blob: 8923429e91f499e93b6820e397d1829162397419 [file] [log] [blame]
// 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 <memory>
#include "base/bind.h"
#include "base/bind_helpers.h"
#include "base/callback.h"
#include "base/location.h"
#include "base/memory/ref_counted.h"
#include "base/memory/scoped_vector.h"
#include "base/task_runner.h"
#include "base/threading/thread_task_runner_handle.h"
// This is a helper utility for Bind()ing callbacks to a given TaskRunner.
// The typical use is when |a| (of class |A|) wants to hand a callback such as
// base::Bind(&A::AMethod, a) to |b|, but needs to ensure that when |b| executes
// the callback, it does so on a specific TaskRunner (for example, |a|'s current
// MessageLoop).
// Typical usage: request to be called back on the current thread:
// other->StartAsyncProcessAndCallMeBack(
// BindToTaskRunner(my_task_runner_, base::Bind(&MyClass::MyMethod, this)));
// Note that like base::Bind(), BindToTaskRunner() can't bind non-constant
// references, and that *unlike* base::Bind(), BindToTaskRunner() makes copies
// of its arguments, and thus can't be used with arrays. Note that the callback
// is always posted to the target TaskRunner.
// As a convenience, you can use BindToCurrentThread() to bind to the
// TaskRunner for the current thread (ie, base::ThreadTaskRunnerHandle::Get()).
namespace chromecast {
namespace bind_helpers {
template <typename T>
T& TrampolineForward(T& t) {
return t;
template <typename T, typename R>
base::internal::PassedWrapper<std::unique_ptr<T, R>> TrampolineForward(
std::unique_ptr<T, R>& p) {
return base::Passed(&p);
template <typename T>
base::internal::PassedWrapper<ScopedVector<T>> TrampolineForward(
ScopedVector<T>& p) {
return base::Passed(&p);
template <typename Sig>
struct BindToTaskRunnerTrampoline;
template <typename... Args>
struct BindToTaskRunnerTrampoline<void(Args...)> {
static void Run(const scoped_refptr<base::TaskRunner>& task_runner,
const base::Callback<void(Args...)>& cb,
Args... args) {
base::Bind(cb, TrampolineForward(args)...));
} // namespace bind_helpers
template <typename T>
base::Callback<T> BindToTaskRunner(
const scoped_refptr<base::TaskRunner>& task_runner,
const base::Callback<T>& cb) {
return base::Bind(&bind_helpers::BindToTaskRunnerTrampoline<T>::Run,
task_runner, cb);
template <typename T>
base::Callback<T> BindToCurrentThread(const base::Callback<T>& cb) {
return BindToTaskRunner(base::ThreadTaskRunnerHandle::Get(), cb);
} // namespace chromecast