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