/
cluster.go
647 lines (554 loc) · 15.7 KB
/
cluster.go
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package server
import (
"encoding/json"
"errors"
"fmt"
"io"
"net/http"
"os"
"path"
"strconv"
"strings"
"sync"
"time"
"github.com/golang/glog"
"github.com/hashicorp/memberlist"
"github.com/pborman/uuid"
localConfig "github.com/deatheyes/MysqlProbe/config"
)
// lables of role
const (
NodeRoleSlave = "slave"
NodeRoleMaster = "master"
NodeRoleStandby = "standby"
)
// seeds file to store and reload cluster nodes
const (
SeedsFileName = "seeds.yaml"
)
// Broadcast is the implicment of memberlists' Broadcast
type Broadcast struct {
msg []byte
notify chan<- struct{}
}
func (b *Broadcast) Invalidates(other memberlist.Broadcast) bool {
return false
}
func (b *Broadcast) Message() []byte {
return b.msg
}
func (b *Broadcast) Finished() {
if b.notify != nil {
close(b.notify)
}
}
// MetaData keeps the base infomation of a node
type MetaData struct {
Role string `json:"role"` // master, standy, probe
Epic uint64 `json:"epic"` // epic for message checking
Group string `json:"group"` // group(cluster) name
ServerPort uint16 `json:"server_port"` // dispatcher port
}
// Node contains the unit's topology
type Node struct {
Name string `json:"name"`
IP string `json:"ip"`
GossipPort uint16 `json:"gossip_port"`
Meta *MetaData `json:"meta"`
}
// DistributedSystem decide how the cluster works
type DistributedSystem interface {
Run()
Join(addr string) error
Remove(addr string) error
Leave() error
ListNodes() ([]byte, error)
ConfigUpdate(key string, val string) error
}
// GossipSystem is an auto failure dectect distributed system
type GossipSystem struct {
server *Server // owner
meta *MetaData // local meta
master string // master of current cluster
seeds []string // seeds to join
list *memberlist.Memberlist
broadcasts *memberlist.TransmitLimitedQueue
localIP string
localPort uint16
port uint16
name string // node name in the cluster
seedsFilePath string // seeds file for boot, usually used when restart
sync.Mutex
}
// NewGossipSystem create a new gossip based system
func NewGossipSystem(server *Server, role string, group string, port uint16) *GossipSystem {
dir := path.Dir(server.config.Path)
seedsFilePath := path.Join(dir, SeedsFileName)
return &GossipSystem{
server: server,
meta: &MetaData{Role: role, Epic: 0, Group: group, ServerPort: server.config.Port},
port: port,
seedsFilePath: seedsFilePath,
}
}
func (d *GossipSystem) writeSeeds() {
if d.list == nil || d.list.Members() == nil {
// list is not inited
return
}
var addrs []string
for _, m := range d.list.Members() {
addrs = append(addrs, fmt.Sprintf("%v:%v", m.Addr.String(), m.Port))
}
seeds := &localConfig.Seeds{Addrs: addrs, Epic: d.meta.Epic, Name: d.name, Role: d.meta.Role}
if err := localConfig.SeedsToFile(seeds, d.seedsFilePath); err != nil {
glog.Warningf("write seeds failed: %v", err)
}
glog.V(7).Infof("write seeds to %v done", d.seedsFilePath)
}
// Run initiliaze and start the system
func (d *GossipSystem) Run() {
hostname, _ := os.Hostname()
config := memberlist.DefaultWANConfig()
config.Delegate = d
config.Events = d
config.Alive = d
config.BindPort = int(d.port)
config.Name = hostname + "-" + uuid.NewUUID().String()
if d.meta.Role == NodeRoleMaster {
d.master = config.Name
} else {
d.master = ""
}
// try load seeds from file
if _, err := os.Stat(d.seedsFilePath); os.IsNotExist(err) {
glog.Info("no seeds to start cluster")
d.name = config.Name
list, err := memberlist.Create(config)
if err != nil {
glog.Fatalf("init distributed system failed: %v", err)
}
d.list = list
n := d.list.LocalNode()
d.localIP = n.Addr.String()
d.localPort = uint16(n.Port)
} else {
// override the config with seeds
seeds, err := localConfig.SeedsFromFile(d.seedsFilePath)
if err != nil {
glog.Fatalf("load seeds failed: %v", err)
return
}
switch seeds.Role {
case NodeRoleMaster, NodeRoleSlave, NodeRoleStandby:
d.meta.Role = seeds.Role
default:
glog.Warningf("unkonwn role: %v", seeds.Role)
}
d.meta.Epic = seeds.Epic
if len(seeds.Name) != 0 {
config.Name = seeds.Name
d.name = seeds.Name
}
list, err := memberlist.Create(config)
if err != nil {
glog.Fatalf("init distributed system with seeds %v failed: %v", seeds, err)
}
d.list = list
n := d.list.LocalNode()
d.localIP = n.Addr.String()
d.localPort = uint16(n.Port)
// try to join the cluster recorded by seeds
if len(seeds.Addrs) > 0 {
glog.Infof("init distributed system by addresses: %v", seeds.Addrs)
if _, err := d.list.Join(seeds.Addrs); err != nil {
glog.Fatalf("join seeds failed: %v", err)
return
}
}
}
d.broadcasts = &memberlist.TransmitLimitedQueue{
NumNodes: func() int {
return d.list.NumMembers()
},
RetransmitMult: 3,
}
glog.Infof("init distributed system done, local member %s:%d, name: %v", d.localIP, d.localPort, d.name)
}
// delegate
// NodeMeta reutrn the binary meta data
func (d *GossipSystem) NodeMeta(limit int) []byte {
data, err := json.Marshal(d.meta)
if err != nil {
glog.Warningf("marshal meta failed: %v", err)
return nil
}
return data
}
func (d *GossipSystem) NotifyMsg(b []byte) {}
func (d *GossipSystem) GetBroadcasts(overhead, limit int) [][]byte {
return d.broadcasts.GetBroadcasts(overhead, limit)
}
func (d *GossipSystem) LocalState(join bool) []byte {
return nil
}
func (d *GossipSystem) MergeRemoteState(buf []byte, join bool) {
}
// OnRoleChanged is a callback to process nodes' role changed
func (d *GossipSystem) OnRoleChanged(oldRole, newRole string) {
glog.V(5).Infof("my role change form %v to %v", oldRole, newRole)
switch newRole {
case NodeRoleMaster:
// start collect data from nodes
d.server.collector.EnableConnection()
// create connection for all slaves
for _, m := range d.list.Members() {
meta := &MetaData{}
if err := json.Unmarshal(m.Meta, meta); err != nil {
glog.Warningf("unmarshal meta failed: %v", err)
continue
}
if meta.Role == NodeRoleSlave {
d.server.collector.AddNode(fmt.Sprintf("%s:%d", m.Addr.String(), meta.ServerPort))
}
}
default:
// clean all node in collector
d.server.collector.DisableConnection()
}
}
func (d *GossipSystem) checkPromotion(meta *MetaData, node *memberlist.Node) {
if meta.Role == NodeRoleMaster {
// check if need to update status
if d.meta.Epic < meta.Epic || (d.meta.Epic == meta.Epic && strings.Compare(d.master, node.Name) < 0) {
d.meta.Epic = meta.Epic
d.master = node.Name
if d.meta.Role == NodeRoleMaster {
// switch to standby
d.meta.Role = NodeRoleStandby
d.OnRoleChanged(NodeRoleMaster, NodeRoleStandby)
}
}
}
}
// event delegate
// NotifyJoin is called when a node join the cluster
func (d *GossipSystem) NotifyJoin(node *memberlist.Node) {
if node.Name == d.name {
return
}
meta := &MetaData{}
if err := json.Unmarshal(node.Meta, meta); err != nil {
glog.Warningf("unmarshal meta failed: %v", err)
return
}
d.Lock()
defer d.Unlock()
d.checkPromotion(meta, node)
// see if need to add node to collector
if d.meta.Role == NodeRoleMaster && meta.Role == NodeRoleSlave {
// we are the master, and found a new slave
d.server.collector.AddNode(fmt.Sprintf("%s:%d", node.Addr.String(), meta.ServerPort))
}
// update seeds
go d.writeSeeds()
}
// NotifyUpdate is called when a node change its gossip message
func (d *GossipSystem) NotifyUpdate(node *memberlist.Node) {
meta := &MetaData{}
if err := json.Unmarshal(node.Meta, meta); err != nil {
glog.Warningf("unmarshal meta failed: %v", err)
return
}
d.Lock()
defer d.Unlock()
d.checkPromotion(meta, node)
// currently, role could not be switched between slave and master|standby.
}
// NotifyLeave is called when a node leave the gossip cluster
func (d *GossipSystem) NotifyLeave(node *memberlist.Node) {
meta := &MetaData{}
if err := json.Unmarshal(node.Meta, meta); err != nil {
glog.Warningf("unmarshal meta failed: %v", err)
return
}
d.Lock()
defer d.Unlock()
if meta.Role == NodeRoleMaster {
// check if need an election, only standby could start an election.
if d.master == node.Name {
// master left
if d.meta.Role == NodeRoleStandby {
// start an election
d.meta.Epic++
d.meta.Role = NodeRoleMaster
d.OnRoleChanged(NodeRoleStandby, NodeRoleMaster)
}
}
}
if d.meta.Role == NodeRoleMaster && meta.Role == NodeRoleSlave {
// remove the left slave node from collector
d.server.collector.RemoveNode(fmt.Sprintf("%s:%d", node.Addr.String(), meta.ServerPort))
}
go d.writeSeeds()
}
// NotifyAlive is a interface called by the heart beat scheme of memberlist
func (d *GossipSystem) NotifyAlive(peer *memberlist.Node) error {
meta := &MetaData{}
if err := json.Unmarshal(peer.Meta, meta); err != nil {
glog.Warningf("unmarshal meta failed: %v", err)
return fmt.Errorf("unmarshal meta failed: %v", err)
}
d.Lock()
defer d.Unlock()
// reject those who is not the same group as us.
if meta.Group != d.meta.Group {
return fmt.Errorf("unexpected gorup: %v", meta.Group)
}
return nil
}
// Join add a node specified by 'addr' into cluster
func (d *GossipSystem) Join(addr string) error {
if _, err := d.list.Join([]string{addr}); err != nil {
return err
}
return nil
}
var leavetimeout = 10 * time.Second
// Leave removes current node from cluster
func (d *GossipSystem) Leave() error {
if err := d.list.Leave(leavetimeout); err != nil {
return err
}
return nil
}
// Remove is not supported in gossip system
func (d *GossipSystem) Remove(addr string) error {
return errors.New("gossip system don't support this interface")
}
// ListNodes shows cluster nodes info
func (d *GossipSystem) ListNodes() ([]byte, error) {
nodes := []*Node{}
for _, m := range d.list.Members() {
meta := &MetaData{}
if err := json.Unmarshal(m.Meta, meta); err != nil {
glog.Warningf("unmarshal meta failed: %v", err)
continue
}
nodes = append(nodes, &Node{Name: m.Name, IP: m.Addr.String(), GossipPort: uint16(m.Port), Meta: meta})
}
data, err := json.Marshal(nodes)
if err != nil {
return nil, err
}
return data, nil
}
// ConfigUpdate updates a key-value configuration
func (d *GossipSystem) ConfigUpdate(key string, val string) error {
switch key {
case "report_period_ms":
period, err := strconv.ParseInt(val, 10, 64)
if err != nil {
return err
}
d.server.collector.UpdateReportPeriod(time.Duration(period) * time.Millisecond)
return nil
default:
glog.Warningf("unsupport key: %v", key)
return errors.New("unsupport key")
}
}
// StaticSystem is a mannually control distributed system
type StaticSystem struct {
server *Server // owner
role string // role of this node
nodes map[string]*Node // slaves' info
group string // cluster group
seedsFilePath string // cluster nodes file, usually used when restart
sync.Mutex
}
// NewStaticSystem ...
// there is no standby static system
// slave can only added by master
func NewStaticSystem(server *Server, role string, group string) *StaticSystem {
dir := path.Dir(server.config.Path)
seedsFilePath := path.Join(dir, SeedsFileName)
return &StaticSystem{
server: server,
role: role,
group: group,
nodes: make(map[string]*Node),
seedsFilePath: seedsFilePath,
}
}
func (d *StaticSystem) addNodeByAddr(addr string) error {
if _, ok := d.nodes[addr]; !ok {
ss := strings.Split(addr, ":")
if len(ss) != 2 {
return fmt.Errorf("unexpected address: %v", addr)
}
port, err := strconv.ParseUint(ss[1], 10, 16)
if err != nil {
return err
}
d.server.collector.AddNode(addr)
d.nodes[addr] = &Node{
Name: addr,
IP: ss[0],
GossipPort: 0,
Meta: &MetaData{
Role: NodeRoleSlave,
Epic: 0,
ServerPort: uint16(port),
Group: d.group,
},
}
}
// update cluster file
d.writeSeeds()
return nil
}
// Run starts the StaticSystem
func (d *StaticSystem) Run() {
// slaves don't need the seeds
if d.role == NodeRoleSlave {
return
}
// try load cluster from seeds
if _, err := os.Stat(d.seedsFilePath); os.IsNotExist(err) {
glog.Info("no seeds to start cluster")
} else {
seeds, err := localConfig.SeedsFromFile(d.seedsFilePath)
if err != nil {
glog.Fatalf("load seeds failed: %v", err)
}
for _, addr := range seeds.Addrs {
if err := d.addNodeByAddr(addr); err != nil {
glog.Warningf("load node %v failed: %v", addr, err)
}
}
}
}
func (d *StaticSystem) writeSeeds() {
var addrs []string
for k := range d.nodes {
addrs = append(addrs, k)
}
// we must sure not to miss any nodes, so block and update cluster nodes file
seeds := &localConfig.Seeds{Addrs: addrs}
if err := localConfig.SeedsToFile(seeds, d.seedsFilePath); err != nil {
glog.Warningf("write seed to %v failed: %v", d.seedsFilePath, err)
}
glog.V(7).Infof("write seed to %v done", d.seedsFilePath)
}
// ErrNotMaster returned when the node is not master
var ErrNotMaster = errors.New("not master")
// Join adds a node specified by 'addr' to current cluster
func (d *StaticSystem) Join(addr string) error {
// only master could join slave
if d.role != NodeRoleMaster {
return ErrNotMaster
}
d.Lock()
defer d.Unlock()
return d.addNodeByAddr(addr)
}
// Leave remove current node from its cluster
func (d *StaticSystem) Leave() error {
if d.role != NodeRoleMaster {
return ErrNotMaster
}
d.Lock()
defer d.Unlock()
d.server.collector.DisableConnection()
// update cluster file
d.writeSeeds()
return nil
}
// Remove delete a node specified by 'addr' from current cluster
func (d *StaticSystem) Remove(addr string) error {
// only master could remove slave
if d.role != NodeRoleMaster {
return ErrNotMaster
}
d.Lock()
defer d.Unlock()
if _, ok := d.nodes[addr]; ok {
d.server.collector.RemoveNode(addr)
delete(d.nodes, addr)
}
// update cluster file
d.writeSeeds()
return nil
}
// ListNodes show cluster topology
func (d *StaticSystem) ListNodes() ([]byte, error) {
if d.role != NodeRoleMaster {
return nil, ErrNotMaster
}
d.Lock()
defer d.Unlock()
nodes := []*Node{}
for _, n := range d.nodes {
nodes = append(nodes, n)
}
data, err := json.Marshal(nodes)
if err != nil {
return nil, err
}
return data, nil
}
// ConfigUpdate react to dynamic config change
func (d *StaticSystem) ConfigUpdate(key string, val string) error {
switch key {
case "report_period_ms":
// update myself
period, err := strconv.ParseInt(val, 10, 64)
if err != nil {
return err
}
d.server.collector.UpdateReportPeriod(time.Duration(period) * time.Millisecond)
return nil
default:
glog.Warningf("unsupport key: %v", key)
return errors.New("unsupport key")
}
}
// http handle function
func serveJoin(d DistributedSystem, w http.ResponseWriter, r *http.Request) {
r.ParseForm()
addr := r.Form.Get("addr")
if err := d.Join(addr); err != nil {
http.Error(w, err.Error(), 500)
return
}
io.WriteString(w, "OK")
}
func serveLeave(d DistributedSystem, w http.ResponseWriter, r *http.Request) {
if err := d.Leave(); err != nil {
glog.Warningf("leave cluster failed: %v", err)
http.Error(w, err.Error(), 500)
return
}
io.WriteString(w, "OK")
}
func serveListNodes(d DistributedSystem, w http.ResponseWriter, r *http.Request) {
data, err := d.ListNodes()
if err != nil {
glog.Warningf("list cluster nodes failed: %v", err)
http.Error(w, err.Error(), 500)
return
}
io.WriteString(w, string(data))
}
func serveConfigUpdate(d DistributedSystem, w http.ResponseWriter, r *http.Request) {
r.ParseForm()
key := "report_period_ms"
val := r.Form.Get(key)
if err := d.ConfigUpdate(key, val); err != nil {
glog.Warningf("update config failed, key: %v val: %v err: %v", key, val, err)
http.Error(w, err.Error(), 500)
return
}
io.WriteString(w, "OK")
}