Detecting unimplemented method for server side streaming RPC (C++)

[Robert Bielik]

I have a server side streaming RPC, that might return an error directly, like UNIMPLEMENTED or RESOURCE_EXHAUSTED, or work as expected 

at which point the client will hang on the reader->Read(...) method.

In the case of UNIMPLEMENTED, I can see that the call to the server is made when client gets a reader:

auto reader = service->Notifications(client_context, ...);

so it *should* be possible to get hold of that return value without calling the reader->Read(...) method ? But I cannot see how?

Regards

/Robert

[ncte...@google.com]

Does handling the UNIMPLEMENTED status in the Read(){} loop make your code harder to structure? I agree that an UNIMPLEMENTED will be known at the time to ClientReader creation, but I don't see why that can't be handled in the main loop, just as other error types are