| /** |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you 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 LIB_FUTURE_H_ |
| #define LIB_FUTURE_H_ |
| |
| #include <functional> |
| #include <mutex> |
| #include <memory> |
| #include <condition_variable> |
| |
| #include <list> |
| |
| typedef std::unique_lock<std::mutex> Lock; |
| |
| namespace pulsar { |
| |
| template <typename Result, typename Type> |
| struct InternalState { |
| std::mutex mutex; |
| std::condition_variable condition; |
| Result result; |
| Type value; |
| bool complete; |
| |
| std::list<typename std::function<void(Result, const Type&)> > listeners; |
| }; |
| |
| template <typename Result, typename Type> |
| class Future { |
| public: |
| typedef std::function<void(Result, const Type&)> ListenerCallback; |
| |
| Future& addListener(ListenerCallback callback) { |
| InternalState<Result, Type>* state = state_.get(); |
| Lock lock(state->mutex); |
| |
| if (state->complete) { |
| lock.unlock(); |
| callback(state->result, state->value); |
| } else { |
| state->listeners.push_back(callback); |
| } |
| |
| return *this; |
| } |
| |
| Result get(Type& result) { |
| InternalState<Result, Type>* state = state_.get(); |
| Lock lock(state->mutex); |
| |
| if (!state->complete) { |
| // Wait for result |
| while (!state->complete) { |
| state->condition.wait(lock); |
| } |
| } |
| |
| result = state->value; |
| return state->result; |
| } |
| |
| private: |
| typedef std::shared_ptr<InternalState<Result, Type> > InternalStatePtr; |
| Future(InternalStatePtr state) : state_(state) {} |
| |
| std::shared_ptr<InternalState<Result, Type> > state_; |
| |
| template <typename U, typename V> |
| friend class Promise; |
| }; |
| |
| template <typename Result, typename Type> |
| class Promise { |
| public: |
| Promise() : state_(std::make_shared<InternalState<Result, Type> >()) {} |
| |
| bool setValue(const Type& value) const { |
| static Result DEFAULT_RESULT; |
| InternalState<Result, Type>* state = state_.get(); |
| Lock lock(state->mutex); |
| |
| if (state->complete) { |
| return false; |
| } |
| |
| state->value = value; |
| state->result = DEFAULT_RESULT; |
| state->complete = true; |
| |
| decltype(state->listeners) listeners; |
| listeners.swap(state->listeners); |
| |
| lock.unlock(); |
| |
| for (auto& callback : listeners) { |
| callback(DEFAULT_RESULT, value); |
| } |
| |
| state->condition.notify_all(); |
| return true; |
| } |
| |
| bool setFailed(Result result) const { |
| static Type DEFAULT_VALUE; |
| InternalState<Result, Type>* state = state_.get(); |
| Lock lock(state->mutex); |
| |
| if (state->complete) { |
| return false; |
| } |
| |
| state->result = result; |
| state->complete = true; |
| |
| decltype(state->listeners) listeners; |
| listeners.swap(state->listeners); |
| |
| lock.unlock(); |
| |
| for (auto& callback : listeners) { |
| callback(result, DEFAULT_VALUE); |
| } |
| |
| state->condition.notify_all(); |
| return true; |
| } |
| |
| bool isComplete() const { |
| InternalState<Result, Type>* state = state_.get(); |
| Lock lock(state->mutex); |
| return state->complete; |
| } |
| |
| Future<Result, Type> getFuture() const { return Future<Result, Type>(state_); } |
| |
| private: |
| typedef std::function<void(Result, const Type&)> ListenerCallback; |
| std::shared_ptr<InternalState<Result, Type> > state_; |
| }; |
| |
| class Void {}; |
| |
| } /* namespace pulsar */ |
| |
| #endif /* LIB_FUTURE_H_ */ |