Method enqueue_or_timeout

benchmarks/dlib/pipe/pipe_kernel_1.h:488–575

        typename T
        >
    bool pipe<T>::
    enqueue_or_timeout (
        T& item,
        unsigned long timeout
    )
    {
        auto_mutex M(m);
        ++enqueue_waiters;

        // wait until there is room or we are disabled or 
        // we run out of time.
        bool timed_out = false;
        while (pipe_size == pipe_max_size && enabled && enqueue_enabled &&
               !(pipe_max_size == 0 && dequeue_waiters > 0 && first == 1) )
        {
            if (timeout == 0 || enqueue_sig.wait_or_timeout(timeout) == false)
            {
                timed_out = true;
                break;
            }
        }

        if (enabled == false || timed_out || enqueue_enabled == false)
        {
            --enqueue_waiters;
            // let the destructor know we are unblocking
            unblock_sig.broadcast();
            return false;
        }

        // set the appropriate values for first and last
        if (pipe_size == 0)
        {
            first = 0;
            last = 0;
        }
        else
        {
            last = (last+1)%pipe_max_size;
        }


        exchange(item,data[last]);

        // wake up a call to dequeue() if there are any currently blocked
        if (dequeue_waiters > 0)
            dequeue_sig.signal();

        if (pipe_max_size > 0)
        {
            ++pipe_size;
        }
        else
        {
            // wait for a dequeue to take the item out
            while (last == 0 && enabled && enqueue_enabled)
                enqueue_sig.wait();