[PATCHES] Logging to multiple debug backends

[Christof Schmitt]

On Tue, Mar 17, 2015 at 09:06:52PM +1100, Martin Schwenke wrote:
> On Tue, 17 Mar 2015 10:31:41 +0100, Volker Lendecke
> <Volker.Lendecke at SerNet.DE> wrote:
> 
> > On Mon, Mar 16, 2015 at 01:54:26PM -0700, Christof Schmitt wrote:
> > > I started implementing a separate array, see the attached patch. So far
> > > it compiles, but it is untested. Does that fit your idea?
> > 
> > Ooops. Sorry, I did not mean this as a serious suggestion. I
> > really doubt we will ever see this in profiles, because most
> > of the filtering load is already done in the DEBUG macro. We
> > only end up here if we have something to print, and any
> > snprintf load or even write(2) calls will completely
> > overwhelm this. If at one point we have dozens of backends
> > compiled in, we will need to do something, but I think a
> > typical configuration will have at most 4 compiled in at
> > all.
> > 
> > I would rather have liked Martin to squash my arguments :-)
> 
> Yeah, yeah...  :-)
> 
> After I sent that email I did actually think about the locality of
> reference issue with a linked list.  However, I wanted to see what
> others thought.  When you replied I did think it was potential
> over-engineering and whether we'd see any benefit.  :-)
> 
> Sorry, Christof... I also didn't mean to waste your time.  :-(

No worries, we can agree that this would be over-engineering :-)

> One thing the linked list gives you is some help in simplifying the
> struct and API as I suggested.  There are various hacks I can think of
> but none of them are elegant.
> 
> I still think the changes in the other 1/2 of the thread (ability to
> pass options, changing API) are worthwhile.  I'll try to reply to that
> soon...  and come up with something pretty for the API/struct thing.

I assume that you are trying to get the code ready for moving some of
the ctdb logging backends. Since this is only an API internal to
debug.c, we can change that anytime. I would propose that we agree on a
format used in the 'logging' parameter for passing additional options,
and make sure that we don't need to change that format going forward.
Then we could work towards getting the current patch set in master.

Moving the ctdb logging backends can be done later. As the required
changes are only internal to debug.c, we can do that at any time.

Does this sound like a plan?

Christof