From: Aaron Schulz <aschulz@wikimedia.org>
Date: Thu, 22 Feb 2018 08:27:14 +0000 (-0800)
Subject: Add ExternalStoreMedium::isReadOnly() method
X-Git-Tag: 1.31.0-rc.0~531^2
X-Git-Url: https://git.heureux-cyclage.org/?p=lhc%2Fweb%2Fwiklou.git;a=commitdiff_plain;h=656f60c15434afb69d60e511cfebf84fc4fbc2c2

Add ExternalStoreMedium::isReadOnly() method

Use this to abort out of store() calls early

Bug: T187942
Change-Id: I9334d36e8bc3e4589775471eee03be4f4a3119a3
---

diff --git a/includes/externalstore/ExternalStore.php b/includes/externalstore/ExternalStore.php
index 3beab29532..2ac6f7e82f 100644
--- a/includes/externalstore/ExternalStore.php
+++ b/includes/externalstore/ExternalStore.php
@@ -92,6 +92,7 @@ class ExternalStore {
 	 * @param array $urls The URLs of the text to get
 	 * @return array Map from url to its data.  Data is either string when found
 	 *     or false on failure.
+	 * @throws MWException
 	 */
 	public static function batchFetchFromURLs( array $urls ) {
 		$batches = [];
@@ -190,19 +191,25 @@ class ExternalStore {
 			if ( $store === false ) {
 				throw new MWException( "Invalid external storage protocol - $storeUrl" );
 			}
+
 			try {
-				$url = $store->store( $path, $data ); // Try to save the object
+				if ( $store->isReadOnly( $path ) ) {
+					$msg = 'read only';
+				} else {
+					$url = $store->store( $path, $data );
+					if ( strlen( $url ) ) {
+						return $url; // a store accepted the write; done!
+					}
+					$msg = 'operation failed';
+				}
 			} catch ( Exception $error ) {
-				$url = false;
-			}
-			if ( strlen( $url ) ) {
-				return $url; // Done!
-			} else {
-				unset( $tryStores[$index] ); // Don't try this one again!
-				$tryStores = array_values( $tryStores ); // Must have consecutive keys
-				wfDebugLog( 'ExternalStorage',
-					"Unable to store text to external storage $storeUrl" );
+				$msg = 'caught exception';
 			}
+
+			unset( $tryStores[$index] ); // Don't try this one again!
+			$tryStores = array_values( $tryStores ); // Must have consecutive keys
+			wfDebugLog( 'ExternalStorage',
+				"Unable to store text to external storage $storeUrl ($msg)" );
 		}
 		// All stores failed
 		if ( $error ) {
diff --git a/includes/externalstore/ExternalStoreDB.php b/includes/externalstore/ExternalStoreDB.php
index e5d36e10cb..b43bd210aa 100644
--- a/includes/externalstore/ExternalStoreDB.php
+++ b/includes/externalstore/ExternalStoreDB.php
@@ -103,6 +103,10 @@ class ExternalStoreDB extends ExternalStoreMedium {
 		return "DB://$location/$id";
 	}
 
+	public function isReadOnly( $location ) {
+		return ( $this->getLoadBalancer( $location )->getReadOnlyReason() !== false );
+	}
+
 	/**
 	 * Get a LoadBalancer for the specified cluster
 	 *
diff --git a/includes/externalstore/ExternalStoreHttp.php b/includes/externalstore/ExternalStoreHttp.php
index 8e1e49fa60..3d812c96ae 100644
--- a/includes/externalstore/ExternalStoreHttp.php
+++ b/includes/externalstore/ExternalStoreHttp.php
@@ -27,24 +27,15 @@
  * @ingroup ExternalStorage
  */
 class ExternalStoreHttp extends ExternalStoreMedium {
-	/**
-	 * @see ExternalStoreMedium::fetchFromURL()
-	 * @param string $url
-	 * @return string|bool
-	 * @throws MWException
-	 */
 	public function fetchFromURL( $url ) {
 		return Http::get( $url, [], __METHOD__ );
 	}
 
-	/**
-	 * @see ExternalStoreMedium::store()
-	 * @param string $cluster
-	 * @param string $data
-	 * @return string|bool
-	 * @throws MWException
-	 */
-	public function store( $cluster, $data ) {
+	public function store( $location, $data ) {
 		throw new MWException( "ExternalStoreHttp is read-only and does not support store()." );
 	}
+
+	public function isReadOnly( $location ) {
+		return true;
+	}
 }
diff --git a/includes/externalstore/ExternalStoreMedium.php b/includes/externalstore/ExternalStoreMedium.php
index 6cfa08389e..f1eaa93b9f 100644
--- a/includes/externalstore/ExternalStoreMedium.php
+++ b/includes/externalstore/ExternalStoreMedium.php
@@ -76,4 +76,15 @@ abstract class ExternalStoreMedium {
 	 * @throws MWException
 	 */
 	abstract public function store( $location, $data );
+
+	/**
+	 * Check if a given location is read-only
+	 *
+	 * @param string $location The location name
+	 * @return bool Whether this location is read-only
+	 * @since 1.31
+	 */
+	public function isReadOnly( $location ) {
+		return false;
+	}
 }
diff --git a/includes/externalstore/ExternalStoreMwstore.php b/includes/externalstore/ExternalStoreMwstore.php
index 5395f56274..0c6d022fc5 100644
--- a/includes/externalstore/ExternalStoreMwstore.php
+++ b/includes/externalstore/ExternalStoreMwstore.php
@@ -73,13 +73,6 @@ class ExternalStoreMwstore extends ExternalStoreMedium {
 		return $blobs;
 	}
 
-	/**
-	 * @see ExternalStoreMedium::store()
-	 * @param string $backend
-	 * @param string $data
-	 * @return string|bool
-	 * @throws MWException
-	 */
 	public function store( $backend, $data ) {
 		$be = FileBackendGroup::singleton()->get( $backend );
 		if ( $be instanceof FileBackend ) {
@@ -103,4 +96,10 @@ class ExternalStoreMwstore extends ExternalStoreMedium {
 
 		return false;
 	}
+
+	public function isReadOnly( $backend ) {
+		$be = FileBackendGroup::singleton()->get( $backend );
+
+		return $be ? $be->isReadOnly() : false;
+	}
 }