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root/jsr166/jsr166/src/test/tck/StampedLockTest.java

Comparing jsr166/src/test/tck/StampedLockTest.java (file contents):
Revision 1.38 by jsr166, Thu Sep 21 17:52:52 2017 UTC vs.
Revision 1.39 by jsr166, Sun Sep 24 15:24:34 2017 UTC

#	Line 1226 | Line 1226 | public class StampedLockTest extends JSR
1226		for (Future<?> future : futures)
1227		assertNull(future.get());
1228		}
1229	+
1230	+	/** Tries out sample usage code from StampedLock javadoc. */
1231	+	public void testSampleUsage() throws Throwable {
1232	+	class Point {
1233	+	private double x, y;
1234	+	private final StampedLock sl = new StampedLock();
1235	+
1236	+	void move(double deltaX, double deltaY) { // an exclusively locked method
1237	+	long stamp = sl.writeLock();
1238	+	try {
1239	+	x += deltaX;
1240	+	y += deltaY;
1241	+	} finally {
1242	+	sl.unlockWrite(stamp);
1243	+	}
1244	+	}
1245	+
1246	+	double distanceFromOrigin() { // A read-only method
1247	+	double currentX, currentY;
1248	+	long stamp = sl.tryOptimisticRead();
1249	+	do {
1250	+	if (stamp == 0L)
1251	+	stamp = sl.readLock();
1252	+	try {
1253	+	// possibly racy reads
1254	+	currentX = x;
1255	+	currentY = y;
1256	+	} finally {
1257	+	stamp = sl.tryConvertToOptimisticRead(stamp);
1258	+	}
1259	+	} while (stamp == 0);
1260	+	return Math.hypot(currentX, currentY);
1261	+	}
1262	+	}
1263	+
1264	+	Point p = new Point();
1265	+	p.move(3.0, 4.0);
1266	+	assertEquals(5.0, p.distanceFromOrigin());
1267	+	}
1268	+
1269		}

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