Reorganisation of the source tree

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

diff --git a/rts/Weak.c b/rts/Weak.c
new file mode 100644 (file)
index 0000000..f010395
--- /dev/null
+++ b/rts/Weak.c
@@ -0,0 +1,97 @@
+/* -----------------------------------------------------------------------------
+ *
+ * (c) The GHC Team, 1998-1999
+ *
+ * Weak pointers / finalizers
+ *
+ * ---------------------------------------------------------------------------*/
+
+#include "PosixSource.h"
+#define COMPILING_RTS_MAIN
+#include "Rts.h"
+#include "RtsUtils.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;
+
+/*
+ * 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 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
+scheduleFinalizers(Capability *cap, StgWeak *list)
+{
+    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);
+    }
+       
+    // No finalizers to run?
+    if (n == 0) return;
+
+    IF_DEBUG(weak,debugBelch("weak: batching %d finalizers\n", n));
+
+    arr = (StgMutArrPtrs *)allocateLocal(cap, 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(cap, 
+                      RtsFlags.GcFlags.initialStkSize, 
+                      rts_apply(cap,
+                          rts_apply(cap,
+                              (StgClosure *)runFinalizerBatch_closure,
+                              rts_mkInt(cap,n)), 
+                          (StgClosure *)arr)
+       );
+    scheduleThread(cap,t);
+}