milvus/internal/util/sessionutil/session_util.go
Enwei Jiao 89b810a4db
Refactor all params into ParamItem (#20987)
Signed-off-by: Enwei Jiao <enwei.jiao@zilliz.com>

Signed-off-by: Enwei Jiao <enwei.jiao@zilliz.com>
2022-12-07 18:01:19 +08:00

858 lines
25 KiB
Go

// Licensed to the LF AI & Data foundation under one
// or more contributor license agreements. See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership. The ASF licenses this file
// to you 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 sessionutil
import (
"context"
"encoding/json"
"errors"
"fmt"
"path"
"strconv"
"sync"
"sync/atomic"
"time"
"github.com/blang/semver/v4"
"github.com/milvus-io/milvus/internal/common"
"github.com/milvus-io/milvus/internal/log"
"github.com/milvus-io/milvus/internal/util/paramtable"
"github.com/milvus-io/milvus/internal/util/retry"
"go.etcd.io/etcd/api/v3/mvccpb"
v3rpc "go.etcd.io/etcd/api/v3/v3rpc/rpctypes"
clientv3 "go.etcd.io/etcd/client/v3"
"go.uber.org/zap"
)
const (
// DefaultServiceRoot default root path used in kv by Session
DefaultServiceRoot = "session/"
// DefaultIDKey default id key for Session
DefaultIDKey = "id"
)
// SessionEventType session event type
type SessionEventType int
func (t SessionEventType) String() string {
switch t {
case SessionAddEvent:
return "SessionAddEvent"
case SessionDelEvent:
return "SessionDelEvent"
case SessionUpdateEvent:
return "SessionUpdateEvent"
default:
return ""
}
}
// Rewatch defines the behavior outer session watch handles ErrCompacted
// it should process the current full list of session
// and returns err if meta error or anything else goes wrong
type Rewatch func(sessions map[string]*Session) error
const (
// SessionNoneEvent place holder for zero value
SessionNoneEvent SessionEventType = iota
// SessionAddEvent event type for a new Session Added
SessionAddEvent
// SessionDelEvent event type for a Session deleted
SessionDelEvent
// SessionUpdateEvent event type for a Session stopping
SessionUpdateEvent
)
// Session is a struct to store service's session, including ServerID, ServerName,
// Address.
// Exclusive indicates that this server can only start one.
type Session struct {
ctx context.Context
// When outside context done, Session cancels its goroutines first, then uses
// keepAliveCancel to cancel the etcd KeepAlive
keepAliveCancel context.CancelFunc
ServerID int64 `json:"ServerID,omitempty"`
ServerName string `json:"ServerName,omitempty"`
Address string `json:"Address,omitempty"`
Exclusive bool `json:"Exclusive,omitempty"`
Stopping bool `json:"Stopping,omitempty"`
TriggerKill bool
Version semver.Version `json:"Version,omitempty"`
liveCh <-chan bool
etcdCli *clientv3.Client
leaseID *clientv3.LeaseID
metaRoot string
registered atomic.Value
isStandby atomic.Value
enableActiveStandBy bool
activeKey string
useCustomConfig bool
sessionTTL int64
sessionRetryTimes int64
reuseNodeID bool
}
type SessionOption func(session *Session)
func WithCustomConfigEnable() SessionOption {
return func(session *Session) { session.useCustomConfig = true }
}
func WithTTL(ttl int64) SessionOption {
return func(session *Session) { session.sessionTTL = ttl }
}
func WithRetryTimes(n int64) SessionOption {
return func(session *Session) { session.sessionRetryTimes = n }
}
func WithResueNodeID(b bool) SessionOption {
return func(session *Session) { session.reuseNodeID = b }
}
func (s *Session) apply(opts ...SessionOption) {
for _, opt := range opts {
opt(s)
}
}
// UnmarshalJSON unmarshal bytes to Session.
func (s *Session) UnmarshalJSON(data []byte) error {
var raw struct {
ServerID int64 `json:"ServerID,omitempty"`
ServerName string `json:"ServerName,omitempty"`
Address string `json:"Address,omitempty"`
Exclusive bool `json:"Exclusive,omitempty"`
Stopping bool `json:"Stopping,omitempty"`
TriggerKill bool
Version string `json:"Version"`
}
err := json.Unmarshal(data, &raw)
if err != nil {
return err
}
if raw.Version != "" {
s.Version, err = semver.Parse(raw.Version)
if err != nil {
return err
}
}
s.ServerID = raw.ServerID
s.ServerName = raw.ServerName
s.Address = raw.Address
s.Exclusive = raw.Exclusive
s.Stopping = raw.Stopping
s.TriggerKill = raw.TriggerKill
return nil
}
// MarshalJSON marshals session to bytes.
func (s *Session) MarshalJSON() ([]byte, error) {
verStr := s.Version.String()
return json.Marshal(&struct {
ServerID int64 `json:"ServerID,omitempty"`
ServerName string `json:"ServerName,omitempty"`
Address string `json:"Address,omitempty"`
Exclusive bool `json:"Exclusive,omitempty"`
Stopping bool `json:"Stopping,omitempty"`
TriggerKill bool
Version string `json:"Version"`
}{
ServerID: s.ServerID,
ServerName: s.ServerName,
Address: s.Address,
Exclusive: s.Exclusive,
Stopping: s.Stopping,
TriggerKill: s.TriggerKill,
Version: verStr,
})
}
// NewSession is a helper to build Session object.
// ServerID, ServerName, Address, Exclusive will be assigned after Init().
// metaRoot is a path in etcd to save session information.
// etcdEndpoints is to init etcdCli when NewSession
func NewSession(ctx context.Context, metaRoot string, client *clientv3.Client, opts ...SessionOption) *Session {
session := &Session{
ctx: ctx,
metaRoot: metaRoot,
Version: common.Version,
// options
useCustomConfig: false,
sessionTTL: 60,
sessionRetryTimes: 30,
reuseNodeID: true,
}
session.apply(opts...)
session.UpdateRegistered(false)
connectEtcdFn := func() error {
log.Debug("Session try to connect to etcd")
ctx2, cancel2 := context.WithTimeout(session.ctx, 5*time.Second)
defer cancel2()
if _, err := client.Get(ctx2, "health"); err != nil {
return err
}
session.etcdCli = client
return nil
}
err := retry.Do(ctx, connectEtcdFn, retry.Attempts(100))
if err != nil {
log.Warn("failed to initialize session",
zap.Error(err))
return nil
}
log.Debug("Session connect to etcd success")
return session
}
// Init will initialize base struct of the Session, including ServerName, ServerID,
// Address, Exclusive. ServerID is obtained in getServerID.
func (s *Session) Init(serverName, address string, exclusive bool, triggerKill bool) {
s.ServerName = serverName
s.Address = address
s.Exclusive = exclusive
s.TriggerKill = triggerKill
s.checkIDExist()
serverID, err := s.getServerID()
if err != nil {
panic(err)
}
s.ServerID = serverID
log.Info("start server", zap.String("name", serverName), zap.String("address", address), zap.Int64("id", s.ServerID))
}
// String makes Session struct able to be logged by zap
func (s *Session) String() string {
return fmt.Sprintf("Session:<ServerID: %d, ServerName: %s, Version: %s>", s.ServerID, s.ServerName, s.Version.String())
}
// Register will process keepAliveResponse to keep alive with etcd.
func (s *Session) Register() {
ch, err := s.registerService()
if err != nil {
log.Error("Register failed", zap.Error(err))
panic(err)
}
s.liveCh = s.processKeepAliveResponse(ch)
s.UpdateRegistered(true)
}
var serverIDMu sync.Mutex
func (s *Session) getServerID() (int64, error) {
serverIDMu.Lock()
defer serverIDMu.Unlock()
log.Debug("getServerID", zap.Bool("reuse", s.reuseNodeID))
if s.reuseNodeID {
// Notice, For standalone, all process share the same nodeID.
if nodeID := paramtable.GetNodeID(); nodeID != 0 {
return nodeID, nil
}
}
nodeID, err := s.getServerIDWithKey(DefaultIDKey)
if err != nil {
return nodeID, err
}
if s.reuseNodeID {
paramtable.SetNodeID(nodeID)
}
return nodeID, nil
}
func (s *Session) checkIDExist() {
s.etcdCli.Txn(s.ctx).If(
clientv3.Compare(
clientv3.Version(path.Join(s.metaRoot, DefaultServiceRoot, DefaultIDKey)),
"=",
0)).
Then(clientv3.OpPut(path.Join(s.metaRoot, DefaultServiceRoot, DefaultIDKey), "1")).Commit()
}
func (s *Session) getServerIDWithKey(key string) (int64, error) {
for {
getResp, err := s.etcdCli.Get(s.ctx, path.Join(s.metaRoot, DefaultServiceRoot, key))
if err != nil {
log.Warn("Session get etcd key error", zap.String("key", key), zap.Error(err))
return -1, err
}
if getResp.Count <= 0 {
log.Warn("Session there is no value", zap.String("key", key))
continue
}
value := string(getResp.Kvs[0].Value)
valueInt, err := strconv.ParseInt(value, 10, 64)
if err != nil {
log.Warn("Session ParseInt error", zap.String("value", value), zap.Error(err))
continue
}
txnResp, err := s.etcdCli.Txn(s.ctx).If(
clientv3.Compare(
clientv3.Value(path.Join(s.metaRoot, DefaultServiceRoot, key)),
"=",
value)).
Then(clientv3.OpPut(path.Join(s.metaRoot, DefaultServiceRoot, key), strconv.FormatInt(valueInt+1, 10))).Commit()
if err != nil {
log.Warn("Session Txn failed", zap.String("key", key), zap.Error(err))
return -1, err
}
if !txnResp.Succeeded {
log.Warn("Session Txn unsuccessful", zap.String("key", key))
continue
}
log.Debug("Session get serverID success", zap.String("key", key), zap.Int64("ServerId", valueInt))
return valueInt, nil
}
}
func (s *Session) getCompleteKey() string {
key := s.ServerName
if !s.Exclusive || (s.enableActiveStandBy && s.isStandby.Load().(bool)) {
key = fmt.Sprintf("%s-%d", key, s.ServerID)
}
return path.Join(s.metaRoot, DefaultServiceRoot, key)
}
// registerService registers the service to etcd so that other services
// can find that the service is online and issue subsequent operations
// RegisterService will save a key-value in etcd
// key: metaRootPath + "/services" + "/ServerName-ServerID"
// value: json format
// {
// ServerID int64 `json:"ServerID,omitempty"`
// ServerName string `json:"ServerName,omitempty"`
// Address string `json:"Address,omitempty"`
// Exclusive bool `json:"Exclusive,omitempty"`
// }
// Exclusive means whether this service can exist two at the same time, if so,
// it is false. Otherwise, set it to true.
func (s *Session) registerService() (<-chan *clientv3.LeaseKeepAliveResponse, error) {
if s.enableActiveStandBy {
s.updateStandby(true)
}
completeKey := s.getCompleteKey()
var ch <-chan *clientv3.LeaseKeepAliveResponse
log.Debug("service begin to register to etcd", zap.String("serverName", s.ServerName), zap.Int64("ServerID", s.ServerID))
ttl := s.sessionTTL
retryTimes := s.sessionRetryTimes
if !s.useCustomConfig {
ttl = paramtable.Get().CommonCfg.SessionTTL.GetAsInt64()
retryTimes = paramtable.Get().CommonCfg.SessionRetryTimes.GetAsInt64()
}
registerFn := func() error {
resp, err := s.etcdCli.Grant(s.ctx, ttl)
if err != nil {
log.Error("register service", zap.Error(err))
return err
}
s.leaseID = &resp.ID
sessionJSON, err := json.Marshal(s)
if err != nil {
return err
}
txnResp, err := s.etcdCli.Txn(s.ctx).If(
clientv3.Compare(
clientv3.Version(completeKey),
"=",
0)).
Then(clientv3.OpPut(completeKey, string(sessionJSON), clientv3.WithLease(resp.ID))).Commit()
if err != nil {
log.Warn("compare and swap error, maybe the key has already been registered", zap.Error(err))
return err
}
if !txnResp.Succeeded {
return fmt.Errorf("function CompareAndSwap error for compare is false for key: %s", s.ServerName)
}
log.Debug("put session key into etcd", zap.String("key", completeKey), zap.String("value", string(sessionJSON)))
keepAliveCtx, keepAliveCancel := context.WithCancel(context.Background())
s.keepAliveCancel = func() {
// delete the session key to make roll update faster
// ignore the resp and error handle, just delete
_, _ = s.etcdCli.Delete(keepAliveCtx, completeKey)
if s.enableActiveStandBy && !s.isStandby.Load().(bool) {
_, _ = s.etcdCli.Delete(keepAliveCtx, s.activeKey)
}
keepAliveCancel()
}
ch, err = s.etcdCli.KeepAlive(keepAliveCtx, resp.ID)
if err != nil {
fmt.Printf("got error during keeping alive with etcd, err: %s\n", err)
return err
}
log.Info("Service registered successfully", zap.String("ServerName", s.ServerName), zap.Int64("serverID", s.ServerID))
return nil
}
err := retry.Do(s.ctx, registerFn, retry.Attempts(uint(retryTimes)))
if err != nil {
return nil, err
}
return ch, nil
}
// processKeepAliveResponse processes the response of etcd keepAlive interface
// If keepAlive fails for unexpected error, it will send a signal to the channel.
func (s *Session) processKeepAliveResponse(ch <-chan *clientv3.LeaseKeepAliveResponse) (failChannel <-chan bool) {
failCh := make(chan bool)
go func() {
for {
select {
case <-s.ctx.Done():
log.Warn("keep alive", zap.Error(errors.New("context done")))
if s.keepAliveCancel != nil {
s.keepAliveCancel()
}
return
case resp, ok := <-ch:
if !ok {
log.Warn("session keepalive channel closed")
close(failCh)
return
}
if resp == nil {
log.Warn("session keepalive response failed")
close(failCh)
return
}
//failCh <- true
}
}
}()
return failCh
}
// GetSessions will get all sessions registered in etcd.
// Revision is returned for WatchServices to prevent key events from being missed.
func (s *Session) GetSessions(prefix string) (map[string]*Session, int64, error) {
res := make(map[string]*Session)
key := path.Join(s.metaRoot, DefaultServiceRoot, prefix)
resp, err := s.etcdCli.Get(s.ctx, key, clientv3.WithPrefix(),
clientv3.WithSort(clientv3.SortByKey, clientv3.SortAscend))
if err != nil {
return nil, 0, err
}
for _, kv := range resp.Kvs {
session := &Session{}
err = json.Unmarshal(kv.Value, session)
if err != nil {
return nil, 0, err
}
_, mapKey := path.Split(string(kv.Key))
log.Debug("SessionUtil GetSessions ", zap.Any("prefix", prefix),
zap.String("key", mapKey),
zap.Any("address", session.Address))
res[mapKey] = session
}
return res, resp.Header.Revision, nil
}
// GetSessionsWithVersionRange will get all sessions with provided prefix and version range in etcd.
// Revision is returned for WatchServices to prevent missing events.
func (s *Session) GetSessionsWithVersionRange(prefix string, r semver.Range) (map[string]*Session, int64, error) {
res := make(map[string]*Session)
key := path.Join(s.metaRoot, DefaultServiceRoot, prefix)
resp, err := s.etcdCli.Get(s.ctx, key, clientv3.WithPrefix(),
clientv3.WithSort(clientv3.SortByKey, clientv3.SortAscend))
if err != nil {
return nil, 0, err
}
for _, kv := range resp.Kvs {
session := &Session{}
err = json.Unmarshal(kv.Value, session)
if err != nil {
return nil, 0, err
}
if !r(session.Version) {
log.Debug("Session version out of range", zap.String("version", session.Version.String()), zap.Int64("serverID", session.ServerID))
continue
}
_, mapKey := path.Split(string(kv.Key))
log.Debug("SessionUtil GetSessions ", zap.String("prefix", prefix),
zap.String("key", mapKey),
zap.String("address", session.Address))
res[mapKey] = session
}
return res, resp.Header.Revision, nil
}
func (s *Session) GoingStop() error {
if s == nil || s.etcdCli == nil || s.leaseID == nil {
return errors.New("the session hasn't been init")
}
completeKey := s.getCompleteKey()
resp, err := s.etcdCli.Get(s.ctx, completeKey, clientv3.WithCountOnly())
if err != nil {
log.Error("fail to get the session", zap.String("key", completeKey), zap.Error(err))
return err
}
if resp.Count == 0 {
return nil
}
s.Stopping = true
sessionJSON, err := json.Marshal(s)
if err != nil {
log.Error("fail to marshal the session", zap.String("key", completeKey))
return err
}
_, err = s.etcdCli.Put(s.ctx, completeKey, string(sessionJSON), clientv3.WithLease(*s.leaseID))
if err != nil {
log.Error("fail to update the session to stopping state", zap.String("key", completeKey))
return err
}
return nil
}
// SessionEvent indicates the changes of other servers.
// if a server is up, EventType is SessAddEvent.
// if a server is down, EventType is SessDelEvent.
// Session Saves the changed server's information.
type SessionEvent struct {
EventType SessionEventType
Session *Session
}
type sessionWatcher struct {
s *Session
rch clientv3.WatchChan
eventCh chan *SessionEvent
prefix string
rewatch Rewatch
validate func(*Session) bool
}
func (w *sessionWatcher) start() {
go func() {
for {
select {
case <-w.s.ctx.Done():
return
case wresp, ok := <-w.rch:
if !ok {
log.Warn("session watch channel closed")
return
}
w.handleWatchResponse(wresp)
}
}
}()
}
// WatchServices watches the service's up and down in etcd, and sends event to
// eventChannel.
// prefix is a parameter to know which service to watch and can be obtained in
// typeutil.type.go.
// revision is a etcd reversion to prevent missing key events and can be obtained
// in GetSessions.
// If a server up, an event will be add to channel with eventType SessionAddType.
// If a server down, an event will be add to channel with eventType SessionDelType.
func (s *Session) WatchServices(prefix string, revision int64, rewatch Rewatch) (eventChannel <-chan *SessionEvent) {
w := &sessionWatcher{
s: s,
eventCh: make(chan *SessionEvent, 100),
rch: s.etcdCli.Watch(s.ctx, path.Join(s.metaRoot, DefaultServiceRoot, prefix), clientv3.WithPrefix(), clientv3.WithPrevKV(), clientv3.WithRev(revision)),
prefix: prefix,
rewatch: rewatch,
validate: func(s *Session) bool { return true },
}
w.start()
return w.eventCh
}
// WatchServicesWithVersionRange watches the service's up and down in etcd, and sends event to event Channel.
// Acts like WatchServices but with extra version range check.
// prefix is a parameter to know which service to watch and can be obtained in type util.type.go.
// revision is a etcd reversion to prevent missing key events and can be obtained in GetSessions.
// If a server up, an event will be add to channel with eventType SessionAddType.
// If a server down, an event will be add to channel with eventType SessionDelType.
func (s *Session) WatchServicesWithVersionRange(prefix string, r semver.Range, revision int64, rewatch Rewatch) (eventChannel <-chan *SessionEvent) {
w := &sessionWatcher{
s: s,
eventCh: make(chan *SessionEvent, 100),
rch: s.etcdCli.Watch(s.ctx, path.Join(s.metaRoot, DefaultServiceRoot, prefix), clientv3.WithPrefix(), clientv3.WithPrevKV(), clientv3.WithRev(revision)),
prefix: prefix,
rewatch: rewatch,
validate: func(s *Session) bool { return r(s.Version) },
}
w.start()
return w.eventCh
}
func (w *sessionWatcher) handleWatchResponse(wresp clientv3.WatchResponse) {
if wresp.Err() != nil {
err := w.handleWatchErr(wresp.Err())
if err != nil {
log.Error("failed to handle watch session response", zap.Error(err))
panic(err)
}
return
}
for _, ev := range wresp.Events {
session := &Session{}
var eventType SessionEventType
switch ev.Type {
case mvccpb.PUT:
log.Debug("watch services",
zap.Any("add kv", ev.Kv))
err := json.Unmarshal([]byte(ev.Kv.Value), session)
if err != nil {
log.Error("watch services", zap.Error(err))
continue
}
if !w.validate(session) {
continue
}
if session.Stopping {
eventType = SessionUpdateEvent
} else {
eventType = SessionAddEvent
}
case mvccpb.DELETE:
log.Debug("watch services",
zap.Any("delete kv", ev.PrevKv))
err := json.Unmarshal([]byte(ev.PrevKv.Value), session)
if err != nil {
log.Error("watch services", zap.Error(err))
continue
}
if !w.validate(session) {
continue
}
eventType = SessionDelEvent
}
log.Debug("WatchService", zap.Any("event type", eventType))
w.eventCh <- &SessionEvent{
EventType: eventType,
Session: session,
}
}
}
func (w *sessionWatcher) handleWatchErr(err error) error {
// if not ErrCompacted, just close the channel
if err != v3rpc.ErrCompacted {
//close event channel
log.Warn("Watch service found error", zap.Error(err))
close(w.eventCh)
return err
}
sessions, revision, err := w.s.GetSessions(w.prefix)
if err != nil {
log.Warn("GetSession before rewatch failed", zap.String("prefix", w.prefix), zap.Error(err))
close(w.eventCh)
return err
}
// rewatch is nil, no logic to handle
if w.rewatch == nil {
log.Warn("Watch service with ErrCompacted but no rewatch logic provided")
} else {
err = w.rewatch(sessions)
}
if err != nil {
log.Warn("WatchServices rewatch failed", zap.String("prefix", w.prefix), zap.Error(err))
close(w.eventCh)
return err
}
w.rch = w.s.etcdCli.Watch(w.s.ctx, path.Join(w.s.metaRoot, DefaultServiceRoot, w.prefix), clientv3.WithPrefix(), clientv3.WithPrevKV(), clientv3.WithRev(revision))
return nil
}
// LivenessCheck performs liveness check with provided context and channel
// ctx controls the liveness check loop
// ch is the liveness signal channel, ch is closed only when the session is expired
// callback is the function to call when ch is closed, note that callback will not be invoked when loop exits due to context
func (s *Session) LivenessCheck(ctx context.Context, callback func()) {
for {
select {
case _, ok := <-s.liveCh:
// ok, still alive
if ok {
continue
}
// not ok, connection lost
log.Warn("connection lost detected, shuting down")
if callback != nil {
go callback()
}
return
case <-ctx.Done():
log.Debug("liveness exits due to context done")
// cancel the etcd keepAlive context
if s.keepAliveCancel != nil {
s.keepAliveCancel()
}
return
}
}
}
// Revoke revokes the internal leaseID for the session key
func (s *Session) Revoke(timeout time.Duration) {
if s == nil {
return
}
if s.etcdCli == nil || s.leaseID == nil {
return
}
// can NOT use s.ctx, it may be Done here
ctx, cancel := context.WithTimeout(context.Background(), timeout)
defer cancel()
// ignores resp & error, just do best effort to revoke
_, _ = s.etcdCli.Revoke(ctx, *s.leaseID)
}
// UpdateRegistered update the state of registered.
func (s *Session) UpdateRegistered(b bool) {
s.registered.Store(b)
}
// Registered check if session was registered into etcd.
func (s *Session) Registered() bool {
b, ok := s.registered.Load().(bool)
if !ok {
return false
}
return b
}
func (s *Session) SetEnableActiveStandBy(enable bool) {
s.enableActiveStandBy = enable
}
func (s *Session) updateStandby(b bool) {
s.isStandby.Store(b)
}
// ProcessActiveStandBy is used by coordinators to do active-standby mechanism.
// coordinator enabled active-standby will first call Register and then call ProcessActiveStandBy.
// steps:
// 1, Enter STANDBY mode
// 2, Try to register to active key.
// 3, If 2. return true, this service becomes ACTIVE. Exit STANDBY mode.
// 4, If 2. return false, which means an ACTIVE service already exist.
// Start watching the active key. Whenever active key disappears, STANDBY node will go backup to 2.
// activateFunc is the function to re-active the service.
func (s *Session) ProcessActiveStandBy(activateFunc func()) error {
s.activeKey = path.Join(s.metaRoot, DefaultServiceRoot, s.ServerName)
// try to register to the active_key.
// return
// 1. doRegistered: if registered the active_key by this session or by other session
// 2. revision: revision of the active_key
// 3. err: etcd error, should retry
registerActiveFn := func() (bool, int64, error) {
log.Info(fmt.Sprintf("try to register as ACTIVE %v service...", s.ServerName))
sessionJSON, err := json.Marshal(s)
if err != nil {
log.Error("json marshal error", zap.Error(err))
return false, -1, err
}
txnResp, err := s.etcdCli.Txn(s.ctx).If(
clientv3.Compare(
clientv3.Version(s.activeKey),
"=",
0)).
Then(clientv3.OpPut(s.activeKey, string(sessionJSON), clientv3.WithLease(*s.leaseID))).Commit()
if err != nil {
log.Error("register active key to etcd failed", zap.Error(err))
return false, -1, err
}
doRegistered := txnResp.Succeeded
if doRegistered {
log.Info(fmt.Sprintf("register ACTIVE %s", s.ServerName))
} else {
log.Info(fmt.Sprintf("ACTIVE %s has already been registered", s.ServerName))
}
revision := txnResp.Header.GetRevision()
return doRegistered, revision, nil
}
s.updateStandby(true)
log.Info(fmt.Sprintf("serverName: %v enter STANDBY mode", s.ServerName))
go func() {
for s.isStandby.Load().(bool) {
log.Debug(fmt.Sprintf("serverName: %v is in STANDBY ...", s.ServerName))
time.Sleep(10 * time.Second)
}
}()
for {
registered, revision, err := registerActiveFn()
if err != nil {
time.Sleep(100 * time.Millisecond)
continue
}
if registered {
break
}
log.Info(fmt.Sprintf("%s start to watch ACTIVE key", s.ServerName))
ctx, cancel := context.WithCancel(s.ctx)
watchChan := s.etcdCli.Watch(ctx, s.activeKey, clientv3.WithPrefix(), clientv3.WithPrevKV(), clientv3.WithRev(revision))
select {
case <-ctx.Done():
cancel()
case wresp, ok := <-watchChan:
if !ok {
cancel()
}
if wresp.Err() != nil {
cancel()
}
for _, event := range wresp.Events {
switch event.Type {
case mvccpb.PUT:
log.Debug("watch the ACTIVE key", zap.Any("ADD", event.Kv))
case mvccpb.DELETE:
log.Debug("watch the ACTIVE key", zap.Any("DELETE", event.Kv))
cancel()
}
}
}
cancel()
log.Info(fmt.Sprintf("stop watching ACTIVE key %v", s.activeKey))
}
s.updateStandby(false)
log.Info(fmt.Sprintf("serverName: %v quit STANDBY mode, this node will become ACTIVE", s.ServerName))
if activateFunc != nil {
activateFunc()
}
return nil
}