X-Git-Url: https://git.heureux-cyclage.org/?a=blobdiff_plain;f=includes%2FExternalStoreDB.php;h=549412d18bf1ad35c1dc1b8c0744ec51a4eaec6c;hb=461a770a6fa5b43107d204c1230721751875236b;hp=9d12dc61a77321c64fa7941b8bebfc0d1dc060eb;hpb=aa8d2db46d4cdf8b388c057e72fa388727fecc9e;p=lhc%2Fweb%2Fwiklou.git

diff --git a/includes/ExternalStoreDB.php b/includes/ExternalStoreDB.php
index 9d12dc61a7..549412d18b 100644
--- a/includes/ExternalStoreDB.php
+++ b/includes/ExternalStoreDB.php
@@ -1,37 +1,137 @@
 <?php
+
 /**
- * 
- * @package MediaWiki
+ * External database storage will use one (or more) separate connection pools
+ * from what the main wiki uses. If we load many revisions, such as when doing
+ * bulk backups or maintenance, we want to keep them around over the lifetime
+ * of the script.
  *
+ * Associative array of LoadBalancer objects, indexed by cluster name.
+ */
+global $wgExternalLoadBalancers;
+$wgExternalLoadBalancers = array();
+
+/**
+ * One-step cache variable to hold base blobs; operations that
+ * pull multiple revisions may often pull multiple times from
+ * the same blob. By keeping the last-used one open, we avoid
+ * redundant unserialization and decompression overhead.
+ */
+global $wgExternalBlobCache;
+$wgExternalBlobCache = array();
+
+/**
  * DB accessable external objects
- *
+ * @ingroup ExternalStorage
  */
-require_once( 'LoadBalancer.php' ); 
+class ExternalStoreDB {
 
+	/** @todo Document.*/
+	function &getLoadBalancer( $cluster ) {
+		return wfGetLBFactory()->getExternalLB( $cluster );
+	}
 
+	/** @todo Document.*/
+	function &getSlave( $cluster ) {
+		$lb =& $this->getLoadBalancer( $cluster );
+		return $lb->getConnection( DB_SLAVE );
+	}
 
-class ExternalStoreDB {
-	/* Fetch data from given URL */
+	/** @todo Document.*/
+	function &getMaster( $cluster ) {
+		$lb =& $this->getLoadBalancer( $cluster );
+		return $lb->getConnection( DB_MASTER );
+	}
+
+	/** @todo Document.*/
+	function getTable( &$db ) {
+		$table = $db->getLBInfo( 'blobs table' );
+		if ( is_null( $table ) ) {
+			$table = 'blobs';
+		}
+		return $table;
+	}
+
+	/**
+	 * Fetch data from given URL
+	 * @param string $url An url of the form DB://cluster/id or DB://cluster/id/itemid for concatened storage.
+	 */
 	function fetchFromURL($url) {
-		global $wgExternalServers;
-		#
-		# URLs have the form DB://cluster/id, e.g.
-		# DB://cluster1/3298247
-		#
 		$path = explode( '/', $url );
 		$cluster  = $path[2];
 		$id	  = $path[3];
+		if ( isset( $path[4] ) ) {
+			$itemID = $path[4];
+		} else {
+			$itemID = false;
+		}
 
-		$lb = LoadBalancer::NewFromParams( $wgExternalServers[$cluster] );
-		$db = $lb->getConnection( DB_SLAVE );
+		$ret =& $this->fetchBlob( $cluster, $id, $itemID );
 
-		$ret = $db->selectField( 'blobs', 'blob_text', array( 'blob_id' => $id ) ); 
-		
+		if ( $itemID !== false && $ret !== false ) {
+			return $ret->getItem( $itemID );
+		}
 		return $ret;
 	}
 
-	/* XXX: may require other methods, for store, delete, 
-	 * whatever, for initial ext storage  
+	/**
+	 * Fetch a blob item out of the database; a cache of the last-loaded
+	 * blob will be kept so that multiple loads out of a multi-item blob
+	 * can avoid redundant database access and decompression.
+	 * @param $cluster
+	 * @param $id
+	 * @param $itemID
+	 * @return mixed
+	 * @private
 	 */
+	function &fetchBlob( $cluster, $id, $itemID ) {
+		global $wgExternalBlobCache;
+		$cacheID = ( $itemID === false ) ? "$cluster/$id" : "$cluster/$id/";
+		if( isset( $wgExternalBlobCache[$cacheID] ) ) {
+			wfDebug( "ExternalStoreDB::fetchBlob cache hit on $cacheID\n" );
+			return $wgExternalBlobCache[$cacheID];
+		}
+
+		wfDebug( "ExternalStoreDB::fetchBlob cache miss on $cacheID\n" );
+
+		$dbr =& $this->getSlave( $cluster );
+		$ret = $dbr->selectField( $this->getTable( $dbr ), 'blob_text', array( 'blob_id' => $id ) );
+		if ( $ret === false ) {
+			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 ) );
+			if( $ret === false) {
+				wfDebugLog( 'ExternalStoreDB', "ExternalStoreDB::fetchBlob master failed to find $cacheID\n" );
+			}
+		}
+		if( $itemID !== false && $ret !== false ) {
+			// Unserialise object; caller extracts item
+			$ret = unserialize( $ret );
+		}
+
+		$wgExternalBlobCache = array( $cacheID => &$ret );
+		return $ret;
+	}
+
+	/**
+	 * Insert a data item into a given cluster
+	 *
+	 * @param $cluster String: the cluster name
+	 * @param $data String: the data item
+	 * @return string URL
+	 */
+	function store( $cluster, $data ) {
+		$fname = 'ExternalStoreDB::store';
+
+		$dbw =& $this->getMaster( $cluster );
+
+		$id = $dbw->nextSequenceValue( 'blob_blob_id_seq' );
+		$dbw->insert( $this->getTable( $dbw ), array( 'blob_id' => $id, 'blob_text' => $data ), $fname );
+		$id = $dbw->insertId();
+		if ( $dbw->getFlag( DBO_TRX ) ) {
+			$dbw->immediateCommit();
+		}
+		return "DB://$cluster/$id";
+	}
 }
-?>