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

Class DefaultTrigger<W extends BoundedWindow>

java.lang.Object

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

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

Type Parameters:

W - The type of windows being triggered/encoded.

All Implemented Interfaces:

Serializable

@Experimental(value=TRIGGER)
public class DefaultTrigger<W extends BoundedWindow>
extends Trigger<W>

A trigger that is equivalent to Repeatedly.forever(AfterWatermark.pastEndOfWindow()). See Repeatedly.forever(com.google.cloud.dataflow.sdk.transforms.windowing.Trigger<W>) and AfterWatermark.pastEndOfWindow() for more details.

See Also:

Serialized Form

Nested Class Summary

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

Trigger.MergeResult, Trigger.MergingTriggerInfo<W extends BoundedWindow>, Trigger.OnceTrigger<W extends BoundedWindow>, Trigger.OnElementContext, Trigger.OnMergeContext, Trigger.OnTimerContext, Trigger.TriggerContext, Trigger.TriggerInfo<W extends BoundedWindow>, Trigger.TriggerResult

Field Summary

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

subTriggers

Method Summary

Modifier and Type	Method and Description
void	clear(Trigger.TriggerContext c) Clear any state associated with this trigger in the given window.
Trigger<W>	getContinuationTrigger(List<Trigger<W>> continuationTriggers) Return the Trigger.getContinuationTrigger() of this Trigger.
org.joda.time.Instant	getWatermarkThatGuaranteesFiring(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.
static <W extends BoundedWindow> DefaultTrigger<W>	of() Returns the default trigger.
Trigger.TriggerResult	onElement(Trigger.OnElementContext c) Called immediately after an element is first incorporated into a window.
Trigger.MergeResult	onMerge(Trigger.OnMergeContext c) Called immediately after windows have been merged.
Trigger.TriggerResult	onTimer(Trigger.OnTimerContext c) Called when a timer has fired for the current window.

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

equals, getContinuationTrigger, hashCode, orFinally, prefetchOnElement, prefetchOnMerge, prefetchOnTimer, subTriggers, toString

Methods inherited from class java.lang.Object

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

Method Detail

of

public static <W extends BoundedWindow> DefaultTrigger<W> of()

Returns the default trigger.

onElement

public Trigger.TriggerResult onElement(Trigger.OnElementContext c)
                                throws 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>

Throws:

Exception

onMerge

public Trigger.MergeResult onMerge(Trigger.OnMergeContext c)
                            throws Exception

Description copied from class: Trigger

Called immediately after windows have been merged.

Leaf triggers should determine their result by inspecting their status and any state in the merging windows. Composite triggers should determine their result by calling ExecutableTrigger.invokeMerge(com.google.cloud.dataflow.sdk.transforms.windowing.Trigger<W>.OnMergeContext) on their sub-triggers, and applying appropriate logic.

A trigger can only return Trigger.MergeResult.ALREADY_FINISHED if it is marked as finished in at least one of the windows being merged.

The implementation does not need to clear out any state associated with the old windows.

Specified by:

onMerge in class Trigger<W extends BoundedWindow>

Throws:

Exception

onTimer

public Trigger.TriggerResult onTimer(Trigger.OnTimerContext c)
                              throws Exception

Description copied from class: Trigger

Called when a timer has fired for the current window. Composite triggers should pass the event to all sub-triggers. Triggers that set timers should verify the timer matches what they set before processing the firing.

Specified by:

onTimer in class Trigger<W extends BoundedWindow>

Throws:

Exception

clear

public void clear(Trigger.TriggerContext c)
           throws 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.

Overrides:

clear in class Trigger<W extends BoundedWindow>

Throws:

Exception

getWatermarkThatGuaranteesFiring

public org.joda.time.Instant getWatermarkThatGuaranteesFiring(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.

This estimate is used 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<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.

Overrides:

isCompatible in class Trigger<W extends BoundedWindow>

getContinuationTrigger

public Trigger<W> getContinuationTrigger(List<Trigger<W>> continuationTriggers)

Description copied from class: Trigger

Return the Trigger.getContinuationTrigger() of this Trigger. For convenience, this is provided the continuation trigger of each of the sub-triggers.

Specified by:

getContinuationTrigger in class Trigger<W extends BoundedWindow>