OpenSpace/modules/globebrowsing/other/concurrentqueue.h

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 * OpenSpace                                                                             *
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 * Copyright (c) 2014-2016                                                               *
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#ifndef __CONCURRENT_QUEUE_H__
#define __CONCURRENT_QUEUE_H__

#include <glm/glm.hpp>
#include <memory>
#include <ostream>
#include <thread>
#include <queue>
#include <mutex>
#include <condition_variable>

namespace openspace {



/**
 * Templated thread-safe queue based on std::thread and std::queue
 */
template <typename T>
class ConcurrentQueue {
public:

    T pop() {
        std::unique_lock<std::mutex> mlock(_mutex);
        while (_queue.empty()) {
            _cond.wait(mlock);
        }
        auto item = _queue.front();
        _queue.pop();
        return item;
    }

    void pop(T& item) {
        std::unique_lock<std::mutex> mlock(_mutex);
        while (_queue.empty()) {
            _cond.wait(mlock);
        }
        item = _queue.front();
        _queue.pop();
    }

    void push(const T& item) {
        std::unique_lock<std::mutex> mlock(_mutex);
        _queue.push(item);
        mlock.unlock();
        _cond.notify_one();
    }

    void push(T&& item) {
        std::unique_lock<std::mutex> mlock(_mutex);
        _queue.push(std::move(item));
        mlock.unlock();
        _cond.notify_one();
    }

    size_t size() const{
        std::unique_lock<std::mutex> mlock(_mutex);
        size_t s = _queue.size();
        mlock.unlock();
        _cond.notify_one();
        return s;
    }

private:
    std::queue<T> _queue;
    mutable std::mutex _mutex;
    mutable std::condition_variable _cond;
};

}

#endif // __CONCURRENT_QUEUE_H__