[FLINK-6772] Incorrect ordering of matched state events in Flink CEP

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.3.0
• Fix Version/s: 1.3.1
• Component/s: Library / CEP
• Labels: flink-rel-1.3.1-blockers
• Assignee: Kostas Kloudas
• Reporter: Tzu-Li (Gordon) Tai
• Created: 30/May/17 09:21
• Updated: 01/Oct/19 15:39
• Resolved: 08/Jun/17 14:51

Description

I've stumbled across an unexepected ordering of the matched state events.

Pattern:

Pattern<String, ?> pattern = Pattern
    .<String>begin("start")
        .where(new IterativeCondition<String>() {
            @Override
            public boolean filter(String s, Context<String> context) throws Exception {
                return s.startsWith("a-");
            }
        }).times(4).allowCombinations()
    .followedByAny("end")
        .where(new IterativeCondition<String>() {
            public boolean filter(String s, Context<String> context) throws Exception {
                return s.startsWith("b-");
            }
    }).times(3).consecutive();

Input event sequence:
a-1, a-2, a-3, a-4, b-1, b-2, b-3

On b-3 a matched pattern would be triggered.

Now, in the Map<String, List<IN>> map passed via select in PatternSelectFunction, the list for the "end" state is:
b-3, b-1, b-2.

Based on the timestamp of the events (simply using processing time), the correct order should be b-1, b-2, b-3.

Issue Links

• links to: GitHub Pull Request #4084