Thread Timers (C# and Visual Basic)
Visual Studio 2012
The Timer class is useful for periodically running a task on a separate thread. For example, you could use a thread timer to check the status and integrity of a database or to back up critical files.
The following example starts a task every two seconds and uses a flag to initiate the Dispose method that stops the timer. This example posts status to the output window.
private class StateObjClass { // Used to hold parameters for calls to TimerTask. public int SomeValue; public System.Threading.Timer TimerReference; public bool TimerCanceled; } public void RunTimer() { StateObjClass StateObj = new StateObjClass(); StateObj.TimerCanceled = false; StateObj.SomeValue = 1; System.Threading.TimerCallback TimerDelegate = new System.Threading.TimerCallback(TimerTask); // Create a timer that calls a procedure every 2 seconds. // Note: There is no Start method; the timer starts running as soon as // the instance is created. System.Threading.Timer TimerItem = new System.Threading.Timer(TimerDelegate, StateObj, 2000, 2000); // Save a reference for Dispose. StateObj.TimerReference = TimerItem; // Run for ten loops. while (StateObj.SomeValue < 10) { // Wait one second. System.Threading.Thread.Sleep(1000); } // Request Dispose of the timer object. StateObj.TimerCanceled = true; } private void TimerTask(object StateObj) { StateObjClass State = (StateObjClass)StateObj; // Use the interlocked class to increment the counter variable. System.Threading.Interlocked.Increment(ref State.SomeValue); System.Diagnostics.Debug.WriteLine("Launched new thread " + DateTime.Now.ToString()); if (State.TimerCanceled) // Dispose Requested. { State.TimerReference.Dispose(); System.Diagnostics.Debug.WriteLine("Done " + DateTime.Now.ToString()); } }
Thread timers are particularly useful when the Timer object is unavailable, such as when you are developing console applications.
