wip/ move write/read to server.go and add test

config.go

@@ -1,84 +1,7 @@
 package raft
 
-import (
+type Config struct {
-	"encoding/json"
+	CommitIndex uint64 `json:"commitIndex"`
-	"io/ioutil"
-	"os"
-	"path"
-)
-
-type RaftConfig struct {
-	KnownCommitIndex uint64 `json:"KnownCommitIndex"`
 	// TODO decide what we need to store in peer struct
-	Peers []string `json:"Peers"`
+	Peers []string `json:"peers"`
-}
-
-func (s *Server) writeConf() {
-
-	peers := make([]string, len(s.peers))
-
-	i := 0
-	for peer := range s.peers {
-		peers[i] = peer
-		i++
-	}
-
-	r := &RaftConfig{
-		KnownCommitIndex: s.log.commitIndex,
-		Peers:            peers,
-	}
-
-	b, _ := json.Marshal(r)
-
-	confBakPath := path.Join(s.path, "conf.bak")
-	confPath := path.Join(s.path, "conf")
-
-	confFile, err := os.OpenFile(confBakPath, os.O_WRONLY|os.O_CREATE, 0600)
-
-	if err != nil {
-		panic(err)
-	}
-
-	confFile.Write(b)
-
-	os.Remove(confPath)
-	os.Rename(confBakPath, confPath)
-}
-
-// Read the configuration for the server.
-func (s *Server) readConf() error {
-	confPath := path.Join(s.path, "conf")
-	s.debugln("readConf.open ", confPath)
-	// open conf file
-	confFile, err := os.OpenFile(confPath, os.O_RDWR, 0600)
-
-	if err != nil {
-		if os.IsNotExist(err) {
-			_, err = os.OpenFile(confPath, os.O_WRONLY|os.O_CREATE, 0600)
-			debugln("readConf.create ", confPath)
-			if err != nil {
-				return err
-			}
-		}
-		return err
-	}
-
-	raftConf := &RaftConfig{}
-
-	b, err := ioutil.ReadAll(confFile)
-	if err != nil {
-		return err
-	}
-
-	confFile.Close()
-
-	err = json.Unmarshal(b, raftConf)
-
-	if err != nil {
-		return err
-	}
-
-	s.log.commitIndex = raftConf.KnownCommitIndex
-
-	return nil
 }

server.go

@@ -927,7 +927,7 @@ func (s *Server) processRequestVoteRequest(req *RequestVoteRequest) (*RequestVot
 // Adds a peer to the server.
 func (s *Server) AddPeer(name string) error {
 	s.debugln("server.peer.add: ", name, len(s.peers))
-
+	defer s.writeConf()
 	// Do not allow peers to be added twice.
 	if s.peers[name] != nil {
 		return nil
@@ -946,7 +946,6 @@ func (s *Server) AddPeer(name string) error {
 
 	s.peers[peer.name] = peer
 
-	s.writeConf()
 	s.debugln("server.peer.conf.write: ", name)
 
 	return nil
@@ -956,11 +955,12 @@ func (s *Server) AddPeer(name string) error {
 func (s *Server) RemovePeer(name string) error {
 	s.debugln("server.peer.remove: ", name, len(s.peers))
 
+	defer s.writeConf()
+
 	if name == s.Name() {
 		// when the removed node restart, it should be able
 		// to know it has been removed before. So we need
 		// to update knownCommitIndex
-		s.writeConf()
 		return nil
 	}
 	// Return error if peer doesn't exist.
@@ -976,8 +976,6 @@ func (s *Server) RemovePeer(name string) error {
 
 	delete(s.peers, name)
 
-	s.writeConf()
-
 	return nil
 }
 
@@ -1208,6 +1206,62 @@ func (s *Server) LoadSnapshot() error {
 	return err
 }
 
+//--------------------------------------
+// Config File
+//--------------------------------------
+
+func (s *Server) writeConf() {
+
+	peers := make([]string, len(s.peers))
+
+	i := 0
+	for peer, _ := range s.peers {
+		peers[i] = peer
+		i++
+	}
+
+	r := &Config{
+		CommitIndex: s.log.commitIndex,
+		Peers:       peers,
+	}
+
+	b, _ := json.Marshal(r)
+
+	confPath := path.Join(s.path, "conf")
+	tmpConfPath := path.Join(s.path, "conf.tmp")
+
+	err := ioutil.WriteFile(tmpConfPath, b, 0600)
+
+	if err != nil {
+		panic(err)
+	}
+
+	os.Rename(tmpConfPath, confPath)
+}
+
+// Read the configuration for the server.
+func (s *Server) readConf() error {
+	confPath := path.Join(s.path, "conf")
+	s.debugln("readConf.open ", confPath)
+
+	// open conf file
+	b, err := ioutil.ReadFile(confPath)
+
+	if err != nil {
+		return nil
+	}
+
+	conf := &Config{}
+
+	if err = json.Unmarshal(b, conf); err != nil {
+		return err
+	}
+
+	s.log.commitIndex = conf.CommitIndex
+
+	return nil
+}
+
 //--------------------------------------
 // Debugging
 //--------------------------------------

server_test.go

@@ -316,6 +316,124 @@ func TestServerDenyCommandExecutionWhenFollower(t *testing.T) {
 	}
 }
 
+//--------------------------------------
+// Recovery
+//--------------------------------------
+
+// Ensure that a follower cannot execute a command.
+func TestServerRecoverFromPreviousLogAndConf(t *testing.T) {
+	// Initialize the servers.
+	var mutex sync.RWMutex
+	servers := map[string]*Server{}
+
+	transporter := &testTransporter{}
+	transporter.sendVoteRequestFunc = func(server *Server, peer *Peer, req *RequestVoteRequest) *RequestVoteResponse {
+		mutex.RLock()
+		s := servers[peer.name]
+		mutex.RUnlock()
+		return s.RequestVote(req)
+	}
+	transporter.sendAppendEntriesRequestFunc = func(server *Server, peer *Peer, req *AppendEntriesRequest) *AppendEntriesResponse {
+		mutex.RLock()
+		s := servers[peer.name]
+		mutex.RUnlock()
+		return s.AppendEntries(req)
+	}
+
+	disTransporter := &testTransporter{}
+	disTransporter.sendVoteRequestFunc = func(server *Server, peer *Peer, req *RequestVoteRequest) *RequestVoteResponse {
+		return nil
+	}
+	disTransporter.sendAppendEntriesRequestFunc = func(server *Server, peer *Peer, req *AppendEntriesRequest) *AppendEntriesResponse {
+		return nil
+	}
+
+	var names []string
+	var paths = make(map[string]string)
+
+	n := 5
+
+	// add n servers
+	for i := 1; i <= n; i++ {
+		names = append(names, strconv.Itoa(i))
+	}
+
+	var leader *Server
+	for _, name := range names {
+		server := newTestServer(name, transporter)
+
+		servers[name] = server
+		paths[name] = server.Path()
+
+		if name == "1" {
+			leader = server
+			server.SetHeartbeatTimeout(testHeartbeatTimeout)
+			server.Start()
+			time.Sleep(testHeartbeatTimeout)
+		} else {
+			server.SetElectionTimeout(testElectionTimeout)
+			server.SetHeartbeatTimeout(testHeartbeatTimeout)
+			server.Start()
+			time.Sleep(testHeartbeatTimeout)
+		}
+		if _, err := leader.Do(&DefaultJoinCommand{Name: name}); err != nil {
+			t.Fatalf("Unable to join server[%s]: %v", name, err)
+		}
+
+	}
+
+	// commit some commands
+	for i := 0; i < 10; i++ {
+		if _, err := leader.Do(&testCommand2{X: 1}); err != nil {
+			t.Fatalf("cannot commit command:", err.Error())
+		}
+	}
+
+	time.Sleep(2 * testHeartbeatTimeout)
+
+	for _, name := range names {
+		server := servers[name]
+		if server.CommitIndex() != 16 {
+			t.Fatalf("%s commitIndex is invalid [%d/%d]", name, server.CommitIndex(), 16)
+		}
+		server.Stop()
+	}
+
+	for _, name := range names {
+		// with old path and disable transportation
+		server := newTestServerWithPath(name, disTransporter, paths[name])
+		servers[name] = server
+
+		server.Start()
+
+		// should only commit to the last join command
+		if server.CommitIndex() != 6 {
+			t.Fatalf("%s recover phase 1 commitIndex is invalid [%d/%d]", name, server.CommitIndex(), 6)
+		}
+
+		// peer conf should be recovered
+		if len(server.Peers()) != 4 {
+			t.Fatalf("%s recover phase 1 peer failed! [%d/%d]", name, len(server.Peers()), 4)
+		}
+	}
+
+	// let nodes talk to each other
+	for _, name := range names {
+		servers[name].SetTransporter(transporter)
+	}
+
+	time.Sleep(2 * testElectionTimeout)
+
+	// should commit to the previous index + 1(nop command when new leader elected)
+	for _, name := range names {
+		server := servers[name]
+		if server.CommitIndex() != 17 {
+			t.Fatalf("%s commitIndex is invalid [%d/%d]", name, server.CommitIndex(), 16)
+		}
+		server.Stop()
+	}
+}
+
 //--------------------------------------
 // Membership
 //--------------------------------------

test.go

@@ -69,6 +69,11 @@ func newTestServer(name string, transporter Transporter) *Server {
 	return server
 }
 
+func newTestServerWithPath(name string, transporter Transporter, p string) *Server {
+	server, _ := NewServer(name, p, transporter, nil, nil)
+	return server
+}
+
 func newTestServerWithLog(name string, transporter Transporter, entries []*LogEntry) *Server {
 	server := newTestServer(name, transporter)
 	f, err := os.Create(server.LogPath())