Package org.apache.beam.sdk.transforms.windowing

Class DefaultTrigger

java.lang.Object
org.apache.beam.sdk.transforms.windowing.Trigger
org.apache.beam.sdk.transforms.windowing.DefaultTrigger
All Implemented Interfaces:
Serializable
public class DefaultTrigger extends Trigger
A trigger that is equivalent to Repeatedly.forever(AfterWatermark.pastEndOfWindow()). See Repeatedly.forever(org.apache.beam.sdk.transforms.windowing.Trigger) and AfterWatermark.pastEndOfWindow() for more details.

This is a distinguished class to make it easy for runners to optimize for this common case.

See Also:

  • Method Details

    • of

      public static DefaultTrigger of()
      Returns the default trigger.

    • 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
      Returns:
      false; the default trigger never finishes

    • isCompatible

      public boolean isCompatible(Trigger other)
      Description copied from class: Trigger
      For internal use only; no backwards-compatibility guarantees.

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

      Overrides:
      isCompatible in class Trigger

    • getContinuationTrigger

      protected Trigger getContinuationTrigger(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 - contains the result of Trigger.getContinuationTrigger() on each of the subTriggers in the same order.