feat: 优化领导者服务

This commit is contained in:
tbphp
2025-07-08 21:10:06 +08:00
parent 7340cdded1
commit fe3fd9c14a
4 changed files with 90 additions and 34 deletions

View File

@@ -55,6 +55,10 @@ func (s *KeyCronService) Stop() {
func (s *KeyCronService) runLoop() {
defer s.wg.Done()
if s.LeaderService.IsLeader() {
s.submitValidationJobs()
}
ticker := time.NewTicker(5 * time.Minute)
defer ticker.Stop()

View File

@@ -16,9 +16,26 @@ const (
leaderLockKey = "cluster:leader"
leaderLockTTL = 30 * time.Second
leaderRenewalInterval = 10 * time.Second
leaderElectionTimeout = 5 * time.Second
)
// Lua script for atomic lock renewal.
// KEYS[1]: lock key, ARGV[1]: node ID, ARGV[2]: TTL in seconds.
const renewLockScript = `
if redis.call("get", KEYS[1]) == ARGV[1] then
return redis.call("expire", KEYS[1], ARGV[2])
else
return 0
end`
// Lua script for atomic lock release.
// KEYS[1]: lock key, ARGV[1]: node ID.
const releaseLockScript = `
if redis.call("get", KEYS[1]) == ARGV[1] then
return redis.call("del", KEYS[1])
else
return 0
end`
// LeaderService provides a mechanism for electing a single leader in a cluster.
type LeaderService struct {
store store.Store
@@ -26,40 +43,63 @@ type LeaderService struct {
isLeader atomic.Bool
stopChan chan struct{}
wg sync.WaitGroup
isSingleNode bool
firstElectionDone chan struct{}
firstElectionOnce sync.Once
}
// NewLeaderService creates a new LeaderService.
func NewLeaderService(store store.Store) *LeaderService {
return &LeaderService{
store: store,
func NewLeaderService(s store.Store) *LeaderService {
// Check if the store supports Lua scripting to determine if we are in a distributed environment.
_, isDistributed := s.(store.LuaScripter)
service := &LeaderService{
store: s,
nodeID: generateNodeID(),
stopChan: make(chan struct{}),
isSingleNode: !isDistributed,
firstElectionDone: make(chan struct{}),
}
if service.isSingleNode {
logrus.Info("Store does not support Lua, running in single-node mode. Assuming leadership.")
service.isLeader.Store(true)
close(service.firstElectionDone)
} else {
logrus.Info("Store supports Lua, running in distributed mode.")
}
return service
}
// Start begins the leader election process.
func (s *LeaderService) Start() {
logrus.WithField("nodeID", s.nodeID).Info("Starting LeaderService...")
if s.isSingleNode {
return
}
s.wg.Add(1)
go s.electionLoop()
}
// Stop gracefully stops the leader election process.
func (s *LeaderService) Stop() {
logrus.Info("Stopping LeaderService...")
if s.isSingleNode {
return
}
close(s.stopChan)
s.wg.Wait()
logrus.Info("LeaderService stopped.")
}
// IsLeader returns true if the current node is the leader.
// This is a fast, local check against an atomic boolean.
// In distributed mode, this call will block until the first election attempt is complete.
func (s *LeaderService) IsLeader() bool {
<-s.firstElectionDone
return s.isLeader.Load()
}
func (s *LeaderService) electionLoop() {
defer s.wg.Done()
logrus.WithField("nodeID", s.nodeID).Info("Starting leader election loop...")
// Attempt to acquire leadership immediately on start.
s.tryToBeLeader()
@@ -72,7 +112,8 @@ func (s *LeaderService) electionLoop() {
case <-ticker.C:
s.tryToBeLeader()
case <-s.stopChan:
if s.IsLeader() {
logrus.Info("Stopping leader election loop...")
if s.isLeader.Load() {
s.releaseLock()
}
return
@@ -81,8 +122,11 @@ func (s *LeaderService) electionLoop() {
}
func (s *LeaderService) tryToBeLeader() {
if s.IsLeader() {
// Already the leader, just renew the lock.
defer s.firstElectionOnce.Do(func() {
close(s.firstElectionDone)
})
if s.isLeader.Load() {
if err := s.renewLock(); err != nil {
logrus.WithError(err).Error("Failed to renew leader lock, relinquishing leadership.")
s.isLeader.Store(false)
@@ -90,7 +134,6 @@ func (s *LeaderService) tryToBeLeader() {
return
}
// Not the leader, try to acquire the lock.
acquired, err := s.acquireLock()
if err != nil {
logrus.WithError(err).Error("Error trying to acquire leader lock.")
@@ -101,41 +144,40 @@ func (s *LeaderService) tryToBeLeader() {
if acquired {
logrus.WithField("nodeID", s.nodeID).Info("Successfully acquired leader lock.")
s.isLeader.Store(true)
} else {
logrus.Debug("Could not acquire leader lock, another node is likely the leader.")
s.isLeader.Store(false)
}
}
func (s *LeaderService) acquireLock() (bool, error) {
// SetNX is an atomic operation. If the key already exists, it does nothing.
// This is the core of our distributed lock.
return s.store.SetNX(leaderLockKey, []byte(s.nodeID), leaderLockTTL)
}
func (s *LeaderService) renewLock() error {
// To renew, we must ensure we are still the lock holder.
// A LUA script is the safest way to do this atomically.
// For simplicity here, we get and set, but this is not truly atomic without LUA.
// A simple SET can also work if we are confident in our election loop timing.
return s.store.Set(leaderLockKey, []byte(s.nodeID), leaderLockTTL)
luaStore := s.store.(store.LuaScripter) // Already checked in NewLeaderService
ttlSeconds := int(leaderLockTTL.Seconds())
res, err := luaStore.Eval(renewLockScript, []string{leaderLockKey}, s.nodeID, ttlSeconds)
if err != nil {
return err
}
if i, ok := res.(int64); !ok || i == 0 {
return store.ErrNotFound // Not our lock anymore
}
return nil
}
func (s *LeaderService) releaseLock() {
// Best-effort attempt to release the lock on shutdown.
// The TTL will handle cases where this fails.
if err := s.store.Delete(leaderLockKey); err != nil {
luaStore := s.store.(store.LuaScripter) // Already checked in NewLeaderService
if _, err := luaStore.Eval(releaseLockScript, []string{leaderLockKey}, s.nodeID); err != nil {
logrus.WithError(err).Error("Failed to release leader lock on shutdown.")
} else {
logrus.Info("Successfully released leader lock.")
}
s.isLeader.Store(false)
}
func generateNodeID() string {
bytes := make([]byte, 16)
if _, err := rand.Read(bytes); err != nil {
// Fallback to a timestamp-based ID if crypto/rand fails
return "node-" + time.Now().Format(time.RFC3339Nano)
}
return hex.EncodeToString(bytes)

View File

@@ -117,3 +117,8 @@ func (s *RedisStore) Pipeline() Pipeliner {
pipe: s.client.Pipeline(),
}
}
// Eval executes a Lua script on Redis.
func (s *RedisStore) Eval(script string, keys []string, args ...interface{}) (interface{}, error) {
return s.client.Eval(context.Background(), script, keys, args...).Result()
}

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@@ -56,3 +56,8 @@ type Pipeliner interface {
type RedisPipeliner interface {
Pipeline() Pipeliner
}
// LuaScripter is an optional interface that a Store can implement to provide Lua script execution.
type LuaScripter interface {
Eval(script string, keys []string, args ...interface{}) (interface{}, error)
}