Stopping timer in its callback method

Question

I have a System.Threading.Timer that calls its appropriate event handler (callback) every 10 ms. The method itself is not reentrant and can

Answer 1

A couple possible solutions:

• have the real work done in yet another thread delegate that's waiting on an event. The timer callback merely signals the event. The worker thread cannot be reentered, as it's a single thread that does its work only when the event is signaled. The timer is reentrant, since all it does is signal the event (seems a little roundabout and wasteful, but it'll work)
• have the timer created with only a start timeout and no periodic timeout so it'll fire only once. The timer callback will dispose of that timer object and create a new one when it has completed its work that will also only fire once.

You may be able to manage option #2 without disposing/creating a new object by using the Change() method of the original timer object, but I'm not sure what the behavior is exactly of calling Change() with a new start timeout after the first timeout has expired. That would be worth a test or two.

Edit:

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I did the test - manipulating the timer as a restartable one-shot seems to work perfectly, and it's much simpler than the other methods. Here's some sample code based on yours as a starting point (a few details may have changed to get it to compile on my machine):

private Timer _creatorTimer;

// BackgroundWorker's work
private void CreatorWork(object sender, EventArgs e) {
    // note: there's only a start timeout, and no repeat timeout
    //   so this will fire only once
    _creatorTimer = new Timer(CreatorLoop, null, 1000, Timeout.Infinite);

    // some other code that worker is doing while the timer is active
    // ...
    // ...
}

private void CreatorLoop(object state) {
    Console.WriteLine( "In CreatorLoop...");
    /*
        ... Work here
    */
    Thread.Sleep( 3000);

    // Reenable timer
    Console.WriteLine( "Exiting...");

    // now we reset the timer's start time, so it'll fire again
    //   there's no chance of reentrancy, except for actually
    //   exiting the method (and there's no danger even if that
    //   happens because it's safe at this point).
    _creatorTimer.Change(1000, Timeout.Infinite);
}