private static Mutex mNamedMutex; //Use this to avoid having to throw an exception on normal load behaviour
/// <summary>
/// Runs the application, and listens for signals from subsequent instances
/// </summary>
public static void RunAppAsServiceHost(IPriorInstance instance, string channelUri)
{
System.Diagnostics.Debug.Assert(mNamedMutex != null, "Expecting QueryPriorInstance to be called before RunAppAsServiceHost");
ServiceHost service = new ServiceHost(instance, new Uri(channelUri));
try
{
try
{
service.AddServiceEndpoint(typeof(IPriorInstance), new NetNamedPipeBinding(), new Uri(channelUri));
service.Open();
}
catch (CommunicationException ex)
{
System.Diagnostics.Trace.TraceWarning("Could not start listening as a prior instance: " + ex.Message);
//Attempt a close, if at all possible
try { service.Close(); }
catch (Exception) { }
service = null;
}
instance.Run();
}
finally
{
if (service != null)
{
service.Close();
}
}
GC.KeepAlive(mNamedMutex); //Make sure the mutex sticks around until the app finishes running.
}
/// <summary>
/// If a prior instance was running, sends the args to it and returns true. Otherwise, returns false.
/// </summary>
public static bool QueryPriorInstance(string[] args, string channelUri)
{
bool createdNew;
mNamedMutex = new Mutex(true, channelUri, out createdNew);
if (!createdNew) //No previous instance was running, if a new mutex was created.
{
try
{
EndpointAddress address = new EndpointAddress(channelUri);
IPriorInstance instance = ChannelFactory <IPriorInstance> .CreateChannel(new NetNamedPipeBinding(), address);
try
{
instance.Signal(args);
}
finally
{
((ICommunicationObject)instance).Close();
}
return(true);
}
catch (Exception ex)
{
System.Diagnostics.Trace.TraceWarning("Could not communicate with existing prior instance: " + ex.Message);
return(false);
}
}
return(false);
}
/// <summary>
/// If a prior instance was running, sends the args to it and returns true. Otherwise, returns false.
/// </summary>
public static bool QueryPriorInstance(string[] args, string channelUri)
{
mNamedMutex = new EventWaitHandle(false, EventResetMode.ManualReset, channelUri, out mOwnsMutex);
if (!mOwnsMutex) //No previous instance was running, if a new mutex was created.
{
//If a new mutex was not created, then wait for it to be signalled, indicating that the instance that does own it is now ready to recieve incoming signals
if (mNamedMutex.WaitOne(WaitForFirstInstanceTimeout))
{
try
{
EndpointAddress address = new EndpointAddress(channelUri);
IPriorInstance instance = ChannelFactory <IPriorInstance> .CreateChannel(new NetNamedPipeBinding(), address);
try
{
instance.Signal(args);
}
finally
{
((ICommunicationObject)instance).Close();
}
return(true);
}
catch (Exception ex)
{
System.Diagnostics.Trace.TraceWarning("Could not communicate with existing prior instance: " + ex.Message);
return(false);
}
}
else
{
System.Diagnostics.Trace.TraceWarning("Could not communicate with existing prior instance: timed out");
return(false);
}
}
return(false);
}
