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#include "gc.h"
#include "exc.h"
#include "consts.h"
#include <vector>
#if defined(GC_DEBUG) || defined (GC_INFO)
#include <cstdio>
typedef unsigned long long ull;
#endif
static EvalObj *gcq[GC_QUEUE_SIZE];
static Container *cyc_list[GC_QUEUE_SIZE];
GarbageCollector::GarbageCollector() {
mapping.clear();
pending_list = NULL;
resolve_threshold = GC_CYC_THRESHOLD;
}
GarbageCollector::PendingEntry::PendingEntry(
EvalObj *_obj, PendingEntry *_next) : obj(_obj), next(_next) {}
void GarbageCollector::expose(EvalObj *ptr) {
bool flag = mapping.count(ptr);
if (flag)
{
#ifdef GC_DEBUG
fprintf(stderr, "GC: 0x%llx exposed. count = %lu \"%s\"\n",
(ull)ptr, mapping[ptr] - 1, ptr->ext_repr().c_str());
#endif
if (!--mapping[ptr])
{
#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;
if (mapping.count(p->obj) && mapping[p->obj] == 0)
*r++ = p->obj;
delete p;
} // fetch the pending pointers in the list
// clear the list
pending_list = NULL;
/* for (EvalObj2Int::iterator it = mapping.begin();
it != mapping.end(); it++)
if (it->second == 0) *r++ = it->first;*/
#ifdef GC_INFO
fprintf(stderr, "%ld\n", mapping.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;
mapping.erase(*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, mapping.size());
#endif
#ifdef GC_DEBUG
/* for (EvalObj2Int::iterator it = mapping.begin();
it != mapping.end(); it++)
fprintf(stderr, "%llx => %s\n", (ull)it->first, it->first->ext_repr().c_str());
*/
#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;
#ifdef GC_DEBUG
fprintf(stderr, "GC: 0x%llx attached. count = %lu \"%s\"\n",
(ull)ptr, mapping[ptr], ptr->ext_repr().c_str());
#endif
if (mapping.size() > GC_QUEUE_SIZE >> 1)
force();
return ptr; // passing through
}
void GarbageCollector::cycle_resolve() {
if (mapping.size() < resolve_threshold)
return;
EvalObjSet visited;
Container **clptr = cyc_list;
for (EvalObj2Int::iterator it = mapping.begin();
it != mapping.end(); it++)
if (it->first->is_container())
{
Container *p = static_cast<Container*>(it->first);
(*clptr++ = p)->gc_refs = it->second; // 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)
{
*r++ = *p;
visited.insert(*p);
}
for (; l != r; l++)
{
Container *p = static_cast<Container*>(*l);
p->keep = true;
p->gc_trigger(r, visited);
}
for (Container **p = cyc_list; p < clptr; p++)
if (!(*p)->keep)
{
delete *p;
mapping.erase(*p);
}
#ifdef GC_INFO
fprintf(stderr, "GC: cycle resolved.\n");
#endif
}
void GarbageCollector::collect() {
force();
if (mapping.size() < resolve_threshold)
return;
cycle_resolve();
force();
}
size_t GarbageCollector::get_remaining() {
return mapping.size();
}
void GarbageCollector::set_resolve_threshold(size_t new_thres) {
resolve_threshold = new_thres;
}
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