org.jboss.netty.buffer.DirectChannelBufferFactory Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of netty
The Netty project is an effort to provide an asynchronous event-driven network application framework and tools for rapid development of maintainable high performance and high scalability protocol servers and clients. In other words, Netty is a NIO client server framework which enables quick and easy development of network applications such as protocol servers and clients. It greatly simplifies and streamlines network programming such as TCP and UDP socket server.
There is a newer version: 3.2.10.Final
Show newest version
/*
 * 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.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.
 *
 * @author The Netty Project
 * @author Trustin Lee
 * @version $Rev: 2293 $, $Date: 2010-06-01 17:38:51 +0900 (Tue, 01 Jun 2010) $
 */
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 = null;
    private int preallocatedBigEndianBufferPosition;
    private ChannelBuffer preallocatedLittleEndianBuffer = null;
    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;
    }
}