giraph-core/src/main/java/org/apache/giraph/utils/ExtendedByteArrayDataOutput.java

/*
 * 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.giraph.utils;

import java.io.ByteArrayOutputStream;
import java.io.DataOutput;
import java.io.DataOutputStream;
import java.io.IOException;
import java.util.Arrays;

/**
 * Adds some functionality to ByteArrayOutputStream,
 * such as an option to write int value over previously written data
 * and directly get the byte array.
 */
public class ExtendedByteArrayDataOutput extends ByteArrayOutputStream
    implements ExtendedDataOutput {
  /** Default number of bytes */
  private static final int DEFAULT_BYTES = 32;
  /** Internal data output */
  private final DataOutput dataOutput;

  /**
   * Uses the byte array provided or if null, use a default size
   *
   * @param buf Buffer to use
   */
  public ExtendedByteArrayDataOutput(byte[] buf) {
    if (buf == null) {
      this.buf = new byte[DEFAULT_BYTES];
    } else {
      this.buf = buf;
    }
    dataOutput = new DataOutputStream(this);
  }

  /**
   * Uses the byte array provided at the given pos
   *
   * @param buf Buffer to use
   * @param pos Position in the buffer to start writing from
   */
  public ExtendedByteArrayDataOutput(byte[] buf, int pos) {
    this(buf);
    this.count = pos;
  }

  /**
   * Creates a new byte array output stream. The buffer capacity is
   * initially 32 bytes, though its size increases if necessary.
   */
  public ExtendedByteArrayDataOutput() {
    this(DEFAULT_BYTES);
  }

  /**
   * Creates a new byte array output stream, with a buffer capacity of
   * the specified size, in bytes.
   *
   * @param size the initial size.
   * @exception  IllegalArgumentException if size is negative.
   */
  public ExtendedByteArrayDataOutput(int size) {
    if (size < 0) {
      throw new IllegalArgumentException("Negative initial size: " +
          size);
    }
    buf = new byte[size];
    dataOutput = new DataOutputStream(this);
  }

  @Override
  public void writeBoolean(boolean v) throws IOException {
    dataOutput.writeBoolean(v);
  }

  @Override
  public void writeByte(int v) throws IOException {
    dataOutput.writeByte(v);
  }

  @Override
  public void writeShort(int v) throws IOException {
    dataOutput.writeShort(v);
  }

  @Override
  public void writeChar(int v) throws IOException {
    dataOutput.writeChar(v);
  }

  @Override
  public void writeInt(int v) throws IOException {
    dataOutput.writeInt(v);
  }

  @Override
  public void writeLong(long v) throws IOException {
    dataOutput.writeLong(v);
  }

  @Override
  public void writeFloat(float v) throws IOException {
    dataOutput.writeFloat(v);
  }

  @Override
  public void writeDouble(double v) throws IOException {
    dataOutput.writeDouble(v);
  }

  @Override
  public void writeBytes(String s) throws IOException {
    dataOutput.writeBytes(s);
  }

  @Override
  public void writeChars(String s) throws IOException {
    dataOutput.writeChars(s);
  }

  @Override
  public void writeUTF(String s) throws IOException {
    dataOutput.writeUTF(s);
  }

  @Override
  public void ensureWritable(int minSize) {
    if ((count + minSize) > buf.length) {
      buf = Arrays.copyOf(buf, Math.max(buf.length << 1, count + minSize));
    }
  }

  @Override
  public void skipBytes(int bytesToSkip) {
    ensureWritable(bytesToSkip);
    count += bytesToSkip;
  }

  @Override
  public void writeInt(int position, int value) {
    if (position + 4 > count) {
      throw new IndexOutOfBoundsException(
          "writeIntOnPosition: Tried to write int to position " + position +
              " but current length is " + count);
    }
    buf[position] = (byte) ((value >>> 24) & 0xFF);
    buf[position + 1] = (byte) ((value >>> 16) & 0xFF);
    buf[position + 2] = (byte) ((value >>> 8) & 0xFF);
    buf[position + 3] = (byte) ((value >>> 0) & 0xFF);
  }

  @Override
  public byte[] toByteArray(int offset, int length) {
    if (offset + length > count) {
      throw new IndexOutOfBoundsException(String.format("Offset: %d + " +
          "Length: %d exceeds the size of buf : %d", offset, length, count));
    }
    return Arrays.copyOfRange(buf, offset, length);
  }

  @Override
  public byte[] getByteArray() {
    return buf;
  }

  @Override
  public int getPos() {
    return count;
  }
}