Merge pull request #1889 from xiang90/chord_raft

Chord raft

raft/raft.go

@@ -56,9 +56,7 @@ func (st StateType) MarshalJSON() ([]byte, error) {
 	return []byte(fmt.Sprintf("%q", st.String())), nil
 }
 
-type progress struct {
-	match, next uint64
-}
+type progress struct{ match, next uint64 }
 
 func (pr *progress) update(n uint64) {
 	if pr.match < n {
@@ -69,9 +67,7 @@ func (pr *progress) update(n uint64) {
 	}
 }
 
-func (pr *progress) optimisticUpdate(n uint64) {
-	pr.next = n + 1
-}
+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.
@@ -183,34 +179,15 @@ func (r *raft) softState() *SoftState {
 	return &SoftState{Lead: r.lead, RaftState: r.state, Nodes: r.nodes()}
 }
 
-func (r *raft) String() string {
-	s := fmt.Sprintf(`state=%v term=%d`, r.state, r.Term)
-	switch r.state {
-	case StateFollower:
-		s += fmt.Sprintf(" vote=%v lead=%v", r.Vote, r.lead)
-	case StateCandidate:
-		s += fmt.Sprintf(` votes="%v"`, r.votes)
-	case StateLeader:
-		s += fmt.Sprintf(` prs="%v"`, r.prs)
-	}
-	return s
-}
+func (r *raft) q() int { return len(r.prs)/2 + 1 }
 
-func (r *raft) poll(id uint64, v bool) (granted int) {
-	if v {
-		log.Printf("raft: %x received vote from %x at term %d", r.id, id, r.Term)
-	} else {
-		log.Printf("raft: %x received vote rejection from %x at term %d", r.id, id, r.Term)
-	}
-	if _, ok := r.votes[id]; !ok {
-		r.votes[id] = v
-	}
-	for _, vv := range r.votes {
-		if vv {
-			granted++
-		}
+func (r *raft) nodes() []uint64 {
+	nodes := make([]uint64, 0, len(r.prs))
+	for k := range r.prs {
+		nodes = append(nodes, k)
 	}
-	return granted
+	sort.Sort(uint64Slice(nodes))
+	return nodes
 }
 
 // send persists state to stable storage and then sends to its mailbox.
@@ -323,10 +300,6 @@ func (r *raft) reset(term uint64) {
 	r.pendingConf = false
 }
 
-func (r *raft) q() int {
-	return len(r.prs)/2 + 1
-}
-
 func (r *raft) appendEntry(e pb.Entry) {
 	e.Term = r.Term
 	e.Index = r.raftLog.lastIndex() + 1
@@ -418,6 +391,23 @@ func (r *raft) campaign() {
 	}
 }
 
+func (r *raft) poll(id uint64, v bool) (granted int) {
+	if v {
+		log.Printf("raft: %x received vote from %x at term %d", r.id, id, r.Term)
+	} else {
+		log.Printf("raft: %x received vote rejection from %x at term %d", r.id, id, r.Term)
+	}
+	if _, ok := r.votes[id]; !ok {
+		r.votes[id] = v
+	}
+	for _, vv := range r.votes {
+		if vv {
+			granted++
+		}
+	}
+	return granted
+}
+
 func (r *raft) Step(m pb.Message) error {
 	// TODO(bmizerany): this likely allocs - prevent that.
 	defer func() { r.Commit = r.raftLog.committed }()
@@ -449,51 +439,6 @@ func (r *raft) Step(m pb.Message) error {
 	return nil
 }
 
-func (r *raft) handleAppendEntries(m pb.Message) {
-	if mlastIndex, ok := r.raftLog.maybeAppend(m.Index, m.LogTerm, m.Commit, m.Entries...); ok {
-		r.send(pb.Message{To: m.From, Type: pb.MsgAppResp, Index: mlastIndex})
-	} 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})
-	}
-}
-
-func (r *raft) handleHeartbeat(m pb.Message) {
-	r.raftLog.commitTo(m.Commit)
-}
-
-func (r *raft) handleSnapshot(m pb.Message) {
-	sindex, sterm := m.Snapshot.Metadata.Index, m.Snapshot.Metadata.Term
-	if r.restore(m.Snapshot) {
-		log.Printf("raft: %x [commit: %d] restored snapshot [index: %d, term: %d]",
-			r.id, r.Commit, sindex, sterm)
-		r.send(pb.Message{To: m.From, Type: pb.MsgAppResp, Index: r.raftLog.lastIndex()})
-	} else {
-		log.Printf("raft: %x [commit: %d] ignored snapshot [index: %d, term: %d]",
-			r.id, r.Commit, sindex, sterm)
-		r.send(pb.Message{To: m.From, Type: pb.MsgAppResp, Index: r.raftLog.committed})
-	}
-}
-
-func (r *raft) resetPendingConf() { r.pendingConf = false }
-
-func (r *raft) addNode(id uint64) {
-	if _, ok := r.prs[id]; ok {
-		// Ignore any redundant addNode calls (which can happen because the
-		// initial bootstrapping entries are applied twice).
-		return
-	}
-
-	r.setProgress(id, 0, r.raftLog.lastIndex()+1)
-	r.pendingConf = false
-}
-
-func (r *raft) removeNode(id uint64) {
-	r.delProgress(id)
-	r.pendingConf = false
-}
-
 type stepFunc func(r *raft, m pb.Message)
 
 func stepLeader(r *raft, m pb.Message) {
@@ -597,6 +542,33 @@ func stepFollower(r *raft, m pb.Message) {
 	}
 }
 
+func (r *raft) handleAppendEntries(m pb.Message) {
+	if mlastIndex, ok := r.raftLog.maybeAppend(m.Index, m.LogTerm, m.Commit, m.Entries...); ok {
+		r.send(pb.Message{To: m.From, Type: pb.MsgAppResp, Index: mlastIndex})
+	} 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})
+	}
+}
+
+func (r *raft) handleHeartbeat(m pb.Message) {
+	r.raftLog.commitTo(m.Commit)
+}
+
+func (r *raft) handleSnapshot(m pb.Message) {
+	sindex, sterm := m.Snapshot.Metadata.Index, m.Snapshot.Metadata.Term
+	if r.restore(m.Snapshot) {
+		log.Printf("raft: %x [commit: %d] restored snapshot [index: %d, term: %d]",
+			r.id, r.Commit, sindex, sterm)
+		r.send(pb.Message{To: m.From, Type: pb.MsgAppResp, Index: r.raftLog.lastIndex()})
+	} else {
+		log.Printf("raft: %x [commit: %d] ignored snapshot [index: %d, term: %d]",
+			r.id, r.Commit, sindex, sterm)
+		r.send(pb.Message{To: m.From, Type: pb.MsgAppResp, Index: r.raftLog.committed})
+	}
+}
+
 // restore recovers the statemachine from a snapshot. It restores the log and the
 // configuration of statemachine.
 func (r *raft) restore(s pb.Snapshot) bool {
@@ -632,15 +604,31 @@ func (r *raft) needSnapshot(i uint64) bool {
 	return i < r.raftLog.firstIndex()
 }
 
-func (r *raft) nodes() []uint64 {
-	nodes := make([]uint64, 0, len(r.prs))
-	for k := range r.prs {
-		nodes = append(nodes, k)
+// promotable indicates whether state machine can be promoted to leader,
+// which is true when its own id is in progress list.
+func (r *raft) promotable() bool {
+	_, ok := r.prs[r.id]
+	return ok
+}
+
+func (r *raft) addNode(id uint64) {
+	if _, ok := r.prs[id]; ok {
+		// Ignore any redundant addNode calls (which can happen because the
+		// initial bootstrapping entries are applied twice).
+		return
 	}
-	sort.Sort(uint64Slice(nodes))
-	return nodes
+
+	r.setProgress(id, 0, r.raftLog.lastIndex()+1)
+	r.pendingConf = false
+}
+
+func (r *raft) removeNode(id uint64) {
+	r.delProgress(id)
+	r.pendingConf = false
 }
 
+func (r *raft) resetPendingConf() { r.pendingConf = false }
+
 func (r *raft) setProgress(id, match, next uint64) {
 	r.prs[id] = &progress{next: next, match: match}
 }
@@ -649,13 +637,6 @@ func (r *raft) delProgress(id uint64) {
 	delete(r.prs, id)
 }
 
-// promotable indicates whether state machine can be promoted to leader,
-// which is true when its own id is in progress list.
-func (r *raft) promotable() bool {
-	_, ok := r.prs[r.id]
-	return ok
-}
-
 func (r *raft) loadState(state pb.HardState) {
 	if state.Commit < r.raftLog.committed || state.Commit > r.raftLog.lastIndex() {
 		log.Panicf("raft: %x state.commit %d is out of range [%d, %d]", r.id, state.Commit, r.raftLog.committed, r.raftLog.lastIndex())