| /** |
| * 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 _TUBEMQ_FUTURE_H_ |
| #define _TUBEMQ_FUTURE_H_ |
| |
| #include <condition_variable> |
| #include <functional> |
| #include <memory> |
| #include <mutex> |
| #include <vector> |
| |
| #include "tubemq/tubemq_errcode.h" |
| |
| namespace tubemq { |
| |
| template <typename Value> |
| struct FutureInnerState { |
| std::mutex mutex_; |
| std::condition_variable condition_; |
| ErrorCode error_code_; |
| Value value_; |
| bool ready_ = false; |
| bool failed_ = false; |
| using FutureCallBackFunc = std::function<void(ErrorCode, const Value&)>; |
| std::vector<FutureCallBackFunc> callbacks_; |
| }; |
| |
| template <typename Value> |
| class Future { |
| public: |
| using FutureInnerStatePtr = std::shared_ptr<FutureInnerState<Value> >; |
| using FutureCallBackFunc = std::function<void(ErrorCode, const Value&)>; |
| Future& AddCallBack(FutureCallBackFunc callback) { |
| Lock lock(state_->mutex_); |
| |
| if (state_->ready_) { |
| lock.unlock(); |
| callback(state_->error_code_, state_->value_); |
| } else { |
| state_->callbacks_.push_back(callback); |
| } |
| return *this; |
| } |
| |
| ErrorCode Get(Value& value) { |
| Lock lock(state_->mutex_); |
| |
| if (!state_->ready_) { |
| // Wait for error_code_ |
| while (!state_->ready_) { |
| state_->condition_.wait(lock); |
| } |
| } |
| |
| value = state_->value_; |
| return state_->error_code_; |
| } |
| |
| private: |
| using Lock = std::unique_lock<std::mutex>; |
| explicit Future(FutureInnerStatePtr state) : state_(state) {} |
| FutureInnerStatePtr state_; |
| |
| template <typename V> |
| friend class Promise; |
| }; |
| |
| template <typename Value> |
| class Promise { |
| public: |
| using FutureInnerStatePtr = std::shared_ptr<FutureInnerState<Value> >; |
| using FutureCallBackFunc = std::function<void(ErrorCode, const Value&)>; |
| Promise() : state_(std::make_shared<FutureInnerState<Value> >()) {} |
| |
| bool SetValue(const Value& value) { |
| Lock lock(state_->mutex_); |
| |
| if (state_->ready_) { |
| return false; |
| } |
| |
| state_->value_ = value; |
| state_->ready_ = true; |
| |
| callbackAndNotify(); |
| return true; |
| } |
| |
| bool SetFailed(const ErrorCode& error_code_) { |
| Lock lock(state_->mutex_); |
| |
| if (state_->ready_) { |
| return false; |
| } |
| |
| state_->error_code_ = error_code_; |
| state_->ready_ = true; |
| state_->failed_ = true; |
| |
| callbackAndNotify(); |
| return true; |
| } |
| |
| bool IsReady() const { return state_->ready_; } |
| |
| bool IsFailed() const { return state_->failed_; } |
| |
| Future<Value> GetFuture() const { return Future<Value>(state_); } |
| |
| private: |
| void callbackAndNotify() { |
| for (auto callback : state_->callbacks_) { |
| callback(state_->error_code_, state_->value_); |
| } |
| state_->callbacks_.clear(); |
| state_->condition_.notify_all(); |
| } |
| |
| private: |
| using Lock = std::unique_lock<std::mutex>; |
| FutureInnerStatePtr state_; |
| }; |
| |
| } /* namespace tubemq */ |
| |
| #endif /* _TUBEMQ_FUTURE_H_ */ |