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, 34 insertions, 1 deletions

diff --git a/sha1_file.c b/sha1_file.c
index e13bd2c3ee..6bca45c9f6 100644
--- a/sha1_file.c
+++ b/sha1_file.c
@@ -60,6 +60,7 @@ static struct cached_object empty_tree = {
 	0
 };
 
+static struct packed_git *packed_git;
 static struct packed_git *last_found_pack;
 
 static struct cached_object *find_cached_object(const unsigned char *sha1)
@@ -455,7 +456,6 @@ static unsigned int pack_open_fds;
 static unsigned int pack_max_fds;
 static size_t peak_pack_mapped;
 static size_t pack_mapped;
-struct packed_git *packed_git;
 
 void pack_report(void)
 {
@@ -1078,6 +1078,37 @@ struct packed_git *add_packed_git(const char *path, int path_len, int local)
 	return p;
 }
 
+void foreach_packed_git(packed_git_foreach_fn fn, struct packed_git *hint, void *data)
+{
+	struct packed_git *p;
+	if (hint && ((*fn)(hint, data)))
+		return;
+	for (p = packed_git; p; p = p->next)
+		if (p != hint && (*fn)(p, data))
+			return;
+}
+
+size_t packed_git_count(void)
+{
+	size_t res = 0;
+	struct packed_git *p;
+
+	for (p = packed_git; p; p = p->next)
+		++res;
+	return res;
+}
+
+size_t packed_git_local_count(void)
+{
+	size_t res = 0;
+	struct packed_git *p;
+
+	for (p = packed_git; p; p = p->next)
+		if (p->pack_local)
+			++res;
+	return res;
+}
+
 struct packed_git *parse_pack_index(unsigned char *sha1, const char *idx_path)
 {
 	const char *path = sha1_pack_name(sha1);
@@ -2461,6 +2492,8 @@ struct packed_git *find_sha1_pack(const unsigned char *sha1,
 {
 	struct packed_git *p;
 
+	if (!packs)
+		packs = packed_git;
 	for (p = packs; p; p = p->next) {
 		if (find_pack_entry_one(sha1, p))
 			return p;