[FLINK-8322] support getting number of existing timers in TimerService

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Not A Problem
• Affects Version/s: 1.4.0
• Component/s: API / DataStream
• Assignee: Bowen Li
• Reporter: Bowen Li
• Created: 27/Dec/17 04:43
• Updated: 02/Oct/19 17:45
• Resolved: 24/Jan/18 12:14

Description

There are pretty common use cases where users want to use timers as scheduled threads - e.g. add a timer to wake up x hours later and do something (reap old data usually) only if there's no existing timers, basically we only want at most 1 timer exists for the key all the time

Issue Links

• links to: GitHub Pull Request #5236