cvd/message_queue.h

#ifndef CVD_INCLUDE_MESSAGE_QUEUE_H
#define CVD_INCLUDE_MESSAGE_QUEUE_H

#include <cvd/synchronized.h>
#include <semaphore.h>
#include <deque>

namespace CVD
{

template<class C> class MessageQueue
{
    public:
        MessageQueue()
        {
            sem_init(&empty_slots, 0, 0);
        }

        ~MessageQueue()
        {
            sem_destroy(&empty_slots);
        }

        void write(const C& message)
        {   
            //Lock the queue, so it can be safely used.
            queue_mutex.lock();
            queue.push_back(message);
            queue_mutex.unlock();

            sem_post(&empty_slots);
        }
        
        C read()
        {
            sem_wait(&empty_slots);
            C ret;

            queue_mutex.lock();
            ret = queue.front();
            queue.pop_front();
            queue_mutex.unlock();

            return ret;
        }

        int size()
        {
            int s;
            sem_getvalue(&empty_slots, &s);
            return s;
        }

    private:
        Synchronized queue_mutex;
        std::deque<C> queue;
        sem_t empty_slots;
};

}
#endif