コード例 #1
0
        private bool WaitForSignal(int timeoutMs)
        {
            Debug.Assert(timeoutMs > 0 || timeoutMs == -1);

            _onWait();

            while (true)
            {
                if (!WaitCore(timeoutMs))
                {
                    // Unregister the waiter. The wait subsystem used above guarantees that a thread that wakes due to a timeout does
                    // not observe a signal to the object being waited upon.
                    _separated._counts.InterlockedDecrementWaiterCount();
                    return(false);
                }

                // Unregister the waiter if this thread will not be waiting anymore, and try to acquire the semaphore
                Counts counts = _separated._counts;
                while (true)
                {
                    Debug.Assert(counts.WaiterCount != 0);
                    Counts newCounts = counts;
                    if (counts.SignalCount != 0)
                    {
                        newCounts.DecrementSignalCount();
                        newCounts.DecrementWaiterCount();
                    }

                    // This waiter has woken up and this needs to be reflected in the count of waiters signaled to wake
                    if (counts.CountOfWaitersSignaledToWake != 0)
                    {
                        newCounts.DecrementCountOfWaitersSignaledToWake();
                    }

                    Counts countsBeforeUpdate = _separated._counts.InterlockedCompareExchange(newCounts, counts);
                    if (countsBeforeUpdate == counts)
                    {
                        if (counts.SignalCount != 0)
                        {
                            return(true);
                        }
                        break;
                    }

                    counts = countsBeforeUpdate;
                }
            }
        }