From: Jeff King <peff@peff.net>
Date: Thu, 22 Jan 2026 19:07:51 GMT
Subject: Re: [PATCH v27 2/2] status: add status.compareBranches config for multiple branch comparisons
Message-ID: <20260122190751.GA2098026@coredump.intra.peff.net>
In-Reply-To: <0993420fc1185ec4a907a8c3bb52ca965e720c54.1769096240.git.gitgitgadget@gmail.com>

On Thu, Jan 22, 2026 at 03:37:20PM +0000, Harald Nordgren via GitGitGadget wrote:

> +		if (string_list_has_string(&processed_refs, full_ref)) {
> +			free(full_ref);
> +			continue;
> +		}
> +		string_list_insert(&processed_refs, full_ref);

Using a string list like this is quadratic. It probably doesn't matter
too much here since we wouldn't expect the list of configured branches
to be very long, though. But a strset is probably the better tool, like
the diff below (note that its "add" can be used as a single operation to
insert and check).

I don't know if it's worth re-rolling for this or not. I doubt anybody
would hit it in practice, but I'd be more concerned about people
auditing for accidentally-quadratic uses of string_list and stumbling
upon it.

-Peff

diff --git a/remote.c b/remote.c
index e256cc9b81..1071a23567 100644
--- a/remote.c
+++ b/remote.c
@@ -2339,7 +2339,7 @@ int format_tracking_info(struct branch *branch, struct strbuf *sb,
 {
 	char *compare_branches = NULL;
 	struct string_list branches = STRING_LIST_INIT_DUP;
-	struct string_list processed_refs = STRING_LIST_INIT_DUP;
+	struct strset processed_refs = STRSET_INIT;
 	int reported = 0;
 	size_t i;
 	const char *upstream_ref;
@@ -2370,11 +2370,10 @@ int format_tracking_info(struct branch *branch, struct strbuf *sb,
 		if (!full_ref)
 			continue;
 
-		if (string_list_has_string(&processed_refs, full_ref)) {
+		if (!strset_add(&processed_refs, full_ref)) {
 			free(full_ref);
 			continue;
 		}
-		string_list_insert(&processed_refs, full_ref);
 
 		short_ref = refs_shorten_unambiguous_ref(
 			get_main_ref_store(the_repository), full_ref, 0);
@@ -2421,7 +2420,7 @@ int format_tracking_info(struct branch *branch, struct strbuf *sb,
 	}
 
 	string_list_clear(&branches, 0);
-	string_list_clear(&processed_refs, 0);
+	strset_clear(&processed_refs);
 	free(compare_branches);
 	return reported;
 }