Re: [PATCH v5 04/16] promisor-remote: implement promisor_remote_get_direct()

> On 5/30/2019 4:46 PM, Johannes Schindelin wrote:
> >
> > On Thu, 30 May 2019, Derrick Stolee wrote:
> >
> >> On 4/9/2019 12:11 PM, Christian Couder wrote:
> >>> From: Christian Couder <christian.couder@gmail.com>
> >>>
> >>> +{
> >>> +	int i, missing_nr = 0;
> >>> +	int *missing = xcalloc(oid_nr, sizeof(*missing));
> >>> +	struct object_id *old_oids = *oids;
> >>> +	struct object_id *new_oids;
> >>> +	int old_fetch_if_missing = fetch_if_missing;
> >>> +
> >>> +	fetch_if_missing = 0;
> >>
> >> This global 'fetch_if_missing' swap seems very fragile. I'm guessing you
> >> are using it to prevent a loop when calling oid_object_info_extended()
> >> below. Can you instead pass a flag to the method that disables the
> >> fetch_if_missing behavior?
> >
> > FWIW I mentioned the very same concern here:
> > https://public-inbox.org/git/nycvar.QRO.7.76.6.1903272300020.41@tvgsbejvaqbjf.bet/
> >
> > The situation is *pretty* bad by now. I see `fetch_if_missing` mentioned
> > 25 times in `master`, and all but one are in .c files or in cache.h.
> >
> > The flag is actually used only in `oid_object_info_extended()`, and that
> > function accepts an `unsigned flags`, so one might think that it could be
> > extended to accept also a `OBJECT_INFO_LOOKUP_FETCH_IF_MISSING`. But then,
> > there are many callers of that function, some of them also pretty low in
> > the food chain. For example, `oid_object_info()` (does not accept `flags`)
> > or `read_object()` (does not accept flags either).
> >
> > So it looks as if the idea to pass this flag down the call chain entailed
> > a pretty serious avalanche effect.
>
> It could be approached in small bits.
>
> First, add an OBJECT_INFO_NEVER_FETCH_IF_MISSING flag that overrides
> fetch_if_missing, and then use the flag in small places like this one.
> Then, build up to the other methods as appropriate.

> > An alternative that strikes me as inelegant, still, but nevertheless
> > better would be to move `fetch_if_missing` into `struct repository`.
>
> This is literally the _least_ we should do to reduce our dependence on
> globals. Maybe this happens first, then the flag idea could be done bits
> at a time.