Subject: Re: [PATCH v3 7/8] fetch-pack: put shallow info in output parameter

From: Brandon Williams <[email-masked]>
Date: Mon, 25 Jun 2018 11:18:20 -0700

On 06/25, Jonathan Tan wrote:
> >  static void update_shallow(struct fetch_pack_args *args,
> > -			   struct ref **sought, int nr_sought,
> > +			   struct ref *refs,
> 
> update_shallow() now takes in a linked list of refs instead of an array.
> I see that the translation of this function is straightforward -
> occasionally, we need to iterate through the linked list and count up
> from 0 at the same time, but that is not a problem.
> 
> >  			   struct shallow_info *si)
> >  {
> >  	struct oid_array ref = OID_ARRAY_INIT;
> >  	int *status;
> > -	int i;
> > +	int i = 0;
> 
> Remove the " = 0" - I've verified that it does not need to be there, and
> it might inhibit useful "unintialized variable" warnings if others were
> to change the code later.
> 
> Optional: I would also remove this declaration and declare "int i;" in
> each of the blocks that need it.
> 
> >  static int fetch_refs_via_pack(struct transport *transport,
> > -			       int nr_heads, struct ref **to_fetch)
> > +			       int nr_heads, struct ref **to_fetch,
> > +			       struct ref **fetched_refs)
> >  {
> >  	int ret = 0;
> >  	struct git_transport_data *data = transport->data;
> > @@ -354,8 +356,12 @@ static int fetch_refs_via_pack(struct transport *transport,
> >  	if (report_unmatched_refs(to_fetch, nr_heads))
> >  		ret = -1;
> >  
> > +	if (fetched_refs)
> > +		*fetched_refs = refs;
> > +	else
> > +		free_refs(refs);
> > +
> >  	free_refs(refs_tmp);
> > -	free_refs(refs);
> >  	free(dest);
> >  	return ret;
> >  }
> 
> Instead of just freeing the linked list, we return it if requested by
> the client. This makes sense.
> 
> > -int transport_fetch_refs(struct transport *transport, struct ref *refs)
> > +int transport_fetch_refs(struct transport *transport, struct ref *refs,
> > +			 struct ref **fetched_refs)
> >  {
> >  	int rc;
> >  	int nr_heads = 0, nr_alloc = 0, nr_refs = 0;
> >  	struct ref **heads = NULL;
> > +	struct ref *nop_head = NULL, **nop_tail = &nop_head;
> >  	struct ref *rm;
> >  
> >  	for (rm = refs; rm; rm = rm->next) {
> >  		nr_refs++;
> >  		if (rm->peer_ref &&
> >  		    !is_null_oid(&rm->old_oid) &&
> > -		    !oidcmp(&rm->peer_ref->old_oid, &rm->old_oid))
> > +		    !oidcmp(&rm->peer_ref->old_oid, &rm->old_oid)) {
> > +			/*
> > +			 * These need to be reported as fetched, but we don't
> > +			 * actually need to fetch them.
> > +			 */
> > +			if (fetched_refs) {
> > +				struct ref *nop_ref = copy_ref(rm);
> > +				*nop_tail = nop_ref;
> > +				nop_tail = &nop_ref->next;
> > +			}
> >  			continue;
> > +		}
> >  		ALLOC_GROW(heads, nr_heads + 1, nr_alloc);
> >  		heads[nr_heads++] = rm;
> >  	}
> > @@ -1245,7 +1263,11 @@ int transport_fetch_refs(struct transport *transport, struct ref *refs)
> >  			heads[nr_heads++] = rm;
> >  	}
> >  
> > -	rc = transport->vtable->fetch(transport, nr_heads, heads);
> > +	rc = transport->vtable->fetch(transport, nr_heads, heads, fetched_refs);
> > +	if (fetched_refs && nop_head) {
> > +		*nop_tail = *fetched_refs;
> > +		*fetched_refs = nop_head;
> > +	}
> >  
> >  	free(heads);
> >  	return rc;
> 
> And sometimes, even if we are merely simulating the fetching of refs, we
> still need to report those refs in fetched_refs. This is correct.
> 
> I also see that t5703 now passes.
> 
> Besides enabling the writing of subsequent patches, I see that this also
> makes the API clearer in that the input refs to transport_fetch_refs()
> are not overloaded to output shallow information. Other than the " = 0"
> change above, this patch looks good to me.

Perfect, I'll just drop the " = 0" part (making the diff slightly
smaller)

-- 
Brandon Williams