org.apache.beam.sdk.transforms.windowing

Class WindowMappingFn<TargetWindowT extends BoundedWindow>

java.lang.Object

org.apache.beam.sdk.transforms.windowing.WindowMappingFn<TargetWindowT>

All Implemented Interfaces:

java.io.Serializable

@Experimental
public abstract class WindowMappingFn<TargetWindowT extends BoundedWindow>
extends java.lang.Object
implements java.io.Serializable

Experimental! This will be ready for users eventually, but should be considered internal for now. No backwards compatibility guarantees.

A function that takes the windows of elements in a main input and maps them to the appropriate window in a PCollectionView consumed as a side input.

See Also:

Serialized Form

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	WindowMappingFn() Create a new WindowMappingFn with zero maximum lookback.
protected	WindowMappingFn(Duration maximumLookback) Create a new WindowMappingFn with the specified maximum lookback.

Method Summary

Modifier and Type	Method and Description
abstract TargetWindowT	getSideInputWindow(BoundedWindow mainWindow) Returns the window of the side input corresponding to the given window of the main input.
Duration	maximumLookback() The maximum distance between the end of any main input window mainWindow and the end of the side input window returned by getSideInputWindow(BoundedWindow)

Methods inherited from class java.lang.Object

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

Constructor Detail

WindowMappingFn

protected WindowMappingFn()

Create a new WindowMappingFn with zero maximum lookback.

WindowMappingFn

protected WindowMappingFn(Duration maximumLookback)

Create a new WindowMappingFn with the specified maximum lookback.

Method Detail

getSideInputWindow

public abstract TargetWindowT getSideInputWindow(BoundedWindow mainWindow)

Returns the window of the side input corresponding to the given window of the main input.

maximumLookback

public final Duration maximumLookback()

The maximum distance between the end of any main input window mainWindow and the end of the side input window returned by getSideInputWindow(BoundedWindow)

A side input window w becomes unreachable when the input watermarks for all consumers surpasses the timestamp:

(end of side input window) + (maximum lookback) + (main input allowed lateness).

At this point, every main input window that could map to w is expired.