Monitoring cannot process metrics for processed polymorphic messages

[ramonsmits]

Symptoms

Monitoring cannot process messages where the EnclosedMessageTypes value contains multiple values which results in excessive retries and results in rate limiting issues on some transports.

The received value is the value from NServiceBus.EnclosedMessageTypes which can contain multiple types.

This should resolve the issue that MonitoredEndpointMessageTypeParser.Parse receives the value with all types and results in the following log entry:

2023-08-14 10:19:48.5594|8|Warn|ServiceControl.Monitoring.Http.Diagrams.MonitoredEndpointMessageTypeParser|Error parsing message type: XXXX, YYY, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null;ZZZZ, YYY, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null.
System.IO.FileLoadException: The given assembly name or codebase was invalid. (Exception from HRESULT: 0x80131047)
   at System.Reflection.AssemblyName.nInit(RuntimeAssembly& assembly, Boolean forIntrospection, Boolean raiseResolveEvent)
   at System.Reflection.AssemblyName..ctor(String assemblyName)
   at ServiceControl.Monitoring.Http.Diagrams.MonitoredEndpointMessageTypeParser.Parse(String typeName) in /_/src/ServiceControl.Monitoring/Http/Diagrams/MonitoredEndpointMessageTypeParser.cs:line 31

Who's affected

Users that use ServiceControl Monitoring and that send polymorphic messages (messages that use inheritance).

Root cause

Monitoring cannot process messages when EnclosedMessageTypes contains multiple values

[danielmarbach]

I apologize for my inputs coming in with such big delays. I have a few absences this week. These are wild thoughts. I'm fairly new to this code.

The original stack trace showed the problem coming from MonitoredEndpointMessageTypeParser and now we have essentially multiple places where we have to incorporate the splitting logic. The parser itself already has to deal with endpoint message types and the controller can already deal with multiple message types

https://github.com/Particular/ServiceControl/blob/master/src/ServiceControl.Monitoring/Http/Diagrams/DiagramApiController.cs#L254-L258

I wonder if it would be better to consolidate things a bit to centralize the parsing and creation of EndpointMessageType and make the MonitoredEndpointMessageTypeParser rely on that type too. This would essentially make sure polymorphic message types are visualized as multiple message types. Polymorphic types are always separated by ; see https://github.com/Particular/NServiceBus/blob/f9a03dc930c20dc80b18034f824be51fc2adbacd/src/NServiceBus.Core/Unicast/Messages/MessageMetadata.cs#L62. The parser could take that into account. Core also seems to treat those polymorphic ones as individual ones in multiple places

https://github.com/Particular/NServiceBus/blob/master/src/NServiceBus.Core/Pipeline/Incoming/DeserializeMessageConnector.cs#L72-L97
https://github.com/Particular/NServiceBus/blob/master/src/NServiceBus.Core/Pipeline/Incoming/DeserializeMessageConnector.cs#L120-L126
https://github.com/Particular/NServiceBus/blob/master/src/NServiceBus.Core/Routing/UnicastPublishRouter.cs#L28-L30