player: remove the last instances of polling

Mouse cursor handling, --heartbeat-cmd, and OSD messages basically
relied on polling. For this reason, the playloop always used a small
timeout (not more than 500ms).

Fix these cases, and raise the timeout to 100 seconds. There is no
reason behind this number; for this specific purpose it's as close to
infinity as any other number.

On MS Windows, or if vo_sdl is used, the timeout remains very small.
In these cases the GUI code doesn't do proper event handling in the
first place, and fixing it requires much more effort.

getch2_poll() still does polling, because as far as I'm aware no event-
based way to detect this state change exists.

player/core.h

@@ -291,9 +291,11 @@ typedef struct MPContext {
 
     double audio_delay;
 
-    double last_heartbeat;
+    double next_heartbeat;
     double last_idle_tick;
 
+    double sleeptime;      // number of seconds to sleep before next iteration
+
     double mouse_timer;
     unsigned int mouse_event_ts;
     bool mouse_cursor_visible;

player/osd.c

@@ -314,19 +314,21 @@ static mp_osd_msg_t *get_osd_msg(struct MPContext *mpctx)
     mp_osd_msg_t *msg = mpctx->osd_msg_stack;
     if (msg) {
         if (!msg->started || msg->time > diff) {
+            // display it
             if (msg->started)
                 msg->time -= diff;
             else
                 msg->started = 1;
-            // display it
-            return msg;
+        } else {
+            // kill the message
+            talloc_free(msg);
+            msg = NULL;
+            mpctx->osd_msg_stack = NULL;
         }
-        // kill the message
-        talloc_free(msg);
-        mpctx->osd_msg_stack = NULL;
     }
-    // Nothing found
-    return NULL;
+    if (msg)
+        mpctx->sleeptime = MPMIN(mpctx->sleeptime, msg->time);
+    return msg;
 }
 
 // type: mp_osd_font_codepoints, ASCII, or OSD_BAR_*

player/playloop.c

@@ -52,8 +52,6 @@
 #include "screenshot.h"
 #include "command.h"
 
-#define WAKEUP_PERIOD 0.5
-
 static const char av_desync_help_text[] =
 "\n\n"
 "           *************************************************\n"
@@ -644,10 +642,11 @@ static void handle_heartbeat_cmd(struct MPContext *mpctx)
     struct MPOpts *opts = mpctx->opts;
     if (opts->heartbeat_cmd && !mpctx->paused) {
         double now = mp_time_sec();
-        if (now - mpctx->last_heartbeat > opts->heartbeat_interval) {
-            mpctx->last_heartbeat = now;
+        if (mpctx->next_heartbeat <= now) {
+            mpctx->next_heartbeat = now + opts->heartbeat_interval;
             system(opts->heartbeat_cmd);
         }
+        mpctx->sleeptime = MPMIN(mpctx->sleeptime, mpctx->next_heartbeat - now);
     }
 }
 
@@ -660,17 +659,20 @@ static void handle_cursor_autohide(struct MPContext *mpctx)
         return;
 
     bool mouse_cursor_visible = mpctx->mouse_cursor_visible;
+    double now = mp_time_sec();
 
     unsigned mouse_event_ts = mp_input_get_mouse_event_counter(mpctx->input);
     if (mpctx->mouse_event_ts != mouse_event_ts) {
         mpctx->mouse_event_ts = mouse_event_ts;
-        mpctx->mouse_timer =
-            mp_time_sec() + opts->cursor_autohide_delay / 1000.0;
+        mpctx->mouse_timer = now + opts->cursor_autohide_delay / 1000.0;
         mouse_cursor_visible = true;
     }
 
-    if (mp_time_sec() >= mpctx->mouse_timer)
+    if (mpctx->mouse_timer > now) {
+        mpctx->sleeptime = MPMIN(mpctx->sleeptime, mpctx->mouse_timer - now);
+    } else {
         mouse_cursor_visible = false;
+    }
 
     if (opts->cursor_autohide_delay == -1)
         mouse_cursor_visible = true;
@@ -879,13 +881,7 @@ static double timing_sleep(struct MPContext *mpctx, double time_frame)
 
 static double get_wakeup_period(struct MPContext *mpctx)
 {
-    /* Even if we can immediately wake up in response to most input events,
-     * there are some timers which are not registered to the event loop
-     * and need to be checked periodically (like automatic mouse cursor hiding).
-     * OSD content updates behave similarly. Also some uncommon input devices
-     * may not have proper FD event support.
-     */
-    double sleeptime = WAKEUP_PERIOD;
+    double sleeptime = 100.0; // infinite for all practical purposes
 
 #if !HAVE_POSIX_SELECT
     // No proper file descriptor event handling; keep waking up to poll input
@@ -906,7 +902,6 @@ void run_playloop(struct MPContext *mpctx)
     bool audio_left = false, video_left = false;
     double endpts = get_play_end_pts(mpctx);
     bool end_is_chapter = false;
-    double sleeptime = get_wakeup_period(mpctx);
     bool was_restart = mpctx->restart_playback;
     bool new_frame_shown = false;
 
@@ -1010,7 +1005,7 @@ void run_playloop(struct MPContext *mpctx)
         }
 
         if (r != 2 && !mpctx->playing_last_frame) {
-            sleeptime = 0;
+            mpctx->sleeptime = 0;
             break;
         }
 
@@ -1052,10 +1047,10 @@ void run_playloop(struct MPContext *mpctx)
 
         double vsleep = mpctx->time_frame - vo->flip_queue_offset;
         if (vsleep > 0.050) {
-            sleeptime = MPMIN(sleeptime, vsleep - 0.040);
+            mpctx->sleeptime = MPMIN(mpctx->sleeptime, vsleep - 0.040);
             break;
         }
-        sleeptime = 0;
+        mpctx->sleeptime = 0;
         mpctx->playing_last_frame = false;
 
         // last frame case (don't set video_left - consider format changes)
@@ -1245,19 +1240,21 @@ void run_playloop(struct MPContext *mpctx)
 
     }
 
-    if (!mpctx->stop_play) {
-        if (mpctx->restart_playback)
-            sleeptime = 0;
-        if (sleeptime > 0) {
-            if (handle_osd_redraw(mpctx))
-                sleeptime = 0;
-        }
-        if (sleeptime > 0) {
-            MP_STATS(mpctx, "start sleep");
-            mp_input_get_cmd(mpctx->input, sleeptime * 1000, true);
-            MP_STATS(mpctx, "end sleep");
-        }
+    if (mpctx->stop_play)
+        mpctx->sleeptime = 0;
+
+    if (mpctx->restart_playback)
+        mpctx->sleeptime = 0;
+
+    if (mpctx->sleeptime > 0 && handle_osd_redraw(mpctx))
+        mpctx->sleeptime = 0;
+
+    if (mpctx->sleeptime > 0) {
+        MP_STATS(mpctx, "start sleep");
+        mp_input_get_cmd(mpctx->input, mpctx->sleeptime * 1000, true);
+        MP_STATS(mpctx, "end sleep");
     }
+    mpctx->sleeptime = get_wakeup_period(mpctx);
 
     handle_pause_on_low_cache(mpctx);