Github user dianfu commented on a diff in the pull request:
https://github.com/apache/flink/pull/4331#discussion_r130266394
--- Diff:
flink-libraries/flink-cep/src/main/java/org/apache/flink/cep/nfa/NFA.java ---
@@ -551,18 +579,47 @@ private boolean isSelfIgnore(final StateTransition<T>
edge) {
nextVersion,
startTimestamp);
}
+
+ switch (skipStrategy.getStrategy()) {
+ case SKIP_PAST_LAST_EVENT:
+ if
(nextState.isFinal()) {
+
resultingComputationStates.add(createStartComputationState(computationState,
event));
+ }
+ break;
+ case SKIP_TO_FIRST:
+ if
(nextState.getName().equals(skipStrategy.getPatternName()) &&
+
!nextState.getName().equals(currentState.getName())) {
+
ComputationState<T> startComputationState =
createStartComputationState(computationState, event);
+ if (callLevel >
0) {
+ throw
new RuntimeException("infinite loop! Will abort the match process, please
rewrite your pattern query");
+ }
+ // feed current
matched event to the state.
+
Collection<ComputationState<T>> computationStates =
computeNextStates(startComputationState, event, timestamp, callLevel++);
+
resultingComputationStates.addAll(computationStates);
+ } else if
(previousState == null &&
currentState.getName().equals(skipStrategy.getPatternName())) {
+ throw new
RuntimeException("infinite loop! Will abort the match process, please rewrite
your pattern query");
+ }
+ break;
+ case SKIP_TO_LAST:
+ if
(currentState.getName().equals(skipStrategy.getPatternName()) &&
+
!nextState.getName().equals(currentState.getName())) {
+
ComputationState<T> startComputationState =
createStartComputationState(computationState, event);
+ if (callLevel >
0) {
+ throw
new RuntimeException("infinite loop! Will abort the match process, please
rewrite your pattern query");
+ }
+ // feed current
matched event to the state.
+
Collection<ComputationState<T>> computationStates =
computeNextStates(startComputationState, event, timestamp, callLevel++);
+
resultingComputationStates.addAll(computationStates);
+ }
+ break;
+ }
break;
}
}
- if (computationState.isStartState()) {
- int totalBranches = calculateIncreasingSelfState(
- outgoingEdges.getTotalIgnoreBranches(),
- outgoingEdges.getTotalTakeBranches());
-
- DeweyNumber startVersion =
computationState.getVersion().increase(totalBranches);
- ComputationState<T> startState =
ComputationState.createStartState(this, computationState.getState(),
startVersion);
- resultingComputationStates.add(startState);
+ if (computationState.isStartState() &&
+ skipStrategy.getStrategy() ==
AfterMatchSkipStrategy.SkipStrategy.SKIP_TO_NEXT_EVENT) {
--- End diff --
If the skip strategy is @**SKIP_PAST_LAST_EVENT**, for pattern **a nextby
b** and inputs **a1 c a2 b2**, the output should be **a2 b2**, but per the
current implementation, I'm afraid there will be no output as after **a1** is
processed, the start ComputationState will be consumed, but there is no chance
to add the start ComputationState later and so **a2 b2** can not be matched.
Right? For other skip strategy, I'm afraid there may be also such issues.
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