Avoid X11 error bad drawable when drawable changes while displaying.

At least two threads operate on the drawable -- the video output thread and
the xine-ui gui thread. When xine-ui changes the drawable while the output
thread is displaying a frame it is likely that the video output thread
triggers the X11 error bad drawable. Usually XLockDisplay() is used to
synchronize these threads but it causes too much impact and should only be
used to implement short atomic operations. In this case scheduling two
fields of a frame for displaying may take at least one field duration which
is quite a long time. Therefore a separate mutex is used for synchronizing
those threads.

1 files changed, 13 insertions, 0 deletions

diff --git a/src/video_out/video_out_vdpau.c b/src/video_out/video_out_vdpau.c
index 852b4f856..2df846db3 100644
--- a/src/video_out/video_out_vdpau.c
+++ b/src/video_out/video_out_vdpau.c
@@ -276,6 +276,7 @@ typedef struct {
   Display           *display;
   int                screen;
   Drawable           drawable;
+  pthread_mutex_t    drawable_lock;
 
   config_values_t   *config;
 
@@ -1563,6 +1564,7 @@ static void vdpau_display_frame (vo_driver_t *this_gen, vo_frame_t *frame_gen)
   uint32_t mix_h = this->video_mixer_height;
   VdpTime stream_speed;
 
+  pthread_mutex_lock(&this->drawable_lock); /* protect drawble from being changed */
 
   if(this->reinit_needed)
     vdpau_reinit(this_gen);
@@ -1621,6 +1623,7 @@ static void vdpau_display_frame (vo_driver_t *this_gen, vo_frame_t *frame_gen)
     /* unknown format */
     fprintf(stderr, "vo_vdpau: got an unknown image -------------\n" );
     frame->vo_frame.free( &frame->vo_frame );
+    pthread_mutex_unlock(&this->drawable_lock); /* allow changing drawable again */
     return;
   }
 
@@ -1826,6 +1829,8 @@ static void vdpau_display_frame (vo_driver_t *this_gen, vo_frame_t *frame_gen)
     vdpau_backup_frame( this_gen, frame_gen );
   else /* do not release past frame if paused, it will be used for redrawing */
     frame->vo_frame.free( &frame->vo_frame );
+
+  pthread_mutex_unlock(&this->drawable_lock); /* allow changing drawable again */
 }
 
 
@@ -1957,10 +1962,12 @@ static int vdpau_gui_data_exchange (vo_driver_t *this_gen, int data_type, void *
 #ifdef LOCKDISPLAY
         XLockDisplay( this->display );
 #endif
+        pthread_mutex_lock(&this->drawable_lock); /* wait for other thread which is currently displaying */
         int previous = this->current_output_surface - 1;
         if ( previous < 0 )
           previous = NOUTPUTSURFACE - 1;
         vdp_queue_display( vdp_queue, this->output_surface[previous], 0, 0, 0 );
+        pthread_mutex_unlock(&this->drawable_lock);
 #ifdef LOCKDISPLAY
         XUnlockDisplay( this->display );
 #endif
@@ -1973,12 +1980,14 @@ static int vdpau_gui_data_exchange (vo_driver_t *this_gen, int data_type, void *
 #ifdef LOCKDISPLAY
       XLockDisplay( this->display );
 #endif
+      pthread_mutex_lock(&this->drawable_lock); /* wait for other thread which is currently displaying */
       this->drawable = (Drawable) data;
       vdp_queue_destroy( vdp_queue );
       vdp_queue_target_destroy( vdp_queue_target );
       st = vdp_queue_target_create_x11( vdp_device, this->drawable, &vdp_queue_target );
       if ( st != VDP_STATUS_OK ) {
         fprintf(stderr, "vo_vdpau: FATAL !! Can't recreate presentation queue target after drawable change !!\n" );
+        pthread_mutex_unlock(&this->drawable_lock);
 #ifdef LOCKDISPLAY
         XUnlockDisplay( this->display );
 #endif
@@ -1987,12 +1996,14 @@ static int vdpau_gui_data_exchange (vo_driver_t *this_gen, int data_type, void *
       st = vdp_queue_create( vdp_device, vdp_queue_target, &vdp_queue );
       if ( st != VDP_STATUS_OK ) {
         fprintf(stderr, "vo_vdpau: FATAL !! Can't recreate presentation queue after drawable change !!\n" );
+        pthread_mutex_unlock(&this->drawable_lock);
 #ifdef LOCKDISPLAY
         XUnlockDisplay( this->display );
 #endif
         break;
       }
       vdp_queue_set_background_color( vdp_queue, &this->back_color );
+      pthread_mutex_unlock(&this->drawable_lock);
 #ifdef LOCKDISPLAY
       XUnlockDisplay( this->display );
 #endif
@@ -2074,6 +2085,7 @@ static void vdpau_dispose (vo_driver_t *this_gen)
   if ( (vdp_device != VDP_INVALID_HANDLE) && vdp_device_destroy )
     vdp_device_destroy( vdp_device );
 
+  pthread_mutex_destroy(&this->drawable_lock);
   free (this);
 }
 
@@ -2280,6 +2292,7 @@ static vo_driver_t *vdpau_open_plugin (video_driver_class_t *class_gen, const vo
   this->display       = visual->display;
   this->screen        = visual->screen;
   this->drawable      = visual->d;
+  pthread_mutex_init(&this->drawable_lock, 0);
 
   _x_vo_scale_init(&this->sc, 1, 0, config);
   this->sc.frame_output_cb  = visual->frame_output_cb;