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// Copyright 2014 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.
#ifndef CHROME_BROWSER_SYNC_FILE_SYSTEM_DRIVE_BACKEND_CALLBACK_HELPER_H_
#define CHROME_BROWSER_SYNC_FILE_SYSTEM_DRIVE_BACKEND_CALLBACK_HELPER_H_
#include "base/bind.h"
#include "base/location.h"
#include "base/logging.h"
#include "base/sequenced_task_runner.h"
#include "base/thread_task_runner_handle.h"
// TODO(tzik): Merge this file to media/base/bind_to_current_loop.h.
namespace sync_file_system {
namespace drive_backend {
namespace internal {
template <typename T>
typename base::enable_if<
base::internal::IsMoveOnlyType<T>::value,
base::internal::PassedWrapper<T> >::type
RebindForward(T& t) {
return base::Passed(&t);
}
template <typename T>
typename base::enable_if<
!base::internal::IsMoveOnlyType<T>::value,
T&>::type
RebindForward(T& t) {
return t;
}
template <typename T>
class CallbackHolder {
public:
CallbackHolder(const scoped_refptr<base::SequencedTaskRunner>& task_runner,
const tracked_objects::Location& from_here,
const base::Callback<T>& callback)
: task_runner_(task_runner),
from_here_(from_here),
callback_(new base::Callback<T>(callback)) {
DCHECK(task_runner_.get());
}
~CallbackHolder() {
base::Callback<T>* callback = callback_.release();
if (!task_runner_->DeleteSoon(from_here_, callback))
delete callback;
}
base::SequencedTaskRunner* task_runner() const { return task_runner_.get(); }
const tracked_objects::Location& from_here() const { return from_here_; }
const base::Callback<T>& callback() const { return *callback_; }
private:
scoped_refptr<base::SequencedTaskRunner> task_runner_;
const tracked_objects::Location from_here_;
scoped_ptr<base::Callback<T> > callback_;
DISALLOW_COPY_AND_ASSIGN(CallbackHolder);
};
template <typename>
struct RelayToTaskRunnerHelper;
template <typename... Args>
struct RelayToTaskRunnerHelper<void(Args...)> {
static void Run(CallbackHolder<void(Args...)>* holder, Args... args) {
holder->task_runner()->PostTask(
holder->from_here(),
base::Bind(holder->callback(),
RebindForward(args)...));
}
};
} // namespace internal
template <typename T>
base::Callback<T> RelayCallbackToTaskRunner(
const scoped_refptr<base::SequencedTaskRunner>& task_runner,
const tracked_objects::Location& from_here,
const base::Callback<T>& callback) {
DCHECK(task_runner->RunsTasksOnCurrentThread());
if (callback.is_null())
return base::Callback<T>();
return base::Bind(&internal::RelayToTaskRunnerHelper<T>::Run,
base::Owned(new internal::CallbackHolder<T>(
task_runner, from_here, callback)));
}
template <typename T>
base::Callback<T> RelayCallbackToCurrentThread(
const tracked_objects::Location& from_here,
const base::Callback<T>& callback) {
return RelayCallbackToTaskRunner(
base::ThreadTaskRunnerHandle::Get(),
from_here, callback);
}
} // namespace drive_backend
} // namespace sync_file_system
#endif // CHROME_BROWSER_SYNC_FILE_SYSTEM_DRIVE_BACKEND_CALLBACK_HELPER_H_
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