static TreeSet<UUID> add(TreeSet<UUID> a, UUID uuid, boolean reversed, int limit) {
if (a == null) {
a = new TreeSet<UUID>(new UUIDComparator());
}
if (uuid == null) {
return a;
}
// if we have less than the limit, just add it
if (a.size() < limit) {
a.add(uuid);
} else if (reversed) {
// if reversed, we want to add more recent messages
// and eject the oldest
if (UUIDComparator.staticCompare(uuid, a.first()) > 0) {
a.pollFirst();
a.add(uuid);
}
} else {
// add older messages and eject the newset
if (UUIDComparator.staticCompare(uuid, a.last()) < 0) {
a.pollLast();
a.add(uuid);
}
}
return a;
}
@Test
public void getReversedEntries() throws ConnectionException {
final Id applicationId = new SimpleId("application");
ApplicationScope context = new ApplicationScopeImpl(applicationId);
final Id id = new SimpleId("test");
int count = 10;
final UUID[] versions = new UUID[count];
final Stage COMPLETE = Stage.COMPLETE;
final MvccLogEntry[] entries = new MvccLogEntry[count];
for (int i = 0; i < count; i++) {
versions[i] = UUIDGenerator.newTimeUUID();
entries[i] = new MvccLogEntryImpl(id, versions[i], COMPLETE, MvccLogEntry.State.COMPLETE);
logEntryStrategy.write(context, entries[i]).execute();
// Read it back
MvccLogEntry returned =
logEntryStrategy.load(context, Collections.singleton(id), versions[i]).getMaxVersion(id);
assertNotNull("Returned value should not be null", returned);
assertEquals("Returned should equal the saved", entries[i], returned);
}
final UUID[] assertVersions = Arrays.copyOf(versions, versions.length);
Arrays.sort(assertVersions, (v1, v2) -> UUIDComparator.staticCompare(v1, v2) * -1);
// now do a range scan from the end
final int half = count / 2;
final List<MvccLogEntry> results =
logEntryStrategy.loadReversed(context, id, versions[0], half);
assertEquals(half, results.size());
for (int i = 0; i < count / 2; i++) {
final MvccLogEntry saved = entries[i];
final MvccLogEntry returned = results.get(i);
assertEquals("Entry was not equal to the saved value", saved, returned);
}
// now get the next batch
final List<MvccLogEntry> results2 =
logEntryStrategy.loadReversed(context, id, versions[half], count);
assertEquals(half, results2.size());
for (int i = 0; i < half; i++) {
final MvccLogEntry saved = entries[half + i];
final MvccLogEntry returned = results2.get(i);
assertEquals("Entry was not equal to the saved value", saved, returned);
}
// now delete them all and ensure we get no results back
for (int i = 0; i < count; i++) {
logEntryStrategy.delete(context, id, versions[i]).execute();
}
final List<MvccLogEntry> results3 =
logEntryStrategy.loadReversed(context, id, null, versions.length);
assertEquals("All log entries were deleted", 0, results3.size());
}