/*
* 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 com.facebook.presto.jdbc.internal.netty.handler.codec.serialization;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.OutputStream;
import java.util.concurrent.atomic.AtomicReference;
import com.facebook.presto.jdbc.internal.netty.buffer.ChannelBuffer;
import com.facebook.presto.jdbc.internal.netty.buffer.ChannelBufferFactory;
import com.facebook.presto.jdbc.internal.netty.buffer.ChannelBufferOutputStream;
import com.facebook.presto.jdbc.internal.netty.buffer.ChannelBuffers;
import com.facebook.presto.jdbc.internal.netty.channel.Channel;
import com.facebook.presto.jdbc.internal.netty.channel.ChannelHandlerContext;
import com.facebook.presto.jdbc.internal.netty.handler.codec.oneone.OneToOneEncoder;
/**
* An encoder which serializes a Java object into a {@link ChannelBuffer}
* (interoperability version).
* <p>
* This encoder is interoperable with the standard Java object streams such as
* {@link ObjectInputStream} and {@link ObjectOutputStream}.
*/
public class CompatibleObjectEncoder extends OneToOneEncoder {
private final AtomicReference<ChannelBuffer> buffer =
new AtomicReference<ChannelBuffer>();
private final int resetInterval;
private volatile ObjectOutputStream oout;
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 Object encode(ChannelHandlerContext context, Channel channel, Object msg) throws Exception {
ChannelBuffer buffer = buffer(context);
ObjectOutputStream oout = this.oout;
if (resetInterval != 0) {
// Resetting will prevent OOM on the receiving side.
writtenObjects ++;
if (writtenObjects % resetInterval == 0) {
oout.reset();
// Also discard the byproduct to avoid OOM on the sending side.
buffer.discardReadBytes();
}
}
oout.writeObject(msg);
oout.flush();
ChannelBuffer encoded = buffer.readBytes(buffer.readableBytes());
return encoded;
}
private ChannelBuffer buffer(ChannelHandlerContext ctx) throws Exception {
ChannelBuffer buf = buffer.get();
if (buf == null) {
ChannelBufferFactory factory = ctx.getChannel().getConfig().getBufferFactory();
buf = ChannelBuffers.dynamicBuffer(factory);
if (buffer.compareAndSet(null, buf)) {
boolean success = false;
try {
oout = newObjectOutputStream(new ChannelBufferOutputStream(buf));
success = true;
} finally {
if (!success) {
oout = null;
}
}
} else {
buf = buffer.get();
}
}
return buf;
}
}