Boggy
Boggy
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Created by Boggy on 7/12/2024 in #help
C# event subscription in the context of a gRPC stream
I'm trying to understand why my code is not working in the context of a gRPC streaming method. 
C#
public override async Task Stream(...)
{
   await _myService.DoSomeSubscription();
}
C#
public override async Task Stream(...)
{
   await _myService.DoSomeSubscription();
}
When calling DoSomeSubscription() from a singleton service, not a gRPC server service, the code works as expected. The issue is that MyService (singleton) behaves differently if injected into a gRPC service vs a normal singleton service. I narrowed down the issue to the event subscription itself. 
C#
public Task DoSomeSubscription()
{
   return Task.Run(() =>
   {
       // my object is also injected as a singleton;
       // the subscription looks like it's not made
       myObj.Changed += (c) =>
       {
          Console.WriteLine(c);
       };
       
       // this triggers the event, but it never enters the subscription above if the method is called from the gRPC service
       // it enters from the normal singleton service
       myObj.Change(3);
   };
}
C#
public Task DoSomeSubscription()
{
   return Task.Run(() =>
   {
       // my object is also injected as a singleton;
       // the subscription looks like it's not made
       myObj.Changed += (c) =>
       {
          Console.WriteLine(c);
       };
       
       // this triggers the event, but it never enters the subscription above if the method is called from the gRPC service
       // it enters from the normal singleton service
       myObj.Change(3);
   };
}
I'm not sure what the exact issue is,but my guess is that gRPC somehow works differently behing the scenes, since it has a different threading model.
4 replies