ABA problem in database area

[teymour-aldridge]

I'm mostly raising this so that people are aware that this is a risk (I know of a couple of tournaments where this has happened).

There is a classic ABA problem in the edit database area, where

A: loads list of rounds in edit-database area (state = S1)
B: edits this in the meantime (e.g. generates draw for R3) (state = S1[R3.draw = 'confirmed'])
A: updates rounds to mark round 4 as silent (state = S1 [R4 = silent])

The issue is that the behaviour people would expect is to apply the change [R4 = silent] to S3, but this is instead applied to S1 (in effect erasing the change – for example a draw and all the ballots).

[tienne-B]

You might be able to add a warning message to Edit DB or remove the option to edit from the list view, but Edit DB's behaviour cannot be altered.