#define lgc_c
#define LUA_CORE
#include "lprefix.h"
#include <string.h>
#include "lua.h"
#include "ldebug.h"
#include "ldo.h"
#include "lfunc.h"
#include "lgc.h"
#include "lmem.h"
#include "lobject.h"
#include "lstate.h"
#include "lstring.h"
#include "ltable.h"
#include "ltm.h"
#define GCSinsideatomic (GCSpause + 1)
#define GCSWEEPCOST ((sizeof(TString) + 4) / 4)
#define GCSWEEPMAX (cast_int((GCSTEPSIZE / GCSWEEPCOST) / 4))
#define GCFINALIZECOST GCSWEEPCOST
#define STEPMULADJ 200
#define PAUSEADJ 100
#define maskcolors (~(bitmask(BLACKBIT) | WHITEBITS))
#define makewhite(g,x) \
(x->marked = cast_byte((x->marked & maskcolors) | luaC_white(g)))
#define white2gray(x) resetbits(x->marked, WHITEBITS)
#define black2gray(x) resetbit(x->marked, BLACKBIT)
#define valiswhite(x) (iscollectable(x) && iswhite(gcvalue(x)))
#define checkdeadkey(n) lua_assert(!ttisdeadkey(gkey(n)) || ttisnil(gval(n)))
#define checkconsistency(obj) \
lua_longassert(!iscollectable(obj) || righttt(obj))
#define markvalue(g,o) { checkconsistency(o); \
if (valiswhite(o)) reallymarkobject(g,gcvalue(o)); }
#define markobject(g,t) { if (iswhite(t)) reallymarkobject(g, obj2gco(t)); }
#define markobjectN(g,t) { if (t) markobject(g,t); }
static void reallymarkobject (global_State *g, GCObject *o);
#define gnodelast(h) gnode(h, cast(size_t, sizenode(h)))
#define linkgclist(o,p) ((o)->gclist = (p), (p) = obj2gco(o))
static void removeentry (Node *n) {
lua_assert(ttisnil(gval(n)));
if (valiswhite(gkey(n)))
setdeadvalue(wgkey(n));
}
static int iscleared (global_State *g, const TValue *o) {
if (!iscollectable(o)) return 0;
else if (ttisstring(o)) {
markobject(g, tsvalue(o));
return 0;
}
else return iswhite(gcvalue(o));
}
void luaC_barrier_ (lua_State *L, GCObject *o, GCObject *v) {
global_State *g = G(L);
lua_assert(isblack(o) && iswhite(v) && !isdead(g, v) && !isdead(g, o));
if (keepinvariant(g))
reallymarkobject(g, v);
else {
lua_assert(issweepphase(g));
makewhite(g, o);
}
}
void luaC_barrierback_ (lua_State *L, Table *t) {
global_State *g = G(L);
lua_assert(isblack(t) && !isdead(g, t));
black2gray(t);
linkgclist(t, g->grayagain);
}
void luaC_upvalbarrier_ (lua_State *L, UpVal *uv) {
global_State *g = G(L);
GCObject *o = gcvalue(uv->v);
lua_assert(!upisopen(uv));
if (keepinvariant(g))
markobject(g, o);
}
void luaC_fix (lua_State *L, GCObject *o) {
global_State *g = G(L);
lua_assert(g->allgc == o);
white2gray(o);
g->allgc = o->next;
o->next = g->fixedgc;
g->fixedgc = o;
}
GCObject *luaC_newobj (lua_State *L, int tt, size_t sz) {
global_State *g = G(L);
GCObject *o = cast(GCObject *, luaM_newobject(L, novariant(tt), sz));
o->marked = luaC_white(g);
o->tt = tt;
o->next = g->allgc;
g->allgc = o;
return o;
}
static void reallymarkobject (global_State *g, GCObject *o) {
reentry:
white2gray(o);
switch (o->tt) {
case LUA_TSHRSTR: {
gray2black(o);
g->GCmemtrav += sizelstring(gco2ts(o)->shrlen);
break;
}
case LUA_TLNGSTR: {
gray2black(o);
g->GCmemtrav += sizelstring(gco2ts(o)->u.lnglen);
break;
}
case LUA_TUSERDATA: {
TValue uvalue;
markobjectN(g, gco2u(o)->metatable);
gray2black(o);
g->GCmemtrav += sizeudata(gco2u(o));
getuservalue(g->mainthread, gco2u(o), &uvalue);
if (valiswhite(&uvalue)) {
o = gcvalue(&uvalue);
goto reentry;
}
break;
}
case LUA_TLCL: {
linkgclist(gco2lcl(o), g->gray);
break;
}
case LUA_TCCL: {
linkgclist(gco2ccl(o), g->gray);
break;
}
case LUA_TTABLE: {
linkgclist(gco2t(o), g->gray);
break;
}
case LUA_TTHREAD: {
linkgclist(gco2th(o), g->gray);
break;
}
case LUA_TPROTO: {
linkgclist(gco2p(o), g->gray);
break;
}
default: lua_assert(0); break;
}
}
static void markmt (global_State *g) {
int i;
for (i=0; i < LUA_NUMTAGS; i++)
markobjectN(g, g->mt[i]);
}
static void markbeingfnz (global_State *g) {
GCObject *o;
for (o = g->tobefnz; o != NULL; o = o->next)
markobject(g, o);
}
static void remarkupvals (global_State *g) {
lua_State *thread;
lua_State **p = &g->twups;
while ((thread = *p) != NULL) {
lua_assert(!isblack(thread));
if (isgray(thread) && thread->openupval != NULL)
p = &thread->twups;
else {
UpVal *uv;
*p = thread->twups;
thread->twups = thread;
for (uv = thread->openupval; uv != NULL; uv = uv->u.open.next) {
if (uv->u.open.touched) {
markvalue(g, uv->v);
uv->u.open.touched = 0;
}
}
}
}
}
static void restartcollection (global_State *g) {
g->gray = g->grayagain = NULL;
g->weak = g->allweak = g->ephemeron = NULL;
markobject(g, g->mainthread);
markvalue(g, &g->l_registry);
markmt(g);
markbeingfnz(g);
}
static void traverseweakvalue (global_State *g, Table *h) {
Node *n, *limit = gnodelast(h);
int hasclears = (h->sizearray > 0);
for (n = gnode(h, 0); n < limit; n++) {
checkdeadkey(n);
if (ttisnil(gval(n)))
removeentry(n);
else {
lua_assert(!ttisnil(gkey(n)));
markvalue(g, gkey(n));
if (!hasclears && iscleared(g, gval(n)))
hasclears = 1;
}
}
if (g->gcstate == GCSpropagate)
linkgclist(h, g->grayagain);
else if (hasclears)
linkgclist(h, g->weak);
}
static int traverseephemeron (global_State *g, Table *h) {
int marked = 0;
int hasclears = 0;
int hasww = 0;
Node *n, *limit = gnodelast(h);
unsigned int i;
for (i = 0; i < h->sizearray; i++) {
if (valiswhite(&h->array[i])) {
marked = 1;
reallymarkobject(g, gcvalue(&h->array[i]));
}
}
for (n = gnode(h, 0); n < limit; n++) {
checkdeadkey(n);
if (ttisnil(gval(n)))
removeentry(n);
else if (iscleared(g, gkey(n))) {
hasclears = 1;
if (valiswhite(gval(n)))
hasww = 1;
}
else if (valiswhite(gval(n))) {
marked = 1;
reallymarkobject(g, gcvalue(gval(n)));
}
}
if (g->gcstate == GCSpropagate)
linkgclist(h, g->grayagain);
else if (hasww)
linkgclist(h, g->ephemeron);
else if (hasclears)
linkgclist(h, g->allweak);
return marked;
}
static void traversestrongtable (global_State *g, Table *h) {
Node *n, *limit = gnodelast(h);
unsigned int i;
for (i = 0; i < h->sizearray; i++)
markvalue(g, &h->array[i]);
for (n = gnode(h, 0); n < limit; n++) {
checkdeadkey(n);
if (ttisnil(gval(n)))
removeentry(n);
else {
lua_assert(!ttisnil(gkey(n)));
markvalue(g, gkey(n));
markvalue(g, gval(n));
}
}
}
static lu_mem traversetable (global_State *g, Table *h) {
const char *weakkey, *weakvalue;
const TValue *mode = gfasttm(g, h->metatable, TM_MODE);
markobjectN(g, h->metatable);
if (mode && ttisstring(mode) &&
((weakkey = strchr(svalue(mode), 'k')),
(weakvalue = strchr(svalue(mode), 'v')),
(weakkey || weakvalue))) {
black2gray(h);
if (!weakkey)
traverseweakvalue(g, h);
else if (!weakvalue)
traverseephemeron(g, h);
else
linkgclist(h, g->allweak);
}
else
traversestrongtable(g, h);
return sizeof(Table) + sizeof(TValue) * h->sizearray +
sizeof(Node) * cast(size_t, sizenode(h));
}
static int traverseproto (global_State *g, Proto *f) {
int i;
if (f->cache && iswhite(f->cache))
f->cache = NULL;
markobjectN(g, f->source);
for (i = 0; i < f->sizek; i++)
markvalue(g, &f->k[i]);
for (i = 0; i < f->sizeupvalues; i++)
markobjectN(g, f->upvalues[i].name);
for (i = 0; i < f->sizep; i++)
markobjectN(g, f->p[i]);
for (i = 0; i < f->sizelocvars; i++)
markobjectN(g, f->locvars[i].varname);
return sizeof(Proto) + sizeof(Instruction) * f->sizecode +
sizeof(Proto *) * f->sizep +
sizeof(TValue) * f->sizek +
sizeof(int) * f->sizelineinfo +
sizeof(LocVar) * f->sizelocvars +
sizeof(Upvaldesc) * f->sizeupvalues;
}
static lu_mem traverseCclosure (global_State *g, CClosure *cl) {
int i;
for (i = 0; i < cl->nupvalues; i++)
markvalue(g, &cl->upvalue[i]);
return sizeCclosure(cl->nupvalues);
}
static lu_mem traverseLclosure (global_State *g, LClosure *cl) {
int i;
markobjectN(g, cl->p);
for (i = 0; i < cl->nupvalues; i++) {
UpVal *uv = cl->upvals[i];
if (uv != NULL) {
if (upisopen(uv) && g->gcstate != GCSinsideatomic)
uv->u.open.touched = 1;
else
markvalue(g, uv->v);
}
}
return sizeLclosure(cl->nupvalues);
}
static lu_mem traversethread (global_State *g, lua_State *th) {
StkId o = th->stack;
if (o == NULL)
return 1;
lua_assert(g->gcstate == GCSinsideatomic ||
th->openupval == NULL || isintwups(th));
for (; o < th->top; o++)
markvalue(g, o);
if (g->gcstate == GCSinsideatomic) {
StkId lim = th->stack + th->stacksize;
for (; o < lim; o++)
setnilvalue(o);
if (!isintwups(th) && th->openupval != NULL) {
th->twups = g->twups;
g->twups = th;
}
}
else if (g->gckind != KGC_EMERGENCY)
luaD_shrinkstack(th);
return (sizeof(lua_State) + sizeof(TValue) * th->stacksize);
}
static void propagatemark (global_State *g) {
lu_mem size;
GCObject *o = g->gray;
lua_assert(isgray(o));
gray2black(o);
switch (o->tt) {
case LUA_TTABLE: {
Table *h = gco2t(o);
g->gray = h->gclist;
size = traversetable(g, h);
break;
}
case LUA_TLCL: {
LClosure *cl = gco2lcl(o);
g->gray = cl->gclist;
size = traverseLclosure(g, cl);
break;
}
case LUA_TCCL: {
CClosure *cl = gco2ccl(o);
g->gray = cl->gclist;
size = traverseCclosure(g, cl);
break;
}
case LUA_TTHREAD: {
lua_State *th = gco2th(o);
g->gray = th->gclist;
linkgclist(th, g->grayagain);
black2gray(o);
size = traversethread(g, th);
break;
}
case LUA_TPROTO: {
Proto *p = gco2p(o);
g->gray = p->gclist;
size = traverseproto(g, p);
break;
}
default: lua_assert(0); return;
}
g->GCmemtrav += size;
}
static void propagateall (global_State *g) {
while (g->gray) propagatemark(g);
}
static void convergeephemerons (global_State *g) {
int changed;
do {
GCObject *w;
GCObject *next = g->ephemeron;
g->ephemeron = NULL;
changed = 0;
while ((w = next) != NULL) {
next = gco2t(w)->gclist;
if (traverseephemeron(g, gco2t(w))) {
propagateall(g);
changed = 1;
}
}
} while (changed);
}
static void clearkeys (global_State *g, GCObject *l, GCObject *f) {
for (; l != f; l = gco2t(l)->gclist) {
Table *h = gco2t(l);
Node *n, *limit = gnodelast(h);
for (n = gnode(h, 0); n < limit; n++) {
if (!ttisnil(gval(n)) && (iscleared(g, gkey(n)))) {
setnilvalue(gval(n));
removeentry(n);
}
}
}
}
static void clearvalues (global_State *g, GCObject *l, GCObject *f) {
for (; l != f; l = gco2t(l)->gclist) {
Table *h = gco2t(l);
Node *n, *limit = gnodelast(h);
unsigned int i;
for (i = 0; i < h->sizearray; i++) {
TValue *o = &h->array[i];
if (iscleared(g, o))
setnilvalue(o);
}
for (n = gnode(h, 0); n < limit; n++) {
if (!ttisnil(gval(n)) && iscleared(g, gval(n))) {
setnilvalue(gval(n));
removeentry(n);
}
}
}
}
void luaC_upvdeccount (lua_State *L, UpVal *uv) {
lua_assert(uv->refcount > 0);
uv->refcount--;
if (uv->refcount == 0 && !upisopen(uv))
luaM_free(L, uv);
}
static void freeLclosure (lua_State *L, LClosure *cl) {
int i;
for (i = 0; i < cl->nupvalues; i++) {
UpVal *uv = cl->upvals[i];
if (uv)
luaC_upvdeccount(L, uv);
}
luaM_freemem(L, cl, sizeLclosure(cl->nupvalues));
}
static void freeobj (lua_State *L, GCObject *o) {
switch (o->tt) {
case LUA_TPROTO: luaF_freeproto(L, gco2p(o)); break;
case LUA_TLCL: {
freeLclosure(L, gco2lcl(o));
break;
}
case LUA_TCCL: {
luaM_freemem(L, o, sizeCclosure(gco2ccl(o)->nupvalues));
break;
}
case LUA_TTABLE: luaH_free(L, gco2t(o)); break;
case LUA_TTHREAD: luaE_freethread(L, gco2th(o)); break;
case LUA_TUSERDATA: luaM_freemem(L, o, sizeudata(gco2u(o))); break;
case LUA_TSHRSTR:
luaS_remove(L, gco2ts(o));
luaM_freemem(L, o, sizelstring(gco2ts(o)->shrlen));
break;
case LUA_TLNGSTR: {
luaM_freemem(L, o, sizelstring(gco2ts(o)->u.lnglen));
break;
}
default: lua_assert(0);
}
}
#define sweepwholelist(L,p) sweeplist(L,p,MAX_LUMEM)
static GCObject **sweeplist (lua_State *L, GCObject **p, lu_mem count);
static GCObject **sweeplist (lua_State *L, GCObject **p, lu_mem count) {
global_State *g = G(L);
int ow = otherwhite(g);
int white = luaC_white(g);
while (*p != NULL && count-- > 0) {
GCObject *curr = *p;
int marked = curr->marked;
if (isdeadm(ow, marked)) {
*p = curr->next;
freeobj(L, curr);
}
else {
curr->marked = cast_byte((marked & maskcolors) | white);
p = &curr->next;
}
}
return (*p == NULL) ? NULL : p;
}
static GCObject **sweeptolive (lua_State *L, GCObject **p, int *n) {
GCObject **old = p;
int i = 0;
do {
i++;
p = sweeplist(L, p, 1);
} while (p == old);
if (n) *n += i;
return p;
}
static void checkSizes (lua_State *L, global_State *g) {
if (g->gckind != KGC_EMERGENCY) {
l_mem olddebt = g->GCdebt;
luaZ_freebuffer(L, &g->buff);
if (g->strt.nuse < g->strt.size / 4)
luaS_resize(L, g->strt.size / 2);
g->GCestimate += g->GCdebt - olddebt;
}
}
static GCObject *udata2finalize (global_State *g) {
GCObject *o = g->tobefnz;
lua_assert(tofinalize(o));
g->tobefnz = o->next;
o->next = g->allgc;
g->allgc = o;
resetbit(o->marked, FINALIZEDBIT);
if (issweepphase(g))
makewhite(g, o);
return o;
}
static void dothecall (lua_State *L, void *ud) {
UNUSED(ud);
luaD_call(L, L->top - 2, 0, 0);
}
static void GCTM (lua_State *L, int propagateerrors) {
global_State *g = G(L);
const TValue *tm;
TValue v;
setgcovalue(L, &v, udata2finalize(g));
tm = luaT_gettmbyobj(L, &v, TM_GC);
if (tm != NULL && ttisfunction(tm)) {
int status;
lu_byte oldah = L->allowhook;
int running = g->gcrunning;
L->allowhook = 0;
g->gcrunning = 0;
setobj2s(L, L->top, tm);
setobj2s(L, L->top + 1, &v);
L->top += 2;
status = luaD_pcall(L, dothecall, NULL, savestack(L, L->top - 2), 0);
L->allowhook = oldah;
g->gcrunning = running;
if (status != LUA_OK && propagateerrors) {
if (status == LUA_ERRRUN) {
const char *msg = (ttisstring(L->top - 1))
? svalue(L->top - 1)
: "no message";
luaO_pushfstring(L, "error in __gc metamethod (%s)", msg);
status = LUA_ERRGCMM;
}
luaD_throw(L, status);
}
}
}
static int runafewfinalizers (lua_State *L) {
global_State *g = G(L);
unsigned int i;
lua_assert(!g->tobefnz || g->gcfinnum > 0);
for (i = 0; g->tobefnz && i < g->gcfinnum; i++)
GCTM(L, 1);
g->gcfinnum = (!g->tobefnz) ? 0
: g->gcfinnum * 2;
return i;
}
static void callallpendingfinalizers (lua_State *L, int propagateerrors) {
global_State *g = G(L);
while (g->tobefnz)
GCTM(L, propagateerrors);
}
static GCObject **findlast (GCObject **p) {
while (*p != NULL)
p = &(*p)->next;
return p;
}
static void separatetobefnz (global_State *g, int all) {
GCObject *curr;
GCObject **p = &g->finobj;
GCObject **lastnext = findlast(&g->tobefnz);
while ((curr = *p) != NULL) {
lua_assert(tofinalize(curr));
if (!(iswhite(curr) || all))
p = &curr->next;
else {
*p = curr->next;
curr->next = *lastnext;
*lastnext = curr;
lastnext = &curr->next;
}
}
}
void luaC_checkfinalizer (lua_State *L, GCObject *o, Table *mt) {
global_State *g = G(L);
if (tofinalize(o) ||
gfasttm(g, mt, TM_GC) == NULL)
return;
else {
GCObject **p;
if (issweepphase(g)) {
makewhite(g, o);
if (g->sweepgc == &o->next)
g->sweepgc = sweeptolive(L, g->sweepgc, NULL);
}
for (p = &g->allgc; *p != o; p = &(*p)->next) { }
*p = o->next;
o->next = g->finobj;
g->finobj = o;
l_setbit(o->marked, FINALIZEDBIT);
}
}
static void setpause (global_State *g) {
l_mem threshold, debt;
l_mem estimate = g->GCestimate / PAUSEADJ;
lua_assert(estimate > 0);
threshold = (g->gcpause < MAX_LMEM / estimate)
? estimate * g->gcpause
: MAX_LMEM;
debt = gettotalbytes(g) - threshold;
luaE_setdebt(g, debt);
}
static int entersweep (lua_State *L) {
global_State *g = G(L);
int n = 0;
g->gcstate = GCSswpallgc;
lua_assert(g->sweepgc == NULL);
g->sweepgc = sweeptolive(L, &g->allgc, &n);
return n;
}
void luaC_freeallobjects (lua_State *L) {
global_State *g = G(L);
separatetobefnz(g, 1);
lua_assert(g->finobj == NULL);
callallpendingfinalizers(L, 0);
lua_assert(g->tobefnz == NULL);
g->currentwhite = WHITEBITS;
g->gckind = KGC_NORMAL;
sweepwholelist(L, &g->finobj);
sweepwholelist(L, &g->allgc);
sweepwholelist(L, &g->fixedgc);
lua_assert(g->strt.nuse == 0);
}
static l_mem atomic (lua_State *L) {
global_State *g = G(L);
l_mem work;
GCObject *origweak, *origall;
GCObject *grayagain = g->grayagain;
lua_assert(g->ephemeron == NULL && g->weak == NULL);
lua_assert(!iswhite(g->mainthread));
g->gcstate = GCSinsideatomic;
g->GCmemtrav = 0;
markobject(g, L);
markvalue(g, &g->l_registry);
markmt(g);
remarkupvals(g);
propagateall(g);
work = g->GCmemtrav;
g->gray = grayagain;
propagateall(g);
g->GCmemtrav = 0;
convergeephemerons(g);
clearvalues(g, g->weak, NULL);
clearvalues(g, g->allweak, NULL);
origweak = g->weak; origall = g->allweak;
work += g->GCmemtrav;
separatetobefnz(g, 0);
g->gcfinnum = 1;
markbeingfnz(g);
propagateall(g);
g->GCmemtrav = 0;
convergeephemerons(g);
clearkeys(g, g->ephemeron, NULL);
clearkeys(g, g->allweak, NULL);
clearvalues(g, g->weak, origweak);
clearvalues(g, g->allweak, origall);
luaS_clearcache(g);
g->currentwhite = cast_byte(otherwhite(g));
work += g->GCmemtrav;
return work;
}
static lu_mem sweepstep (lua_State *L, global_State *g,
int nextstate, GCObject **nextlist) {
if (g->sweepgc) {
l_mem olddebt = g->GCdebt;
g->sweepgc = sweeplist(L, g->sweepgc, GCSWEEPMAX);
g->GCestimate += g->GCdebt - olddebt;
if (g->sweepgc)
return (GCSWEEPMAX * GCSWEEPCOST);
}
g->gcstate = nextstate;
g->sweepgc = nextlist;
return 0;
}
static lu_mem singlestep (lua_State *L) {
global_State *g = G(L);
switch (g->gcstate) {
case GCSpause: {
g->GCmemtrav = g->strt.size * sizeof(GCObject*);
restartcollection(g);
g->gcstate = GCSpropagate;
return g->GCmemtrav;
}
case GCSpropagate: {
g->GCmemtrav = 0;
lua_assert(g->gray);
propagatemark(g);
if (g->gray == NULL)
g->gcstate = GCSatomic;
return g->GCmemtrav;
}
case GCSatomic: {
lu_mem work;
int sw;
propagateall(g);
work = atomic(L);
sw = entersweep(L);
g->GCestimate = gettotalbytes(g); ;
return work + sw * GCSWEEPCOST;
}
case GCSswpallgc: {
return sweepstep(L, g, GCSswpfinobj, &g->finobj);
}
case GCSswpfinobj: {
return sweepstep(L, g, GCSswptobefnz, &g->tobefnz);
}
case GCSswptobefnz: {
return sweepstep(L, g, GCSswpend, NULL);
}
case GCSswpend: {
makewhite(g, g->mainthread);
checkSizes(L, g);
g->gcstate = GCScallfin;
return 0;
}
case GCScallfin: {
if (g->tobefnz && g->gckind != KGC_EMERGENCY) {
int n = runafewfinalizers(L);
return (n * GCFINALIZECOST);
}
else {
g->gcstate = GCSpause;
return 0;
}
}
default: lua_assert(0); return 0;
}
}
void luaC_runtilstate (lua_State *L, int statesmask) {
global_State *g = G(L);
while (!testbit(statesmask, g->gcstate))
singlestep(L);
}
static l_mem getdebt (global_State *g) {
l_mem debt = g->GCdebt;
int stepmul = g->gcstepmul;
debt = (debt / STEPMULADJ) + 1;
debt = (debt < MAX_LMEM / stepmul) ? debt * stepmul : MAX_LMEM;
return debt;
}
void luaC_step (lua_State *L) {
global_State *g = G(L);
l_mem debt = getdebt(g);
if (!g->gcrunning) {
luaE_setdebt(g, -GCSTEPSIZE * 10);
return;
}
do {
lu_mem work = singlestep(L);
debt -= work;
} while (debt > -GCSTEPSIZE && g->gcstate != GCSpause);
if (g->gcstate == GCSpause)
setpause(g);
else {
debt = (debt / g->gcstepmul) * STEPMULADJ;
luaE_setdebt(g, debt);
runafewfinalizers(L);
}
}
void luaC_fullgc (lua_State *L, int isemergency) {
global_State *g = G(L);
lua_assert(g->gckind == KGC_NORMAL);
if (isemergency) g->gckind = KGC_EMERGENCY;
if (keepinvariant(g)) {
entersweep(L);
}
luaC_runtilstate(L, bitmask(GCSpause));
luaC_runtilstate(L, ~bitmask(GCSpause));
luaC_runtilstate(L, bitmask(GCScallfin));
lua_assert(g->GCestimate == gettotalbytes(g));
luaC_runtilstate(L, bitmask(GCSpause));
g->gckind = KGC_NORMAL;
setpause(g);
}