/*
* Copyright 2012 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:
*
* http://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.serialization;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.ByteBufOutputStream;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.MessageToByteEncoder;
import io.netty.util.Attribute;
import io.netty.util.AttributeKey;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.OutputStream;
import java.io.Serializable;
/**
* An encoder which serializes a Java object into a {@link ByteBuf}
* (interoperability version).
* <p>
* This encoder is interoperable with the standard Java object streams such as
* {@link ObjectInputStream} and {@link ObjectOutputStream}.
*/
public class CompatibleObjectEncoder extends MessageToByteEncoder<Serializable> {
private static final AttributeKey<ObjectOutputStream> OOS =
AttributeKey.valueOf(CompatibleObjectEncoder.class.getName() + ".OOS");
private final int resetInterval;
private int writtenObjects;
/**
* Creates a new instance with the reset interval of {@code 16}.
*/
public CompatibleObjectEncoder() {
this(16); // Reset at every sixteen writes
}
/**
* Creates a new instance.
*
* @param resetInterval
* the number of objects between {@link ObjectOutputStream#reset()}.
* {@code 0} will disable resetting the stream, but the remote
* peer will be at the risk of getting {@link OutOfMemoryError} in
* the long term.
*/
public CompatibleObjectEncoder(int resetInterval) {
if (resetInterval < 0) {
throw new IllegalArgumentException(
"resetInterval: " + resetInterval);
}
this.resetInterval = resetInterval;
}
/**
* Creates a new {@link ObjectOutputStream} which wraps the specified
* {@link OutputStream}. Override this method to use a subclass of the
* {@link ObjectOutputStream}.
*/
protected ObjectOutputStream newObjectOutputStream(OutputStream out) throws Exception {
return new ObjectOutputStream(out);
}
@Override
protected void encode(ChannelHandlerContext ctx, Serializable msg, ByteBuf out) throws Exception {
Attribute<ObjectOutputStream> oosAttr = ctx.attr(OOS);
ObjectOutputStream oos = oosAttr.get();
if (oos == null) {
oos = newObjectOutputStream(new ByteBufOutputStream(out));
ObjectOutputStream newOos = oosAttr.setIfAbsent(oos);
if (newOos != null) {
oos = newOos;
}
}
synchronized (oos) {
if (resetInterval != 0) {
// Resetting will prevent OOM on the receiving side.
writtenObjects ++;
if (writtenObjects % resetInterval == 0) {
oos.reset();
}
}
oos.writeObject(msg);
oos.flush();
}
}
}