Fixed APN Enhanced format error detection

The APNS Enhanced format returns a response if a notification failed,
but then it also closes the connection.  This allows for a possibility
of sending one notification, then sending a second one immediately
after, and then getting notified that the first one failed.  What
happens in this case is that the second one looks like it's been sent to
us, but apple closes the stream after the second one was sent, without
acknowledging that it failed or wasn't sent.  This means we have to wait
for possible errors from each message on the connection before sending
the next.  This sucks, and means an added 250 ms delay to sending each
message.  This also means that to speed up message delivery, more
Notification Channels are needed to scale across connections/threads.
Unavoidable if the Enhanced format is to be used (which provides the
ability to expire notifications as well as error reporting).

Author: Redth

PushSharp.Apple/ApplePushChannel.cs

@@ -57,7 +57,8 @@ public ApplePushChannel(ApplePushChannelSettings settings) : base(settings)
 			taskCleanup.ContinueWith((t) => { var ex = t.Exception; }, TaskContinuationOptions.OnlyOnFaulted);
 			taskCleanup.Start();
 		}
-		
+
+		object streamWriteLock = new object();
 		int reconnectDelay = 3000;
 		float reconnectBackoffMultiplier = 1.5f;
 
@@ -75,8 +76,6 @@ protected override void SendNotification(Common.Notification notification)
 		{
 			var appleNotification = notification as AppleNotification;
 
-			Connect();
-
 			bool isOkToSend = true;
 			byte[] notificationData = new byte[] {};
 
@@ -94,12 +93,19 @@ protected override void SendNotification(Common.Notification notification)
 
 			if (isOkToSend)
 			{
+				Connect();
+				
 				try 
-				{ 
-					stream.Write(notificationData);
-					sentNotifications.TryAdd(appleNotification.Identifier, new SentNotification(appleNotification));
+				{
+					lock (streamWriteLock)
+					{
+						stream.Write(notificationData);
+						Console.WriteLine("Wrote Notification: " + appleNotification.Identifier);
+						sentNotifications.TryAdd(appleNotification.Identifier, new SentNotification(appleNotification));
+						Thread.Sleep(150);
+					}
 				}
-				catch 
+				catch (Exception ex)
 				{ 
 					this.QueueNotification(notification); 
 				} //If this failed, we probably had a networking error, so let's requeue the notification
@@ -117,28 +123,32 @@ public override void Stop(bool waitForQueueToDrain)
 
 		void Reader()
 		{
-			//try
-			//{
+			try
+			{
 				var result = stream.BeginRead(readBuffer, 0, 6, new AsyncCallback((asyncResult) =>
 				{
-					//try
-					//{
+					try
+					{
 						var bytesRead = stream.EndRead(asyncResult);
 
+						//Console.WriteLine("End Read: " + bytesRead + " bytes read.");
+
 						if (bytesRead > 0)
 						{
 							//Get the enhanced format response
 							// byte 0 is always '1', byte 1 is the status, bytes 2,3,4,5 are the identifier of the notification
 							var status = readBuffer[1];
 							var identifier = IPAddress.NetworkToHostOrder(BitConverter.ToInt32(readBuffer, 2));
 
+							Console.WriteLine(status + "=" + identifier);
+
 							SentNotification sentNotification = null;
-							
+
 							//Gets the matching notification and removes it from the sent queue at the same time
 							sentNotifications.TryRemove(identifier, out sentNotification);
 
 							if (sentNotification != null)
-							{ 
+							{
 								var nfex = new NotificationFailureException(status, sentNotification.Notification);
 
 								//Raise alert that notification failed
@@ -149,15 +159,24 @@ void Reader()
 							Reader();
 						}
 						else
+						{
 							connected = false;
-					//}
-					//catch { }
+							Console.WriteLine("Disconnected");
+						}
+					}
+					catch (Exception ex)
+					{
+						Console.WriteLine(ex.ToString());
+					}
 
 					//Otherwise, our connection was closed
 
 				}), null);
-			//}
-//			catch { }
+			}
+			catch (Exception ex)
+			{
+				Console.WriteLine(ex.ToString());
+			}
 		}
 
 
@@ -285,6 +304,7 @@ void connect()
 				throw new ConnectionFailureException("SSL Stream is not Writable", null);
 
 			//Start reading from the stream asynchronously
+			Console.WriteLine("Connect -> Reader()");
 			Reader();
 		}
 

PushSharp.Sample/Program.cs

@@ -40,13 +40,17 @@ static void Main(string[] args)
 				.WithSound("default")
 				.WithBadge(7));
 
+			//System.Threading.Thread.Sleep(2000);
+
 			//Fluent construction of an iOS notification
 			push.QueueNotification(NotificationFactory.Apple()
-				.ForDeviceToken("2071737321559691b28fffa1aa4c8259d970fe0fc496794ad0486552fc9ec3db")
+				.ForDeviceToken("0071737321559691b28fffa1aa4c8259d970fe0fc496794ad0486552fc9ec3db")
 				.WithAlert("Alert Text 2!")
 				.WithSound("default")
 				.WithBadge(7));
 
+			//System.Threading.Thread.Sleep(2000);
+
 			//Fluent construction of an iOS notification
 			push.QueueNotification(NotificationFactory.Apple()
 				.ForDeviceToken("1071737321559691b28fffa1aa4c8259d970fe0fc496794ad0486552fc9ec3db")