[PATCH 21/23] midx: prevent duplicate packfile loads

[Derrick Stolee <stolee@gmail.com>]

If the multi-pack-index contains a packfile, then we do not need to add
that packfile to the packed_git linked list or the MRU list.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
---
 midx.c     | 23 +++++++++++++++++++++++
 midx.h     |  1 +
 packfile.c |  7 +++++++
 3 files changed, 31 insertions(+)

diff --git a/midx.c b/midx.c
index 388d79b7d9..3242646fe0 100644
--- a/midx.c
+++ b/midx.c
@@ -278,6 +278,29 @@ int fill_midx_entry(const struct object_id *oid, struct pack_entry *e, struct mi
 	return nth_midxed_pack_entry(m, e, pos);
 }
 
+int midx_contains_pack(struct midxed_git *m, const char *idx_name)
+{
+	uint32_t first = 0, last = m->num_packs;
+
+	while (first < last) {
+		uint32_t mid = first + (last - first) / 2;
+		const char *current;
+		int cmp;
+
+		current = m->pack_names[mid];
+		cmp = strcmp(idx_name, current);
+		if (!cmp)
+			return 1;
+		if (cmp > 0) {
+			first = mid + 1;
+			continue;
+		}
+		last = mid;
+	}
+
+	return 0;
+}
+
 int prepare_midxed_git_one(struct repository *r, const char *object_dir)
 {
 	struct midxed_git *m = r->objects->midxed_git;
diff --git a/midx.h b/midx.h
index 497bdcc77c..c1db58d8c4 100644
--- a/midx.h
+++ b/midx.h
@@ -13,6 +13,7 @@ struct object_id *nth_midxed_object_oid(struct object_id *oid,
 					struct midxed_git *m,
 					uint32_t n);
 int fill_midx_entry(const struct object_id *oid, struct pack_entry *e, struct midxed_git *m);
+int midx_contains_pack(struct midxed_git *m, const char *idx_name);
 int prepare_midxed_git_one(struct repository *r, const char *object_dir);
 
 int write_midx_file(const char *object_dir);
diff --git a/packfile.c b/packfile.c
index 059b2aa097..479cb69b9f 100644
--- a/packfile.c
+++ b/packfile.c
@@ -746,6 +746,11 @@ static void prepare_packed_git_one(struct repository *r, char *objdir, int local
 	DIR *dir;
 	struct dirent *de;
 	struct string_list garbage = STRING_LIST_INIT_DUP;
+	struct midxed_git *m = r->objects->midxed_git;
+
+	/* look for the multi-pack-index for this object directory */
+	while (m && strcmp(m->object_dir, objdir))
+		m = m->next;
 
 	strbuf_addstr(&path, objdir);
 	strbuf_addstr(&path, "/pack");
@@ -772,6 +777,8 @@ static void prepare_packed_git_one(struct repository *r, char *objdir, int local
 		base_len = path.len;
 		if (strip_suffix_mem(path.buf, &base_len, ".idx")) {
 			/* Don't reopen a pack we already have. */
+			if (m && midx_contains_pack(m, de->d_name))
+				continue;
 			for (p = r->objects->packed_git; p;
 			     p = p->next) {
 				size_t len;
-- 
2.18.0.rc1