Hi, I am implementing a merge-able trigger, and having a problem in clearing the registered timers for a merged window (a window has been merged into the merging result). For my implementation, the trigger registers multiple timers for each element at Trigger#onElement(). State is used to keep track of the registered event time, so that timer can be removed at Trigger#clear() later.
However, clearing the registered timers in this way doesn't work if the window has been merged. The state of origin window is removed during merging. Method AbstractHeapMergingState#mergeNamespaces() removes the state of merged window. I think the ContinuousEventTimeTrigger shipped with flink would have same issue. My question is is there a way to keep the state for a merged window? One way I can think of is to implement a custom heap state that add the state back in AbstractHeapMergingState#mergeState() method. Or is there a way to clear the timers without using state? Can I twist the internal timer's source code to expose a method to remove all timers for a specified window? Please advise and thank you for your help. Best Yan
