It will cause a deadlock when call breaker.Counts() method in the OnStateChange() method

[Brandon-zhong]

When the OnStateChange method is trigered, I want to know the breaker counts, so i call breaker.Counts(), but I get a deadlock
The code is :

OnStateChange: func(name string, from gobreaker.State, to gobreaker.State) {
	// NOTICE：do not call breaker.Counts() in this method , it will cause a deadlock !!! 
	counts := breaker.Counts()
	logger.Infof("key: %s, breaker state has change, from %s to %s , the data --> %v", breaker.Name(), from.String(), to.String(), counts)
}

What method should I call when I want to know the counts number in OnStateChange method ?

[Jurperle]

1.creating a goroutine where a channel receive change and call breaker.Counts().
2.breaker.Counts() function removes lock. Count is just a copy.

[YoshiyukiMineo]

1.creating a goroutine where a channel receive change and call breaker.Counts().

I think the above way is better:

	type StateChange struct {
		Name   string
		From   gobreaker.State
		To     gobreaker.State
		Counts gobreaker.Counts
	}
	ch := make(chan *StateChange)
	
	var cb *gobreaker.CircuitBreaker
	st := gobreaker.Settings{
		OnStateChange: func(name string, from gobreaker.State, to gobreaker.State) {
			go func(name string, from gobreaker.State, to gobreaker.State) {
				ch <- &StateChange{
					Name:   name,
					From:   from,
					To:     to,
					Counts: cb.Counts(),
				}
			}(name, from, to)
		},
	}
	cb = gobreaker.NewCircuitBreaker(st)

[Jurperle]

#40
This request can resolve the problem. Async OnStateChange function.