com.google.cloud.dataflow.sdk.transforms.windowing

Class Repeatedly<W extends BoundedWindow>

java.lang.Object

com.google.cloud.dataflow.sdk.transforms.windowing.Trigger<W>

com.google.cloud.dataflow.sdk.transforms.windowing.Repeatedly<W>

Type Parameters:

W - BoundedWindow subclass used to represent the windows used by this Trigger

All Implemented Interfaces:

java.io.Serializable

public class Repeatedly<W extends BoundedWindow>
extends Trigger<W>

Repeat a trigger, either until some condition is met or forever.

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

 Repeatedly.forever(AfterWatermark.isPastEndOfWindow());
  

Repeatedly.forever(someTrigger) behaves like the infinite SequenceOf(someTrigger, someTrigger, someTrigger, ...).

See Also:

Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class com.google.cloud.dataflow.sdk.transforms.windowing.Trigger

Trigger.OnceTrigger<W extends BoundedWindow>, Trigger.OnElementEvent<W>, Trigger.OnMergeEvent<W>, Trigger.OnTimerEvent<W extends BoundedWindow>, Trigger.TimeDomain, Trigger.TriggerContext<W extends BoundedWindow>, Trigger.TriggerId<W extends BoundedWindow>, Trigger.TriggerResult, Trigger.WindowStatus

Method Summary

Methods

Modifier and Type	Method and Description
void	clear(Trigger.TriggerContext<W> c, W window) Clear any state associated with this trigger in the given window.
static <W extends BoundedWindow> Repeatedly<W>	forever(Trigger<W> repeated) Create a composite trigger that repeatedly executes the trigger toRepeat, firing each time it fires and ignoring any indications to finish.
Instant	getWatermarkCutoff(W window) Returns a bound in watermark time by which this trigger would have fired at least once for a given window had there been input data.
boolean	isCompatible(Trigger<?> other) Returns whether this performs the same triggering as the given Trigger.
Trigger.TriggerResult	onElement(Trigger.TriggerContext<W> c, Trigger.OnElementEvent<W> e) Called immediately after an element is first incorporated into a window.
Trigger.TriggerResult	onMerge(Trigger.TriggerContext<W> c, Trigger.OnMergeEvent<W> e) Called immediately after windows have been merged.
Trigger.TriggerResult	onTimer(Trigger.TriggerContext<W> c, Trigger.OnTimerEvent<W> e) Called when a timer has fired for the trigger or one of it’s sub-triggers.
boolean	willNeverFinish() Return true if the trigger is guaranteed to never finish.

Methods inherited from class com.google.cloud.dataflow.sdk.transforms.windowing.Trigger

orFinally

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

forever

public static <W extends BoundedWindow> Repeatedly<W> forever(Trigger<W> repeated)

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

Unless used with Trigger.orFinally(com.google.cloud.dataflow.sdk.transforms.windowing.Trigger.OnceTrigger<W>) the composite trigger will never finish.

Parameters:

repeated - the trigger to execute repeatedly.

onElement

public Trigger.TriggerResult onElement(Trigger.TriggerContext<W> c,
                              Trigger.OnElementEvent<W> e)
                                throws java.lang.Exception

Description copied from class: Trigger

Called immediately after an element is first incorporated into a window.

Specified by:

onElement in class Trigger<W extends BoundedWindow>

Parameters:

c - the context to interact with

e - an event describing the cause of this callback being executed

Throws:

java.lang.Exception

onMerge

public Trigger.TriggerResult onMerge(Trigger.TriggerContext<W> c,
                            Trigger.OnMergeEvent<W> e)
                              throws java.lang.Exception

Description copied from class: Trigger

Called immediately after windows have been merged.

This will only be called if the trigger hasn't finished in any of the oldWindows. If it had finished, we assume that it is also finished in the resulting window.

The implementation does not need to clear out any state associated with the old windows. That will automatically be done by the trigger execution layer.

Specified by:

onMerge in class Trigger<W extends BoundedWindow>

Parameters:

c - the context to interact with

e - an event describnig the cause of this callback being executed

Throws:

java.lang.Exception

onTimer

public Trigger.TriggerResult onTimer(Trigger.TriggerContext<W> c,
                            Trigger.OnTimerEvent<W> e)
                              throws java.lang.Exception

Description copied from class: Trigger

Called when a timer has fired for the trigger or one of it’s sub-triggers.

Specified by:

onTimer in class Trigger<W extends BoundedWindow>

Parameters:

c - the context to interact with

e - identifier for the trigger that the timer is for.

Throws:

java.lang.Exception

clear

public void clear(Trigger.TriggerContext<W> c,
         W window)
           throws java.lang.Exception

Description copied from class: Trigger

Clear any state associated with this trigger in the given window.

This is called after a trigger has indicated it will never fire again. The trigger system keeps enough information to know that the trigger is finished, so this trigger should clear all of its state.

Specified by:

clear in class Trigger<W extends BoundedWindow>

Parameters:

c - the context to interact with

window - the window that is being cleared

Throws:

java.lang.Exception

willNeverFinish

public boolean willNeverFinish()

Description copied from class: Trigger

Return true if the trigger is guaranteed to never finish.

Overrides:

willNeverFinish in class Trigger<W extends BoundedWindow>

getWatermarkCutoff

public Instant getWatermarkCutoff(W window)

Description copied from class: Trigger

Returns a bound in watermark time by which this trigger would have fired at least once for a given window had there been input data. This is a static property of a trigger that does not depend on its state.

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

Specified by:

getWatermarkCutoff in class Trigger<W extends BoundedWindow>

isCompatible

public boolean isCompatible(Trigger<?> other)

Description copied from class: Trigger

Returns whether this performs the same triggering as the given Trigger.

Specified by:

isCompatible in class Trigger<W extends BoundedWindow>