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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.marshalling;
17  
18  import io.netty.channel.Channel;
19  import io.netty.channel.ChannelHandler;
20  import io.netty.channel.ChannelHandlerContext;
21  import io.netty.util.Attribute;
22  import io.netty.util.AttributeKey;
23  import org.jboss.marshalling.MarshallerFactory;
24  import org.jboss.marshalling.MarshallingConfiguration;
25  import org.jboss.marshalling.Unmarshaller;
26  
27  /**
28   * {@link UnmarshallerProvider} which store a reference to the {@link Unmarshaller} in the
29   * {@link ChannelHandlerContext} via the {@link ChannelHandlerContext#attr(AttributeKey)}
30   * method. So the same {@link Unmarshaller} will be used during the life-time of a {@link Channel}
31   * for the {@link ChannelHandler}'s {@link ChannelHandlerContext}.
32   *
33   *
34   */
35  public class ContextBoundUnmarshallerProvider extends DefaultUnmarshallerProvider {
36  
37      private static final AttributeKey<Unmarshaller> UNMARSHALLER = AttributeKey.valueOf(
38              ContextBoundUnmarshallerProvider.class, "UNMARSHALLER");
39  
40      public ContextBoundUnmarshallerProvider(MarshallerFactory factory, MarshallingConfiguration config) {
41          super(factory, config);
42      }
43  
44      @Override
45      public Unmarshaller getUnmarshaller(ChannelHandlerContext ctx) throws Exception {
46          Attribute<Unmarshaller> attr = ctx.attr(UNMARSHALLER);
47          Unmarshaller unmarshaller = attr.get();
48          if (unmarshaller == null) {
49              unmarshaller = super.getUnmarshaller(ctx);
50              attr.set(unmarshaller);
51          }
52          return unmarshaller;
53      }
54  }