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#include "gc.h"
#include "exc.h"
#include "consts.h"
#include <vector>
#include <cstdio>
#if defined(GC_DEBUG) || defined (GC_INFO)
typedef unsigned long long ull;
#endif
static EvalObj *gcq[GC_QUEUE_SIZE];
static Container *cyc_list[GC_QUEUE_SIZE];
ObjEntry *oe_null;
GarbageCollector::GarbageCollector() {
joined = new ObjEntry(NULL, NULL);
joined->next = oe_null = new ObjEntry(NULL, NULL);
joined_size = 0;
pending_list = NULL;
resolve_threshold = GC_CYC_THRESHOLD;
}
GarbageCollector::PendingEntry::PendingEntry(
EvalObj *_obj, PendingEntry *_next) : obj(_obj), next(_next) {}
void GarbageCollector::expose(EvalObj *ptr) {
if (ptr == NULL || ptr->gc_rec == NULL) return;
#ifdef GC_DEBUG
fprintf(stderr, "GC: 0x%llx exposed. count = %lu \"%s\"\n",
(ull)ptr, ptr->gc_rec->gc_cnt - 1, ptr->ext_repr().c_str());
#endif
if (--ptr->gc_rec->gc_cnt == 0)
{
#ifdef GC_DEBUG
fprintf(stderr, "GC: 0x%llx pending. \n", (ull)ptr);
#endif
pending_list = new PendingEntry(ptr, pending_list);
}
}
void GarbageCollector::force() {
EvalObj **l = gcq, **r = l;
for (PendingEntry *p = pending_list, *np; p; p = np)
{
np = p->next;
EvalObj *obj = p->obj;
if (obj->gc_rec && !obj->gc_rec->gc_cnt)
*r++ = obj;
delete p;
} // fetch the pending pointers in the list
// clear the list
pending_list = NULL;
#ifdef GC_INFO
fprintf(stderr, "%ld\n", joined_size);
size_t cnt = 0;
#endif
#ifdef GC_DEBUG
fprintf(stderr,
"================================\n"
"GC: Forcing the clear process...\n");
#endif
for (; l != r; l++)
{
#ifdef GC_DEBUG
fprintf(stderr, "GC: !!! destroying space 0x%llx: %s. \n",
(ull)*l, (*l)->ext_repr().c_str());
#endif
#ifdef GC_INFO
cnt++;
#endif
delete *l;
// maybe it's a complex structure,
// so that more pointers are reported
for (PendingEntry *p = pending_list, *np; p; p = np)
{
np = p->next;
*r++ = p->obj;
if (r == gcq + GC_QUEUE_SIZE)
throw NormalError(RUN_ERR_GC_OVERFLOW);
delete p;
}
pending_list = NULL;
}
#ifdef GC_INFO
fprintf(stderr, "GC: Forced clear, %lu objects are freed, "
"%lu remains\n"
"=============================\n", cnt, joined_size);
#endif
#ifdef GC_DEBUG
#endif
}
EvalObj *GarbageCollector::attach(EvalObj *ptr) {
if (!ptr) return NULL; // NULL pointer
/* bool flag = mapping.count(ptr);
if (flag) mapping[ptr]++;
else mapping[ptr] = 1;
*/
ptr->gc_rec->gc_cnt++;
#ifdef GC_DEBUG
fprintf(stderr, "GC: 0x%llx attached. count = %lu \"%s\"\n",
(ull)ptr, ptr->gc_rec->gc_cnt, ptr->ext_repr().c_str());
#endif
/* if (mapping.size() > GC_QUEUE_SIZE >> 1)
force();*/
return ptr; // passing through
}
void GarbageCollector::cycle_resolve() {
Container **clptr = cyc_list;
for (ObjEntry *i = joined->next; i != oe_null; i = i->next)
{
EvalObj *obj = i->obj;
if (obj->is_container())
{
Container *p = static_cast<Container*>(obj);
(*clptr++ = p)->gc_refs = i->gc_cnt; // init the count
p->keep = false;
}
}
EvalObj **l = gcq, **r = l;
for (Container **p = cyc_list; p < clptr; p++)
(*p)->gc_decrement();
for (Container **p = cyc_list; p < clptr; p++)
if ((*p)->gc_refs) // must not be recycled
*r++ = *p;
for (; l != r; l++)
{
Container *p = static_cast<Container*>(*l);
p->keep = true;
p->gc_trigger(r);
}
for (Container **p = cyc_list; p < clptr; p++)
if (!(*p)->keep)
{
delete *p;
}
#ifdef GC_INFO
fprintf(stderr, "GC: cycle resolved.\n");
#endif
}
void GarbageCollector::collect() {
force();
if (joined_size >= resolve_threshold)
{
cycle_resolve();
force();
}
}
size_t GarbageCollector::get_remaining() {
return joined_size;
}
void GarbageCollector::set_resolve_threshold(size_t new_thres) {
resolve_threshold = new_thres;
}
ObjEntry *GarbageCollector::join(EvalObj *ptr) {
ObjEntry *p = new ObjEntry(joined, joined->next);
p->prev->next = p;
p->next->prev = p;
p->gc_cnt = 0;
p->obj = ptr;
joined_size++;
return p;
}
void GarbageCollector::quit(EvalObj *ptr) {
ObjEntry *p = ptr->gc_rec;
p->prev->next = p->next;
p->next->prev = p->prev;
ptr->gc_rec = NULL;
delete p;
joined_size--;
}
ObjEntry::ObjEntry(ObjEntry *_prev, ObjEntry *_next) :
prev(_prev), next(_next) {}
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