Re: [PATCH 3/7] release_delta_base_cache: reuse existing detach function

From: Jeff King <peff@peff.net>
Date: Aug 24, 2016, 17:41 UTC
Message-ID: <20160824174122.372c7pi4ub5bxcat@sigill.intra.peff.net>
In-Reply-To: <xmqqwpj7tauc.fsf@gitster.mtv.corp.google.com>

On Tue, Aug 23, 2016 at 02:49:15PM -0700, Junio C Hamano wrote:

Show 17 quoted lines

> > diff --git a/sha1_file.c b/sha1_file.c
> > index 1d0810c..8264b39 100644
> > --- a/sha1_file.c
> > +++ b/sha1_file.c
> > @@ -2152,10 +2152,7 @@ static inline void release_delta_base_cache(struct delta_base_cache_entry *ent)
> >  {
> >  	if (ent->data) {
> >  		free(ent->data);
> > -		ent->data = NULL;
> > -		ent->lru.next->prev = ent->lru.prev;
> > -		ent->lru.prev->next = ent->lru.next;
> > -		delta_base_cached -= ent->size;
> > +		detach_delta_base_cache_entry(ent);
> 
> If we were designing this from scratch, we might have made detach_*
> to return the pointer to minimize direct access to ent->data, but I
> do not think it is worth it.  Looks very sensible.

I actually looked into that during the conversion in patch 2/7. I didn't want to just return ent->data, because there are actually several bits of information to "rescue" from the entry. So it looks more like:

  char *data = detach_delta_base_cache_entry(ent, NULL, NULL);
  free(data);

here, and

  data = detach_delta_base_cache_entry(ent, &type, &size);

in unpack_entry().

That is not too bad, I guess. I can switch it if you prefer that way. Since there are only these two callers with two different sets of needs (and the function is static), I just let them continue inspecting the elements directly.

-Peff