Fixed AutoScale timer not stopping Redth#36

The PushServiceBase uses a timer to check the scale (if autoscaling is
enabled).  This timer was not being stopped once the service itself was
stopped and could cause exceptions to be thrown if the timer fired after
a service was stopped.

Author: Redth

Diff for: PushSharp.Common/PushServiceBase.cs

@@ -62,6 +62,10 @@ public void Stop(bool waitForQueueToFinish)
 		{
 			stopping = true;
 
+			//Stop the timer for checking scale
+			if (this.timerCheckScale != null)
+				this.timerCheckScale.Change(Timeout.Infinite, Timeout.Infinite);
+
 			//Stop all channels
 			Parallel.ForEach<PushChannelBase>(channels,
 				(channel) =>
@@ -125,7 +129,7 @@ orderby c.QueuedNotificationCount
 
 		void CheckScale()
 		{
-			if (ServiceSettings.AutoScaleChannels)
+			if (ServiceSettings.AutoScaleChannels && !this.cancelTokenSource.IsCancellationRequested && !stopping)
 			{
 				if (channels.Count <= 0)
 				{
@@ -158,10 +162,10 @@ void CheckScale()
 			}
 			else
 			{
-				while (channels.Count > ServiceSettings.Channels)
+				while (channels.Count > ServiceSettings.Channels && !this.cancelTokenSource.IsCancellationRequested && !stopping)
 					TeardownChannel();
 
-				while (channels.Count < ServiceSettings.Channels)
+				while (channels.Count < ServiceSettings.Channels && !this.cancelTokenSource.IsCancellationRequested && !stopping)
 					SpinupChannel();
 			}
 		}