org.apache.flink.streaming.api.windowing.helper

Class Count

java.lang.Object

org.apache.flink.streaming.api.windowing.helper.WindowingHelper

org.apache.flink.streaming.api.windowing.helper.Count

public class Count
extends WindowingHelper

Represents a count based trigger or eviction policy. Use the of(int) to get an instance.

Field Summary

Fields inherited from class org.apache.flink.streaming.api.windowing.helper.WindowingHelper

executionConfig

Constructor Summary

Constructors

Constructor and Description
Count(int count) Specifies on which element a trigger or an eviction should happen (based on the count of the elements).

Method Summary

Modifier and Type	Method and Description
static Count	of(int count) Specifies a count based eviction (window size) or trigger policy (slide size).
Count	startingAt(int startValue) Sets the initial value of the counter.
EvictionPolicy<?>	toEvict() Method for encapsulating the EvictionPolicy.
TriggerPolicy<?>	toTrigger() Method for encapsulating the TriggerPolicy.
Count	withDelete(int deleteOnEviction) Sets the number of elements deleted at each eviction (i.e when the number elements exceeds the window size).

Methods inherited from class org.apache.flink.streaming.api.windowing.helper.WindowingHelper

setExecutionConfig

Methods inherited from class java.lang.Object

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

Constructor Detail

Count

public Count(int count)

Specifies on which element a trigger or an eviction should happen (based on the count of the elements). This constructor does exactly the same as of(int).

Parameters:

count - the number of elements to count before trigger/evict

Method Detail

toEvict

public EvictionPolicy<?> toEvict()

Description copied from class: WindowingHelper

Method for encapsulating the EvictionPolicy.

Specified by:

toEvict in class WindowingHelper

Returns:

the eviction policy

toTrigger

public TriggerPolicy<?> toTrigger()

Description copied from class: WindowingHelper

Method for encapsulating the TriggerPolicy.

Specified by:

toTrigger in class WindowingHelper

Returns:

the trigger policy

withDelete

public Count withDelete(int deleteOnEviction)

Sets the number of elements deleted at each eviction (i.e when the number elements exceeds the window size). By default the elements get deleted one by one (deleteOnEvition = 1)

Parameters:

deleteOnEviction - The number of elements deleted at each evition

Returns:

Helper representing the count based policy

startingAt

public Count startingAt(int startValue)

Sets the initial value of the counter. 0 by default

Parameters:

startValue - Starting value of the window counter

Returns:

Helper representing the count based policy

of

public static Count of(int count)

Specifies a count based eviction (window size) or trigger policy (slide size). For eviction 'count' defines the number of elements in each window. For trigger 'count' defines how often do we call the user function in terms of number of elements received.

Parameters:

count - the number of elements to count before trigger/evict

Returns:

Helper representing the count based policy