lgc.c 21 KB

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  1. /*
  2. ** $Id: lgc.c,v 2.38.1.1 2007/12/27 13:02:25 roberto Exp $
  3. ** Garbage Collector
  4. ** See Copyright Notice in lua.h
  5. */
  6. #define lgc_c
  7. #define LUA_CORE
  8. #define LUAC_CROSS_FILE
  9. #include "lua.h"
  10. #include C_HEADER_STRING
  11. #include "ldebug.h"
  12. #include "ldo.h"
  13. #include "lfunc.h"
  14. #include "lgc.h"
  15. #include "lmem.h"
  16. #include "lobject.h"
  17. #include "lstate.h"
  18. #include "lstring.h"
  19. #include "ltable.h"
  20. #include "ltm.h"
  21. #include "lrotable.h"
  22. #define GCSTEPSIZE 1024u
  23. #define GCSWEEPMAX 40
  24. #define GCSWEEPCOST 10
  25. #define GCFINALIZECOST 100
  26. #define maskmarks cast_byte(~(bitmask(BLACKBIT)|WHITEBITS))
  27. #define makewhite(g,x) \
  28. ((x)->gch.marked = cast_byte(((x)->gch.marked & maskmarks) | luaC_white(g)))
  29. #define white2gray(x) reset2bits((x)->gch.marked, WHITE0BIT, WHITE1BIT)
  30. #define black2gray(x) resetbit((x)->gch.marked, BLACKBIT)
  31. #define stringmark(s) reset2bits((s)->tsv.marked, WHITE0BIT, WHITE1BIT)
  32. #define isfinalized(u) testbit((u)->marked, FINALIZEDBIT)
  33. #define markfinalized(u) l_setbit((u)->marked, FINALIZEDBIT)
  34. #define KEYWEAK bitmask(KEYWEAKBIT)
  35. #define VALUEWEAK bitmask(VALUEWEAKBIT)
  36. #define markvalue(g,o) { checkconsistency(o); \
  37. if (iscollectable(o) && iswhite(gcvalue(o))) reallymarkobject(g,gcvalue(o)); }
  38. #define markobject(g,t) { if (iswhite(obj2gco(t))) \
  39. reallymarkobject(g, obj2gco(t)); }
  40. #define setthreshold(g) (g->GCthreshold = (g->estimate/100) * g->gcpause)
  41. static void removeentry (Node *n) {
  42. lua_assert(ttisnil(gval(n)));
  43. if (iscollectable(gkey(n)))
  44. setttype(gkey(n), LUA_TDEADKEY); /* dead key; remove it */
  45. }
  46. static void reallymarkobject (global_State *g, GCObject *o) {
  47. lua_assert(iswhite(o) && !isdead(g, o));
  48. white2gray(o);
  49. switch (o->gch.tt) {
  50. case LUA_TSTRING: {
  51. return;
  52. }
  53. case LUA_TUSERDATA: {
  54. Table *mt = gco2u(o)->metatable;
  55. gray2black(o); /* udata are never gray */
  56. if (mt && !luaR_isrotable(mt)) markobject(g, mt);
  57. markobject(g, gco2u(o)->env);
  58. return;
  59. }
  60. case LUA_TUPVAL: {
  61. UpVal *uv = gco2uv(o);
  62. markvalue(g, uv->v);
  63. if (uv->v == &uv->u.value) /* closed? */
  64. gray2black(o); /* open upvalues are never black */
  65. return;
  66. }
  67. case LUA_TFUNCTION: {
  68. gco2cl(o)->c.gclist = g->gray;
  69. g->gray = o;
  70. break;
  71. }
  72. case LUA_TTABLE: {
  73. gco2h(o)->gclist = g->gray;
  74. g->gray = o;
  75. break;
  76. }
  77. case LUA_TTHREAD: {
  78. gco2th(o)->gclist = g->gray;
  79. g->gray = o;
  80. break;
  81. }
  82. case LUA_TPROTO: {
  83. gco2p(o)->gclist = g->gray;
  84. g->gray = o;
  85. break;
  86. }
  87. default: lua_assert(0);
  88. }
  89. }
  90. static void marktmu (global_State *g) {
  91. GCObject *u = g->tmudata;
  92. if (u) {
  93. do {
  94. u = u->gch.next;
  95. makewhite(g, u); /* may be marked, if left from previous GC */
  96. reallymarkobject(g, u);
  97. } while (u != g->tmudata);
  98. }
  99. }
  100. /* move `dead' udata that need finalization to list `tmudata' */
  101. size_t luaC_separateudata (lua_State *L, int all) {
  102. global_State *g = G(L);
  103. size_t deadmem = 0;
  104. GCObject **p = &g->mainthread->next;
  105. GCObject *curr;
  106. while ((curr = *p) != NULL) {
  107. if (!(iswhite(curr) || all) || isfinalized(gco2u(curr)))
  108. p = &curr->gch.next; /* don't bother with them */
  109. else if (fasttm(L, gco2u(curr)->metatable, TM_GC) == NULL) {
  110. markfinalized(gco2u(curr)); /* don't need finalization */
  111. p = &curr->gch.next;
  112. }
  113. else { /* must call its gc method */
  114. deadmem += sizeudata(gco2u(curr));
  115. markfinalized(gco2u(curr));
  116. *p = curr->gch.next;
  117. /* link `curr' at the end of `tmudata' list */
  118. if (g->tmudata == NULL) /* list is empty? */
  119. g->tmudata = curr->gch.next = curr; /* creates a circular list */
  120. else {
  121. curr->gch.next = g->tmudata->gch.next;
  122. g->tmudata->gch.next = curr;
  123. g->tmudata = curr;
  124. }
  125. }
  126. }
  127. return deadmem;
  128. }
  129. static int traversetable (global_State *g, Table *h) {
  130. int i;
  131. int weakkey = 0;
  132. int weakvalue = 0;
  133. const TValue *mode;
  134. if (h->metatable && !luaR_isrotable(h->metatable))
  135. markobject(g, h->metatable);
  136. mode = gfasttm(g, h->metatable, TM_MODE);
  137. if (mode && ttisstring(mode)) { /* is there a weak mode? */
  138. weakkey = (c_strchr(svalue(mode), 'k') != NULL);
  139. weakvalue = (c_strchr(svalue(mode), 'v') != NULL);
  140. if (weakkey || weakvalue) { /* is really weak? */
  141. h->marked &= ~(KEYWEAK | VALUEWEAK); /* clear bits */
  142. h->marked |= cast_byte((weakkey << KEYWEAKBIT) |
  143. (weakvalue << VALUEWEAKBIT));
  144. h->gclist = g->weak; /* must be cleared after GC, ... */
  145. g->weak = obj2gco(h); /* ... so put in the appropriate list */
  146. }
  147. }
  148. if (weakkey && weakvalue) return 1;
  149. if (!weakvalue) {
  150. i = h->sizearray;
  151. while (i--)
  152. markvalue(g, &h->array[i]);
  153. }
  154. i = sizenode(h);
  155. while (i--) {
  156. Node *n = gnode(h, i);
  157. lua_assert(ttype(gkey(n)) != LUA_TDEADKEY || ttisnil(gval(n)));
  158. if (ttisnil(gval(n)))
  159. removeentry(n); /* remove empty entries */
  160. else {
  161. lua_assert(!ttisnil(gkey(n)));
  162. if (!weakkey) markvalue(g, gkey(n));
  163. if (!weakvalue) markvalue(g, gval(n));
  164. }
  165. }
  166. return weakkey || weakvalue;
  167. }
  168. /*
  169. ** All marks are conditional because a GC may happen while the
  170. ** prototype is still being created
  171. */
  172. static void traverseproto (global_State *g, Proto *f) {
  173. int i;
  174. if (f->source) stringmark(f->source);
  175. for (i=0; i<f->sizek; i++) /* mark literals */
  176. markvalue(g, &f->k[i]);
  177. for (i=0; i<f->sizeupvalues; i++) { /* mark upvalue names */
  178. if (f->upvalues[i])
  179. stringmark(f->upvalues[i]);
  180. }
  181. for (i=0; i<f->sizep; i++) { /* mark nested protos */
  182. if (f->p[i])
  183. markobject(g, f->p[i]);
  184. }
  185. for (i=0; i<f->sizelocvars; i++) { /* mark local-variable names */
  186. if (f->locvars[i].varname)
  187. stringmark(f->locvars[i].varname);
  188. }
  189. }
  190. static void traverseclosure (global_State *g, Closure *cl) {
  191. markobject(g, cl->c.env);
  192. if (cl->c.isC) {
  193. int i;
  194. for (i=0; i<cl->c.nupvalues; i++) /* mark its upvalues */
  195. markvalue(g, &cl->c.upvalue[i]);
  196. }
  197. else {
  198. int i;
  199. lua_assert(cl->l.nupvalues == cl->l.p->nups);
  200. markobject(g, cl->l.p);
  201. for (i=0; i<cl->l.nupvalues; i++) { /* mark its upvalues */
  202. if(cl->l.upvals[i])
  203. markobject(g, cl->l.upvals[i]);
  204. }
  205. }
  206. }
  207. static void checkstacksizes (lua_State *L, StkId max) {
  208. int ci_used = cast_int(L->ci - L->base_ci); /* number of `ci' in use */
  209. int s_used = cast_int(max - L->stack); /* part of stack in use */
  210. if (L->size_ci > LUAI_MAXCALLS) /* handling overflow? */
  211. return; /* do not touch the stacks */
  212. if (4*ci_used < L->size_ci && 2*BASIC_CI_SIZE < L->size_ci)
  213. luaD_reallocCI(L, L->size_ci/2); /* still big enough... */
  214. condhardstacktests(luaD_reallocCI(L, ci_used + 1));
  215. if (4*s_used < L->stacksize &&
  216. 2*(BASIC_STACK_SIZE+EXTRA_STACK) < L->stacksize)
  217. luaD_reallocstack(L, L->stacksize/2); /* still big enough... */
  218. condhardstacktests(luaD_reallocstack(L, s_used));
  219. }
  220. static void traversestack (global_State *g, lua_State *l) {
  221. StkId o, lim;
  222. CallInfo *ci;
  223. markvalue(g, gt(l));
  224. lim = l->top;
  225. if(l->stack == NULL) return; /* no stack to traverse */
  226. for (ci = l->base_ci; ci <= l->ci; ci++) {
  227. lua_assert(ci->top <= l->stack_last);
  228. if (lim < ci->top) lim = ci->top;
  229. }
  230. for (o = l->stack; o < l->top; o++)
  231. markvalue(g, o);
  232. for (; o <= lim; o++)
  233. setnilvalue(o);
  234. if (!isfixedstack(l)) /* if stack size is fixed, can't resize it. */
  235. checkstacksizes(l, lim);
  236. }
  237. /*
  238. ** traverse one gray object, turning it to black.
  239. ** Returns `quantity' traversed.
  240. */
  241. static l_mem propagatemark (global_State *g) {
  242. GCObject *o = g->gray;
  243. lua_assert(isgray(o));
  244. gray2black(o);
  245. switch (o->gch.tt) {
  246. case LUA_TTABLE: {
  247. Table *h = gco2h(o);
  248. g->gray = h->gclist;
  249. if (traversetable(g, h)) /* table is weak? */
  250. black2gray(o); /* keep it gray */
  251. return sizeof(Table) + sizeof(TValue) * h->sizearray +
  252. sizeof(Node) * sizenode(h);
  253. }
  254. case LUA_TFUNCTION: {
  255. Closure *cl = gco2cl(o);
  256. g->gray = cl->c.gclist;
  257. traverseclosure(g, cl);
  258. return (cl->c.isC) ? sizeCclosure(cl->c.nupvalues) :
  259. sizeLclosure(cl->l.nupvalues);
  260. }
  261. case LUA_TTHREAD: {
  262. lua_State *th = gco2th(o);
  263. g->gray = th->gclist;
  264. th->gclist = g->grayagain;
  265. g->grayagain = o;
  266. black2gray(o);
  267. traversestack(g, th);
  268. return sizeof(lua_State) + sizeof(TValue) * th->stacksize +
  269. sizeof(CallInfo) * th->size_ci;
  270. }
  271. case LUA_TPROTO: {
  272. Proto *p = gco2p(o);
  273. g->gray = p->gclist;
  274. traverseproto(g, p);
  275. return sizeof(Proto) + sizeof(Proto *) * p->sizep +
  276. sizeof(TValue) * p->sizek +
  277. sizeof(LocVar) * p->sizelocvars +
  278. sizeof(TString *) * p->sizeupvalues +
  279. (proto_is_readonly(p) ? 0 : sizeof(Instruction) * p->sizecode +
  280. sizeof(int) * p->sizelineinfo);
  281. }
  282. default: lua_assert(0); return 0;
  283. }
  284. }
  285. static size_t propagateall (global_State *g) {
  286. size_t m = 0;
  287. while (g->gray) m += propagatemark(g);
  288. return m;
  289. }
  290. /*
  291. ** The next function tells whether a key or value can be cleared from
  292. ** a weak table. Non-collectable objects are never removed from weak
  293. ** tables. Strings behave as `values', so are never removed too. for
  294. ** other objects: if really collected, cannot keep them; for userdata
  295. ** being finalized, keep them in keys, but not in values
  296. */
  297. static int iscleared (const TValue *o, int iskey) {
  298. if (!iscollectable(o)) return 0;
  299. if (ttisstring(o)) {
  300. stringmark(rawtsvalue(o)); /* strings are `values', so are never weak */
  301. return 0;
  302. }
  303. return iswhite(gcvalue(o)) ||
  304. (ttisuserdata(o) && (!iskey && isfinalized(uvalue(o))));
  305. }
  306. /*
  307. ** clear collected entries from weaktables
  308. */
  309. static void cleartable (GCObject *l) {
  310. while (l) {
  311. Table *h = gco2h(l);
  312. int i = h->sizearray;
  313. lua_assert(testbit(h->marked, VALUEWEAKBIT) ||
  314. testbit(h->marked, KEYWEAKBIT));
  315. if (testbit(h->marked, VALUEWEAKBIT)) {
  316. while (i--) {
  317. TValue *o = &h->array[i];
  318. if (iscleared(o, 0)) /* value was collected? */
  319. setnilvalue(o); /* remove value */
  320. }
  321. }
  322. i = sizenode(h);
  323. while (i--) {
  324. Node *n = gnode(h, i);
  325. if (!ttisnil(gval(n)) && /* non-empty entry? */
  326. (iscleared(key2tval(n), 1) || iscleared(gval(n), 0))) {
  327. setnilvalue(gval(n)); /* remove value ... */
  328. removeentry(n); /* remove entry from table */
  329. }
  330. }
  331. l = h->gclist;
  332. }
  333. }
  334. static void freeobj (lua_State *L, GCObject *o) {
  335. switch (o->gch.tt) {
  336. case LUA_TPROTO: luaF_freeproto(L, gco2p(o)); break;
  337. case LUA_TFUNCTION: luaF_freeclosure(L, gco2cl(o)); break;
  338. case LUA_TUPVAL: luaF_freeupval(L, gco2uv(o)); break;
  339. case LUA_TTABLE: luaH_free(L, gco2h(o)); break;
  340. case LUA_TTHREAD: {
  341. lua_assert(gco2th(o) != L && gco2th(o) != G(L)->mainthread);
  342. luaE_freethread(L, gco2th(o));
  343. break;
  344. }
  345. case LUA_TSTRING: {
  346. G(L)->strt.nuse--;
  347. luaM_freemem(L, o, sizestring(gco2ts(o)));
  348. break;
  349. }
  350. case LUA_TUSERDATA: {
  351. luaM_freemem(L, o, sizeudata(gco2u(o)));
  352. break;
  353. }
  354. default: lua_assert(0);
  355. }
  356. }
  357. #define sweepwholelist(L,p) sweeplist(L,p,MAX_LUMEM)
  358. static GCObject **sweeplist (lua_State *L, GCObject **p, lu_mem count) {
  359. GCObject *curr;
  360. global_State *g = G(L);
  361. int deadmask = otherwhite(g);
  362. while ((curr = *p) != NULL && count-- > 0) {
  363. if (curr->gch.tt == LUA_TTHREAD) /* sweep open upvalues of each thread */
  364. sweepwholelist(L, &gco2th(curr)->openupval);
  365. if ((curr->gch.marked ^ WHITEBITS) & deadmask) { /* not dead? */
  366. lua_assert(!isdead(g, curr) || testbit(curr->gch.marked, FIXEDBIT));
  367. makewhite(g, curr); /* make it white (for next cycle) */
  368. p = &curr->gch.next;
  369. }
  370. else { /* must erase `curr' */
  371. lua_assert(isdead(g, curr) || deadmask == bitmask(SFIXEDBIT));
  372. *p = curr->gch.next;
  373. freeobj(L, curr);
  374. }
  375. }
  376. return p;
  377. }
  378. static void checkSizes (lua_State *L) {
  379. global_State *g = G(L);
  380. /* check size of string hash */
  381. if (g->strt.nuse < cast(lu_int32, g->strt.size/4) &&
  382. g->strt.size > MINSTRTABSIZE*2)
  383. luaS_resize(L, g->strt.size/2); /* table is too big */
  384. /* it is not safe to re-size the buffer if it is in use. */
  385. if (luaZ_bufflen(&g->buff) > 0) return;
  386. /* check size of buffer */
  387. if (luaZ_sizebuffer(&g->buff) > LUA_MINBUFFER*2) { /* buffer too big? */
  388. size_t newsize = luaZ_sizebuffer(&g->buff) / 2;
  389. luaZ_resizebuffer(L, &g->buff, newsize);
  390. }
  391. }
  392. static void GCTM (lua_State *L) {
  393. global_State *g = G(L);
  394. GCObject *o = g->tmudata->gch.next; /* get first element */
  395. Udata *udata = rawgco2u(o);
  396. const TValue *tm;
  397. /* remove udata from `tmudata' */
  398. if (o == g->tmudata) /* last element? */
  399. g->tmudata = NULL;
  400. else
  401. g->tmudata->gch.next = udata->uv.next;
  402. udata->uv.next = g->mainthread->next; /* return it to `root' list */
  403. g->mainthread->next = o;
  404. makewhite(g, o);
  405. tm = fasttm(L, udata->uv.metatable, TM_GC);
  406. if (tm != NULL) {
  407. lu_byte oldah = L->allowhook;
  408. lu_mem oldt = g->GCthreshold;
  409. L->allowhook = 0; /* stop debug hooks during GC tag method */
  410. g->GCthreshold = 2*g->totalbytes; /* avoid GC steps */
  411. setobj2s(L, L->top, tm);
  412. setuvalue(L, L->top+1, udata);
  413. L->top += 2;
  414. luaD_call(L, L->top - 2, 0);
  415. L->allowhook = oldah; /* restore hooks */
  416. g->GCthreshold = oldt; /* restore threshold */
  417. }
  418. }
  419. /*
  420. ** Call all GC tag methods
  421. */
  422. void luaC_callGCTM (lua_State *L) {
  423. while (G(L)->tmudata)
  424. GCTM(L);
  425. }
  426. void luaC_freeall (lua_State *L) {
  427. global_State *g = G(L);
  428. int i;
  429. g->currentwhite = WHITEBITS | bitmask(SFIXEDBIT); /* mask to collect all elements */
  430. sweepwholelist(L, &g->rootgc);
  431. for (i = 0; i < g->strt.size; i++) /* free all string lists */
  432. sweepwholelist(L, &g->strt.hash[i]);
  433. }
  434. static void markmt (global_State *g) {
  435. int i;
  436. for (i=0; i<NUM_TAGS; i++)
  437. if (g->mt[i] && !luaR_isrotable(g->mt[i])) markobject(g, g->mt[i]);
  438. }
  439. /* mark root set */
  440. static void markroot (lua_State *L) {
  441. global_State *g = G(L);
  442. g->gray = NULL;
  443. g->grayagain = NULL;
  444. g->weak = NULL;
  445. markobject(g, g->mainthread);
  446. /* make global table be traversed before main stack */
  447. markvalue(g, gt(g->mainthread));
  448. markvalue(g, registry(L));
  449. markmt(g);
  450. g->gcstate = GCSpropagate;
  451. }
  452. static void remarkupvals (global_State *g) {
  453. UpVal *uv;
  454. for (uv = g->uvhead.u.l.next; uv != &g->uvhead; uv = uv->u.l.next) {
  455. lua_assert(uv->u.l.next->u.l.prev == uv && uv->u.l.prev->u.l.next == uv);
  456. if (isgray(obj2gco(uv)))
  457. markvalue(g, uv->v);
  458. }
  459. }
  460. static void atomic (lua_State *L) {
  461. global_State *g = G(L);
  462. size_t udsize; /* total size of userdata to be finalized */
  463. /* remark occasional upvalues of (maybe) dead threads */
  464. remarkupvals(g);
  465. /* traverse objects cautch by write barrier and by 'remarkupvals' */
  466. propagateall(g);
  467. /* remark weak tables */
  468. g->gray = g->weak;
  469. g->weak = NULL;
  470. lua_assert(!iswhite(obj2gco(g->mainthread)));
  471. markobject(g, L); /* mark running thread */
  472. markmt(g); /* mark basic metatables (again) */
  473. propagateall(g);
  474. /* remark gray again */
  475. g->gray = g->grayagain;
  476. g->grayagain = NULL;
  477. propagateall(g);
  478. udsize = luaC_separateudata(L, 0); /* separate userdata to be finalized */
  479. marktmu(g); /* mark `preserved' userdata */
  480. udsize += propagateall(g); /* remark, to propagate `preserveness' */
  481. cleartable(g->weak); /* remove collected objects from weak tables */
  482. /* flip current white */
  483. g->currentwhite = cast_byte(otherwhite(g));
  484. g->sweepstrgc = 0;
  485. g->sweepgc = &g->rootgc;
  486. g->gcstate = GCSsweepstring;
  487. g->estimate = g->totalbytes - udsize; /* first estimate */
  488. }
  489. static void sweepstrstep (global_State *g, lua_State *L) {
  490. lu_mem old = g->totalbytes;
  491. sweepwholelist(L, &g->strt.hash[g->sweepstrgc++]);
  492. if (g->sweepstrgc >= g->strt.size) /* nothing more to sweep? */
  493. g->gcstate = GCSsweep; /* end sweep-string phase */
  494. lua_assert(old >= g->totalbytes);
  495. g->estimate -= old - g->totalbytes;
  496. }
  497. static l_mem singlestep (lua_State *L) {
  498. global_State *g = G(L);
  499. /*lua_checkmemory(L);*/
  500. switch (g->gcstate) {
  501. case GCSpause: {
  502. markroot(L); /* start a new collection */
  503. return 0;
  504. }
  505. case GCSpropagate: {
  506. if (g->gray)
  507. return propagatemark(g);
  508. else { /* no more `gray' objects */
  509. atomic(L); /* finish mark phase */
  510. return 0;
  511. }
  512. }
  513. case GCSsweepstring: {
  514. sweepstrstep(g, L);
  515. return GCSWEEPCOST;
  516. }
  517. case GCSsweep: {
  518. lu_mem old = g->totalbytes;
  519. g->sweepgc = sweeplist(L, g->sweepgc, GCSWEEPMAX);
  520. if (*g->sweepgc == NULL) { /* nothing more to sweep? */
  521. checkSizes(L);
  522. g->gcstate = GCSfinalize; /* end sweep phase */
  523. }
  524. lua_assert(old >= g->totalbytes);
  525. g->estimate -= old - g->totalbytes;
  526. return GCSWEEPMAX*GCSWEEPCOST;
  527. }
  528. case GCSfinalize: {
  529. if (g->tmudata) {
  530. GCTM(L);
  531. if (g->estimate > GCFINALIZECOST)
  532. g->estimate -= GCFINALIZECOST;
  533. return GCFINALIZECOST;
  534. }
  535. else {
  536. g->gcstate = GCSpause; /* end collection */
  537. g->gcdept = 0;
  538. return 0;
  539. }
  540. }
  541. default: lua_assert(0); return 0;
  542. }
  543. }
  544. void luaC_step (lua_State *L) {
  545. global_State *g = G(L);
  546. if(is_block_gc(L)) return;
  547. set_block_gc(L);
  548. l_mem lim = (GCSTEPSIZE/100) * g->gcstepmul;
  549. if (lim == 0)
  550. lim = (MAX_LUMEM-1)/2; /* no limit */
  551. g->gcdept += g->totalbytes - g->GCthreshold;
  552. if (g->estimate > g->totalbytes)
  553. g->estimate = g->totalbytes;
  554. do {
  555. lim -= singlestep(L);
  556. if (g->gcstate == GCSpause)
  557. break;
  558. } while (lim > 0);
  559. if (g->gcstate != GCSpause) {
  560. if (g->gcdept < GCSTEPSIZE)
  561. g->GCthreshold = g->totalbytes + GCSTEPSIZE; /* - lim/g->gcstepmul;*/
  562. else {
  563. g->gcdept -= GCSTEPSIZE;
  564. g->GCthreshold = g->totalbytes;
  565. }
  566. }
  567. else {
  568. lua_assert(g->totalbytes >= g->estimate);
  569. setthreshold(g);
  570. }
  571. unset_block_gc(L);
  572. }
  573. int luaC_sweepstrgc (lua_State *L) {
  574. global_State *g = G(L);
  575. if (g->gcstate == GCSsweepstring) {
  576. sweepstrstep(g, L);
  577. return (g->gcstate == GCSsweepstring) ? 1 : 0;
  578. }
  579. return 0;
  580. }
  581. void luaC_fullgc (lua_State *L) {
  582. global_State *g = G(L);
  583. if(is_block_gc(L)) return;
  584. set_block_gc(L);
  585. if (g->gcstate <= GCSpropagate) {
  586. /* reset sweep marks to sweep all elements (returning them to white) */
  587. g->sweepstrgc = 0;
  588. g->sweepgc = &g->rootgc;
  589. /* reset other collector lists */
  590. g->gray = NULL;
  591. g->grayagain = NULL;
  592. g->weak = NULL;
  593. g->gcstate = GCSsweepstring;
  594. }
  595. lua_assert(g->gcstate != GCSpause && g->gcstate != GCSpropagate);
  596. /* finish any pending sweep phase */
  597. while (g->gcstate != GCSfinalize) {
  598. lua_assert(g->gcstate == GCSsweepstring || g->gcstate == GCSsweep);
  599. singlestep(L);
  600. }
  601. markroot(L);
  602. while (g->gcstate != GCSpause) {
  603. singlestep(L);
  604. }
  605. setthreshold(g);
  606. unset_block_gc(L);
  607. }
  608. void luaC_barrierf (lua_State *L, GCObject *o, GCObject *v) {
  609. global_State *g = G(L);
  610. lua_assert(isblack(o) && iswhite(v) && !isdead(g, v) && !isdead(g, o));
  611. lua_assert(g->gcstate != GCSfinalize && g->gcstate != GCSpause);
  612. lua_assert(ttype(&o->gch) != LUA_TTABLE);
  613. /* must keep invariant? */
  614. if (g->gcstate == GCSpropagate)
  615. reallymarkobject(g, v); /* restore invariant */
  616. else /* don't mind */
  617. makewhite(g, o); /* mark as white just to avoid other barriers */
  618. }
  619. void luaC_barrierback (lua_State *L, Table *t) {
  620. global_State *g = G(L);
  621. GCObject *o = obj2gco(t);
  622. lua_assert(isblack(o) && !isdead(g, o));
  623. lua_assert(g->gcstate != GCSfinalize && g->gcstate != GCSpause);
  624. black2gray(o); /* make table gray (again) */
  625. t->gclist = g->grayagain;
  626. g->grayagain = o;
  627. }
  628. void luaC_marknew (lua_State *L, GCObject *o) {
  629. global_State *g = G(L);
  630. o->gch.marked = luaC_white(g);
  631. if (g->gcstate == GCSpropagate)
  632. reallymarkobject(g, o); /* mark new objects as gray during propagate state. */
  633. }
  634. void luaC_link (lua_State *L, GCObject *o, lu_byte tt) {
  635. global_State *g = G(L);
  636. o->gch.next = g->rootgc;
  637. g->rootgc = o;
  638. o->gch.marked = luaC_white(g);
  639. o->gch.tt = tt;
  640. }
  641. void luaC_linkupval (lua_State *L, UpVal *uv) {
  642. global_State *g = G(L);
  643. GCObject *o = obj2gco(uv);
  644. o->gch.next = g->rootgc; /* link upvalue into `rootgc' list */
  645. g->rootgc = o;
  646. if (isgray(o)) {
  647. if (g->gcstate == GCSpropagate) {
  648. gray2black(o); /* closed upvalues need barrier */
  649. luaC_barrier(L, uv, uv->v);
  650. }
  651. else { /* sweep phase: sweep it (turning it into white) */
  652. makewhite(g, o);
  653. lua_assert(g->gcstate != GCSfinalize && g->gcstate != GCSpause);
  654. }
  655. }
  656. }