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

Class EventTimeSessionWindows

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.EventTimeSessionWindows

All Implemented Interfaces:

Serializable

public class EventTimeSessionWindows
extends MergingWindowAssigner<Object,TimeWindow>

A WindowAssigner that windows elements into sessions based on the timestamp of the elements. 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(EventTimeSessionWindows.withGap(Time.minutes(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 and Description
protected long	sessionTimeout

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	EventTimeSessionWindows(long sessionTimeout)

Method Summary

Modifier and Type	Method and 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(StreamExecutionEnvironment env) Returns the default trigger associated with this WindowAssigner.
org.apache.flink.api.common.typeutils.TypeSerializer<TimeWindow>	getWindowSerializer(org.apache.flink.api.common.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> DynamicEventTimeSessionWindows<T>	withDynamicGap(SessionWindowTimeGapExtractor<T> sessionWindowTimeGapExtractor) Creates a new SessionWindows WindowAssigner that assigns elements to sessions based on the element timestamp.
static EventTimeSessionWindows	withGap(Time 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 Detail

sessionTimeout

protected long sessionTimeout

Constructor Detail

EventTimeSessionWindows

protected EventTimeSessionWindows(long sessionTimeout)

Method Detail

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(StreamExecutionEnvironment env)

Description copied from class: WindowAssigner

Returns the default trigger associated with this WindowAssigner.

Specified by:

getDefaultTrigger in class WindowAssigner<Object,TimeWindow>

toString

public String toString()

Overrides:

toString in class Object

withGap

public static EventTimeSessionWindows withGap(Time 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> DynamicEventTimeSessionWindows<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 org.apache.flink.api.common.typeutils.TypeSerializer<TimeWindow> getWindowSerializer(org.apache.flink.api.common.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.