/*
* Copyright 2011 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.buffer;
import java.lang.ref.ReferenceQueue;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
/**
* A {@link ChannelBufferFactory} which pre-allocates a large chunk of direct
* buffer and returns its slice on demand. Direct buffers are reclaimed via
* {@link ReferenceQueue} in most JDK implementations, and therefore they are
* deallocated less efficiently than an ordinary heap buffer. Consequently,
* a user will get {@link OutOfMemoryError} when one tries to allocate small
* direct buffers more often than the GC throughput of direct buffers, which
* is much lower than the GC throughput of heap buffers. This factory avoids
* this problem by allocating a large chunk of pre-allocated direct buffer and
* reducing the number of the garbage collected internal direct buffer objects.
*/
public class DirectChannelBufferFactory extends AbstractChannelBufferFactory {
private static final DirectChannelBufferFactory INSTANCE_BE =
new DirectChannelBufferFactory(ByteOrder.BIG_ENDIAN);
private static final DirectChannelBufferFactory INSTANCE_LE =
new DirectChannelBufferFactory(ByteOrder.LITTLE_ENDIAN);
public static ChannelBufferFactory getInstance() {
return INSTANCE_BE;
}
public static ChannelBufferFactory getInstance(ByteOrder defaultEndianness) {
if (defaultEndianness == ByteOrder.BIG_ENDIAN) {
return INSTANCE_BE;
} else if (defaultEndianness == ByteOrder.LITTLE_ENDIAN) {
return INSTANCE_LE;
} else if (defaultEndianness == null) {
throw new NullPointerException("defaultEndianness");
} else {
throw new IllegalStateException("Should not reach here");
}
}
private final Object bigEndianLock = new Object();
private final Object littleEndianLock = new Object();
private final int preallocatedBufferCapacity;
private ChannelBuffer preallocatedBigEndianBuffer;
private int preallocatedBigEndianBufferPosition;
private ChannelBuffer preallocatedLittleEndianBuffer;
private int preallocatedLittleEndianBufferPosition;
/**
* Creates a new factory whose default {@link ByteOrder} is
* {@link ByteOrder#BIG_ENDIAN}.
*/
public DirectChannelBufferFactory() {
this(ByteOrder.BIG_ENDIAN);
}
/**
* Creates a new factory whose default {@link ByteOrder} is
* {@link ByteOrder#BIG_ENDIAN}.
*/
public DirectChannelBufferFactory(int preallocatedBufferCapacity) {
this(ByteOrder.BIG_ENDIAN, preallocatedBufferCapacity);
}
/**
* Creates a new factory with the specified default {@link ByteOrder}.
*
* @param defaultOrder the default {@link ByteOrder} of this factory
*/
public DirectChannelBufferFactory(ByteOrder defaultOrder) {
this(defaultOrder, 1048576);
}
/**
* Creates a new factory with the specified default {@link ByteOrder}.
*
* @param defaultOrder the default {@link ByteOrder} of this factory
*/
public DirectChannelBufferFactory(ByteOrder defaultOrder, int preallocatedBufferCapacity) {
super(defaultOrder);
if (preallocatedBufferCapacity <= 0) {
throw new IllegalArgumentException(
"preallocatedBufferCapacity must be greater than 0: " + preallocatedBufferCapacity);
}
this.preallocatedBufferCapacity = preallocatedBufferCapacity;
}
public ChannelBuffer getBuffer(ByteOrder order, int capacity) {
if (order == null) {
throw new NullPointerException("order");
}
if (capacity < 0) {
throw new IllegalArgumentException("capacity: " + capacity);
}
if (capacity == 0) {
return ChannelBuffers.EMPTY_BUFFER;
}
if (capacity >= preallocatedBufferCapacity) {
return ChannelBuffers.directBuffer(order, capacity);
}
ChannelBuffer slice;
if (order == ByteOrder.BIG_ENDIAN) {
slice = allocateBigEndianBuffer(capacity);
} else {
slice = allocateLittleEndianBuffer(capacity);
}
slice.clear();
return slice;
}
public ChannelBuffer getBuffer(ByteOrder order, byte[] array, int offset, int length) {
if (array == null) {
throw new NullPointerException("array");
}
if (offset < 0) {
throw new IndexOutOfBoundsException("offset: " + offset);
}
if (length == 0) {
return ChannelBuffers.EMPTY_BUFFER;
}
if (offset + length > array.length) {
throw new IndexOutOfBoundsException("length: " + length);
}
ChannelBuffer buf = getBuffer(order, length);
buf.writeBytes(array, offset, length);
return buf;
}
public ChannelBuffer getBuffer(ByteBuffer nioBuffer) {
if (!nioBuffer.isReadOnly() && nioBuffer.isDirect()) {
return ChannelBuffers.wrappedBuffer(nioBuffer);
}
ChannelBuffer buf = getBuffer(nioBuffer.order(), nioBuffer.remaining());
int pos = nioBuffer.position();
buf.writeBytes(nioBuffer);
nioBuffer.position(pos);
return buf;
}
private ChannelBuffer allocateBigEndianBuffer(int capacity) {
ChannelBuffer slice;
synchronized (bigEndianLock) {
if (preallocatedBigEndianBuffer == null) {
preallocatedBigEndianBuffer = ChannelBuffers.directBuffer(ByteOrder.BIG_ENDIAN, preallocatedBufferCapacity);
slice = preallocatedBigEndianBuffer.slice(0, capacity);
preallocatedBigEndianBufferPosition = capacity;
} else if (preallocatedBigEndianBuffer.capacity() - preallocatedBigEndianBufferPosition >= capacity) {
slice = preallocatedBigEndianBuffer.slice(preallocatedBigEndianBufferPosition, capacity);
preallocatedBigEndianBufferPosition += capacity;
} else {
preallocatedBigEndianBuffer = ChannelBuffers.directBuffer(ByteOrder.BIG_ENDIAN, preallocatedBufferCapacity);
slice = preallocatedBigEndianBuffer.slice(0, capacity);
preallocatedBigEndianBufferPosition = capacity;
}
}
return slice;
}
private ChannelBuffer allocateLittleEndianBuffer(int capacity) {
ChannelBuffer slice;
synchronized (littleEndianLock) {
if (preallocatedLittleEndianBuffer == null) {
preallocatedLittleEndianBuffer = ChannelBuffers.directBuffer(ByteOrder.LITTLE_ENDIAN, preallocatedBufferCapacity);
slice = preallocatedLittleEndianBuffer.slice(0, capacity);
preallocatedLittleEndianBufferPosition = capacity;
} else if (preallocatedLittleEndianBuffer.capacity() - preallocatedLittleEndianBufferPosition >= capacity) {
slice = preallocatedLittleEndianBuffer.slice(preallocatedLittleEndianBufferPosition, capacity);
preallocatedLittleEndianBufferPosition += capacity;
} else {
preallocatedLittleEndianBuffer = ChannelBuffers.directBuffer(ByteOrder.LITTLE_ENDIAN, preallocatedBufferCapacity);
slice = preallocatedLittleEndianBuffer.slice(0, capacity);
preallocatedLittleEndianBufferPosition = capacity;
}
}
return slice;
}
}