Subject: Re: Git is not scalable with too many refs/*

From: René Scharfe <[email-masked]>
Date: Thu, 29 Sep 2011 20:27:43 +0200

Am 29.09.2011 04:19, schrieb Julian Phillips:
> Does the following help?
> 
> diff --git a/builtin/checkout.c b/builtin/checkout.c
> index 5e356a6..f0f4ca1 100644
> --- a/builtin/checkout.c
> +++ b/builtin/checkout.c
> @@ -605,7 +605,7 @@ static int add_one_ref_to_rev_list_arg(const char
> *refname,
>                                        int flags,
>                                        void *cb_data)
>  {
> -       add_one_rev_list_arg(cb_data, refname);
> +       add_one_rev_list_arg(cb_data, strdup(sha1_to_hex(sha1)));
>         return 0;
>  }

Hmm.  Can we get rid of the multiple ref lookups fixed by the above
*and* the overhead of dealing with a textual argument list at the same
time by calling add_pending_object directly, like this?  (Factoring
out add_pending_sha1 should be a separate patch..)

René

---
 builtin/checkout.c |   39 ++++++++++++---------------------------
 revision.c         |   11 ++++++++---
 revision.h         |    1 +
 3 files changed, 21 insertions(+), 30 deletions(-)

diff --git a/builtin/checkout.c b/builtin/checkout.c
index 5e356a6..84e0cdc 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -588,24 +588,11 @@ static void update_refs_for_switch(struct checkout_opts *opts,
 		report_tracking(new);
 }
 
-struct rev_list_args {
-	int argc;
-	int alloc;
-	const char **argv;
-};
-
-static void add_one_rev_list_arg(struct rev_list_args *args, const char *s)
-{
-	ALLOC_GROW(args->argv, args->argc + 1, args->alloc);
-	args->argv[args->argc++] = s;
-}
-
-static int add_one_ref_to_rev_list_arg(const char *refname,
-				       const unsigned char *sha1,
-				       int flags,
-				       void *cb_data)
+static int add_pending_uninteresting_ref(const char *refname,
+					 const unsigned char *sha1,
+					 int flags, void *cb_data)
 {
-	add_one_rev_list_arg(cb_data, refname);
+	add_pending_sha1(cb_data, refname, sha1, flags | UNINTERESTING);
 	return 0;
 }
 
@@ -685,19 +672,17 @@ static void suggest_reattach(struct commit *commit, struct rev_info *revs)
  */
 static void orphaned_commit_warning(struct commit *commit)
 {
-	struct rev_list_args args = { 0, 0, NULL };
 	struct rev_info revs;
-
-	add_one_rev_list_arg(&args, "(internal)");
-	add_one_rev_list_arg(&args, sha1_to_hex(commit->object.sha1));
-	add_one_rev_list_arg(&args, "--not");
-	for_each_ref(add_one_ref_to_rev_list_arg, &args);
-	add_one_rev_list_arg(&args, "--");
-	add_one_rev_list_arg(&args, NULL);
+	struct object *object = &commit->object;
 
 	init_revisions(&revs, NULL);
-	if (setup_revisions(args.argc - 1, args.argv, &revs, NULL) != 1)
-		die(_("internal error: only -- alone should have been left"));
+	setup_revisions(0, NULL, &revs, NULL);
+
+	object->flags &= ~UNINTERESTING;
+	add_pending_object(&revs, object, sha1_to_hex(object->sha1));
+
+	for_each_ref(add_pending_uninteresting_ref, &revs);
+
 	if (prepare_revision_walk(&revs))
 		die(_("internal error in revision walk"));
 	if (!(commit->object.flags & UNINTERESTING))
diff --git a/revision.c b/revision.c
index c46cfaa..2e8aa33 100644
--- a/revision.c
+++ b/revision.c
@@ -185,6 +185,13 @@ static struct object *get_reference(struct rev_info *revs, const char *name, con
 	return object;
 }
 
+void add_pending_sha1(struct rev_info *revs, const char *name,
+		      const unsigned char *sha1, unsigned int flags)
+{
+	struct object *object = get_reference(revs, name, sha1, flags);
+	add_pending_object(revs, object, name);
+}
+
 static struct commit *handle_commit(struct rev_info *revs, struct object *object, const char *name)
 {
 	unsigned long flags = object->flags;
@@ -832,9 +839,7 @@ struct all_refs_cb {
 static int handle_one_ref(const char *path, const unsigned char *sha1, int flag, void *cb_data)
 {
 	struct all_refs_cb *cb = cb_data;
-	struct object *object = get_reference(cb->all_revs, path, sha1,
-					      cb->all_flags);
-	add_pending_object(cb->all_revs, object, path);
+	add_pending_sha1(cb->all_revs, path, sha1, cb->all_flags);
 	return 0;
 }
 
diff --git a/revision.h b/revision.h
index 3d64ada..4541265 100644
--- a/revision.h
+++ b/revision.h
@@ -191,6 +191,7 @@ extern void add_object(struct object *obj,
 		       const char *name);
 
 extern void add_pending_object(struct rev_info *revs, struct object *obj, const char *name);
+extern void add_pending_sha1(struct rev_info *revs, const char *name, const unsigned char *sha1, unsigned int flags);
 
 extern void add_head_to_pending(struct rev_info *);
 
-- 
1.7.7.rc1