{{Quickfixn}} Report of an issue / Proposal for change

[Grant Birchmeier]

This looks like a reasonable and good suggestion.

I created issue 987 for it:
https://github.com/connamara/quickfixn/issues/987

I hope to take a deeper look within the next month or 2.

On Thu, Oct 30, 2025 at 5:02 AM Andreas Meisner via Quickfixn <
quickfixn at lists.quickfixn.com> wrote:

> Hi @all,
>
> this is my first email on this list and I am not yet familiar with the
> rules here.
>
> I have found the following issue, because I have implemented a
> IMessageStore for MSSQL server (using EF) having indices on the database
> tables:
>
> In class Session we have the method Persist(Message, string):
>
>          protected void Persist(Message message, string messageString)
>          {
>              if (PersistMessages)
>              {
>                  SeqNumType msgSeqNum =
> message.Header.GetULong(Fields.Tags.MsgSeqNum);
>                  _state.Set(msgSeqNum, messageString);
>              }
>              _state.IncrNextSenderMsgSeqNum();
>          }
>
> The call of Set() and IncrNextSenderMsgSeqNum() should be in one
> transaction, but currently I have a straight forward implementation with
> no dependencies between these methods. In my case a call to Set() was
> successful, but the call to IncrNextSenderMsgSeqNum() failed, leaving
> the database in an inconsitant state. I think the same could happen when
> using FileStore, but here we do not have an index that could cause an
> exception.
>
> I can catch this in my DbMessageStore implementation, but it would be
> nicer to have only one method in this case.
>
> So my proposal for a change is:
>
>
> 1. Add a new method in interface IMessageStore with a default
> implementation:
>
> public interface IMessageStore : IDisposable
> {
>
>      // ... existing members
>
>      public bool SetAndIncrNextSenderMsgSeqNum(SeqNumType msgSeqNum,
> string msg)
>      {
>          bool result = Set(msgSeqNum, msg);
>          IncrNextSenderMsgSeqNum();
>          return result;
>      }
> }
>
> 2. Add the method with the same signature to class SessionState:
>
>          public bool SetAndIncrNextSenderMsgSeqNum(SeqNumType msgSeqNum,
> string msg)
>          {
>              lock (_sync) { return
> MessageStore.SetAndIncrNextSenderMsgSeqNum(msgSeqNum, msg); }
>          }
>
> 3. Call the new method in class Session:
>
>          protected void Persist(Message message, string messageString)
>          {
>              if (PersistMessages)
>              {
>                  SeqNumType msgSeqNum =
> message.Header.GetULong(Fields.Tags.MsgSeqNum);
>                  _state.SetAndIncrNextSenderMsgSeqNum(msgSeqNum,
> messageString);
>              }
>              else
>              {
>                  _state.IncrNextSenderMsgSeqNum();
>              }
>          }
>
> This change should be 99.9% backwards compatible and should not affect
> any existing implementation. The only difference (the 0.1%) is that the
> call to Set() and IncrNextSenderMsgSeqNum() is in one lock(_sync) in
> class SessionState, but this should be also an improvement.
>
> Please let me know, if I can add a new pull request with these changes.
>
>
> Thanks,
> Andreas
>
>
> --
> Andreas Meisner
> Software-Development
>
> C/Poeto Alonso Quesada 30
> 35310 Santa Brígida
> Las Palmas Gran Canaria
> Spain
>
> Tel. +49 176 42026763
> Email: software at meisner.de
> Web: http://software.meisner.de
>
> N.I.E. Y-9624964-F
>
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> Quickfixn at lists.quickfixn.com
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>


-- 
<https://www.connamara.com>

Grant Birchmeier

Director of Engineering, Connamara

gbirchmeier at connamara.com

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