TimeSource.java revision 12651:6ef01bd40ce2 
1/*
2 * Copyright (c) 2015, 2016, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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21 * questions.
22 */
23package org.graalvm.compiler.debug;
24
25import java.lang.management.ThreadMXBean;
26
27/**
28 * A consistent source of timing data that should be used by all facilities in the debug package.
29 */
30public class TimeSource {
31    private static final boolean USING_BEAN;
32    private static final ThreadMXBean threadMXBean;
33
34    static {
35        threadMXBean = Management.getThreadMXBean();
36        if (threadMXBean.isThreadCpuTimeSupported()) {
37            USING_BEAN = true;
38        } else {
39            USING_BEAN = false;
40        }
41    }
42
43    /**
44     * Gets the current time of this thread in nanoseconds from the most accurate timer available on
45     * the system. The returned value will be the current time in nanoseconds precision but not
46     * necessarily nanoseconds accuracy.
47     * <p>
48     * The intended use case of this method is to measure the time a certain action takes by making
49     * successive calls to it. It should not be used to measure total times in the sense of a time
50     * stamp.
51     *
52     * @return the current thread's time in nanoseconds
53     */
54    public static long getTimeNS() {
55        return USING_BEAN ? threadMXBean.getCurrentThreadCpuTime() : System.nanoTime();
56    }
57
58}
59