semaphore.hpp

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#ifndef RTCTK_DATATASK_SEMAPHORE_HPP
#define RTCTK_DATATASK_SEMAPHORE_HPP
 
#include <mutex>
#include <condition_variable>
 
namespace rtctk::dataTask {
class Semaphore {
public:
    Semaphore (int count = 0)
    : m_count(count)
    {
    }
 
    inline void Post() { // Signal
        {
            std::unique_lock<std::mutex> lock(m_mtx);
            ++m_count;
        }
        m_cv.notify_one();
    }
 
    inline void Wait() { // Wait
        std::unique_lock<std::mutex> lock(m_mtx);
        m_cv.wait(lock, [&]{return m_count != 0;});
        --m_count;
    }
 
    template <class Rep, class Period>
    inline void Wait(std::chrono::duration<Rep, Period> timeout) {
        std::unique_lock<std::mutex> lock(m_mtx);
        auto ret = m_cv.wait_for(lock, timeout, [&]{return m_count != 0;});
        if(ret == false) {
            throw(std::runtime_error("Semaphor.Wait() timed out"));
        }
        --m_count;
    }
 
    inline bool TryWait() {
        std::unique_lock<std::mutex> lock(m_mtx);
        bool ret = false;
        if(m_count > 0) {
            --m_count;
            ret = true;
        }
        return ret;
    }
 
    inline void Clear() {
        std::unique_lock<std::mutex> lock(m_mtx);
        m_count = 0;
    }
 
private:
    int m_count;
    std::mutex m_mtx;
    std::condition_variable m_cv;
};
 
} // namespace
 
#endif