org.jboss.netty.handler.ssl.SslBufferPool Maven / Gradle / Ivy
/*
* Copyright 2009 Red Hat, Inc.
*
* Red Hat 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 org.jboss.netty.handler.ssl;
import java.nio.ByteBuffer;
import javax.net.ssl.SSLEngine;
/**
* A {@link ByteBuffer} pool dedicated for {@link SslHandler} performance
* improvement.
*
* In most cases, you won't need to create a new pool instance because
* {@link SslHandler} has a default pool instance internally.
*
* The reason why {@link SslHandler} requires a buffer pool is because the
* current {@link SSLEngine} implementation always requires a 17KiB buffer for
* every 'wrap' and 'unwrap' operation. In most cases, the actual size of the
* required buffer is much smaller than that, and therefore allocating a 17KiB
* buffer for every 'wrap' and 'unwrap' operation wastes a lot of memory
* bandwidth, resulting in the application performance degradation.
*
* @author The Netty Project
* @author Trustin Lee
*
* @version $Rev: 2080 $, $Date: 2010-01-26 18:04:19 +0900 (Tue, 26 Jan 2010) $
*/
public class SslBufferPool {
// Add 1024 as a room for compressed data and another 1024 for Apache Harmony compatibility.
private static final int MAX_PACKET_SIZE = 16665 + 2048;
private static final int DEFAULT_POOL_SIZE = MAX_PACKET_SIZE * 1024;
private final ByteBuffer[] pool;
private final int maxBufferCount;
private int index;
/**
* Creates a new buffer pool whose size is {@code 18113536}, which can
* hold {@code 1024} buffers.
*/
public SslBufferPool() {
this(DEFAULT_POOL_SIZE);
}
/**
* Creates a new buffer pool.
*
* @param maxPoolSize the maximum number of bytes that this pool can hold
*/
public SslBufferPool(int maxPoolSize) {
if (maxPoolSize <= 0) {
throw new IllegalArgumentException("maxPoolSize: " + maxPoolSize);
}
int maxBufferCount = maxPoolSize / MAX_PACKET_SIZE;
if (maxPoolSize % MAX_PACKET_SIZE != 0) {
maxBufferCount ++;
}
pool = new ByteBuffer[maxBufferCount];
this.maxBufferCount = maxBufferCount;
}
/**
* Returns the maximum size of this pool in byte unit. The returned value
* can be somewhat different from what was specified in the constructor.
*/
public int getMaxPoolSize() {
return maxBufferCount * MAX_PACKET_SIZE;
}
/**
* Returns the number of bytes which were allocated but have not been
* acquired yet. You can estimate how optimal the specified maximum pool
* size is from this value. If it keeps returning {@code 0}, it means the
* pool is getting exhausted. If it keeps returns a unnecessarily big
* value, it means the pool is wasting the heap space.
*/
public synchronized int getUnacquiredPoolSize() {
return index * MAX_PACKET_SIZE;
}
synchronized ByteBuffer acquire() {
if (index == 0) {
return ByteBuffer.allocate(MAX_PACKET_SIZE);
} else {
return (ByteBuffer) pool[-- index].clear();
}
}
synchronized void release(ByteBuffer buffer) {
if (index < maxBufferCount) {
pool[index ++] = buffer;
}
}
}