Exemple #1
0
// handleMaster performs one loop of master locking.
// on success it returns <master>, nil
// on error it returns "", err
// in situations where you should try again due to concurrent state changes (e.g. another actor simultaneously acquiring the lock)
// it returns "", nil
func (e *etcdMasterElector) handleMaster(path, id string, ttl uint64) (string, error) {
	res, err := e.etcd.Get(path, false, false)

	// Unexpected error, bail out
	if err != nil && !etcdstorage.IsEtcdNotFound(err) {
		return "", err
	}

	// There is no master, try to become the master.
	if err != nil && etcdstorage.IsEtcdNotFound(err) {
		return e.becomeMaster(path, id, ttl)
	}

	// This should never happen.
	if res.Node == nil {
		return "", fmt.Errorf("unexpected response: %#v", res)
	}

	// We're not the master, just return the current value
	if res.Node.Value != id {
		return res.Node.Value, nil
	}

	// We are the master, try to extend out lease
	return e.extendMaster(path, id, ttl, res)
}
Exemple #2
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// acquireOrRenewLease either races to acquire a new master lease, or update the existing master's lease
// returns true if we have the lease, and an error if one occurs.
// TODO: use the master election utility once it is merged in.
func (c *config) acquireOrRenewLease(etcdClient *etcd.Client) (bool, error) {
	result, err := etcdClient.Get(c.key, false, false)
	if err != nil {
		if etcdstorage.IsEtcdNotFound(err) {
			// there is no current master, try to become master, create will fail if the key already exists
			_, err := etcdClient.Create(c.key, c.whoami, c.ttl)
			if err != nil {
				return false, err
			}
			c.lastLease = time.Now()
			return true, nil
		}
		return false, err
	}
	if result.Node.Value == c.whoami {
		glog.Infof("key already exists, we are the master (%s)", result.Node.Value)
		// we extend our lease @ 1/2 of the existing TTL, this ensures the master doesn't flap around
		if result.Node.Expiration.Sub(time.Now()) < time.Duration(c.ttl/2)*time.Second {
			_, err := etcdClient.CompareAndSwap(c.key, c.whoami, c.ttl, c.whoami, result.Node.ModifiedIndex)
			if err != nil {
				return false, err
			}
		}
		c.lastLease = time.Now()
		return true, nil
	}
	glog.Infof("key already exists, the master is %s, sleeping.", result.Node.Value)
	return false, nil
}
Exemple #3
0
// InterpretDeleteError converts a generic etcd error on a delete
// operation into the appropriate API error.
func InterpretDeleteError(err error, kind, name string) error {
	switch {
	case etcdstorage.IsEtcdNotFound(err):
		return errors.NewNotFound(kind, name)
	default:
		return err
	}
}
Exemple #4
0
func (s *SchedulerServer) fetchFrameworkID(client tools.EtcdClient) (*mesos.FrameworkID, error) {
	if s.FailoverTimeout > 0 {
		if response, err := client.Get(meta.FrameworkIDKey, false, false); err != nil {
			if !etcdstorage.IsEtcdNotFound(err) {
				return nil, fmt.Errorf("unexpected failure attempting to load framework ID from etcd: %v", err)
			}
			log.V(1).Infof("did not find framework ID in etcd")
		} else if response.Node.Value != "" {
			log.Infof("configuring FrameworkInfo with Id found in etcd: '%s'", response.Node.Value)
			return mutil.NewFrameworkID(response.Node.Value), nil
		}
	} else {
		//TODO(jdef) this seems like a totally hackish way to clean up the framework ID
		if _, err := client.Delete(meta.FrameworkIDKey, true); err != nil {
			if !etcdstorage.IsEtcdNotFound(err) {
				return nil, fmt.Errorf("failed to delete framework ID from etcd: %v", err)
			}
			log.V(1).Infof("nothing to delete: did not find framework ID in etcd")
		}
	}
	return nil, nil
}
Exemple #5
0
// Refresh reloads the RangeAllocation from etcd.
func (e *Etcd) Refresh() (*api.RangeAllocation, error) {
	e.lock.Lock()
	defer e.lock.Unlock()

	existing := &api.RangeAllocation{}
	if err := e.storage.Get(e.baseKey, existing, false); err != nil {
		if etcdstorage.IsEtcdNotFound(err) {
			return nil, nil
		}
		return nil, etcderr.InterpretGetError(err, e.kind, "")
	}

	return existing, nil
}