From 63792b38e46ae1741a6492d3c0183cb9566e4c9f Mon Sep 17 00:00:00 2001
From: Simon Ser <contact@emersion.fr>
Date: Fri, 11 Aug 2023 19:28:07 +0200
Subject: [PATCH] backend/session: take wl_event_loop instead of wl_display

wl_display holds a lot more than wlr_session needs: wlr_session
only needs to wait for a FD to become readable, but wl_display
provides full access to the Wayland client and protocol objects.

Switch to wl_event_loop to better reflect the above.
---
 backend/backend.c             |  7 +++----
 backend/drm/monitor.c         |  8 ++++----
 backend/session/session.c     | 28 ++++++++++++----------------
 include/backend/drm/monitor.h |  3 ++-
 include/wlr/backend/session.h |  6 +++---
 5 files changed, 24 insertions(+), 28 deletions(-)

diff --git a/backend/backend.c b/backend/backend.c
index e5b8db14..1e57e832 100644
--- a/backend/backend.c
+++ b/backend/backend.c
@@ -73,7 +73,8 @@ void wlr_backend_destroy(struct wlr_backend *backend) {
 
 static struct wlr_session *session_create_and_wait(struct wl_display *disp) {
 #if WLR_HAS_SESSION
-	struct wlr_session *session = wlr_session_create(disp);
+	struct wl_event_loop *event_loop = wl_display_get_event_loop(disp);
+	struct wlr_session *session = wlr_session_create(event_loop);
 
 	if (!session) {
 		wlr_log(WLR_ERROR, "Failed to start a session");
@@ -85,8 +86,6 @@ static struct wlr_session *session_create_and_wait(struct wl_display *disp) {
 
 		int64_t started_at = get_current_time_msec();
 		int64_t timeout = WAIT_SESSION_TIMEOUT;
-		struct wl_event_loop *event_loop =
-			wl_display_get_event_loop(session->display);
 
 		while (!session->active) {
 			int ret = wl_event_loop_dispatch(event_loop, (int)timeout);
@@ -234,7 +233,7 @@ static bool attempt_drm_backend(struct wl_display *display,
 	}
 
 	if (getenv("WLR_DRM_DEVICES") == NULL) {
-		drm_backend_monitor_create(backend, primary_drm, session);
+		drm_backend_monitor_create(backend, primary_drm, session, display);
 	}
 
 	return true;
diff --git a/backend/drm/monitor.c b/backend/drm/monitor.c
index 4b1eeaa9..939a00ff 100644
--- a/backend/drm/monitor.c
+++ b/backend/drm/monitor.c
@@ -26,7 +26,7 @@ static void handle_add_drm_card(struct wl_listener *listener, void *data) {
 
 	wlr_log(WLR_DEBUG, "Creating DRM backend for %s after hotplug", event->path);
 	struct wlr_backend *child_drm = wlr_drm_backend_create(
-		backend_monitor->session->display, backend_monitor->session,
+		backend_monitor->display, backend_monitor->session,
 		dev, backend_monitor->primary_drm);
 	if (!child_drm) {
 		wlr_log(WLR_ERROR, "Failed to create DRM backend after hotplug");
@@ -64,9 +64,8 @@ static void handle_multi_destroy(struct wl_listener *listener, void *data) {
 }
 
 struct wlr_drm_backend_monitor *drm_backend_monitor_create(
-		struct wlr_backend *multi,
-		struct wlr_backend *primary_drm,
-		struct wlr_session *session) {
+		struct wlr_backend *multi, struct wlr_backend *primary_drm,
+		struct wlr_session *session, struct wl_display *display) {
 	struct wlr_drm_backend_monitor *monitor = calloc(1, sizeof(*monitor));
 	if (!monitor) {
 		wlr_log_errno(WLR_ERROR, "Allocation failed");
@@ -76,6 +75,7 @@ struct wlr_drm_backend_monitor *drm_backend_monitor_create(
 	monitor->multi = multi;
 	monitor->primary_drm = primary_drm;
 	monitor->session = session;
+	monitor->display = display;
 
 	monitor->session_add_drm_card.notify = handle_add_drm_card;
 	wl_signal_add(&session->events.add_drm_card, &monitor->session_add_drm_card);
diff --git a/backend/session/session.c b/backend/session/session.c
index 7b8b0bc2..52b2654b 100644
--- a/backend/session/session.c
+++ b/backend/session/session.c
@@ -39,7 +39,7 @@ static int libseat_event(int fd, uint32_t mask, void *data) {
 	struct wlr_session *session = data;
 	if (libseat_dispatch(session->seat_handle, 0) == -1) {
 		wlr_log_errno(WLR_ERROR, "Failed to dispatch libseat");
-		wl_display_terminate(session->display);
+		wlr_session_destroy(session);
 	}
 	return 1;
 }
@@ -71,7 +71,8 @@ static void log_libseat(enum libseat_log_level level,
 	_wlr_vlog(importance, wlr_fmt, args);
 }
 
-static int libseat_session_init(struct wlr_session *session, struct wl_display *disp) {
+static int libseat_session_init(struct wlr_session *session,
+		struct wl_event_loop *event_loop) {
 	libseat_set_log_handler(log_libseat);
 	libseat_set_log_level(LIBSEAT_LOG_LEVEL_INFO);
 
@@ -91,7 +92,6 @@ static int libseat_session_init(struct wlr_session *session, struct wl_display *
 	}
 	snprintf(session->seat, sizeof(session->seat), "%s", seat_name);
 
-	struct wl_event_loop *event_loop = wl_display_get_event_loop(disp);
 	session->libseat_event = wl_event_loop_add_fd(event_loop, libseat_get_fd(session->seat_handle),
 		WL_EVENT_READABLE, libseat_event, session);
 	if (session->libseat_event == NULL) {
@@ -226,25 +226,26 @@ out:
 	return 1;
 }
 
-static void handle_display_destroy(struct wl_listener *listener, void *data) {
+static void handle_event_loop_destroy(struct wl_listener *listener, void *data) {
 	struct wlr_session *session =
-		wl_container_of(listener, session, display_destroy);
+		wl_container_of(listener, session, event_loop_destroy);
 	wlr_session_destroy(session);
 }
 
-struct wlr_session *wlr_session_create(struct wl_display *disp) {
+struct wlr_session *wlr_session_create(struct wl_event_loop *event_loop) {
 	struct wlr_session *session = calloc(1, sizeof(*session));
 	if (!session) {
 		wlr_log_errno(WLR_ERROR, "Allocation failed");
 		return NULL;
 	}
 
+	session->event_loop = event_loop;
 	wl_signal_init(&session->events.active);
 	wl_signal_init(&session->events.add_drm_card);
 	wl_signal_init(&session->events.destroy);
 	wl_list_init(&session->devices);
 
-	if (libseat_session_init(session, disp) == -1) {
+	if (libseat_session_init(session, event_loop) == -1) {
 		wlr_log(WLR_ERROR, "Failed to load session backend");
 		goto error_open;
 	}
@@ -264,7 +265,6 @@ struct wlr_session *wlr_session_create(struct wl_display *disp) {
 	udev_monitor_filter_add_match_subsystem_devtype(session->mon, "drm", NULL);
 	udev_monitor_enable_receiving(session->mon);
 
-	struct wl_event_loop *event_loop = wl_display_get_event_loop(disp);
 	int fd = udev_monitor_get_fd(session->mon);
 
 	session->udev_event = wl_event_loop_add_fd(event_loop, fd,
@@ -274,10 +274,8 @@ struct wlr_session *wlr_session_create(struct wl_display *disp) {
 		goto error_mon;
 	}
 
-	session->display = disp;
-
-	session->display_destroy.notify = handle_display_destroy;
-	wl_display_add_destroy_listener(disp, &session->display_destroy);
+	session->event_loop_destroy.notify = handle_event_loop_destroy;
+	wl_event_loop_add_destroy_listener(event_loop, &session->event_loop_destroy);
 
 	return session;
 
@@ -298,7 +296,7 @@ void wlr_session_destroy(struct wlr_session *session) {
 	}
 
 	wl_signal_emit_mutable(&session->events.destroy, session);
-	wl_list_remove(&session->display_destroy.link);
+	wl_list_remove(&session->event_loop_destroy.link);
 
 	wl_event_source_remove(session->udev_event);
 	udev_monitor_unref(session->mon);
@@ -472,10 +470,8 @@ ssize_t wlr_session_find_gpus(struct wlr_session *session,
 
 		int64_t started_at = get_current_time_msec();
 		int64_t timeout = WAIT_GPU_TIMEOUT;
-		struct wl_event_loop *event_loop =
-			wl_display_get_event_loop(session->display);
 		while (!handler.added) {
-			int ret = wl_event_loop_dispatch(event_loop, (int)timeout);
+			int ret = wl_event_loop_dispatch(session->event_loop, (int)timeout);
 			if (ret < 0) {
 				wlr_log_errno(WLR_ERROR, "Failed to wait for DRM card device: "
 					"wl_event_loop_dispatch failed");
diff --git a/include/backend/drm/monitor.h b/include/backend/drm/monitor.h
index 51817193..bf5bda2d 100644
--- a/include/backend/drm/monitor.h
+++ b/include/backend/drm/monitor.h
@@ -10,6 +10,7 @@ struct wlr_drm_backend_monitor {
 	struct wlr_backend *multi;
 	struct wlr_backend *primary_drm;
 	struct wlr_session *session;
+	struct wl_display *display;
 
 	struct wl_listener multi_destroy;
 	struct wl_listener primary_drm_destroy;
@@ -19,6 +20,6 @@ struct wlr_drm_backend_monitor {
 
 struct wlr_drm_backend_monitor *drm_backend_monitor_create(
 	struct wlr_backend *multi, struct wlr_backend *primary_drm,
-	struct wlr_session *session);
+	struct wlr_session *session, struct wl_display *display);
 
 #endif
diff --git a/include/wlr/backend/session.h b/include/wlr/backend/session.h
index 3583b317..b61de852 100644
--- a/include/wlr/backend/session.h
+++ b/include/wlr/backend/session.h
@@ -42,8 +42,8 @@ struct wlr_session {
 
 	struct wl_list devices;
 
-	struct wl_display *display;
-	struct wl_listener display_destroy;
+	struct wl_event_loop *event_loop;
+	struct wl_listener event_loop_destroy;
 
 	struct {
 		struct wl_signal active;
@@ -80,7 +80,7 @@ struct wlr_device_change_event {
  *
  * Returns NULL on error.
  */
-struct wlr_session *wlr_session_create(struct wl_display *disp);
+struct wlr_session *wlr_session_create(struct wl_event_loop *loop);
 
 /*
  * Closes a previously opened session and restores the virtual terminal.