Golang finite-state machine.
In this example we do the following:
- utilize a back-reference to our state maching using
MachineProvider; - use
Expiringstate handler to timeout a state; - create custom state handlers that print the states and terminate the app;
- join the handlers using
Compose.
In this example we start with stInit, and then send evInitialized, which
switches the state into stFinal.
const (
stInit fsm.StateType = "stInit"
stFinal fsm.StateType = "stFinal"
evInitialized fsm.EventType = "evInitialized"
)
transitions := fsm.Transitions{
fsm.When(stInit, evInitialized): stFinal,
}
fsm := fsm.New(stInit, transitions, nil, nil)
fsm.Send(evInitialized)In this example we use an Expiring state handler, which sends events to the
FSM with a delay. Since timer events are asynchronous, we recommend to use the
asynchronous FSM implementation.
const (
stInit StateType = "stInit"
stWaitTimeout StateType = "stWaitTimeout"
stFinal StateType = "stFinal"
evInitialized EventType = "evInitialized"
evTimeout EventType = "evTimeout"
)
transitions := Transitions{
When(stInit, evInitialized): stWaitTimeout,
When(stWaitTimeout, evTimeout): stFinal,
}
provider := new(MachineProvider)
states := States{
stWaitTimeout: NewExpiring(provider, After(time.Second), evTimeout),
}
fsm := fsm.NewAsync(stInit, transitions, states, nil)
provider.Set(fsm)
fsm.Send(evInitialized)
fsm.Run()