Method checkOneLeader

src/raft/config.go:372–402

check that there's exactly one leader. try a few times in case re-elections are needed.

()

// check that there's exactly one leader.
// try a few times in case re-elections are needed.
func (cfg *config) checkOneLeader() int {
	for iters := 0; iters < 10; iters++ {
		ms := 450 + (rand.Int63() % 100)
		time.Sleep(time.Duration(ms) * time.Millisecond)

		leaders := make(map[int][]int)
		for i := 0; i < cfg.n; i++ {
			if cfg.connected[i] {
				if term, leader := cfg.rafts[i].GetState(); leader {
					leaders[term] = append(leaders[term], i)
				}
			}
		}

		lastTermWithLeader := -1
		for term, leaders := range leaders {
			if len(leaders) > 1 {
				cfg.t.Fatalf("term %d has %d (>1) leaders", term, len(leaders))
			}
			if term > lastTermWithLeader {
				lastTermWithLeader = term
			}
		}

		if len(leaders) != 0 {
			return leaders[lastTermWithLeader][0]
		}
	}
	cfg.t.Fatalf("expected one leader, got none")
	return -1
}

// check that everyone agrees on the term.
func (cfg *config) checkTerms() int {