/* -----------------------------------------------------------------------------
- * $Id: Weak.c,v 1.5 1999/02/01 18:05:35 simonm Exp $
+ * $Id: Weak.c,v 1.29 2003/03/26 17:43:05 sof Exp $
*
- * Weak pointers / finalisers
+ * (c) The GHC Team, 1998-1999
+ *
+ * Weak pointers / finalizers
*
* ---------------------------------------------------------------------------*/
+#include "PosixSource.h"
+#define COMPILING_RTS_MAIN
#include "Rts.h"
-#include "RtsAPI.h"
+#include "SchedAPI.h"
#include "RtsFlags.h"
#include "Weak.h"
#include "Storage.h"
+#include "Schedule.h"
+#include "Prelude.h"
+#include "RtsAPI.h"
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 -> %p\n", w, w->key));
- w->header.info = &DEAD_WEAK_info;
- if (w->finaliser != &NO_FINALISER_info) {
- rts_evalIO(w->finaliser,NULL);
+
+#if defined(RTS_SUPPORTS_THREADS)
+ rts_lock();
+#endif
+ while ((w = weak_ptr_list)) {
+ weak_ptr_list = w->link;
+ if (w->header.info != &stg_DEAD_WEAK_info) {
+ w->header.info = &stg_DEAD_WEAK_info;
+ IF_DEBUG(weak,fprintf(stderr,"Finalising weak pointer at %p -> %p\n", w, w->key));
+ if (w->finalizer != &stg_NO_FINALIZER_closure) {
+#if defined(RTS_SUPPORTS_THREADS)
+ rts_evalIO(w->finalizer,NULL);
+ rts_unlock();
+ rts_lock();
+#else
+ rts_mainLazyIO(w->finalizer,NULL);
+#endif
+ }
}
}
+#if defined(RTS_SUPPORTS_THREADS)
+ rts_unlock();
+#endif
}
/*
- * 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 to run the pending finalizers.
+ *
+ * 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.
+ *
+ * Pre-condition: sched_mutex _not_ held.
*/
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 -> %p\n", w, w->key));
- if (w->finaliser != &NO_FINALISER_info) {
-#ifdef INTERPRETER
- createGenThread(RtsFlags.GcFlags.initialStkSize, w->finaliser);
-#else
- createIOThread(RtsFlags.GcFlags.initialStkSize, w->finaliser);
+ StgWeak *w;
+ StgTSO *t;
+ StgMutArrPtrs *arr;
+ nat n;
+
+ // count number of finalizers, and kill all the weak pointers first...
+ n = 0;
+ for (w = list; w; w = w->link) {
+
+ // Better not be a DEAD_WEAK at this stage; the garbage
+ // collector removes DEAD_WEAKs from the weak pointer list.
+ ASSERT(w->header.info != &stg_DEAD_WEAK_info);
+
+ if (w->finalizer != &stg_NO_FINALIZER_closure) {
+ n++;
+ }
+
+#ifdef PROFILING
+ // A weak pointer is inherently used, so we do not need to call
+ // LDV_recordDead().
+ //
+ // Furthermore, when PROFILING is turned on, dead weak
+ // pointers are exactly as large as weak pointers, so there is
+ // no need to fill the slop, either. See stg_DEAD_WEAK_info
+ // in StgMiscClosures.hc.
#endif
+ SET_HDR(w, &stg_DEAD_WEAK_info, w->header.prof.ccs);
}
- w->header.info = &DEAD_WEAK_info;
- }
-}
+
+ // No finalizers to run?
+ if (n == 0) return;
-void
-markWeakList(void)
-{
- StgWeak *w, **last_w;
+ IF_DEBUG(weak,fprintf(stderr,"weak: batching %d finalizers\n", n));
- 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);
- }
-}
+ arr = (StgMutArrPtrs *)allocate(sizeofW(StgMutArrPtrs) + n);
+ TICK_ALLOC_PRIM(sizeofW(StgMutArrPtrs), n, 0);
+ SET_HDR(arr, &stg_MUT_ARR_PTRS_FROZEN_info, CCS_SYSTEM);
+ arr->ptrs = n;
+ n = 0;
+ for (w = list; w; w = w->link) {
+ if (w->finalizer != &stg_NO_FINALIZER_closure) {
+ arr->payload[n] = w->finalizer;
+ n++;
+ }
+ }
+
+ t = createIOThread(RtsFlags.GcFlags.initialStkSize,
+ rts_apply(
+ rts_apply(
+ (StgClosure *)runFinalizerBatch_closure,
+ rts_mkInt(n)),
+ (StgClosure *)arr)
+ );
+ scheduleThread(t);
+}