org.apache.flink.cep.functions.TimedOutPartialMatchHandler Maven / Gradle / Ivy
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* to you under the Apache License, Version 2.0 (the
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* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
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*/
package org.apache.flink.cep.functions;
import org.apache.flink.annotation.PublicEvolving;
import java.time.Duration;
import java.util.List;
import java.util.Map;
/**
* Enables handling timed out partial matches. It shall be used in a mixin style. If you need your
* {@link PatternProcessFunction} to be able to handle timed out partial matches implement this
* interface as well. Example:
*
* {@code
* private class MyFunction extends PatternProcessFunction implements TimedOutPartialMatchHandler {
*
* }
* }
*
* @param type of input elements
*/
@PublicEvolving
public interface TimedOutPartialMatchHandler {
/**
* Called for every timed out partial match (due to {@link
* org.apache.flink.cep.pattern.Pattern#within(Duration)}). It enables custom handling, e.g. one
* can emit the timed out results through a side output:
*
* {@code
* private final OutputTag timedOutPartialMatchesTag = ...
*
* private class MyFunction extends PatternProcessFunction implements TimedOutPartialMatchHandler {
*
* @Override
* public void processMatch(Map> match, Context ctx, Collector out) throws Exception {
* ...
* }
*
* @Override
* void processTimedOutMatch(Map> match, PatternProcessFunction.Context ctx) throws Exception {
* ctx.output(timedOutPartialMatchesTag, match);
* }
* }
* }
*
* {@link PatternProcessFunction.Context#timestamp()} in this case returns the minimal time
* in which we can say that the partial match will not become a match, which is effectively the
* timestamp of the first element assigned to the partial match plus the value of within.
*
* @param match map containing the timed out partial match. Events are identified by their
* names.
* @param ctx enables access to time features and emitting results through side outputs
* @throws Exception This method may throw exceptions. Throwing an exception will cause the
* operation to fail and may trigger recovery.
*/
void processTimedOutMatch(
final Map> match, final PatternProcessFunction.Context ctx)
throws Exception;
}