Automatically reconnect to the server using an exponential backoff algorithm if we lose our connection.

RhinoReminds/ClientListener.cs

@@ -29,7 +29,21 @@ namespace RhinoReminds
 		public string ReminderFilePath { get; set; } = "./reminders.xml";
 		private ReminderList reminderList = new ReminderList();
 
+
 		private XmppClient client;
+		/// <summary>
+		/// The number of seconds to wait before trying to reconnect to the 
+		/// server again if we loose our connection again.
+		/// </summary>
+		private int nextBackoffDelay = 1;
+		private int defaultBackoffDelay = 1;
+		private float backoffDelayMultiplier = 2;
+		/// <summary>
+		/// If a connection attempt doesn't succeed in this number of seconds,
+		/// give up and try again later.
+		/// </summary>
+		private int giveUpTimeout = 30;
+
 
 		public ClientListener(string inJid, string inPassword)
 		{
@@ -51,19 +65,36 @@ namespace RhinoReminds
 			client.SubscriptionRequest += subscriptionRequestHandler;
 
 			// Connect to the server. This starts it's own thread that doesn't block the program exiting, apparently
+			await connect();
+
+			//client.SetStatus(Availability.Online);
+
+			await watchForReminders();
+		}
+
+		private async Task<bool> connect()
+		{
+			if (client.Connected)
+				return true;
+
+			DateTime startTime = DateTime.Now;
 			client.Connect();
 
 			while (!client.Connected)
+			{
+				if ((DateTime.Now - startTime).TotalSeconds > giveUpTimeout)
+					return false;
+				
 				await Task.Delay(100);
+			}
 
 			Console.WriteLine($"[Rhino/Setup] Connected as {Jid}");
 
-			//client.SetStatus(Availability.Online);
-
-			await watchForReminders();
+			return true;
 		}
 
 		#region XMPP Event Handling
+
 		private bool subscriptionRequestHandler(Jid from)
 		{
 			if (!AllowedDomains.Contains("*") && !AllowedDomains.Contains(from.Domain)) {
@@ -77,6 +108,13 @@ namespace RhinoReminds
 		private void errorHandler(object sender, S22.Xmpp.Im.ErrorEventArgs e)
 		{
 			Console.Error.WriteLine($"Error {e.Reason}: {e.Exception}");
+			Console.Error.WriteLine($"Reconnecting in {TimeSpan.FromSeconds(nextBackoffDelay).ToString()}.");
+
+			Task.Delay(nextBackoffDelay * 1000).Wait();
+			if (!connect().Result)
+				nextBackoffDelay = (int)Math.Ceiling(nextBackoffDelay * backoffDelayMultiplier);
+			else
+				nextBackoffDelay = defaultBackoffDelay;
 		}
 
 		private void messageHandlerRoot(object sender, MessageEventArgs eventArgs)
@@ -96,6 +134,9 @@ namespace RhinoReminds
 			}
 		}
 
+		#endregion
+
+
 		public void SetAvatar(string avatarFilepath)
 		{
 			if (!client.Connected)
@@ -219,6 +260,7 @@ namespace RhinoReminds
 			}
 		}
 
+
 		#region Outgoing
 		/// <summary>
 		/// Sends a chat message to the specified JID.