[PATCH v6 6/6] object-name: re-use "struct strbuf" in show_ambiguous_object()

["Ævar Arnfjörð Bjarmason" <avarab@gmail.com>]

Reduce the allocations done by show_ambiguous_object() by moving the
"desc" strbuf into the "struct ambiguous_output" introduced in the
preceding commit.

This doesn't matter for optimization purposes, but since we're
accumulating a "struct strbuf advice" anyway let's follow that pattern
and add a "struct strbuf sb", we can then strbuf_reset() it rather
than calling strbuf_release() for each call to
show_ambiguous_object().

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---
 object-name.c | 21 ++++++++++++---------
 1 file changed, 12 insertions(+), 9 deletions(-)

diff --git a/object-name.c b/object-name.c
index 743d272800d..2d60e5177d3 100644
--- a/object-name.c
+++ b/object-name.c
@@ -354,6 +354,7 @@ static int init_object_disambiguation(struct repository *r,
 struct ambiguous_output {
 	const struct disambiguate_state *ds;
 	struct strbuf advice;
+	struct strbuf sb;
 };
 
 static int show_ambiguous_object(const struct object_id *oid, void *data)
@@ -361,7 +362,7 @@ static int show_ambiguous_object(const struct object_id *oid, void *data)
 	struct ambiguous_output *state = data;
 	const struct disambiguate_state *ds = state->ds;
 	struct strbuf *advice = &state->advice;
-	struct strbuf desc = STRBUF_INIT;
+	struct strbuf *sb = &state->sb;
 	int type;
 	const char *hash;
 
@@ -377,7 +378,7 @@ static int show_ambiguous_object(const struct object_id *oid, void *data)
 		 * output shown when we cannot look up or parse the
 		 * object in question. E.g. "deadbeef [bad object]".
 		 */
-		strbuf_addf(&desc, _("%s [bad object]"), hash);
+		strbuf_addf(sb, _("%s [bad object]"), hash);
 		goto out;
 	}
 
@@ -402,8 +403,8 @@ static int show_ambiguous_object(const struct object_id *oid, void *data)
 		 *
 		 *    "deadbeef commit 2021-01-01 - Some Commit Message"
 		 */
-		strbuf_addf(&desc, _("%s commit %s - %s"),
-			    hash, date.buf, msg.buf);
+		strbuf_addf(sb, _("%s commit %s - %s"), hash, date.buf,
+			    msg.buf);
 
 		strbuf_release(&date);
 		strbuf_release(&msg);
@@ -427,7 +428,7 @@ static int show_ambiguous_object(const struct object_id *oid, void *data)
 		 * object.c, it should (hopefully) already be
 		 * translated.
 		 */
-		strbuf_addf(&desc, _("%s tag %s - %s"), hash,
+		strbuf_addf(sb, _("%s tag %s - %s"), hash,
 			    show_date(tag_date, 0, DATE_MODE(SHORT)),
 			    tag_tag);
 	} else if (type == OBJ_TREE) {
@@ -435,13 +436,13 @@ static int show_ambiguous_object(const struct object_id *oid, void *data)
 		 * TRANSLATORS: This is a line of ambiguous <type>
 		 * object output. E.g. "deadbeef tree".
 		 */
-		strbuf_addf(&desc, _("%s tree"), hash);
+		strbuf_addf(sb, _("%s tree"), hash);
 	} else if (type == OBJ_BLOB) {
 		/*
 		 * TRANSLATORS: This is a line of ambiguous <type>
 		 * object output. E.g. "deadbeef blob".
 		 */
-		strbuf_addf(&desc, _("%s blob"), hash);
+		strbuf_addf(sb, _("%s blob"), hash);
 	}
 
 
@@ -450,9 +451,9 @@ static int show_ambiguous_object(const struct object_id *oid, void *data)
 	 * TRANSLATORS: This is line item of ambiguous object output
 	 * from describe_ambiguous_object() above.
 	 */
-	strbuf_addf(advice, _("  %s\n"), desc.buf);
+	strbuf_addf(advice, _("  %s\n"), sb->buf);
 
-	strbuf_release(&desc);
+	strbuf_reset(sb);
 	return 0;
 }
 
@@ -551,6 +552,7 @@ static enum get_oid_result get_short_oid(struct repository *r,
 		struct oid_array collect = OID_ARRAY_INIT;
 		struct ambiguous_output out = {
 			.ds = &ds,
+			.sb = STRBUF_INIT,
 			.advice = STRBUF_INIT,
 		};
 
@@ -580,6 +582,7 @@ static enum get_oid_result get_short_oid(struct repository *r,
 
 		oid_array_clear(&collect);
 		strbuf_release(&out.advice);
+		strbuf_release(&out.sb);
 	}
 
 	return status;
-- 
2.34.1.1257.g2af47340c7b