Merge branch 'scheduling-2-better-this-time' into 'master'

Add new frame scheduler interface

See merge request wlroots/wlroots!4307

include/backend/headless.h

@@ -4,8 +4,6 @@
 #include <wlr/backend/headless.h>
 #include <wlr/backend/interface.h>
 
-#define HEADLESS_DEFAULT_REFRESH (60 * 1000) // 60 Hz
-
 struct wlr_headless_backend {
 	struct wlr_backend backend;
 	struct wl_event_loop *event_loop;
@@ -19,9 +17,6 @@ struct wlr_headless_output {
 
 	struct wlr_headless_backend *backend;
 	struct wl_list link;
-
-	struct wl_event_source *frame_timer;
-	int frame_delay; // ms
 };
 
 struct wlr_headless_backend *headless_backend_from_backend(

include/wlr/backend/wayland.h

@@ -48,6 +48,11 @@ struct wlr_output *wlr_wl_output_create_from_surface(struct wlr_backend *backend
  */
 bool wlr_backend_is_wl(struct wlr_backend *backend);
 
+/**
+ * Check whether the Wayland server advertises the wp_presentation protocol.
+ */
+bool wlr_wl_backend_has_presentation_time(struct wlr_backend *backend);
+
 /**
  * Check whether the provided input device is a Wayland input device.
  */

include/wlr/interfaces/wlr_frame_scheduler.h

@@ -0,0 +1,26 @@
+/*
+ * This an unstable interface of wlroots. No guarantees are made regarding the
+ * future consistency of this API.
+ */
+#ifndef WLR_USE_UNSTABLE
+#error "Add -DWLR_USE_UNSTABLE to enable unstable wlroots features"
+#endif
+
+#ifndef WLR_INTERFACES_WLR_FRAME_SCHEDULER_H
+#define WLR_INTERFACES_WLR_FRAME_SCHEDULER_H
+
+struct wlr_frame_scheduler;
+struct wlr_output;
+
+struct wlr_frame_scheduler_impl {
+	/**
+	 * Ensure that the scheduler->frame signal will be fired in the future.
+	 */
+	void (*schedule_frame)(struct wlr_frame_scheduler *scheduler);
+	void (*destroy)(struct wlr_frame_scheduler *scheduler);
+};
+
+void wlr_frame_scheduler_init(struct wlr_frame_scheduler *scheduler,
+	const struct wlr_frame_scheduler_impl *impl, struct wlr_output *output);
+
+#endif

include/wlr/interfaces/wlr_output.h

@@ -108,12 +108,6 @@ void wlr_output_init(struct wlr_output *output, struct wlr_backend *backend,
  * output changes.
  */
 void wlr_output_update_needs_frame(struct wlr_output *output);
-/**
- * Send a frame event.
- *
- * See wlr_output.events.frame.
- */
-void wlr_output_send_frame(struct wlr_output *output);
 /**
  * Send a present event.
  *

include/wlr/types/wlr_frame_scheduler.h

@@ -0,0 +1,68 @@
+/*
+ * This an unstable interface of wlroots. No guarantees are made regarding the
+ * future consistency of this API.
+ */
+#ifndef WLR_USE_UNSTABLE
+#error "Add -DWLR_USE_UNSTABLE to enable unstable wlroots features"
+#endif
+
+#ifndef WLR_TYPES_WLR_FRAME_SCHEDULER_H
+#define WLR_TYPES_WLR_FRAME_SCHEDULER_H
+
+#include <stdbool.h>
+#include <wayland-server-core.h>
+
+struct wlr_frame_scheduler_impl;
+
+struct wlr_frame_scheduler {
+	struct wlr_output *output;
+
+	struct {
+		struct wl_signal frame;
+	} events;
+
+	// Whether the render loop should be kept awake. True iff wlr_frame_scheduler_schedule_frame() was
+	// called since the last frame event.
+	bool needs_frame;
+
+	// private state
+
+	const struct wlr_frame_scheduler_impl *impl;
+
+	struct wl_listener backend_needs_frame;
+};
+
+/**
+ * The present scheduler maintains a render loop based on `wlr_output.events.present`. To wake the
+ * render loop, it emits the frame signal when the compositor's event loop is idle.
+ */
+struct wlr_frame_scheduler *wlr_present_scheduler_create(struct wlr_output *output);
+/**
+ * The Wayland scheduler maintains a render loop based on wl_surface.frame callbacks. To wake the
+ * render loop, it emits the frame signal when the compositor's event loop is idle.
+ */
+struct wlr_frame_scheduler *wlr_wl_scheduler_create(struct wlr_output *output);
+/**
+ * The interval scheduler maintains a render loop based on a timer. To wake the render loop, it
+ * emits the frame signal when the compositor's event loop is idle.
+ */
+struct wlr_frame_scheduler *wlr_interval_scheduler_create(struct wlr_output *output);
+
+/**
+ * Creates an appropriate frame scheduler for the given output's backend capabilities.
+ */
+struct wlr_frame_scheduler *wlr_frame_scheduler_autocreate(struct wlr_output *output);
+/**
+ * Inform the scheduler that a frame signal is needed. The scheduler implementation will choose a
+ * good time to emit the signal. The signal is emitted only if this function has been called at
+ * least once since the last signal.
+ */
+void wlr_frame_scheduler_schedule_frame(struct wlr_frame_scheduler *scheduler);
+/**
+ * Emits a frame signal iff `wlr_frame_scheduler_schedule_frame()` has been called since the last
+ * frame signal.
+ */
+void wlr_frame_scheduler_emit_frame(struct wlr_frame_scheduler *scheduler);
+void wlr_frame_scheduler_destroy(struct wlr_frame_scheduler *scheduler);
+
+#endif

include/wlr/types/wlr_output.h

@@ -150,10 +150,6 @@ struct wlr_output {
 	enum wlr_output_adaptive_sync_status adaptive_sync_status;
 	uint32_t render_format;
 
-	bool needs_frame;
-	// damage for cursors and fullscreen surface, in output-local coordinates
-	bool frame_pending;
-
 	// true for example with VR headsets
 	bool non_desktop;
 
@@ -161,8 +157,6 @@ struct wlr_output {
 	uint32_t commit_seq;
 
 	struct {
-		// Request to render a frame
-		struct wl_signal frame;
 		// Emitted when software cursors or backend-specific logic damage the
 		// output
 		struct wl_signal damage; // struct wlr_output_event_damage
@@ -183,7 +177,6 @@ struct wlr_output {
 		struct wl_signal destroy;
 	} events;
 
-	struct wl_event_source *idle_frame;
 	struct wl_event_source *idle_done;
 
 	int attach_render_locks; // number of locks forcing rendering
@@ -334,11 +327,6 @@ bool wlr_output_test_state(struct wlr_output *output,
  */
 bool wlr_output_commit_state(struct wlr_output *output,
 	const struct wlr_output_state *state);
-/**
- * Manually schedules a `frame` event. If a `frame` event is already pending,
- * it is a no-op.
- */
-void wlr_output_schedule_frame(struct wlr_output *output);
 /**
  * Returns the maximum length of each gamma ramp, or 0 if unsupported.
  */

include/wlr/types/wlr_scene.h

@@ -199,6 +199,7 @@ struct wlr_scene_output {
 	struct wlr_output *output;
 	struct wl_list link; // wlr_scene.outputs
 	struct wlr_scene *scene;
+	struct wlr_frame_scheduler *frame_scheduler;
 	struct wlr_addon addon;
 
 	struct wlr_damage_ring damage_ring;
@@ -218,7 +219,6 @@ struct wlr_scene_output {
 
 	struct wl_listener output_commit;
 	struct wl_listener output_damage;
-	struct wl_listener output_needs_frame;
 
 	struct wl_list damage_highlight_regions;