Package org.apache.beam.sdk.transforms.windowing

Class SlidingWindows

java.lang.Object

org.apache.beam.sdk.transforms.windowing.WindowFn<Object,IntervalWindow>

org.apache.beam.sdk.transforms.windowing.NonMergingWindowFn<Object,IntervalWindow>

org.apache.beam.sdk.transforms.windowing.SlidingWindows

All Implemented Interfaces:

Serializable, HasDisplayData

public class SlidingWindows
extends NonMergingWindowFn<Object,IntervalWindow>

A WindowFn that windows values into possibly overlapping fixed-size timestamp-based windows.

For example, in order to window data into 10 minute windows that update every minute:

 PCollection<Integer> items = ...;
 PCollection<Integer> windowedItems = items.apply(
   Window.<Integer>into(SlidingWindows.of(Duration.standardMinutes(10))));
 

See Also:

• Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.beam.sdk.transforms.windowing.WindowFn

WindowFn.AssignContext, WindowFn.MergeContext

Method Summary

Modifier and Type	Method	Description
boolean	assignsToOneWindow()	Returns true if this WindowFn always assigns an element to exactly one window.
Collection<IntervalWindow>	assignWindows(WindowFn<Object,IntervalWindow>.AssignContext c)	Given a timestamp and element, returns the set of windows into which it should be placed.
Collection<IntervalWindow>	assignWindows(Instant timestamp)
boolean	equals(@Nullable Object object)
SlidingWindows	every(Duration period)	Returns a new SlidingWindows with the original size, that assigns timestamps into half-open intervals of the form [N * period, N * period + size), where 0 is the epoch.
WindowMappingFn<IntervalWindow>	getDefaultWindowMappingFn()	Return a WindowMappingFn that returns the earliest window that contains the end of the main-input window.
Duration	getOffset()
Duration	getPeriod()
Duration	getSize()
int	hashCode()
boolean	isCompatible(WindowFn<?,?> other)	Returns whether this performs the same merging as the given WindowFn.
static SlidingWindows	of(Duration size)	Assigns timestamps into half-open intervals of the form [N * period, N * period + size), where 0 is the epoch.
void	populateDisplayData(DisplayData.Builder builder)	Register display data for the given transform or component.
void	verifyCompatibility(WindowFn<?,?> other)	Throw IncompatibleWindowException if this WindowFn does not perform the same merging as the given $WindowFn.
Coder<IntervalWindow>	windowCoder()	Returns the Coder used for serializing the windows used by this windowFn.
SlidingWindows	withOffset(Duration offset)	Assigns timestamps into half-open intervals of the form [N * period + offset, N * period + offset + size).

Methods inherited from class org.apache.beam.sdk.transforms.windowing.NonMergingWindowFn

isNonMerging, mergeWindows

Methods inherited from class org.apache.beam.sdk.transforms.windowing.WindowFn

getWindowTypeDescriptor

Methods inherited from class java.lang.Object

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

Method Details

of

public static SlidingWindows of(Duration size)

Assigns timestamps into half-open intervals of the form [N * period, N * period + size), where 0 is the epoch.

If every(org.joda.time.Duration) is not called, the period defaults to the largest time unit smaller than the given duration. For example, specifying a size of 5 seconds will result in a default period of 1 second.

every

public SlidingWindows every(Duration period)

Returns a new SlidingWindows with the original size, that assigns timestamps into half-open intervals of the form [N * period, N * period + size), where 0 is the epoch.

withOffset

public SlidingWindows withOffset(Duration offset)

Assigns timestamps into half-open intervals of the form [N * period + offset, N * period + offset + size).

Throws:

IllegalArgumentException - if offset is not in [0, period)

windowCoder

public Coder<IntervalWindow> windowCoder()

Description copied from class: WindowFn

Returns the Coder used for serializing the windows used by this windowFn.

Specified by:

windowCoder in class WindowFn<Object,IntervalWindow>

assignWindows

public Collection<IntervalWindow> assignWindows(WindowFn<Object,IntervalWindow>.AssignContext c)

Description copied from class: WindowFn

Given a timestamp and element, returns the set of windows into which it should be placed.

Specified by:

assignWindows in class WindowFn<Object,IntervalWindow>

assignWindows

public Collection<IntervalWindow> assignWindows(Instant timestamp)

getDefaultWindowMappingFn

public WindowMappingFn<IntervalWindow> getDefaultWindowMappingFn()

Return a WindowMappingFn that returns the earliest window that contains the end of the main-input window.

Specified by:

getDefaultWindowMappingFn in class WindowFn<Object,IntervalWindow>

isCompatible

public boolean isCompatible(WindowFn<?,?> other)

Description copied from class: WindowFn

Returns whether this performs the same merging as the given WindowFn.

Specified by:

isCompatible in class WindowFn<Object,IntervalWindow>

assignsToOneWindow

public boolean assignsToOneWindow()

Description copied from class: WindowFn

Returns true if this WindowFn always assigns an element to exactly one window.

If this varies per-element, or cannot be determined, conservatively return false.

By default, returns false.

Overrides:

assignsToOneWindow in class WindowFn<Object,IntervalWindow>

verifyCompatibility

public void verifyCompatibility(WindowFn<?,?> other)
                         throws IncompatibleWindowException

Description copied from class: WindowFn

Throw IncompatibleWindowException if this WindowFn does not perform the same merging as the given $WindowFn.

Overrides:

verifyCompatibility in class WindowFn<Object,IntervalWindow>

Throws:

IncompatibleWindowException - if compared WindowFns are not compatible.

populateDisplayData

public void populateDisplayData(DisplayData.Builder builder)

Description copied from class: WindowFn

Register display data for the given transform or component.

populateDisplayData(DisplayData.Builder) is invoked by Pipeline runners to collect display data via DisplayData.from(HasDisplayData). Implementations may call super.populateDisplayData(builder) in order to register display data in the current namespace, but should otherwise use subcomponent.populateDisplayData(builder) to use the namespace of the subcomponent.

By default, does not register any display data. Implementors may override this method to provide their own display data.

Specified by:

populateDisplayData in interface HasDisplayData

Overrides:

populateDisplayData in class WindowFn<Object,IntervalWindow>

Parameters:

builder - The builder to populate with display data.

See Also:

• HasDisplayData

getPeriod

public Duration getPeriod()

getSize

public Duration getSize()

getOffset

public Duration getOffset()

equals

public boolean equals(@Nullable Object object)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object