[PATCH v4 3/7] gc: refactor a "call me once" pattern

["Ævar Arnfjörð Bjarmason" <avarab@gmail.com>]

Change an idiom we're using to ensure that gc_before_repack() only
does work once (see 62aad1849f ("gc --auto: do not lock refs in the
background", 2014-05-25)) to be more obvious.

Nothing except this function cares about the "pack_refs" and
"prune_reflogs" variables, so let's not leave the reader wondering if
they're being zero'd out for later use somewhere else.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---
 builtin/gc.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/builtin/gc.c b/builtin/gc.c
index 733bd7bdf4..ae716a00d4 100644
--- a/builtin/gc.c
+++ b/builtin/gc.c
@@ -489,14 +489,20 @@ static int report_last_gc_error(void)
 
 static void gc_before_repack(void)
 {
+	/*
+	 * We may be called twice, as both the pre- and
+	 * post-daemonized phases will call us, but running these
+	 * commands more than once is pointless and wasteful.
+	 */
+	static int done = 0;
+	if (done++)
+		return;
+
 	if (pack_refs && run_command_v_opt(pack_refs_cmd.argv, RUN_GIT_CMD))
 		die(FAILED_RUN, pack_refs_cmd.argv[0]);
 
 	if (prune_reflogs && run_command_v_opt(reflog.argv, RUN_GIT_CMD))
 		die(FAILED_RUN, reflog.argv[0]);
-
-	pack_refs = 0;
-	prune_reflogs = 0;
 }
 
 int cmd_gc(int argc, const char **argv, const char *prefix)
-- 
2.21.0.392.gf8f6787159e