org.jboss.netty.handler.ssl.SslBufferPool Maven / Gradle / Ivy
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/*
* 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 org.jboss.netty.handler.ssl;
import javax.net.ssl.SSLEngine;
import java.nio.ByteBuffer;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.atomic.AtomicInteger;
/**
* 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.
*/
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_ALIGNED = (OpenSslEngine.MAX_ENCRYPTED_PACKET_LENGTH / 128 + 1) * 128;
private static final int DEFAULT_POOL_SIZE = MAX_PACKET_SIZE_ALIGNED * 1024;
private final ByteBuffer preallocated;
private final BlockingQueue pool;
private final int maxBufferCount;
private final boolean allocateDirect;
/**
* The number of buffers allocated so far. Used only when {@link #preallocated} is null.
*/
private final AtomicInteger numAllocations;
/**
* Creates a new buffer pool whose size is {@code 19267584}, which can hold {@code 1024} buffers.
*/
public SslBufferPool() {
this(DEFAULT_POOL_SIZE);
}
/**
* Creates a new buffer pool whose size is {@code 19267584}, which can hold {@code 1024} buffers.
*
* @param preallocate {@code true} if and only if the buffers in this pool has to be pre-allocated
* at construction time
* @param allocateDirect {@code true} if and only if this pool has to allocate direct buffers.
*/
public SslBufferPool(boolean preallocate, boolean allocateDirect) {
this(DEFAULT_POOL_SIZE, preallocate, allocateDirect);
}
/**
* Creates a new buffer pool.
*
* @param maxPoolSize the maximum number of bytes that this pool can hold
*/
public SslBufferPool(int maxPoolSize) {
this(maxPoolSize, false, false);
}
/**
* Creates a new buffer pool.
*
* @param maxPoolSize the maximum number of bytes that this pool can hold
* @param preallocate {@code true} if and only if the buffers in this pool has to be pre-allocated
* at construction time
* @param allocateDirect {@code true} if and only if this pool has to allocate direct buffers.
*/
public SslBufferPool(int maxPoolSize, boolean preallocate, boolean allocateDirect) {
if (maxPoolSize <= 0) {
throw new IllegalArgumentException("maxPoolSize: " + maxPoolSize);
}
int maxBufferCount = maxPoolSize / MAX_PACKET_SIZE_ALIGNED;
if (maxPoolSize % MAX_PACKET_SIZE_ALIGNED != 0) {
maxBufferCount ++;
}
this.maxBufferCount = maxBufferCount;
this.allocateDirect = allocateDirect;
pool = new ArrayBlockingQueue(maxBufferCount);
if (preallocate) {
preallocated = allocate(maxBufferCount * MAX_PACKET_SIZE_ALIGNED);
numAllocations = null;
for (int i = 0; i < maxBufferCount; i ++) {
int pos = i * MAX_PACKET_SIZE_ALIGNED;
preallocated.clear().position(pos).limit(pos + MAX_PACKET_SIZE_ALIGNED);
pool.add(preallocated.slice());
}
} else {
preallocated = null;
numAllocations = new AtomicInteger();
}
}
/**
* 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_ALIGNED;
}
/**
* 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 int getUnacquiredPoolSize() {
return pool.size() * MAX_PACKET_SIZE_ALIGNED;
}
/**
* Acquire a new {@link ByteBuffer} out of the {@link SslBufferPool}
*
*/
public ByteBuffer acquireBuffer() {
ByteBuffer buf;
if (preallocated != null || numAllocations.get() >= maxBufferCount) {
boolean interrupted = false;
for (;;) {
try {
buf = pool.take();
break;
} catch (InterruptedException ignore) {
interrupted = true;
}
}
if (interrupted) {
Thread.currentThread().interrupt();
}
} else {
buf = pool.poll();
if (buf == null) {
// Note that we can allocate more buffers than maxBufferCount.
// We will discard the buffers allocated after numAllocations reached maxBufferCount in releaseBuffer().
numAllocations.incrementAndGet();
buf = allocate(OpenSslEngine.MAX_ENCRYPTED_PACKET_LENGTH);
}
}
buf.clear();
return buf;
}
/**
* Release a previous acquired {@link ByteBuffer}
*/
public void releaseBuffer(ByteBuffer buffer) {
pool.offer(buffer);
}
private ByteBuffer allocate(int capacity) {
if (allocateDirect) {
return ByteBuffer.allocateDirect(capacity);
} else {
return ByteBuffer.allocate(capacity);
}
}
}