sha1_file.c: the global packed_git variable static to the filesz/packed-git-static

This is a first step in making the codebase thread-safe.  By and
large, the operations which might benefit from threading are those
that work with pack files (e.g., checkout, blame), so the focus of
this patch is stop leaking the global list of pack files outside of
sha1_file.c.

The next step will be to control access to the list of pack files
with a mutex.  However, that alone is not enough to make pack file
access thread safe.  Even in a read-only operation, the window list
associated with each pack file will need to be controlled.
Additionally, the global counters in sha1_file.c will need to be
controlled.

This patch is a pure refactor with no functional changes, so it
shouldn't require any additional tests.  Adding the actual locks
will be a functional change, and will require additional tests.

[jc: with minimul style fixes before a full review]

Signed-off-by: Stefan Zager <szager@chromium.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 15 insertions, 3 deletions

diff --git a/sha1_name.c b/sha1_name.c
index a5578f718e..c1f24a1b43 100644
--- a/sha1_name.c
+++ b/sha1_name.c
@@ -176,14 +176,26 @@ static void unique_in_pack(int len,
 	}
 }
 
+struct disambiguate_data {
+	int len;
+	const unsigned char *bin_pfx;
+	struct disambiguate_state *ds;
+};
+
+static int find_short_packed_object_fn(struct packed_git *p, void *data)
+{
+	struct disambiguate_data *d = (struct disambiguate_data *) data;
+	unique_in_pack(d->len, d->bin_pfx, p, d->ds);
+	return 0;
+}
+
 static void find_short_packed_object(int len, const unsigned char *bin_pfx,
 				     struct disambiguate_state *ds)
 {
-	struct packed_git *p;
+	struct disambiguate_data d = {len, bin_pfx, ds};
 
 	prepare_packed_git();
-	for (p = packed_git; p && !ds->ambiguous; p = p->next)
-		unique_in_pack(len, bin_pfx, p, ds);
+	foreach_packed_git(find_short_packed_object_fn, NULL, &d);
 }
 
 #define SHORT_NAME_NOT_FOUND (-1)