commit 799728f7aeb4842a6458eccfc51df84e5cbc40d0
from: Stefan Sperling <stsp@stsp.name>
date: Thu Nov 21 11:00:05 2024 UTC

gotwebd: improve performance of repository age calculations

Instead of sorting refs by name and then hunting for the youngest
commits in that list, obtain an appropriately sorted list via
got_ref_cmp_by_commit_timestamp_descending and then pick the first
ref from this list.

And in the case were we already know which ref to check, just open
this ref directly instead of listing all the refs.

Easier to read and should improve performance in both cases.

ok op, jamsek

commit - ece731b025b35fd112ea1faebfabb163b61aacbe
commit + 799728f7aeb4842a6458eccfc51df84e5cbc40d0
blob - f4a93f9f22c2a2ae93a2bf822794bade8af45b6c
blob + e6b67696b6074e0499b029da5f51a883bf9c1e89
--- gotwebd/got_operations.c
+++ gotwebd/got_operations.c
@@ -116,59 +116,82 @@ got_get_repo_owner(char **owner, struct request *c)
 	return NULL;
 }
 
-const struct got_error *
-got_get_repo_age(time_t *repo_age, struct request *c, const char *refname)
+static const struct got_error *
+get_ref_commit_timestamp(time_t *timestamp,
+    struct got_reference *ref, struct got_repository *repo)
 {
-	const struct got_error *error = NULL;
-	struct transport *t = c->t;
-	struct got_repository *repo = t->repo;
+	const struct got_error *error;
+	struct got_object_id *id = NULL;
+	int obj_type;
 	struct got_commit_object *commit = NULL;
-	struct got_reflist_head refs;
-	struct got_reflist_entry *re;
-	time_t committer_time = 0, cmp_time = 0;
 
-	TAILQ_INIT(&refs);
+	/* We might have a cached timestamp available. */
+	*timestamp = got_ref_get_cached_committer_time(ref);
+	if (*timestamp != 0)
+		return NULL;
 
-	*repo_age = 0;
+	error = got_ref_resolve(&id, repo, ref);
+	if (error)
+		return error;
 
-	error = got_ref_list(&refs, repo, "refs/heads",
-	    got_ref_cmp_by_name, NULL);
+	error = got_object_get_type(&obj_type, repo, id);
+	if (error || obj_type != GOT_OBJ_TYPE_COMMIT)
+		goto done;
+
+	error = got_object_open_as_commit(&commit, repo, id);
 	if (error)
 		goto done;
 
-	/*
-	 * Find the youngest branch tip in the repository, or the age of
-	 * the a specific branch tip if a name was provided by the caller.
-	 */
-	TAILQ_FOREACH(re, &refs, entry) {
-		struct got_object_id *id = NULL;
+	*timestamp = got_object_commit_get_committer_time(commit);
+done:
+	free(id);
+	if (commit)
+		got_object_commit_close(commit);
 
-		if (refname && strcmp(got_ref_get_name(re->ref), refname) != 0)
-			continue;
+	return error;
+}
 
-		error = got_ref_resolve(&id, repo, re->ref);
-		if (error)
-			goto done;
-
-		error = got_object_open_as_commit(&commit, repo, id);
-		free(id);
+/*
+ * Find the youngest branch tip in the repository, or the age of
+ * a specific branch tip if a name was provided by the caller.
+ */
+const struct got_error *
+got_get_repo_age(time_t *repo_age, struct request *c, const char *refname)
+{
+	const struct got_error *error = NULL;
+	struct transport *t = c->t;
+	struct got_repository *repo = t->repo;
+
+	*repo_age = 0;
+
+	if (refname) {
+		struct got_reference *ref;
+
+		error = got_ref_open(&ref, repo, refname, 0);
 		if (error)
-			goto done;
+			return error;
 
-		committer_time =
-		    got_object_commit_get_committer_time(commit);
-		got_object_commit_close(commit);
-		if (cmp_time < committer_time)
-			cmp_time = committer_time;
+		error = get_ref_commit_timestamp(repo_age, ref, repo);
+		got_ref_close(ref);
+	} else {
+		struct got_reflist_head refs;
+		struct got_reflist_entry *re;
 
-		if (refname)
-			break;
+		TAILQ_INIT(&refs);
+
+		error = got_ref_list(&refs, repo, "refs/heads",
+		    got_ref_cmp_by_commit_timestamp_descending, repo);
+		if (error)
+			return error;
+
+		re = TAILQ_FIRST(&refs);
+		if (re) {
+			error = get_ref_commit_timestamp(repo_age,
+			    re->ref, repo);
+		}
+		got_ref_list_free(&refs);
 	}
 
-	if (cmp_time != 0)
-		*repo_age = cmp_time;
- done:
-	got_ref_list_free(&refs);
 	return error;
 }
 
blob - 0e987a302c6c21819424c0bbf8c957b06744abd8
blob + 55e4df44b40d37a2a722f120946119046d3edc41
--- include/got_reference.h
+++ include/got_reference.h
@@ -66,6 +66,17 @@ const char *got_ref_get_symref_target(struct got_refer
 time_t got_ref_get_mtime(struct got_reference *);
 
 /*
+ * Get the modification timestamp of the commit pointed at by the
+ * given reference. Will return zero if the commit timestamp is
+ * unknown or if the reference does not point at a commit.
+ *
+ * The cached timestamp will be known after got_ref_list() was called
+ * with either got_ref_cmp_by_commit_timestamp_descending() or
+ * with got_ref_cmp_tags().
+ */
+time_t got_ref_get_cached_committer_time(struct got_reference *);
+
+/*
  * Create a duplicate copy of a reference.
  * The caller must dispose of this copy with got_ref_close().
  */
blob - 3b728f8e2874054c0698accbbe24e51d69d93929
blob + b79065ff8ad9f1c2ab6d0c59c7cbb5c02c6b2467
--- lib/reference.c
+++ lib/reference.c
@@ -642,6 +642,12 @@ time_t
 got_ref_get_mtime(struct got_reference *ref)
 {
 	return ref->mtime;
+}
+
+time_t
+got_ref_get_cached_committer_time(struct got_reference *ref)
+{
+	return ref->committer_time;
 }
 
 const struct got_error *