degesch: optimize prompt changes

We used to do lots of unnecessary redisplays.

1 files changed, 12 insertions, 2 deletions

diff --git a/degesch.c b/degesch.c
index 436e9eb..f4deab3 100644
--- a/degesch.c
+++ b/degesch.c
@@ -5056,6 +5056,16 @@ make_prompt (struct app_context *ctx, struct str *output)
 }
 
 static void
+input_maybe_set_prompt (struct input *self, char *new_prompt)
+{
+	// Redisplay can be an expensive operation
+	if (self->prompt && !strcmp (new_prompt, self->prompt))
+		free (new_prompt);
+	else
+		input_set_prompt (self, new_prompt);
+}
+
+static void
 refresh_prompt (struct app_context *ctx)
 {
 	bool have_attributes = !!get_attribute_printer (stdout);
@@ -5070,7 +5080,7 @@ refresh_prompt (struct app_context *ctx)
 	if (have_attributes)
 	{
 		// XXX: to be completely correct, we should use tputs, but we cannot
-		input_set_prompt (&ctx->input, xstrdup_printf ("%c%s%c%s%c%s%c",
+		input_maybe_set_prompt (&ctx->input, xstrdup_printf ("%c%s%c%s%c%s%c",
 			INPUT_START_IGNORE, ctx->attrs[ATTR_PROMPT],
 			INPUT_END_IGNORE,
 			localized,
@@ -5079,7 +5089,7 @@ refresh_prompt (struct app_context *ctx)
 		free (localized);
 	}
 	else
-		input_set_prompt (&ctx->input, localized);
+		input_maybe_set_prompt (&ctx->input, localized);
 }
 
 // --- Helpers -----------------------------------------------------------------