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/*-----------------------------------------------------------------*-C-*---
* File: handc/runtime/finalize.c
*
* Copyright (C)1997 Donovan Kolbly <d.kolbly@rscheme.org>
* as part of the RScheme project, licensed for free use.
* See <http://www.rscheme.org/> for the latest information.
*
* File version: 1.6
* File mod date: 1997.11.29 23:10:50
* System build: v0.7.2, 97.12.21
*
* Purpose: Support for finalization and weak pointers
*------------------------------------------------------------------------*
* Notes:
* This support is GC-independent, supplying the client (language)
* side definitions for `safe_for_object_is_dead' and the internal
* function mark_as_finalizable and found_weak_slot
*------------------------------------------------------------------------*/
#include <stdlib.h>
#include <rscheme/intrs.h>
#include <rscheme/osglue.h>
#include <rscheme/gcserver.h>
#include <rscheme/smemory.h>
#include <rscheme/scheme.h>
struct obj_list {
obj *contents;
unsigned count;
unsigned capacity;
};
static struct obj_list fzable = { NULL, 0, 0 };
static struct obj_list wkslot = { NULL, 0, 0 };
void shrink_list( struct obj_list *lst )
{
}
void add_to_list( struct obj_list *lst, obj item )
{
if (lst->count >= lst->capacity)
{
if (lst->count == 0)
{
lst->capacity = 16;
lst->contents = (obj *)malloc( sizeof( obj ) * 16 );
}
else
{
lst->capacity *= 2;
lst->contents = (obj *)realloc( lst->contents,
sizeof( obj ) * lst->capacity );
}
}
lst->contents[lst->count++] = item;
}
void mark_as_finalizable( obj item )
{
add_to_list( &fzable, item );
}
/* returns YES if the GC can flip now. If this function returns YES,
* the GC _will_ flip (we send the GC_FLIP signal to the scheme system)
*/
rs_bool gc_cycle_finish_ok( void )
{
unsigned i;
obj fzing_list = NIL_OBJ;
unsigned fzing_cnt = 0;
for (i=0; i<fzable.count;)
{
if (is_object_dead( PTR_TO_GCPTR(fzable.contents[i])) )
{
fzing_list = cons( fzable.contents[i], fzing_list );
fzable.contents[i] = fzable.contents[--fzable.count];
fzing_cnt++;
}
else
i++;
}
if (!EQ(fzing_list,NIL_OBJ))
{
/* signal the scheme system */
struct RSSIG_info sig;
sig.signum = RSSIG_FINALIZE;
sig.data.finalize.finalize_list = fzing_list;
sig.data.finalize.count = fzing_cnt;
os_enqueue_sig( &sig );
return NO;
}
else
{
/* send the `gc flipped' signal */
struct RSSIG_info sig;
sig.signum = RSSIG_GC_FLIP;
os_enqueue_sig( &sig );
/* nil out weak pointers */
if (wkslot.count < (wkslot.capacity / 2))
shrink_list( &wkslot );
for (i=0; i<wkslot.count; i++)
{
obj *vp, v;
vp = (obj *)OBJ_TO_RAW_PTR(wkslot.contents[i]);
v = *vp;
if (OBJ_ISA_PTR(v) && is_object_dead(PTR_TO_GCPTR(v)))
{
*vp = FALSE_OBJ;
}
}
wkslot.count = 0;
return YES;
}
}
void found_weak_slot( obj in, obj *slot )
{
add_to_list( &wkslot, RAW_PTR_TO_OBJ(slot) );
}
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