// Phase2RPC handles ClassicPaxos.Phase2 rpc.
func (this *Paxos) Phase2RPC(header *msgpb.Header,
request *thispb.Phase2Request) (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.Phase2Response{}
response.PromisedBallot = proto.Int64(this.promisedBallot)
if this.votedBallot >= 0 {
response.VotedBallot = proto.Int64(this.votedBallot)
response.VotedValue = this.votedValue
}
message := thispb.PaxosMessage{}
message.Phase2Response = &response
errSend := msg.SendResponseProto(this.msn, header, &message)
if errSend != nil {
this.Errorf("could not send phase2 response to %s: %v", clientID,
errSend)
return errSend
}
return nil
}
ballot := request.GetBallotNumber()
if ballot < this.promisedBallot {
this.Warningf("phase2 request from %s is ignored due to stale ballot %d",
clientID, ballot)
return respond()
}
if ballot > this.promisedBallot {
this.Errorf("phase2 request from client %s without acquiring a prior "+
"promise", clientID)
return respond()
}
value := request.GetProposedValue()
// Save the phase2 vote into the wal.
change := thispb.AcceptorChange{}
change.VotedBallot = proto.Int64(ballot)
change.VotedValue = value
if err := this.doUpdateAcceptor(&change); err != nil {
this.Errorf("could not update acceptor state: %v", err)
return err
}
this.Infof("this acceptor has voted for %d in ballot %s", ballot, value)
if err := respond(); err != nil {
return err
}
// Schedule a notification to all learners.
_ = this.alarm.ScheduleAt(this.uid, time.Now(), this.NotifyAllLearners)
return nil
}
