Package org.apache.flink.streaming.api.windowing.assigners

Class ProcessingTimeSessionWindows

java.lang.Object

org.apache.flink.streaming.api.windowing.assigners.WindowAssigner<T,W>

org.apache.flink.streaming.api.windowing.assigners.MergingWindowAssigner<Object,TimeWindow>

org.apache.flink.streaming.api.windowing.assigners.ProcessingTimeSessionWindows

All Implemented Interfaces:

Serializable

@PublicEvolving
public class ProcessingTimeSessionWindows
extends MergingWindowAssigner<Object,TimeWindow>

A WindowAssigner that windows elements into sessions based on the current processing time. Windows cannot overlap.

For example, in order to window into windows of 1 minute, every 10 seconds:

 DataStream<Tuple2<String, Integer>> in = ...;
 KeyedStream<String, Tuple2<String, Integer>> keyed = in.keyBy(...);
 WindowedStream<Tuple2<String, Integer>, String, TimeWindows> windowed =
   keyed.window(ProcessingTimeSessionWindows.withGap(Duration.ofMinutes(1)));
 

See Also:

• Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.flink.streaming.api.windowing.assigners.MergingWindowAssigner

MergingWindowAssigner.MergeCallback<W>

Nested classes/interfaces inherited from class org.apache.flink.streaming.api.windowing.assigners.WindowAssigner

WindowAssigner.WindowAssignerContext

Field Summary

Fields

Modifier and Type	Field	Description
protected long	sessionTimeout

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	ProcessingTimeSessionWindows(long sessionTimeout)

Method Summary

Modifier and Type	Method	Description
Collection<TimeWindow>	assignWindows(Object element, long timestamp, WindowAssigner.WindowAssignerContext context)	Returns a Collection of windows that should be assigned to the element.
Trigger<Object,TimeWindow>	getDefaultTrigger()	Returns the default trigger associated with this WindowAssigner.
TypeSerializer<TimeWindow>	getWindowSerializer(ExecutionConfig executionConfig)	Returns a TypeSerializer for serializing windows that are assigned by this WindowAssigner.
boolean	isEventTime()	Returns true if elements are assigned to windows based on event time, false otherwise.
void	mergeWindows(Collection<TimeWindow> windows, MergingWindowAssigner.MergeCallback<TimeWindow> c)	Merge overlapping TimeWindows.
String	toString()
static <T> DynamicProcessingTimeSessionWindows<T>	withDynamicGap(SessionWindowTimeGapExtractor<T> sessionWindowTimeGapExtractor)	Creates a new SessionWindows WindowAssigner that assigns elements to sessions based on the element timestamp.
static ProcessingTimeSessionWindows	withGap(Duration size)	Creates a new SessionWindows WindowAssigner that assigns elements to sessions based on the element timestamp.

Methods inherited from class java.lang.Object

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

Field Details

sessionTimeout

protected long sessionTimeout

Constructor Details

ProcessingTimeSessionWindows

protected ProcessingTimeSessionWindows(long sessionTimeout)

Method Details

assignWindows

public Collection<TimeWindow> assignWindows(Object element,
 long timestamp,
 WindowAssigner.WindowAssignerContext context)

Description copied from class: WindowAssigner

Returns a Collection of windows that should be assigned to the element.

Specified by:

assignWindows in class WindowAssigner<Object,TimeWindow>

Parameters:

element - The element to which windows should be assigned.

timestamp - The timestamp of the element.

context - The WindowAssigner.WindowAssignerContext in which the assigner operates.

getDefaultTrigger

public Trigger<Object,TimeWindow> getDefaultTrigger()

Description copied from class: WindowAssigner

Returns the default trigger associated with this WindowAssigner.

1. If you override getDefaultTrigger(), the getDefaultTrigger() will be invoked and the getDefaultTrigger(StreamExecutionEnvironment env) won't be invoked. 2. If you don't override getDefaultTrigger(), the getDefaultTrigger(StreamExecutionEnvironment env) will be invoked in the default implementation of the getDefaultTrigger().

Specified by:

getDefaultTrigger in class WindowAssigner<Object,TimeWindow>

toString

public String toString()

Overrides:

toString in class Object

withGap

public static ProcessingTimeSessionWindows withGap(Duration size)

Creates a new SessionWindows WindowAssigner that assigns elements to sessions based on the element timestamp.

Parameters:

size - The session timeout, i.e. the time gap between sessions

Returns:

The policy.

withDynamicGap

@PublicEvolving
public static <T>
DynamicProcessingTimeSessionWindows<T> withDynamicGap(SessionWindowTimeGapExtractor<T> sessionWindowTimeGapExtractor)

Creates a new SessionWindows WindowAssigner that assigns elements to sessions based on the element timestamp.

Parameters:

sessionWindowTimeGapExtractor - The extractor to use to extract the time gap from the input elements

Returns:

The policy.

getWindowSerializer

public TypeSerializer<TimeWindow> getWindowSerializer(ExecutionConfig executionConfig)

Description copied from class: WindowAssigner

Returns a TypeSerializer for serializing windows that are assigned by this WindowAssigner.

Specified by:

getWindowSerializer in class WindowAssigner<Object,TimeWindow>

isEventTime

public boolean isEventTime()

Description copied from class: WindowAssigner

Returns true if elements are assigned to windows based on event time, false otherwise.

Specified by:

isEventTime in class WindowAssigner<Object,TimeWindow>

mergeWindows

public void mergeWindows(Collection<TimeWindow> windows,
 MergingWindowAssigner.MergeCallback<TimeWindow> c)

Merge overlapping TimeWindows.

Specified by:

mergeWindows in class MergingWindowAssigner<Object,TimeWindow>

Parameters:

windows - The window candidates.

c - A callback that can be invoked to signal which windows should be merged.