1 /*******************************************************************************
2  * Copyright (c) 2000, 2006 IBM Corporation and others.
3  *
4  * This program and the accompanying materials
5  * are made available under the terms of the Eclipse Public License 2.0
6  * which accompanies this distribution, and is available at
7  * https://www.eclipse.org/legal/epl-2.0/
8  *
9  * SPDX-License-Identifier: EPL-2.0
10  *
11  * Contributors:
12  *     IBM Corporation - initial API and implementation
13  *******************************************************************************/
14 package org.eclipse.team.tests.ccvs.ui.benchmark;
15 
16 
17 import java.util.Random;
18 
19 /**
20  * Encapsulates algorithms and state for generating deterministic sequences.
21  * The sequence of numbers generated will always follow the same pattern,
22  * regardless of the time, place, or platform.
23  */
24 public class SequenceGenerator {
25 	private static long globalSeqNum = System.currentTimeMillis() * 1000;
26 	private final Random random;
27 	private int uniqueInt;
28 
29 	/**
30 	 * Constructs a new sequence generator with a known seed.
31 	 */
SequenceGenerator()32 	public SequenceGenerator() {
33 		random = new Random(3141592653589793238L); // a known constant
34 		uniqueInt = 1000000;
35 	}
36 
37 	/**
38 	 * Returns a globally unique long integer.
39 	 */
nextGloballyUniqueLong()40 	public static long nextGloballyUniqueLong() {
41 		return globalSeqNum++;
42 	}
43 
44 	/**
45 	 * Returns a unique 7-digit integer.
46 	 */
nextUniqueInt()47 	public int nextUniqueInt() {
48 		return uniqueInt++;
49 	}
50 
51 	/**
52 	 * Returns a pseudo-random integer between 0 and n-1.
53 	 * @see Random#nextInt(int)
54 	 */
nextInt(int n)55 	public int nextInt(int n) {
56 		return random.nextInt(n);
57 	}
58 
59 	/**
60 	 * Returns a pseudo-random real number following a gaussian distribution.
61 	 * @see Random#nextGaussian()
62 	 */
nextGaussian()63 	public double nextGaussian() {
64 		return random.nextGaussian();
65 	}
66 }
67