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128 lines
3.1 KiB
128 lines
3.1 KiB
package lock_manager
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import (
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"fmt"
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"github.com/google/uuid"
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"github.com/puzpuzpuz/xsync/v2"
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"time"
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)
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// LockManager lock manager
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type LockManager struct {
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locks *xsync.MapOf[string, *Lock]
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}
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type Lock struct {
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Token string
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ExpiredAtNs int64
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Key string // only used for moving locks
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}
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func NewLockManager() *LockManager {
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t := &LockManager{
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locks: xsync.NewMapOf[*Lock](),
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}
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go t.CleanUp()
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return t
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}
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func (lm *LockManager) Lock(path string, expiredAtNs int64, token string) (renewToken string, err error) {
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lm.locks.Compute(path, func(oldValue *Lock, loaded bool) (newValue *Lock, delete bool) {
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if oldValue != nil {
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if oldValue.ExpiredAtNs > 0 && oldValue.ExpiredAtNs < time.Now().UnixNano() {
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// lock is expired, set to a new lock
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if token != "" {
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err = fmt.Errorf("lock: non-empty token on an expired lock")
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return nil, false
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} else {
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// new lock
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renewToken = uuid.New().String()
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return &Lock{Token: renewToken, ExpiredAtNs: expiredAtNs}, false
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}
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}
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// not expired
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if oldValue.Token == token {
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// token matches, renew the lock
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return &Lock{Token: token, ExpiredAtNs: expiredAtNs}, false
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} else {
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err = fmt.Errorf("lock: token mismatch")
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return oldValue, false
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}
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} else {
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if token == "" {
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// new lock
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renewToken = uuid.New().String()
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return &Lock{Token: renewToken, ExpiredAtNs: expiredAtNs}, false
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} else {
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err = fmt.Errorf("lock: non-empty token on a new lock")
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return nil, false
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}
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}
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})
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return
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}
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func (lm *LockManager) Unlock(path string, token string) (isUnlocked bool, err error) {
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lm.locks.Compute(path, func(oldValue *Lock, loaded bool) (newValue *Lock, delete bool) {
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if oldValue != nil {
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now := time.Now()
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if oldValue.ExpiredAtNs > 0 && oldValue.ExpiredAtNs < now.UnixNano() {
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// lock is expired, delete it
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isUnlocked = true
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return nil, true
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}
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if oldValue.Token == token {
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if oldValue.ExpiredAtNs <= now.UnixNano() {
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isUnlocked = true
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return nil, true
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}
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return oldValue, false
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} else {
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isUnlocked = false
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err = fmt.Errorf("unlock: token mismatch")
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return oldValue, false
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}
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} else {
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isUnlocked = true
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return nil, true
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}
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})
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return
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}
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func (lm *LockManager) CleanUp() {
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for {
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time.Sleep(1 * time.Minute)
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now := time.Now().UnixNano()
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lm.locks.Range(func(key string, value *Lock) bool {
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if now > value.ExpiredAtNs {
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lm.locks.Delete(key)
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return true
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}
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return true
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})
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}
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}
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// SelectLocks takes out locks by key
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// if keyFn return true, the lock will be taken out
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func (lm *LockManager) SelectLocks(selectFn func(key string) bool) (locks []*Lock) {
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now := time.Now().UnixNano()
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lm.locks.Range(func(key string, lock *Lock) bool {
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if now > lock.ExpiredAtNs {
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lm.locks.Delete(key)
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return true
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}
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if selectFn(key) {
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lm.locks.Delete(key)
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lock.Key = key
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locks = append(locks, lock)
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}
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return true
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})
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return
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}
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// InsertLock inserts a lock unconditionally
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func (lm *LockManager) InsertLock(path string, expiredAtNs int64, token string) {
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lm.locks.Store(path, &Lock{Token: token, ExpiredAtNs: expiredAtNs})
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}
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