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.test;
18
19 import java.util.Random;
20
21 import org.apache.commons.logging.Log;
22 import org.apache.commons.logging.LogFactory;
23 import org.apache.hadoop.hbase.classification.InterfaceAudience;
24 import org.apache.hadoop.hbase.util.Bytes;
25 import org.apache.hadoop.hbase.util.MD5Hash;
26
27 /**
28 * A generator of random keys and values for load testing. Keys are generated
29 * by converting numeric indexes to strings and prefixing them with an MD5
30 * hash. Values are generated by selecting value size in the configured range
31 * and generating a pseudo-random sequence of bytes seeded by key, column
32 * qualifier, and value size.
33 */
34 @InterfaceAudience.Private
35 public class LoadTestKVGenerator {
36
37 private static final Log LOG = LogFactory.getLog(LoadTestKVGenerator.class);
38 private static int logLimit = 10;
39
40 /** A random number generator for determining value size */
41 private Random randomForValueSize = new Random();
42
43 private final int minValueSize;
44 private final int maxValueSize;
45
46 public LoadTestKVGenerator(int minValueSize, int maxValueSize) {
47 if (minValueSize <= 0 || maxValueSize <= 0) {
48 throw new IllegalArgumentException("Invalid min/max value sizes: " +
49 minValueSize + ", " + maxValueSize);
50 }
51 this.minValueSize = minValueSize;
52 this.maxValueSize = maxValueSize;
53 }
54
55 /**
56 * Verifies that the given byte array is the same as what would be generated
57 * for the given seed strings (row/cf/column/...). We are assuming that the
58 * value size is correct, and only verify the actual bytes. However, if the
59 * min/max value sizes are set sufficiently high, an accidental match should be
60 * extremely improbable.
61 */
62 public static boolean verify(byte[] value, byte[]... seedStrings) {
63 byte[] expectedData = getValueForRowColumn(value.length, seedStrings);
64 boolean equals = Bytes.equals(expectedData, value);
65 if (!equals && LOG.isDebugEnabled() && logLimit > 0) {
66 LOG.debug("verify failed, expected value: " + Bytes.toStringBinary(expectedData)
67 + " actual value: "+ Bytes.toStringBinary(value));
68 logLimit--; // this is not thread safe, but at worst we will have more logging
69 }
70 return equals;
71 }
72
73 /**
74 * Converts the given key to string, and prefixes it with the MD5 hash of
75 * the index's string representation.
76 */
77 public static String md5PrefixedKey(long key) {
78 String stringKey = Long.toString(key);
79 String md5hash = MD5Hash.getMD5AsHex(Bytes.toBytes(stringKey));
80
81 // flip the key to randomize
82 return md5hash + "-" + stringKey;
83 }
84
85 /**
86 * Generates a value for the given key index and column qualifier. Size is
87 * selected randomly in the configured range. The generated value depends
88 * only on the combination of the strings passed (key/cf/column/...) and the selected
89 * value size. This allows to verify the actual value bytes when reading, as done
90 * in {#verify(byte[], byte[]...)}
91 * This method is as thread-safe as Random class. It appears that the worst bug ever
92 * found with the latter is that multiple threads will get some duplicate values, which
93 * we don't care about.
94 */
95 public byte[] generateRandomSizeValue(byte[]... seedStrings) {
96 int dataSize = minValueSize;
97 if(minValueSize != maxValueSize) {
98 dataSize = minValueSize + randomForValueSize.nextInt(Math.abs(maxValueSize - minValueSize));
99 }
100 return getValueForRowColumn(dataSize, seedStrings);
101 }
102
103 /**
104 * Generates random bytes of the given size for the given row and column
105 * qualifier. The random seed is fully determined by these parameters.
106 */
107 private static byte[] getValueForRowColumn(int dataSize, byte[]... seedStrings) {
108 long seed = dataSize;
109 for (byte[] str : seedStrings) {
110 seed += Bytes.toString(str).hashCode();
111 }
112 Random seededRandom = new Random(seed);
113 byte[] randomBytes = new byte[dataSize];
114 seededRandom.nextBytes(randomBytes);
115 return randomBytes;
116 }
117
118 }