// Phase1RPC handles ClassicPaxos.Phase1 rpc.
func (this *Paxos) Phase1RPC(header *msgpb.Header,
request *thispb.Phase1Request) (status error) {
if !this.IsAcceptor() {
this.Errorf("this paxos instance is not an acceptor; rejecting %s", header)
return errs.ErrInvalid
}
lock, errLock := this.ctlr.TimedLock(msg.RequestTimeout(header),
"acceptor")
if errLock != nil {
return errLock
}
defer lock.Unlock()
clientID := header.GetMessengerId()
respond := func() error {
response := thispb.Phase1Response{}
response.PromisedBallot = proto.Int64(this.promisedBallot)
if this.votedBallot >= 0 {
response.VotedBallot = proto.Int64(this.votedBallot)
response.VotedValue = this.votedValue
}
message := thispb.PaxosMessage{}
message.Phase1Response = &response
errSend := msg.SendResponseProto(this.msn, header, &message)
if errSend != nil {
this.Errorf("could not send phase1 response to %s: %v", clientID,
errSend)
return errSend
}
return nil
}
ballot := request.GetBallotNumber()
if ballot < this.promisedBallot {
this.Warningf("phase1 request from %s is ignored due to stale ballot %d",
clientID, ballot)
return respond()
}
if ballot == this.promisedBallot {
this.Warningf("duplicate phase1 request from client %s with an already "+
"promised ballot number %d", clientID, ballot)
return respond()
}
// Save the promise into the wal.
change := thispb.AcceptorChange{}
change.PromisedBallot = proto.Int64(ballot)
if err := this.doUpdateAcceptor(&change); err != nil {
this.Errorf("could not update acceptor state: %v", err)
return err
}
this.Infof("this acceptor has now promised higher ballot %d from %s", ballot,
clientID)
return respond()
}
