Пример #1
0
func rpcAcquireLeadership(reg registry.Registry, lManager lease.Manager, machID string, ver int, ttl time.Duration) lease.Lease {
	existing, err := lManager.GetLease(engineLeaseName)
	if err != nil {
		log.Errorf("Unable to determine current lease: %v", err)
		return nil
	}

	var l lease.Lease
	if (existing == nil && reg.UseEtcdRegistry()) || (existing == nil && !reg.IsRegistryReady()) {
		l, err = lManager.AcquireLease(engineLeaseName, machID, ver, ttl)
		if err != nil {
			log.Errorf("Engine leadership acquisition failed: %v", err)
			return nil
		} else if l == nil {
			log.Infof("Unable to acquire engine leadership")
			return nil
		}
		log.Infof("Engine leadership acquired")
		return l
	}

	if existing != nil && existing.Version() >= ver {
		log.Debugf("Lease already held by Machine(%s) operating at acceptable version %d", existing.MachineID(), existing.Version())
		return existing
	}

	// TODO(hector): Here we could add a possible SLA to determine when the leader
	// is too busy. In such a case, we can trigger a new leader election
	if (existing != nil && reg.UseEtcdRegistry()) || (existing != nil && !reg.IsRegistryReady()) {
		rem := existing.TimeRemaining()
		l, err = lManager.StealLease(engineLeaseName, machID, ver, ttl+rem, existing.Index())
		if err != nil {
			log.Errorf("Engine leadership steal failed: %v", err)
			return nil
		} else if l == nil {
			log.Infof("Unable to steal engine leadership")
			return nil
		}

		log.Infof("Stole engine leadership from Machine(%s)", existing.MachineID())

		if rem > 0 {
			log.Infof("Waiting %v for previous lease to expire before continuing reconciliation", rem)
			<-time.After(rem)
		}

		return l
	}

	log.Infof("Engine leader is BUSY!")

	return existing

}
Пример #2
0
func acquireLeadership(lManager lease.Manager, machID string, ver int, ttl time.Duration) lease.Lease {
	existing, err := lManager.GetLease(engineLeaseName)
	if err != nil {
		log.Errorf("Unable to determine current lease: %v", err)
		return nil
	}

	var l lease.Lease
	if existing == nil {
		l, err = lManager.AcquireLease(engineLeaseName, machID, ver, ttl)
		if err != nil {
			log.Errorf("Engine leadership acquisition failed: %v", err)
			return nil
		} else if l == nil {
			log.Debugf("Unable to acquire engine leadership")
			return nil
		}
		log.Infof("Engine leadership acquired")
		metrics.ReportEngineLeader()
		return l
	}

	if existing.Version() >= ver {
		log.Debugf("Lease already held by Machine(%s) operating at acceptable version %d", existing.MachineID(), existing.Version())
		return existing
	}

	rem := existing.TimeRemaining()
	l, err = lManager.StealLease(engineLeaseName, machID, ver, ttl+rem, existing.Index())
	if err != nil {
		log.Errorf("Engine leadership steal failed: %v", err)
		return nil
	} else if l == nil {
		log.Debugf("Unable to steal engine leadership")
		return nil
	}

	log.Infof("Stole engine leadership from Machine(%s)", existing.MachineID())
	metrics.ReportEngineLeader()

	if rem > 0 {
		log.Infof("Waiting %v for previous lease to expire before continuing reconciliation", rem)
		<-time.After(rem)
	}

	return l
}