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
   *
   *     http://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.bookkeeper.common.grpc.proxy;
  
  import io.grpc.CallOptions;
  import io.grpc.Channel;
  import io.grpc.ClientCall;
  import io.grpc.Metadata;
  import io.grpc.ServerCall;
  import io.grpc.ServerCall.Listener;
  import io.grpc.ServerCallHandler;
  
  /**
   * Abstract server call handler.
   */
  class ProxyServerCallHandler<ReqT, RespT> implements ServerCallHandler<ReqT, RespT> {
  
      private final ChannelFinder finder;
      private final CallOptions callOptions;
  
      ProxyServerCallHandler(ChannelFinder finder,
                             CallOptions callOptions) {
          this.finder = finder;
          this.callOptions = callOptions;
      }
  
      @Override
      public Listener<ReqT> startCall(ServerCall<ReqT, RespT> serverCall, Metadata headers) {
          Channel channel = finder.findChannel(serverCall, headers);
          ClientCall<ReqT, RespT> clientCall = channel.newCall(
              serverCall.getMethodDescriptor(), callOptions);
          ProxyCall<ReqT, RespT> proxyCall = new ProxyCall<>(
              serverCall,
              clientCall);
          clientCall.start(proxyCall.getClientCallListener(), headers);
          serverCall.request(1);
          clientCall.request(1);
          return proxyCall.getServerCallListener();
      }
  }
  