func TestFollowerToCandidate(t *testing.T) {
log.SetOutput(&bytes.Buffer{})
defer log.SetOutput(os.Stdout)
oldMin, oldMax := raft.ResetElectionTimeoutMs(25, 50)
defer raft.ResetElectionTimeoutMs(oldMin, oldMax)
noop := func([]byte) ([]byte, error) { return []byte{}, nil }
server := raft.NewServer(1, &bytes.Buffer{}, noop)
server.SetPeers(raft.MakePeers(nonresponsivePeer(2), nonresponsivePeer(3)))
if server.State() != raft.Follower {
t.Fatalf("didn't start as Follower")
}
server.Start()
defer func() { server.Stop(); t.Logf("server stopped") }()
time.Sleep(raft.MaximumElectionTimeout())
cutoff := time.Now().Add(2 * raft.MinimumElectionTimeout())
backoff := raft.BroadcastInterval()
for {
if time.Now().After(cutoff) {
t.Fatal("failed to become Candidate")
}
if state := server.State(); state != raft.Candidate {
time.Sleep(backoff)
backoff *= 2
continue
}
t.Logf("became Candidate")
break
}
}
func TestSimpleConsensus(t *testing.T) {
logBuffer := &bytes.Buffer{}
log.SetOutput(logBuffer)
defer log.SetOutput(os.Stdout)
defer printOnFailure(t, logBuffer)
oldMin, oldMax := raft.ResetElectionTimeoutMs(25, 50)
defer raft.ResetElectionTimeoutMs(oldMin, oldMax)
type SetValue struct {
Value int32 `json:"value"`
}
var i1, i2, i3 int32
applyValue := func(id uint64, i *int32) func([]byte) ([]byte, error) {
return func(cmd []byte) ([]byte, error) {
var sv SetValue
if err := json.Unmarshal(cmd, &sv); err != nil {
return []byte{}, err
}
atomic.StoreInt32(i, sv.Value)
return json.Marshal(map[string]interface{}{"applied_to_server": id, "applied_value": sv.Value})
}
}
s1 := raft.NewServer(1, &bytes.Buffer{}, applyValue(1, &i1))
s2 := raft.NewServer(2, &bytes.Buffer{}, applyValue(2, &i2))
s3 := raft.NewServer(3, &bytes.Buffer{}, applyValue(3, &i3))
s1Responses := &synchronizedBuffer{}
s2Responses := &synchronizedBuffer{}
s3Responses := &synchronizedBuffer{}
defer func(sb *synchronizedBuffer) { t.Logf("s1 responses: %s", sb.String()) }(s1Responses)
defer func(sb *synchronizedBuffer) { t.Logf("s2 responses: %s", sb.String()) }(s2Responses)
defer func(sb *synchronizedBuffer) { t.Logf("s3 responses: %s", sb.String()) }(s3Responses)
peers := raft.MakePeers(
raft.NewLocalPeer(s1),
raft.NewLocalPeer(s2),
raft.NewLocalPeer(s3),
)
s1.SetPeers(peers)
s2.SetPeers(peers)
s3.SetPeers(peers)
s1.Start()
s2.Start()
s3.Start()
defer s1.Stop()
defer s2.Stop()
defer s3.Stop()
var v int32 = 42
cmd, _ := json.Marshal(SetValue{v})
response := make(chan []byte, 1)
func() {
for {
switch err := s1.Command(cmd, response); err {
case nil:
return
case raft.ErrUnknownLeader:
time.Sleep(raft.MinimumElectionTimeout())
default:
t.Fatal(err)
}
}
}()
r, ok := <-response
if ok {
s1Responses.Write(r)
} else {
t.Logf("didn't receive command response")
}
ticker := time.Tick(raft.BroadcastInterval())
timeout := time.After(1 * time.Second)
for {
select {
case <-ticker:
i1l := atomic.LoadInt32(&i1)
i2l := atomic.LoadInt32(&i2)
i3l := atomic.LoadInt32(&i3)
t.Logf("i1=%02d i2=%02d i3=%02d", i1l, i2l, i3l)
if i1l == v && i2l == v && i3l == v {
t.Logf("success!")
return
}
case <-timeout:
t.Fatal("timeout")
}
}
}