when I use SetState in a callback in a `before_<event>` => deadlock

[lzecca78]

I am writing an fsm that needs the follow:

an Event named creating can goes to 3 different states (ok, unreachable, creating) depending on some checks. In order to realize this, I wrote a callback function like this one:

func (p *ClusterState) beforeCreating(e *fsm.Event) {
	p.Logger.Infof("Triggered event %v, trying to reach status %s", e.Event, e.Dst)

	if p.Unreachable {
		timeLimit := p.CreatedAt.Add(time.Minute * 30)
		if timeLimit.Before(p.Clock.Now()) {
			e.FSM.SetState("CREATING") // it hangs here
		}
	}
}

Probably there is a better way to do that, or i am missing something.
Can anyone help me with that?
Thanks in advance!

[lzecca78]

The same happens if I try to trigger an FSM.Event instead of SetState

[itsprdp]

This is a known issue and @annismckenzie has put together a nice PR #82 which is yet to be merged.

Hackish solution that might work for you:

func (p *ClusterState) unreachableLogic() {
  timeLimit := p.CreatedAt.Add(time.Minute * 30)
  if timeLimit.Before(p.Clock.Now()) {
    e.FSM.SetState("CREATING") // it hangs here
  }

}

func (p *ClusterState) beforeCreating(e *fsm.Event) {
  p.Logger.Infof("Triggered event %v, trying to reach status %s", e.Event, e.Dst)

  if p.Unreachable {
    go p.unreachableLogic()
  }
}

[lzecca78]

thanks for your help @itsprdp, I ended up with a solution that uses heavily the Metadata and GetMetadata feature and then a big switch case for a call to a transition to the desired state. Is of course sub-optimal, but unless the branch will not be merged, it is working. After the fix, I will revisit it. Thanks again for your help, really appreciated it!

[annismckenzie]

#88 was merged today and you may want to revisit this. 🙃