Method Lock

sync/etcd/etcd.go:127–161

Lock locks resources on sync This call blocks until you can get lock

(path string, block bool)

// Lock locks resources on sync
// This call blocks until you can get lock
func (s *Sync) Lock(path string, block bool) (chan struct{}, error) {
	for {
		_, err := s.etcdClient.Create(path, s.processID, masterTTL)
		if err != nil {
			log.Notice("failed to lock path %s: %s", path, err)
			s.locks.Set(path, false)
			if !block {
				return nil, err
			}
			time.Sleep(masterTTL * time.Second)
			continue
		}
		s.locks.Set(path, true)
		log.Info("Locked %s", path)

		//Refresh master token
		lost := make(chan struct{})
		go func() {
			defer s.abortLock(path)
			defer close(lost)

			for s.HasLock(path) {
				_, err := s.etcdClient.CompareAndSwap(
					path, s.processID, masterTTL, s.processID, 0)
				if err != nil {
					log.Notice("failed to keepalive lock for %s %s", path, err)
					s.locks.Set(path, false)
					return
				}
				time.Sleep(masterTTL / 2 * time.Second)
			}
		}()
		return lost, nil
	}
}

func (s *Sync) abortLock(path string) {
	s.locks.Set(path, false)