org.apache.flink.streaming.api.windowing.triggers

Class DeltaTrigger<T,W extends Window>

java.lang.Object

org.apache.flink.streaming.api.windowing.triggers.Trigger<T,W>

org.apache.flink.streaming.api.windowing.triggers.DeltaTrigger<T,W>

Type Parameters:

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

All Implemented Interfaces:

Serializable

@PublicEvolving
public class DeltaTrigger<T,W extends Window>
extends Trigger<T,W>

A Trigger that fires based on a DeltaFunction and a threshold.

This trigger calculates a delta between the data point which triggered last and the currently arrived data point. It triggers if the delta is higher than a specified threshold.

See Also:

Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.flink.streaming.api.windowing.triggers.Trigger

Trigger.OnMergeContext, Trigger.TriggerContext

Method Summary

Modifier and Type	Method and Description
void	clear(W window, Trigger.TriggerContext ctx) Clears any state that the trigger might still hold for the given window.
static <T,W extends Window> DeltaTrigger<T,W>	of(double threshold, DeltaFunction<T> deltaFunction, TypeSerializer<T> stateSerializer) Creates a delta trigger from the given threshold and DeltaFunction.
TriggerResult	onElement(T element, long timestamp, W window, Trigger.TriggerContext ctx) Called for every element that gets added to a pane.
TriggerResult	onEventTime(long time, W window, Trigger.TriggerContext ctx) Called when an event-time timer that was set using the trigger context fires.
TriggerResult	onProcessingTime(long time, W window, Trigger.TriggerContext ctx) Called when a processing-time timer that was set using the trigger context fires.
String	toString()

Methods inherited from class org.apache.flink.streaming.api.windowing.triggers.Trigger

canMerge, onMerge

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Method Detail

onElement

public TriggerResult onElement(T element,
                               long timestamp,
                               W window,
                               Trigger.TriggerContext ctx)
                        throws Exception

Description copied from class: Trigger

Called for every element that gets added to a pane. The result of this will determine whether the pane is evaluated to emit results.

Specified by:

onElement in class Trigger<T,W extends Window>

Parameters:

element - The element that arrived.

timestamp - The timestamp of the element that arrived.

window - The window to which the element is being added.

ctx - A context object that can be used to register timer callbacks.

Throws:

Exception

onEventTime

public TriggerResult onEventTime(long time,
                                 W window,
                                 Trigger.TriggerContext ctx)

Description copied from class: Trigger

Called when an event-time timer that was set using the trigger context fires.

Specified by:

onEventTime in class Trigger<T,W extends Window>

Parameters:

time - The timestamp at which the timer fired.

window - The window for which the timer fired.

ctx - A context object that can be used to register timer callbacks.

onProcessingTime

public TriggerResult onProcessingTime(long time,
                                      W window,
                                      Trigger.TriggerContext ctx)
                               throws Exception

Description copied from class: Trigger

Called when a processing-time timer that was set using the trigger context fires.

Specified by:

onProcessingTime in class Trigger<T,W extends Window>

Parameters:

time - The timestamp at which the timer fired.

window - The window for which the timer fired.

ctx - A context object that can be used to register timer callbacks.

Throws:

Exception

clear

public void clear(W window,
                  Trigger.TriggerContext ctx)
           throws Exception

Description copied from class: Trigger

Clears any state that the trigger might still hold for the given window. This is called when a window is purged. Timers set using Trigger.TriggerContext.registerEventTimeTimer(long) and Trigger.TriggerContext.registerProcessingTimeTimer(long) should be deleted here as well as state acquired using Trigger.TriggerContext.getPartitionedState(StateDescriptor).

Specified by:

clear in class Trigger<T,W extends Window>

Throws:

Exception

toString

public String toString()

Overrides:

toString in class Object

of

public static <T,W extends Window> DeltaTrigger<T,W> of(double threshold,
                                                        DeltaFunction<T> deltaFunction,
                                                        TypeSerializer<T> stateSerializer)

Creates a delta trigger from the given threshold and DeltaFunction.

Type Parameters:

T - The type of elements on which this trigger can operate.

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

Parameters:

threshold - The threshold at which to trigger.

deltaFunction - The delta function to use

stateSerializer - TypeSerializer for the data elements.