Method configureFSM

pkg/rules/sequence.go:230–265

configureFSM sets up the states and transitions of the state automata. A simplified representation of the constructed automata is better visualized in the diagram above +-----+ +-----+ +-----+ ----> | 0 | -----> | 1 | -----> | 2 | -----> terminal + +-----+

()

// sequence terminates. In this case, the state machine transitions to the
// expired state.
func (s *sequenceState) configureFSM() {
	for seqID, expr := range s.seq.Expressions {
		// sequence expression index is the state name
		s.exprs[seqID] = expr.Expr.String()
		// is this the last state?
		if seqID >= len(s.seq.Expressions)-1 {
			s.fsm.
				Configure(seqID).
				Permit(matchTransition, sequenceTerminalState).
				Permit(cancelTransition, sequenceDeadlineState).
				Permit(expireTransition, sequenceExpiredState)
		} else {
			// the previous state can transition to the next one
			// via the match transition, or can either go to the
			// deadline or expired states via cancel and expire
			// transitions respectively
			s.fsm.
				Configure(seqID).
				Permit(matchTransition, seqID+1).
				Permit(cancelTransition, sequenceDeadlineState).
				Permit(expireTransition, sequenceExpiredState)
		}
	}
	// configure reset transitions that are triggered
	// when the final state is reached of when a deadline
	// or sequence expiration happens
	s.fsm.
		Configure(sequenceTerminalState).
		Permit(resetTransition, sequenceInitialState)
	s.fsm.
		Configure(sequenceDeadlineState).
		Permit(resetTransition, sequenceInitialState)
	s.fsm.
		Configure(sequenceExpiredState).
		Permit(resetTransition, sequenceInitialState)
}

func (s *sequenceState) matchTransition(seqID int, e *event.Event) error {
	s.smu.Lock()