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   /*
    * Copyright 2019 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.handler.codec.http2;
  
  import io.netty.util.internal.ObjectUtil;
  
  /**
   * Enforce a limit on the maximum number of consecutive empty DATA frames (without end_of_stream flag) that are allowed
   * before the connection will be closed.
   */
  final class Http2EmptyDataFrameConnectionDecoder extends DecoratingHttp2ConnectionDecoder {
  
      private final int maxConsecutiveEmptyFrames;
  
      Http2EmptyDataFrameConnectionDecoder(Http2ConnectionDecoder delegate, int maxConsecutiveEmptyFrames) {
          super(delegate);
          this.maxConsecutiveEmptyFrames = ObjectUtil.checkPositive(
                  maxConsecutiveEmptyFrames, "maxConsecutiveEmptyFrames");
      }
  
      @Override
      public void frameListener(Http2FrameListener listener) {
          if (listener != null) {
              super.frameListener(new Http2EmptyDataFrameListener(listener, maxConsecutiveEmptyFrames));
          } else {
              super.frameListener(null);
          }
      }
  
      @Override
      public Http2FrameListener frameListener() {
          Http2FrameListener frameListener = frameListener0();
          // Unwrap the original Http2FrameListener as we add this decoder under the hood.
          if (frameListener instanceof Http2EmptyDataFrameListener) {
              return ((Http2EmptyDataFrameListener) frameListener).listener;
          }
          return frameListener;
      }
  
      // Package-private for testing
      Http2FrameListener frameListener0() {
          return super.frameListener();
      }
  }