Exemplo n.º 1
0
// extendMaster attempts to extend ownership of a master lock for TTL seconds.
// returns "", nil if extension failed
// returns id, nil if extension succeeded
// returns "", err if an error occurred
func (e *etcdMasterElector) extendMaster(path, id string, ttl uint64, res *etcd.Response) (string, error) {
	// If it matches the passed in id, extend the lease by writing a new entry.
	// Uses compare and swap, so that if we TTL out in the meantime, the write will fail.
	// We don't handle the TTL delete w/o a write case here, it's handled in the next loop
	// iteration.
	_, err := e.etcd.CompareAndSwap(path, id, ttl, "", res.Node.ModifiedIndex)
	if err != nil && !etcdstorage.IsEtcdTestFailed(err) {
		return "", err
	}
	if err != nil && etcdstorage.IsEtcdTestFailed(err) {
		return "", nil
	}
	return id, nil
}
Exemplo n.º 2
0
// InterpretUpdateError converts a generic etcd error on a update
// operation into the appropriate API error.
func InterpretUpdateError(err error, kind, name string) error {
	switch {
	case etcdstorage.IsEtcdTestFailed(err), etcdstorage.IsEtcdNodeExist(err):
		return errors.NewConflict(kind, name, err)
	default:
		return err
	}
}
Exemplo n.º 3
0
// InterpretUpdateError converts a generic etcd error on a update
// operation into the appropriate API error.
func InterpretUpdateError(err error, kind, name string) error {
	switch {
	case etcdstorage.IsEtcdTestFailed(err), etcdstorage.IsEtcdNodeExist(err):
		return errors.NewConflict(kind, name, err)
	case etcdstorage.IsEtcdUnreachable(err):
		return errors.NewServerTimeout(kind, "update", 2) // TODO: make configurable or handled at a higher level
	default:
		return err
	}
}
Exemplo n.º 4
0
// Release tries to delete the leader lock.
func (e *Etcd) Release() {
	for i := 0; i < e.maxRetries; i++ {
		_, err := e.client.CompareAndDelete(e.key, e.value, 0)
		if err == nil {
			break
		}
		// If the value has changed, we don't hold the lease. If the key is missing we don't
		// hold the lease.
		if storage.IsEtcdTestFailed(err) || storage.IsEtcdNotFound(err) {
			break
		}
		util.HandleError(fmt.Errorf("unable to release %s: %v", e.key, err))
	}
}
Exemplo n.º 5
0
// errToAPIStatus converts an error to an unversioned.Status object.
func errToAPIStatus(err error) *unversioned.Status {
	switch t := err.(type) {
	case statusError:
		status := t.Status()
		if len(status.Status) == 0 {
			status.Status = unversioned.StatusFailure
		}
		if status.Code == 0 {
			switch status.Status {
			case unversioned.StatusSuccess:
				status.Code = http.StatusOK
			case unversioned.StatusFailure:
				status.Code = http.StatusInternalServerError
			}
		}
		//TODO: check for invalid responses
		return &status
	default:
		status := http.StatusInternalServerError
		switch {
		//TODO: replace me with NewConflictErr
		case etcdstorage.IsEtcdTestFailed(err):
			status = http.StatusConflict
		}
		// Log errors that were not converted to an error status
		// by REST storage - these typically indicate programmer
		// error by not using pkg/api/errors, or unexpected failure
		// cases.
		util.HandleError(fmt.Errorf("apiserver received an error that is not an unversioned.Status: %v", err))
		return &unversioned.Status{
			Status:  unversioned.StatusFailure,
			Code:    status,
			Reason:  unversioned.StatusReasonUnknown,
			Message: err.Error(),
		}
	}
}
Exemplo n.º 6
0
// tryHold attempts to hold on to the lease by repeatedly refreshing its TTL.
// If the lease hold fails, is deleted, or changed to another user. The provided
// index is used to watch from.
// TODO: currently if we miss the watch window, we will error and try to recreate
//   the lock. It's likely we will lose the lease due to that.
func (e *Etcd) tryHold(ttl, index uint64) error {
	// watch for termination
	stop := make(chan struct{})
	lost := make(chan struct{})
	watchIndex := index
	go util.Until(func() {
		index, err := e.waitForExpiration(true, watchIndex, stop)
		watchIndex = index
		if err != nil {
			util.HandleError(fmt.Errorf("error watching for lease expiration %s: %v", e.key, err))
			return
		}
		glog.V(4).Infof("Lease %s lost due to deletion", e.key)
		close(lost)
	}, 100*time.Millisecond, stop)
	defer close(stop)

	duration := time.Duration(ttl) * time.Second
	after := time.Duration(float32(duration) * e.waitFraction)
	last := duration - after
	interval := last / time.Duration(e.maxRetries)
	if interval < e.minimumRetryInterval {
		interval = e.minimumRetryInterval
	}

	// as long as we can renew the lease, loop
	for {
		select {
		case <-time.After(after):
			err := wait.Poll(interval, last, func() (bool, error) {
				glog.V(4).Infof("Renewing lease %s", e.key)
				resp, err := e.client.CompareAndSwap(e.key, e.value, e.ttl, e.value, index-1)
				switch {
				case err == nil:
					index = eventIndexFor(resp)
					return true, nil
				case storage.IsEtcdTestFailed(err):
					return false, fmt.Errorf("another client has taken the lease %s: %v", e.key, err)
				case storage.IsEtcdNotFound(err):
					return false, fmt.Errorf("another client has revoked the lease %s", e.key)
				default:
					util.HandleError(fmt.Errorf("unexpected error renewing lease %s: %v", e.key, err))
					index = etcdIndexFor(err, index)
					// try again
					return false, nil
				}
			})

			switch err {
			case nil:
				// wait again
				glog.V(4).Infof("Lease %s renewed", e.key)
			case wait.ErrWaitTimeout:
				return fmt.Errorf("unable to renew lease %s: %v", e.key, err)
			default:
				return fmt.Errorf("lost lease %s: %v", e.key, err)
			}

		case <-lost:
			return fmt.Errorf("the lease has been lost %s", e.key)
		}
	}
}