Cannot throw custome runtime exception inside clientinterceptor

[rezadhah]

Please answer these questions before submitting your issue.

What version of gRPC are you using?

1.4.0

What JVM are you using (java -version)?

1.8.0_144

What did you do?

If possible, provide a recipe for reproducing the error.

So i was trying to use ClientInterceptor by overiding onMessage(RespT message). So i'm trying to throw my custome runtime exception inside ForwaringClientCall.listener something like this

Field code;

@Override
public void onMessage(RespT message) {
    try {
        getCode = message.getClass().getMethod("getCode");
        getMessage = message.getClass().getMethod("getMessage");
        returnCode = (int) getCode.invoke(message);
        returnMessage = (String) getMessage.invoke(message);
     } catch (NoSuchMethodException | InvocationTargetException | IllegalAccessException e) {}
     
     if (returnCode != 200) {
          throw new CustomeRuntimeException(returnCode, returnMessage); // here
     }
     logger.info("{} fnished ...", methodName);
     super.onMessage(message);
}

What did you expect to see?

I excpect it will throw my custom exception

What did you see instead?

it always end inside inside this method catch (Throwable t) and it will end with statusruntimeexception cancel

@Override
public void messageRead(final InputStream message) {
  class MessageRead extends ContextRunnable {
    MessageRead() {
    super(context);
  }

  @Override
  public final void runInContext() {
   try {
       if (closed) {
          return;
   }
   try {
         observer.onMessage(method.parseResponse(message));
      } finally {
        message.close();
      }
    } catch (Throwable t) {
       Status status =
       Status.CANCELLED.withCause(t).withDescription("Failed to read message.");
       stream.cancel(status);
       close(status, new Metadata());
     }
  }
}

Thank you for your attention

[rezadhah]

Is it possible to throw my custom exception inside ClientInterceptor?

[carl-mastrangelo]

You can throw whatever you want, but we will always wrap it in a StatusRuntimeException or StatusException.

It will be set as the cause in the the Status.

[ejona86]

It's generally best not to throw within an interceptor. Instead call cancel() directly. Throwing should be more when there is a bug (so any exceptions from the reflection would probably be fine, but returnCode seems better for graceful handling.

[rezadhah]

Yes, i am currently in client team. We want to handle runtime exception by converting code (with http code standard) that server send as response because stacktrace thread server cannot be send to client. We have standard to use code and message to check what kind of error we get from server. So i thought that it can be handle with:

• via ClientInterceptor in onMessage method because that function will give the response and i can check it via reflection
• via aop, but i cannot target a pointcut to static final class (we use grpc + spring boot)
• dynamic proxy, and again it cannot be done because there is no interface on generated stub