From 704130cc1164604c5b805adf186999269e14c5a5 Mon Sep 17 00:00:00 2001
From: emersion <contact@emersion.fr>
Date: Tue, 30 Jan 2018 14:45:02 +0100
Subject: output: fix performance issues with wlr_output_schedule_frame

---
 backend/wayland/output.c       |  8 +++++++-
 include/wlr/types/wlr_output.h |  2 ++
 types/wlr_output.c             | 22 ++++++++++++++++++----
 3 files changed, 27 insertions(+), 5 deletions(-)

diff --git a/backend/wayland/output.c b/backend/wayland/output.c
index 4fec1955..4a8fb0bf 100644
--- a/backend/wayland/output.c
+++ b/backend/wayland/output.c
@@ -21,9 +21,10 @@ static void surface_frame_callback(void *data, struct wl_callback *cb,
 		uint32_t time) {
 	struct wlr_wl_backend_output *output = data;
 	assert(output);
-	wlr_output_send_frame(&output->wlr_output);
 	wl_callback_destroy(cb);
 	output->frame_callback = NULL;
+
+	wlr_output_send_frame(&output->wlr_output);
 }
 
 static struct wl_callback_listener frame_listener = {
@@ -50,6 +51,11 @@ static bool wlr_wl_output_swap_buffers(struct wlr_output *wlr_output) {
 	struct wlr_wl_backend_output *output =
 		(struct wlr_wl_backend_output *)wlr_output;
 
+	if (output->frame_callback != NULL) {
+		wlr_log(L_ERROR, "Skipping buffer swap");
+		return false;
+	}
+
 	output->frame_callback = wl_surface_frame(output->surface);
 	wl_callback_add_listener(output->frame_callback, &frame_listener, output);
 
diff --git a/include/wlr/types/wlr_output.h b/include/wlr/types/wlr_output.h
index 5b6ba3e7..3eb1c6ff 100644
--- a/include/wlr/types/wlr_output.h
+++ b/include/wlr/types/wlr_output.h
@@ -77,6 +77,8 @@ struct wlr_output {
 		struct wl_signal destroy;
 	} events;
 
+	struct wl_event_source *idle_frame;
+
 	struct wlr_surface *fullscreen_surface;
 	struct wl_listener fullscreen_surface_commit;
 	struct wl_listener fullscreen_surface_destroy;
diff --git a/types/wlr_output.c b/types/wlr_output.c
index 8c9de541..54f4baf8 100644
--- a/types/wlr_output.c
+++ b/types/wlr_output.c
@@ -273,6 +273,8 @@ void wlr_output_init(struct wlr_output *output, struct wlr_backend *backend,
 
 	output->display_destroy.notify = handle_display_destroy;
 	wl_display_add_destroy_listener(display, &output->display_destroy);
+
+	output->frame_pending = true;
 }
 
 void wlr_output_destroy(struct wlr_output *output) {
@@ -466,6 +468,15 @@ surface_damage_finish:
 
 bool wlr_output_swap_buffers(struct wlr_output *output, struct timespec *when,
 		pixman_region32_t *damage) {
+	if (output->frame_pending) {
+		wlr_log(L_ERROR, "Tried to swap buffers when a frame is pending");
+		return false;
+	}
+	if (output->idle_frame != NULL) {
+		wl_event_source_remove(output->idle_frame);
+		output->idle_frame = NULL;
+	}
+
 	wl_signal_emit(&output->events.swap_buffers, damage);
 
 	int width, height;
@@ -522,18 +533,21 @@ void wlr_output_send_frame(struct wlr_output *output) {
 
 static void schedule_frame_handle_idle_timer(void *data) {
 	struct wlr_output *output = data;
-	wlr_output_send_frame(output);
+	output->idle_frame = NULL;
+	if (!output->frame_pending) {
+		wlr_output_send_frame(output);
+	}
 }
 
 void wlr_output_schedule_frame(struct wlr_output *output) {
-	if (output->frame_pending) {
+	if (output->frame_pending || output->idle_frame != NULL) {
 		return;
 	}
 
 	// TODO: ask the backend to send a frame event when appropriate instead
 	struct wl_event_loop *ev = wl_display_get_event_loop(output->display);
-	wl_event_loop_add_idle(ev, schedule_frame_handle_idle_timer, output);
-	output->frame_pending = true;
+	output->idle_frame =
+		wl_event_loop_add_idle(ev, schedule_frame_handle_idle_timer, output);
 }
 
 void wlr_output_set_gamma(struct wlr_output *output,
-- 
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