raft: change ins from array to map

raft/node.go

@@ -17,13 +17,13 @@ type Node struct {
 	sm      *stateMachine
 }
 
-func New(k, addr int, heartbeat, election tick) *Node {
+func New(addr int, peer []int, heartbeat, election tick) *Node {
 	if election < heartbeat*3 {
 		panic("election is least three times as heartbeat [election: %d, heartbeat: %d]")
 	}
 
 	n := &Node{
-		sm:        newStateMachine(k, addr),
+		sm:        newStateMachine(addr, peer),
 		heartbeat: heartbeat,
 		election:  election,
 	}

raft/node_test.go

@@ -10,7 +10,7 @@ const (
 )
 
 func TestTickMsgHub(t *testing.T) {
-	n := New(3, 0, defaultHeartbeat, defaultElection)
+	n := New(0, []int{0, 1, 2}, defaultHeartbeat, defaultElection)
 
 	for i := 0; i < defaultElection+1; i++ {
 		n.Tick()
@@ -30,7 +30,7 @@ func TestTickMsgHub(t *testing.T) {
 
 func TestTickMsgBeat(t *testing.T) {
 	k := 3
-	n := New(k, 0, defaultHeartbeat, defaultElection)
+	n := New(0, []int{0, 1, 2}, defaultHeartbeat, defaultElection)
 
 	n.Step(Message{Type: msgHup}) // become leader please
 	for _, m := range n.Msgs() {
@@ -70,7 +70,7 @@ func TestResetElapse(t *testing.T) {
 	}
 
 	for i, tt := range tests {
-		n := New(3, 1, defaultHeartbeat, defaultElection)
+		n := New(0, []int{0, 1, 2}, defaultHeartbeat, defaultElection)
 		n.sm.term = 2
 
 		n.Tick()

raft/raft.go

@@ -82,10 +82,6 @@ func (in *index) decr() {
 }
 
 type stateMachine struct {
-	// k is the number of peers
-	k int
-
-	// addr is an integer representation of our address amoungst our peers. It is 0 <= addr < k.
 	addr int
 
 	// the term we are participating in at any time
@@ -97,7 +93,7 @@ type stateMachine struct {
 	// the log
 	log *log
 
-	ins []index
+	ins map[int]*index
 
 	state stateType
 
@@ -109,8 +105,11 @@ type stateMachine struct {
 	lead int
 }
 
-func newStateMachine(k, addr int) *stateMachine {
-	sm := &stateMachine{k: k, addr: addr, log: newLog()}
+func newStateMachine(addr int, peer []int) *stateMachine {
+	sm := &stateMachine{addr: addr, log: newLog(), ins: make(map[int]*index)}
+	for p := range peer {
+		sm.ins[p] = &index{}
+	}
 	sm.reset()
 	return sm
 }
@@ -156,7 +155,7 @@ func (sm *stateMachine) sendAppend(to int) {
 
 // bcastAppend sends RRPC, with entries to all peers that are not up-to-date according to sm.mis.
 func (sm *stateMachine) bcastAppend() {
-	for i := 0; i < sm.k; i++ {
+	for i := range sm.ins {
 		if i == sm.addr {
 			continue
 		}
@@ -185,9 +184,8 @@ func (sm *stateMachine) reset() {
 	sm.lead = none
 	sm.vote = none
 	sm.votes = make(map[int]bool)
-	sm.ins = make([]index, sm.k)
 	for i := range sm.ins {
-		sm.ins[i] = index{next: sm.log.lastIndex() + 1}
+		sm.ins[i] = &index{next: sm.log.lastIndex() + 1}
 		if i == sm.addr {
 			sm.ins[i].match = sm.log.lastIndex()
 		}
@@ -195,7 +193,7 @@ func (sm *stateMachine) reset() {
 }
 
 func (sm *stateMachine) q() int {
-	return sm.k/2 + 1
+	return len(sm.ins)/2 + 1
 }
 
 func (sm *stateMachine) becomeFollower(term, lead int) {
@@ -241,7 +239,7 @@ func (sm *stateMachine) Step(m Message) {
 			sm.becomeLeader()
 			return
 		}
-		for i := 0; i < sm.k; i++ {
+		for i := range sm.ins {
 			if i == sm.addr {
 				continue
 			}

raft/raft_test.go

@@ -142,8 +142,8 @@ func TestCannotCommitWithoutNewTermEntry(t *testing.T) {
 }
 
 func TestDuelingCandidates(t *testing.T) {
-	a := newStateMachine(0, 0) // k, addr are set later
-	c := newStateMachine(0, 0)
+	a := newStateMachine(0, nil) // k, addr are set later
+	c := newStateMachine(0, nil)
 
 	tt := newNetwork(a, nil, c)
 	tt.cut(0, 2)
@@ -370,11 +370,11 @@ func TestCommit(t *testing.T) {
 	}
 
 	for i, tt := range tests {
-		ins := make([]index, len(tt.matches))
-		for j := 0; j < len(ins); j++ {
-			ins[j] = index{tt.matches[j], tt.matches[j] + 1}
+		ins := make(map[int]*index)
+		for j := 0; j < len(tt.matches); j++ {
+			ins[j] = &index{tt.matches[j], tt.matches[j] + 1}
 		}
-		sm := &stateMachine{log: &log{ents: tt.logs}, ins: ins, k: len(ins), term: tt.smTerm}
+		sm := &stateMachine{log: &log{ents: tt.logs}, ins: ins, term: tt.smTerm}
 		sm.maybeCommit()
 		if g := sm.log.committed; g != tt.w {
 			t.Errorf("#%d: committed = %d, want %d", i, g, tt.w)
@@ -469,7 +469,7 @@ func TestStateTransition(t *testing.T) {
 				}
 			}()
 
-			sm := newStateMachine(1, 0)
+			sm := newStateMachine(0, []int{0})
 			sm.state = tt.from
 
 			switch tt.to {
@@ -504,7 +504,7 @@ func TestAllServerStepdown(t *testing.T) {
 	tterm := 3
 
 	for i, tt := range tests {
-		sm := newStateMachine(3, 0)
+		sm := newStateMachine(0, []int{0, 1, 2})
 		switch tt {
 		case stateFollower:
 			sm.becomeFollower(1, 0)
@@ -545,7 +545,8 @@ func TestLeaderAppResp(t *testing.T) {
 	for i, tt := range tests {
 		// sm term is 1 after it becomes the leader.
 		// thus the last log term must be 1 to be committed.
-		sm := &stateMachine{addr: 0, k: 3, log: &log{ents: []Entry{{}, {Term: 0}, {Term: 1}}}}
+		sm := newStateMachine(0, []int{0, 1, 2})
+		sm.log = &log{ents: []Entry{{}, {Term: 0}, {Term: 1}}}
 		sm.becomeCandidate()
 		sm.becomeLeader()
 		sm.Step(Message{From: 1, Type: msgAppResp, Index: tt.index, Term: sm.term})
@@ -578,7 +579,7 @@ func TestRecvMsgBeat(t *testing.T) {
 	}
 
 	for i, tt := range tests {
-		sm := newStateMachine(3, 0)
+		sm := newStateMachine(0, []int{0, 1, 2})
 		sm.log = &log{ents: []Entry{{}, {Term: 0}, {Term: 1}}}
 		sm.term = 1
 		sm.state = tt.state
@@ -615,14 +616,23 @@ type network struct {
 // newNetwork initializes a network from peers. A nil node will be replaced
 // with a new *stateMachine. A *stateMachine will get its k, addr.
 func newNetwork(peers ...Interface) *network {
+	peerAddrs := make([]int, len(peers))
+	for i := range peers {
+		peerAddrs[i] = i
+	}
+
 	for addr, p := range peers {
 		switch v := p.(type) {
 		case nil:
-			sm := newStateMachine(len(peers), addr)
+			sm := newStateMachine(addr, peerAddrs)
 			peers[addr] = sm
 		case *stateMachine:
-			v.k = len(peers)
 			v.addr = addr
+			v.ins = make(map[int]*index)
+			for i := range peerAddrs {
+				v.ins[i] = &index{}
+			}
+			v.reset()
 		}
 	}
 	return &network{peers: peers, dropm: make(map[connem]float64)}