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.ClientCall;
  import io.grpc.Metadata;
  import io.grpc.ServerCall;
  import io.grpc.Status;
  import lombok.Getter;
  
  /**
   * Proxy grpc calls.
   */
  @Getter
  class ProxyCall<ReqT, RespT> {
  
      private final RequestProxy serverCallListener;
      private final ResponseProxy clientCallListener;
  
      ProxyCall(ServerCall<ReqT, RespT> serverCall,
                ClientCall<ReqT, RespT> clientCall) {
          this.serverCallListener = new RequestProxy(clientCall);
          this.clientCallListener = new ResponseProxy(serverCall);
      }
  
      /**
       * Request proxy to delegate client call.
       */
      private class RequestProxy extends ServerCall.Listener<ReqT> {
  
          private final ClientCall<ReqT, ?> clientCall;
          private boolean needToRequest;
  
          public RequestProxy(ClientCall<ReqT, ?> clientCall) {
              this.clientCall = clientCall;
          }
  
          @Override
          public void onMessage(ReqT message) {
              clientCall.sendMessage(message);
              synchronized (this) {
                  if (clientCall.isReady()) {
                      clientCallListener.serverCall.request(1);
                  } else {
                      needToRequest = true;
                  }
              }
          }
  
          @Override
          public void onHalfClose() {
              clientCall.halfClose();
          }
  
          @Override
          public void onCancel() {
              clientCall.cancel("Server cancelled", null);
          }
  
          @Override
          public void onReady() {
              clientCallListener.onServerReady();
          }
  
          synchronized void onClientReady() {
              if (needToRequest) {
                  clientCallListener.serverCall.request(1);
                  needToRequest = false;
              }
          }
  
      }
  
      /**
       * Response proxy to delegate server call.
       */
      private class ResponseProxy extends ClientCall.Listener<RespT> {
  
          private final ServerCall<?, RespT> serverCall;
          private boolean needToRequest;
  
          public ResponseProxy(ServerCall<?, RespT> serverCall) {
              this.serverCall = serverCall;
          }
  
          @Override
          public void onHeaders(Metadata headers) {
              serverCall.sendHeaders(headers);
          }
  
          @Override
          public void onMessage(RespT message) {
              serverCall.sendMessage(message);
              synchronized (this) {
                  if (serverCall.isReady()) {
                      serverCallListener.clientCall.request(1);
                  } else {
                      needToRequest = true;
                  }
              }
          }
  
          @Override
          public void onClose(Status status, Metadata trailers) {
              serverCall.close(status, trailers);
          }
  
          @Override
          public void onReady() {
              serverCallListener.onClientReady();
          }
  
          synchronized void onServerReady() {
              if (needToRequest) {
                  serverCallListener.clientCall.request(1);
                  needToRequest = false;
              }
          }
  
      }
  
  }
  