concurrent_queue.h

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/*
        This file is part of cpp-ethereum.

        cpp-ethereum is free software: you can redistribute it and/or modify
        it under the terms of the GNU General Public License as published by
        the Free Software Foundation, either version 3 of the License, or
        (at your option) any later version.

        cpp-ethereum is distributed in the hope that it will be useful,
        but WITHOUT ANY WARRANTY; without even the implied warranty of
        MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
        GNU General Public License for more details.

        You should have received a copy of the GNU General Public License
        along with cpp-ethereum.  If not, see <http://www.gnu.org/licenses/>.
*/
#pragma once
#include <utility>
#include <queue>
#include <condition_variable>
#include <mutex>


namespace dev
{

template<typename _T, typename _QueueT = std::queue<_T>>
class concurrent_queue
{
public:
        template<typename _U>
        void push(_U&& _elem)
        {
                {
                        std::lock_guard<decltype(x_mutex)> guard{x_mutex};
                        m_queue.push(std::forward<_U>(_elem));
                }
                m_cv.notify_one();
        }

        _T pop()
        {
                std::unique_lock<std::mutex> lock{x_mutex};
                m_cv.wait(lock, [this]{ return !m_queue.empty(); });
                auto item = std::move(m_queue.front());
                m_queue.pop();
                return item;
        }

private:
        _QueueT m_queue;
        std::mutex x_mutex;
        std::condition_variable m_cv;
};

}