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   /*
    * Copyright 2020 The Netty Project
    *
    * The Netty Project 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 io.netty.example.http2.helloworld.frame.client;
  
  import io.netty.channel.ChannelHandlerContext;
  import io.netty.channel.SimpleChannelInboundHandler;
  import io.netty.handler.codec.http2.Http2DataFrame;
  import io.netty.handler.codec.http2.Http2HeadersFrame;
  import io.netty.handler.codec.http2.Http2StreamFrame;
  
  import java.util.concurrent.CountDownLatch;
  import java.util.concurrent.TimeUnit;
  
  /**
   * Handles HTTP/2 stream frame responses. This is a useful approach if you specifically want to check
   * the main HTTP/2 response DATA/HEADERs, but in this example it's used purely to see whether
   * our request (for a specific stream id) has had a final response (for that same stream id).
   */
  public final class Http2ClientStreamFrameResponseHandler extends SimpleChannelInboundHandler<Http2StreamFrame> {
  
      private final CountDownLatch latch = new CountDownLatch(1);
  
      @Override
      protected void channelRead0(ChannelHandlerContext ctx, Http2StreamFrame msg) throws Exception {
          System.out.println("Received HTTP/2 'stream' frame: " + msg);
  
          // isEndStream() is not from a common interface, so we currently must check both
          if (msg instanceof Http2DataFrame && ((Http2DataFrame) msg).isEndStream()) {
              latch.countDown();
          } else if (msg instanceof Http2HeadersFrame && ((Http2HeadersFrame) msg).isEndStream()) {
              latch.countDown();
          }
      }
  
      /**
       * Waits for the latch to be decremented (i.e. for an end of stream message to be received), or for
       * the latch to expire after 5 seconds.
       * @return true if a successful HTTP/2 end of stream message was received.
       */
      public boolean responseSuccessfullyCompleted() {
          try {
              return latch.await(5, TimeUnit.SECONDS);
          } catch (InterruptedException ie) {
              System.err.println("Latch exception: " + ie.getMessage());
              return false;
          }
      }
  
  }