First draft of logging functionality.

[Michal Sojka]

On Tue, 12 Oct 2010, David Bremner wrote:
> On Tue, 12 Oct 2010 11:06:17 +0200, Michal Sojka <sojkam1 at fel.cvut.cz> wrote:
> 
> > I'm not sure whether implementing logging facility outside of notmuch
> > library is a good thing. If somebody will use a third-party tool (such
> > as python bindings) to manipulate his tags, they won't appear in the
> > log.
> 
> Yeah, thanks for that. I had been worrying about the same thing, but
> your message helped clarify things for me.
> 
> I guess log files should be opened in notmuch_database_open, and the
> actual logging in this case could happen from notmuch_message_add_tag.
> 
> From an atomicity point of view it might make more sense to store up a
> list of log lines, and dump them all from _notmuch_message_sync.
> One could attach a log buffer to a message, and flush that atomically
> when syncing the message back to the database.

Yes, the above sounds good to me.

> In this context, it is a little more tedious to have more than one log
> file.

Why multiple log files? You may have the buffers for message logs in
memory, right?

Another thing to keep in mind is how it will behave with 'notmuch
restore'. If do dump followed by resore you will have a very long log
with no useful information in it. Some optimization may be employed here.

Bye
-Michal