Github user kl0u commented on a diff in the pull request:
https://github.com/apache/flink/pull/3644#discussion_r108958127
--- Diff:
flink-libraries/flink-cep/src/main/java/org/apache/flink/cep/operator/AbstractKeyedCEPPatternOperator.java
---
@@ -196,19 +213,45 @@ public void processElement(StreamRecord<IN> element)
throws Exception {
updateNFA(nfa);
} else {
-
getInternalWatermarkCallbackService().registerKeyForWatermarkCallback(keySelector.getKey(element.getValue()));
- PriorityQueue<StreamRecord<IN>> priorityQueue =
getPriorityQueue();
+ // In event-time processing we assume correctness of
the watermark.
+ // Events with timestamp smaller than the last seen
watermark are considered late.
+ // Late events are put in a dedicated side output, if
the user has specified one.
+
+ if (element.getTimestamp() >= lastWatermark) {
- // event time processing
- // we have to buffer the elements until we receive the
proper watermark
- if (getExecutionConfig().isObjectReuseEnabled()) {
- // copy the StreamRecord so that it cannot be
changed
- priorityQueue.offer(new
StreamRecord<IN>(inputSerializer.copy(element.getValue()),
element.getTimestamp()));
+ // we have an event with a valid timestamp, so
+ // we buffer it until we receive the proper
watermark.
+
+
getInternalWatermarkCallbackService().registerKeyForWatermarkCallback(keySelector.getKey(element.getValue()));
+
+ PriorityQueue<StreamRecord<IN>> priorityQueue =
getPriorityQueue();
+ if
(getExecutionConfig().isObjectReuseEnabled()) {
+ // copy the StreamRecord so that it
cannot be changed
+ priorityQueue.offer(new
StreamRecord<>(inputSerializer.copy(element.getValue()),
element.getTimestamp()));
+ } else {
+ priorityQueue.offer(element);
+ }
+ updatePriorityQueue(priorityQueue);
} else {
- priorityQueue.offer(element);
+ sideOutputLateElement(element);
}
- updatePriorityQueue(priorityQueue);
+ }
+ }
+
+ private void updateLastSeenWatermark(Watermark watermark) {
+ this.lastWatermark = watermark.getTimestamp();
--- End diff --
I believe that the `Watermark` handling should be the responsibility of the
sources. Checkpointing it here would mean special logic for handling it in case
of scaling down for example. In addition, when scaling down e.g from 2 tasks to
1 and the 2 tasks had different last watermarks, then we still may have issues
with elements being processed out-of-order.
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