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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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import java.util.Objects;
import sun.misc.VM;
/**
* @test
* @bug 8068730
* @summary tests that VM.getgetNanoTimeAdjustment() works as expected.
* @modules java.base/sun.misc
* @run main GetNanoTimeAdjustment
* @author danielfuchs
*/
public class GetNanoTimeAdjustment {
static final int MILLIS_IN_SECOND = 1000;
static final int NANOS_IN_MILLI = 1000_000;
static final int NANOS_IN_MICRO = 1000;
static final int NANOS_IN_SECOND = 1000_000_000;
static final boolean verbose = true;
static final class TestAssertException extends RuntimeException {
TestAssertException(String msg) { super(msg); }
}
private static void assertEquals(long expected, long received, String msg) {
if (expected != received) {
throw new TestAssertException("Unexpected result for " + msg
+ ".\n\texpected: " + expected
+ "\n\tactual: " + received);
} else if (verbose) {
System.out.println("Got expected " + msg + ": " + received);
}
}
private static void assertEquals(Object expected, Object received, String msg) {
if (!Objects.equals(expected, received)) {
throw new TestAssertException("Unexpected result for " + msg
+ ".\n\texpected: " + expected
+ "\n\tactual: " + received);
} else if (verbose) {
System.out.println("Got expected " + msg + ": " + received);
}
}
static final long MAX_OFFSET = 0x0100000000L;
static final long MIN_OFFSET = -MAX_OFFSET;
static enum Answer {
YES, // isOffLimit = YES: we must get -1
NO, // isOffLimit = NO: we must not not get -1
MAYBE // isOffLimit = MAYBE: we might get -1 or a valid adjustment.
};
static long distance(long one, long two) {
return one > two ? Math.subtractExact(one, two)
: Math.subtractExact(two, one);
}
static Answer isOffLimits(long before, long after, long offset) {
long relativeDistanceBefore = distance(before, offset);
long relativeDistanceAfter = distance(after, offset);
if (relativeDistanceBefore >= MAX_OFFSET && relativeDistanceAfter >= MAX_OFFSET) {
return Answer.YES;
}
if (relativeDistanceBefore < MAX_OFFSET && relativeDistanceAfter < MAX_OFFSET) {
if (relativeDistanceBefore == 0 || relativeDistanceAfter == 0) {
return Answer.MAYBE; // unlucky case where
}
return Answer.NO;
}
return Answer.MAYBE;
}
static void testWithOffset(String name, long offset) {
System.out.println("Testing with offset: " + name);
long beforeMillis = System.currentTimeMillis();
long adjustment = VM.getNanoTimeAdjustment(offset);
long afterMillis = System.currentTimeMillis();
if (offset >= beforeMillis/MILLIS_IN_SECOND
&& offset <= afterMillis/MILLIS_IN_SECOND) {
if (adjustment == -1) {
// it's possible that we have fallen in the unlucky case
// where -1 was the genuine result. let's go backward a bit.
offset = offset - 10;
beforeMillis = System.currentTimeMillis();
adjustment = VM.getNanoTimeAdjustment(offset);
afterMillis = System.currentTimeMillis();
if (adjustment == -1) {
throw new RuntimeException(name + ": VM says " + offset
+ " secs is too far off, "
+ " when time in seconds is in ["
+ beforeMillis/MILLIS_IN_SECOND + ", "
+ afterMillis/MILLIS_IN_SECOND
+ "]");
}
}
}
Answer isOffLimit = isOffLimits(beforeMillis/MILLIS_IN_SECOND,
afterMillis/MILLIS_IN_SECOND, offset);
switch (isOffLimit) {
case YES:
if (adjustment != -1) {
throw new RuntimeException(name
+ ": VM should have returned -1 for "
+ offset
+ " when time in seconds is in ["
+ beforeMillis/MILLIS_IN_SECOND + ", "
+ afterMillis/MILLIS_IN_SECOND + "]");
}
System.out.println("Got expected exception value: " + adjustment);
break;
case NO:
if (adjustment == -1) {
throw new RuntimeException(name
+ "VM says " + offset
+ " secs is too far off, "
+ " when time in seconds is in ["
+ beforeMillis/MILLIS_IN_SECOND + ", "
+ afterMillis/MILLIS_IN_SECOND
+ "]");
}
break;
case MAYBE:
System.out.println("Adjustment: " + adjustment);
System.out.println("Can't assert for -1 with offset "
+ offset + "(" + name + ")"
+ " when time in seconds is in ["
+ beforeMillis/MILLIS_IN_SECOND + ", "
+ afterMillis/MILLIS_IN_SECOND
+ "]");
// not conclusive
}
if (isOffLimit == Answer.NO || adjustment != -1) {
System.out.println("Validating adjustment: " + adjustment);
long expectedMax = distance(offset, beforeMillis/MILLIS_IN_SECOND)
* NANOS_IN_SECOND
+ (beforeMillis % MILLIS_IN_SECOND) * NANOS_IN_MILLI
+ (afterMillis - beforeMillis + 1) * NANOS_IN_MILLI;
long absoluteAdjustment = distance(0, adjustment);
if (absoluteAdjustment > expectedMax) {
long adjSec = absoluteAdjustment / NANOS_IN_SECOND;
long adjMil = (absoluteAdjustment % NANOS_IN_SECOND) / NANOS_IN_MILLI;
long adjMic = (absoluteAdjustment % NANOS_IN_MILLI) / NANOS_IN_MICRO;
long adjNan = (absoluteAdjustment % NANOS_IN_MICRO);
long expSec = expectedMax / NANOS_IN_SECOND;
long expMil = (expectedMax % NANOS_IN_SECOND) / NANOS_IN_MILLI;
long expMic = (expectedMax % NANOS_IN_MILLI) / NANOS_IN_MICRO;
long expNan = (expectedMax % NANOS_IN_MICRO);
System.err.println("Excessive adjustment: " + adjSec + "s, "
+ adjMil + "ms, " + adjMic + "mics, " + adjNan + "ns");
System.err.println("Epected max: " + expSec + "s, "
+ expMil + "ms, " + expMic + "mics, " + expNan + "ns");
throw new RuntimeException(name
+ ": Excessive adjustment: " + adjustment
+ " when time in millis is in ["
+ beforeMillis + ", " + afterMillis
+ "] and offset in seconds is " + offset);
}
}
}
static void regular() {
System.out.println("*** Testing regular cases ***");
final long start = System.currentTimeMillis();
long offset = start/1000;
long adjustment = VM.getNanoTimeAdjustment(offset);
if (start != offset*1000) {
if (adjustment == -1) {
throw new RuntimeException("VM says " + offset
+ " secs is too far off, but time millis is "
+ System.currentTimeMillis());
}
}
if (adjustment == -1) {
offset = System.currentTimeMillis()/1000 - 1024;
adjustment = VM.getNanoTimeAdjustment(offset);
if (adjustment == -1) {
throw new RuntimeException("VM says " + offset
+ " secs is too far off, but time millis is "
+ System.currentTimeMillis());
}
}
if (adjustment > (start/1000 - offset + 20)*NANOS_IN_SECOND) {
throw new RuntimeException("Excessive adjustment: " + adjustment);
}
testWithOffset("System.currentTimeMillis()/1000",
System.currentTimeMillis()/1000);
testWithOffset("System.currentTimeMillis()/1000 - 1024",
System.currentTimeMillis()/1000 - 1024);
testWithOffset("System.currentTimeMillis()/1000 + 1024",
System.currentTimeMillis()/1000 + 1024);
}
static void testLimits() {
System.out.println("*** Testing limits ***");
testWithOffset("System.currentTimeMillis()/1000 - MAX_OFFSET + 1",
System.currentTimeMillis()/1000 - MAX_OFFSET + 1);
testWithOffset("System.currentTimeMillis()/1000 + MAX_OFFSET - 1",
System.currentTimeMillis()/1000 + MAX_OFFSET - 1);
testWithOffset("System.currentTimeMillis()/1000 - MAX_OFFSET",
System.currentTimeMillis()/1000 - MAX_OFFSET);
testWithOffset("System.currentTimeMillis()/1000 + MAX_OFFSET",
System.currentTimeMillis()/1000 + MAX_OFFSET);
testWithOffset("System.currentTimeMillis()/1000 - MAX_OFFSET - 1024",
System.currentTimeMillis()/1000 - MAX_OFFSET - 1024);
testWithOffset("System.currentTimeMillis()/1000 + MAX_OFFSET + 1024",
System.currentTimeMillis()/1000 + MAX_OFFSET + 1024);
testWithOffset("0", 0);
testWithOffset("-1", -1);
testWithOffset("Integer.MAX_VALUE + System.currentTimeMillis()/1000",
((long)Integer.MAX_VALUE) + System.currentTimeMillis()/1000);
testWithOffset("System.currentTimeMillis()/1000 - Integer.MIN_VALUE",
System.currentTimeMillis()/1000 - Integer.MIN_VALUE);
testWithOffset("Long.MAX_VALUE", Long.MAX_VALUE);
testWithOffset("System.currentTimeMillis()/1000 - Long.MIN_VALUE",
(Long.MIN_VALUE + System.currentTimeMillis()/1000)*-1);
}
public static void main(String[] args) throws Exception {
regular();
testLimits();
}
}