[
https://issues.apache.org/jira/browse/FLINK-3703?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15428290#comment-15428290
]
ASF GitHub Bot commented on FLINK-3703:
---------------------------------------
Github user tillrohrmann commented on a diff in the pull request:
https://github.com/apache/flink/pull/2367#discussion_r75495021
--- Diff:
flink-libraries/flink-cep/src/main/java/org/apache/flink/cep/nfa/NFA.java ---
@@ -300,17 +311,21 @@ public int hashCode() {
previousEvent,
previousTimestamp,
oldVersion);
+
validPreviousState = true;
}
- // a new
computation state is referring to the shared entry
-
sharedBuffer.lock(newState, event, timestamp);
+ if
(validPreviousState) {
+ // a
new computation state is referring to the shared entry
+
sharedBuffer.lock(newState, event, timestamp);
+
+
resultingComputationStates.add(new ComputationState<T>(
+
newState,
+
event,
+
timestamp,
+
newComputationStateVersion,
+
startTimestamp));
--- End diff --
Ideally we would filtered out all computation states which referred to
pruned computations. Then we would not have to make this case distinction here.
> Add sequence matching semantics to discard matched events
> ---------------------------------------------------------
>
> Key: FLINK-3703
> URL: https://issues.apache.org/jira/browse/FLINK-3703
> Project: Flink
> Issue Type: Improvement
> Components: CEP
> Affects Versions: 1.0.0, 1.1.0
> Reporter: Till Rohrmann
> Assignee: Ivan Mushketyk
> Priority: Minor
>
> There is no easy way to decide whether events can be part of multiple
> matching sequences or not. Currently, the default is that an event can
> participate in multiple matching sequences. E.g. if you have the pattern
> {{Pattern.<Event>begin("a").followedBy("b")}} and the input event stream
> {{Event("A"), Event("B"), Event("C")}}, then you will generate the following
> matching sequences: {{Event("A"), Event("B")}}, {{Event("A"), Event("C")}}
> and {{Event("B"), Event("C")}}.
> It would be useful to allow the user to define where the matching algorithm
> should continue after a matching sequence has been found. Possible option
> values could be
> * {{from first}} - continue keeping all events for future matches (that is
> the current behaviour)
> * {{after first}} - continue after the first element (remove first matching
> event and continue with the second event)
> * {{after last}} - continue after the last element (effectively discarding
> all elements of the matching sequence)
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