seaweedfs/go/weed/weed_server/raft_server.go

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package weed_server
import (
"bytes"
"code.google.com/p/weed-fs/go/glog"
"encoding/json"
"errors"
"fmt"
"github.com/goraft/raft"
"github.com/gorilla/mux"
"io/ioutil"
"net/http"
"net/url"
"strings"
"time"
)
type RaftServer struct {
peers []string // initial peers to join with
raftServer raft.Server
dataDir string
httpAddr string
version string
router *mux.Router
}
func NewRaftServer(r *mux.Router, version string, peers []string, httpAddr string, dataDir string) *RaftServer {
s := &RaftServer{
version: version,
peers: peers,
httpAddr: httpAddr,
dataDir: dataDir,
router: r,
}
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if glog.V(4) {
raft.SetLogLevel(2)
}
var err error
transporter := raft.NewHTTPTransporter("/cluster")
s.raftServer, err = raft.NewServer(s.httpAddr, s.dataDir, transporter, nil, nil, "")
if err != nil {
glog.V(0).Infoln(err)
return nil
}
transporter.Install(s.raftServer, s)
s.raftServer.SetHeartbeatInterval(1 * time.Second)
s.raftServer.SetElectionTimeout(1500 * time.Millisecond)
s.raftServer.Start()
s.router.HandleFunc("/cluster/join", s.joinHandler).Methods("POST")
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s.router.HandleFunc("/cluster/status", s.statusHandler).Methods("GET")
// Join to leader if specified.
if len(s.peers) > 0 {
glog.V(0).Infoln("Joining cluster:", strings.Join(s.peers, ","))
if !s.raftServer.IsLogEmpty() {
glog.V(0).Infoln("Cannot join with an existing log")
}
if err := s.Join(s.peers); err != nil {
return nil
}
glog.V(0).Infoln("Joined cluster")
// Initialize the server by joining itself.
} else if s.raftServer.IsLogEmpty() {
glog.V(0).Infoln("Initializing new cluster")
_, err := s.raftServer.Do(&raft.DefaultJoinCommand{
Name: s.raftServer.Name(),
ConnectionString: "http://" + s.httpAddr,
})
if err != nil {
glog.V(0).Infoln(err)
return nil
}
} else {
glog.V(0).Infoln("Recovered from log")
}
return s
}
func (s *RaftServer) IsLeader() bool {
return s.Leader() == s.raftServer.Name()
}
func (s *RaftServer) Leader() string {
l := s.raftServer.Leader()
if l == "" {
// We are a single node cluster, we are the leader
return s.raftServer.Name()
}
return l
}
func (s *RaftServer) Peers() (members []string) {
peers := s.raftServer.Peers()
for _, p := range peers {
members = append(members, strings.TrimPrefix(p.ConnectionString, "http://"))
}
return
}
// Join joins an existing cluster.
func (s *RaftServer) Join(peers []string) error {
command := &raft.DefaultJoinCommand{
Name: s.raftServer.Name(),
ConnectionString: "http://" + s.httpAddr,
}
var b bytes.Buffer
json.NewEncoder(&b).Encode(command)
for _, m := range peers {
target := fmt.Sprintf("http://%s/cluster/join", strings.TrimSpace(m))
glog.V(0).Infoln("Attempting to connect to:", target)
err := postFollowingOneRedirect(target, "application/json", &b)
if err != nil {
glog.V(0).Infoln("Post returned error: ", err)
if _, ok := err.(*url.Error); ok {
// If we receive a network error try the next member
continue
}
return err
}
return nil
}
return errors.New("Could not connect to any cluster peers")
}
// a workaround because http POST following redirection misses request body
func postFollowingOneRedirect(target string, contentType string, b *bytes.Buffer) error {
backupReader := bytes.NewReader(b.Bytes())
resp, err := http.Post(target, contentType, b)
if err != nil {
return err
}
defer resp.Body.Close()
reply, _ := ioutil.ReadAll(resp.Body)
statusCode := resp.StatusCode
if statusCode == http.StatusMovedPermanently {
var urlStr string
if urlStr = resp.Header.Get("Location"); urlStr == "" {
return errors.New(fmt.Sprintf("%d response missing Location header", resp.StatusCode))
}
glog.V(0).Infoln("Post redirected to ", urlStr)
resp2, err2 := http.Post(urlStr, contentType, backupReader)
if err2 != nil {
return err2
}
defer resp2.Body.Close()
reply, _ = ioutil.ReadAll(resp2.Body)
statusCode = resp2.StatusCode
}
glog.V(0).Infoln("Post returned status: ", statusCode, string(reply))
if statusCode != http.StatusOK {
return errors.New(string(reply))
}
return nil
}