Could not add interceptor(s) to `ProtoReflectionService`

[jyane]

What did you do?

Add interceptor(s) to ProtoReflectionService.

What did you expect to see?

ProtoReflectionService works with interceptor(s).

What did you see instead?

Got a NullPointerException or compilation error.

Problem

I ask a question on Gitter.
https://gitter.im/grpc/grpc?at=59b9090bcfeed2eb65033bad
and I have got a reply from @e.jona86.
https://gitter.im/grpc/grpc?at=59b9a7f9c101bc4e3ac3404a
I think it is not easy to fix. So I report an issue.

ProtoReflectionService needs a reference to Server via notifyOnBuild but it could not, because an intercepted service is an instance of ServerServiceDefinition.

I think it is consisting some problems (may not a bug or may not a problem) as below.

• ServerInterceptors#intercept binds a service and returns ServerServiceDefinition.
• ServerBuilder#addService doesn't add ServerServiceDefinition to notifyOnBuildList.
• ServerServiceDefinition doesn't implement InternalNotifyOnBuild.

Therefore, I could not add interceptor(s) to ProtoReflectionService.

[ejona86]

@ericgribkoff, were we aware of this limitation during the design?

[ericgribkoff]

@ejona86 No, I don't think so. This was an oversight on my part. I'll look into getting the mechanism working with server interceptors.

[ejona86]

As I mentioned in #3449, we could add a field of a method to run to ServerServiceDefinition as a replacement for InternalNotifyOnBuild.

Note: you may be able to use ServerBuilder.intercept() as a workaround. As long as you're okay with the interceptor applying to all services, that would work.

[jyane]

Thank you for your reply, it works. But I want to add interceptor(s) to each services.
I'm waiting for resolving this issue because it seems to be hard to resolve for me...