org.apache.flink.streaming.api.windowing.evictors

Interface Evictor<T,W extends Window>

Type Parameters:

T - The type of elements that this Evictor can evict.

W - The type of Windows on which this Evictor can operate.

All Superinterfaces:

Serializable

All Known Implementing Classes:

CountEvictor, DeltaEvictor, TimeEvictor

@PublicEvolving
public interface Evictor<T,W extends Window>
extends Serializable

An Evictor can remove elements from a pane before it is being processed and after window evaluation was triggered by a Trigger.

A pane is the bucket of elements that have the same key (assigned by the KeySelector) and same Window. An element can be in multiple panes of it was assigned to multiple windows by the WindowAssigner. These panes all have their own instance of the Evictor.

Method Summary

Modifier and Type	Method and Description
int	evict(Iterable<StreamRecord<T>> elements, int size, W window) Computes how many elements should be removed from the pane.

Method Detail

evict

int evict(Iterable<StreamRecord<T>> elements,
          int size,
          W window)

Computes how many elements should be removed from the pane. The result specifies how many elements should be removed from the beginning.

Parameters:

elements - The elements currently in the pane.

size - The current number of elements in the pane.

window - The Window