[project @ 2004-08-22 15:50:39 by panne]

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

diff --git a/ghc/rts/Stable.c b/ghc/rts/Stable.c
index 5cf9c28..815bac7 100644 (file)
--- a/ghc/rts/Stable.c
+++ b/ghc/rts/Stable.c
@@ -1,16 +1,18 @@
 /* -----------------------------------------------------------------------------
- * $Id: Stable.c,v 1.20 2002/04/09 12:56:36 simonmar Exp $
+ * $Id: Stable.c,v 1.29 2004/08/22 15:50:42 panne Exp $
  *
- * (c) The GHC Team, 1998-1999
+ * (c) The GHC Team, 1998-2002
  *
  * Stable names and stable pointers.
  *
  * ---------------------------------------------------------------------------*/
 
+// Make static versions of inline functions in Stable.h:
+#define RTS_STABLE_C
+
 #include "PosixSource.h"
 #include "Rts.h"
 #include "Hash.h"
-#include "StablePriv.h"
 #include "RtsUtils.h"
 #include "Storage.h"
 #include "RtsAPI.h"
@@ -70,27 +72,12 @@
   There may be additional functions on the C side to allow evaluation,
   application, etc of a stable pointer.
 
-  When Haskell calls C, it normally just passes over primitive integers,
-  floats, bools, strings, etc.  This doesn't cause any problems at all
-  for garbage collection because the act of passing them makes a copy
-  from the heap, stack or wherever they are onto the C-world stack.
-  However, if we were to pass a heap object such as a (Haskell) @String@
-  and a garbage collection occured before we finished using it, we'd run
-  into problems since the heap object might have been moved or even
-  deleted.
-
-  So, if a C call is able to cause a garbage collection or we want to
-  store a pointer to a heap object between C calls, we must be careful
-  when passing heap objects. Our solution is to keep a table of all
-  objects we've given to the C-world and to make sure that the garbage
-  collector collects these objects --- updating the table as required to
-  make sure we can still find the object.
 */
 
-snEntry *stable_ptr_table;
-snEntry *stable_ptr_free;
+snEntry *stable_ptr_table = NULL;
+static snEntry *stable_ptr_free = NULL;
 
-unsigned int SPT_size;
+static unsigned int SPT_size = 0;
 
 /* This hash table maps Haskell objects to stable names, so that every
  * call to lookupStableName on a given object will return the same
@@ -125,11 +112,11 @@ unsigned int SPT_size;
  * to the weight stored in the table entry.
  * */
 
-HashTable *addrToStableHash;
+static HashTable *addrToStableHash = NULL;
 
 #define INIT_SPT_SIZE 64
 
-static inline void
+STATIC_INLINE void
 initFreeList(snEntry *table, nat n, snEntry *free)
 {
   snEntry *p;
@@ -147,12 +134,9 @@ initFreeList(snEntry *table, nat n, snEntry *free)
 void
 initStablePtrTable(void)
 {
-  /* the table will be allocated the first time makeStablePtr is
-   * called */
-  stable_ptr_table = NULL;
-  stable_ptr_free  = NULL;
-  addrToStableHash = NULL;
-  SPT_size = 0;
+    // Nothing to do:
+    // the table will be allocated the first time makeStablePtr is
+    // called, and we want the table to persist through multiple inits.
 }
 
 /*
@@ -180,6 +164,7 @@ StgWord
 lookupStableName(StgPtr p)
 {
   StgWord sn;
+  void* sn_tmp;
 
   if (stable_ptr_free == NULL) {
     enlargeStablePtrTable();
@@ -190,7 +175,8 @@ lookupStableName(StgPtr p)
    */
   p = (StgPtr)removeIndirections((StgClosure*)p);
 
-  (void *)sn = lookupHashTable(addrToStableHash,(W_)p);
+  sn_tmp = lookupHashTable(addrToStableHash,(W_)p);
+  sn = (StgWord)sn_tmp;
   
   if (sn != 0) {
     ASSERT(stable_ptr_table[sn].addr == p);
@@ -198,7 +184,7 @@ lookupStableName(StgPtr p)
     return sn;
   } else {
     sn = stable_ptr_free - stable_ptr_table;
-    (P_)stable_ptr_free  = stable_ptr_free->addr;
+    stable_ptr_free  = (snEntry*)(stable_ptr_free->addr);
     stable_ptr_table[sn].ref = 0;
     stable_ptr_table[sn].addr = p;
     stable_ptr_table[sn].sn_obj = NULL;
@@ -212,7 +198,7 @@ lookupStableName(StgPtr p)
   }
 }
 
-static inline void
+STATIC_INLINE void
 freeStableName(snEntry *sn)
 {
   ASSERT(sn->sn_obj == NULL);
@@ -245,7 +231,7 @@ freeStablePtr(StgStablePtr sp)
     // If this entry has no StableName attached, then just free it
     // immediately.  This is important; it might be a while before the
     // next major GC which actually collects the entry.
-    if (sn->sn_obj == NULL) {
+    if (sn->sn_obj == NULL && sn->ref == 0) {
        freeStableName(sn);
     }
 }
@@ -258,8 +244,8 @@ enlargeStablePtrTable(void)
   if (SPT_size == 0) {
     // 1st time
     SPT_size = INIT_SPT_SIZE;
-    stable_ptr_table = stgMallocWords(SPT_size * sizeof(snEntry), 
-                                     "initStablePtrTable");
+    stable_ptr_table = stgMallocBytes(SPT_size * sizeof(snEntry), 
+                                     "enlargeStablePtrTable");
     
     /* we don't use index 0 in the stable name table, because that
      * would conflict with the hash table lookup operations which
@@ -272,9 +258,10 @@ enlargeStablePtrTable(void)
     // 2nd and subsequent times
     SPT_size *= 2;
     stable_ptr_table = 
-      stgReallocWords(stable_ptr_table, SPT_size * sizeof(snEntry),
+      stgReallocBytes(stable_ptr_table, 
+                     SPT_size * sizeof(snEntry),
                      "enlargeStablePtrTable");
-    
+
     initFreeList(stable_ptr_table + old_SPT_size, old_SPT_size, NULL);
   }
 }
@@ -392,7 +379,7 @@ gcStablePtrTable( void )
                    continue;
                    
                } else {
-                   (StgClosure *)p->addr = isAlive((StgClosure *)p->addr);
+                 p->addr = (StgPtr)isAlive((StgClosure *)p->addr);
                    IF_DEBUG(stable, fprintf(stderr,"Stable name %d still alive at %p, ref %d\n", p - stable_ptr_table, p->addr, p->ref));
                }
            }