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https://issues.apache.org/jira/browse/FLINK-6772?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16029303#comment-16029303
]
Tzu-Li (Gordon) Tai commented on FLINK-6772:
--------------------------------------------
So, for example,
{code}
public class FlinkCEPTest {
public static void main(String[] args) throws Exception {
StreamExecutionEnvironment env =
StreamExecutionEnvironment.getExecutionEnvironment();
env.setParallelism(2);
DataStream<String> input = env.fromElements(
"a-1", "a-2", "a-3", "a-4", "b-1", "b-2", "b-3"
);
Pattern<String, ?> pattern = Pattern
.<String>begin("start")
.where(new SimpleCondition<String>() {
public boolean filter(String s) throws
Exception {
return s.startsWith("a-");
}
}).times(4).allowCombinations()
.followedByAny("randomStateName")
.where(new SimpleCondition<String>() {
public boolean filter(String s) throws
Exception {
return s.startsWith("b-");
}
}).times(3).consecutive();
CEP.pattern(input, pattern).select(new
PatternSelectFunction<String, String>() {
public String select(Map<String, List<String>> pattern)
throws Exception {
return pattern.toString();
}
}).print();
env.execute();
}
}
{code}
The result is:
{code}
1> {randomStateName=[b-3, b-1, b-2], start=[a-1, a-2, a-3, a-4]}
{code}
> Incorrect ordering of matched state events in Flink CEP
> -------------------------------------------------------
>
> Key: FLINK-6772
> URL: https://issues.apache.org/jira/browse/FLINK-6772
> Project: Flink
> Issue Type: Bug
> Components: CEP
> Reporter: Tzu-Li (Gordon) Tai
>
> I've stumbled across an unexepected ordering of the matched state events.
> Pattern:
> {code}
> 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();
> {code}
> 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.
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