func MaybeCreateRoot(topology *server.Topology, conns map[common.RMId]paxos.Connection, cm *ConnectionManager, lc *client.LocalConnection) error {
if topology.RootVarUUId != nil {
return nil
}
requiredKnownRMs := int(topology.TwoFInc)
if len(topology.AllRMs) < requiredKnownRMs {
return nil
}
activeRMs := make([]common.RMId, 0, int(topology.FInc))
passiveRMs := make([]common.RMId, 0, int(topology.F))
for _, rmId := range topology.AllRMs[:requiredKnownRMs] {
if _, found := conns[rmId]; found && len(activeRMs) < cap(activeRMs) {
activeRMs = append(activeRMs, rmId)
} else {
passiveRMs = append(passiveRMs, rmId)
}
}
if len(activeRMs) < cap(activeRMs) {
return nil
}
server.Log("Creating Root. Actives:", activeRMs, "; Passives:", passiveRMs)
for {
seg := capn.NewBuffer(nil)
txn := msgs.NewTxn(seg)
txn.SetSubmitter(uint32(cm.RMId))
txn.SetSubmitterBootCount(cm.BootCount)
actions := msgs.NewActionList(seg, 1)
txn.SetActions(actions)
action := actions.At(0)
vUUId := lc.NextVarUUId()
action.SetVarId(vUUId[:])
action.SetCreate()
create := action.Create()
positions := seg.NewUInt8List(int(topology.MaxRMCount))
create.SetPositions(positions)
for idx, l := 0, positions.Len(); idx < l; idx++ {
positions.Set(idx, uint8(idx))
}
create.SetValue([]byte{})
create.SetReferences(msgs.NewVarIdPosList(seg, 0))
allocs := msgs.NewAllocationList(seg, requiredKnownRMs)
txn.SetAllocations(allocs)
idx := 0
for listIdx, rmIds := range [][]common.RMId{activeRMs, passiveRMs} {
for _, rmId := range rmIds {
alloc := allocs.At(idx)
idx++
alloc.SetRmId(uint32(rmId))
if listIdx == 0 {
alloc.SetActive(conns[rmId].BootCount())
} else {
alloc.SetActive(0)
}
indices := seg.NewUInt16List(1)
alloc.SetActionIndices(indices)
indices.Set(0, 0)
}
}
txn.SetFInc(topology.FInc)
txn.SetTopologyVersion(topology.Version)
result, err := lc.RunTransaction(&txn, true, activeRMs...)
if err != nil {
return err
}
if result == nil {
return nil
}
if result.Which() == msgs.OUTCOME_COMMIT {
server.Log("Root created in", vUUId)
topology.RootVarUUId = vUUId
topology.RootPositions = (*common.Positions)(&positions)
return nil
}
abort := result.Abort()
if abort.Which() == msgs.OUTCOMEABORT_RESUBMIT {
continue
}
return fmt.Errorf("Internal error: creation of root gave rerun outcome")
}
}
