AfterFirst (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. After August 12, 2020, you can use unsupported SDKs temporarily while you upgrade your pipelines. For more information, see Using an unsupported SDK.

For information on migrating from the 1.x SDK, see Migrating from Dataflow SDK 1.x for Java.

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 AfterFirst<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>
    • • com.google.cloud.dataflow.sdk.transforms.windowing.AfterFirst<W>

• Type Parameters:

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

  All Implemented Interfaces:

  TriggerBuilder<W>, Serializable

  ---

  
  

  @Experimental(value=TRIGGER)
  public class AfterFirst<W extends BoundedWindow>
  extends Trigger.OnceTrigger<W>

  Create a composite Trigger that fires once after at least one of its sub-triggers have fired.

  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

  • Method Summary

    All Methods Static Methods Instance Methods Concrete Methods 

    Modifier and Type	Method and Description
    Trigger.OnceTrigger<W>	getContinuationTrigger(List<Trigger<W>> continuationTriggers) Return the Trigger.getContinuationTrigger() of this Trigger.
    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.
    static <W extends BoundedWindow> Trigger.OnceTrigger<W>	of(Trigger.OnceTrigger<W>... triggers) Returns an AfterFirst Trigger with the given subtriggers.
    void	onElement(Trigger.OnElementContext c) Called immediately after an element is first incorporated into a window.
    void	onMerge(Trigger.OnMergeContext c) Called immediately after windows have been merged.
    protected void	onOnlyFiring(Trigger.TriggerContext context) Called exactly once by Trigger.OnceTrigger.onFire(com.google.cloud.dataflow.sdk.transforms.windowing.Trigger<W>.TriggerContext) when the trigger is fired.
    boolean	shouldFire(Trigger.TriggerContext context) Returns true if the current state of the trigger indicates that its condition is satisfied and it is ready to fire.
    String	toString()

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

      getContinuationTrigger, onFire

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

      buildTrigger, clear, equals, hashCode, isCompatible, orFinally, prefetchOnElement, prefetchOnFire, prefetchOnMerge, prefetchShouldFire, subTriggers

    • Methods inherited from class java.lang.Object

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

• • Method Detail

    • of

      @SafeVarargs
      public static <W extends BoundedWindow> Trigger.OnceTrigger<W> of(Trigger.OnceTrigger<W>... triggers)

      Returns an AfterFirst Trigger with the given subtriggers.

    • onElement

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

      Description copied from class: Trigger
      Called immediately after windows have been merged.

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

      A trigger such as AfterWatermark.pastEndOfWindow() may no longer be finished; it is the responsibility of the trigger itself to record this fact. It is forbidden for a trigger to become finished due to Trigger.onMerge(com.google.cloud.dataflow.sdk.transforms.windowing.Trigger<W>.OnMergeContext), as it has not yet fired the pending elements that led to it being ready to fire.

      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

    • getWatermarkThatGuaranteesFiring

      public 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>

    • getContinuationTrigger

      public Trigger.OnceTrigger<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>

    • shouldFire

      public boolean shouldFire(Trigger.TriggerContext context)
                         throws Exception

      Description copied from class: Trigger
      Returns true if the current state of the trigger indicates that its condition is satisfied and it is ready to fire.

      Specified by:

      shouldFire in class Trigger<W extends BoundedWindow>

      Throws:

      Exception

    • onOnlyFiring

      protected void onOnlyFiring(Trigger.TriggerContext context)
                           throws Exception

      Description copied from class: Trigger.OnceTrigger
      Called exactly once by Trigger.OnceTrigger.onFire(com.google.cloud.dataflow.sdk.transforms.windowing.Trigger<W>.TriggerContext) when the trigger is fired. By default, invokes Trigger.OnceTrigger.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.

      Specified by:

      onOnlyFiring in class Trigger.OnceTrigger<W extends BoundedWindow>

      Throws:

      Exception

    • toString

      public String toString()

      Overrides:

      toString in class Trigger<W extends BoundedWindow>