| // 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. |
| |
| #ifndef BASE_TASK_RUNNER_UTIL_H_ |
| #define BASE_TASK_RUNNER_UTIL_H_ |
| |
| #include "base/bind.h" |
| #include "base/bind_helpers.h" |
| #include "base/callback_internal.h" |
| #include "base/logging.h" |
| #include "base/task_runner.h" |
| |
| namespace base { |
| |
| namespace internal { |
| |
| // Adapts a function that produces a result via a return value to |
| // one that returns via an output parameter. |
| template <typename ReturnType> |
| void ReturnAsParamAdapter(const Callback<ReturnType(void)>& func, |
| ReturnType* result) { |
| *result = func.Run(); |
| } |
| |
| // Adapts a T* result to a callblack that expects a T. |
| template <typename TaskReturnType, typename ReplyArgType> |
| void ReplyAdapter(const Callback<void(ReplyArgType)>& callback, |
| TaskReturnType* result) { |
| // TODO(ajwong): Remove this conditional and add a DCHECK to enforce that |
| // |reply| must be non-null in PostTaskAndReplyWithResult() below after |
| // current code that relies on this API softness has been removed. |
| // http://crbug.com/162712 |
| if (!callback.is_null()) |
| callback.Run(CallbackForward(*result)); |
| } |
| |
| } // namespace internal |
| |
| // When you have these methods |
| // |
| // R DoWorkAndReturn(); |
| // void Callback(const R& result); |
| // |
| // and want to call them in a PostTaskAndReply kind of fashion where the |
| // result of DoWorkAndReturn is passed to the Callback, you can use |
| // PostTaskAndReplyWithResult as in this example: |
| // |
| // PostTaskAndReplyWithResult( |
| // target_thread_.task_runner(), |
| // FROM_HERE, |
| // Bind(&DoWorkAndReturn), |
| // Bind(&Callback)); |
| template <typename TaskReturnType, typename ReplyArgType> |
| bool PostTaskAndReplyWithResult( |
| TaskRunner* task_runner, |
| const tracked_objects::Location& from_here, |
| const Callback<TaskReturnType(void)>& task, |
| const Callback<void(ReplyArgType)>& reply) { |
| TaskReturnType* result = new TaskReturnType(); |
| return task_runner->PostTaskAndReply( |
| from_here, |
| base::Bind(&internal::ReturnAsParamAdapter<TaskReturnType>, task, |
| result), |
| base::Bind(&internal::ReplyAdapter<TaskReturnType, ReplyArgType>, reply, |
| base::Owned(result))); |
| } |
| |
| } // namespace base |
| |
| #endif // BASE_TASK_RUNNER_UTIL_H_ |