[FLINK-3714] Add Support for "Allowed Lateness"

• Type: Sub-task
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.1.0
• Component/s: API / DataStream
• Assignee: Kostas Kloudas
• Reporter: Aljoscha Krettek
• Created: 07/Apr/16 12:16
• Updated: 28/Feb/19 11:14
• Resolved: 29/Jul/16 08:37

Description

As mentioned in https://docs.google.com/document/d/1Xp-YBf87vLTduYSivgqWVEMjYUmkA-hyb4muX3KRl08/edit# we should add support for an allowed lateness setting.

This includes several things:

• API for setting allowed lateness
• Dropping of late elements
• Garbage collection of windows state/timers

Depending on whether the WindowAssigner assigns windows based on event time or processing time we have to adjust the GC behavior. For event-time windows "allowed lateness" makes sense and we should garbage collect after this expires. For processing-time windows "allowed lateness" does not make sense and we should always GC window state/timers at the end timestamp of a processing-time window. I think that we need a method for this on WindowAssigner that allows to differentiate between event-time windows and processing-time windows: boolean WindowAssigner.isEventTime().

Issue Links

• is depended upon by: FLINK-3715 Move Accumulating/Discarding from Trigger to WindowOperator
• links to: GitHub Pull Request #2093