org.apache.beam.sdk.transforms.windowing

Class Trigger.OnceTrigger

java.lang.Object

org.apache.beam.sdk.transforms.windowing.Trigger

org.apache.beam.sdk.transforms.windowing.Trigger.OnceTrigger

All Implemented Interfaces:

java.io.Serializable

Direct Known Subclasses:

AfterAll, AfterFirst, AfterPane, AfterProcessingTime, AfterSynchronizedProcessingTime, AfterWatermark.FromEndOfWindow, Never.NeverTrigger

Enclosing class:

Trigger

@Internal
public abstract static class Trigger.OnceTrigger
extends Trigger

For internal use only; no backwards-compatibility guarantees.

Triggers that are guaranteed to fire at most once should extend Trigger.OnceTrigger rather than the general Trigger class to indicate that behavior.

See Also:

Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.beam.sdk.transforms.windowing.Trigger

Trigger.OnceTrigger

Field Summary

Fields inherited from class org.apache.beam.sdk.transforms.windowing.Trigger

subTriggers

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	OnceTrigger(java.util.List<Trigger> subTriggers)

Method Summary

Modifier and Type	Method and Description
Trigger.OnceTrigger	getContinuationTrigger() Return a trigger to use after a GroupByKey to preserve the intention of this trigger.
boolean	mayFinish() For internal use only; no backwards-compatibility guarantees.

Methods inherited from class org.apache.beam.sdk.transforms.windowing.Trigger

equals, getContinuationTrigger, getWatermarkThatGuaranteesFiring, hashCode, isCompatible, orFinally, subTriggers, toString

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

OnceTrigger

protected OnceTrigger(@Nullable
                      java.util.List<Trigger> subTriggers)

Method Detail

mayFinish

public final boolean mayFinish()

Description copied from class: Trigger

For internal use only; no backwards-compatibility guarantees.

Indicates whether this trigger may "finish". A top level trigger that finishes can cause data loss, so is rejected by GroupByKey validation.

Specified by:

mayFinish in class Trigger

getContinuationTrigger

public final Trigger.OnceTrigger getContinuationTrigger()

Description copied from class: Trigger

Return a trigger to use after a GroupByKey to preserve the intention of this trigger. Specifically, triggers that are time based and intended to provide speculative results should continue providing speculative results. Triggers that fire once (or multiple times) should continue firing once (or multiple times).

If this method is not overridden, its default implementation delegates its behavior to Trigger.getContinuationTrigger(List) which is expected to be implemented by subclasses.

Overrides:

getContinuationTrigger in class Trigger