Monitoring cannot process metrics for processed polymorphic messages

src/ServiceControl.Monitoring.AcceptanceTests/When_querying_queue_length_data.cs

@@ -125,7 +125,11 @@ public Task Handle(SampleMessage message, IMessageHandlerContext context)
             }
         }
 
-        class SampleMessage : IMessage
+        class SampleMessage : SampleBaseMessage
+        {
+        }
+
+        class SampleBaseMessage : IMessage
         {
         }
 

src/ServiceControl.Monitoring.AcceptanceTests/When_querying_retries_data.cs

@@ -77,7 +77,11 @@ class TestContext : ScenarioContext
             public bool ShuttingDown { get; set; }
         }
 
-        class SampleMessage : IMessage
+        class SampleMessage : SampleBaseMessage
+        {
+        }
+
+        class SampleBaseMessage : IMessage
         {
         }
     }

src/ServiceControl.Monitoring.AcceptanceTests/When_querying_timings_data.cs

@@ -63,7 +63,11 @@ class Context : ScenarioContext
         {
         }
 
-        class SampleMessage : IMessage
+        class SampleMessage : SampleBaseMessage
+        {
+        }
+
+        class SampleBaseMessage : IMessage
         {
         }
     }

src/ServiceControl.Monitoring/Infrastructure/EndpointMessageType.cs

@@ -1,11 +1,19 @@
 namespace ServiceControl.Monitoring.Infrastructure
 {
+    using System;
+
     public readonly struct EndpointMessageType
     {
-        public EndpointMessageType(string endpointName, string messageType)
+        public EndpointMessageType(string endpointName, string enclosedMessageTypes)
         {
+            var index = enclosedMessageTypes.IndexOf(';');
+
+            var firstType = index != -1
+                ? enclosedMessageTypes.Substring(0, index)
+                : enclosedMessageTypes;
+
             EndpointName = endpointName;
-            MessageType = messageType;
+            MessageType = firstType;
         }
 
         public string EndpointName { get; }

src/ServiceControl.Monitoring/Infrastructure/MessageTypeTracker.cs

@@ -15,7 +15,7 @@ public Task Handle(TaggedLongValueOccurrence message, IMessageHandlerContext con
         {
             var endpointName = context.MessageHeaders[Headers.OriginatingEndpoint];
 
-            registry.Record(new EndpointMessageType(endpointName, message.TagValue));
+            registry.Record(new EndpointMessageType(endpointName, enclosedMessageTypes: message.TagValue));
 
             return Task.CompletedTask;
         }

src/ServiceControl.Monitoring/Retries/TaggedLongValueOccurrenceHandler.cs

@@ -19,7 +19,7 @@ public Task Handle(TaggedLongValueOccurrence message, IMessageHandlerContext con
 
             if (messageType == RetriesMessageType)
             {
-                store.Store(message.Entries, instanceId, new EndpointMessageType(instanceId.EndpointName, message.TagValue));
+                store.Store(message.Entries, instanceId, new EndpointMessageType(instanceId.EndpointName, enclosedMessageTypes: message.TagValue));
             }
 
             return Task.CompletedTask;

src/ServiceControl.Monitoring/Timings/TaggedLongValueOccurrenceHandler.cs

@@ -16,7 +16,7 @@ public TaggedLongValueOccurrenceHandler(ProcessingTimeStore processingTimeStore,
         public Task Handle(TaggedLongValueOccurrence message, IMessageHandlerContext context)
         {
             var instanceId = EndpointInstanceId.From(context.MessageHeaders);
-            var messageType = new EndpointMessageType(instanceId.EndpointName, message.TagValue);
+            var messageType = new EndpointMessageType(instanceId.EndpointName, enclosedMessageTypes: message.TagValue);
 
             var metricType = context.MessageHeaders[MetricHeaders.MetricType];