boolean casNext(Node cmp, Node val) {
boolean success = nextUpdater.compareAndSet(this, cmp, val);
if (!success) {
System.err.println("setting next failed");
}
return success;
}
/** 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);
}
/** compareAndSet succeeds in changing value if equal to expected else fails */
public void testCompareAndSet() {
AtomicReferenceFieldUpdater<AtomicReferenceFieldUpdaterTest, Integer> a;
try {
a =
AtomicReferenceFieldUpdater.newUpdater(
AtomicReferenceFieldUpdaterTest.class, Integer.class, "x");
} catch (RuntimeException ok) {
return;
}
x = one;
assertTrue(a.compareAndSet(this, one, two));
assertTrue(a.compareAndSet(this, two, m4));
assertSame(m4, a.get(this));
assertFalse(a.compareAndSet(this, m5, seven));
assertFalse(seven == a.get(this));
assertTrue(a.compareAndSet(this, m4, seven));
assertSame(seven, a.get(this));
}