linux-explicit-synchronization-v1: new protocol implementation

This patch adds support for the
linux-explicit-synchronization-unstable-v1 protocol.

To test, run weston-simple-dmabuf-egl.

include/wlr/types/wlr_linux_explicit_synchronization_v1.h

@@ -0,0 +1,69 @@
+/*
+ * 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_LINUX_EXPLICIT_SYNCHRONIZATION_H
+#define WLR_TYPES_WLR_LINUX_EXPLICIT_SYNCHRONIZATION_H
+
+#include <wayland-server-core.h>
+#include <wlr/util/addon.h>
+
+struct wlr_linux_surface_synchronization_v1_state {
+	int acquire_fence_fd;
+	struct wlr_linux_buffer_release_v1 *buffer_release;
+};
+
+struct wlr_linux_surface_synchronization_v1 {
+	struct wl_resource *resource;
+	struct wlr_surface *surface;
+
+	// private state
+
+	struct wlr_addon addon;
+
+	struct wlr_linux_surface_synchronization_v1_state pending, current;
+
+	struct wl_listener surface_commit;
+};
+
+struct wlr_linux_buffer_release_v1 {
+	struct wl_resource *resource;
+};
+
+struct wlr_linux_explicit_synchronization_v1 {
+	struct wl_global *global;
+
+	struct {
+		struct wl_signal destroy;
+	} events;
+
+	// private state
+
+	struct wl_listener display_destroy;
+};
+
+/**
+ * Advertise explicit synchronization support to clients.
+ *
+ * The compositor must be prepared to handle fences coming from clients and to
+ * send release fences correctly. In particular, both the renderer and the
+ * backend need to support explicit synchronization.
+ */
+struct wlr_linux_explicit_synchronization_v1 *
+wlr_linux_explicit_synchronization_v1_create(struct wl_display *display);
+
+bool wlr_linux_explicit_synchronization_v1_signal_surface_timeline(
+	struct wlr_linux_explicit_synchronization_v1 *explicit_sync,
+	struct wlr_surface *surface, struct wlr_render_timeline *timeline,
+	uint64_t dst_point);
+
+bool wlr_linux_explicit_synchronization_v1_wait_surface_timeline(
+	struct wlr_linux_explicit_synchronization_v1 *explicit_sync,
+	struct wlr_surface *surface, struct wlr_render_timeline *timeline,
+	uint64_t src_point);
+
+#endif

protocol/meson.build

@@ -26,6 +26,7 @@ protocols = {
 	'idle-inhibit-unstable-v1': wl_protocol_dir / 'unstable/idle-inhibit/idle-inhibit-unstable-v1.xml',
 	'keyboard-shortcuts-inhibit-unstable-v1': wl_protocol_dir / 'unstable/keyboard-shortcuts-inhibit/keyboard-shortcuts-inhibit-unstable-v1.xml',
 	'linux-dmabuf-unstable-v1': wl_protocol_dir / 'unstable/linux-dmabuf/linux-dmabuf-unstable-v1.xml',
+	'linux-explicit-synchronization-unstable-v1': wl_protocol_dir / 'unstable/linux-explicit-synchronization/linux-explicit-synchronization-unstable-v1.xml',
 	'pointer-constraints-unstable-v1': wl_protocol_dir / 'unstable/pointer-constraints/pointer-constraints-unstable-v1.xml',
 	'pointer-gestures-unstable-v1': wl_protocol_dir / 'unstable/pointer-gestures/pointer-gestures-unstable-v1.xml',
 	'primary-selection-unstable-v1': wl_protocol_dir / 'unstable/primary-selection/primary-selection-unstable-v1.xml',

types/meson.build

@@ -38,6 +38,7 @@ wlr_files += files(
 	'wlr_keyboard_shortcuts_inhibit_v1.c',
 	'wlr_layer_shell_v1.c',
 	'wlr_linux_dmabuf_v1.c',
+	'wlr_linux_explicit_synchronization_v1.c',
 	'wlr_matrix.c',
 	'wlr_output_damage.c',
 	'wlr_output_layout.c',