Re: [RFC PATCH] transport: list refs before fetch if necessary
- From
Junio C Hamano <gitster@pobox.com>
- Date
- Sep 25, 2018, 23:09 UTC
- Message-ID
- <xmqq8t3pnphe.fsf@gitster-ct.c.googlers.com>
- In-Reply-To
- <20180925225355.74237-1-jonathantanmy@google.com>
Jonathan Tan <jonathantanmy@google.com> writes:
Show 57 quoted lines
> diff --git a/transport-helper.c b/transport-helper.c
> index 143ca008c8..7213fa0d32 100644
> --- a/transport-helper.c
> +++ b/transport-helper.c
> @@ -1105,6 +1105,7 @@ static struct ref *get_refs_list(struct transport *transport, int for_push,
> }
>
> static struct transport_vtable vtable = {
> + 0,
> set_helper_option,
> get_refs_list,
> fetch,
> diff --git a/transport-internal.h b/transport-internal.h
> index 1cde6258a7..004bee5e36 100644
> --- a/transport-internal.h
> +++ b/transport-internal.h
> @@ -6,6 +6,12 @@ struct transport;
> struct argv_array;
>
> struct transport_vtable {
> + /**
> + * This transport supports the fetch() function being called
> + * without get_refs_list() first being called.
> + */
> + unsigned fetch_without_list : 1;
> +
> /**
> * Returns 0 if successful, positive if the option is not
> * recognized or is inapplicable, and negative if the option
> diff --git a/transport.c b/transport.c
> index 1c76d64aba..ee8a78ff37 100644
> --- a/transport.c
> +++ b/transport.c
> @@ -703,6 +703,7 @@ static int disconnect_git(struct transport *transport)
> }
>
> static struct transport_vtable taken_over_vtable = {
> + 1,
> NULL,
> get_refs_via_connect,
> fetch_refs_via_pack,
> @@ -852,6 +853,7 @@ void transport_check_allowed(const char *type)
> }
>
> static struct transport_vtable bundle_vtable = {
> + 0,
> NULL,
> get_refs_from_bundle,
> fetch_refs_from_bundle,
> @@ -861,6 +863,7 @@ static struct transport_vtable bundle_vtable = {
> };
>
> static struct transport_vtable builtin_smart_vtable = {
> + 1,
> NULL,
> get_refs_via_connect,
> fetch_refs_via_pack,Up to this point I think I understand the change. We gain one new trait for each transport, many of the transport cannot run fetch without first seeing the advertisement, some are OK, so we have 0 or 1 in these vtables as appropriately.
Show 13 quoted lines
> @@ -1224,6 +1227,15 @@ int transport_fetch_refs(struct transport *transport, struct ref *refs) > struct ref **heads = NULL; > struct ref *rm; > > + if (!transport->vtable->fetch_without_list) > + /* > + * Some transports (e.g. the built-in bundle transport and the > + * transport helper interface) do not work when fetching is > + * done immediately after transport creation. List the remote > + * refs anyway (if not already listed) as a workaround. > + */ > + transport_get_remote_refs(transport, NULL); > +
But this I do not quite understand. It looks saying "when asked to fetch, if the transport does not allow us to do so without first getting the advertisement, lazily do that", and that may be a good thing to do, but then aren't the current set of callers already calling transport-get-remote-refs elsewhere before they call transport-fetch-refs? IOW, I would have expected to see a matching removal, or at least a code that turns an unconditional call to get-remote-refs to a conditional one that is done only for the transport that lacks the capability, or something along that line.
... ah, do you mean that this is not a new feature, but is a bugfix for some callers that are not calling get-remote-refs before calling fetch-refs, and the bit is to work around the fact that some transport not just can function without get-remote-refs first but do not want to call it?
IOW, I am a bit confused by this comment (copied from an earlier part)
> + /** > + * This transport supports the fetch() function being called > + * without get_refs_list() first being called. > + */
Shouldn't it read more like "this transport does not want its get-refs-list called when fetch-refs is done"?
I dunno.
> for (rm = refs; rm; rm = rm->next) {
> nr_refs++;
> if (rm->peer_ref &&