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/*

 * @test

 * @bug     4858522

 * @summary Basic unit test of HotspotRuntimeMBean.getSafepointSyncTime()

 * @author  Steve Bohne

 *

 * @run main/othervm -XX:+UsePerfData GetSafepointSyncTime

 */

/*

 * This test is just a sanity check and does not check for the correct value.

 */

import sun.management.*;

public class GetSafepointSyncTime {

    private static HotspotRuntimeMBean mbean =

        (HotspotRuntimeMBean)ManagementFactoryHelper.getHotspotRuntimeMBean();

    private static final long NUM_THREAD_DUMPS = 300;

    // Careful with these values.

    private static final long MIN_VALUE_FOR_PASS = 1;

    private static final long MAX_VALUE_FOR_PASS = Long.MAX_VALUE;

    public static void main(String args[]) throws Exception {

        long count = mbean.getSafepointCount();

        long value = mbean.getSafepointSyncTime();

        // Thread.getAllStackTraces() should cause safepoints.

        // If this test is failing because it doesn't,

        // MIN_VALUE_FOR_PASS should be reset to 0

        for (int i = 0; i < NUM_THREAD_DUMPS; i++) {

            Thread.getAllStackTraces();

        }

        long count1 = mbean.getSafepointCount();

        long value1 = mbean.getSafepointSyncTime();

        System.out.format("Safepoint count=%d (diff=%d), sync time=%d ms (diff=%d)%n",

                          count1, count1-count, value1, value1-value);

        if (value1 < MIN_VALUE_FOR_PASS || value1 > MAX_VALUE_FOR_PASS) {

            throw new RuntimeException("Safepoint sync time " +

                                       "illegal value: " + value1 + " ms " +

                                       "(MIN = " + MIN_VALUE_FOR_PASS + "; " +

                                       "MAX = " + MAX_VALUE_FOR_PASS + ")");

        }

        for (int i = 0; i < NUM_THREAD_DUMPS; i++) {

            Thread.getAllStackTraces();

        }

        long count2 = mbean.getSafepointCount();

        long value2 = mbean.getSafepointSyncTime();

        System.out.format("Safepoint count=%d (diff=%d), sync time=%d ms (diff=%d)%n",

                          count2, count2-count1, value2, value2-value1);

        if (value2 <= value1) {

            throw new RuntimeException("Safepoint sync time " +

                                       "did not increase " +

                                       "(value1 = " + value1 + "; " +

                                       "value2 = " + value2 + ")");

        }

        System.out.println("Test passed.");

    }

}