SyncFS: Introduce SyncFileSystemBackend

webkit/browser/fileapi/syncable/sync_file_system_backend.cc

+// Copyright 2013 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/syncable/sync_file_system_backend.h"
+
+#include "base/logging.h"
+#include "base/metrics/histogram.h"
+#include "webkit/browser/fileapi/async_file_util_adapter.h"
+#include "webkit/browser/fileapi/file_system_context.h"
+#include "webkit/browser/fileapi/obfuscated_file_util.h"
+#include "webkit/browser/fileapi/sandbox_quota_observer.h"
+#include "webkit/browser/fileapi/syncable/syncable_file_system_operation.h"
+#include "webkit/browser/fileapi/syncable/syncable_file_system_util.h"
+#include "webkit/common/fileapi/file_system_util.h"
+
+namespace sync_file_system {
+
+SyncFileSystemBackend::SyncFileSystemBackend(
+    const fileapi::FileSystemOptions& file_system_options)
+    : SandboxFileSystemBackend(NULL, file_system_options) {
+}
+
+SyncFileSystemBackend::~SyncFileSystemBackend() {
+}
+
+bool SyncFileSystemBackend::CanHandleType(
+    fileapi::FileSystemType type) const {
+  return type == fileapi::kFileSystemTypeSyncable ||
+         type == fileapi::kFileSystemTypeSyncableForInternalSync;
+}
+
+void SyncFileSystemBackend::Initialize(
+    const fileapi::FileSystemContext* context) {
+  DCHECK(context);
+  DCHECK(!sandbox_context());
+  set_sandbox_context(context->sandbox_context());
+  // Set quota observers.
+  if (sandbox_context()->is_usage_tracking_enabled()) {
+    set_update_observers(update_observers()->AddObserver(
+        sandbox_context()->quota_observer(),
+        sandbox_context()->file_task_runner()));
+    set_access_observers(access_observers()->AddObserver(
+        sandbox_context()->quota_observer(), NULL));

[kinuko, 2013/07/24 06:18:30]

When do we use the parent class's update_observers?  Why do we need to update
the parent class's observers here?  Can we just call
SandboxFileSystemBackend::Initialize instead?

This SandboxFSBackend - SyncFSBackend's inheritance relationship is not really
great right now, I feel a little more time should be spent to think about what
will make this separation clearer.

[nhiroki, 2013/07/24 10:22:58]

Right, I realized we don't need to treat the those observers in Add*Observer()
and Get*Observers(). Removed them.
As I mentioned on offine chat, this is because I wanted to avoid calling
MaybePrepopulateDatabase() twice from SandboxFSBackend::Initialize() and
SyncFSBackend::Initialize(). Moved the function into SandboxContext so that we
can call SandboxFSB::Initialize() here.
I think the situation is somewhat getting better by this latest change. WDYT?

+    syncable_update_observers_ = syncable_update_observers_.AddObserver(
+        sandbox_context()->quota_observer(),
+        sandbox_context()->file_task_runner());
+  }
+}
+
+void SyncFileSystemBackend::OpenFileSystem(
+    const GURL& origin_url,
+    fileapi::FileSystemType type,
+    fileapi::OpenFileSystemMode mode,
+    const OpenFileSystemCallback& callback) {
+  // TODO(nhiroki): Implement SyncFileSystem's own OpenFileSystem.
+  SandboxFileSystemBackend::OpenFileSystem(origin_url, type, mode, callback);

[kinuko, 2013/07/24 06:18:30]

What's your plan to proceed? I'm slightly not sure why this is separated out.

[nhiroki, 2013/07/24 10:22:58]

Let me explain... it was my plan that the following CL extracts common routine
from SandboxFS:OpenFileSystem into somewhere and adds start-up routine for the
sync service which could be called if the service hasn't started (i.e. called
via resolveLocalFileSystemURL()).

Anyway, added OpenFileSystemInternal() which does the common routine for both
backends.

+}
+
+fileapi::FileSystemFileUtil* SyncFileSystemBackend::GetFileUtil(
+    fileapi::FileSystemType type) {
+  DCHECK(sandbox_context());
+  return sandbox_context()->sync_file_util();
+}
+
+fileapi::AsyncFileUtil* SyncFileSystemBackend::GetAsyncFileUtil(
+    fileapi::FileSystemType type) {
+  DCHECK(sandbox_context());
+  return sandbox_context()->file_util();
+}
+
+fileapi::FileSystemOperation*
+SyncFileSystemBackend::CreateFileSystemOperation(
+    const fileapi::FileSystemURL& url,
+    fileapi::FileSystemContext* context,
+    base::PlatformFileError* error_code) const {
+  if (!IsAccessValid(url)) {
+    *error_code = base::PLATFORM_FILE_ERROR_SECURITY;
+    return NULL;
+  }
+
+  if (url.type() == fileapi::kFileSystemTypeSyncableForInternalSync) {
+    return SandboxFileSystemBackend::CreateFileSystemOperation(
+        url, context, error_code);
+  }
+
+  scoped_ptr<fileapi::FileSystemOperationContext> operation_context(
+      new fileapi::FileSystemOperationContext(context));
+  operation_context->set_update_observers(syncable_update_observers_);
+  operation_context->set_change_observers(syncable_change_observers_);
+
+  return new SyncableFileSystemOperation(
+      url, context, operation_context.Pass());
+}
+
+void SyncFileSystemBackend::AddFileUpdateObserver(
+    fileapi::FileSystemType type,
+    fileapi::FileUpdateObserver* observer,
+    base::SequencedTaskRunner* task_runner) {
+  DCHECK(CanHandleType(type));
+  if (type == fileapi::kFileSystemTypeSyncableForInternalSync) {
+    SandboxFileSystemBackend::AddFileUpdateObserver(
+        type, observer, task_runner);
+    return;
+  }
+  fileapi::UpdateObserverList* list = &syncable_update_observers_;
+  *list = list->AddObserver(observer, task_runner);
+}
+
+void SyncFileSystemBackend::AddFileChangeObserver(
+    fileapi::FileSystemType type,
+    fileapi::FileChangeObserver* observer,
+    base::SequencedTaskRunner* task_runner) {
+  DCHECK(CanHandleType(type));
+  if (type == fileapi::kFileSystemTypeSyncableForInternalSync) {
+    SandboxFileSystemBackend::AddFileChangeObserver(
+        type, observer, task_runner);
+    return;
+  }
+  fileapi::ChangeObserverList* list = &syncable_change_observers_;
+  *list = list->AddObserver(observer, task_runner);
+}
+
+const fileapi::UpdateObserverList* SyncFileSystemBackend::GetUpdateObservers(
+    fileapi::FileSystemType type) const {
+  DCHECK(CanHandleType(type));
+  if (type == fileapi::kFileSystemTypeSyncableForInternalSync)
+    return update_observers();
+  return &syncable_update_observers_;
+}
+
+const fileapi::ChangeObserverList* SyncFileSystemBackend::GetChangeObservers(
+    fileapi::FileSystemType type) const {
+  DCHECK(CanHandleType(type));
+  if (type == fileapi::kFileSystemTypeSyncableForInternalSync)
+    return change_observers();
+  return &syncable_change_observers_;
+}
+
+// static
+SyncFileSystemBackend* SyncFileSystemBackend::GetBackend(
+    const fileapi::FileSystemContext* file_system_context) {
+  return static_cast<SyncFileSystemBackend*>(
+      file_system_context->GetFileSystemBackend(
+          fileapi::kFileSystemTypeSyncable));
+}
+
+}  // namespace sync_file_system