Re: Reachable killed buffers

[Dmitry Antipov <dmantipov@yandex.ru>]

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On 09/12/2012 06:15 PM, martin rudalics wrote:

>> Perhaps there's something smarter, but I hope the dumb answer
>> is good enough....
>
> ... it is ;-)

What if we join marking and killed buffer removal? Thus we
can avoid the infinite-loop on circularity and double walking
through the list (one for removal and one for marking)...

Dmitry

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=== modified file 'src/alloc.c'
--- src/alloc.c	2012-09-11 20:35:23 +0000
+++ src/alloc.c	2012-09-12 15:53:01 +0000
@@ -5865,16 +5865,16 @@
     mark_buffer (buffer->base_buffer);
 }
 
-/* Remove killed buffers or items whose car is a killed buffer
-   from LIST and return changed LIST.  Called during GC.  */
+/* Remove killed buffers or items whose car is a killed buffer from
+   LIST, and mark other items. Return changed LIST, which is marked.  */
 
 static Lisp_Object
-discard_killed_buffers (Lisp_Object list)
+mark_discard_killed_buffers (Lisp_Object list)
 {
   Lisp_Object *prev = &list;
-  Lisp_Object tail;
+  Lisp_Object tail = list;
 
-  for (tail = list; CONSP (tail); tail = XCDR (tail))
+  while (CONSP (tail) && !CONS_MARKED_P (XCONS (tail)))
     {
       Lisp_Object tem = XCAR (tail);
       if (CONSP (tem))
@@ -5882,7 +5882,12 @@
       if (BUFFERP (tem) && !BUFFER_LIVE_P (XBUFFER (tem)))
 	*prev = XCDR (tail);
       else
-	prev = &XCDR_AS_LVALUE (tail);
+	{
+	  CONS_MARK (tail);
+	  mark_object (XCAR (tail));
+	  prev = &XCDR_AS_LVALUE (tail);
+	}
+      tail = XCDR (tail);
     }
   return list;
 }
@@ -6030,7 +6035,7 @@
 		 store_frame_param.  For dead frames, we do it here in
 		 attempt to help GC to reclaim killed buffers faster.  */
 	      if (!FRAME_LIVE_P (f))
-		fset_buffer_list (f, discard_killed_buffers (f->buffer_list));
+		fset_buffer_list (f, mark_discard_killed_buffers (f->buffer_list));
 
 	      mark_vectorlike (ptr);
 	      mark_face_cache (f->face_cache);
@@ -6048,9 +6053,9 @@
 	      if (leaf && NILP (w->buffer))
 		{
 		  wset_prev_buffers
-		    (w, discard_killed_buffers (w->prev_buffers));
+		    (w, mark_discard_killed_buffers (w->prev_buffers));
 		  wset_next_buffers
-		    (w, discard_killed_buffers (w->next_buffers));
+		    (w, mark_discard_killed_buffers (w->next_buffers));
 		}
 
 	      mark_vectorlike (ptr);