1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one or more
3    * contributor license agreements. See the NOTICE file distributed with this
4    * work for additional information regarding copyright ownership. The ASF
5    * licenses this file to you under the Apache License, Version 2.0 (the
6    * "License"); you may not use this file except in compliance with the License.
7    * You may obtain a copy of the License at
8    *
9    * http://www.apache.org/licenses/LICENSE-2.0
10   *
11   * Unless required by applicable law or agreed to in writing, software
12   * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
13   * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
14   * License for the specific language governing permissions and limitations
15   * under the License.
16   */
17  package org.apache.hadoop.hbase.util;
18  
19  import java.util.Random;
20  
21  import org.apache.hadoop.hbase.util.Bytes;
22  import org.apache.hadoop.hbase.util.MD5Hash;
23  
24  /**
25   * A generator of random keys and values for load testing. Keys are generated
26   * by converting numeric indexes to strings and prefixing them with an MD5
27   * hash. Values are generated by selecting value size in the configured range
28   * and generating a pseudo-random sequence of bytes seeded by key, column
29   * qualifier, and value size.
30   * <p>
31   * Not thread-safe, so a separate instance is needed for every writer thread/
32   */
33  public class LoadTestKVGenerator {
34  
35    /** A random number generator for determining value size */
36    private Random randomForValueSize = new Random();
37  
38    private final int minValueSize;
39    private final int maxValueSize;
40  
41    public LoadTestKVGenerator(int minValueSize, int maxValueSize) {
42      if (minValueSize <= 0 || maxValueSize <= 0) {
43        throw new IllegalArgumentException("Invalid min/max value sizes: " +
44            minValueSize + ", " + maxValueSize);
45      }
46      this.minValueSize = minValueSize;
47      this.maxValueSize = maxValueSize;
48    }
49  
50    /**
51     * Verifies that the given byte array is the same as what would be generated
52     * for the given row key and qualifier. We are assuming that the value size
53     * is correct, and only verify the actual bytes. However, if the min/max
54     * value sizes are set sufficiently high, an accidental match should be
55     * extremely improbable.
56     */
57    public static boolean verify(String rowKey, String qual, byte[] value) {
58      byte[] expectedData = getValueForRowColumn(rowKey, qual, value.length);
59      return Bytes.equals(expectedData, value);
60    }
61  
62    /**
63     * Converts the given key to string, and prefixes it with the MD5 hash of
64     * the index's string representation.
65     */
66    public static String md5PrefixedKey(long key) {
67      String stringKey = Long.toString(key);
68      String md5hash = MD5Hash.getMD5AsHex(Bytes.toBytes(stringKey));
69  
70      // flip the key to randomize
71      return md5hash + "-" + stringKey;
72    }
73  
74    /**
75     * Generates a value for the given key index and column qualifier. Size is
76     * selected randomly in the configured range. The generated value depends
77     * only on the combination of the key, qualifier, and the selected value
78     * size. This allows to verify the actual value bytes when reading, as done
79     * in {@link #verify(String, String, byte[])}.
80     */
81    public byte[] generateRandomSizeValue(long key, String qual) {
82      String rowKey = md5PrefixedKey(key);
83      int dataSize = minValueSize + randomForValueSize.nextInt(
84          Math.abs(maxValueSize - minValueSize));
85      return getValueForRowColumn(rowKey, qual, dataSize);
86    }
87  
88    /**
89     * Generates random bytes of the given size for the given row and column
90     * qualifier. The random seed is fully determined by these parameters.
91     */
92    private static byte[] getValueForRowColumn(String rowKey, String qual,
93        int dataSize) {
94      Random seededRandom = new Random(rowKey.hashCode() + qual.hashCode() +
95          dataSize);
96      byte[] randomBytes = new byte[dataSize];
97      seededRandom.nextBytes(randomBytes);
98      return randomBytes;
99    }
100 
101 }