org.apache.flink.streaming.api.windowing.policy

Interface TriggerPolicy<DATA>

Type Parameters:

DATA - The data type which can be handled by this policy

All Superinterfaces:

Serializable

All Known Subinterfaces:

ActiveTriggerPolicy<DATA>, CentralActiveTrigger<DATA>, CloneableTriggerPolicy<DATA>

All Known Implementing Classes:

CloneableMultiTriggerPolicy, CountTriggerPolicy, DeltaPolicy, MultiTriggerPolicy, PunctuationPolicy, TimeTriggerPolicy

public interface TriggerPolicy<DATA>
extends Serializable

Proves and returns if a new window should be started. In case the trigger occurs (return value true) the UDF will be executed on the current element buffer without the last added element which is provided as parameter. This element will be added to the buffer after the execution of the UDF.

Method Summary

Modifier and Type	Method and Description
boolean	notifyTrigger(DATA datapoint) Proves and returns if a new window should be started.

Method Detail

notifyTrigger

boolean notifyTrigger(DATA datapoint)

Proves and returns if a new window should be started. In case the trigger occurs (return value true) the UDF will be executed on the current element buffer without the last added element which is provided as parameter. This element will be added to the buffer after the execution of the UDF. There are possibly different strategies for eviction and triggering: 1) including last data point: Better/faster for count eviction 2) excluding last data point: Essentially required for time based eviction and delta rules As 2) is required for some policies and the benefit of using 1) is small for the others, policies are implemented according to 2).

Parameters:

datapoint - the data point which arrived

Returns:

true if the current windows should be closed, otherwise false. In true case the given data point will be part of the next window and will not be included in the current one.