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 org.jboss.netty.handler.codec.serialization;
17
18 import java.io.ObjectInputStream;
19 import java.io.ObjectOutputStream;
20 import java.io.OutputStream;
21 import java.util.concurrent.atomic.AtomicReference;
22
23 import org.jboss.netty.buffer.ChannelBuffer;
24 import org.jboss.netty.buffer.ChannelBufferFactory;
25 import org.jboss.netty.buffer.ChannelBufferOutputStream;
26 import org.jboss.netty.buffer.ChannelBuffers;
27 import org.jboss.netty.channel.Channel;
28 import org.jboss.netty.channel.ChannelHandlerContext;
29 import org.jboss.netty.handler.codec.oneone.OneToOneEncoder;
30
31 /**
32 * An encoder which serializes a Java object into a {@link ChannelBuffer}
33 * (interoperability version).
34 * <p>
35 * This encoder is interoperable with the standard Java object streams such as
36 * {@link ObjectInputStream} and {@link ObjectOutputStream}.
37 */
38 public class CompatibleObjectEncoder extends OneToOneEncoder {
39
40 private final AtomicReference<ChannelBuffer> buffer =
41 new AtomicReference<ChannelBuffer>();
42 private final int resetInterval;
43 private volatile ObjectOutputStream oout;
44 private int writtenObjects;
45
46 /**
47 * Creates a new instance with the reset interval of {@code 16}.
48 */
49 public CompatibleObjectEncoder() {
50 this(16); // Reset at every sixteen writes
51 }
52
53 /**
54 * Creates a new instance.
55 *
56 * @param resetInterval
57 * the number of objects between {@link ObjectOutputStream#reset()}.
58 * {@code 0} will disable resetting the stream, but the remote
59 * peer will be at the risk of getting {@link OutOfMemoryError} in
60 * the long term.
61 */
62 public CompatibleObjectEncoder(int resetInterval) {
63 if (resetInterval < 0) {
64 throw new IllegalArgumentException(
65 "resetInterval: " + resetInterval);
66 }
67 this.resetInterval = resetInterval;
68 }
69
70 /**
71 * Creates a new {@link ObjectOutputStream} which wraps the specified
72 * {@link OutputStream}. Override this method to use a subclass of the
73 * {@link ObjectOutputStream}.
74 */
75 protected ObjectOutputStream newObjectOutputStream(OutputStream out) throws Exception {
76 return new ObjectOutputStream(out);
77 }
78
79 @Override
80 protected Object encode(ChannelHandlerContext context, Channel channel, Object msg) throws Exception {
81 ChannelBuffer buffer = buffer(context);
82 ObjectOutputStream oout = this.oout;
83 if (resetInterval != 0) {
84 // Resetting will prevent OOM on the receiving side.
85 writtenObjects ++;
86 if (writtenObjects % resetInterval == 0) {
87 oout.reset();
88
89 // Also discard the byproduct to avoid OOM on the sending side.
90 buffer.discardReadBytes();
91 }
92 }
93 oout.writeObject(msg);
94 oout.flush();
95
96 ChannelBuffer encoded = buffer.readBytes(buffer.readableBytes());
97 return encoded;
98 }
99
100 private ChannelBuffer buffer(ChannelHandlerContext ctx) throws Exception {
101 ChannelBuffer buf = buffer.get();
102 if (buf == null) {
103 ChannelBufferFactory factory = ctx.getChannel().getConfig().getBufferFactory();
104 buf = ChannelBuffers.dynamicBuffer(factory);
105 if (buffer.compareAndSet(null, buf)) {
106 boolean success = false;
107 try {
108 oout = newObjectOutputStream(new ChannelBufferOutputStream(buf));
109 success = true;
110 } finally {
111 if (!success) {
112 oout = null;
113 }
114 }
115 } else {
116 buf = buffer.get();
117 }
118 }
119 return buf;
120 }
121 }
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