func (this *Paxos) doSaveConfiguration(config *thispb.Configuration) {
config.MajoritySize = proto.Int32(this.majoritySize)
config.ProposerList = append([]string{}, this.proposerList...)
config.AcceptorList = append([]string{}, this.acceptorList...)
config.LearnerList = append([]string{}, this.learnerList...)
if this.IsProposer() {
config.IsProposer = proto.Bool(true)
config.ProposerIndex = proto.Int32(int32(this.proposerIndex))
}
if this.IsAcceptor() {
config.IsAcceptor = proto.Bool(true)
}
if this.IsLearner() {
config.IsLearner = proto.Bool(true)
}
}
// Configure initializes the paxos agent configuration. Since classic paxos
// doesn't support reconfiguration, this operation can be performed only
// once. Also, local object can be used as a client if it doesn't take any
// role.
//
// proposerList: List of proposer messenger names.
//
// acceptorList: List of acceptor messenger names.
//
// learnerList: List of learner messenger names.
//
// Returns nil on success.
func (this *Paxos) Configure(proposerList, acceptorList,
learnerList []string) error {
lock, errLock := this.ctlr.LockAll()
if errLock != nil {
return errLock
}
defer lock.Unlock()
if this.majoritySize > 0 {
this.Errorf("paxos instance is already configured")
return errs.ErrExist
}
// TODO: Check for duplicates.
learners := make([]string, len(learnerList))
copy(learners, learnerList)
sort.Sort(sort.StringSlice(learners))
acceptors := make([]string, len(acceptorList))
copy(acceptors, acceptorList)
sort.Sort(sort.StringSlice(acceptors))
majoritySize := len(acceptors)/2 + 1
proposers := make([]string, len(proposerList))
copy(proposers, proposerList)
sort.Sort(sort.StringSlice(proposers))
self := this.msn.UID()
isLearner := false
for _, learner := range learners {
if learner == self {
isLearner = true
break
}
}
isAcceptor := false
for _, acceptor := range acceptors {
if acceptor == self {
isAcceptor = true
break
}
}
isProposer := false
proposerIndex := -1
for ii, proposer := range proposers {
if proposer == self {
isProposer = true
proposerIndex = ii
break
}
}
// Save configuration in the wal.
config := thispb.Configuration{}
config.LearnerList = learners
config.ProposerList = proposers
config.AcceptorList = acceptors
config.MajoritySize = proto.Int32(int32(majoritySize))
if isLearner {
config.IsLearner = proto.Bool(true)
}
if isAcceptor {
config.IsAcceptor = proto.Bool(true)
}
if isProposer {
config.IsProposer = proto.Bool(true)
config.ProposerIndex = proto.Int32(int32(proposerIndex))
}
return this.doUpdateConfig(&config)
}
func (this *Paxos) doRestoreConfig(config *thispb.Configuration) {
this.learnerList = config.GetLearnerList()
this.proposerList = config.GetProposerList()
this.acceptorList = config.GetAcceptorList()
if config.IsLearner != nil && config.GetIsLearner() {
atomic.StoreInt32(&this.isLearner, 1)
}
if config.IsAcceptor != nil && config.GetIsAcceptor() {
atomic.StoreInt32(&this.isAcceptor, 1)
}
if config.IsProposer != nil && config.GetIsProposer() {
atomic.StoreInt32(&this.isProposer, 1)
this.proposerIndex = int(config.GetProposerIndex())
}
if config.MajoritySize != nil {
atomic.StoreInt32(&this.majoritySize, config.GetMajoritySize())
}
}