org.apache.hadoop.io.BoundedByteArrayOutputStream.java Source code

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Here is the source code for org.apache.hadoop.io.BoundedByteArrayOutputStream.java

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/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements. See the NOTICE file distributed with this
 * work for additional information regarding copyright ownership. The ASF
 * 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.apache.hadoop.io;

import java.io.EOFException;
import java.io.IOException;
import java.io.OutputStream;

import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;

/**
 * A byte array backed output stream with a limit. The limit should be smaller
 * than the buffer capacity. The object can be reused through <code>reset</code>
 * API and choose different limits in each round.
 */
@InterfaceAudience.LimitedPrivate({ "HDFS", "MapReduce" })
@InterfaceStability.Unstable
public class BoundedByteArrayOutputStream extends OutputStream {
    private byte[] buffer;
    private int startOffset;
    private int limit;
    private int currentPointer;

    /**
     * Create a BoundedByteArrayOutputStream with the specified
     * capacity
     * @param capacity The capacity of the underlying byte array
     */
    public BoundedByteArrayOutputStream(int capacity) {
        this(capacity, capacity);
    }

    /**
     * Create a BoundedByteArrayOutputStream with the specified
     * capacity and limit.
     * @param capacity The capacity of the underlying byte array
     * @param limit The maximum limit upto which data can be written
     */
    public BoundedByteArrayOutputStream(int capacity, int limit) {
        this(new byte[capacity], 0, limit);
    }

    protected BoundedByteArrayOutputStream(byte[] buf, int offset, int limit) {
        resetBuffer(buf, offset, limit);
    }

    protected void resetBuffer(byte[] buf, int offset, int limit) {
        int capacity = buf.length - offset;
        if ((capacity < limit) || (capacity | limit) < 0) {
            throw new IllegalArgumentException("Invalid capacity/limit");
        }
        this.buffer = buf;
        this.startOffset = offset;
        this.currentPointer = offset;
        this.limit = offset + limit;
    }

    @Override
    public void write(int b) throws IOException {
        if (currentPointer >= limit) {
            throw new EOFException("Reaching the limit of the buffer.");
        }
        buffer[currentPointer++] = (byte) b;
    }

    @Override
    public void write(byte b[], int off, int len) throws IOException {
        if ((off < 0) || (off > b.length) || (len < 0) || ((off + len) > b.length) || ((off + len) < 0)) {
            throw new IndexOutOfBoundsException();
        } else if (len == 0) {
            return;
        }

        if (currentPointer + len > limit) {
            throw new EOFException("Reach the limit of the buffer");
        }

        System.arraycopy(b, off, buffer, currentPointer, len);
        currentPointer += len;
    }

    /**
     * Reset the limit 
     * @param newlim New Limit
     */
    public void reset(int newlim) {
        if (newlim > (buffer.length - startOffset)) {
            throw new IndexOutOfBoundsException("Limit exceeds buffer size");
        }
        this.limit = newlim;
        this.currentPointer = startOffset;
    }

    /** Reset the buffer */
    public void reset() {
        this.limit = buffer.length - startOffset;
        this.currentPointer = startOffset;
    }

    /** Return the current limit */
    public int getLimit() {
        return limit;
    }

    /** Returns the underlying buffer.
     *  Data is only valid to {@link #size()}.
     */
    public byte[] getBuffer() {
        return buffer;
    }

    /** Returns the length of the valid data 
     * currently in the buffer.
     */
    public int size() {
        return currentPointer - startOffset;
    }

    public int available() {
        return limit - currentPointer;
    }
}