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1   /*
2    * Copyright 2012 The Netty Project
3    *
4    * The Netty Project licenses this file to you under the Apache License,
5    * version 2.0 (the "License"); you may not use this file except in compliance
6    * with the License. You may obtain a copy of the License at:
7    *
8    *   http://www.apache.org/licenses/LICENSE-2.0
9    *
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
12   * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
13   * License for the specific language governing permissions and limitations
14   * under the License.
15   */
16  package io.netty.handler.codec.spdy;
17  
18  import io.netty.channel.ChannelHandlerContext;
19  import io.netty.handler.codec.MessageToMessageCodec;
20  import io.netty.handler.codec.http.HttpMessage;
21  import io.netty.handler.codec.spdy.SpdyHttpHeaders.Names;
22  import io.netty.util.ReferenceCountUtil;
23  
24  import java.util.LinkedList;
25  import java.util.List;
26  import java.util.Queue;
27  
28  /**
29   * {@link MessageToMessageCodec} that takes care of adding the right {@link SpdyHttpHeaders.Names#STREAM_ID} to the
30   * {@link HttpMessage} if one is not present. This makes it possible to just re-use plan handlers current used
31   * for HTTP.
32   */
33  public class SpdyHttpResponseStreamIdHandler extends
34          MessageToMessageCodec<Object, HttpMessage> {
35      private static final Integer NO_ID = -1;
36      private final Queue<Integer> ids = new LinkedList<Integer>();
37  
38      @Override
39      public boolean acceptInboundMessage(Object msg) throws Exception {
40          return msg instanceof HttpMessage || msg instanceof SpdyRstStreamFrame;
41      }
42  
43      @Override
44      protected void encode(ChannelHandlerContext ctx, HttpMessage msg, List<Object> out) throws Exception {
45          Integer id = ids.poll();
46          if (id != null && id.intValue() != NO_ID && !msg.headers().contains(SpdyHttpHeaders.Names.STREAM_ID)) {
47              msg.headers().setInt(Names.STREAM_ID, id);
48          }
49  
50          out.add(ReferenceCountUtil.retain(msg));
51      }
52  
53      @Override
54      protected void decode(ChannelHandlerContext ctx, Object msg, List<Object> out) throws Exception {
55          if (msg instanceof HttpMessage) {
56              boolean contains = ((HttpMessage) msg).headers().contains(SpdyHttpHeaders.Names.STREAM_ID);
57              if (!contains) {
58                  ids.add(NO_ID);
59              } else {
60                  ids.add(((HttpMessage) msg).headers().getInt(Names.STREAM_ID));
61              }
62          } else if (msg instanceof SpdyRstStreamFrame) {
63              ids.remove(((SpdyRstStreamFrame) msg).streamId());
64          }
65  
66          out.add(ReferenceCountUtil.retain(msg));
67      }
68  }