/
cluster.go
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/
cluster.go
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// Copyright (c) 2019 Kien Nguyen-Tuan <kiennt2609@gmail.com>
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package cluster
import (
"encoding/json"
"fmt"
"net"
"os"
"strings"
"sync"
"github.com/go-kit/kit/log"
"github.com/go-kit/kit/log/level"
"github.com/pkg/errors"
etcdv3 "go.etcd.io/etcd/clientv3"
"stathat.com/c/consistent"
"github.com/vCloud-DFTBA/faythe/pkg/common"
"github.com/vCloud-DFTBA/faythe/pkg/exporter"
"github.com/vCloud-DFTBA/faythe/pkg/model"
)
var clusterID string
// State is the state of the Cluster instance
type State int
const (
// DefaultLeaseTTL etcd lease time-to-live in seconds
DefaultLeaseTTL int64 = 10
ClusterAlive State = iota
ClusterLeaving
ClusterLeft
ClusterJoining
)
func (s State) String() string {
switch s {
case ClusterAlive:
return "alive"
case ClusterJoining:
return "joining"
case ClusterLeft:
return "left"
case ClusterLeaving:
return "leaving"
default:
return "unknown"
}
}
// GetID makes cluster id be available
// across modules.
func GetID() string {
return clusterID
}
// Cluster manages a set of member and the consistent hash ring as well.
type Cluster struct {
id string
logger log.Logger
lease etcdv3.LeaseID
local model.Member
members map[string]model.Member
etcdcli *common.Etcd
ring *consistent.Consistent
stopCh chan struct{}
state State
stateLock sync.RWMutex
}
// New creates a new cluster manager instance.
func New(id string, bindAddr string, l log.Logger, e *common.Etcd) (*Cluster, error) {
clusterID = id
c := &Cluster{
logger: l,
etcdcli: e,
members: make(map[string]model.Member),
stopCh: make(chan struct{}),
}
level.Info(c.logger).Log("msg", "Use the cluster id to join", "id", clusterID)
c.id = id
// Load the existing cluster
getResp, _ := c.etcdcli.DoGet(model.DefaultClusterPrefix, etcdv3.WithPrefix())
for _, kv := range getResp.Kvs {
var m model.Member
_ = json.Unmarshal(kv.Value, &m)
c.members[m.ID] = m
}
// Init a local member
local, err := newLocalMember(bindAddr)
if err != nil {
return c, err
}
c.local = local
// Join the cluster
if err = c.join(); err != nil {
return c, err
}
return c, nil
}
// getState returns the current state of this Cluster instance
func (c *Cluster) getState() State {
c.stateLock.RLock()
defer c.stateLock.RUnlock()
return c.state
}
// setState for safety update the state
func (c *Cluster) setState(new State) {
c.stateLock.Lock()
defer c.stateLock.Unlock()
c.state = new
}
func (c *Cluster) join() error {
c.setState(ClusterJoining)
grantResp, err := c.etcdcli.DoGrant(DefaultLeaseTTL)
if err != nil {
return err
}
c.lease = grantResp.ID
if _, ok := c.members[c.local.ID]; !ok {
c.members[c.local.ID] = c.local
// Add new member
v, _ := json.Marshal(&c.local)
_, err := c.etcdcli.DoPut(common.Path(model.DefaultClusterPrefix, c.local.ID),
string(v), etcdv3.WithLease(c.lease))
level.Debug(c.logger).Log("msg", "The current cluster state",
"members", fmt.Sprintf("%+v", c.members))
if err != nil {
return err
}
} else {
return errors.Errorf("a node %s is already cluster member", c.local.Name)
}
// This will keep the key alive 'forever' or until we revoke it
// or the connect is canceled.
err = c.etcdcli.DoKeepAlive(c.lease)
if err != nil {
return err
}
c.setState(ClusterAlive)
exporter.RegisterMemberInfo(c.id, c.local)
// Init a HashRing
c.ring = consistent.New()
for _, m := range c.members {
c.ring.Add(m.ID)
}
return nil
}
func (c *Cluster) leave() {
c.setState(ClusterLeaving)
level.Info(c.logger).Log("msg", "The local member of cluster is leaving...",
"name", c.local.Name, "address", c.local.Address)
_, err := c.etcdcli.DoDelete(common.Path(model.DefaultClusterPrefix, c.local.ID),
etcdv3.WithIgnoreLease())
if err != nil {
level.Error(c.logger).Log("msg", "Error leaving the cluster",
"name", c.local.Name, "address", c.local.Address)
}
c.setState(ClusterLeft)
level.Info(c.logger).Log("msg", "The local member of cluster is left",
"name", c.local.Name, "address", c.local.Address)
}
// Run watches the cluster state's changes and does its job
func (c *Cluster) Run(rc chan struct{}) {
ctx, cancel := c.etcdcli.WatchContext()
watch := c.etcdcli.Watch(ctx, model.DefaultClusterPrefix,
etcdv3.WithPrefix(), etcdv3.WithCreatedNotify())
defer func() { cancel() }()
for {
select {
case <-c.stopCh:
return
case <-ctx.Done():
return
case watchResp := <-watch:
reload := false
if err := watchResp.Err(); err != nil {
level.Error(c.logger).Log("msg", "Error watching cluster state", "err", err)
eerr := common.NewEtcdErr(model.DefaultClusterPrefix, "watch", err)
c.etcdcli.ErrCh <- eerr
return
}
for _, event := range watchResp.Events {
switch event.Type {
case etcdv3.EventTypePut:
var m model.Member
err := json.Unmarshal(event.Kv.Value, &m)
if err != nil {
level.Error(c.logger).Log("msg", "Error unmarshaling event value",
"err", err)
continue
}
level.Info(c.logger).Log("msg", "A new member is joined",
"name", m.Name, "address", m.Address)
c.ring.Add(m.ID)
exporter.ReportClusterJoin()
c.members[m.ID] = m
case etcdv3.EventTypeDelete:
id := strings.TrimPrefix(string(event.Kv.Key), model.DefaultClusterPrefix)
id = strings.Trim(id, "/")
level.Info(c.logger).Log("msg", "A member is left",
"name", c.members[id].Name, "address", c.members[id].Address)
c.ring.Remove(id)
exporter.ReportClusterLeave()
delete(c.members, id)
}
level.Debug(c.logger).Log("msg", "The current cluster state",
"members", fmt.Sprintf("%+v", c.members))
reload = true
}
// Reload only if there is at least one correct event
if reload {
rc <- struct{}{}
}
}
}
}
// Stop stops the member as well as the watch process
func (c *Cluster) Stop() {
if c.getState() == ClusterLeaving || c.getState() == ClusterLeft {
return
}
close(c.stopCh)
c.leave()
level.Info(c.logger).Log("msg", "The local member of cluster is stopped",
"name", c.local.Name, "address", c.local.Address)
}
// LocalIsWorker checks if the local node is the worker which has
// responsibility for the given string key.
func (c *Cluster) LocalIsWorker(key string) (string, string, bool) {
workerID, _ := c.ring.Get(key)
worker := c.members[workerID]
// Return the node name, it will be easier for user.
return c.local.Name, worker.Name, workerID == c.local.ID
}
// LocalMember returns the local node member.
func (c *Cluster) LocalMember() model.Member {
return c.local
}
func newLocalMember(bindAddr string) (model.Member, error) {
m := model.Member{}
hostname, err := os.Hostname()
if err != nil {
return m, err
}
m.Name = hostname
host, _, _ := net.SplitHostPort(bindAddr)
// If there is no bind IP, pick an address
if host == "0.0.0.0" {
host, err = common.ExternalIP()
if err != nil {
return m, err
}
}
m.Address = host
if err := m.Validate(); err != nil {
return m, err
}
return m, nil
}