Thanks for replying.
I did not quite understand the statement - "*It will respond
with Status.UNKNOWN and interceptors might get confused"* .
Let's say I do not have the try - catch in the purge() method and I have a
ServerInterceptor like below. Are you saying that the
statusException.getStatus()
in the below code may be Status.UNKNOWN sometime even if the
validator.validate() is throwing StatusRunTImeException with some different
Status. In that case statusException.getTrailers() can also be null or empty
?
public class ServerInterceptor implements io.grpc.ServerInterceptor {
public < ReqT, RespT > ServerCall.Listener < ReqT > interceptCall(
final ServerCall < ReqT, RespT > call,
final Metadata requestHeaders,
final ServerCallHandler < ReqT, RespT > next) {
return new SimpleForwardingServerCallListener < >
(next.startCall(grpcServerCall, requestHeaders)) {
public void onMessage(final ReqT message) {
try {
// do something
super.onMessage(message);
} catch (Exception e) {
handleException(ex);
throw ex;
}
}
// Similiar logic for onReady(), onHalfClose(), onComplete(),
// where in a try .. catch handleException() & throw ex
private void handleException(final Exception exception) {
if (exception instance of StatusRunTimeException statusException) {
val metadata = statusException.getTrailers();
log.error("Request failed with metadata={}", metadata,
statusException);
call.close(statusException.getStatus(),
ObjectUtils.defaultIfNull(metadata, new Metadata()));
return;
}
call.close(Status.UNKNOWN.withDescription(exception.getMessage()),
requestHeaders);
}
}
}
}
On Friday 12 April 2024 at 03:21:52 UTC+5:30 Eric Anderson wrote:
> If validator.validate() and service.purge() can throw, then you want a
> try-catch. You must call onCompleted() or onError() on the observer for the
> RPC to complete (and thus release its memory). gRPC does have some handling
> for exceptions thrown by the service method, but it is a worst-case backup.
> It will respond with Status.UNKNOWN and interceptors might get confused.
>
> If you are very concerned, you can catch exceptions from onNext(). In
> general code tends to assume onNext() won't throw (or rather, won't throw
> randomly; it will totally throw if you use it incorrectly, like calling it
> after onCompleted()). So that's why the Hello World example server doesn't
> have a try-catch.
>
> On Thu, Apr 11, 2024 at 1:55 PM Debraj <[email protected]> wrote:
>
>> If I have a code like below on a Java-based gRPC service
>>
>> @Override
>> public void purge(
>> final PurgeRequest request, final StreamObserver<PurgeResponse>
>> responseObserver) {
>> validator.validate(request);
>> responseObserver.onNext(service.purge(request));
>> responseObserver.onCompleted();
>> }
>>
>> Is it recommended that I catch the exception and call onError() like
>> below or it is not recommended? Is there any advantage of one approach over
>> the other?
>>
>> @Override
>> public void purge(
>> final PurgeRequest request, final StreamObserver<PurgeResponse>
>> responseObserver) {
>> try {
>> validator.validate(request);
>> responseObserver.onNext(gdprService.purge(request));
>> responseObserver.onCompleted();
>> } catch (final Exception e) {
>> log.error("Failed to purge {}", request, e);
>> responseObserver.onError(e);
>> }
>> }
>>
>>
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>>
>
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