fixing timeouts for ackable messages (#1576)

* fixing timeouts for ackable messages

* fixing timeouts for ackable messages, refactoring to avoid future runtime exceptions

* fixing timeouts for ackable messages, refactoring to avoid future runtime exceptions

* fixing timeouts for ackable messages, refactoring to avoid future runtime exceptions

* fixing timeouts for ackable messages, refactoring to avoid future runtime exceptions

* reworking the fix with simplified Clone implementation

* reworking the fix with simplified Clone implementation

* reworking the fix with simplified Clone implementation & cleanup

* addressing code review

* addressing code review

* removing an extra space

Author: KKhurin

src/Microsoft.Azure.SignalR.Common/ServiceConnections/MultiEndpointMessageWriter.cs

@@ -42,7 +42,7 @@ public async Task<bool> WriteAckableMessageAsync(ServiceMessage serviceMessage,
 
             var writeMessageTask = WriteMultiEndpointMessageAsync(serviceMessage, async connection =>
             {
-                var succeeded = await connection.WriteAckableMessageAsync(serviceMessage, cancellationToken);
+                var succeeded = await connection.WriteAckableMessageAsync(serviceMessage.Clone(), cancellationToken);
                 if (succeeded)
                 {
                     tcs.TrySetResult(true);

src/Microsoft.Azure.SignalR.Protocols/ServiceMessage.cs

@@ -12,6 +12,11 @@ namespace Microsoft.Azure.SignalR.Protocol
     /// </summary>
     public abstract class ServiceMessage
     {
+        /// <summary>
+        /// Clone should make a copy of everything that may get modified throughout the lifetime of the message
+        /// The default implementation is a shallow copy as it fits the current needs.
+        /// </summary>
+        public virtual ServiceMessage Clone() => MemberwiseClone() as ServiceMessage;
     }
 
     /// <summary>