arpadboda commented on a change in pull request #746: MINIFICPP-1185 - Remove moodycamel::concurrentqueue from threadpool URL: https://github.com/apache/nifi-minifi-cpp/pull/746#discussion_r396725596
########## File path: libminifi/include/utils/ConcurrentQueue.h ########## @@ -0,0 +1,155 @@ +/** + * 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 LIBMINIFI_INCLUDE_CONCURRENT_QUEUE_H +#define LIBMINIFI_INCLUDE_CONCURRENT_QUEUE_H + +#include <deque> +#include <mutex> +#include <condition_variable> + +namespace org { +namespace apache { +namespace nifi { +namespace minifi { +namespace utils { + +template <typename T> +class ConcurrentQueue { + public: + ConcurrentQueue() = default; + virtual ~ConcurrentQueue() = default; + + ConcurrentQueue(const ConcurrentQueue& other) = delete; + ConcurrentQueue& operator=(const ConcurrentQueue& other) = delete; + ConcurrentQueue(ConcurrentQueue&& other) + : ConcurrentQueue(std::move(other), std::lock_guard<std::mutex>(other.mutex_)) {} + + ConcurrentQueue& operator=(ConcurrentQueue&& other) { + if (this != &other) { + std::lock(mtx_, other.mtx_); + std::lock_guard<std::mutex> lk1(mtx_, std::adopt_lock); + std::lock_guard<std::mutex> lk2(other.mtx_, std::adopt_lock); + queue_.swap(other.queue_); + } + return *this; + } + + virtual bool tryDequeue(T& out) { + std::unique_lock<std::mutex> lck(mtx_); + return tryDequeue(lck, out); + } + + virtual bool empty() const { + std::lock_guard<std::mutex> guard(mtx_); + return queue_.empty(); + } + + virtual size_t size() const { + std::lock_guard<std::mutex> guard(mtx_); + return queue_.size(); + } + + virtual void clear() { + std::lock_guard<std::mutex> guard(mtx_); + queue_.clear(); + } + + template <typename... Args> + void enqueue(Args&&... args) { + std::lock_guard<std::mutex> guard(mtx_); + queue_.emplace_back(std::forward<Args>(args)...); + } + + private: + ConcurrentQueue(ConcurrentQueue&& other, std::lock_guard<std::mutex>&) + : queue_( std::move(other.queue_) ) {} + + protected: + bool tryDequeue(std::unique_lock<std::mutex>& lck, T& out) { + if (!lck.owns_lock()) { + return false; + } + if (queue_.empty()) { + return false; + } + out = std::move(queue_.front()); + queue_.pop_front(); + return true; + } + std::deque<T> queue_; + mutable std::mutex mtx_; +}; + +template <typename T> +class ConditionConcurrentQueue : public ConcurrentQueue<T> { Review comment: When I was reading the private inheritance idea, my first though was "I love it". Although I realised that private inheritance would made me rewrap or copy/paste all the functions (size(), clear()) I would like to inherit from the base class without any modification on them. In case it can somehow be avoided (I found no way, but naturally open to suggestions), I absolutely favour the private inheritance. Otherwise - to avoid code duplication or needless wrappers - I would stay with the current implementation. Virtual functions are removed in the meanwhile to address that part of your concerns. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: [email protected] With regards, Apache Git Services
