x11: use xdg-screensaver suspend/resume

If it doesn't work this time, I'll remove all X11 screensaver code.

Fixes #4763.

video/out/x11_common.c

@@ -37,6 +37,8 @@
 #include <X11/extensions/Xinerama.h>
 #include <X11/extensions/Xrandr.h>
 
+#include "osdep/atomic.h"
+
 #include "config.h"
 #include "misc/bstr.h"
 #include "options/options.h"
@@ -135,7 +137,6 @@ static atomic_int x11_error_silence;
 
 static void vo_x11_update_geometry(struct vo *vo);
 static void vo_x11_fullscreen(struct vo *vo);
-static void xscreensaver_heartbeat(struct vo_x11_state *x11);
 static void set_screensaver(struct vo_x11_state *x11, bool enabled);
 static void vo_x11_selectinput_witherr(struct vo *vo, Display *display,
                                        Window w, long event_mask);
@@ -503,27 +504,63 @@ static void vo_x11_get_bounding_monitors(struct vo_x11_state *x11, long b[4])
 static void *screensaver_thread(void *arg)
 {
     struct vo_x11_state *x11 = arg;
+    bool suspend = false;
+    bool run = true;
 
-    for (;;) {
-        sem_wait(&x11->screensaver_sem);
-        // don't queue multiple wakeups
-        while (!sem_trywait(&x11->screensaver_sem)) {}
+    while (run) {
+        pthread_mutex_lock(&x11->screensaver_thread_lock);
+        bool suspend_new = suspend;
+        for (;;) {
+            run = x11->screensaver_thread_running;
+            suspend_new = x11->screensaver_thread_suspend;
+            if (!run || suspend != suspend_new)
+                break;
+            pthread_cond_wait(&x11->screensaver_thread_wakeup,
+                              &x11->screensaver_thread_lock);
+        }
+        pthread_mutex_unlock(&x11->screensaver_thread_lock);
 
-        if (atomic_load(&x11->screensaver_terminate))
-            break;
+        if (!run) {
+            suspend_new = false; // make sure to resume on exit
+            if (suspend == suspend_new)
+                break;
+        }
 
-        char *args[] = {"xdg-screensaver", "reset", NULL};
-        int status = mp_subprocess(args, NULL, NULL, mp_devnull, mp_devnull, &(char*){0});
+        char *args[] = {"xdg-screensaver", suspend_new ? "suspend" : "resume",
+                        mp_tprintf(32, "%lx", x11->screensaver_thread_window),
+                        NULL};
+        int status = mp_subprocess(args, NULL, NULL, mp_devnull, mp_devnull,
+                                   &(char*){0});
         if (status) {
-            MP_VERBOSE(x11, "Disabling screensaver failed (%d). Make sure the "
+            MP_VERBOSE(x11, "Updating screensaver failed (%d). Make sure the "
                             "xdg-screensaver script is installed.\n", status);
             break;
         }
+
+        suspend = suspend_new;
     }
 
     return NULL;
 }
 
+static void screensaver_thread_update(struct vo_x11_state *x11)
+{
+    if (!x11->screensaver_thread_running && x11->window) {
+        x11->screensaver_thread_window = x11->window;
+        x11->screensaver_thread_running = true;
+        if (pthread_create(&x11->screensaver_thread, NULL, screensaver_thread, x11))
+            x11->screensaver_thread_running = false;
+    }
+
+    if (!x11->screensaver_thread_running)
+        return;
+
+    pthread_mutex_lock(&x11->screensaver_thread_lock);
+    x11->screensaver_thread_suspend = !x11->screensaver_enabled;
+    pthread_cond_signal(&x11->screensaver_thread_wakeup);
+    pthread_mutex_unlock(&x11->screensaver_thread_lock);
+}
+
 int vo_x11_init(struct vo *vo)
 {
     struct mp_vo_opts *opts = vo->opts;
@@ -544,12 +581,8 @@ int vo_x11_init(struct vo *vo)
     };
     vo->x11 = x11;
 
-    sem_init(&x11->screensaver_sem, 0, 0);
-    if (pthread_create(&x11->screensaver_thread, NULL, screensaver_thread, x11)) {
-        sem_destroy(&x11->screensaver_sem);
-        goto error;
-    }
-    x11->screensaver_thread_running = true;
+    pthread_mutex_init(&x11->screensaver_thread_lock, NULL);
+    pthread_cond_init(&x11->screensaver_thread_wakeup, NULL);
 
     x11_error_output = x11->log;
     XSetErrorHandler(x11_errorhandler);
@@ -773,12 +806,16 @@ void vo_x11_uninit(struct vo *vo)
     }
 
     if (x11->screensaver_thread_running) {
-        atomic_store(&x11->screensaver_terminate, true);
-        sem_post(&x11->screensaver_sem);
+        pthread_mutex_lock(&x11->screensaver_thread_lock);
+        x11->screensaver_thread_running = false;
+        pthread_cond_signal(&x11->screensaver_thread_wakeup);
+        pthread_mutex_unlock(&x11->screensaver_thread_lock);
         pthread_join(x11->screensaver_thread, NULL);
-        sem_destroy(&x11->screensaver_sem);
     }
 
+    pthread_mutex_destroy(&x11->screensaver_thread_lock);
+    pthread_cond_destroy(&x11->screensaver_thread_wakeup);
+
     if (x11->wakeup_pipe[0] >= 0) {
         close(x11->wakeup_pipe[0]);
         close(x11->wakeup_pipe[1]);
@@ -1041,8 +1078,6 @@ void vo_x11_check_events(struct vo *vo)
     Display *display = vo->x11->display;
     XEvent Event;
 
-    xscreensaver_heartbeat(vo->x11);
-
     while (XPending(display)) {
         XNextEvent(display, &Event);
         MP_TRACE(x11, "XEvent: %d\n", Event.type);
@@ -1424,6 +1459,8 @@ static void vo_x11_create_window(struct vo *vo, XVisualInfo *vis,
         vo_x11_set_property_utf8(vo, XA(x11, _GTK_THEME_VARIANT), "dark");
     }
     vo_x11_xembed_update(x11, 0);
+
+    screensaver_thread_update(x11);
 }
 
 static void vo_x11_map_window(struct vo *vo, struct mp_rect rc)
@@ -1898,18 +1935,6 @@ void vo_x11_wait_events(struct vo *vo, int64_t until_time_us)
         mp_flush_wakeup_pipe(x11->wakeup_pipe[0]);
 }
 
-static void xscreensaver_heartbeat(struct vo_x11_state *x11)
-{
-    double time = mp_time_sec();
-
-    if (x11->display && !x11->screensaver_enabled &&
-        (time - x11->screensaver_time_last) >= 10)
-    {
-        x11->screensaver_time_last = time;
-        sem_post(&x11->screensaver_sem);
-    }
-}
-
 static void set_screensaver(struct vo_x11_state *x11, bool enabled)
 {
     Display *mDisplay = x11->display;
@@ -1917,6 +1942,7 @@ static void set_screensaver(struct vo_x11_state *x11, bool enabled)
         return;
     MP_VERBOSE(x11, "%s screensaver.\n", enabled ? "Enabling" : "Disabling");
     x11->screensaver_enabled = enabled;
+    screensaver_thread_update(x11);
     int nothing;
     if (DPMSQueryExtension(mDisplay, &nothing, &nothing)) {
         BOOL onoff = 0;

video/out/x11_common.h

@@ -24,9 +24,6 @@
 #include <X11/Xlib.h>
 #include <X11/Xutil.h>
 
-#include "osdep/atomic.h"
-#include "osdep/semaphore.h"
-
 #include "common/common.h"
 
 struct vo;
@@ -66,11 +63,13 @@ struct vo_x11_state {
 
     bool screensaver_enabled;
     bool dpms_touched;
-    double screensaver_time_last;
+
+    long screensaver_thread_window;
     pthread_t screensaver_thread;
+    pthread_mutex_t screensaver_thread_lock;
+    pthread_cond_t screensaver_thread_wakeup;
     bool screensaver_thread_running;
-    sem_t screensaver_sem;
-    atomic_bool screensaver_terminate;
+    bool screensaver_thread_suspend;
 
     XIM xim;
     XIC xic;