DF behaviour: Allow zero-horizon windows/views

libworkstream_df/reuse.c

@@ -141,6 +141,9 @@ void __built_in_wstream_df_prepare_data(void* v)
   wstream_df_view_p out_view = v;
   int force_reuse = 0;
 
+  if (!out_view->horizon)
+    return;
+
   /* View of a direct consumer of the task to be executed */
   wstream_df_view_p consumer_view = out_view->consumer_view;
 

libworkstream_df/wstream_df.c

@@ -352,6 +352,8 @@ void update_numa_nodes_of_views(wstream_df_thread_p cthread, wstream_df_frame_p
 static inline void
 tdecrease_n (void *data, size_t n, bool is_write)
 {
+  if (!n)
+    return;
 
   wstream_df_frame_p fp = (wstream_df_frame_p) data;
   wstream_df_thread_p cthread = current_thread;
@@ -718,6 +720,13 @@ wstream_df_resolve_dependences (void *v, void *s, bool is_read_view_p)
   wstream_df_frame_p fp = view->owner;
   int defer_further = 0;
 
+  if (!view->horizon)
+  {
+    if (!is_read_view_p)
+      tdecrease_n (fp, 1, 0);
+    return;
+  }
+
   if(is_read_view_p)
     check_add_view_to_chain(&fp->input_view_chain, view);
   else