001/*
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *     http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018package org.apache.hadoop.hbase.filter;
019
020import java.nio.ByteBuffer;
021import org.apache.hadoop.hbase.exceptions.DeserializationException;
022import org.apache.hadoop.hbase.util.ByteBufferUtils;
023import org.apache.hadoop.hbase.util.Bytes;
024import org.apache.yetus.audience.InterfaceAudience;
025
026/** Base class for byte array comparators */
027@InterfaceAudience.Public
028// TODO Now we are deviating a lot from the actual Comparable<byte[]> that this implements, by
029// adding special compareTo methods. We have to clean it. Deprecate this class and replace it
030// with a more generic one which says it compares bytes (not necessary a byte array only)
031// BytesComparable implements Comparable<Byte> will work?
032@SuppressWarnings("ComparableType") // Should this move to Comparator usage?
033public abstract class ByteArrayComparable implements Comparable<byte[]> {
034
035  byte[] value;
036
037  /**
038   * Constructor.
039   * @param value the value to compare against
040   */
041  public ByteArrayComparable(byte[] value) {
042    this.value = value;
043  }
044
045  public byte[] getValue() {
046    return value;
047  }
048
049  /** Returns The comparator serialized using pb */
050  public abstract byte[] toByteArray();
051
052  /**
053   * @param pbBytes A pb serialized {@link ByteArrayComparable} instance
054   * @return An instance of {@link ByteArrayComparable} made from <code>bytes</code>
055   * @see #toByteArray
056   */
057  public static ByteArrayComparable parseFrom(final byte[] pbBytes)
058    throws DeserializationException {
059    throw new DeserializationException(
060      "parseFrom called on base ByteArrayComparable, but should be called on derived type");
061  }
062
063  /**
064   * @return true if and only if the fields of the comparator that are serialized are equal to the
065   *         corresponding fields in other. Used for testing.
066   */
067  boolean areSerializedFieldsEqual(ByteArrayComparable other) {
068    if (other == this) return true;
069
070    return Bytes.equals(this.getValue(), other.getValue());
071  }
072
073  @Override
074  public int compareTo(byte[] value) {
075    return compareTo(value, 0, value.length);
076  }
077
078  /**
079   * Special compareTo method for subclasses, to avoid copying byte[] unnecessarily.
080   * @param value  byte[] to compare
081   * @param offset offset into value
082   * @param length number of bytes to compare
083   * @return a negative integer, zero, or a positive integer as this object is less than, equal to,
084   *         or greater than the specified object.
085   */
086  public abstract int compareTo(byte[] value, int offset, int length);
087
088  /**
089   * Special compareTo method for subclasses, to avoid copying bytes unnecessarily.
090   * @param value  bytes to compare within a ByteBuffer
091   * @param offset offset into value
092   * @param length number of bytes to compare
093   * @return a negative integer, zero, or a positive integer as this object is less than, equal to,
094   *         or greater than the specified object.
095   */
096  public int compareTo(ByteBuffer value, int offset, int length) {
097    // For BC, providing a default implementation here which is doing a bytes copy to a temp byte[]
098    // and calling compareTo(byte[]). Make sure to override this method in subclasses to avoid
099    // copying bytes unnecessarily.
100    byte[] temp = new byte[length];
101    ByteBufferUtils.copyFromBufferToArray(temp, value, offset, 0, length);
102    return compareTo(temp);
103  }
104}