CheckVariable / CheckEvent FSM transition race condition

[zsoikParticipant]

I could produce a FSM transition race condition by using the following condition:

(All true)
– A blackboard variable X is NULL
– An event occurs, saving the parameter in the blackboard as X

The transition never triggers because:

– Frame the event occurs: Variable is null (Success!) and CheckEvent<T> stores variable in BB (Fail!) -> Fail
– Frame after event occurs: Variable is not null (Fail!) and CheckEvent<T> yields (Success!) -> Fail

[attachment file=”11-39-08–002070.png”]

NC 2.6.4 / Unity 5.5.0p3

[zsoikParticipant]

Can be worked around by using a temporary blackboard variable and a second state that copies the temp to the actual variable:

[attachment file=”11-46-12–002071.png”]

[GavalakisKeymaster]

Hey,
That is a very special case scenario here, since the value that the event checked is setting, is also the value that is checked itself.
It is interesting problem though. I will have to take a better look at how it could be solved if required. Definitely not an easy one 🙂

[Author]

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