When we want to look up a submodule ref, we use
get_ref_cache(path) to find or auto-create its ref cache.
But if we feed a path that isn't actually a git repository,
we blindly create the ref cache, and then may die deeper in
the code when we try to access it. This is a problem because
many callers speculatively feed us a path that looks vaguely
like a repository, and expect us to tell them when it is
not.
This patch teaches resolve_gitlink_ref to reject
non-repository paths without creating a ref_cache. This
avoids the die(), and also performs better if you have a
large number of these faux-submodule directories (because
the ref_cache lookup is linear, under the assumption that
there won't be a large number of submodules).
To accomplish this, we also break get_ref_cache into two
pieces: the lookup and auto-creation (the latter is lumped
into create_ref_cache). This lets us first cheaply ask our
cache "is it a submodule we know about?" If so, we can avoid
repeating our filesystem lookup. So lookups of real
submodules are not penalized; they examine the submodule's
.git directory only once.
The test in t3000 demonstrates a case where this improves
correctness (we used to just die). The new perf case in
p7300 shows off the speed improvement in an admittedly
pathological repository:
Test HEAD^ HEAD
----------------------------------------------------------------
7300.4: ls-files -o 66.97(66.15+0.87) 0.33(0.08+0.24) -99.5%
Signed-off-by: Jeff King <peff@xxxxxxxx>
---
refs/files-backend.c | 46 ++++++++++++++++++++++++++++++++--------------
t/perf/p7300-clean.sh | 4 ++++
t/t3000-ls-files-others.sh | 7 +++++++
3 files changed, 43 insertions(+), 14 deletions(-)
diff --git a/refs/files-backend.c b/refs/files-backend.c
index c648b5e..3a27f27 100644
--- a/refs/files-backend.c
+++ b/refs/files-backend.c
@@ -933,6 +933,10 @@ static void clear_loose_ref_cache(struct ref_cache *refs)
}
}
+/*
+ * Create a new submodule ref cache and add it to the internal
+ * set of caches.
+ */
static struct ref_cache *create_ref_cache(const char *submodule)
{
int len;
@@ -942,16 +946,12 @@ static struct ref_cache *create_ref_cache(const char *submodule)
len = strlen(submodule) + 1;
refs = xcalloc(1, sizeof(struct ref_cache) + len);
memcpy(refs->name, submodule, len);
+ refs->next = submodule_ref_caches;
+ submodule_ref_caches = refs;
return refs;
}
-/*
- * Return a pointer to a ref_cache for the specified submodule. For
- * the main repository, use submodule==NULL. The returned structure
- * will be allocated and initialized but not necessarily populated; it
- * should not be freed.
- */
-static struct ref_cache *get_ref_cache(const char *submodule)
+static struct ref_cache *lookup_ref_cache(const char *submodule)
{
struct ref_cache *refs;
@@ -961,10 +961,20 @@ static struct ref_cache *get_ref_cache(const char *submodule)
for (refs = submodule_ref_caches; refs; refs = refs->next)
if (!strcmp(submodule, refs->name))
return refs;
+ return NULL;
+}
- refs = create_ref_cache(submodule);
- refs->next = submodule_ref_caches;
- submodule_ref_caches = refs;
+/*
+ * Return a pointer to a ref_cache for the specified submodule. For
+ * the main repository, use submodule==NULL. The returned structure
+ * will be allocated and initialized but not necessarily populated; it
+ * should not be freed.
+ */
+static struct ref_cache *get_ref_cache(const char *submodule)
+{
+ struct ref_cache *refs = lookup_ref_cache(submodule);
+ if (!refs)
+ refs = create_ref_cache(submodule);
return refs;
}
@@ -1336,16 +1346,24 @@ static int resolve_gitlink_ref_recursive(struct ref_cache *refs,
int resolve_gitlink_ref(const char *path, const char *refname, unsigned char *sha1)
{
int len = strlen(path), retval;
- char *submodule;
+ struct strbuf submodule = STRBUF_INIT;
struct ref_cache *refs;
while (len && path[len-1] == '/')
len--;
if (!len)
return -1;
- submodule = xstrndup(path, len);
- refs = get_ref_cache(submodule);
- free(submodule);
+
+ strbuf_add(&submodule, path, len);
+ refs = lookup_ref_cache(submodule.buf);
+ if (!refs) {
+ if (!is_nonbare_repository_dir(&submodule)) {
+ strbuf_release(&submodule);
+ return -1;
+ }
+ refs = create_ref_cache(submodule.buf);
+ }
+ strbuf_release(&submodule);
retval = resolve_gitlink_ref_recursive(refs, refname, sha1, 0);
return retval;
diff --git a/t/perf/p7300-clean.sh b/t/perf/p7300-clean.sh
index ec94cdd..7c1888a 100755
--- a/t/perf/p7300-clean.sh
+++ b/t/perf/p7300-clean.sh
@@ -28,4 +28,8 @@ test_perf 'clean many untracked sub dirs, ignore nested git' '
git clean -n -q -f -f -d 100000_sub_dirs/
'
+test_perf 'ls-files -o' '
+ git ls-files -o
+'
+
test_done
diff --git a/t/t3000-ls-files-others.sh b/t/t3000-ls-files-others.sh
index 88be904..c525656 100755
--- a/t/t3000-ls-files-others.sh
+++ b/t/t3000-ls-files-others.sh
@@ -65,6 +65,13 @@ test_expect_success '--no-empty-directory hides empty directory' '
test_cmp expected3 output
'
+test_expect_success 'ls-files --others handles non-submodule .git' '
+ mkdir not-a-submodule &&
+ echo foo >not-a-submodule/.git &&
+ git ls-files -o >output &&
+ test_cmp expected1 output
+'
+
test_expect_success SYMLINKS 'ls-files --others with symlinked submodule' '
git init super &&
git init sub &&
--
2.7.0.384.gae54cb4
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