GetSync method #16
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GetSync method #16
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Add a method that will insure our events are processed before we return a state value
ingar
approved these changes
Jul 13, 2020
fsm/fsm_group.go
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| err := s.SendSync(ctx, id, nilEvent{}) | ||
| if err != nil { | ||
| return err | ||
| } | ||
| return s.Get(id).Get(out) |
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Was wondering if there was a chance for a race here? I'm not sure how GetSync gets called in the loop; is it possible that more events have come in after the nilEvent, between the SendSync and Get calls? Not sure that it matters for our use case.
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yes, it is technically possible. I'm not concerned. The main concern is anything that happened before GetSync was called is processed. That's the guarantee GetSync offers.
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Goals
Often we want to dispatch events and then read the result. However, currently, Get reads from the datastore immediately, while the events may still not have been processed in thread. GetSync allows you to get the value with a guarantee that any events you've already dispatched will be processed before your value is read.
Implementation