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