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 +1,80 @@
+/*
+ * 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_V1_H
+#define WLR_TYPES_WLR_LINUX_EXPLICIT_SYNCHRONIZATION_V1_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);
+
+/**
+ * Signal the provided timeline synchronization point when the last submitted
+ * buffer is ready to be acquired.
+ */
+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);
+
+/**
+ * Send a timeline synchronization point to the client which can be used to
+ * wait for the buffer to be released.
+ *
+ * The synchronization point must already be materialized: wait-before-submit
+ * is not supported.
+ */
+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

@@ -27,6 +27,7 @@ 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

@@ -46,6 +46,7 @@ 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',

types/wlr_linux_explicit_synchronization_v1.c

@@ -0,0 +1,364 @@
+#include <assert.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <wlr/render/timeline.h>
+#include <wlr/types/wlr_compositor.h>
+#include <wlr/types/wlr_linux_explicit_synchronization_v1.h>
+#include "linux-explicit-synchronization-unstable-v1-protocol.h"
+#include "util/signal.h"
+
+#define LINUX_EXPLICIT_SYNCHRONIZATION_V1_VERSION 2
+
+static const struct zwp_linux_explicit_synchronization_v1_interface
+	explicit_sync_impl;
+static const struct zwp_linux_surface_synchronization_v1_interface
+	surface_sync_impl;
+
+static struct wlr_linux_explicit_synchronization_v1 *
+explicit_sync_from_resource(struct wl_resource *resource) {
+	assert(wl_resource_instance_of(resource,
+		&zwp_linux_explicit_synchronization_v1_interface,
+		&explicit_sync_impl));
+	return wl_resource_get_user_data(resource);
+}
+
+// Returns NULL if the surface sync is inert
+static struct wlr_linux_surface_synchronization_v1 *
+surface_sync_from_resource(struct wl_resource *resource) {
+	assert(wl_resource_instance_of(resource,
+		&zwp_linux_surface_synchronization_v1_interface,
+		&surface_sync_impl));
+	return wl_resource_get_user_data(resource);
+}
+
+static struct wlr_linux_buffer_release_v1 *buffer_release_from_resource(
+		struct wl_resource *resource) {
+	assert(wl_resource_instance_of(resource,
+		&zwp_linux_buffer_release_v1_interface, NULL));
+	return wl_resource_get_user_data(resource);
+}
+
+static void buffer_release_destroy(
+		struct wlr_linux_buffer_release_v1 *buffer_release, int fence_fd) {
+	if (buffer_release == NULL) {
+		return;
+	}
+	if (fence_fd >= 0) {
+		zwp_linux_buffer_release_v1_send_fenced_release(
+			buffer_release->resource, fence_fd);
+	} else {
+		zwp_linux_buffer_release_v1_send_immediate_release(
+			buffer_release->resource);
+	}
+	wl_resource_destroy(buffer_release->resource);
+}
+
+static void buffer_release_handle_resource_destroy(struct wl_resource *resource) {
+	struct wlr_linux_buffer_release_v1 *buffer_release =
+		buffer_release_from_resource(resource);
+	free(buffer_release);
+}
+
+static void surface_sync_handle_destroy(struct wl_client *client,
+		struct wl_resource *resource) {
+	wl_resource_destroy(resource);
+}
+
+static void surface_sync_handle_set_acquire_fence(struct wl_client *client,
+		struct wl_resource *resource, int fence_fd) {
+	struct wlr_linux_surface_synchronization_v1 *surface_sync =
+		surface_sync_from_resource(resource);
+	if (surface_sync == NULL) {
+		close(fence_fd);
+		wl_resource_post_error(resource,
+			ZWP_LINUX_SURFACE_SYNCHRONIZATION_V1_ERROR_NO_SURFACE,
+			"the surface has been destroyed");
+		return;
+	}
+
+	if (surface_sync->pending.acquire_fence_fd >= 0) {
+		close(fence_fd);
+		wl_resource_post_error(resource,
+			ZWP_LINUX_SURFACE_SYNCHRONIZATION_V1_ERROR_DUPLICATE_FENCE,
+			"a fence FD was already set for this commit");
+		return;
+	}
+
+	// TODO: check that the FD is a sync_file
+
+	surface_sync->pending.acquire_fence_fd = fence_fd;
+}
+
+static void surface_sync_handle_get_release(struct wl_client *client,
+		struct wl_resource *resource, uint32_t id) {
+	struct wlr_linux_surface_synchronization_v1 *surface_sync =
+		surface_sync_from_resource(resource);
+	if (surface_sync == NULL) {
+		wl_resource_post_error(resource,
+			ZWP_LINUX_SURFACE_SYNCHRONIZATION_V1_ERROR_NO_SURFACE,
+			"the surface has been destroyed");
+		return;
+	}
+
+	if (surface_sync->pending.buffer_release != NULL) {
+		wl_resource_post_error(resource,
+			ZWP_LINUX_SURFACE_SYNCHRONIZATION_V1_ERROR_DUPLICATE_RELEASE,
+			"a buffer release has already been requested for this commit");
+		return;
+	}
+
+	struct wlr_linux_buffer_release_v1 *buffer_release =
+		calloc(1, sizeof(*buffer_release));
+	if (buffer_release == NULL) {
+		wl_resource_post_no_memory(resource);
+		return;
+	}
+
+	uint32_t version = wl_resource_get_version(resource);
+	buffer_release->resource = wl_resource_create(client,
+		&zwp_linux_buffer_release_v1_interface, version, id);
+	if (buffer_release->resource == NULL) {
+		wl_resource_post_no_memory(resource);
+		free(buffer_release);
+		return;
+	}
+	wl_resource_set_implementation(buffer_release->resource, NULL,
+		buffer_release, buffer_release_handle_resource_destroy);
+
+	surface_sync->pending.buffer_release = buffer_release;
+}
+
+static const struct zwp_linux_surface_synchronization_v1_interface
+		surface_sync_impl = {
+	.destroy = surface_sync_handle_destroy,
+	.set_acquire_fence = surface_sync_handle_set_acquire_fence,
+	.get_release = surface_sync_handle_get_release,
+};
+
+static void surface_sync_state_init(
+		struct wlr_linux_surface_synchronization_v1_state *state) {
+	memset(state, 0, sizeof(*state));
+	state->acquire_fence_fd = -1;
+}
+
+static void surface_sync_state_finish(
+		struct wlr_linux_surface_synchronization_v1_state *state) {
+	if (state->acquire_fence_fd >= 0) {
+		close(state->acquire_fence_fd);
+	}
+	buffer_release_destroy(state->buffer_release, -1);
+}
+
+static void surface_sync_destroy(
+		struct wlr_linux_surface_synchronization_v1 *surface_sync) {
+	if (surface_sync == NULL) {
+		return;
+	}
+	wl_list_remove(&surface_sync->surface_commit.link);
+	wlr_addon_finish(&surface_sync->addon);
+	wl_resource_set_user_data(surface_sync->resource, NULL);
+	surface_sync_state_finish(&surface_sync->pending);
+	surface_sync_state_finish(&surface_sync->current);
+	free(surface_sync);
+}
+
+static void surface_sync_handle_surface_commit(struct wl_listener *listener,
+		void *data) {
+	struct wlr_linux_surface_synchronization_v1 *surface_sync =
+		wl_container_of(listener, surface_sync, surface_commit);
+
+	if (surface_sync->pending.acquire_fence_fd >= 0 &&
+			surface_sync->surface->buffer == NULL) {
+		wl_resource_post_error(surface_sync->resource,
+			ZWP_LINUX_SURFACE_SYNCHRONIZATION_V1_ERROR_NO_BUFFER,
+			"acquire fence FD set but no buffer attached");
+		return;
+	}
+
+	if (surface_sync->pending.buffer_release != NULL &&
+			surface_sync->surface->buffer == NULL) {
+		wl_resource_post_error(surface_sync->resource,
+			ZWP_LINUX_SURFACE_SYNCHRONIZATION_V1_ERROR_NO_BUFFER,
+			"buffer release requested but no buffer attached");
+		return;
+	}
+
+	surface_sync_state_finish(&surface_sync->current);
+	surface_sync->current = surface_sync->pending;
+	surface_sync_state_init(&surface_sync->pending);
+}
+
+static void surface_sync_handle_resource_destroy(struct wl_resource *resource) {
+	struct wlr_linux_surface_synchronization_v1 *surface_sync =
+		surface_sync_from_resource(resource);
+	surface_sync_destroy(surface_sync);
+}
+
+static void surface_sync_handle_surface_destroy(struct wlr_addon *addon) {
+	struct wlr_linux_surface_synchronization_v1 *surface_sync =
+		wl_container_of(addon, surface_sync, addon);
+	surface_sync_destroy(surface_sync);
+}
+
+static const struct wlr_addon_interface addon_impl = {
+	.name = "zwp_linux_surface_synchronization_v1",
+	.destroy = surface_sync_handle_surface_destroy,
+};
+
+static void explicit_sync_handle_destroy(struct wl_client *client,
+		struct wl_resource *resource) {
+	wl_resource_destroy(resource);
+}
+
+static struct wlr_linux_surface_synchronization_v1 *surface_sync_from_surface(
+		struct wlr_linux_explicit_synchronization_v1 *explicit_sync,
+		struct wlr_surface *surface) {
+	struct wlr_addon *addon =
+		wlr_addon_find(&surface->addons, explicit_sync, &addon_impl);
+	if (addon == NULL) {
+		return NULL;
+	}
+	struct wlr_linux_surface_synchronization_v1 *surface_sync =
+		wl_container_of(addon, surface_sync, addon);
+	return surface_sync;
+}
+
+static void explicit_sync_handle_get_synchronization(struct wl_client *client,
+		struct wl_resource *resource, uint32_t id,
+		struct wl_resource *surface_resource) {
+	struct wlr_linux_explicit_synchronization_v1 *explicit_sync =
+		explicit_sync_from_resource(resource);
+	struct wlr_surface *surface = wlr_surface_from_resource(surface_resource);
+
+	if (surface_sync_from_surface(explicit_sync, surface) != NULL) {
+		wl_resource_post_error(resource,
+			ZWP_LINUX_EXPLICIT_SYNCHRONIZATION_V1_ERROR_SYNCHRONIZATION_EXISTS,
+			"zwp_linux_surface_synchronization_v1 already created for this surface");
+		return;
+	}
+
+	struct wlr_linux_surface_synchronization_v1 *surface_sync =
+		calloc(1, sizeof(*surface_sync));
+	if (surface_sync == NULL) {
+		wl_resource_post_no_memory(resource);
+		return;
+	}
+
+	uint32_t version = wl_resource_get_version(resource);
+	surface_sync->resource = wl_resource_create(client,
+		&zwp_linux_surface_synchronization_v1_interface, version, id);
+	if (surface_sync->resource == NULL) {
+		wl_resource_post_no_memory(resource);
+		free(surface_sync);
+		return;
+	}
+	wl_resource_set_implementation(surface_sync->resource,
+		&surface_sync_impl, surface_sync, surface_sync_handle_resource_destroy);
+
+	surface_sync->surface = surface;
+	surface_sync_state_init(&surface_sync->pending);
+	surface_sync_state_init(&surface_sync->current);
+
+	surface_sync->surface_commit.notify = surface_sync_handle_surface_commit;
+	wl_signal_add(&surface->events.commit, &surface_sync->surface_commit);
+
+	wlr_addon_init(&surface_sync->addon, &surface->addons, explicit_sync,
+		&addon_impl);
+}
+
+static const struct zwp_linux_explicit_synchronization_v1_interface
+		explicit_sync_impl = {
+	.destroy = explicit_sync_handle_destroy,
+	.get_synchronization = explicit_sync_handle_get_synchronization,
+};
+
+static void explicit_sync_bind(struct wl_client *client, void *data,
+		uint32_t version, uint32_t id) {
+	struct wlr_linux_explicit_synchronization_v1 *explicit_sync = data;
+
+	struct wl_resource *resource = wl_resource_create(client,
+		&zwp_linux_explicit_synchronization_v1_interface, version, id);
+	if (resource == NULL) {
+		wl_client_post_no_memory(client);
+		return;
+	}
+	wl_resource_set_implementation(resource, &explicit_sync_impl,
+		explicit_sync, NULL);
+}
+
+static void handle_display_destroy(struct wl_listener *listener, void *data) {
+	struct wlr_linux_explicit_synchronization_v1 *explicit_sync =
+		wl_container_of(listener, explicit_sync, display_destroy);
+	wlr_signal_emit_safe(&explicit_sync->events.destroy, NULL);
+	wl_list_remove(&explicit_sync->display_destroy.link);
+	wl_global_destroy(explicit_sync->global);
+	free(explicit_sync);
+}
+
+struct wlr_linux_explicit_synchronization_v1 *
+wlr_linux_explicit_synchronization_v1_create(struct wl_display *display) {
+	struct wlr_linux_explicit_synchronization_v1 *explicit_sync =
+		calloc(1, sizeof(*explicit_sync));
+	if (explicit_sync == NULL) {
+		return NULL;
+	}
+
+	wl_signal_init(&explicit_sync->events.destroy);
+
+	explicit_sync->global = wl_global_create(display,
+		&zwp_linux_explicit_synchronization_v1_interface,
+		LINUX_EXPLICIT_SYNCHRONIZATION_V1_VERSION, explicit_sync,
+		explicit_sync_bind);
+	if (explicit_sync->global == NULL) {
+		free(explicit_sync);
+		return NULL;
+	}
+
+	explicit_sync->display_destroy.notify = handle_display_destroy;
+	wl_display_add_destroy_listener(display, &explicit_sync->display_destroy);
+
+	return explicit_sync;
+}
+
+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) {
+	struct wlr_linux_surface_synchronization_v1 *surface_sync =
+		surface_sync_from_surface(explicit_sync, surface);
+	if (!surface_sync) {
+		// TODO: fallback to DMA-BUF fence export
+		return false;
+	}
+
+	return wlr_render_timeline_import_sync_file(timeline, dst_point,
+		surface_sync->current.acquire_fence_fd);
+}
+
+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) {
+	struct wlr_linux_surface_synchronization_v1 *surface_sync =
+		surface_sync_from_surface(explicit_sync, surface);
+	if (!surface_sync) {
+		return true;
+	}
+
+	struct wlr_linux_buffer_release_v1 *buffer_release =
+		surface_sync->current.buffer_release;
+	surface_sync->current.buffer_release = NULL;
+	if (!buffer_release) {
+		return true;
+	}
+
+	int fence_fd = wlr_render_timeline_export_sync_file(timeline, src_point);
+	if (fence_fd < 0) {
+		return false;
+	}
+
+	buffer_release_destroy(buffer_release, fence_fd);
+	close(fence_fd);
+	return true;
+}