1 /*
2 ** $Id$
3 ** Garbage Collector
4 ** See Copyright Notice in lua.h
5 */
6
7 #define lgc_c
8 #define LUA_CORE
9
10 #include "lua.h"
11
12 #include "ldebug.h"
13 #include "ldo.h"
14 #include "lfunc.h"
15 #include "lgc.h"
16 #include "lmem.h"
17 #include "lobject.h"
18 #include "lstate.h"
19 #include "lstring.h"
20 #include "ltable.h"
21 #include "ltm.h"
22
23
24 #define GCSTEPSIZE 1024u
25 #define GCSWEEPMAX 40
26 #define GCSWEEPCOST 10
27 #define GCFINALIZECOST 100
28
29
30 #define maskmarks cast_byte(~(bitmask(BLACKBIT)|WHITEBITS))
31
32 #define makewhite(g,x) \
33 ((x)->gch.marked = cast_byte(((x)->gch.marked & maskmarks) | luaC_white(g)))
34
35 #define white2gray(x) reset2bits((x)->gch.marked, WHITE0BIT, WHITE1BIT)
36 #define black2gray(x) resetbit((x)->gch.marked, BLACKBIT)
37
38 #define stringmark(s) reset2bits((s)->tsv.marked, WHITE0BIT, WHITE1BIT)
39
40
41 #define isfinalized(u) testbit((u)->marked, FINALIZEDBIT)
42 #define markfinalized(u) l_setbit((u)->marked, FINALIZEDBIT)
43
44
45 #define KEYWEAK bitmask(KEYWEAKBIT)
46 #define VALUEWEAK bitmask(VALUEWEAKBIT)
47
48
49
50 #define markvalue(g,o) { checkconsistency(o); \
51 if (iscollectable(o) && iswhite(gcvalue(o))) reallymarkobject(g,gcvalue(o)); }
52
53 #define markobject(g,t) { if (iswhite(obj2gco(t))) \
54 reallymarkobject(g, obj2gco(t)); }
55
56
57 #define setthreshold(g) (g->GCthreshold = (g->estimate/100) * g->gcpause)
58
59
removeentry(Node * n)60 static void removeentry (Node *n) {
61 lua_assert(ttisnil(gval(n)));
62 if (iscollectable(gkey(n)))
63 setttype(gkey(n), LUA_TDEADKEY); /* dead key; remove it */
64 }
65
66
reallymarkobject(global_State * g,GCObject * o)67 static void reallymarkobject (global_State *g, GCObject *o) {
68 lua_assert(iswhite(o) && !isdead(g, o));
69 white2gray(o);
70 switch (o->gch.tt) {
71 case LUA_TSTRING: {
72 return;
73 }
74 case LUA_TUSERDATA: {
75 Table *mt = gco2u(o)->metatable;
76 gray2black(o); /* udata are never gray */
77 if (mt) markobject(g, mt);
78 markobject(g, gco2u(o)->env);
79 return;
80 }
81 case LUA_TUPVAL: {
82 UpVal *uv = gco2uv(o);
83 markvalue(g, uv->v);
84 if (uv->v == &uv->u.value) /* closed? */
85 gray2black(o); /* open upvalues are never black */
86 return;
87 }
88 case LUA_TFUNCTION: {
89 gco2cl(o)->c.gclist = g->gray;
90 g->gray = o;
91 break;
92 }
93 case LUA_TTABLE: {
94 gco2h(o)->gclist = g->gray;
95 g->gray = o;
96 break;
97 }
98 case LUA_TTHREAD: {
99 gco2th(o)->gclist = g->gray;
100 g->gray = o;
101 break;
102 }
103 case LUA_TPROTO: {
104 gco2p(o)->gclist = g->gray;
105 g->gray = o;
106 break;
107 }
108 default: lua_assert(0);
109 }
110 }
111
112
marktmu(global_State * g)113 static void marktmu (global_State *g) {
114 GCObject *u = g->tmudata;
115 if (u) {
116 do {
117 u = u->gch.next;
118 makewhite(g, u); /* may be marked, if left from previous GC */
119 reallymarkobject(g, u);
120 } while (u != g->tmudata);
121 }
122 }
123
124
125 /* move `dead' udata that need finalization to list `tmudata' */
luaC_separateudata(lua_State * L,int all)126 size_t luaC_separateudata (lua_State *L, int all) {
127 global_State *g = G(L);
128 size_t deadmem = 0;
129 GCObject **p = &g->mainthread->next;
130 GCObject *curr;
131 while ((curr = *p) != NULL) {
132 if (!(iswhite(curr) || all) || isfinalized(gco2u(curr)))
133 p = &curr->gch.next; /* don't bother with them */
134 else if (fasttm(L, gco2u(curr)->metatable, TM_GC) == NULL) {
135 markfinalized(gco2u(curr)); /* don't need finalization */
136 p = &curr->gch.next;
137 }
138 else { /* must call its gc method */
139 deadmem += sizeudata(gco2u(curr));
140 markfinalized(gco2u(curr));
141 *p = curr->gch.next;
142 /* link `curr' at the end of `tmudata' list */
143 if (g->tmudata == NULL) /* list is empty? */
144 g->tmudata = curr->gch.next = curr; /* creates a circular list */
145 else {
146 curr->gch.next = g->tmudata->gch.next;
147 g->tmudata->gch.next = curr;
148 g->tmudata = curr;
149 }
150 }
151 }
152 return deadmem;
153 }
154
155
traversetable(global_State * g,Table * h)156 static int traversetable (global_State *g, Table *h) {
157 int i;
158 int weakkey = 0;
159 int weakvalue = 0;
160 const TValue *mode;
161 if (h->metatable)
162 markobject(g, h->metatable);
163 mode = gfasttm(g, h->metatable, TM_MODE);
164 if (mode && ttisstring(mode)) { /* is there a weak mode? */
165 weakkey = (strchr(svalue(mode), 'k') != NULL);
166 weakvalue = (strchr(svalue(mode), 'v') != NULL);
167 if (weakkey || weakvalue) { /* is really weak? */
168 h->marked &= ~(KEYWEAK | VALUEWEAK); /* clear bits */
169 h->marked |= cast_byte((weakkey << KEYWEAKBIT) |
170 (weakvalue << VALUEWEAKBIT));
171 h->gclist = g->weak; /* must be cleared after GC, ... */
172 g->weak = obj2gco(h); /* ... so put in the appropriate list */
173 }
174 }
175 if (weakkey && weakvalue) return 1;
176 if (!weakvalue) {
177 i = h->sizearray;
178 while (i--)
179 markvalue(g, &h->array[i]);
180 }
181 i = sizenode(h);
182 while (i--) {
183 Node *n = gnode(h, i);
184 lua_assert(ttype(gkey(n)) != LUA_TDEADKEY || ttisnil(gval(n)));
185 if (ttisnil(gval(n)))
186 removeentry(n); /* remove empty entries */
187 else {
188 lua_assert(!ttisnil(gkey(n)));
189 if (!weakkey) markvalue(g, gkey(n));
190 if (!weakvalue) markvalue(g, gval(n));
191 }
192 }
193 return weakkey || weakvalue;
194 }
195
196
197 /*
198 ** All marks are conditional because a GC may happen while the
199 ** prototype is still being created
200 */
traverseproto(global_State * g,Proto * f)201 static void traverseproto (global_State *g, Proto *f) {
202 int i;
203 if (f->source) stringmark(f->source);
204 for (i=0; i<f->sizek; i++) /* mark literals */
205 markvalue(g, &f->k[i]);
206 for (i=0; i<f->sizeupvalues; i++) { /* mark upvalue names */
207 if (f->upvalues[i])
208 stringmark(f->upvalues[i]);
209 }
210 for (i=0; i<f->sizep; i++) { /* mark nested protos */
211 if (f->p[i])
212 markobject(g, f->p[i]);
213 }
214 for (i=0; i<f->sizelocvars; i++) { /* mark local-variable names */
215 if (f->locvars[i].varname)
216 stringmark(f->locvars[i].varname);
217 }
218 }
219
220
221
traverseclosure(global_State * g,Closure * cl)222 static void traverseclosure (global_State *g, Closure *cl) {
223 markobject(g, cl->c.env);
224 if (cl->c.isC) {
225 int i;
226 for (i=0; i<cl->c.nupvalues; i++) /* mark its upvalues */
227 markvalue(g, &cl->c.upvalue[i]);
228 }
229 else {
230 int i;
231 lua_assert(cl->l.nupvalues == cl->l.p->nups);
232 markobject(g, cl->l.p);
233 for (i=0; i<cl->l.nupvalues; i++) /* mark its upvalues */
234 markobject(g, cl->l.upvals[i]);
235 }
236 }
237
238
checkstacksizes(lua_State * L,StkId max)239 static void checkstacksizes (lua_State *L, StkId max) {
240 int ci_used = cast_int(L->ci - L->base_ci); /* number of `ci' in use */
241 int s_used = cast_int(max - L->stack); /* part of stack in use */
242 if (L->size_ci > LUAI_MAXCALLS) /* handling overflow? */
243 return; /* do not touch the stacks */
244 if (4*ci_used < L->size_ci && 2*BASIC_CI_SIZE < L->size_ci)
245 luaD_reallocCI(L, L->size_ci/2); /* still big enough... */
246 condhardstacktests(luaD_reallocCI(L, ci_used + 1));
247 if (4*s_used < L->stacksize &&
248 2*(BASIC_STACK_SIZE+EXTRA_STACK) < L->stacksize)
249 luaD_reallocstack(L, L->stacksize/2); /* still big enough... */
250 condhardstacktests(luaD_reallocstack(L, s_used));
251 }
252
253
traversestack(global_State * g,lua_State * l)254 static void traversestack (global_State *g, lua_State *l) {
255 StkId o, lim;
256 CallInfo *ci;
257 markvalue(g, gt(l));
258 lim = l->top;
259 for (ci = l->base_ci; ci <= l->ci; ci++) {
260 lua_assert(ci->top <= l->stack_last);
261 if (lim < ci->top) lim = ci->top;
262 }
263 for (o = l->stack; o < l->top; o++)
264 markvalue(g, o);
265 for (; o <= lim; o++)
266 setnilvalue(o);
267 checkstacksizes(l, lim);
268 }
269
270
271 /*
272 ** traverse one gray object, turning it to black.
273 ** Returns `quantity' traversed.
274 */
propagatemark(global_State * g)275 static l_mem propagatemark (global_State *g) {
276 GCObject *o = g->gray;
277 lua_assert(isgray(o));
278 gray2black(o);
279 switch (o->gch.tt) {
280 case LUA_TTABLE: {
281 Table *h = gco2h(o);
282 g->gray = h->gclist;
283 if (traversetable(g, h)) /* table is weak? */
284 black2gray(o); /* keep it gray */
285 return sizeof(Table) + sizeof(TValue) * h->sizearray +
286 sizeof(Node) * sizenode(h);
287 }
288 case LUA_TFUNCTION: {
289 Closure *cl = gco2cl(o);
290 g->gray = cl->c.gclist;
291 traverseclosure(g, cl);
292 return (cl->c.isC) ? sizeCclosure(cl->c.nupvalues) :
293 sizeLclosure(cl->l.nupvalues);
294 }
295 case LUA_TTHREAD: {
296 lua_State *th = gco2th(o);
297 g->gray = th->gclist;
298 th->gclist = g->grayagain;
299 g->grayagain = o;
300 black2gray(o);
301 traversestack(g, th);
302 return sizeof(lua_State) + sizeof(TValue) * th->stacksize +
303 sizeof(CallInfo) * th->size_ci;
304 }
305 case LUA_TPROTO: {
306 Proto *p = gco2p(o);
307 g->gray = p->gclist;
308 traverseproto(g, p);
309 return sizeof(Proto) + sizeof(Instruction) * p->sizecode +
310 sizeof(Proto *) * p->sizep +
311 sizeof(TValue) * p->sizek +
312 sizeof(int) * p->sizelineinfo +
313 sizeof(LocVar) * p->sizelocvars +
314 sizeof(TString *) * p->sizeupvalues;
315 }
316 default: lua_assert(0); return 0;
317 }
318 }
319
320
propagateall(global_State * g)321 static size_t propagateall (global_State *g) {
322 size_t m = 0;
323 while (g->gray) m += propagatemark(g);
324 return m;
325 }
326
327
328 /*
329 ** The next function tells whether a key or value can be cleared from
330 ** a weak table. Non-collectable objects are never removed from weak
331 ** tables. Strings behave as `values', so are never removed too. for
332 ** other objects: if really collected, cannot keep them; for userdata
333 ** being finalized, keep them in keys, but not in values
334 */
iscleared(const TValue * o,int iskey)335 static int iscleared (const TValue *o, int iskey) {
336 if (!iscollectable(o)) return 0;
337 if (ttisstring(o)) {
338 stringmark(rawtsvalue(o)); /* strings are `values', so are never weak */
339 return 0;
340 }
341 return iswhite(gcvalue(o)) ||
342 (ttisuserdata(o) && (!iskey && isfinalized(uvalue(o))));
343 }
344
345
346 /*
347 ** clear collected entries from weaktables
348 */
cleartable(GCObject * l)349 static void cleartable (GCObject *l) {
350 while (l) {
351 Table *h = gco2h(l);
352 int i = h->sizearray;
353 lua_assert(testbit(h->marked, VALUEWEAKBIT) ||
354 testbit(h->marked, KEYWEAKBIT));
355 if (testbit(h->marked, VALUEWEAKBIT)) {
356 while (i--) {
357 TValue *o = &h->array[i];
358 if (iscleared(o, 0)) /* value was collected? */
359 setnilvalue(o); /* remove value */
360 }
361 }
362 i = sizenode(h);
363 while (i--) {
364 Node *n = gnode(h, i);
365 if (!ttisnil(gval(n)) && /* non-empty entry? */
366 (iscleared(key2tval(n), 1) || iscleared(gval(n), 0))) {
367 setnilvalue(gval(n)); /* remove value ... */
368 removeentry(n); /* remove entry from table */
369 }
370 }
371 l = h->gclist;
372 }
373 }
374
375
freeobj(lua_State * L,GCObject * o)376 static void freeobj (lua_State *L, GCObject *o) {
377 switch (o->gch.tt) {
378 case LUA_TPROTO: luaF_freeproto(L, gco2p(o)); break;
379 case LUA_TFUNCTION: luaF_freeclosure(L, gco2cl(o)); break;
380 case LUA_TUPVAL: luaF_freeupval(L, gco2uv(o)); break;
381 case LUA_TTABLE: luaH_free(L, gco2h(o)); break;
382 case LUA_TTHREAD: {
383 lua_assert(gco2th(o) != L && gco2th(o) != G(L)->mainthread);
384 luaE_freethread(L, gco2th(o));
385 break;
386 }
387 case LUA_TSTRING: {
388 G(L)->strt.nuse--;
389 luaM_freemem(L, o, sizestring(gco2ts(o)));
390 break;
391 }
392 case LUA_TUSERDATA: {
393 luaM_freemem(L, o, sizeudata(gco2u(o)));
394 break;
395 }
396 default: lua_assert(0);
397 }
398 }
399
400
401
402 #define sweepwholelist(L,p) sweeplist(L,p,MAX_LUMEM)
403
404
sweeplist(lua_State * L,GCObject ** p,lu_mem count)405 static GCObject **sweeplist (lua_State *L, GCObject **p, lu_mem count) {
406 GCObject *curr;
407 global_State *g = G(L);
408 int deadmask = otherwhite(g);
409 while ((curr = *p) != NULL && count-- > 0) {
410 if (curr->gch.tt == LUA_TTHREAD) /* sweep open upvalues of each thread */
411 sweepwholelist(L, &gco2th(curr)->openupval);
412 if ((curr->gch.marked ^ WHITEBITS) & deadmask) { /* not dead? */
413 lua_assert(!isdead(g, curr) || testbit(curr->gch.marked, FIXEDBIT));
414 makewhite(g, curr); /* make it white (for next cycle) */
415 p = &curr->gch.next;
416 }
417 else { /* must erase `curr' */
418 lua_assert(isdead(g, curr) || deadmask == bitmask(SFIXEDBIT));
419 *p = curr->gch.next;
420 if (curr == g->rootgc) /* is the first element of the list? */
421 g->rootgc = curr->gch.next; /* adjust first */
422 freeobj(L, curr);
423 }
424 }
425 return p;
426 }
427
428
checkSizes(lua_State * L)429 static void checkSizes (lua_State *L) {
430 global_State *g = G(L);
431 /* check size of string hash */
432 if (g->strt.nuse < cast(lu_int32, g->strt.size/4) &&
433 g->strt.size > MINSTRTABSIZE*2)
434 luaS_resize(L, g->strt.size/2); /* table is too big */
435 /* check size of buffer */
436 if (luaZ_sizebuffer(&g->buff) > LUA_MINBUFFER*2) { /* buffer too big? */
437 size_t newsize = luaZ_sizebuffer(&g->buff) / 2;
438 luaZ_resizebuffer(L, &g->buff, newsize);
439 }
440 }
441
442
GCTM(lua_State * L)443 static void GCTM (lua_State *L) {
444 global_State *g = G(L);
445 GCObject *o = g->tmudata->gch.next; /* get first element */
446 Udata *udata = rawgco2u(o);
447 const TValue *tm;
448 /* remove udata from `tmudata' */
449 if (o == g->tmudata) /* last element? */
450 g->tmudata = NULL;
451 else
452 g->tmudata->gch.next = udata->uv.next;
453 udata->uv.next = g->mainthread->next; /* return it to `root' list */
454 g->mainthread->next = o;
455 makewhite(g, o);
456 tm = fasttm(L, udata->uv.metatable, TM_GC);
457 if (tm != NULL) {
458 lu_byte oldah = L->allowhook;
459 lu_mem oldt = g->GCthreshold;
460 L->allowhook = 0; /* stop debug hooks during GC tag method */
461 g->GCthreshold = 2*g->totalbytes; /* avoid GC steps */
462 setobj2s(L, L->top, tm);
463 setuvalue(L, L->top+1, udata);
464 L->top += 2;
465 luaD_call(L, L->top - 2, 0);
466 L->allowhook = oldah; /* restore hooks */
467 g->GCthreshold = oldt; /* restore threshold */
468 }
469 }
470
471
472 /*
473 ** Call all GC tag methods
474 */
luaC_callGCTM(lua_State * L)475 void luaC_callGCTM (lua_State *L) {
476 while (G(L)->tmudata)
477 GCTM(L);
478 }
479
480
luaC_freeall(lua_State * L)481 void luaC_freeall (lua_State *L) {
482 global_State *g = G(L);
483 int i;
484 g->currentwhite = WHITEBITS | bitmask(SFIXEDBIT); /* mask to collect all elements */
485 sweepwholelist(L, &g->rootgc);
486 for (i = 0; i < g->strt.size; i++) /* free all string lists */
487 sweepwholelist(L, &g->strt.hash[i]);
488 }
489
490
markmt(global_State * g)491 static void markmt (global_State *g) {
492 int i;
493 for (i=0; i<NUM_TAGS; i++)
494 if (g->mt[i]) markobject(g, g->mt[i]);
495 }
496
497
498 /* mark root set */
markroot(lua_State * L)499 static void markroot (lua_State *L) {
500 global_State *g = G(L);
501 g->gray = NULL;
502 g->grayagain = NULL;
503 g->weak = NULL;
504 markobject(g, g->mainthread);
505 /* make global table be traversed before main stack */
506 markvalue(g, gt(g->mainthread));
507 markvalue(g, registry(L));
508 markmt(g);
509 g->gcstate = GCSpropagate;
510 }
511
512
remarkupvals(global_State * g)513 static void remarkupvals (global_State *g) {
514 UpVal *uv;
515 for (uv = g->uvhead.u.l.next; uv != &g->uvhead; uv = uv->u.l.next) {
516 lua_assert(uv->u.l.next->u.l.prev == uv && uv->u.l.prev->u.l.next == uv);
517 if (isgray(obj2gco(uv)))
518 markvalue(g, uv->v);
519 }
520 }
521
522
atomic(lua_State * L)523 static void atomic (lua_State *L) {
524 global_State *g = G(L);
525 size_t udsize; /* total size of userdata to be finalized */
526 /* remark occasional upvalues of (maybe) dead threads */
527 remarkupvals(g);
528 /* traverse objects cautch by write barrier and by 'remarkupvals' */
529 propagateall(g);
530 /* remark weak tables */
531 g->gray = g->weak;
532 g->weak = NULL;
533 lua_assert(!iswhite(obj2gco(g->mainthread)));
534 markobject(g, L); /* mark running thread */
535 markmt(g); /* mark basic metatables (again) */
536 propagateall(g);
537 /* remark gray again */
538 g->gray = g->grayagain;
539 g->grayagain = NULL;
540 propagateall(g);
541 udsize = luaC_separateudata(L, 0); /* separate userdata to be finalized */
542 marktmu(g); /* mark `preserved' userdata */
543 udsize += propagateall(g); /* remark, to propagate `preserveness' */
544 cleartable(g->weak); /* remove collected objects from weak tables */
545 /* flip current white */
546 g->currentwhite = cast_byte(otherwhite(g));
547 g->sweepstrgc = 0;
548 g->sweepgc = &g->rootgc;
549 g->gcstate = GCSsweepstring;
550 g->estimate = g->totalbytes - udsize; /* first estimate */
551 }
552
553
singlestep(lua_State * L)554 static l_mem singlestep (lua_State *L) {
555 global_State *g = G(L);
556 /*lua_checkmemory(L);*/
557 switch (g->gcstate) {
558 case GCSpause: {
559 markroot(L); /* start a new collection */
560 return 0;
561 }
562 case GCSpropagate: {
563 if (g->gray)
564 return propagatemark(g);
565 else { /* no more `gray' objects */
566 atomic(L); /* finish mark phase */
567 return 0;
568 }
569 }
570 case GCSsweepstring: {
571 lu_mem old = g->totalbytes;
572 sweepwholelist(L, &g->strt.hash[g->sweepstrgc++]);
573 if (g->sweepstrgc >= g->strt.size) /* nothing more to sweep? */
574 g->gcstate = GCSsweep; /* end sweep-string phase */
575 lua_assert(old >= g->totalbytes);
576 g->estimate -= old - g->totalbytes;
577 return GCSWEEPCOST;
578 }
579 case GCSsweep: {
580 lu_mem old = g->totalbytes;
581 g->sweepgc = sweeplist(L, g->sweepgc, GCSWEEPMAX);
582 if (*g->sweepgc == NULL) { /* nothing more to sweep? */
583 checkSizes(L);
584 g->gcstate = GCSfinalize; /* end sweep phase */
585 }
586 lua_assert(old >= g->totalbytes);
587 g->estimate -= old - g->totalbytes;
588 return GCSWEEPMAX*GCSWEEPCOST;
589 }
590 case GCSfinalize: {
591 if (g->tmudata) {
592 GCTM(L);
593 if (g->estimate > GCFINALIZECOST)
594 g->estimate -= GCFINALIZECOST;
595 return GCFINALIZECOST;
596 }
597 else {
598 g->gcstate = GCSpause; /* end collection */
599 g->gcdept = 0;
600 return 0;
601 }
602 }
603 default: lua_assert(0); return 0;
604 }
605 }
606
607
luaC_step(lua_State * L)608 void luaC_step (lua_State *L) {
609 global_State *g = G(L);
610 l_mem lim = (GCSTEPSIZE/100) * g->gcstepmul;
611 if (lim == 0)
612 lim = (MAX_LUMEM-1)/2; /* no limit */
613 g->gcdept += g->totalbytes - g->GCthreshold;
614 do {
615 lim -= singlestep(L);
616 if (g->gcstate == GCSpause)
617 break;
618 } while (lim > 0);
619 if (g->gcstate != GCSpause) {
620 if (g->gcdept < GCSTEPSIZE)
621 g->GCthreshold = g->totalbytes + GCSTEPSIZE; /* - lim/g->gcstepmul;*/
622 else {
623 g->gcdept -= GCSTEPSIZE;
624 g->GCthreshold = g->totalbytes;
625 }
626 }
627 else {
628 lua_assert(g->totalbytes >= g->estimate);
629 setthreshold(g);
630 }
631 }
632
633
luaC_fullgc(lua_State * L)634 void luaC_fullgc (lua_State *L) {
635 global_State *g = G(L);
636 if (g->gcstate <= GCSpropagate) {
637 /* reset sweep marks to sweep all elements (returning them to white) */
638 g->sweepstrgc = 0;
639 g->sweepgc = &g->rootgc;
640 /* reset other collector lists */
641 g->gray = NULL;
642 g->grayagain = NULL;
643 g->weak = NULL;
644 g->gcstate = GCSsweepstring;
645 }
646 lua_assert(g->gcstate != GCSpause && g->gcstate != GCSpropagate);
647 /* finish any pending sweep phase */
648 while (g->gcstate != GCSfinalize) {
649 lua_assert(g->gcstate == GCSsweepstring || g->gcstate == GCSsweep);
650 singlestep(L);
651 }
652 markroot(L);
653 while (g->gcstate != GCSpause) {
654 singlestep(L);
655 }
656 setthreshold(g);
657 }
658
659
luaC_barrierf(lua_State * L,GCObject * o,GCObject * v)660 void luaC_barrierf (lua_State *L, GCObject *o, GCObject *v) {
661 global_State *g = G(L);
662 lua_assert(isblack(o) && iswhite(v) && !isdead(g, v) && !isdead(g, o));
663 lua_assert(g->gcstate != GCSfinalize && g->gcstate != GCSpause);
664 lua_assert(ttype(&o->gch) != LUA_TTABLE);
665 /* must keep invariant? */
666 if (g->gcstate == GCSpropagate)
667 reallymarkobject(g, v); /* restore invariant */
668 else /* don't mind */
669 makewhite(g, o); /* mark as white just to avoid other barriers */
670 }
671
672
luaC_barrierback(lua_State * L,Table * t)673 void luaC_barrierback (lua_State *L, Table *t) {
674 global_State *g = G(L);
675 GCObject *o = obj2gco(t);
676 lua_assert(isblack(o) && !isdead(g, o));
677 lua_assert(g->gcstate != GCSfinalize && g->gcstate != GCSpause);
678 black2gray(o); /* make table gray (again) */
679 t->gclist = g->grayagain;
680 g->grayagain = o;
681 }
682
683
luaC_link(lua_State * L,GCObject * o,lu_byte tt)684 void luaC_link (lua_State *L, GCObject *o, lu_byte tt) {
685 global_State *g = G(L);
686 o->gch.next = g->rootgc;
687 g->rootgc = o;
688 o->gch.marked = luaC_white(g);
689 o->gch.tt = tt;
690 }
691
692
luaC_linkupval(lua_State * L,UpVal * uv)693 void luaC_linkupval (lua_State *L, UpVal *uv) {
694 global_State *g = G(L);
695 GCObject *o = obj2gco(uv);
696 o->gch.next = g->rootgc; /* link upvalue into `rootgc' list */
697 g->rootgc = o;
698 if (isgray(o)) {
699 if (g->gcstate == GCSpropagate) {
700 gray2black(o); /* closed upvalues need barrier */
701 luaC_barrier(L, uv, uv->v);
702 }
703 else { /* sweep phase: sweep it (turning it into white) */
704 makewhite(g, o);
705 lua_assert(g->gcstate != GCSfinalize && g->gcstate != GCSpause);
706 }
707 }
708 }
709