picture_fifo: add picture_fifo_Peek

include/vlc_picture_fifo.h

@@ -56,6 +56,13 @@ VLC_API void picture_fifo_Delete( picture_fifo_t * );
  */
 VLC_API picture_t * picture_fifo_Pop( picture_fifo_t * ) VLC_USED;
 
+/**
+ * It peeks the front picture_t of the fifo.
+ *
+ * If the fifo is empty, it return NULL without waiting.
+ */
+VLC_API picture_t * picture_fifo_Peek( picture_fifo_t * ) VLC_USED;
+
 /**
  * It returns whether the fifo is empty or not.
  */

src/libvlccore.sym

@@ -314,6 +314,7 @@ picture_fifo_Delete
 picture_fifo_Flush
 picture_fifo_New
 picture_fifo_IsEmpty
+picture_fifo_Peek
 picture_fifo_Pop
 picture_fifo_Push
 picture_New

src/misc/picture_fifo.c

@@ -67,6 +67,14 @@ picture_t *picture_fifo_Pop(picture_fifo_t *fifo)
 
     return picture;
 }
+picture_t *picture_fifo_Peek(picture_fifo_t *fifo)
+{
+    vlc_mutex_lock(&fifo->lock);
+    picture_t *picture = vlc_picture_chain_PeekFront( &fifo->pics );
+    vlc_mutex_unlock(&fifo->lock);
+
+    return picture;
+}
 bool picture_fifo_IsEmpty(picture_fifo_t *fifo)
 {
     vlc_mutex_lock(&fifo->lock);