[FileBackend] Cleaned up resyncFiles() and added conservative resync option to FileBa...

Change-Id: I4fd96fda71fc1aba44104241a8329e95ba5cdda7

diff --git a/includes/filebackend/FileBackendMultiWrite.php b/includes/filebackend/FileBackendMultiWrite.php
index 17b060c..60c813b 100644 (file)
--- a/includes/filebackend/FileBackendMultiWrite.php
+++ b/includes/filebackend/FileBackendMultiWrite.php
@@ -75,6 +75,9 @@ class FileBackendMultiWrite extends FileBackend {
         *   - autoResync     : Automatically resync the clone backends to the master backend
         *                      when pre-operation sync checks fail. This should only be used
         *                      if the master backend is stable and not missing any files.
+        *                      Use "conservative" to limit resyncing to copying newer master
+        *                      backend files over older (or non-existing) clone backend files.
+        *                      Cases that cannot be handled will result in operation abortion.
         *   - noPushQuickOps : (hack) Only apply doQuickOperations() to the master backend.
         *   - noPushDirConts : (hack) Only apply directory functions to the master backend.
         *
@@ -86,7 +89,9 @@ class FileBackendMultiWrite extends FileBackend {
                $this->syncChecks = isset( $config['syncChecks'] )
                        ? $config['syncChecks']
                        : self::CHECK_SIZE;
-               $this->autoResync = !empty( $config['autoResync'] );
+               $this->autoResync = isset( $config['autoResync'] )
+                       ? $config['autoResync']
+                       : false;
                $this->noPushQuickOps = isset( $config['noPushQuickOps'] )
                        ? $config['noPushQuickOps']
                        : false;
@@ -304,11 +309,11 @@ class FileBackendMultiWrite extends FileBackend {
                $mBackend = $this->backends[$this->masterIndex];
                foreach ( $paths as $path ) {
                        $mPath = $this->substPaths( $path, $mBackend );
-                       $mSha1 = $mBackend->getFileSha1Base36( array( 'src' => $mPath ) );
-                       $mExist = $mBackend->fileExists( array( 'src' => $mPath ) );
-                       // Check if the master backend is available...
-                       if ( $mExist === null ) {
+                       $mSha1 = $mBackend->getFileSha1Base36( array( 'src' => $mPath, 'latest' => true ) );
+                       $mStat = $mBackend->getFileStat( array( 'src' => $mPath, 'latest' => true ) );
+                       if ( $mStat === null || ( $mSha1 !== false && !$mStat ) ) { // sanity
                                $status->fatal( 'backend-fail-internal', $this->name );
+                               continue; // file is not available on the master backend...
                        }
                        // Check of all clone backends agree with the master...
                        foreach ( $this->backends as $index => $cBackend ) {
@@ -316,15 +321,31 @@ class FileBackendMultiWrite extends FileBackend {
                                        continue; // master
                                }
                                $cPath = $this->substPaths( $path, $cBackend );
-                               $cSha1 = $cBackend->getFileSha1Base36( array( 'src' => $cPath ) );
+                               $cSha1 = $cBackend->getFileSha1Base36( array( 'src' => $cPath, 'latest' => true ) );
+                               $cStat = $cBackend->getFileStat( array( 'src' => $cPath, 'latest' => true ) );
+                               if ( $cStat === null || ( $cSha1 !== false && !$cStat ) ) { // sanity
+                                       $status->fatal( 'backend-fail-internal', $cBackend->getName() );
+                                       continue; // file is not available on the clone backend...
+                               }
                                if ( $mSha1 === $cSha1 ) {
                                        // already synced; nothing to do
-                               } elseif ( $mSha1 ) { // file is in master
-                                       $fsFile = $mBackend->getLocalReference( array( 'src' => $mPath ) );
+                               } elseif ( $mSha1 !== false ) { // file is in master
+                                       if ( $this->autoResync === 'conservative'
+                                               && $cStat && $cStat['mtime'] > $mStat['mtime'] )
+                                       {
+                                               $status->fatal( 'backend-fail-synced', $path );
+                                               continue; // don't rollback data
+                                       }
+                                       $fsFile = $mBackend->getLocalReference(
+                                               array( 'src' => $mPath, 'latest' => true ) );
                                        $status->merge( $cBackend->quickStore(
                                                array( 'src' => $fsFile->getPath(), 'dst' => $cPath )
                                        ) );
-                               } elseif ( $mExist === false ) { // file is not in master
+                               } elseif ( $mStat === false ) { // file is not in master
+                                       if ( $this->autoResync === 'conservative' ) {
+                                               $status->fatal( 'backend-fail-synced', $path );
+                                               continue; // don't delete data
+                                       }
                                        $status->merge( $cBackend->quickDelete( array( 'src' => $cPath ) ) );
                                }
                        }