| /* |
| * Copyright 2015 Google Inc. All Rights Reserved. |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| #ifndef COBALT_WEBDRIVER_UTIL_CALL_ON_MESSAGE_LOOP_H_ |
| #define COBALT_WEBDRIVER_UTIL_CALL_ON_MESSAGE_LOOP_H_ |
| |
| #include "base/bind.h" |
| #include "base/callback.h" |
| #include "base/memory/ref_counted.h" |
| #include "base/message_loop.h" |
| #include "base/message_loop_proxy.h" |
| #include "base/synchronization/waitable_event.h" |
| |
| namespace cobalt { |
| namespace webdriver { |
| namespace util { |
| namespace internal { |
| template <class ReturnValue> |
| class CallOnMessageLoopHelper { |
| public: |
| typedef base::Callback<ReturnValue(void)> CallbackType; |
| CallOnMessageLoopHelper( |
| const scoped_refptr<base::MessageLoopProxy>& message_loop_proxy, |
| const CallbackType& callback) |
| : completed_event_(false, false) { |
| DCHECK_NE(base::MessageLoopProxy::current(), message_loop_proxy); |
| message_loop_proxy->PostTask( |
| FROM_HERE, base::Bind(&CallOnMessageLoopHelper::CallAndSignal, |
| base::Unretained(this), callback)); |
| } |
| |
| ReturnValue WaitForResult() { |
| completed_event_.Wait(); |
| return result_; |
| } |
| |
| private: |
| void CallAndSignal(const CallbackType& callback) { |
| result_ = callback.Run(); |
| completed_event_.Signal(); |
| } |
| |
| base::WaitableEvent completed_event_; |
| ReturnValue result_; |
| }; |
| |
| // Used with CallWeakOnMessageLoop. |
| template <typename T, typename ReturnValue> |
| base::optional<ReturnValue> RunWeak(const base::Callback<T*()>& get_weak, |
| const base::Callback<ReturnValue(T*)>& cb) { |
| T* weak_object = get_weak.Run(); |
| if (weak_object) { |
| return cb.Run(weak_object); |
| } else { |
| return base::nullopt; |
| } |
| } |
| } // namespace internal |
| |
| // Call the base::Callback on the specified message loop and wait for it to |
| // complete, then return the result of the callback. |
| template <class ReturnValue> |
| ReturnValue CallOnMessageLoop( |
| const scoped_refptr<base::MessageLoopProxy>& message_loop_proxy, |
| const base::Callback<ReturnValue(void)>& callback) { |
| internal::CallOnMessageLoopHelper<ReturnValue> call_helper(message_loop_proxy, |
| callback); |
| return call_helper.WaitForResult(); |
| } |
| |
| // Supports a common pattern in the various XXXDriver classes. |
| // On the provided message loop, calls RunWeak which will run the callback |cb| |
| // if |get_weak| returns a non-NULL pointer. RunWeak will return the result of |
| // the callback, or base::nullopt if |get_weak| returned NULL and the callback |
| // wasn't run. |
| // If the return value from RunWeak is valid, return a CommandResult that wraps |
| // the value. Otherwise return |no_such_object_code| to indicate the correct |
| // error. |
| template <typename T, typename ReturnValue> |
| util::CommandResult<ReturnValue> CallWeakOnMessageLoopAndReturnResult( |
| const scoped_refptr<base::MessageLoopProxy>& message_loop, |
| const base::Callback<T*()>& get_weak, |
| const base::Callback<ReturnValue(T*)>& cb, |
| protocol::Response::StatusCode no_such_object_code) { |
| typedef util::CommandResult<ReturnValue> CommandResult; |
| typedef base::optional<ReturnValue> InternalResult; |
| InternalResult result = util::CallOnMessageLoop( |
| message_loop, |
| base::Bind(&internal::RunWeak<T, ReturnValue>, get_weak, cb)); |
| if (result) { |
| return CommandResult(result.value()); |
| } else { |
| return CommandResult(no_such_object_code); |
| } |
| } |
| |
| } // namespace util |
| } // namespace webdriver |
| } // namespace cobalt |
| |
| #endif // COBALT_WEBDRIVER_UTIL_CALL_ON_MESSAGE_LOOP_H_ |