1847 

  1848 int os::sleep(JavaThread* thread, jlong millis) {

  1849   assert(thread == Thread::current(),  "thread consistency check");

  1850 

  1851   ParkEvent * const slp = thread->_SleepEvent;

  1852   // Because there can be races with thread interruption sending an unpark()

  1853   // to the event, we explicitly reset it here to avoid an immediate return.

  1854   // The actual interrupt state will be checked before we park().

  1855   slp->reset();

  1856   // Thread interruption establishes a happens-before ordering in the

  1857   // Java Memory Model, so we need to ensure we synchronize with the

  1858   // interrupt state.

  1859   OrderAccess::fence();

  1860 

  1861   jlong prevtime = javaTimeNanos();

  1862 

  1863   for (;;) {

  1864     // interruption has precedence over timing out

  1865     if (os::is_interrupted(thread, true)) {

  1866       return OS_INTRPT;

  1867     }

  1868 

  1869     jlong newtime = javaTimeNanos();

  1870 

  1871     if (newtime - prevtime < 0) {

  1872       // time moving backwards, should only happen if no monotonic clock

  1873       // not a guarantee() because JVM should not abort on kernel/glibc bugs

  1874       assert(!os::supports_monotonic_clock(),

  1875              "unexpected time moving backwards detected in os::sleep()");

  1876     } else {

  1877       millis -= (newtime - prevtime) / NANOSECS_PER_MILLISEC;

  1878     }

  1879 

  1880     if (millis <= 0) {

  1881       return OS_OK;

  1882     }

  1883 

  1884     prevtime = newtime;

  1885 

  1886     {

  1887       ThreadBlockInVM tbivm(thread);

  1888       OSThreadWaitState osts(thread->osthread(), false /* not Object.wait() */);

  1889 

  1890       thread->set_suspend_equivalent();

  1891       // cleared by handle_special_suspend_equivalent_condition() or

  1892       // java_suspend_self() via check_and_wait_while_suspended()

  1893 

  1894       slp->park(millis);

  1895 

  1896       // were we externally suspended while we were waiting?

  1897       thread->check_and_wait_while_suspended();

  1898     }

  1899   }

  1900 }