When 7dce19d3 (fetch/pull: Add the --recurse-submodules option,
2010-11-12) introduced the "--recurse-submodule" option, the
approach taken was to perform fetches in submodules only once, after
all the main fetching (it may usually be a fetch from a single
remote, but it could be fetching from a group of remotes using
fetch_multiple()) succeeded. Later we added "--all" to fetch from
all defined remotes, which complicated things even more.
If your project has a submodule, and you try to run "git fetch
--recurse-submodule --all", you'd see a fetch for the top-level,
which invokes another fetch for the submodule, followed by another
fetch for the same submodule. All but the last fetch for the
submodule come from a "git fetch --recurse-submodules" subprocess
that is spawned via the fetch_multiple() interface for the remotes,
and the last fetch comes from the code at the end.
Because recursive fetching from submodules is done in each fetch for
the top-level in fetch_multiple(), the last fetch in the submodule
is redundant. It only matters when fetch_one() interacts with a
single remote at the top-level.
While we are at it, there is one optimization that exists in dealing
with a group of remote, but is missing when "--all" is used. In the
former, when the group turns out to be a group of one, instead of
spawning "git fetch" as a subprocess via the fetch_multiple()
interface, we use the normal fetch_one() code path. Do the same
when handing "--all", if it turns out that we have only one remote
defined.
Reviewed-by: Glen Choo <chooglen@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
0353c68818