[BEAM-1591] Implement Combine optimizations for GABW in streaming

• Type: Improvement
• Status: Open
• Priority: P3
• Resolution: Unresolved
• Component/s: runner-spark
• Assignee: Unassigned
• Reporter: Amit Sela
• Created: 02/Mar/17 13:48
• Updated: 03/Jun/22 16:23

Description

This should be straight-forward.
Introduce AccumT generics in SparkGroupAlsoByWindowViaWindowSet and call with InputT for GBK and AccumT with Combine.
Pass the proper SystemReduceFn instead of creating it in SparkGroupAlsoByWindowViaWindowSet.
For combine, extract the output from the fired accumulated output.