Make sure draw_idle is stopped in all cases

Previously, compton fails to stop draw_idle in some cases when sw_opti
is enabled.

sw_opti is a feature that limits the draw frequence to vblank frequence.
It adds a delay to drawing when the screen is updated more frequently
than the vblank frequence. However when the delay is not used (i.e. the
screen is updated infrequent enough), compton will start drawing the
frame directly without using the delay. And specically in this case,
compton will fail to stop the draw_idle, causing a callback to be called
once per loop of the mainloop, resulting in high CPU usage.

Fixes chjj#92

Signed-off-by: Yuxuan Shui <[email protected]>

src/compton.c

@@ -2482,12 +2482,16 @@ static void
 delayed_draw_callback(EV_P_ ev_idle *w, int revents) {
   // This function is only used if we are using --swopti
   session_t *ps = session_ptr(w, draw_idle);
-  if (ev_is_active(&ps->delayed_draw_timer))
-    return;
+  assert(ps->redraw_needed);
+  assert(!ev_is_active(&ps->delayed_draw_timer));
 
   double delay = swopti_handle_timeout(ps);
-  if (delay < 1e-6)
+  if (delay < 1e-6) {
+    if (!ps->o.benchmark) {
+      ev_idle_stop(ps->loop, &ps->draw_idle);
+    }
     return _draw_callback(EV_A_ ps, revents);
+  }
 
   // This is a little bit hacky. When we get to this point in code, we need
   // to update the screen , but we will only be updating after a delay, So