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raft: add lastIndex as rejectHint

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Add the lastindex of the raft log as reject hint, so the leader can
bypass the greater index probing and decrease the next index directly
to last + 1.
This commit is contained in:
Xiang Li
2014-12-30 19:42:59 -08:00
parent 17401994c0
commit 35b907ac58
5 changed files with 83 additions and 51 deletions
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31
raft/raft.go
View File

@@ -70,13 +70,13 @@ func (pr *progress) update(n uint64) {
func (pr *progress) optimisticUpdate(n uint64) { pr.next = n + 1 }
// maybeDecrTo returns false if the given to index comes from an out of order message.
// Otherwise it decreases the progress next index and returns true.
func (pr *progress) maybeDecrTo(to uint64) bool {
// Otherwise it decreases the progress next index to min(rejected, last) and returns true.
func (pr *progress) maybeDecrTo(rejected, last uint64) bool {
pr.waitReset()
if pr.match != 0 {
// the rejection must be stale if the progress has matched and "to"
// the rejection must be stale if the progress has matched and "rejected"
// is smaller than "match".
if to <= pr.match {
if rejected <= pr.match {
return false
}
// directly decrease next to match + 1
@@ -84,12 +84,12 @@ func (pr *progress) maybeDecrTo(to uint64) bool {
return true
}
// the rejection must be stale if "to" does not match next - 1
if pr.next-1 != to {
// the rejection must be stale if "rejected" does not match next - 1
if pr.next-1 != rejected {
return false
}
if pr.next--; pr.next < 1 {
if pr.next = min(rejected, last+1); pr.next < 1 {
pr.next = 1
}
return true
@@ -245,8 +245,8 @@ func (r *raft) sendAppend(to uint64) {
if n := len(m.Entries); pr.match != 0 && n != 0 {
pr.optimisticUpdate(m.Entries[n-1].Index)
} else if pr.match == 0 {
// TODO (xiangli): better way to find out if the follwer is in good path or not
// a follower might be in bad path even if match != 0, since we optmistically
// TODO (xiangli): better way to find out if the follower is in good path or not
// a follower might be in bad path even if match != 0, since we optimistically
// increase the next.
pr.waitSet(r.heartbeatTimeout)
}
@@ -482,9 +482,10 @@ func stepLeader(r *raft, m pb.Message) {
r.bcastAppend()
case pb.MsgAppResp:
if m.Reject {
log.Printf("raft: %x received msgApp rejection from %x for index %d",
r.id, m.From, m.Index)
if r.prs[m.From].maybeDecrTo(m.Index) {
log.Printf("raft: %x received msgApp rejection(lastindex: %d) from %x for index %d",
r.id, m.RejectHint, m.From, m.Index)
if r.prs[m.From].maybeDecrTo(m.Index, m.RejectHint) {
log.Printf("raft: %x decreased progress of %x to [%s]", r.id, m.From, r.prs[m.From])
r.sendAppend(m.From)
}
} else {
@@ -572,7 +573,7 @@ func (r *raft) handleAppendEntries(m pb.Message) {
} else {
log.Printf("raft: %x [logterm: %d, index: %d] rejected msgApp [logterm: %d, index: %d] from %x",
r.id, r.raftLog.term(m.Index), m.Index, m.LogTerm, m.Index, m.From)
r.send(pb.Message{To: m.From, Type: pb.MsgAppResp, Index: m.Index, Reject: true})
r.send(pb.Message{To: m.From, Type: pb.MsgAppResp, Index: m.Index, Reject: true, RejectHint: r.raftLog.lastIndex()})
}
}
@@ -593,8 +594,8 @@ func (r *raft) handleSnapshot(m pb.Message) {
}
}
// restore recovers the statemachine from a snapshot. It restores the log and the
// configuration of statemachine.
// restore recovers the state machine from a snapshot. It restores the log and the
// configuration of state machine.
func (r *raft) restore(s pb.Snapshot) bool {
if s.Metadata.Index <= r.raftLog.committed {
return false

19
raft/raft_paper_test.go
View File

@@ -605,15 +605,16 @@ func TestFollowerCommitEntry(t *testing.T) {
func TestFollowerCheckMsgApp(t *testing.T) {
ents := []pb.Entry{{Term: 1, Index: 1}, {Term: 2, Index: 2}}
tests := []struct {
term uint64
index uint64
wreject bool
term uint64
index uint64
wreject bool
wrejectHint uint64
}{
{ents[0].Term, ents[0].Index, false},
{ents[0].Term, ents[0].Index + 1, true},
{ents[0].Term + 1, ents[0].Index, true},
{ents[1].Term, ents[1].Index, false},
{3, 3, true},
{ents[0].Term, ents[0].Index, false, 0},
{ents[0].Term, ents[0].Index + 1, true, 2},
{ents[0].Term + 1, ents[0].Index, true, 2},
{ents[1].Term, ents[1].Index, false, 0},
{3, 3, true, 2},
}
for i, tt := range tests {
storage := NewMemoryStorage()
@@ -626,7 +627,7 @@ func TestFollowerCheckMsgApp(t *testing.T) {
msgs := r.readMessages()
wmsgs := []pb.Message{
{From: 1, To: 2, Type: pb.MsgAppResp, Term: 2, Index: tt.index, Reject: tt.wreject},
{From: 1, To: 2, Type: pb.MsgAppResp, Term: 2, Index: tt.index, Reject: tt.wreject, RejectHint: tt.wrejectHint},
}
if !reflect.DeepEqual(msgs, wmsgs) {
t.Errorf("#%d: msgs = %+v, want %+v", i, msgs, wmsgs)

43
raft/raft_test.go
View File

@@ -80,50 +80,59 @@ func TestProgressUpdate(t *testing.T) {
func TestProgressMaybeDecr(t *testing.T) {
tests := []struct {
m uint64
n uint64
to uint64
m uint64
n uint64
rejected uint64
last uint64
w bool
wn uint64
}{
{
// match != 0 is always false
1, 0, 0, false, 0,
1, 0, 0, 0, false, 0,
},
{
// match != 0 and to is greater than match
// directly decrease to match+1
5, 10, 5, false, 10,
5, 10, 5, 5, false, 10,
},
{
// match != 0 and to is greater than match
// directly decrease to match+1
5, 10, 4, false, 10,
5, 10, 4, 4, false, 10,
},
{
// match != 0 and to is not greater than match
5, 10, 9, true, 6,
5, 10, 9, 9, true, 6,
},
{
// next-1 != to is always false
0, 0, 0, false, 0,
// next-1 != rejected is always false
0, 0, 0, 0, false, 0,
},
{
// next-1 != to is always false
0, 10, 5, false, 10,
// next-1 != rejected is always false
0, 10, 5, 5, false, 10,
},
{
// next>1 = decremented by 1
0, 10, 9, true, 9,
0, 10, 9, 9, true, 9,
},
{
// next>1 = decremented by 1
0, 2, 1, true, 1,
0, 2, 1, 1, true, 1,
},
{
// next<=1 = reset to 1
0, 1, 0, true, 1,
0, 1, 0, 0, true, 1,
},
{
// decrease to min(rejected, last+1)
0, 10, 9, 2, true, 3,
},
{
// rejected < 1, reset to 1
0, 10, 9, 0, true, 1,
},
}
for i, tt := range tests {
@@ -131,7 +140,7 @@ func TestProgressMaybeDecr(t *testing.T) {
match: tt.m,
next: tt.n,
}
if g := p.maybeDecrTo(tt.to); g != tt.w {
if g := p.maybeDecrTo(tt.rejected, tt.last); g != tt.w {
t.Errorf("#%d: maybeDecrTo= %t, want %t", i, g, tt.w)
}
if gm := p.match; gm != tt.m {
@@ -173,7 +182,7 @@ func TestProgressWaitReset(t *testing.T) {
p := &progress{
wait: 1,
}
p.maybeDecrTo(1)
p.maybeDecrTo(1, 1)
if p.wait != 0 {
t.Errorf("wait= %d, want 0", p.wait)
}
@@ -1001,7 +1010,7 @@ func TestLeaderAppResp(t *testing.T) {
sm.becomeCandidate()
sm.becomeLeader()
sm.readMessages()
sm.Step(pb.Message{From: 2, Type: pb.MsgAppResp, Index: tt.index, Term: sm.Term, Reject: tt.reject})
sm.Step(pb.Message{From: 2, Type: pb.MsgAppResp, Index: tt.index, Term: sm.Term, Reject: tt.reject, RejectHint: tt.index})
p := sm.prs[2]
if p.match != tt.wmatch {

20
raft/raftpb/raft.pb.go
View File

@@ -200,6 +200,7 @@ type Message struct {
Commit uint64 `protobuf:"varint,8,req,name=commit" json:"commit"`
Snapshot Snapshot `protobuf:"bytes,9,req,name=snapshot" json:"snapshot"`
Reject bool `protobuf:"varint,10,req,name=reject" json:"reject"`
RejectHint uint64 `protobuf:"varint,11,req,name=rejectHint" json:"rejectHint"`
XXX_unrecognized []byte `json:"-"`
}
@@ -725,6 +726,21 @@ func (m *Message) Unmarshal(data []byte) error {
}
}
m.Reject = bool(v != 0)
case 11:
if wireType != 0 {
return code_google_com_p_gogoprotobuf_proto.ErrWrongType
}
for shift := uint(0); ; shift += 7 {
if index >= l {
return io.ErrUnexpectedEOF
}
b := data[index]
index++
m.RejectHint |= (uint64(b) & 0x7F) << shift
if b < 0x80 {
break
}
}
default:
var sizeOfWire int
for {
@@ -1059,6 +1075,7 @@ func (m *Message) Size() (n int) {
l = m.Snapshot.Size()
n += 1 + l + sovRaft(uint64(l))
n += 2
n += 1 + sovRaft(uint64(m.RejectHint))
if m.XXX_unrecognized != nil {
n += len(m.XXX_unrecognized)
}
@@ -1278,6 +1295,9 @@ func (m *Message) MarshalTo(data []byte) (n int, err error) {
data[i] = 0
}
i++
data[i] = 0x58
i++
i = encodeVarintRaft(data, i, uint64(m.RejectHint))
if m.XXX_unrecognized != nil {
i += copy(data[i:], m.XXX_unrecognized)
}

21
raft/raftpb/raft.proto
View File

@@ -44,16 +44,17 @@ enum MessageType {
}
message Message {
required MessageType type = 1 [(gogoproto.nullable) = false];
required uint64 to = 2 [(gogoproto.nullable) = false];
required uint64 from = 3 [(gogoproto.nullable) = false];
required uint64 term = 4 [(gogoproto.nullable) = false];
required uint64 logTerm = 5 [(gogoproto.nullable) = false];
required uint64 index = 6 [(gogoproto.nullable) = false];
repeated Entry entries = 7 [(gogoproto.nullable) = false];
required uint64 commit = 8 [(gogoproto.nullable) = false];
required Snapshot snapshot = 9 [(gogoproto.nullable) = false];
required bool reject = 10 [(gogoproto.nullable) = false];
required MessageType type = 1 [(gogoproto.nullable) = false];
required uint64 to = 2 [(gogoproto.nullable) = false];
required uint64 from = 3 [(gogoproto.nullable) = false];
required uint64 term = 4 [(gogoproto.nullable) = false];
required uint64 logTerm = 5 [(gogoproto.nullable) = false];
required uint64 index = 6 [(gogoproto.nullable) = false];
repeated Entry entries = 7 [(gogoproto.nullable) = false];
required uint64 commit = 8 [(gogoproto.nullable) = false];
required Snapshot snapshot = 9 [(gogoproto.nullable) = false];
required bool reject = 10 [(gogoproto.nullable) = false];
required uint64 rejectHint = 11 [(gogoproto.nullable) = false];
}
message HardState {