From 0353c6881890db1302f0f1bdf85c6076eed61113 Mon Sep 17 00:00:00 2001
From: Junio C Hamano <gitster@pobox.com>
Date: Mon, 16 May 2022 16:53:40 -0700
Subject: [PATCH] fetch: do not run a redundant fetch from submodule
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>
---
builtin/fetch.c | 16 +++++++++++++++-
t/t5526-fetch-submodules.sh | 27 +++++++++++++++++++++++++++
2 files changed, 42 insertions(+), 1 deletion(-)
diff --git a/builtin/fetch.c b/builtin/fetch.c
index e3791f09ed..8b15c40bb2 100644
--- a/builtin/fetch.c
+++ b/builtin/fetch.c
@@ -2187,6 +2187,10 @@ int cmd_fetch(int argc, const char **argv, const char *prefix)
else if (argc > 1)
die(_("fetch --all does not make sense with refspecs"));
(void) for_each_remote(get_one_remote_for_fetch, &list);
+
+ /* do not do fetch_multiple() of one */
+ if (list.nr == 1)
+ remote = remote_get(list.items[0].string);
} else if (argc == 0) {
/* No arguments -- use default remote */
remote = remote_get(NULL);
@@ -2261,7 +2265,17 @@ int cmd_fetch(int argc, const char **argv, const char *prefix)
result = fetch_multiple(&list, max_children);
}
- if (!result && (recurse_submodules != RECURSE_SUBMODULES_OFF)) {
+
+ /*
+ * This is only needed after fetch_one(), which does not fetch
+ * submodules by itself.
+ *
+ * When we fetch from multiple remotes, fetch_multiple() has
+ * already updated submodules to grab commits necessary for
+ * the fetched history from each remote, so there is no need
+ * to fetch submodules from here.
+ */
+ if (!result && remote && (recurse_submodules != RECURSE_SUBMODULES_OFF)) {
struct strvec options = STRVEC_INIT;
int max_children = max_jobs;
diff --git a/t/t5526-fetch-submodules.sh b/t/t5526-fetch-submodules.sh
index 43dada8544..a301b56db8 100755
--- a/t/t5526-fetch-submodules.sh
+++ b/t/t5526-fetch-submodules.sh
@@ -1125,4 +1125,31 @@ test_expect_success 'fetch --recurse-submodules updates name-conflicted, unpopul
)
'
+test_expect_success 'fetch --all with --recurse-submodules' '
+ test_when_finished "rm -fr src_clone" &&
+ git clone --recurse-submodules src src_clone &&
+ (
+ cd src_clone &&
+ git config submodule.recurse true &&
+ git config fetch.parallel 0 &&
+ git fetch --all 2>../fetch-log
+ ) &&
+ grep "^Fetching submodule sub$" fetch-log >fetch-subs &&
+ test_line_count = 1 fetch-subs
+'
+
+test_expect_success 'fetch --all with --recurse-submodules with multiple' '
+ test_when_finished "rm -fr src_clone" &&
+ git clone --recurse-submodules src src_clone &&
+ (
+ cd src_clone &&
+ git remote add secondary ../src &&
+ git config submodule.recurse true &&
+ git config fetch.parallel 0 &&
+ git fetch --all 2>../fetch-log
+ ) &&
+ grep "Fetching submodule sub" fetch-log >fetch-subs &&
+ test_line_count = 2 fetch-subs
+'
+
test_done