lct45 commented on a change in pull request #9157:
URL: https://github.com/apache/kafka/pull/9157#discussion_r485053442
##########
File path:
streams/src/main/java/org/apache/kafka/streams/kstream/internals/KStreamSlidingWindowAggregate.java
##########
@@ -192,29 +213,125 @@ public void processInOrder(final K key, final V value,
final long timestamp) {
//create left window for new record
if (!leftWinAlreadyCreated) {
final ValueAndTimestamp<Agg> valueAndTime;
- //there's a right window that the new record could create -->
new record's left window is not empty
- if (latestLeftTypeWindow != null) {
+ // if there's a right window that the new record could create
&& previous record falls within left window -> new record's left window is not
empty
+ if (previousRecordTimestamp != null &&
leftWindowNotEmpty(previousRecordTimestamp, timestamp)) {
valueAndTime = ValueAndTimestamp.make(leftWinAgg.value(),
timestamp);
} else {
valueAndTime = ValueAndTimestamp.make(initializer.apply(),
timestamp);
}
final TimeWindow window = new TimeWindow(timestamp -
windows.timeDifferenceMs(), timestamp);
putAndForward(window, valueAndTime, key, value, closeTime,
timestamp);
}
- //create right window for new record
if (!rightWinAlreadyCreated && rightWindowIsNotEmpty(rightWinAgg,
timestamp)) {
- final TimeWindow window = new TimeWindow(timestamp + 1,
timestamp + 1 + windows.timeDifferenceMs());
- final ValueAndTimestamp<Agg> valueAndTime =
ValueAndTimestamp.make(getValueOrNull(rightWinAgg),
Math.max(rightWinAgg.timestamp(), timestamp));
+ createCurrentRecordRightWindow(timestamp, rightWinAgg, key);
+ }
+ }
+
+ /**
+ * Created to handle records where 0 < timestamp < timeDifferenceMs.
These records would create
+ * windows with negative start times, which is not supported. Instead,
they will fall within the [0, timeDifferenceMs]
+ * window, and we will update or create their right windows as new
records come in later
+ */
+ private void processEarly(final K key, final V value, final long
timestamp, final long closeTime) {
+ // A window from [0, timeDifferenceMs] that holds all early records
+ KeyValue<Windowed<K>, ValueAndTimestamp<Agg>> combinedWindow =
null;
+ ValueAndTimestamp<Agg> rightWinAgg = null;
+ boolean rightWinAlreadyCreated = false;
+ final Set<Long> windowStartTimes = new HashSet<>();
+
+ Long previousRecordTimestamp = null;
+
+ try (
+ final KeyValueIterator<Windowed<K>, ValueAndTimestamp<Agg>>
iterator = windowStore.fetch(
+ key,
+ key,
+ Math.max(0, timestamp - 2 * windows.timeDifferenceMs()),
+ // to catch the current record's right window, if it
exists, without more calls to the store
+ timestamp + 1)
+ ) {
+ KeyValue<Windowed<K>, ValueAndTimestamp<Agg>> next;
+ while (iterator.hasNext()) {
+ next = iterator.next();
+ windowStartTimes.add(next.key.window().start());
+ final long startTime = next.key.window().start();
+ final long windowMaxRecordTimestamp =
next.value.timestamp();
+
+ if (startTime == 0) {
+ combinedWindow = next;
+ if (windowMaxRecordTimestamp < timestamp) {
+ // If maxRecordTimestamp > timestamp, the current
record is out-of-order, meaning that the
+ // previous record's right window would have been
created already by other records. This
+ // will always be true for early records, as they
all fall within [0, timeDifferenceMs].
+ previousRecordTimestamp = windowMaxRecordTimestamp;
+ }
+
+ } else if (startTime <= timestamp) {
+ rightWinAgg = next.value;
+ putAndForward(next.key.window(), next.value, key,
value, closeTime, timestamp);
+ } else if (startTime == timestamp + 1) {
+ rightWinAlreadyCreated = true;
+ }
+ }
+ }
+
+ // if there wasn't a right window agg found and we need a right
window for our new record,
+ // the current aggregate in the combined window will go in the new
record's right window
+ if (rightWinAgg == null && combinedWindow != null &&
combinedWindow.value.timestamp() > timestamp) {
+ rightWinAgg = combinedWindow.value;
+ }
+
+ //create right window for new record if needed
+ if (!rightWinAlreadyCreated && rightWindowIsNotEmpty(rightWinAgg,
timestamp)) {
+ createCurrentRecordRightWindow(timestamp, rightWinAgg, key);
+ }
+
+ //create the right window for the previous record if the previous
record exists and the window hasn't already been created
+ if (previousRecordTimestamp != null &&
!windowStartTimes.contains(previousRecordTimestamp + 1)) {
+ final TimeWindow window = new
TimeWindow(previousRecordTimestamp + 1, previousRecordTimestamp + 1 +
windows.timeDifferenceMs());
+ final ValueAndTimestamp<Agg> valueAndTime =
ValueAndTimestamp.make(initializer.apply(), timestamp);
+ putAndForward(window, valueAndTime, key, value, closeTime,
timestamp);
+ }
+
+ if (combinedWindow == null) {
+ final TimeWindow window = new TimeWindow(0,
windows.timeDifferenceMs());
+ final ValueAndTimestamp<Agg> valueAndTime =
ValueAndTimestamp.make(initializer.apply(), timestamp);
putAndForward(window, valueAndTime, key, value, closeTime,
timestamp);
+
+ } else {
+ //update the combined window with the new aggregate
+ putAndForward(combinedWindow.key.window(),
combinedWindow.value, key, value, closeTime, timestamp);
}
+
}
- private boolean rightWindowIsNotEmpty(final ValueAndTimestamp<Agg>
rightWinAgg, final long timestamp) {
- return rightWinAgg != null && rightWinAgg.timestamp() > timestamp;
+ private void createCurrentRecordRightWindow(final long timestamp,
+ final
ValueAndTimestamp<Agg> rightWinAgg,
+ final K key) {
+ final TimeWindow window = new TimeWindow(timestamp + 1, timestamp
+ 1 + windows.timeDifferenceMs());
+ windowStore.put(
+ key,
+ rightWinAgg,
+ window.start());
+ tupleForwarder.maybeForward(
+ new Windowed<>(key, window),
+ rightWinAgg.value(),
+ null,
+ rightWinAgg.timestamp());
+ }
+
+ private boolean leftWindowNotEmpty(final long previousTimestamp, final
long currentTimestamp) {
+ return currentTimestamp - windows.timeDifferenceMs() <=
previousTimestamp;
+ }
+
+ // previous record's right window does not already exist and current
record falls within previous record's right window
+ private boolean rightWindowNecessaryAndPossible(final Set<Long>
windowStartTimes,
+ final long
previousRightWindowStart,
+ final long
currentRecordTimestamp) {
+ return !windowStartTimes.contains(previousRightWindowStart) &&
previousRightWindowStart + windows.timeDifferenceMs() >= currentRecordTimestamp;
}
- private boolean isLeftWindow(final KeyValue<Windowed<K>,
ValueAndTimestamp<Agg>> window) {
- return window.key.window().end() == window.value.timestamp();
+ private boolean rightWindowIsNotEmpty(final ValueAndTimestamp<Agg>
rightWinAgg, final long timestamp) {
+ return rightWinAgg != null && rightWinAgg.timestamp() > timestamp;
Review comment:
I think the catch is that it's only _sometimes_ the aggregate that goes
in the current record's right window. Sometimes we don't use the value in
`rightWingAgg` because the right window is empty/doesn't exist, but if there
_is_ a right window aggregate, it will be in `rightWinAgg`
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