Exemplo n.º 1
0
// 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 tools.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
}
Exemplo n.º 2
0
// setCommandFunc executes the "set" command.
func setCommandFunc(cmd *cobra.Command, args []string, client *etcd.Client) (*etcd.Response, error) {
	if len(args) == 0 {
		return nil, errors.New("Key required")
	}
	key := args[0]
	value, err := argOrStdin(args, os.Stdin, 1)
	if err != nil {
		return nil, errors.New("Value required")
	}

	ttl := ttlFlag
	prevValue := swapWithValueFlag
	prevIndex := swapWithIndexFlag

	if prevValue == "" && prevIndex == 0 {
		return client.Set(key, value, uint64(ttl))
	} else {
		return client.CompareAndSwap(key, value, uint64(ttl), prevValue, uint64(prevIndex))
	}
}
Exemplo n.º 3
0
func CASEpoch(client *etcd.Client, appname string, prevEpoch, epoch uint64) error {
	prevEpochStr := strconv.FormatUint(prevEpoch, 10)
	epochStr := strconv.FormatUint(epoch, 10)
	_, err := client.CompareAndSwap(EpochPath(appname), epochStr, 0, prevEpochStr, 0)
	return err
}