commit 5144d22b0c3bcf6611cc36e93a3a859fcc521277
from: Omar Polo <op@omarpolo.com>
date: Wed Jun 14 08:44:44 2023 UTC

gotwebd: simplify got_get_repo_commits(): don't traverse all the commits!

In some cases (e.g. limit=1 for DIFF action) we could end up traversing
all the commits instead of fetching just the one requested.  Needless to
say, this makes the diff page extremely slow.

reported by and ok stsp@

commit - 563ffc1b6d823b71bab79a0a75c67524f3d0f447
commit + 5144d22b0c3bcf6611cc36e93a3a859fcc521277
blob - 3e66b1cc2a7cd11d9c5f6e4d07a2826a420824e2
blob + aba5a591662378d9b7363a6435d153408a11fb87
--- gotwebd/got_operations.c
+++ gotwebd/got_operations.c
@@ -326,7 +326,16 @@ got_get_repo_commits(struct request *c, int limit)
 	struct querystring *qs = t->qs;
 	struct repo_dir *repo_dir = t->repo_dir;
 	char *in_repo_path = NULL, *repo_path = NULL, *file_path = NULL;
-	int chk_next = 0, chk_multi = 0;
+	int chk_next = 0;
+
+	if (limit != 1 || srv->max_commits_display == 1) {
+		/*
+		 * Traverse one commit more than requested to provide
+		 * the next button.
+		 */
+		limit++;
+		chk_next = 1;
+	}
 
 	TAILQ_INIT(&refs);
 
@@ -401,41 +410,21 @@ got_get_repo_commits(struct request *c, int limit)
 		    &refs, &next_id);
 		if (error) {
 			gotweb_free_repo_commit(repo_commit);
+			goto done;
+		}
+
+		if (--limit == 0 && chk_next) {
+			t->more_id = strdup(repo_commit->commit_id);
+			if (t->more_id == NULL)
+				error = got_error_from_errno("strdup");
 			goto done;
 		}
 
 		TAILQ_INSERT_TAIL(&t->repo_commits, repo_commit, entry);
 
-		if (!chk_multi || limit != 1 ||
-		    srv->max_commits_display == 1) {
-			chk_multi = 1;
+		if (limit == 0)
+			goto done;
 
-			/*
-			 * check for one more commit before breaking,
-			 * so we know whether to navigate through briefs
-			 * commits and summary
-			 */
-			if (chk_next && (qs->action == BRIEFS ||
-			    qs->action == COMMITS || qs->action == SUMMARY)) {
-				t->more_id = strdup(repo_commit->commit_id);
-				if (t->more_id == NULL) {
-					error = got_error_from_errno("strdup");
-					goto done;
-				}
-				got_object_commit_close(commit);
-				commit = NULL;
-				TAILQ_REMOVE(&t->repo_commits, repo_commit,
-				    entry);
-				gotweb_free_repo_commit(repo_commit);
-				goto done;
-			}
-		}
-		if (error || (limit && --limit == 0)) {
-			if (qs->file != NULL && *qs->file != '\0')
-				if (chk_multi == 0)
-					break;
-			chk_next = 1;
-		}
 		if (commit) {
 			got_object_commit_close(commit);
 			commit = NULL;