[fsp] Add throttling for number of opened files.

chrome/browser/chromeos/file_system_provider/throttled_file_system.cc

Index: chrome/browser/chromeos/file_system_provider/throttled_file_system.cc
diff --git a/chrome/browser/chromeos/file_system_provider/throttled_file_system.cc b/chrome/browser/chromeos/file_system_provider/throttled_file_system.cc
new file mode 100644
index 0000000000000000000000000000000000000000..de4f37f8223b3bedeba8ba5b70c30e14d65c2f30
--- /dev/null
+++ b/chrome/browser/chromeos/file_system_provider/throttled_file_system.cc
@@ -0,0 +1,218 @@
+// Copyright 2015 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 "chrome/browser/chromeos/file_system_provider/throttled_file_system.h"
+
+#include <limits>
+#include <vector>
+
+#include "base/files/file.h"
+#include "chrome/browser/chromeos/file_system_provider/queue.h"
+
+namespace chromeos {
+namespace file_system_provider {
+
+ThrottledFileSystem::ThrottledFileSystem(
+    scoped_ptr<ProvidedFileSystemInterface> file_system)
+    : file_system_(file_system.Pass()), weak_ptr_factory_(this) {
+  const int opened_files_limit =
+      file_system_->GetFileSystemInfo().opened_files_limit();
+  open_queue_.reset(opened_files_limit
+                        ? new Queue(static_cast<size_t>(opened_files_limit))
+                        : new Queue(std::numeric_limits<size_t>::max()));
+}
+
+ThrottledFileSystem::~ThrottledFileSystem() {
+}
+
+AbortCallback ThrottledFileSystem::RequestUnmount(
+    const storage::AsyncFileUtil::StatusCallback& callback) {
+  return file_system_->RequestUnmount(callback);
+}
+
+AbortCallback ThrottledFileSystem::GetMetadata(
+    const base::FilePath& entry_path,
+    MetadataFieldMask fields,
+    const GetMetadataCallback& callback) {
+  return file_system_->GetMetadata(entry_path, fields, callback);
+}
+
+AbortCallback ThrottledFileSystem::ReadDirectory(
+    const base::FilePath& directory_path,
+    const storage::AsyncFileUtil::ReadDirectoryCallback& callback) {
+  return file_system_->ReadDirectory(directory_path, callback);
+}
+
+AbortCallback ThrottledFileSystem::ReadFile(
+    int file_handle,
+    net::IOBuffer* buffer,
+    int64 offset,
+    int length,
+    const ReadChunkReceivedCallback& callback) {
+  return file_system_->ReadFile(file_handle, buffer, offset, length, callback);
+}
+
+AbortCallback ThrottledFileSystem::OpenFile(const base::FilePath& file_path,
+                                            OpenFileMode mode,
+                                            const OpenFileCallback& callback) {
+  const size_t task_token = open_queue_->NewToken();
+  return open_queue_->Enqueue(
+      task_token,
+      base::Bind(
+          &ProvidedFileSystemInterface::OpenFile,
+          base::Unretained(file_system_.get()),  // Outlives the queue.
+          file_path, mode,
+          base::Bind(&ThrottledFileSystem::OnOpenFileCompleted,
+                     weak_ptr_factory_.GetWeakPtr(), task_token, callback)));
+}
+
+AbortCallback ThrottledFileSystem::CloseFile(
+    int file_handle,
+    const storage::AsyncFileUtil::StatusCallback& callback) {
+  return file_system_->CloseFile(
+      file_handle,
+      base::Bind(&ThrottledFileSystem::OnCloseFileCompleted,
+                 weak_ptr_factory_.GetWeakPtr(), file_handle, callback));
+}
+
+AbortCallback ThrottledFileSystem::CreateDirectory(
+    const base::FilePath& directory_path,
+    bool recursive,
+    const storage::AsyncFileUtil::StatusCallback& callback) {
+  return file_system_->CreateDirectory(directory_path, recursive, callback);
+}
+
+AbortCallback ThrottledFileSystem::DeleteEntry(
+    const base::FilePath& entry_path,
+    bool recursive,
+    const storage::AsyncFileUtil::StatusCallback& callback) {
+  return file_system_->DeleteEntry(entry_path, recursive, callback);
+}
+
+AbortCallback ThrottledFileSystem::CreateFile(
+    const base::FilePath& file_path,
+    const storage::AsyncFileUtil::StatusCallback& callback) {
+  return file_system_->CreateFile(file_path, callback);
+}
+
+AbortCallback ThrottledFileSystem::CopyEntry(
+    const base::FilePath& source_path,
+    const base::FilePath& target_path,
+    const storage::AsyncFileUtil::StatusCallback& callback) {
+  return file_system_->CopyEntry(source_path, target_path, callback);
+}
+
+AbortCallback ThrottledFileSystem::WriteFile(
+    int file_handle,
+    net::IOBuffer* buffer,
+    int64 offset,
+    int length,
+    const storage::AsyncFileUtil::StatusCallback& callback) {
+  return file_system_->WriteFile(file_handle, buffer, offset, length, callback);
+}
+
+AbortCallback ThrottledFileSystem::MoveEntry(
+    const base::FilePath& source_path,
+    const base::FilePath& target_path,
+    const storage::AsyncFileUtil::StatusCallback& callback) {
+  return file_system_->MoveEntry(source_path, target_path, callback);
+}
+
+AbortCallback ThrottledFileSystem::Truncate(
+    const base::FilePath& file_path,
+    int64 length,
+    const storage::AsyncFileUtil::StatusCallback& callback) {
+  return file_system_->Truncate(file_path, length, callback);
+}
+
+AbortCallback ThrottledFileSystem::AddWatcher(
+    const GURL& origin,
+    const base::FilePath& entry_path,
+    bool recursive,
+    bool persistent,
+    const storage::AsyncFileUtil::StatusCallback& callback,
+    const storage::WatcherManager::NotificationCallback&
+        notification_callback) {
+  return file_system_->AddWatcher(origin, entry_path, recursive, persistent,
+                                  callback, notification_callback);
+}
+
+void ThrottledFileSystem::RemoveWatcher(
+    const GURL& origin,
+    const base::FilePath& entry_path,
+    bool recursive,
+    const storage::AsyncFileUtil::StatusCallback& callback) {
+  file_system_->RemoveWatcher(origin, entry_path, recursive, callback);
+}
+
+const ProvidedFileSystemInfo& ThrottledFileSystem::GetFileSystemInfo() const {
+  return file_system_->GetFileSystemInfo();
+}
+
+RequestManager* ThrottledFileSystem::GetRequestManager() {
+  return file_system_->GetRequestManager();
+}
+
+Watchers* ThrottledFileSystem::GetWatchers() {
+  return file_system_->GetWatchers();
+}
+
+void ThrottledFileSystem::AddObserver(ProvidedFileSystemObserver* observer) {
+  file_system_->AddObserver(observer);
+}
+
+void ThrottledFileSystem::RemoveObserver(ProvidedFileSystemObserver* observer) {
+  file_system_->RemoveObserver(observer);
+}
+
+void ThrottledFileSystem::Notify(
+    const base::FilePath& entry_path,
+    bool recursive,
+    storage::WatcherManager::ChangeType change_type,
+    scoped_ptr<ProvidedFileSystemObserver::Changes> changes,
+    const std::string& tag,
+    const storage::AsyncFileUtil::StatusCallback& callback) {
+  return file_system_->Notify(entry_path, recursive, change_type,
+                              changes.Pass(), tag, callback);
+}
+
+base::WeakPtr<ProvidedFileSystemInterface> ThrottledFileSystem::GetWeakPtr() {
+  return weak_ptr_factory_.GetWeakPtr();
+}
+
+void ThrottledFileSystem::OnOpenFileCompleted(int queue_token,
+                                              const OpenFileCallback& callback,
+                                              int file_handle,
+                                              base::File::Error result) {
+  open_queue_->Complete(queue_token);
+
+  // If the file is opened successfully then hold the queue token until the file
+  // is closed.
+  if (result == base::File::FILE_OK)
+    opened_files_[file_handle] = queue_token;
+  else
+    open_queue_->Remove(queue_token);
+
+  callback.Run(file_handle, result);
+}
+
+void ThrottledFileSystem::OnCloseFileCompleted(
+    int file_handle,
+    const storage::AsyncFileUtil::StatusCallback& callback,
+    base::File::Error result) {
+  // Closing is always final. Even if an error happened, the file is considered
+  // closed on the C++ side. Release the task from the queue, so other files
+  // which are enqueued can be opened.
+  const auto it = opened_files_.find(file_handle);
+  DCHECK(it != opened_files_.end());
+
+  const int queue_token = it->second;
+  open_queue_->Remove(queue_token);
+  opened_files_.erase(file_handle);
+
+  callback.Run(result);
+}
+
+}  // namespace file_system_provider
+}  // namespace chromeos