func (fo *frameOpen) createRollClientTxn() (*cmsgs.ClientTxn, map[common.VarUUId]*common.Positions) {
var origWrite *msgs.Action
vUUIdBytes := fo.v.UUId[:]
for idx, l := 0, fo.frameTxnActions.Len(); idx < l; idx++ {
action := fo.frameTxnActions.At(idx)
if bytes.Equal(action.VarId(), vUUIdBytes) {
origWrite = &action
break
}
}
seg := capn.NewBuffer(nil)
ctxn := cmsgs.NewClientTxn(seg)
ctxn.SetRetry(false)
actions := cmsgs.NewClientActionList(seg, 1)
ctxn.SetActions(actions)
action := actions.At(0)
action.SetVarId(fo.v.UUId[:])
action.SetRoll()
roll := action.Roll()
roll.SetVersion(fo.frameTxnId[:])
var refs msgs.VarIdPos_List
switch origWrite.Which() {
case msgs.ACTION_WRITE:
ow := origWrite.Write()
roll.SetValue(ow.Value())
refs = ow.References()
case msgs.ACTION_READWRITE:
owr := origWrite.Readwrite()
roll.SetValue(owr.Value())
refs = owr.References()
case msgs.ACTION_CREATE:
oc := origWrite.Create()
roll.SetValue(oc.Value())
refs = oc.References()
case msgs.ACTION_ROLL:
owr := origWrite.Roll()
roll.SetValue(owr.Value())
refs = owr.References()
default:
panic(fmt.Sprintf("%v unexpected action type when building roll: %v", fo.frame, origWrite.Which()))
}
posMap := make(map[common.VarUUId]*common.Positions)
posMap[*fo.v.UUId] = fo.v.positions
refVarList := seg.NewDataList(refs.Len())
roll.SetReferences(refVarList)
for idx, l := 0, refs.Len(); idx < l; idx++ {
ref := refs.At(idx)
vUUId := common.MakeVarUUId(ref.Id())
pos := common.Positions(ref.Positions())
posMap[*vUUId] = &pos
refVarList.Set(idx, vUUId[:])
}
return &ctxn, posMap
}
func (bra *badReadAction) combine(action *msgs.Action, rmBal *rmBallot, txnId *common.TxnId, clockElem uint64) {
newActionType := action.Which()
braActionType := bra.action.Which()
switch {
case braActionType != msgs.ACTION_READ && newActionType != msgs.ACTION_READ:
// They're both writes in some way. Just order the txns
if clockElem > bra.clockElem || (clockElem == bra.clockElem && bra.txnId.Compare(txnId) == common.LT) {
bra.set(action, rmBal, txnId, clockElem)
}
case braActionType == msgs.ACTION_READ && newActionType == msgs.ACTION_READ:
braRead := bra.action.Read()
newRead := action.Read()
clockElem--
// If they read the same version, we really don't care.
if !bytes.Equal(braRead.Version(), newRead.Version()) {
// They read different versions, but which version was the latter?
if clockElem > bra.clockElem {
bra.set(action, rmBal, common.MakeTxnId(newRead.Version()), clockElem)
}
}
case braActionType == msgs.ACTION_READ:
if bytes.Equal(bra.txnId[:], txnId[:]) {
// The write will obviously be in the past of the
// existing read, but it's better to have the write
// as we can update the client with the actual
// value.
bra.set(action, rmBal, txnId, clockElem)
} else if clockElem > bra.clockElem {
// The write is after than the read
bra.set(action, rmBal, txnId, clockElem)
}
default: // Existing is not a read, but new is a read.
newRead := action.Read()
clockElem--
// If the read is a read of the existing write, better to keep the write
if !bytes.Equal(bra.txnId[:], newRead.Version()) {
if clockElem > bra.clockElem {
// The read must be of some value which was written after our existing write.
bra.set(action, rmBal, common.MakeTxnId(newRead.Version()), clockElem)
}
}
}
}
