123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778 |
- /*
- * Copyright (C) 2009, Christian Halstrick <christian.halstrick@sap.com> and others
- *
- * This program and the accompanying materials are made available under the
- * terms of the Eclipse Distribution License v. 1.0 which is available at
- * https://www.eclipse.org/org/documents/edl-v10.php.
- *
- * SPDX-License-Identifier: BSD-3-Clause
- */
-
- package org.eclipse.jgit.util;
-
- import java.lang.management.ManagementFactory;
- import java.lang.management.ThreadMXBean;
-
- /**
- * A simple stopwatch which measures elapsed CPU time of the current thread. CPU
- * time is the time spent on executing your own code plus the time spent on
- * executing operating system calls triggered by your application.
- * <p>
- * This stopwatch needs a VM which supports getting CPU Time information for the
- * current thread. The static method createInstance() will take care to return
- * only a new instance of this class if the VM is capable of returning CPU time.
- */
- public class CPUTimeStopWatch {
- private long start;
-
- private static ThreadMXBean mxBean=ManagementFactory.getThreadMXBean();
-
- /**
- * use this method instead of the constructor to be sure that the underlying
- * VM provides all features needed by this class.
- *
- * @return a new instance of {@link #CPUTimeStopWatch()} or
- * <code>null</code> if the VM does not support getting CPU time
- * information
- */
- public static CPUTimeStopWatch createInstance() {
- return mxBean.isCurrentThreadCpuTimeSupported() ? new CPUTimeStopWatch()
- : null;
- }
-
- /**
- * Starts the stopwatch. If the stopwatch is already started this will
- * restart the stopwatch.
- */
- public void start() {
- start = mxBean.getCurrentThreadCpuTime();
- }
-
- /**
- * Stops the stopwatch and return the elapsed CPU time in nanoseconds.
- * Should be called only on started stopwatches.
- *
- * @return the elapsed CPU time in nanoseconds. When called on non-started
- * stopwatches (either because {@link #start()} was never called or
- * {@link #stop()} was called after the last call to
- * {@link #start()}) this method will return 0.
- */
- public long stop() {
- long cpuTime = readout();
- start = 0;
- return cpuTime;
- }
-
- /**
- * Return the elapsed CPU time in nanoseconds. In contrast to
- * {@link #stop()} the stopwatch will continue to run after this call.
- *
- * @return the elapsed CPU time in nanoseconds. When called on non-started
- * stopwatches (either because {@link #start()} was never called or
- * {@link #stop()} was called after the last call to
- * {@link #start()}) this method will return 0.
- */
- public long readout() {
- return (start == 0) ? 0 : mxBean.getCurrentThreadCpuTime() - start;
- }
- }
|