@Test
public void splitsEventsBackward() {
final String stream = generateStreamName();
List<EventData> events = newTestEvents(40);
eventstore.appendToStream(stream, ExpectedVersion.NO_STREAM, events).join();
Spliterator<ResolvedEvent> spliterator =
new StreamEventsSpliterator(
StreamPosition.END, i -> eventstore.readStreamEventsBackward(stream, i, 8, false));
List<ResolvedEvent> result = new ArrayList<>();
range(0, 5)
.forEach(
i -> {
Spliterator<ResolvedEvent> s = spliterator.trySplit();
assertNotNull(s);
s.forEachRemaining(result::add);
});
assertEquals(40, result.size());
assertNull(spliterator.trySplit());
spliterator.forEachRemaining(e -> fail("Should be no more elements remaining"));
assertFalse(spliterator.tryAdvance(result::add));
assertEquals(40, result.size());
assertThat(recordedEventsFrom(result), containsInOrder(reverse(events)));
}
@Test
public void splitsAndIteratesEventsBackward() {
final String stream = generateStreamName();
List<EventData> events = newTestEvents(40);
eventstore.appendToStream(stream, ExpectedVersion.NO_STREAM, events).join();
Spliterator<ResolvedEvent> spliterator =
new StreamEventsSpliterator(
StreamPosition.END, i -> eventstore.readStreamEventsBackward(stream, i, 8, false));
List<ResolvedEvent> result = new ArrayList<>();
Spliterator<ResolvedEvent> s1;
s1 = spliterator.trySplit();
assertNotNull(s1);
s1.forEachRemaining(result::add);
spliterator.forEachRemaining(result::add);
assertNull(spliterator.trySplit());
assertEquals(40, result.size());
assertThat(recordedEventsFrom(result), containsInOrder(reverse(events)));
}
@Test
public void iteratesAndSplitsEventsForward() {
final String stream = generateStreamName();
List<EventData> events = newTestEvents(17);
eventstore.appendToStream(stream, ExpectedVersion.NO_STREAM, events).join();
Spliterator<ResolvedEvent> spliterator =
new StreamEventsSpliterator(
StreamPosition.START, i -> eventstore.readStreamEventsForward(stream, i, 5, false));
List<ResolvedEvent> result = new ArrayList<>();
Spliterator<ResolvedEvent> s1, s2, s3;
assertTrue(spliterator.tryAdvance(result::add));
s1 = spliterator.trySplit();
assertNotNull(s1);
assertTrue(s1.tryAdvance(result::add));
s2 = s1.trySplit();
assertNotNull(s2);
assertTrue(s2.tryAdvance(result::add));
s2.forEachRemaining(result::add);
assertTrue(s1.tryAdvance(result::add));
s1.forEachRemaining(result::add);
assertTrue(spliterator.tryAdvance(result::add));
s3 = spliterator.trySplit();
assertNotNull(s3);
assertTrue(s3.tryAdvance(result::add));
s3.forEachRemaining(result::add);
assertTrue(spliterator.tryAdvance(result::add));
spliterator.forEachRemaining(result::add);
assertNull(spliterator.trySplit());
assertEquals(17, result.size());
assertThat(recordedEventsFrom(result), containsInOrder(events));
}
@Override
public Spliterator<R> trySplit() {
Spliterator<T> prefix = source.trySplit();
if (prefix == null) return null;
Connector<T, R> newBox = new Connector<>(null, none(), this);
synchronized (root) {
CollapseSpliterator<T, R> result = new CollapseSpliterator<>(root, prefix, left, newBox);
this.left = newBox;
return result;
}
}
/**
* Overrides AbstractTask version to include checks for early exits while splitting or computing.
*/
@Override
public void compute() {
Spliterator<P_IN> rs = spliterator, ls;
long sizeEstimate = rs.estimateSize();
long sizeThreshold = getTargetSize(sizeEstimate);
boolean forkRight = false;
@SuppressWarnings("unchecked")
K task = (K) this;
AtomicReference<R> sr = sharedResult;
R result;
while ((result = sr.get()) == null) {
if (task.taskCanceled()) {
result = task.getEmptyResult();
break;
}
if (sizeEstimate <= sizeThreshold || (ls = rs.trySplit()) == null) {
result = task.doLeaf();
break;
}
K leftChild, rightChild, taskToFork;
task.leftChild = leftChild = task.makeChild(ls);
task.rightChild = rightChild = task.makeChild(rs);
task.setPendingCount(1);
if (forkRight) {
forkRight = false;
rs = ls;
task = leftChild;
taskToFork = rightChild;
} else {
forkRight = true;
task = rightChild;
taskToFork = leftChild;
}
taskToFork.fork();
sizeEstimate = rs.estimateSize();
}
task.setLocalResult(result);
task.tryComplete();
}
@Test
public void iteratesAllRemainingEventsForwardWithoutTryAdvanceCall() {
final String stream = generateStreamName();
List<EventData> events = newTestEvents(19);
eventstore.appendToStream(stream, ExpectedVersion.NO_STREAM, events).join();
Spliterator<ResolvedEvent> spliterator =
new StreamEventsSpliterator(
StreamPosition.START, i -> eventstore.readStreamEventsForward(stream, i, 17, false));
List<ResolvedEvent> result = new ArrayList<>();
spliterator.forEachRemaining(result::add);
assertFalse(spliterator.tryAdvance(result::add));
spliterator.forEachRemaining(e -> fail("Should be no more elements remaining"));
assertNull(spliterator.trySplit());
assertEquals(19, result.size());
assertThat(recordedEventsFrom(result), containsInOrder(events));
}