// 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
}
// 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
}