => $batchByCluster ) {
+			$res = $this->batchFetchBlobs( $cluster, $batchByCluster );
+			foreach ( $res as $id => $blob ) {
+				foreach ( $batchByCluster[$id] as $itemID ) {
+					$url = $inverseUrlMap[$cluster][$id][$itemID];
+					if ( $itemID === false ) {
+						$ret[$url] = $blob;
+					} else {
+						$ret[$url] = $blob->getItem( $itemID );
+					}
+				}
+			}
+		}
+		return $ret;
+	}
+
+	/**
 	 * @see ExternalStoreMedium::store()
 	 */
 	public function store( $cluster, $data ) {
@@ -64,7 +91,7 @@ class ExternalStoreDB extends ExternalStoreMedium {
 			__METHOD__ );
 		$id = $dbw->insertId();
 		if ( !$id ) {
-			throw new MWException( __METHOD__.': no insert ID' );
+			throw new MWException( __METHOD__ . ': no insert ID' );
 		}
 		if ( $dbw->getFlag( DBO_TRX ) ) {
 			$dbw->commit( __METHOD__ );
@@ -152,25 +179,31 @@ class ExternalStoreDB extends ExternalStoreMedium {
 		static $externalBlobCache = array();
 
 		$cacheID = ( $itemID === false ) ? "$cluster/$id" : "$cluster/$id/";
-		if( isset( $externalBlobCache[$cacheID] ) ) {
-			wfDebugLog( 'ExternalStoreDB-cache', "ExternalStoreDB::fetchBlob cache hit on $cacheID\n" );
+		if ( isset( $externalBlobCache[$cacheID] ) ) {
+			wfDebugLog( 'ExternalStoreDB-cache',
+				"ExternalStoreDB::fetchBlob cache hit on $cacheID\n" );
 			return $externalBlobCache[$cacheID];
 		}
 
-		wfDebugLog( 'ExternalStoreDB-cache', "ExternalStoreDB::fetchBlob cache miss on $cacheID\n" );
+		wfDebugLog( 'ExternalStoreDB-cache',
+			"ExternalStoreDB::fetchBlob cache miss on $cacheID\n" );
 
 		$dbr =& $this->getSlave( $cluster );
-		$ret = $dbr->selectField( $this->getTable( $dbr ), 'blob_text', array( 'blob_id' => $id ), __METHOD__ );
+		$ret = $dbr->selectField( $this->getTable( $dbr ),
+			'blob_text', array( 'blob_id' => $id ), __METHOD__ );
 		if ( $ret === false ) {
-			wfDebugLog( 'ExternalStoreDB', "ExternalStoreDB::fetchBlob master fallback on $cacheID\n" );
+			wfDebugLog( 'ExternalStoreDB',
+				"ExternalStoreDB::fetchBlob master fallback on $cacheID\n" );
 			// Try the master
 			$dbw =& $this->getMaster( $cluster );
-			$ret = $dbw->selectField( $this->getTable( $dbw ), 'blob_text', array( 'blob_id' => $id ), __METHOD__ );
-			if( $ret === false) {
-				wfDebugLog( 'ExternalStoreDB', "ExternalStoreDB::fetchBlob master failed to find $cacheID\n" );
+			$ret = $dbw->selectField( $this->getTable( $dbw ),
+				'blob_text', array( 'blob_id' => $id ), __METHOD__ );
+			if ( $ret === false ) {
+				wfDebugLog( 'ExternalStoreDB',
+					"ExternalStoreDB::fetchBlob master failed to find $cacheID\n" );
 			}
 		}
-		if( $itemID !== false && $ret !== false ) {
+		if ( $itemID !== false && $ret !== false ) {
 			// Unserialise object; caller extracts item
 			$ret = unserialize( $ret );
 		}
@@ -178,4 +211,73 @@ class ExternalStoreDB extends ExternalStoreMedium {
 		$externalBlobCache = array( $cacheID => &$ret );
 		return $ret;
 	}
+
+	/**
+	 * Fetch multiple blob items out of the database
+	 *
+	 * @param string $cluster A cluster name valid for use with LBFactory
+	 * @param array $ids A map from the blob_id's to look for to the requested itemIDs in the blobs
+	 * @return array A map from the blob_id's requested to their content.  Unlocated ids are not represented
+	 */
+	function batchFetchBlobs( $cluster, array $ids ) {
+		$dbr = $this->getSlave( $cluster );
+		$res = $dbr->select( $this->getTable( $dbr ),
+			array( 'blob_id', 'blob_text' ), array( 'blob_id' => array_keys( $ids ) ), __METHOD__ );
+		$ret = array();
+		if ( $res !== false ) {
+			$this->mergeBatchResult( $ret, $ids, $res );
+		}
+		if ( $ids ) {
+			wfDebugLog( __CLASS__, __METHOD__ .
+				" master fallback on '$cluster' for: " .
+				implode( ',', array_keys( $ids ) ) . "\n" );
+			// Try the master
+			$dbw = $this->getMaster( $cluster );
+			$res = $dbw->select( $this->getTable( $dbr ),
+				array( 'blob_id', 'blob_text' ),
+				array( 'blob_id' => array_keys( $ids ) ),
+				__METHOD__ );
+			if ( $res === false ) {
+				wfDebugLog( __CLASS__, __METHOD__ . " master failed on '$cluster'\n" );
+			} else {
+				$this->mergeBatchResult( $ret, $ids, $res );
+			}
+		}
+		if ( $ids ) {
+			wfDebugLog( __CLASS__, __METHOD__ .
+				" master on '$cluster' failed locating items: " .
+				implode( ',', array_keys( $ids ) ) . "\n" );
+		}
+		return $ret;
+	}
+
+	/**
+	 * Helper function for self::batchFetchBlobs for merging master/slave results
+	 * @param array &$ret Current self::batchFetchBlobs return value
+	 * @param array &$ids Map from blob_id to requested itemIDs
+	 * @param mixed $res DB result from DatabaseBase::select
+	 */
+	private function mergeBatchResult( array &$ret, array &$ids, $res ) {
+		foreach ( $res as $row ) {
+			$id = $row->blob_id;
+			$itemIDs = $ids[$id];
+			unset( $ids[$id] ); // to track if everything is found
+			if ( count( $itemIDs ) === 1 && reset( $itemIDs ) === false ) {
+				// single result stored per blob
+				$ret[$id] = $row->blob_text;
+			} else {
+				// multi result stored per blob
+				$ret[$id] = unserialize( $row->blob_text );
+			}
+		}
+	}
+
+	protected function parseURL( $url ) {
+		$path = explode( '/', $url );
+		return array(
+			$path[2], // cluster
+			$path[3], // id
+			isset( $path[4] ) ? $path[4] : false // itemID
+		);
+	}
 }