Trigger.OnceTrigger (Google Cloud Dataflow SDK 1.9.1 API)

Google Cloud Dataflow SDK for Java, version 1.9.1

Warning: Dataflow SDK 1.x for Java is unsupported as of October 16, 2018. See Migrating from Dataflow SDK 1.x for Java for migration guidance.

Note: If you are using Cloud Dataflow SDK version 2.x, see the Apache Beam API reference documentation.

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

Class Trigger.OnceTrigger<W extends BoundedWindow>

• java.lang.Object
• • com.google.cloud.dataflow.sdk.transforms.windowing.Trigger<W>
  • • com.google.cloud.dataflow.sdk.transforms.windowing.Trigger.OnceTrigger<W>

• Type Parameters:

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

  All Implemented Interfaces:

  TriggerBuilder<W>, Serializable

  Direct Known Subclasses:

  AfterAll, AfterDelayFromFirstElement, AfterFirst, AfterPane, AfterWatermark.FromEndOfWindow

  Enclosing class:

  Trigger<W extends BoundedWindow>

  ---

  
  

  public abstract static class Trigger.OnceTrigger<W extends BoundedWindow>
  extends Trigger<W>

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

  See Also:

  Serialized Form

• • Nested Class Summary

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

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

  • Field Summary

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

      subTriggers

  • Constructor Summary

    Constructors 

    Modifier	Constructor and Description
    protected	OnceTrigger(List<Trigger<W>> subTriggers)

  • Method Summary

    All Methods Instance Methods Abstract Methods Concrete Methods 

    Modifier and Type	Method and Description
    Trigger.OnceTrigger<W>	getContinuationTrigger() Return a trigger to use after a GroupByKey to preserve the intention of this trigger.
    void	onFire(Trigger.TriggerContext context) Adjusts the state of the trigger to be ready for the next pane.
    protected abstract void	onOnlyFiring(Trigger.TriggerContext context) Called exactly once by onFire(com.google.cloud.dataflow.sdk.transforms.windowing.Trigger<W>.TriggerContext) when the trigger is fired.

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

      buildTrigger, clear, equals, getContinuationTrigger, getWatermarkThatGuaranteesFiring, hashCode, isCompatible, onElement, onMerge, orFinally, prefetchOnElement, prefetchOnFire, prefetchOnMerge, prefetchShouldFire, shouldFire, subTriggers, toString

    • Methods inherited from class java.lang.Object

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

• • Constructor Detail

    • OnceTrigger

      protected OnceTrigger(List<Trigger<W>> subTriggers)

  • Method Detail

    • getContinuationTrigger

      public final Trigger.OnceTrigger<W> 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).

      Overrides:

      getContinuationTrigger in class Trigger<W extends BoundedWindow>

    • onFire

      public final void onFire(Trigger.TriggerContext context)
                        throws Exception

      Adjusts the state of the trigger to be ready for the next pane. For example, a Repeatedly trigger will reset its inner trigger, since it has fired.

      If the trigger is finished, it is the responsibility of the trigger itself to record that fact via the context.

      Specified by:

      onFire in class Trigger<W extends BoundedWindow>

      Throws:

      Exception

    • onOnlyFiring

      protected abstract void onOnlyFiring(Trigger.TriggerContext context)
                                    throws Exception

      Called exactly once by onFire(com.google.cloud.dataflow.sdk.transforms.windowing.Trigger<W>.TriggerContext) when the trigger is fired. By default, invokes onFire(com.google.cloud.dataflow.sdk.transforms.windowing.Trigger<W>.TriggerContext) on all subtriggers for which Trigger.shouldFire(com.google.cloud.dataflow.sdk.transforms.windowing.Trigger<W>.TriggerContext) is true.

      Throws:

      Exception