// Start the raft server
func (s *PeerServer) Start(snapshot bool, cluster []string) error {
// LoadSnapshot
if snapshot {
err := s.raftServer.LoadSnapshot()
if err == nil {
log.Debugf("%s finished load snapshot", s.Config.Name)
} else {
log.Debug(err)
}
}
s.raftServer.Start()
if s.raftServer.IsLogEmpty() {
// start as a leader in a new cluster
if len(cluster) == 0 {
s.startAsLeader()
} else {
s.startAsFollower(cluster)
}
} else {
// Rejoin the previous cluster
cluster = s.registry.PeerURLs(s.raftServer.Leader(), s.Config.Name)
for i := 0; i < len(cluster); i++ {
u, err := url.Parse(cluster[i])
if err != nil {
log.Debug("rejoin cannot parse url: ", err)
}
cluster[i] = u.Host
}
ok := s.joinCluster(cluster)
if !ok {
log.Warn("the entire cluster is down! this peer will restart the cluster.")
}
log.Debugf("%s restart as a follower", s.Config.Name)
}
s.closeChan = make(chan bool)
go s.monitorSync()
go s.monitorTimeoutThreshold(s.closeChan)
// open the snapshot
if snapshot {
go s.monitorSnapshot()
}
return nil
}
// Join a server to the cluster
func (c *JoinCommand) Apply(context raft.Context) (interface{}, error) {
ps, _ := context.Server().Context().(*PeerServer)
b := make([]byte, 8)
binary.PutUvarint(b, context.CommitIndex())
// Make sure we're not getting a cached value from the registry.
ps.registry.Invalidate(c.Name)
// Check if the join command is from a previous peer, who lost all its previous log.
if _, ok := ps.registry.ClientURL(c.Name); ok {
return b, nil
}
// Check peer number in the cluster
if ps.registry.Count() == ps.Config.MaxClusterSize {
log.Debug("Reject join request from ", c.Name)
return []byte{0}, etcdErr.NewError(etcdErr.EcodeNoMorePeer, "", context.CommitIndex())
}
// Add to shared peer registry.
ps.registry.Register(c.Name, c.RaftURL, c.EtcdURL)
// Add peer in raft
err := context.Server().AddPeer(c.Name, "")
// Add peer stats
if c.Name != ps.RaftServer().Name() {
ps.followersStats.Followers[c.Name] = &raftFollowerStats{}
ps.followersStats.Followers[c.Name].Latency.Minimum = 1 << 63
}
return b, err
}
// Send join requests to peer.
func (s *PeerServer) joinByPeer(server raft.Server, peer string, scheme string) error {
var b bytes.Buffer
// t must be ok
t, _ := server.Transporter().(*transporter)
// Our version must match the leaders version
versionURL := url.URL{Host: peer, Scheme: scheme, Path: "/version"}
version, err := getVersion(t, versionURL)
if err != nil {
return fmt.Errorf("Error during join version check: %v", err)
}
if version < store.MinVersion() || version > store.MaxVersion() {
return fmt.Errorf("Unable to join: cluster version is %d; version compatibility is %d - %d", version, store.MinVersion(), store.MaxVersion())
}
json.NewEncoder(&b).Encode(NewJoinCommand(store.MinVersion(), store.MaxVersion(), server.Name(), s.Config.URL, s.server.URL()))
joinURL := url.URL{Host: peer, Scheme: scheme, Path: "/join"}
log.Debugf("Send Join Request to %s", joinURL.String())
resp, req, err := t.Post(joinURL.String(), &b)
for {
if err != nil {
return fmt.Errorf("Unable to join: %v", err)
}
if resp != nil {
defer resp.Body.Close()
t.CancelWhenTimeout(req)
if resp.StatusCode == http.StatusOK {
b, _ := ioutil.ReadAll(resp.Body)
s.joinIndex, _ = binary.Uvarint(b)
return nil
}
if resp.StatusCode == http.StatusTemporaryRedirect {
address := resp.Header.Get("Location")
log.Debugf("Send Join Request to %s", address)
json.NewEncoder(&b).Encode(NewJoinCommand(store.MinVersion(), store.MaxVersion(), server.Name(), s.Config.URL, s.server.URL()))
resp, req, err = t.Post(address, &b)
} else if resp.StatusCode == http.StatusBadRequest {
log.Debug("Reach max number peers in the cluster")
decoder := json.NewDecoder(resp.Body)
err := &etcdErr.Error{}
decoder.Decode(err)
return *err
} else {
return fmt.Errorf("Unable to join")
}
}
}
}
// Set the key-value pair if the current value of the key equals to the given prevValue
func (c *CompareAndDeleteCommand) Apply(server raft.Server) (interface{}, error) {
s, _ := server.StateMachine().(store.Store)
e, err := s.CompareAndDelete(c.Key, c.PrevValue, c.PrevIndex)
if err != nil {
log.Debug(err)
return nil, err
}
return e, nil
}
// Set the key-value pair if the current value of the key equals to the given prevValue
func (c *CompareAndSwapCommand) Apply(context raft.Context) (interface{}, error) {
s, _ := context.Server().StateMachine().(store.Store)
e, err := s.CompareAndSwap(c.Key, c.PrevValue, c.PrevIndex, c.Value, c.ExpireTime)
if err != nil {
log.Debug(err)
return nil, err
}
return e, nil
}
// Create node
func (c *CreateCommand) Apply(context raft.Context) (interface{}, error) {
s, _ := context.Server().StateMachine().(store.Store)
e, err := s.Create(c.Key, c.Dir, c.Value, c.Unique, c.ExpireTime)
if err != nil {
log.Debug(err)
return nil, err
}
return e, nil
}
// Create node
func (c *SetCommand) Apply(context raft.Context) (interface{}, error) {
s, _ := context.Server().StateMachine().(store.Store)
// create a new node or replace the old node.
e, err := s.Set(c.Key, c.Dir, c.Value, c.ExpireTime)
if err != nil {
log.Debug(err)
return nil, err
}
return e, nil
}
// Delete the key
func (c *DeleteCommand) Apply(context raft.Context) (interface{}, error) {
s, _ := context.Server().StateMachine().(store.Store)
if c.Recursive {
// recursive implies dir
c.Dir = true
}
e, err := s.Delete(c.Key, c.Dir, c.Recursive)
if err != nil {
log.Debug(err)
return nil, err
}
return e, nil
}
// Adds a server handler to the router.
func (s *Server) handleFunc(r *mux.Router, path string, f func(http.ResponseWriter, *http.Request) error) *mux.Route {
// Wrap the standard HandleFunc interface to pass in the server reference.
return r.HandleFunc(path, func(w http.ResponseWriter, req *http.Request) {
// Log request.
log.Debugf("[recv] %s %s %s [%s]", req.Method, s.URL(), req.URL.Path, req.RemoteAddr)
// Execute handler function and return error if necessary.
if err := f(w, req); err != nil {
if etcdErr, ok := err.(*etcdErr.Error); ok {
log.Debug("Return error: ", (*etcdErr).Error())
w.Header().Set("Content-Type", "application/json")
etcdErr.Write(w)
} else {
http.Error(w, err.Error(), http.StatusInternalServerError)
}
}
})
}
// Response to the join request
func (ps *PeerServer) JoinHttpHandler(w http.ResponseWriter, req *http.Request) {
command := &JoinCommand{}
err := uhttp.DecodeJsonRequest(req, command)
if err != nil {
w.WriteHeader(http.StatusInternalServerError)
return
}
log.Debugf("Receive Join Request from %s", command.Name)
err = ps.server.Dispatch(command, w, req)
// Return status.
if err != nil {
if etcdErr, ok := err.(*etcdErr.Error); ok {
log.Debug("Return error: ", (*etcdErr).Error())
etcdErr.Write(w)
} else {
http.Error(w, err.Error(), http.StatusInternalServerError)
}
}
}
