Package 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:
Serializable
public abstract class WindowMappingFn<TargetWindowT extends BoundedWindow> extends Object implements Serializable
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:

  • Constructor Details

    • 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 Details

    • 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.