[FileAPI] Remove Flush() on write completion on SandboxFileSystems

webkit/browser/fileapi/file_system_context.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "webkit/browser/fileapi/file_system_context.h"
 
 #include "base/bind.h"
 #include "base/single_thread_task_runner.h"
 #include "base/stl_util.h"
 #include "base/task_runner_util.h"
@@ skipping 461 matching lines @@
     return false;
 #if defined(OS_CHROMEOS)
   if (url.type() == kFileSystemTypeTemporary &&
       sandbox_backend_->enable_temporary_file_system_in_incognito()) {
     return true;
   }
 #endif
   return !is_incognito_ || !FileSystemContext::IsSandboxFileSystem(url.type());
 }
 
+bool FileSystemContext::ShouldFlushOnWriteCompletion(
+    FileSystemType type) const {
+  if (IsSandboxFileSystem(type)) {
+    // Disable Flush() for each write operation on SandboxFileSystems since it
+    // hurts the performance, assuming the FileSystems are stored in a local
+    // disk, we don't need to keep calling fsync() for it.

[kinuko, 2014/05/02 07:02:48]

Maybe... it'd be also better note that some non-sandbox filesystems that could
work on removable devices need flush to make sure its data is written out to the
disk?

[tzik, 2014/05/02 07:37:24]

Wrote some more about non-sandboxed filesystem.

+    return false;
+  }
+  return true;
+}
+
 void FileSystemContext::OpenPluginPrivateFileSystem(
     const GURL& origin_url,
     FileSystemType type,
     const std::string& filesystem_id,
     const std::string& plugin_id,
     OpenFileSystemMode mode,
     const StatusCallback& callback) {
   DCHECK(plugin_private_backend_);
   plugin_private_backend_->OpenPrivateFileSystem(
       origin_url, type, filesystem_id, plugin_id, mode, callback);
@@ skipping 115 matching lines @@
   } else if (parent != child) {
     bool result = parent.AppendRelativePath(child, &path);
     DCHECK(result);
   }
 
   operation_runner()->GetMetadata(
       url, base::Bind(&DidGetMetadataForResolveURL, path, callback, info));
 }
 
 }  // namespace fileapi