/** repeated weakCompareAndSet succeeds in changing value when equal to expected */
public void testWeakCompareAndSet() {
AtomicReferenceFieldUpdater<AtomicReferenceFieldUpdaterTest, Integer> a;
try {
a =
AtomicReferenceFieldUpdater.newUpdater(
AtomicReferenceFieldUpdaterTest.class, Integer.class, "x");
} catch (RuntimeException ok) {
return;
}
x = one;
while (!a.weakCompareAndSet(this, one, two)) ;
while (!a.weakCompareAndSet(this, two, m4)) ;
assertSame(m4, a.get(this));
while (!a.weakCompareAndSet(this, m4, seven)) ;
assertSame(seven, a.get(this));
}
/** get returns the last value lazySet by same thread */
public void testGetLazySet() {
AtomicReferenceFieldUpdater<AtomicReferenceFieldUpdaterTest, Integer> a;
try {
a =
AtomicReferenceFieldUpdater.newUpdater(
AtomicReferenceFieldUpdaterTest.class, Integer.class, "x");
} catch (RuntimeException ok) {
return;
}
x = one;
assertSame(one, a.get(this));
a.lazySet(this, two);
assertSame(two, a.get(this));
a.lazySet(this, m3);
assertSame(m3, a.get(this));
}
/** compareAndSet in one thread enables another waiting for value to succeed */
public void testCompareAndSetInMultipleThreads() throws Exception {
x = one;
final AtomicReferenceFieldUpdater<AtomicReferenceFieldUpdaterTest, Integer> a;
try {
a =
AtomicReferenceFieldUpdater.newUpdater(
AtomicReferenceFieldUpdaterTest.class, Integer.class, "x");
} catch (RuntimeException ok) {
return;
}
Thread t =
new Thread(
new CheckedRunnable() {
public void realRun() {
while (!a.compareAndSet(AtomicReferenceFieldUpdaterTest.this, two, three))
Thread.yield();
}
});
t.start();
assertTrue(a.compareAndSet(this, one, two));
t.join(LONG_DELAY_MS);
assertFalse(t.isAlive());
assertSame(a.get(this), three);
}