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/after the evaluation of WindowFunction and after the window evaluation gets 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.

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static interface	Evictor.EvictorContext A context object that is given to Evictor methods.

Method Summary

Modifier and Type	Method and Description
void	evictAfter(Iterable<TimestampedValue<T>> elements, int size, W window, Evictor.EvictorContext evictorContext) Optionally evicts elements.
void	evictBefore(Iterable<TimestampedValue<T>> elements, int size, W window, Evictor.EvictorContext evictorContext) Optionally evicts elements.

Method Detail

evictBefore

void evictBefore(Iterable<TimestampedValue<T>> elements,
                 int size,
                 W window,
                 Evictor.EvictorContext evictorContext)

Optionally evicts elements. Called before windowing function.

Parameters:

elements - The elements currently in the pane.

size - The current number of elements in the pane.

window - The Window

evictorContext - The context for the Evictor

evictAfter

void evictAfter(Iterable<TimestampedValue<T>> elements,
                int size,
                W window,
                Evictor.EvictorContext evictorContext)

Optionally evicts elements. Called after windowing function.

Parameters:

elements - The elements currently in the pane.

size - The current number of elements in the pane.

window - The Window

evictorContext - The context for the Evictor