* Document a bit

[lhc/web/wiklou.git] / includes / ExternalStoreDB.php

diff --git a/includes/ExternalStoreDB.php b/includes/ExternalStoreDB.php
index beb4041..769c64d 100644 (file)
--- a/includes/ExternalStoreDB.php
+++ b/includes/ExternalStoreDB.php
@@ -1,15 +1,4 @@
 <?php
-/**
- *
- * @package MediaWiki
- *
- * DB accessable external objects
- *
- */
-require_once( 'LoadBalancer.php' );
-
-
-/** @package MediaWiki */
 
 /**
  * External database storage will use one (or more) separate connection pools
@@ -31,31 +20,58 @@ $wgExternalLoadBalancers = array();
 global $wgExternalBlobCache;
 $wgExternalBlobCache = array();
 
+/**
+ * DB accessable external objects
+ * @ingroup ExternalStorage
+ */
 class ExternalStoreDB {
+
+       function __construct( $params = array() ) {
+               $this->mParams = $params;
+       }
+
        /**
-        * Fetch data from given URL
-        * @param string $url An url
+        * Get a LoadBalancer for the specified cluster
+        *
+        * @param $cluster String: cluster name
+        * @return LoadBalancer object
         */
-
        function &getLoadBalancer( $cluster ) {
-               global $wgExternalServers, $wgExternalLoadBalancers;
-               if ( !array_key_exists( $cluster, $wgExternalLoadBalancers ) ) {
-                       $wgExternalLoadBalancers[$cluster] = LoadBalancer::newFromParams( $wgExternalServers[$cluster] );
-               }
-               $wgExternalLoadBalancers[$cluster]->allowLagged(true);
-               return $wgExternalLoadBalancers[$cluster];
+               $wiki = isset($this->mParams['wiki']) ? $this->mParams['wiki'] : false;
+               
+               return wfGetLBFactory()->getExternalLB( $cluster, $wiki );
        }
 
+       /**
+        * Get a slave database connection for the specified cluster
+        *
+        * @param $cluster String: cluster name
+        * @return DatabaseBase object
+        */
        function &getSlave( $cluster ) {
+               $wiki = isset($this->mParams['wiki']) ? $this->mParams['wiki'] : false;
                $lb =& $this->getLoadBalancer( $cluster );
-               return $lb->getConnection( DB_SLAVE );
+               return $lb->getConnection( DB_SLAVE, array(), $wiki );
        }
 
+       /**
+        * Get a master database connection for the specified cluster
+        *
+        * @param $cluster String: cluster name
+        * @return DatabaseBase object
+        */
        function &getMaster( $cluster ) {
+               $wiki = isset($this->mParams['wiki']) ? $this->mParams['wiki'] : false;
                $lb =& $this->getLoadBalancer( $cluster );
-               return $lb->getConnection( DB_MASTER );
+               return $lb->getConnection( DB_MASTER, array(), $wiki );
        }
 
+       /**
+        * Get the 'blobs' table name for this database
+        *
+        * @param $db DatabaseBase
+        * @return String: table name ('blobs' by default)
+        */
        function getTable( &$db ) {
                $table = $db->getLBInfo( 'blobs table' );
                if ( is_null( $table ) ) {
@@ -64,10 +80,11 @@ class ExternalStoreDB {
                return $table;
        }
 
-       function fetchFromURL($url) {
-               #
-               # URLs have the form DB://cluster/id or DB://cluster/id/itemid for concatenated storage
-               #
+       /**
+        * Fetch data from given URL
+        * @param $url String: an url of the form DB://cluster/id or DB://cluster/id/itemid for concatened storage.
+        */
+       function fetchFromURL( $url ) {
                $path = explode( '/', $url );
                $cluster  = $path[2];
                $id       = $path[3];
@@ -89,8 +106,11 @@ class ExternalStoreDB {
         * 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
-        * @access private
+        * @private
         */
        function &fetchBlob( $cluster, $id, $itemID ) {
                global $wgExternalBlobCache;
@@ -105,9 +125,13 @@ class ExternalStoreDB {
                $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 = $dbr->selectField( $this->getTable( $dbr ), 'blob_text', array( 'blob_id' => $id ) );
+                       $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
@@ -121,22 +145,23 @@ class ExternalStoreDB {
        /**
         * Insert a data item into a given cluster
         *
-        * @param string $cluster The cluster name
-        * @param string $data The data item
+        * @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 );
-
+               $dbw = $this->getMaster( $cluster );
                $id = $dbw->nextSequenceValue( 'blob_blob_id_seq' );
-               $dbw->insert( $this->getTable( $dbw ), array( 'blob_id' => $id, 'blob_text' => $data ), $fname );
+               $dbw->insert( $this->getTable( $dbw ), 
+                       array( 'blob_id' => $id, 'blob_text' => $data ), 
+                       __METHOD__ );
                $id = $dbw->insertId();
+               if ( !$id ) {
+                       throw new MWException( __METHOD__.': no insert ID' );
+               }
                if ( $dbw->getFlag( DBO_TRX ) ) {
-                       $dbw->immediateCommit();
+                       $dbw->commit();
                }
                return "DB://$cluster/$id";
        }
 }
-?>