[project @ 1999-08-25 16:11:43 by simonmar]

[ghc-hetmet.git] / ghc / rts / Weak.c

diff --git a/ghc/rts/Weak.c b/ghc/rts/Weak.c
index db97ecc..4f8159f 100644 (file)
--- a/ghc/rts/Weak.c
+++ b/ghc/rts/Weak.c
@@ -1,12 +1,15 @@
 /* -----------------------------------------------------------------------------
- * $Id: Weak.c,v 1.2 1998/12/02 13:29:01 simonm Exp $
+ * $Id: Weak.c,v 1.11 1999/07/06 15:05:49 sof Exp $
  *
- * Weak pointers / finalisers
+ * (c) The GHC Team, 1998-1999
+ *
+ * Weak pointers / finalizers
  *
  * ---------------------------------------------------------------------------*/
 
 #include "Rts.h"
 #include "RtsAPI.h"
+#include "SchedAPI.h"
 #include "RtsFlags.h"
 #include "Weak.h"
 #include "Storage.h"
@@ -14,55 +17,57 @@
 StgWeak *weak_ptr_list;
 
 /*
- * finaliseWeakPointersNow() is called just before the system is shut
- * down.  It runs the finaliser for each weak pointer still in the
+ * finalizeWeakPointersNow() is called just before the system is shut
+ * down.  It runs the finalizer for each weak pointer still in the
  * system.
+ *
+ * Careful here - rts_evalIO might cause a garbage collection, which
+ * might change weak_ptr_list.  Must re-load weak_ptr_list each time
+ * around the loop.
  */
 
 void
-finaliseWeakPointersNow(void)
+finalizeWeakPointersNow(void)
 {
   StgWeak *w;
-
-  for (w = weak_ptr_list; w; w = w->link) {
-    IF_DEBUG(weak,fprintf(stderr,"Finalising weak pointer at %p\n", w));
+  
+  while ((w = weak_ptr_list)) {
+    weak_ptr_list = w->link;
+    IF_DEBUG(weak,fprintf(stderr,"Finalising weak pointer at %p -> %p\n", w, w->key));
     w->header.info = &DEAD_WEAK_info;
-    rts_evalIO(w->finaliser,NULL);
+    if (w->finalizer != &NO_FINALIZER_closure) {
+      rts_evalIO(w->finalizer,NULL);
+    }
   }
 } 
 
 /*
- * scheduleFinalisers() is called on the list of weak pointers found
+ * scheduleFinalizers() is called on the list of weak pointers found
  * to be dead after a garbage collection.  It overwrites each object
- * with DEAD_WEAK, and creates a new thread for the finaliser.
+ * with DEAD_WEAK, and creates a new thread for the finalizer.
+ *
+ * This function is called just after GC.  The weak pointers on the
+ * argument list are those whose keys were found to be not reachable,
+ * however the value and finalizer fields have by now been marked live.
+ * The weak pointer object itself may not be alive - i.e. we may be
+ * looking at either an object in from-space or one in to-space.  It
+ * doesn't really matter either way.
  */
 
 void
-scheduleFinalisers(StgWeak *list)
+scheduleFinalizers(StgWeak *list)
 {
   StgWeak *w;
   
   for (w = list; w; w = w->link) {
-    IF_DEBUG(weak,fprintf(stderr,"Finalising weak pointer at %p\n", w));
+    IF_DEBUG(weak,fprintf(stderr,"Finalising weak pointer at %p -> %p\n", w, w->key));
+    if (w->finalizer != &NO_FINALIZER_closure) {
 #ifdef INTERPRETER
-    createGenThread(RtsFlags.GcFlags.initialStkSize, w->finaliser);
+      createGenThread(RtsFlags.GcFlags.initialStkSize, w->finalizer);
 #else
-    createIOThread(RtsFlags.GcFlags.initialStkSize, w->finaliser);
+      createIOThread(RtsFlags.GcFlags.initialStkSize, w->finalizer);
 #endif
+    }
     w->header.info = &DEAD_WEAK_info;
   }
 }
-
-void
-markWeakList(void)
-{
-  StgWeak *w, **last_w;
-
-  last_w = &weak_ptr_list;
-  for (w = weak_ptr_list; w; w = w->link) {
-    w = (StgWeak *)MarkRoot((StgClosure *)w);
-    *last_w = w;
-    last_w = &(w->link);
-  }
-}
-