@Test
public void testProcessMatchingLock() throws Exception {
ExpiryMarker original =
new ExpiryMarker(null, 100L, "the-marker-id").markForExpiration(100L, "some-marker-id");
Map.Entry<Object, Expirable> entry = mockEntry(original);
UnlockEntryProcessor processor =
new UnlockEntryProcessor(
new ExpiryMarker(null, 100L, "the-marker-id"), "next-marker-id", 150L);
ArgumentCaptor<Expirable> captor = ArgumentCaptor.forClass(Expirable.class);
processor.process(entry);
verify(entry).setValue(captor.capture());
Expirable result = captor.getValue();
assertNotSame(original, result);
assertThat(result, instanceOf(ExpiryMarker.class));
ExpiryMarker marker = (ExpiryMarker) result;
assertTrue(marker.matches(original));
}
@Test
public void testProcessWithValue() throws Exception {
Map.Entry<Object, Expirable> entry = mockEntry(new Value(null, 100L, "some-value"));
UnlockEntryProcessor processor =
new UnlockEntryProcessor(
new ExpiryMarker(null, 100L, "other-marker-id"), "next-marker-id", 150L);
ArgumentCaptor<Expirable> captor = ArgumentCaptor.forClass(Expirable.class);
processor.process(entry);
verify(entry).setValue(captor.capture());
Expirable result = captor.getValue();
assertThat(result, instanceOf(ExpiryMarker.class));
ExpiryMarker marker = (ExpiryMarker) result;
assertFalse(
"market must be expirable after timestamp", marker.isReplaceableBy(150L, null, null));
assertTrue(
"market must be expirable after timestamp", marker.isReplaceableBy(151L, null, null));
}
@Override
public Boolean process(Map.Entry<Object, Expirable> entry) {
Expirable expirable = entry.getValue();
boolean updated;
if (expirable == null) {
// Nothing there. The entry was evicted? It should be safe to replace it
expirable = new Value(newVersion, timestamp, newValue);
updated = true;
} else {
if (expirable.matches(lock)) {
final ExpiryMarker marker = (ExpiryMarker) expirable;
if (marker.isConcurrent()) {
// Multiple transactions are attempting to update the same entry. Its highly
// likely that the value we are attempting to set is invalid. Instead just
// expire the entry and allow the next put to the cache to succeed if no more
// transactions are in-flight.
expirable = marker.expire(timestamp);
updated = false;
} else {
// Only one transaction attempted to update the entry so it is safe to replace
// it with the value supplied
expirable = new Value(newVersion, timestamp, newValue);
updated = true;
}
} else if (expirable.getValue() == null) {
// It's a different marker, Leave it as is
return false;
} else {
// It's a value. We have no way to see which is correct so we expire the entry.
// It is expired instead of removed to prevent in progress transactions from
// putting stale values into the cache
expirable = new ExpiryMarker(newVersion, timestamp, nextMarkerId).expire(timestamp);
updated = false;
}
}
entry.setValue(expirable);
return updated;
}