From 183851b06bd6c52f3cae5375f433da720d410447 Mon Sep 17 00:00:00 2001
From: Pierre Schmitz <pierre@archlinux.de>
Date: Wed, 11 Oct 2006 18:12:39 +0000
Subject: MediaWiki 1.7.1 wiederhergestellt

---
 includes/ExternalStoreDB.php | 150 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 150 insertions(+)
 create mode 100644 includes/ExternalStoreDB.php

(limited to 'includes/ExternalStoreDB.php')

diff --git a/includes/ExternalStoreDB.php b/includes/ExternalStoreDB.php
new file mode 100644
index 00000000..f610df80
--- /dev/null
+++ b/includes/ExternalStoreDB.php
@@ -0,0 +1,150 @@
+<?php
+/**
+ *
+ * @package MediaWiki
+ *
+ * DB accessable external objects
+ *
+ */
+require_once( 'LoadBalancer.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();
+
+class ExternalStoreDB {
+
+	/** @todo Document.*/
+	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];
+	}
+
+	/** @todo Document.*/
+	function &getSlave( $cluster ) {
+		$lb =& $this->getLoadBalancer( $cluster );
+		return $lb->getConnection( DB_SLAVE );
+	}
+
+	/** @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) {
+		$path = explode( '/', $url );
+		$cluster  = $path[2];
+		$id	  = $path[3];
+		if ( isset( $path[4] ) ) {
+			$itemID = $path[4];
+		} else {
+			$itemID = false;
+		}
+
+		$ret =& $this->fetchBlob( $cluster, $id, $itemID );
+
+		if ( $itemID !== false && $ret !== false ) {
+			return $ret->getItem( $itemID );
+		}
+		return $ret;
+	}
+
+	/**
+	 * 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";
+	}
+}
+?>
-- 
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