001/**
002 *
003 * Licensed to the Apache Software Foundation (ASF) under one
004 * or more contributor license agreements.  See the NOTICE file
005 * distributed with this work for additional information
006 * regarding copyright ownership.  The ASF licenses this file
007 * to you under the Apache License, Version 2.0 (the
008 * "License"); you may not use this file except in compliance
009 * with the License.  You may obtain a copy of the License at
010 *
011 *     http://www.apache.org/licenses/LICENSE-2.0
012 *
013 * Unless required by applicable law or agreed to in writing, software
014 * distributed under the License is distributed on an "AS IS" BASIS,
015 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
016 * See the License for the specific language governing permissions and
017 * limitations under the License.
018 */
019package org.apache.hadoop.hbase.filter;
020
021import java.nio.ByteBuffer;
022
023import org.apache.hadoop.hbase.exceptions.DeserializationException;
024import org.apache.hadoop.hbase.util.ByteBufferUtils;
025import org.apache.hadoop.hbase.util.Bytes;
026import org.apache.yetus.audience.InterfaceAudience;
027
028
029/** Base class for byte array comparators */
030@InterfaceAudience.Public
031// TODO Now we are deviating a lot from the actual Comparable<byte[]> that this implements, by
032// adding special compareTo methods. We have to clean it. Deprecate this class and replace it
033// with a more generic one which says it compares bytes (not necessary a byte array only)
034// BytesComparable implements Comparable<Byte> will work?
035@SuppressWarnings("ComparableType") // Should this move to Comparator usage?
036public abstract class ByteArrayComparable implements Comparable<byte[]> {
037
038  byte[] value;
039
040  /**
041   * Constructor.
042   * @param value the value to compare against
043   */
044  public ByteArrayComparable(byte [] value) {
045    this.value = value;
046  }
047
048  public byte[] getValue() {
049    return value;
050  }
051
052  /**
053   * @return The comparator serialized using pb
054   */
055  public abstract byte [] toByteArray();
056
057  /**
058   * @param pbBytes A pb serialized {@link ByteArrayComparable} instance
059   * @return An instance of {@link ByteArrayComparable} made from <code>bytes</code>
060   * @throws DeserializationException
061   * @see #toByteArray
062   */
063  public static ByteArrayComparable parseFrom(final byte [] pbBytes)
064  throws DeserializationException {
065    throw new DeserializationException(
066      "parseFrom called on base ByteArrayComparable, but should be called on derived type");
067  }
068
069  /**
070   * @param other
071   * @return true if and only if the fields of the comparator that are serialized
072   * are equal to the corresponding fields in other.  Used for testing.
073   */
074  boolean areSerializedFieldsEqual(ByteArrayComparable other) {
075    if (other == this) return true;
076
077    return Bytes.equals(this.getValue(), other.getValue());
078  }
079
080  @Override
081  public int compareTo(byte [] value) {
082    return compareTo(value, 0, value.length);
083  }
084
085  /**
086   * Special compareTo method for subclasses, to avoid
087   * copying byte[] unnecessarily.
088   * @param value byte[] to compare
089   * @param offset offset into value
090   * @param length number of bytes to compare
091   * @return a negative integer, zero, or a positive integer as this object
092   *         is less than, equal to, or greater than the specified object.
093   */
094  public abstract int compareTo(byte [] value, int offset, int length);
095
096  /**
097   * Special compareTo method for subclasses, to avoid copying bytes unnecessarily.
098   * @param value bytes to compare within a ByteBuffer
099   * @param offset offset into value
100   * @param length number of bytes to compare
101   * @return a negative integer, zero, or a positive integer as this object
102   *         is less than, equal to, or greater than the specified object.
103   */
104  public int compareTo(ByteBuffer value, int offset, int length) {
105    // For BC, providing a default implementation here which is doing a bytes copy to a temp byte[]
106    // and calling compareTo(byte[]). Make sure to override this method in subclasses to avoid
107    // copying bytes unnecessarily.
108    byte[] temp = new byte[length];
109    ByteBufferUtils.copyFromBufferToArray(temp, value, offset, 0, length);
110    return compareTo(temp);
111  }
112}