FastByteArrayOutputStream.java

/*
 * Copyright (c) 2008, Harald Kuhr
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 *     * Neither the name "TwelveMonkeys" nor the
 *       names of its contributors may be used to endorse or promote products
 *       derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

package com.twelvemonkeys.io;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.io.ByteArrayInputStream;

/**
 * An unsynchronized {@code ByteArrayOutputStream} implementation. This version
 * also has a constructor that lets you create a stream with initial content.
 * <p/>
 *
 * @author <a href="mailto:harald.kuhr@gmail.com">Harald Kuhr</a>
 * @version $Id: FastByteArrayOutputStream.java#2 $
 */
// TODO: Performance test of a stream impl that uses list of fixed size blocks, rather than contiguous block 
public final class FastByteArrayOutputStream extends ByteArrayOutputStream {
    /** Max grow size (unless if writing more than this amount of bytes) */
    protected int maxGrowSize = 1024 * 1024; // 1 MB

    /**
     * Creates a {@code ByteArrayOutputStream} with the given initial buffer
     * size.
     *
     * @param pSize initial buffer size
     */
    public FastByteArrayOutputStream(int pSize) {
        super(pSize);
    }

    /**
     * Creates a {@code ByteArrayOutputStream} with the given initial content.
     * <p/>
     * Note that the buffer is not cloned, for maximum performance.
     *
     * @param pBuffer initial buffer
     */
    public FastByteArrayOutputStream(byte[] pBuffer) {
        super(0); // Don't allocate array
        buf = pBuffer;
        count = pBuffer.length;
    }

    @Override
    public void write(byte pBytes[], int pOffset, int pLength) {
        if ((pOffset < 0) || (pOffset > pBytes.length) || (pLength < 0) ||
                ((pOffset + pLength) > pBytes.length) || ((pOffset + pLength) < 0)) {
            throw new IndexOutOfBoundsException();
        }
        else if (pLength == 0) {
            return;
        }

        int newCount = count + pLength;
        growIfNeeded(newCount);
        System.arraycopy(pBytes, pOffset, buf, count, pLength);
        count = newCount;
    }

    @Override
    public void write(int pByte) {
        int newCount = count + 1;
        growIfNeeded(newCount);
        buf[count] = (byte) pByte;
        count = newCount;
    }

    private void growIfNeeded(int pNewCount) {
        if (pNewCount > buf.length) {
            int newSize = Math.max(Math.min(buf.length << 1, buf.length + maxGrowSize), pNewCount);
            byte newBuf[] = new byte[newSize];
            System.arraycopy(buf, 0, newBuf, 0, count);
            buf = newBuf;
        }
    }

    // Non-synchronized version of writeTo
    @Override
    public void writeTo(OutputStream pOut) throws IOException {
        pOut.write(buf, 0, count);
    }

    // Non-synchronized version of toByteArray
    @Override
    public byte[] toByteArray() {
        byte newBuf[] = new byte[count];
        System.arraycopy(buf, 0, newBuf, 0, count);

        return newBuf;
    }

    /**
     * Creates a {@code ByteArrayInputStream} that reads directly from this
     * {@code FastByteArrayOutputStream}'s byte buffer.
     * The buffer is not cloned, for maximum performance.
     * <p/>
     * Note that care needs to be taken to avoid writes to
     * this output stream after the input stream is created.
     * Failing to do so, may result in unpredictable behaviour.
     *
     * @return a new {@code ByteArrayInputStream}, reading from this stream's buffer.
     */
    public ByteArrayInputStream createInputStream() {
        return new ByteArrayInputStream(buf, 0, count);
    }
}