embedded snapshot: use condition variable

Let's see if this fits courmisch's standards...

include/vlc_vout.h

@@ -714,6 +714,8 @@ typedef struct snapshot_t {
   int i_height;      /* In pixels */
   int i_datasize;    /* In bytes */
   mtime_t date;      /* Presentation time */
+  vlc_cond_t p_condvar;
+  vlc_mutex_t p_mutex;
 } snapshot_t;
 
 /**@}*/

src/control/mediacontrol_audio_video.c

@@ -56,7 +56,6 @@ mediacontrol_snapshot( mediacontrol_Instance *self,
                        mediacontrol_Exception *exception )
 {
     (void)a_position;
-    vlc_object_t* p_cache;
     vout_thread_t* p_vout;
     input_thread_t *p_input;
     mediacontrol_RGBPicture *p_pic = NULL;
@@ -67,6 +66,13 @@ mediacontrol_snapshot( mediacontrol_Instance *self,
     libvlc_exception_init( &ex );
     mediacontrol_exception_init( exception );
 
+
+    p_snapshot = malloc( sizeof( snapshot_t ) );
+    if( ! p_snapshot )
+    {
+        RAISE_NULL( mediacontrol_InternalException, "Cannot allocate snapshot" );
+    }
+
     p_input = libvlc_get_input_thread( self->p_media_player, &ex );
     if( ! p_input )
     {
@@ -79,26 +85,49 @@ mediacontrol_snapshot( mediacontrol_Instance *self,
     {
         RAISE_NULL( mediacontrol_InternalException, "No video output" );
     }
-    p_cache = vlc_object_create( p_input, sizeof( vlc_object_t ) );
-    if( p_cache == NULL )
-    {
-        vlc_object_release( p_vout );
-        vlc_object_release( p_input );
-        RAISE_NULL( mediacontrol_InternalException, "Out of memory" );
-    }
-    snprintf( path, 255, "object:%p", p_cache );
+
+    /* TODO:
+   vlc_mutex_lock (&lock);
+   mutex_cleanup_push (&lock); // release the mutex in case of cancellation
+
+   while (!foobar)
+       vlc_cond_wait (&wait, &lock);
+
+   --- foobar is now true, do something about it here --
+
+   vlc_cleanup_run (); // release the mutex
+    */
+
+    snprintf( path, 255, "object:%p", p_snapshot );
     var_SetString( p_vout, "snapshot-path", path );
     var_SetString( p_vout, "snapshot-format", "png" );
 
-    vlc_object_lock( p_cache );
+    vlc_mutex_init( &p_snapshot->p_mutex );
+    vlc_cond_init( &p_snapshot->p_condvar );
+
+    vlc_mutex_lock( &p_snapshot->p_mutex );
+    mutex_cleanup_push( &p_snapshot->p_mutex );
+
+    /* Use p_snapshot address as sentinel against spurious vlc_object_wait wakeups.
+
+       If a legitimate wakeup occurs, then p_snapshot->p_data will hold either
+       NULL (in case of error) or a pointer to valid data. */
+    p_snapshot->p_data = ( char* )p_snapshot;
+
     vout_Control( p_vout, VOUT_SNAPSHOT );
+    while ( p_snapshot->p_data == ( char* )p_snapshot )
+    {
+        vlc_cond_wait( &p_snapshot->p_condvar, &p_snapshot->p_mutex );
+    }
+    vlc_cleanup_pop();
+
     vlc_object_release( p_vout );
 
-    p_snapshot = ( snapshot_t* ) p_cache->p_private;
-    vlc_object_unlock( p_cache );
-    vlc_object_release( p_cache );
+    vlc_mutex_unlock( &p_snapshot->p_mutex );
+    vlc_cond_destroy( &p_snapshot->p_condvar );
+    vlc_mutex_destroy( &p_snapshot->p_mutex );
 
-    if( p_snapshot )
+    if( p_snapshot->p_data )
     {
         /* Note: p_snapshot->p_data is directly used, not copied. Thus
            do not free it here. */

src/video_output/vout_intf.c

@@ -638,13 +638,12 @@ int vout_Snapshot( vout_thread_t *p_vout, picture_t *p_pic )
      */
     if( b_embedded_snapshot )
     {
-        vlc_object_t* p_dest = p_obj;
         block_t *p_block;
-        snapshot_t *p_snapshot;
+        snapshot_t *p_snapshot = p_obj;
         size_t i_size;
 
-	vlc_object_lock( p_dest );
-        p_dest->p_private = NULL;
+	vlc_mutex_lock( &p_snapshot->p_mutex );
+	p_snapshot->p_data = NULL;
 
         /* Save the snapshot to a memory zone */
         p_block = image_Write( p_image, p_pic, &fmt_in, &fmt_out );
@@ -652,23 +651,11 @@ int vout_Snapshot( vout_thread_t *p_vout, picture_t *p_pic )
         {
             msg_Err( p_vout, "Could not get snapshot" );
             image_HandlerDelete( p_image );
-            vlc_object_signal_unlocked( p_dest );
-	    vlc_object_unlock( p_dest );
+	    vlc_cond_signal( &p_snapshot->p_condvar );
+	    vlc_mutex_unlock( &p_snapshot->p_mutex );
             return VLC_EGENERIC;
         }
 
-        /* Copy the p_block data to a snapshot structure */
-        /* FIXME: get the timestamp */
-        p_snapshot = malloc( sizeof( snapshot_t ) );
-        if( !p_snapshot )
-        {
-            block_Release( p_block );
-            image_HandlerDelete( p_image );
-            vlc_object_signal_unlocked( p_dest );
-	    vlc_object_unlock( p_dest );
-            return VLC_ENOMEM;
-        }
-
         i_size = p_block->i_buffer;
 
         p_snapshot->i_width = fmt_out.i_width;
@@ -679,21 +666,18 @@ int vout_Snapshot( vout_thread_t *p_vout, picture_t *p_pic )
         if( !p_snapshot->p_data )
         {
             block_Release( p_block );
-            free( p_snapshot );
             image_HandlerDelete( p_image );
-            vlc_object_signal_unlocked( p_dest );
-	    vlc_object_unlock( p_dest );
+	    vlc_cond_signal( &p_snapshot->p_condvar );
+	    vlc_mutex_unlock( &p_snapshot->p_mutex );
             return VLC_ENOMEM;
         }
         memcpy( p_snapshot->p_data, p_block->p_buffer, p_block->i_buffer );
 
-        p_dest->p_private = p_snapshot;
-
         block_Release( p_block );
 
         /* Unlock the object */
-        vlc_object_signal_unlocked( p_dest );
-	vlc_object_unlock( p_dest );
+	vlc_cond_signal( &p_snapshot->p_condvar );
+	vlc_mutex_unlock( &p_snapshot->p_mutex );
 
         image_HandlerDelete( p_image );
         return VLC_SUCCESS;