Method initFSM

pkg/rules/sequence.go:166–199

initFSM initializes the state machine and installs transition callbacks that are triggered when the expression in the sequence matches, it expires or the deadline occurs.

()

// that are triggered when the expression in the sequence matches, it expires
// or the deadline occurs.
func (s *sequenceState) initFSM() {
	s.fsm = fsm.NewStateMachine(s.initialState)
	s.fsm.OnTransitioned(func(ctx context.Context, transition fsm.Transition) {
		// schedule span deadline for the current state unless initial/meta states
		if s.maxSpan != 0 && s.isStateSchedulable(s.currentState()) {
			log.Debugf("scheduling max span deadline of %v for expression [%s] of sequence [%s]", s.maxSpan, s.expr(s.currentState()), s.name)
			s.scheduleMaxSpanDeadline(s.currentState(), s.maxSpan)
		}
		// if the sequence was deadlined/expired, we can disable the deadline
		// status when the first expression in the sequence is reevaluated
		if transition.Source == s.initialState && s.inDeadline.Load() {
			s.inDeadline.Store(false)
		}
		if transition.Source == s.initialState && s.inExpired.Load() {
			s.inExpired.Store(false)
		}
		// clear state in case of expire/deadline transitions
		if transition.Trigger == expireTransition || transition.Trigger == cancelTransition {
			s.clear()
		}
		if transition.Trigger == matchTransition {
			log.Debugf("state trigger from expression [%s] of sequence [%s]", s.expr(transition.Source), s.name)
			// a match occurred from current to next state.
			// Stop deadline execution for the old current state
			if span, ok := s.spanDeadlines[transition.Source]; ok {
				log.Debugf("stopped max span deadline for expression [%s] of sequence [%s]", s.expr(transition.Source), s.name)
				span.Stop()
				delete(s.spanDeadlines, transition.Source)
			}
			// save expression match
			s.states[transition.Source] = true
		}
	})
}

// configureFSM sets up the states and transitions of the state automata.
// A simplified representation of the constructed automata is better