messageQueue.hpp

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#ifndef RTCTK_DATATASK_MESSAGEQUEUE_HPP
#define RTCTK_DATATASK_MESSAGEQUEUE_HPP
 
#include <mutex>
#include <condition_variable>
#include <queue>
#include <optional>
 
namespace rtctk::dataTask {
template <class T>
class MessageQueue {
public:
 
    inline void Post(T const& value) {
        {
            std::unique_lock<std::mutex> lock(m_mtx);
            m_queue.push(value);
        }
        m_cv.notify_one();
    }
 
    inline T Pend() {
        std::unique_lock<std::mutex> lock(m_mtx);
        m_cv.wait(lock, [&]{return not m_queue.empty();});
        auto ret = m_queue.front();
        m_queue.pop();
        return ret;
    }
 
    template <class Rep, class Period>
    inline T Pend(std::chrono::duration<Rep, Period> timeout) {
        std::unique_lock<std::mutex> lock(m_mtx);
        auto to = m_cv.wait_for(lock, timeout, [&]{return not m_queue.empty();});
        if(to == false) {
            throw(std::runtime_error("MessageQueue.Pend() timed out"));
        }
        auto ret = m_queue.front();
        m_queue.pop();
        return ret;
    }
 
    inline std::optional<T> TryPend() { // TODO: revisit naming
        std::unique_lock<std::mutex> lock(m_mtx);
        if(not m_queue.empty()) {
            auto ret = m_queue.front();
            m_queue.pop();
            return ret;
        }else {
            return {};
        }
    }
 
    inline void Clear() {
        std::unique_lock<std::mutex> lock(m_mtx);
        while(not m_queue.empty()) {
            m_queue.pop();
        }
    }
 
private:
    std::mutex m_mtx;
    std::condition_variable m_cv;
    std::queue<T> m_queue;
};
 
} // namespace
 
#endif