org.apache.beam.sdk.transforms.windowing

Class Repeatedly

java.lang.Object

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

org.apache.beam.sdk.transforms.windowing.Repeatedly

All Implemented Interfaces:

java.io.Serializable

public class Repeatedly
extends Trigger

A Trigger that fires according to its subtrigger forever.

For example, to fire after the end of the window, and every time late data arrives:

 Repeatedly.forever(AfterWatermark.pastEndOfWindow());
 

Repeatedly.forever(someTrigger) behaves like an infinite AfterEach.inOrder(someTrigger, someTrigger, someTrigger, ...).

You can use Trigger.orFinally(OnceTrigger) to let another trigger interrupt the repetition.

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

Method Summary

Modifier and Type	Method and Description
static Repeatedly	forever(Trigger repeated) Create a composite trigger that repeatedly executes the trigger repeated, firing each time it fires and ignoring any indications to finish.
protected Trigger	getContinuationTrigger(java.util.List<Trigger> continuationTriggers) Subclasses should override this to return the Trigger.getContinuationTrigger() of this Trigger.
Trigger	getRepeatedTrigger()
Instant	getWatermarkThatGuaranteesFiring(BoundedWindow window) For internal use only; no backwards-compatibility guarantees.
boolean	mayFinish() For internal use only; no backwards-compatibility guarantees.
java.lang.String	toString()

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

equals, getContinuationTrigger, hashCode, isCompatible, orFinally, subTriggers

Methods inherited from class java.lang.Object

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

Method Detail

forever

public static Repeatedly forever(Trigger repeated)

Create a composite trigger that repeatedly executes the trigger repeated, firing each time it fires and ignoring any indications to finish.

Unless used with Trigger.orFinally(org.apache.beam.sdk.transforms.windowing.Trigger.OnceTrigger) the composite trigger will never finish.

Parameters:

repeated - the trigger to execute repeatedly.

getRepeatedTrigger

public Trigger getRepeatedTrigger()

getWatermarkThatGuaranteesFiring

public Instant getWatermarkThatGuaranteesFiring(BoundedWindow window)

Description copied from class: Trigger

For internal use only; no backwards-compatibility guarantees.

Returns a bound in event time by which this trigger would have fired at least once for a given window had there been input data.

For triggers that do not fire based on the watermark advancing, returns BoundedWindow.TIMESTAMP_MAX_VALUE.

This estimate may be used, for example, to determine that there are no elements in a side-input window, which causes the default value to be used instead.

Specified by:

getWatermarkThatGuaranteesFiring in class Trigger

mayFinish

public 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

protected Trigger getContinuationTrigger(java.util.List<Trigger> continuationTriggers)

Description copied from class: Trigger

Subclasses should override this to return the Trigger.getContinuationTrigger() of this Trigger. For convenience, this is provided the continuation trigger of each of the sub-triggers in the same order as Trigger.subTriggers.

Specified by:

getContinuationTrigger in class Trigger

Parameters:

continuationTriggers - null if Trigger.subTriggers is null, otherwise contains the result of Trigger.getContinuationTrigger() on each of the subTriggers in the same order.

toString

public java.lang.String toString()

Overrides:

toString in class Trigger