public void Start()
{
Debug.Assert(Form1.GUIthreadHashcode == Thread.CurrentThread.GetHashCode()); // should ONLY be called from GUI thread
Debug.Assert(!timer.Enabled); // successive Start or Stop calls are BAD
Debug.WriteLine("SerialOperationTimer " + name + ": Start");
if (runningTimer != null)
{
Debug.Assert(false); // Lets have a look in the debugger NOW
throw new System.Exception("SerialOperationTimer " + name + ": Attempted 'Start' while " + runningTimer.name + " is still running");
}
// Start background processing
// Release GUI thread's lock on the serial port, so background thread can grab it
Monitor.Exit(XXX_Conn.SerialPortLockObject);
runningTimer = this;
timer.Enabled = true;
}
public void Stop()
{
Debug.Assert(Form1.GUIthreadHashcode == Thread.CurrentThread.GetHashCode()); // should ONLY be called from GUI thread
Debug.Assert(timer.Enabled); // successive Start or Stop calls are BAD
Debug.WriteLine("SerialOperationTimer " + name + ": Stop");
if (runningTimer != this)
{
Debug.Assert(false); // Lets have a look in the debugger NOW
throw new System.Exception("SerialOperationTimer " + name + ": Attempted 'Stop' while not running");
}
// Stop further background processing from being initiated,
timer.Enabled = false; // but, background processing may still be in progress from the last timer tick...
runningTimer = null;
// Purge serial input and output buffers. Clearing input buf causes any blocking read in progress in background thread to throw
// System.IO.IOException "The I/O operation has been aborted because of either a thread exit or an application request.\r\n"
if (Form1.xxConnection.PortIsOpen)
{
Form1.xxConnection.CiCommDiscardBothBuffers();
}
bool lockTaken = false;
// Now, GUI thread needs the lock back.
// 3 sec REALLY should be enough time for background thread to cleanup and release the lock:
Monitor.TryEnter(XXX_Conn.SerialPortLockObject, 3000, ref lockTaken);
if (!lockTaken)
{
throw new Exception("Serial port lock not yet released by background timer thread " + name);
}
if (Form1.xxConnection.PortIsOpen)
{
// Its possible there's still stuff in transit from device (for example, background thread just completed
// sending an ACQ command as it was stopped). So, sync up with the device...
int r = Form1.xxConnection.CiSync();
Debug.Assert(r == XXX_Conn.CI_OK);
if (r != XXX_Conn.CI_OK)
{
throw new Exception("Cannot re-sync with device after disabling timer thread " + name);
}
}
}
