// 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 UserPriority
// or Txn set that differs from the batch's.
// TODO(tschottdorf): will go with #2143.
func updateForBatch(args roachpb.Request, bHeader roachpb.BatchRequest_Header) error {
// Disallow transaction, user and priority on individual calls, unless
// equal.
aHeader := args.Header()
if aPrio := aHeader.GetUserPriority(); aPrio != roachpb.Default_RequestHeader_UserPriority && aPrio != bHeader.GetUserPriority() {
return util.Errorf("conflicting user priority on call in batch")
}
aHeader.UserPriority = bHeader.UserPriority
aHeader.Txn = bHeader.Txn // reqs always take Txn from batch
return nil
}
// SendWrappedAt is a convenience function which wraps the request in a batch
// and sends it via the provided Sender at the given timestamp. It returns the
// unwrapped response or an error. It's valid to pass a `nil` context;
// context.Background() is used in that case.
func SendWrappedAt(sender Sender, ctx context.Context, ts roachpb.Timestamp, args roachpb.Request) (roachpb.Response, error) {
if ctx == nil {
ctx = context.Background()
}
ba, unwrap := func(args roachpb.Request) (*roachpb.BatchRequest, func(*roachpb.BatchResponse) roachpb.Response) {
ba := &roachpb.BatchRequest{}
ba.Timestamp = ts
{
h := args.Header()
ba.Key, ba.EndKey = h.Key, h.EndKey
ba.CmdID = h.CmdID
ba.Replica = h.Replica
ba.RangeID = h.RangeID
ba.UserPriority = h.UserPriority
ba.Txn = h.Txn
ba.ReadConsistency = h.ReadConsistency
}
ba.Add(args)
return ba, func(br *roachpb.BatchResponse) roachpb.Response {
unwrappedReply := br.Responses[0].GetInner()
// The ReplyTxn is propagated from one response to the next request,
// and we adopt the mechanism that whenever the Txn changes, it needs
// to be set in the reply, for example to ratchet up the transaction
// timestamp on writes when necessary.
// This is internally necessary to sequentially execute the batch,
// so it makes some sense to take the burden of updating the Txn
// from TxnCoordSender - it will only need to act on retries/aborts
// in the future.
unwrappedReply.Header().Txn = br.Txn
return unwrappedReply
}
}(args)
br, pErr := sender.Send(ctx, *ba)
if err := pErr.GoError(); err != nil {
return nil, err
}
return unwrap(br), nil
}