如何确定是否在辅助线程中调用了EventWaitHandle.WaitOne

Question

I have a main thread which spawns a secondary thread. This secondary thread is using the EventWaitHandle.WaitOne to wait after performing some particular operation.

Is there any way for the main thread to be signalled when the secondary thread goes to the wait state?

I tried using System.Threading.ThreadState property to determine whether the thread is in WaitSleepJoin state when the WaitOne() -method is called, but this approach does not seem to work as the thread always appears to be in Running state.

Answer 1

You can use the second ManualResetEvent to signal main thread:

in the worker thread:

signalEWH.Set();

commonEWH.WaitOne();

signalEWM.Reset();

in the main thread

var isWaiting = signalEWH.WaitOne(0);

I have wrote the fololowing test app and it works fine to me

      class Program
{
    static void Main(string[] args)
    {
        var thr = new Thread(new ThreadStart(SecondThread));
        thr.IsBackground = true;
        thr.Start();

        firstEvent.WaitOne();

        var isSleep = thr.ThreadState.HasFlag(ThreadState.WaitSleepJoin);
    }

    static ManualResetEvent firstEvent = new ManualResetEvent(false);
    static ManualResetEvent secondEvent = new ManualResetEvent(false);

    static void SecondThread()
    {
        firstEvent.Set();
        secondEvent.WaitOne();
        firstEvent.Reset();
    }
}