Handle AppDomain unload

Fixes #826

Author: lukebakken

projects/RabbitMQ.Client/client/api/ConnectionFactory.cs

@@ -723,14 +723,15 @@ private List<AmqpTcpEndpoint> LocalEndpoints()
 
         private static string EnsureClientProvidedNameLength(string clientProvidedName)
         {
-            if (clientProvidedName.Length > InternalConstants.DefaultRabbitMqMaxClientProvideNameLength)
+            if (clientProvidedName != null)
             {
-                return clientProvidedName.Substring(0, InternalConstants.DefaultRabbitMqMaxClientProvideNameLength);
-            }
-            else
-            {
-                return clientProvidedName;
+                if (clientProvidedName.Length > InternalConstants.DefaultRabbitMqMaxClientProvideNameLength)
+                {
+                    return clientProvidedName.Substring(0, InternalConstants.DefaultRabbitMqMaxClientProvideNameLength);
+                }
             }
+
+            return clientProvidedName;
         }
     }
 }

projects/RabbitMQ.Client/client/impl/AutorecoveringConnection.Recovery.cs

@@ -71,11 +71,23 @@ static bool ShouldTriggerConnectionRecovery(ShutdownEventArgs args)
                     }
                 }
 
-                // happens when EOF is reached, e.g. due to RabbitMQ node
-                // connectivity loss or abrupt shutdown
                 if (args.Initiator == ShutdownInitiator.Library)
                 {
-                    return true;
+                    /*
+                     * https://github.com/rabbitmq/rabbitmq-dotnet-client/issues/826
+                     * Happens when an AppDomain is unloaded
+                     */
+                    if (args.Exception is ThreadAbortException &&
+                        args.ReplyCode == Constants.InternalError)
+                    {
+                        return false;
+                    }
+                    else
+                    {
+                        // happens when EOF is reached, e.g. due to RabbitMQ node
+                        // connectivity loss or abrupt shutdown
+                        return true;
+                    }
                 }
 
                 return false;

projects/RabbitMQ.Client/client/impl/Connection.Receive.cs

@@ -53,6 +53,19 @@ private async Task MainLoop()
                 await ReceiveLoopAsync(mainLoopToken)
                     .ConfigureAwait(false);
             }
+#if NETSTANDARD
+            catch (ThreadAbortException taex)
+            {
+                /*
+                 * https://github.com/rabbitmq/rabbitmq-dotnet-client/issues/826
+                 */
+                var ea = new ShutdownEventArgs(ShutdownInitiator.Library,
+                    Constants.InternalError,
+                    "Thread aborted (AppDomain unloaded?)",
+                    exception: taex);
+                HandleMainLoopException(ea);
+            }
+#endif
             catch (EndOfStreamException eose)
             {
                 // Possible heartbeat exception