content: /*
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements.  See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership.  The ASF licenses this file
   * to you under the Apache License, Version 2.0 (the
   * "License"); you may not use this file except in compliance
   * with the License.  You may obtain a copy of the License at
   *
   *     https://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package org.apache.avro.grpc;
  
  import org.apache.avro.Protocol;
  
  import java.lang.reflect.InvocationTargetException;
  import java.lang.reflect.Method;
  import java.util.Map;
  import java.util.logging.Level;
  import java.util.logging.Logger;
  
  import io.grpc.MethodDescriptor;
  import io.grpc.ServerServiceDefinition;
  import io.grpc.stub.ServerCalls;
  import io.grpc.stub.StreamObserver;
  
  /**
   * Provides components to set up a gRPC Server for Avro's IDL and serialization.
   */
  public abstract class AvroGrpcServer {
  
    private AvroGrpcServer() {
    }
  
    /**
     * Creates a {@link ServerServiceDefinition} for Avro Interface and its
     * implementation that can be passed a gRPC Server.
     *
     * @param iface Avro generated RPC service interface for which service defintion
     *              is created.
     * @param impl  Implementation of the service interface to be invoked for
     *              requests.
     * @return a new server service definition.
     */
    public static ServerServiceDefinition createServiceDefinition(Class iface, Object impl) {
      Protocol protocol = AvroGrpcUtils.getProtocol(iface);
      ServiceDescriptor serviceDescriptor = ServiceDescriptor.create(iface);
      ServerServiceDefinition.Builder serviceDefinitionBuilder = ServerServiceDefinition
          .builder(serviceDescriptor.getServiceName());
      Map<String, Protocol.Message> messages = protocol.getMessages();
      for (Method method : iface.getMethods()) {
        Protocol.Message msg = messages.get(method.getName());
        // setup a method handler only if corresponding message exists in avro protocol.
        if (msg != null) {
          UnaryMethodHandler methodHandler = msg.isOneWay() ? new OneWayUnaryMethodHandler(impl, method)
              : new UnaryMethodHandler(impl, method);
          serviceDefinitionBuilder.addMethod(
              serviceDescriptor.getMethod(method.getName(), MethodDescriptor.MethodType.UNARY),
              ServerCalls.asyncUnaryCall(methodHandler));
        }
      }
      return serviceDefinitionBuilder.build();
    }
  
    private static class UnaryMethodHandler implements ServerCalls.UnaryMethod<Object[], Object> {
      private final Object serviceImpl;
      private final Method method;
  
      UnaryMethodHandler(Object serviceImpl, Method method) {
        this.serviceImpl = serviceImpl;
        this.method = method;
      }
  
      @Override
      public void invoke(Object[] request, StreamObserver<Object> responseObserver) {
        Object methodResponse = null;
        try {
          methodResponse = method.invoke(getServiceImpl(), request);
        } catch (InvocationTargetException e) {
          methodResponse = e.getTargetException();
        } catch (Exception e) {
          methodResponse = e;
        }
        responseObserver.onNext(methodResponse);
        responseObserver.onCompleted();
      }
  
      public Method getMethod() {
        return method;
      }
  
      public Object getServiceImpl() {
        return serviceImpl;
      }
    }
  
    private static class OneWayUnaryMethodHandler extends UnaryMethodHandler {
      private static final Logger LOG = Logger.getLogger(OneWayUnaryMethodHandler.class.getName());
  
      OneWayUnaryMethodHandler(Object serviceImpl, Method method) {
        super(serviceImpl, method);
      }
  
      @Override
      public void invoke(Object[] request, StreamObserver<Object> responseObserver) {
        // first respond back with a fixed void response in order for call to be
        // complete
        responseObserver.onNext(null);
        responseObserver.onCompleted();
        // process the rpc request
        try {
          getMethod().invoke(getServiceImpl(), request);
        } catch (Exception e) {
          Throwable cause = e;
          while (cause.getCause() != null && cause != cause.getCause()) {
            cause = cause.getCause();
          }
          LOG.log(Level.WARNING, "Error processing one-way rpc", cause);
        }
      }
    }
  }
  