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lua/lgc.c
Roberto Ierusalimschy 4a67e48611 new macro 'condmovestack' instead of 'condhardstacktests'
2009-06-08 16:35:59 -03:00

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/*
** $Id: lgc.c,v 2.53 2009/05/21 20:06:11 roberto Exp roberto $
** Garbage Collector
** See Copyright Notice in lua.h
*/
#include <string.h>
#define lgc_c
#define LUA_CORE
#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 GCSTEPSIZE 1024u
#define GCSWEEPMAX 40
#define GCSWEEPCOST 10
#define GCFINALIZECOST 100
#define maskcolors cast_byte(~(bitmask(BLACKBIT)|WHITEBITS))
#define makewhite(g,x) \
(gch(x)->marked = cast_byte((gch(x)->marked & maskcolors) | luaC_white(g)))
#define white2gray(x) resetbits(gch(x)->marked, WHITEBITS)
#define black2gray(x) resetbit(gch(x)->marked, BLACKBIT)
#define stringmark(s) resetbits((s)->tsv.marked, WHITEBITS)
#define isfinalized(u) testbit((u)->marked, FINALIZEDBIT)
#define markvalue(g,o) { checkconsistency(o); \
if (valiswhite(o)) reallymarkobject(g,gcvalue(o)); }
#define markobject(g,t) { if ((t) && iswhite(obj2gco(t))) \
reallymarkobject(g, obj2gco(t)); }
#define setthreshold(g) (g->GCthreshold = (g->estimate/100) * g->gcpause)
static void reallymarkobject (global_State *g, GCObject *o);
/*
** {======================================================
** Generic functions
** =======================================================
*/
static void linktable (Table *h, GCObject **p) {
h->gclist = *p;
*p = obj2gco(h);
}
static void removeentry (Node *n) {
lua_assert(ttisnil(gval(n)));
if (iscollectable(gkey(n)))
setttype(gkey(n), LUA_TDEADKEY); /* dead key; remove it */
}
/*
** The next function tells whether a key or value can be cleared from
** a weak table. Non-collectable objects are never removed from weak
** tables. Strings behave as `values', so are never removed too. for
** other objects: if really collected, cannot keep them; for objects
** being finalized, keep them in keys, but not in values
*/
static int iscleared (const TValue *o, int iskey) {
if (!iscollectable(o)) return 0;
if (ttisstring(o)) {
stringmark(rawtsvalue(o)); /* strings are `values', so are never weak */
return 0;
}
return iswhite(gcvalue(o)) ||
(ttisuserdata(o) && (!iskey && isfinalized(uvalue(o))));
}
void luaC_barrierf (lua_State *L, GCObject *o, GCObject *v) {
global_State *g = G(L);
lua_assert(isblack(o) && iswhite(v) && !isdead(g, v) && !isdead(g, o));
lua_assert(g->gcstate != GCSfinalize && g->gcstate != GCSpause);
lua_assert(ttype(gch(o)) != LUA_TTABLE);
/* must keep invariant? */
if (g->gcstate == GCSpropagate)
reallymarkobject(g, v); /* restore invariant */
else /* don't mind */
makewhite(g, o); /* mark as white just to avoid other barriers */
}
void luaC_barrierback (lua_State *L, Table *t) {
global_State *g = G(L);
GCObject *o = obj2gco(t);
lua_assert(isblack(o) && !isdead(g, o));
lua_assert(g->gcstate != GCSfinalize && g->gcstate != GCSpause);
black2gray(o); /* make table gray (again) */
t->gclist = g->grayagain;
g->grayagain = o;
}
void luaC_link (lua_State *L, GCObject *o, lu_byte tt) {
global_State *g = G(L);
gch(o)->marked = luaC_white(g);
gch(o)->tt = tt;
gch(o)->next = g->rootgc;
g->rootgc = o;
}
void luaC_linkupval (lua_State *L, UpVal *uv) {
global_State *g = G(L);
GCObject *o = obj2gco(uv);
gch(o)->next = g->rootgc; /* link upvalue into `rootgc' list */
g->rootgc = o;
if (isgray(o)) {
if (g->gcstate == GCSpropagate) {
gray2black(o); /* closed upvalues need barrier */
luaC_barrier(L, uv, uv->v);
}
else { /* sweep phase: sweep it (turning it into white) */
makewhite(g, o);
lua_assert(g->gcstate != GCSfinalize && g->gcstate != GCSpause);
}
}
}
/* }====================================================== */
/*
** {======================================================
** Mark functions
** =======================================================
*/
static void reallymarkobject (global_State *g, GCObject *o) {
lua_assert(iswhite(o) && !isdead(g, o));
white2gray(o);
switch (gch(o)->tt) {
case LUA_TSTRING: {
return;
}
case LUA_TUSERDATA: {
Table *mt = gco2u(o)->metatable;
gray2black(o); /* udata are never gray */
markobject(g, mt);
markobject(g, gco2u(o)->env);
return;
}
case LUA_TUPVAL: {
UpVal *uv = gco2uv(o);
markvalue(g, uv->v);
if (uv->v == &uv->u.value) /* closed? */
gray2black(o); /* open upvalues are never black */
return;
}
case LUA_TFUNCTION: {
gco2cl(o)->c.gclist = g->gray;
g->gray = o;
break;
}
case LUA_TTABLE: {
linktable(gco2t(o), &g->gray);
break;
}
case LUA_TTHREAD: {
gco2th(o)->gclist = g->gray;
g->gray = o;
break;
}
case LUA_TPROTO: {
gco2p(o)->gclist = g->gray;
g->gray = o;
break;
}
default: lua_assert(0);
}
}
static void markmt (global_State *g) {
int i;
for (i=0; i<NUM_TAGS; i++)
markobject(g, g->mt[i]);
}
static void markbeingfnz (global_State *g) {
GCObject *o;
for (o = g->tobefnz; o != NULL; o = gch(o)->next) {
lua_assert(testbit(gch(o)->marked, SEPARATED));
makewhite(g, o);
reallymarkobject(g, o);
}
}
/* mark root set */
static void markroot (lua_State *L) {
global_State *g = G(L);
g->gray = NULL;
g->grayagain = NULL;
g->weak = g->ephemeron = g->allweak = NULL;
markobject(g, g->mainthread);
/* make global table be traversed before main stack */
markvalue(g, gt(g->mainthread));
markvalue(g, registry(L));
markmt(g);
markbeingfnz(g); /* mark any finalizing object left from previous cycle */
g->gcstate = GCSpropagate;
}
static void remarkupvals (global_State *g) {
UpVal *uv;
for (uv = g->uvhead.u.l.next; uv != &g->uvhead; uv = uv->u.l.next) {
lua_assert(uv->u.l.next->u.l.prev == uv && uv->u.l.prev->u.l.next == uv);
if (isgray(obj2gco(uv)))
markvalue(g, uv->v);
}
}
/* }====================================================== */
/*
** {======================================================
** Traverse functions
** =======================================================
*/
static void traverseweakvalue (global_State *g, Table *h) {
int i = sizenode(h);
while (i--) {
Node *n = gnode(h, i);
lua_assert(ttype(gkey(n)) != LUA_TDEADKEY || ttisnil(gval(n)));
if (ttisnil(gval(n)))
removeentry(n); /* remove empty entries */
else {
lua_assert(!ttisnil(gkey(n)));
markvalue(g, gkey(n));
}
}
linktable(h, &g->weak);
}
static int traverseephemeron (global_State *g, Table *h) {
int marked = 0;
int hasclears = 0;
int i = h->sizearray;
while (i--) { /* mark array part (numeric keys are 'strong') */
if (valiswhite(&h->array[i])) {
marked = 1;
reallymarkobject(g, gcvalue(&h->array[i]));
}
}
i = sizenode(h);
while (i--) {
Node *n = gnode(h, i);
lua_assert(ttype(gkey(n)) != LUA_TDEADKEY || ttisnil(gval(n)));
if (ttisnil(gval(n))) /* entry is empty? */
removeentry(n); /* remove it */
else if (valiswhite(gval(n))) {
/* value is not marked yet */
if (iscleared(key2tval(n), 1)) /* key is not marked (yet)? */
hasclears = 1; /* may have to propagate mark from key to value */
else { /* mark value only if key is marked */
marked = 1; /* some mark changed status */
reallymarkobject(g, gcvalue(gval(n)));
}
}
}
if (hasclears)
linktable(h, &g->ephemeron);
else /* nothing to propagate */
linktable(h, &g->weak); /* avoid convergence phase */
return marked;
}
static void traversestrongtable (global_State *g, Table *h) {
int i;
i = h->sizearray;
while (i--)
markvalue(g, &h->array[i]);
i = sizenode(h);
while (i--) {
Node *n = gnode(h, i);
lua_assert(ttype(gkey(n)) != LUA_TDEADKEY || ttisnil(gval(n)));
if (ttisnil(gval(n)))
removeentry(n); /* remove empty entries */
else {
lua_assert(!ttisnil(gkey(n)));
markvalue(g, gkey(n));
markvalue(g, gval(n));
}
}
}
static void traversetable (global_State *g, Table *h) {
const TValue *mode = gfasttm(g, h->metatable, TM_MODE);
markobject(g, h->metatable);
if (mode && ttisstring(mode)) { /* is there a weak mode? */
int weakkey = (strchr(svalue(mode), 'k') != NULL);
int weakvalue = (strchr(svalue(mode), 'v') != NULL);
if (weakkey || weakvalue) { /* is really weak? */
black2gray(obj2gco(h)); /* keep table gray */
if (!weakkey) /* strong keys? */
traverseweakvalue(g, h);
else if (!weakvalue) /* strong values? */
traverseephemeron(g, h);
else
linktable(h, &g->allweak); /* nothing to traverse now */
return;
} /* else go through */
}
traversestrongtable(g, h);
}
/*
** All marks are conditional because a GC may happen while the
** prototype is still being created
*/
static void traverseproto (global_State *g, Proto *f) {
int i;
if (f->source) stringmark(f->source);
for (i=0; i<f->sizek; i++) /* mark literals */
markvalue(g, &f->k[i]);
for (i=0; i<f->sizeupvalues; i++) { /* mark upvalue names */
if (f->upvalues[i])
stringmark(f->upvalues[i]);
}
for (i=0; i<f->sizep; i++) /* mark nested protos */
markobject(g, f->p[i]);
for (i=0; i<f->sizelocvars; i++) { /* mark local-variable names */
if (f->locvars[i].varname)
stringmark(f->locvars[i].varname);
}
}
static void traverseclosure (global_State *g, Closure *cl) {
markobject(g, cl->c.env);
if (cl->c.isC) {
int i;
for (i=0; i<cl->c.nupvalues; i++) /* mark its upvalues */
markvalue(g, &cl->c.upvalue[i]);
}
else {
int i;
lua_assert(cl->l.nupvalues == cl->l.p->nups);
markobject(g, cl->l.p);
for (i=0; i<cl->l.nupvalues; i++) /* mark its upvalues */
markobject(g, cl->l.upvals[i]);
}
}
static void traversestack (global_State *g, lua_State *L) {
StkId o;
if (L->stack == NULL)
return; /* stack not completely built yet */
markvalue(g, gt(L)); /* mark global table */
for (o = L->stack; o < L->top; o++)
markvalue(g, o);
if (g->gcstate == GCSatomic) { /* final traversal? */
for (; o <= L->stack_last; o++) /* clear not-marked stack slice */
setnilvalue(o);
}
}
/*
** traverse one gray object, turning it to black.
** Returns `quantity' traversed.
*/
static l_mem propagatemark (global_State *g) {
GCObject *o = g->gray;
lua_assert(isgray(o));
gray2black(o);
switch (gch(o)->tt) {
case LUA_TTABLE: {
Table *h = gco2t(o);
g->gray = h->gclist;
traversetable(g, h);
return sizeof(Table) + sizeof(TValue) * h->sizearray +
sizeof(Node) * sizenode(h);
}
case LUA_TFUNCTION: {
Closure *cl = gco2cl(o);
g->gray = cl->c.gclist;
traverseclosure(g, cl);
return (cl->c.isC) ? sizeCclosure(cl->c.nupvalues) :
sizeLclosure(cl->l.nupvalues);
}
case LUA_TTHREAD: {
lua_State *th = gco2th(o);
g->gray = th->gclist;
th->gclist = g->grayagain;
g->grayagain = o;
black2gray(o);
traversestack(g, th);
return sizeof(lua_State) + sizeof(TValue) * th->stacksize +
sizeof(CallInfo) * th->nci;
}
case LUA_TPROTO: {
Proto *p = gco2p(o);
g->gray = p->gclist;
traverseproto(g, p);
return sizeof(Proto) + sizeof(Instruction) * p->sizecode +
sizeof(Proto *) * p->sizep +
sizeof(TValue) * p->sizek +
sizeof(int) * p->sizelineinfo +
sizeof(LocVar) * p->sizelocvars +
sizeof(TString *) * p->sizeupvalues;
}
default: lua_assert(0); return 0;
}
}
static size_t propagateall (global_State *g) {
size_t m = 0;
while (g->gray) m += propagatemark(g);
return m;
}
static void traverselistofgrays (global_State *g, GCObject **l) {
lua_assert(g->gray == NULL); /* no grays left */
g->gray = *l; /* now 'l' is new gray list */
*l = NULL;
propagateall(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))) {
changed = 1;
propagateall(g);
}
}
} while (changed);
}
/* }====================================================== */
/*
** {======================================================
** Sweep Functions
** =======================================================
*/
/* clear collected entries from weaktables */
static void cleartable (GCObject *l) {
while (l) {
Table *h = gco2t(l);
int i = h->sizearray;
while (i--) {
TValue *o = &h->array[i];
if (iscleared(o, 0)) /* value was collected? */
setnilvalue(o); /* remove value */
}
i = sizenode(h);
while (i--) {
Node *n = gnode(h, i);
if (!ttisnil(gval(n)) && /* non-empty entry? */
(iscleared(key2tval(n), 1) || iscleared(gval(n), 0))) {
setnilvalue(gval(n)); /* remove value ... */
removeentry(n); /* remove entry from table */
}
}
l = h->gclist;
}
}
static void freeobj (lua_State *L, GCObject *o) {
switch (gch(o)->tt) {
case LUA_TPROTO: luaF_freeproto(L, gco2p(o)); break;
case LUA_TFUNCTION: luaF_freeclosure(L, gco2cl(o)); break;
case LUA_TUPVAL: luaF_freeupval(L, gco2uv(o)); 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_TSTRING: {
G(L)->strt.nuse--;
luaM_freemem(L, o, sizestring(gco2ts(o)));
break;
}
default: lua_assert(0);
}
}
static int stackinuse (lua_State *L) {
CallInfo *ci;
StkId lim = L->top;
for (ci = L->ci; ci != NULL; ci = ci->previous) {
lua_assert(ci->top <= L->stack_last);
if (lim < ci->top) lim = ci->top;
}
return cast_int(lim - L->stack) + 1; /* part of stack in use */
}
#define sweepwholelist(L,p) sweeplist(L,p,MAX_LUMEM)
static GCObject **sweeplist (lua_State *L, GCObject **p, lu_mem count);
static void sweepthread (lua_State *L, lua_State *L1, int alive) {
if (L1->stack == NULL) return; /* stack not completely built yet */
sweepwholelist(L, &L1->openupval); /* sweep open upvalues */
if (L1->nci < LUAI_MAXCALLS) /* not handling stack overflow? */
luaE_freeCI(L1); /* free extra CallInfo slots */
/* should not change the stack during an emergency gc cycle */
if (alive && G(L)->gckind != KGC_EMERGENCY) {
int goodsize = 5 * stackinuse(L1) / 4 + LUA_MINSTACK;
if ((L1->stacksize - EXTRA_STACK) > goodsize)
luaD_reallocstack(L1, goodsize);
else
condmovestack(L1);
}
}
static GCObject **sweeplist (lua_State *L, GCObject **p, lu_mem count) {
GCObject *curr;
global_State *g = G(L);
int deadmask = otherwhite(g);
while ((curr = *p) != NULL && count-- > 0) {
int alive = (gch(curr)->marked ^ WHITEBITS) & deadmask;
if (ttisthread(gch(curr)))
sweepthread(L, gco2th(curr), alive);
if (alive) {
lua_assert(!isdead(g, curr) || testbit(gch(curr)->marked, FIXEDBIT));
makewhite(g, curr); /* make it white (for next cycle) */
p = &gch(curr)->next;
}
else { /* must erase `curr' */
lua_assert(isdead(g, curr) || deadmask == bitmask(SFIXEDBIT));
*p = gch(curr)->next; /* remove 'curr' from list */
freeobj(L, curr);
}
}
return p;
}
/* }====================================================== */
/*
** {======================================================
** Finalization
** =======================================================
*/
static void checkSizes (lua_State *L) {
global_State *g = G(L);
if (g->strt.nuse < cast(lu_int32, g->strt.size)) {
/* size could be the smaller power of 2 larger than 'nuse' */
int size = 1 << luaO_ceillog2(g->strt.nuse);
if (size < g->strt.size) /* current table too large? */
luaS_resize(L, size); /* shrink it */
}
luaZ_freebuffer(L, &g->buff);
}
static Udata *udata2finalize (global_State *g) {
GCObject *o = g->tobefnz; /* get first element */
g->tobefnz = gch(o)->next; /* remove it from 'tobefnz' list */
gch(o)->next = g->rootgc; /* return it to `root' list */
g->rootgc = o;
lua_assert(isfinalized(gch(o)));
resetbit(gch(o)->marked, SEPARATED); /* mark it as such */
makewhite(g, o);
return rawgco2u(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);
Udata *udata = udata2finalize(g);
const TValue *tm = gfasttm(g, udata->uv.metatable, TM_GC);
if (tm != NULL && ttisfunction(tm)) {
int status;
lu_byte oldah = L->allowhook;
lu_mem oldt = g->GCthreshold;
L->allowhook = 0; /* stop debug hooks during GC tag method */
g->GCthreshold = 2*g->totalbytes; /* avoid GC steps */
setobj2s(L, L->top, tm);
setuvalue(L, L->top+1, udata);
L->top += 2;
status = luaD_pcall(L, dothecall, NULL, savestack(L, L->top - 2), 0);
if (status != LUA_OK && propagateerrors) { /* error while running __gc? */
if (status == LUA_ERRRUN) { /* is there an error msg.? */
luaO_pushfstring(L, "error in __gc tag method (%s)",
lua_tostring(L, -1));
status = LUA_ERRGCMM; /* error in __gc metamethod */
}
luaD_throw(L, status); /* re-send error */
}
L->allowhook = oldah; /* restore hooks */
g->GCthreshold = oldt; /* restore threshold */
}
}
/*
** Call all GC tag methods (without raising errors)
*/
void luaC_callAllGCTM (lua_State *L) {
while (G(L)->tobefnz) GCTM(L, 0);
}
/* move 'dead' udata that need finalization to list 'tobefnz' */
size_t luaC_separateudata (lua_State *L, int all) {
global_State *g = G(L);
size_t deadmem = 0; /* total size of all objects to be finalized */
GCObject **p = &g->mainthread->next;
GCObject *curr;
GCObject **lastnext = &g->tobefnz;
/* find last 'next' field in 'tobefnz' list (to insert elements in its end) */
while (*lastnext != NULL) lastnext = &gch(*lastnext)->next;
while ((curr = *p) != NULL) { /* traverse all finalizable objects */
lua_assert(ttisuserdata(gch(curr)) && !isfinalized(gco2u(curr)));
lua_assert(testbit(gch(curr)->marked, SEPARATED));
if (!(all || iswhite(curr))) /* not being collected? */
p = &gch(curr)->next; /* don't bother with it */
else {
l_setbit(gch(curr)->marked, FINALIZEDBIT); /* won't be finalized again */
deadmem += sizeudata(gco2u(curr));
*p = gch(curr)->next; /* remove 'curr' from 'rootgc' list */
/* link 'curr' at the end of 'tobefnz' list */
gch(curr)->next = *lastnext;
*lastnext = curr;
lastnext = &gch(curr)->next;
}
}
return deadmem;
}
void luaC_checkfinalizer (lua_State *L, Udata *u) {
global_State *g = G(L);
if (testbit(u->uv.marked, SEPARATED) || /* userdata is already separated... */
isfinalized(&u->uv) || /* ... or is finalized... */
gfasttm(g, u->uv.metatable, TM_GC) == NULL) /* or has no finalization? */
return; /* nothing to be done */
else { /* move 'u' to 2nd part of root list */
GCObject **p;
for (p = &g->rootgc; *p != obj2gco(u); p = &gch(*p)->next)
lua_assert(*p != obj2gco(g->mainthread)); /* 'u' must be in this list */
*p = u->uv.next; /* remove 'u' from root list */
u->uv.next = g->mainthread->next; /* re-link it in list */
g->mainthread->next = obj2gco(u);
l_setbit(u->uv.marked, SEPARATED); /* mark it as such */
}
}
/* }====================================================== */
/*
** {======================================================
** GC control
** =======================================================
*/
void luaC_freeall (lua_State *L) {
global_State *g = G(L);
int i;
lua_assert(g->tobefnz == NULL);
/* mask to collect all elements */
g->currentwhite = WHITEBITS | bitmask(SFIXEDBIT);
sweepwholelist(L, &g->rootgc);
lua_assert(g->rootgc == obj2gco(g->mainthread));
lua_assert(g->mainthread->next == NULL);
for (i = 0; i < g->strt.size; i++) /* free all string lists */
sweepwholelist(L, &g->strt.hash[i]);
lua_assert(g->strt.nuse == 0);
}
static void atomic (lua_State *L) {
global_State *g = G(L);
size_t udsize; /* total size of userdata to be finalized */
/* remark occasional upvalues of (maybe) dead threads */
g->gcstate = GCSatomic;
remarkupvals(g);
/* traverse objects cautch by write barrier and by 'remarkupvals' */
propagateall(g);
/* remark weak tables */
g->gray = g->weak;
g->weak = NULL;
lua_assert(!iswhite(obj2gco(g->mainthread)));
markobject(g, L); /* mark running thread */
markmt(g); /* mark basic metatables (again) */
propagateall(g);
traverselistofgrays(g, &g->ephemeron); /* remark ephemeron tables */
traverselistofgrays(g, &g->grayagain); /* remark gray again */
convergeephemerons(g);
udsize = luaC_separateudata(L, 0); /* separate userdata to be finalized */
markbeingfnz(g); /* mark userdata that will be finalized */
udsize += propagateall(g); /* remark, to propagate `preserveness' */
convergeephemerons(g);
/* remove collected objects from weak tables */
cleartable(g->weak);
cleartable(g->ephemeron);
cleartable(g->allweak);
/* flip current white */
g->currentwhite = cast_byte(otherwhite(g));
g->sweepstrgc = 0;
g->gcstate = GCSsweepstring;
g->estimate = g->totalbytes - udsize; /* first estimate */
}
#define correctestimate(g,s) {lu_mem old = g->totalbytes; s; \
lua_assert(old >= g->totalbytes); g->estimate -= old - g->totalbytes;}
static l_mem singlestep (lua_State *L) {
global_State *g = G(L);
/*lua_checkmemory(L);*/
switch (g->gcstate) {
case GCSpause: {
markroot(L); /* start a new collection */
return 0;
}
case GCSpropagate: {
if (g->gray)
return propagatemark(g);
else { /* no more `gray' objects */
atomic(L); /* finish mark phase */
return 0;
}
}
case GCSsweepstring: {
correctestimate(g, sweepwholelist(L, &g->strt.hash[g->sweepstrgc++]));
if (g->sweepstrgc >= g->strt.size) { /* nothing more to sweep? */
g->sweepgc = &g->rootgc;
g->gcstate = GCSsweep; /* sweep all other objects */
}
return GCSWEEPCOST;
}
case GCSsweep: {
correctestimate(g, g->sweepgc = sweeplist(L, g->sweepgc, GCSWEEPMAX));
if (*g->sweepgc == NULL) /* nothing more to sweep? */
g->gcstate = GCSfinalize; /* end sweep phase */
return GCSWEEPMAX*GCSWEEPCOST;
}
case GCSfinalize: {
if (g->tobefnz) {
GCTM(L, 1);
if (g->estimate > GCFINALIZECOST)
g->estimate -= GCFINALIZECOST;
return GCFINALIZECOST;
}
else {
correctestimate(g, checkSizes(L));
g->gcstate = GCSpause; /* end collection */
g->gcdept = 0;
return 0;
}
}
default: lua_assert(0); return 0;
}
}
void luaC_step (lua_State *L) {
global_State *g = G(L);
l_mem lim = (GCSTEPSIZE/100) * g->gcstepmul;
lua_assert(g->gckind == KGC_NORMAL);
if (lim == 0)
lim = (MAX_LUMEM-1)/2; /* no limit */
g->gcdept += g->totalbytes - g->GCthreshold;
do {
lim -= singlestep(L);
if (g->gcstate == GCSpause)
break;
} while (lim > 0);
if (g->gcstate != GCSpause) {
if (g->gcdept < GCSTEPSIZE)
g->GCthreshold = g->totalbytes + GCSTEPSIZE; /* - lim/g->gcstepmul;*/
else {
g->gcdept -= GCSTEPSIZE;
g->GCthreshold = g->totalbytes;
}
}
else {
lua_assert(g->totalbytes >= g->estimate);
setthreshold(g);
}
}
void luaC_fullgc (lua_State *L, int isemergency) {
global_State *g = G(L);
lua_assert(g->gckind == KGC_NORMAL);
g->gckind = isemergency ? KGC_EMERGENCY : KGC_FORCED;
if (g->gcstate <= GCSpropagate) {
/* reset other collector lists */
g->gray = NULL;
g->grayagain = NULL;
g->weak = g->ephemeron = g->allweak = NULL;
g->sweepstrgc = 0;
g->gcstate = GCSsweepstring;
}
lua_assert(g->gcstate != GCSpause && g->gcstate != GCSpropagate);
/* finish any pending sweep phase */
while (g->gcstate != GCSfinalize) {
lua_assert(issweep(g));
singlestep(L);
}
markroot(L);
/* run collector up to finalizers */
while (g->gcstate != GCSfinalize)
singlestep(L);
g->gckind = KGC_NORMAL;
if (!isemergency) { /* do not run finalizers during emergency GC */
while (g->gcstate != GCSpause)
singlestep(L);
}
setthreshold(g);
}
/* }====================================================== */
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