Adding file stat caching to avoid RTTs to high latency backends.

Also tweaked a few of the container cache functions a bit.

Change-Id: Ic91b8e04aa509410578b3a4dc232871c0c5561d0

diff --git a/includes/filerepo/backend/FileBackendStore.php b/includes/filerepo/backend/FileBackendStore.php
index b87a69f..fab62e5 100644 (file)
--- a/includes/filerepo/backend/FileBackendStore.php
+++ b/includes/filerepo/backend/FileBackendStore.php
@@ -86,6 +86,7 @@ abstract class FileBackendStore extends FileBackend {
                } else {
                        $status = $this->doCreateInternal( $params );
                        $this->clearCache( array( $params['dst'] ) );
+                       $this->deleteFileCache( $params['dst'] ); // persistent cache
                }
                wfProfileOut( __METHOD__ . '-' . $this->name );
                wfProfileOut( __METHOD__ );
@@ -117,6 +118,7 @@ abstract class FileBackendStore extends FileBackend {
                } else {
                        $status = $this->doStoreInternal( $params );
                        $this->clearCache( array( $params['dst'] ) );
+                       $this->deleteFileCache( $params['dst'] ); // persistent cache
                }
                wfProfileOut( __METHOD__ . '-' . $this->name );
                wfProfileOut( __METHOD__ );
@@ -145,6 +147,7 @@ abstract class FileBackendStore extends FileBackend {
                wfProfileIn( __METHOD__ . '-' . $this->name );
                $status = $this->doCopyInternal( $params );
                $this->clearCache( array( $params['dst'] ) );
+               $this->deleteFileCache( $params['dst'] ); // persistent cache
                wfProfileOut( __METHOD__ . '-' . $this->name );
                wfProfileOut( __METHOD__ );
                return $status;
@@ -171,6 +174,7 @@ abstract class FileBackendStore extends FileBackend {
                wfProfileIn( __METHOD__ . '-' . $this->name );
                $status = $this->doDeleteInternal( $params );
                $this->clearCache( array( $params['src'] ) );
+               $this->deleteFileCache( $params['src'] ); // persistent cache
                wfProfileOut( __METHOD__ . '-' . $this->name );
                wfProfileOut( __METHOD__ );
                return $status;
@@ -198,6 +202,8 @@ abstract class FileBackendStore extends FileBackend {
                wfProfileIn( __METHOD__ . '-' . $this->name );
                $status = $this->doMoveInternal( $params );
                $this->clearCache( array( $params['src'], $params['dst'] ) );
+               $this->deleteFileCache( $params['src'] ); // persistent cache
+               $this->deleteFileCache( $params['dst'] ); // persistent cache
                wfProfileOut( __METHOD__ . '-' . $this->name );
                wfProfileOut( __METHOD__ );
                return $status;
@@ -489,7 +495,10 @@ abstract class FileBackendStore extends FileBackend {
                        wfProfileOut( __METHOD__ );
                        return false; // invalid storage path
                }
-               $latest = !empty( $params['latest'] );
+               $latest = !empty( $params['latest'] ); // use latest data?
+               if ( !isset( $this->cache[$path]['stat'] ) ) {
+                       $this->primeFileCache( array( $path ) ); // check persistent cache
+               }
                if ( isset( $this->cache[$path]['stat'] ) ) {
                        // If we want the latest data, check that this cached
                        // value was in fact fetched with the latest available data.
@@ -506,9 +515,10 @@ abstract class FileBackendStore extends FileBackend {
                wfProfileOut( __METHOD__ . '-miss-' . $this->name );
                wfProfileOut( __METHOD__ . '-miss' );
                if ( is_array( $stat ) ) { // don't cache negatives
+                       $stat['latest'] = $latest;
                        $this->trimCache(); // limit memory
                        $this->cache[$path]['stat'] = $stat;
-                       $this->cache[$path]['stat']['latest'] = $latest;
+                       $this->setFileCache( $path, $stat ); // update persistent cache
                }
                wfProfileOut( __METHOD__ . '-' . $this->name );
                wfProfileOut( __METHOD__ );
@@ -875,7 +885,8 @@ abstract class FileBackendStore extends FileBackend {
                // Clear any file cache entries (after locks acquired)
                $this->clearCache();
 
-               // Load from the persistent container cache
+               // Load from the persistent file and container caches
+               $this->primeFileCache( $performOps );
                $this->primeContainerCache( $performOps );
 
                // Actually attempt the operation batch...
@@ -1199,7 +1210,7 @@ abstract class FileBackendStore extends FileBackend {
         * @return void
         */
        final protected function setContainerCache( $container, $val ) {
-               $this->memCache->set( $this->containerCacheKey( $container ), $val, 7*86400 );
+               $this->memCache->set( $this->containerCacheKey( $container ), $val, 14*86400 );
        }
 
        /**
@@ -1209,17 +1220,24 @@ abstract class FileBackendStore extends FileBackend {
         * @return void
         */
        final protected function deleteContainerCache( $container ) {
-               $this->memCache->delete( $this->containerCacheKey( $container ) );
+               for ( $attempts=1; $attempts <= 3; $attempts++ ) {
+                       if ( $this->memCache->delete( $this->containerCacheKey( $container ) ) ) {
+                               return; // done!
+                       }
+               }
+               trigger_error( "Unable to delete stat cache for container $container." );
        }
 
        /**
         * Do a batch lookup from cache for container stats for all containers
         * used in a list of container names, storage paths, or FileOp objects.
         *
-        * @param $items Array List of storage paths or FileOps
+        * @param $items Array
         * @return void
         */
        final protected function primeContainerCache( array $items ) {
+               wfProfileIn( __METHOD__ );
+               wfProfileIn( __METHOD__ . '-' . $this->name );
                $paths = array(); // list of storage paths
                $contNames = array(); // (cache key => resolved container name)
                // Get all the paths/containers from the items...
@@ -1250,6 +1268,8 @@ abstract class FileBackendStore extends FileBackend {
 
                // Populate the container process cache for the backend...
                $this->doPrimeContainerCache( array_filter( $contInfo, 'is_array' ) );
+               wfProfileOut( __METHOD__ . '-' . $this->name );
+               wfProfileOut( __METHOD__ );
        }
 
        /**
@@ -1261,6 +1281,82 @@ abstract class FileBackendStore extends FileBackend {
         * @return void
         */
        protected function doPrimeContainerCache( array $containerInfo ) {}
+
+       /**
+        * Get the cache key for a file path
+        *
+        * @param $path Storage path
+        * @return string
+        */
+       private function fileCacheKey( $path ) {
+               return wfMemcKey( 'backend', $this->getName(), 'file', sha1( $path ) );
+       }
+
+       /**
+        * Set the cached stat info for a file path
+        *
+        * @param $path Storage path
+        * @param $val mixed Information to cache
+        * @return void
+        */
+       final protected function setFileCache( $path, $val ) {
+               $this->memCache->set( $this->fileCacheKey( $path ), $val, 7*86400 );
+       }
+
+       /**
+        * Delete the cached stat info for a file path
+        *
+        * @param $path Storage path
+        * @return void
+        */
+       final protected function deleteFileCache( $path ) {
+               for ( $attempts=1; $attempts <= 3; $attempts++ ) {
+                       if ( $this->memCache->delete( $this->fileCacheKey( $path ) ) ) {
+                               return; // done!
+                       }
+               }
+               trigger_error( "Unable to delete stat cache for file $path." );
+       }
+
+       /**
+        * Do a batch lookup from cache for file stats for all paths
+        * used in a list of storage paths or FileOp objects.
+        *
+        * @param $items Array List of storage paths or FileOps
+        * @return void
+        */
+       final protected function primeFileCache( array $items ) {
+               wfProfileIn( __METHOD__ );
+               wfProfileIn( __METHOD__ . '-' . $this->name );
+               $paths = array(); // list of storage paths
+               $pathNames = array(); // (cache key => storage path)
+               // Get all the paths/containers from the items...
+               foreach ( $items as $item ) {
+                       if ( $item instanceof FileOp ) {
+                               $paths = array_merge( $paths, $item->storagePathsRead() );
+                               $paths = array_merge( $paths, $item->storagePathsChanged() );
+                       } elseif ( self::isStoragePath( $item ) ) {
+                               $paths[] = $item;
+                       }
+               }
+               // Get all the corresponding cache keys for paths...
+               foreach ( $paths as $path ) {
+                       list( $cont, $rel, $s ) = $this->resolveStoragePath( $path );
+                       if ( $rel !== null ) { // valid path for this backend
+                               $pathNames[$this->fileCacheKey( $path )] = $path;
+                       }
+               }
+               // Get all cache entries for these container cache keys...
+               $values = $this->memCache->getBatch( array_keys( $pathNames ) );
+               foreach ( $values as $cacheKey => $val ) {
+                       if ( is_array( $val ) ) {
+                               $this->trimCache(); // limit memory
+                               $this->cache[$pathNames[$cacheKey]]['stat'] = $val;
+                       }
+               }
+               wfProfileOut( __METHOD__ . '-' . $this->name );
+               wfProfileOut( __METHOD__ );
+       }
 }
 
 /**