From 48bc984c76b21430f719fbf34ed4da30247236d4 Mon Sep 17 00:00:00 2001
From: Kenny Levinsen <kl@kl.wtf>
Date: Wed, 15 Nov 2023 23:19:55 +0100
Subject: [PATCH] input/keyboard: Skip configure on same config

sway_keyboard_configure does a lot of keyboard setup, including loading
the keymap (possibly twice in case of fallback), serializing both old
and new keymap to compare them with a strcmp, and updating state that
leads to events for all related clients.

This function is called a lot - output configuration will call it
n_outputs x n_keyboard_devices times. Avoid doing work if the
configuration for a particular keyboard has not actually changed.
---
 include/sway/config.h         | 2 ++
 include/sway/input/keyboard.h | 2 ++
 sway/config/input.c           | 5 +++++
 sway/input/keyboard.c         | 7 +++++++
 4 files changed, 16 insertions(+)

diff --git a/include/sway/config.h b/include/sway/config.h
index f9da19675..a754ae746 100644
--- a/include/sway/config.h
+++ b/include/sway/config.h
@@ -189,6 +189,8 @@ struct input_config {
 
 	bool capturable;
 	struct wlr_box region;
+
+	uint64_t seq_id;
 };
 
 /**
diff --git a/include/sway/input/keyboard.h b/include/sway/input/keyboard.h
index 571d9e6fa..9b2687bef 100644
--- a/include/sway/input/keyboard.h
+++ b/include/sway/input/keyboard.h
@@ -69,6 +69,8 @@ struct sway_keyboard {
 
 	struct wl_event_source *key_repeat_source;
 	struct sway_binding *repeat_binding;
+
+	uint64_t last_input_config;
 };
 
 struct sway_keyboard_group {
diff --git a/sway/config/input.c b/sway/config/input.c
index 44c2be289..4ce1b9503 100644
--- a/sway/config/input.c
+++ b/sway/config/input.c
@@ -6,12 +6,16 @@
 #include "sway/input/keyboard.h"
 #include "log.h"
 
+static uint64_t input_config_sequence = 0;
+
 struct input_config *new_input_config(const char* identifier) {
 	struct input_config *input = calloc(1, sizeof(struct input_config));
 	if (!input) {
 		sway_log(SWAY_DEBUG, "Unable to allocate input config");
 		return NULL;
 	}
+	input->seq_id = input_config_sequence++;
+
 	sway_log(SWAY_DEBUG, "new_input_config(%s)", identifier);
 	if (!(input->identifier = strdup(identifier))) {
 		free(input);
@@ -182,6 +186,7 @@ void merge_input_config(struct input_config *dst, struct input_config *src) {
 
 		tool_merge_outer:;
 	}
+	dst->seq_id = input_config_sequence++;
 }
 
 static bool validate_xkb_merge(struct input_config *dest,
diff --git a/sway/input/keyboard.c b/sway/input/keyboard.c
index 8927287fb..fc45746f0 100644
--- a/sway/input/keyboard.c
+++ b/sway/input/keyboard.c
@@ -969,6 +969,11 @@ void sway_keyboard_configure(struct sway_keyboard *keyboard) {
 		return;
 	}
 
+	if (!config->reloading && keyboard->last_input_config == input_config->seq_id) {
+		// We have been here before, so bail early
+		return;
+	}
+
 	struct xkb_keymap *keymap = sway_keyboard_compile_keymap(input_config, NULL);
 	if (!keymap) {
 		sway_log(SWAY_ERROR, "Failed to compile keymap. Attempting defaults");
@@ -1068,6 +1073,8 @@ void sway_keyboard_configure(struct sway_keyboard *keyboard) {
 		&keyboard->keyboard_modifiers);
 	keyboard->keyboard_modifiers.notify = handle_keyboard_modifiers;
 
+	keyboard->last_input_config = input_config->seq_id;
+
 	if (keymap_changed) {
 		ipc_event_input("xkb_keymap",
 			keyboard->seat_device->input_device);