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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.compression;
17  
18  import io.netty.buffer.ByteBuf;
19  import io.netty.channel.ChannelFuture;
20  import io.netty.channel.ChannelPromise;
21  import io.netty.handler.codec.MessageToByteEncoder;
22  
23  /**
24   * Compresses a {@link ByteBuf} using the deflate algorithm.
25   */
26  public abstract class ZlibEncoder extends MessageToByteEncoder<ByteBuf> {
27  
28      protected ZlibEncoder() {
29          super(false);
30      }
31  
32      /**
33       * Returns {@code true} if and only if the end of the compressed stream
34       * has been reached.
35       */
36      public abstract boolean isClosed();
37  
38      /**
39       * Close this {@link ZlibEncoder} and so finish the encoding.
40       *
41       * The returned {@link ChannelFuture} will be notified once the
42       * operation completes.
43       */
44      public abstract ChannelFuture close();
45  
46      /**
47       * Close this {@link ZlibEncoder} and so finish the encoding.
48       * The given {@link ChannelFuture} will be notified once the operation
49       * completes and will also be returned.
50       */
51      public abstract ChannelFuture close(ChannelPromise promise);
52  
53  }