org.apache.flink.streaming.api.windowing.assigners.DynamicEventTimeSessionWindows 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
*
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package org.apache.flink.streaming.api.windowing.assigners;
import org.apache.flink.annotation.PublicEvolving;
import org.apache.flink.api.common.ExecutionConfig;
import org.apache.flink.api.common.typeutils.TypeSerializer;
import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;
import org.apache.flink.streaming.api.windowing.triggers.EventTimeTrigger;
import org.apache.flink.streaming.api.windowing.triggers.Trigger;
import org.apache.flink.streaming.api.windowing.windows.TimeWindow;
import java.util.Collection;
import java.util.Collections;
/**
* A {@link WindowAssigner} that windows elements into sessions based on the timestamp of the
* elements. Windows cannot overlap.
*
* For example, in order to window into windows with a dynamic time gap:
*
{@code
* DataStream> in = ...;
* KeyedStream> keyed = in.keyBy(...);
* WindowedStream, String, TimeWindows> windowed =
* keyed.window(DynamicEventTimeSessionWindows.withDynamicGap({@link SessionWindowTimeGapExtractor }));
* }
*
* @param The type of the input elements
*/
@PublicEvolving
public class DynamicEventTimeSessionWindows extends MergingWindowAssigner {
private static final long serialVersionUID = 1L;
protected SessionWindowTimeGapExtractor sessionWindowTimeGapExtractor;
protected DynamicEventTimeSessionWindows(SessionWindowTimeGapExtractor sessionWindowTimeGapExtractor) {
this.sessionWindowTimeGapExtractor = sessionWindowTimeGapExtractor;
}
@Override
public Collection assignWindows(T element, long timestamp, WindowAssignerContext context) {
long sessionTimeout = sessionWindowTimeGapExtractor.extract(element);
if (sessionTimeout <= 0) {
throw new IllegalArgumentException("Dynamic session time gap must satisfy 0 < gap");
}
return Collections.singletonList(new TimeWindow(timestamp, timestamp + sessionTimeout));
}
@SuppressWarnings("unchecked")
@Override
public Trigger getDefaultTrigger(StreamExecutionEnvironment env) {
return (Trigger) EventTimeTrigger.create();
}
@Override
public String toString() {
return "DynamicEventTimeSessionWindows()";
}
/**
* Creates a new {@code SessionWindows} {@link WindowAssigner} that assigns
* elements to sessions based on the element timestamp.
*
* @param sessionWindowTimeGapExtractor The extractor to use to extract the time gap from the input elements
* @return The policy.
*/
public static DynamicEventTimeSessionWindows withDynamicGap(SessionWindowTimeGapExtractor sessionWindowTimeGapExtractor) {
return new DynamicEventTimeSessionWindows<>(sessionWindowTimeGapExtractor);
}
@Override
public TypeSerializer getWindowSerializer(ExecutionConfig executionConfig) {
return new TimeWindow.Serializer();
}
@Override
public boolean isEventTime() {
return true;
}
/**
* Merge overlapping {@link TimeWindow}s.
*/
public void mergeWindows(Collection windows, MergeCallback c) {
TimeWindow.mergeWindows(windows, c);
}
}