Beispiel #1
0
// forward is used to forward to a remote region or to forward to the local leader
// Returns a bool of if forwarding was performed, as well as any error
func (s *Server) forward(method string, info structs.RPCInfo, args interface{}, reply interface{}) (bool, error) {
	var firstCheck time.Time

	region := info.RequestRegion()
	if region == "" {
		return true, fmt.Errorf("missing target RPC")
	}

	// Handle region forwarding
	if region != s.config.Region {
		err := s.forwardRegion(region, method, args, reply)
		return true, err
	}

	// Check if we can allow a stale read
	if info.IsRead() && info.AllowStaleRead() {
		return false, nil
	}

CHECK_LEADER:
	// Find the leader
	isLeader, remoteServer := s.getLeader()

	// Handle the case we are the leader
	if isLeader {
		return false, nil
	}

	// Handle the case of a known leader
	if remoteServer != nil {
		err := s.forwardLeader(remoteServer, method, args, reply)
		return true, err
	}

	// Gate the request until there is a leader
	if firstCheck.IsZero() {
		firstCheck = time.Now()
	}
	if time.Now().Sub(firstCheck) < s.config.RPCHoldTimeout {
		jitter := lib.RandomStagger(s.config.RPCHoldTimeout / jitterFraction)
		select {
		case <-time.After(jitter):
			goto CHECK_LEADER
		case <-s.shutdownCh:
		}
	}

	// No leader found and hold time exceeded
	return true, structs.ErrNoLeader
}
Beispiel #2
0
// forward is used to forward to a remote region or to forward to the local leader
// Returns a bool of if forwarding was performed, as well as any error
func (s *Server) forward(method string, info structs.RPCInfo, args interface{}, reply interface{}) (bool, error) {
	region := info.RequestRegion()
	if region == "" {
		return true, fmt.Errorf("missing target RPC")
	}

	// Handle region forwarding
	if region != s.config.Region {
		err := s.forwardRegion(region, method, args, reply)
		return true, err
	}

	// Check if we can allow a stale read
	if info.IsRead() && info.AllowStaleRead() {
		return false, nil
	}

	// Handle leader forwarding
	if !s.IsLeader() {
		err := s.forwardLeader(method, args, reply)
		return true, err
	}
	return false, nil
}