Re: Hammer: Transactional file updates

[Michael Neumann <mneumann@xxxxxxxx>]

Daniel Taylor wrote:
> --- On Fri, 1/8/08, Michael Neumann <mneumann@ntecs.de> wrote:
>
> >    fd = open(file);  // behaves like START TRANSACTION
> >    read(fd, ...);
> >    write(fd, ...);
> >    close(fd);        // behaves like COMMIT
>
> If you want a commit on close, fsync() the file just before you close() it.

That's not what I want. fsync only guarantees that the data is stored
permanently. That's not my problem. I want to ensure that some
write-operations are performed either-all-or-nothing.

> > That would be fine except that it would give me a new inode
> > number, and
> > the inode number is right now the only way to associate
> > further data
> > with a file.
>
> Why do you care if you get a new inode vs multiple versions of the same inode?

Hammer doesn't reuse inode numbers. So inode numbers could be used as
unique id's to refer to that file (like a ROWID or OID in a database).

Regards,

  Michael