// maybeBeginTxn begins a new transaction if a txn has been specified
// in the request but has a nil ID. The new transaction is initialized
// using the name and isolation in the otherwise uninitialized txn.
// The Priority, if non-zero is used as a minimum.
func (tc *TxnCoordSender) maybeBeginTxn(header *proto.RequestHeader) {
if header.Txn != nil {
if len(header.Txn.ID) == 0 {
newTxn := proto.NewTransaction(header.Txn.Name, keys.KeyAddress(header.Key), header.GetUserPriority(),
header.Txn.Isolation, tc.clock.Now(), tc.clock.MaxOffset().Nanoseconds())
// Use existing priority as a minimum. This is used on transaction
// aborts to ratchet priority when creating successor transaction.
if newTxn.Priority < header.Txn.Priority {
newTxn.Priority = header.Txn.Priority
}
header.Txn = newTxn
}
}
}
// updateForBatch updates the first argument (the header of a request contained
// in a batch) from the second one (the batch header), returning an error when
// inconsistencies are found.
// It is checked that the individual call does not have a User, UserPriority
// or Txn set that differs from the batch's.
func updateForBatch(aHeader *proto.RequestHeader, bHeader proto.RequestHeader) error {
// Disallow transaction, user and priority on individual calls, unless
// equal.
if aHeader.User != "" && aHeader.User != bHeader.User {
return util.Error("conflicting user on call in batch")
}
if aPrio := aHeader.GetUserPriority(); aPrio != proto.Default_RequestHeader_UserPriority && aPrio != bHeader.GetUserPriority() {
return util.Error("conflicting user priority on call in batch")
}
if aHeader.Txn != nil && !aHeader.Txn.Equal(bHeader.Txn) {
return util.Error("conflicting transaction in transactional batch")
}
aHeader.User = bHeader.User
aHeader.UserPriority = bHeader.UserPriority
aHeader.Txn = bHeader.Txn
return nil
}