2812
+ − 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
+ − 7 #include <string.h>
+ − 8
+ − 9 #define lgc_c
+ − 10 #define LUA_CORE
+ − 11
+ − 12 #include "lua.h"
+ − 13
+ − 14 #include "ldebug.h"
+ − 15 #include "ldo.h"
+ − 16 #include "lfunc.h"
+ − 17 #include "lgc.h"
+ − 18 #include "lmem.h"
+ − 19 #include "lobject.h"
+ − 20 #include "lstate.h"
+ − 21 #include "lstring.h"
+ − 22 #include "ltable.h"
+ − 23 #include "ltm.h"
+ − 24
+ − 25
+ − 26 #define GCSTEPSIZE 1024u
+ − 27 #define GCSWEEPMAX 40
+ − 28 #define GCSWEEPCOST 10
+ − 29 #define GCFINALIZECOST 100
+ − 30
+ − 31
+ − 32 #define maskmarks cast_byte(~(bitmask(BLACKBIT)|WHITEBITS))
+ − 33
+ − 34 #define makewhite(g,x) \
+ − 35 ((x)->gch.marked = cast_byte(((x)->gch.marked & maskmarks) | luaC_white(g)))
+ − 36
+ − 37 #define white2gray(x) reset2bits((x)->gch.marked, WHITE0BIT, WHITE1BIT)
+ − 38 #define black2gray(x) resetbit((x)->gch.marked, BLACKBIT)
+ − 39
+ − 40 #define stringmark(s) reset2bits((s)->tsv.marked, WHITE0BIT, WHITE1BIT)
+ − 41
+ − 42
+ − 43 #define isfinalized(u) testbit((u)->marked, FINALIZEDBIT)
+ − 44 #define markfinalized(u) l_setbit((u)->marked, FINALIZEDBIT)
+ − 45
+ − 46
+ − 47 #define KEYWEAK bitmask(KEYWEAKBIT)
+ − 48 #define VALUEWEAK bitmask(VALUEWEAKBIT)
+ − 49
+ − 50
+ − 51
+ − 52 #define markvalue(g,o) { checkconsistency(o); \
+ − 53 if (iscollectable(o) && iswhite(gcvalue(o))) reallymarkobject(g,gcvalue(o)); }
+ − 54
+ − 55 #define markobject(g,t) { if (iswhite(obj2gco(t))) \
+ − 56 reallymarkobject(g, obj2gco(t)); }
+ − 57
+ − 58
+ − 59 #define setthreshold(g) (g->GCthreshold = (g->estimate/100) * g->gcpause)
+ − 60
+ − 61
+ − 62 static void removeentry (Node *n) {
+ − 63 lua_assert(ttisnil(gval(n)));
+ − 64 if (iscollectable(gkey(n)))
+ − 65 setttype(gkey(n), LUA_TDEADKEY); /* dead key; remove it */
+ − 66 }
+ − 67
+ − 68
+ − 69 static void reallymarkobject (global_State *g, GCObject *o) {
+ − 70 lua_assert(iswhite(o) && !isdead(g, o));
+ − 71 white2gray(o);
+ − 72 switch (o->gch.tt) {
+ − 73 case LUA_TSTRING: {
+ − 74 return;
+ − 75 }
+ − 76 case LUA_TUSERDATA: {
+ − 77 Table *mt = gco2u(o)->metatable;
+ − 78 gray2black(o); /* udata are never gray */
+ − 79 if (mt) markobject(g, mt);
+ − 80 markobject(g, gco2u(o)->env);
+ − 81 return;
+ − 82 }
+ − 83 case LUA_TUPVAL: {
+ − 84 UpVal *uv = gco2uv(o);
+ − 85 markvalue(g, uv->v);
+ − 86 if (uv->v == &uv->u.value) /* closed? */
+ − 87 gray2black(o); /* open upvalues are never black */
+ − 88 return;
+ − 89 }
+ − 90 case LUA_TFUNCTION: {
+ − 91 gco2cl(o)->c.gclist = g->gray;
+ − 92 g->gray = o;
+ − 93 break;
+ − 94 }
+ − 95 case LUA_TTABLE: {
+ − 96 gco2h(o)->gclist = g->gray;
+ − 97 g->gray = o;
+ − 98 break;
+ − 99 }
+ − 100 case LUA_TTHREAD: {
+ − 101 gco2th(o)->gclist = g->gray;
+ − 102 g->gray = o;
+ − 103 break;
+ − 104 }
+ − 105 case LUA_TPROTO: {
+ − 106 gco2p(o)->gclist = g->gray;
+ − 107 g->gray = o;
+ − 108 break;
+ − 109 }
+ − 110 default: lua_assert(0);
+ − 111 }
+ − 112 }
+ − 113
+ − 114
+ − 115 static void marktmu (global_State *g) {
+ − 116 GCObject *u = g->tmudata;
+ − 117 if (u) {
+ − 118 do {
+ − 119 u = u->gch.next;
+ − 120 makewhite(g, u); /* may be marked, if left from previous GC */
+ − 121 reallymarkobject(g, u);
+ − 122 } while (u != g->tmudata);
+ − 123 }
+ − 124 }
+ − 125
+ − 126
+ − 127 /* move `dead' udata that need finalization to list `tmudata' */
+ − 128 size_t luaC_separateudata (lua_State *L, int all) {
+ − 129 global_State *g = G(L);
+ − 130 size_t deadmem = 0;
+ − 131 GCObject **p = &g->mainthread->next;
+ − 132 GCObject *curr;
+ − 133 while ((curr = *p) != NULL) {
+ − 134 if (!(iswhite(curr) || all) || isfinalized(gco2u(curr)))
+ − 135 p = &curr->gch.next; /* don't bother with them */
+ − 136 else if (fasttm(L, gco2u(curr)->metatable, TM_GC) == NULL) {
+ − 137 markfinalized(gco2u(curr)); /* don't need finalization */
+ − 138 p = &curr->gch.next;
+ − 139 }
+ − 140 else { /* must call its gc method */
+ − 141 deadmem += sizeudata(gco2u(curr));
+ − 142 markfinalized(gco2u(curr));
+ − 143 *p = curr->gch.next;
+ − 144 /* link `curr' at the end of `tmudata' list */
+ − 145 if (g->tmudata == NULL) /* list is empty? */
+ − 146 g->tmudata = curr->gch.next = curr; /* creates a circular list */
+ − 147 else {
+ − 148 curr->gch.next = g->tmudata->gch.next;
+ − 149 g->tmudata->gch.next = curr;
+ − 150 g->tmudata = curr;
+ − 151 }
+ − 152 }
+ − 153 }
+ − 154 return deadmem;
+ − 155 }
+ − 156
+ − 157
+ − 158 static int traversetable (global_State *g, Table *h) {
+ − 159 int i;
+ − 160 int weakkey = 0;
+ − 161 int weakvalue = 0;
+ − 162 const TValue *mode;
+ − 163 if (h->metatable)
+ − 164 markobject(g, h->metatable);
+ − 165 mode = gfasttm(g, h->metatable, TM_MODE);
+ − 166 if (mode && ttisstring(mode)) { /* is there a weak mode? */
+ − 167 weakkey = (strchr(svalue(mode), 'k') != NULL);
+ − 168 weakvalue = (strchr(svalue(mode), 'v') != NULL);
+ − 169 if (weakkey || weakvalue) { /* is really weak? */
+ − 170 h->marked &= ~(KEYWEAK | VALUEWEAK); /* clear bits */
+ − 171 h->marked |= cast_byte((weakkey << KEYWEAKBIT) |
+ − 172 (weakvalue << VALUEWEAKBIT));
+ − 173 h->gclist = g->weak; /* must be cleared after GC, ... */
+ − 174 g->weak = obj2gco(h); /* ... so put in the appropriate list */
+ − 175 }
+ − 176 }
+ − 177 if (weakkey && weakvalue) return 1;
+ − 178 if (!weakvalue) {
+ − 179 i = h->sizearray;
+ − 180 while (i--)
+ − 181 markvalue(g, &h->array[i]);
+ − 182 }
+ − 183 i = sizenode(h);
+ − 184 while (i--) {
+ − 185 Node *n = gnode(h, i);
+ − 186 lua_assert(ttype(gkey(n)) != LUA_TDEADKEY || ttisnil(gval(n)));
+ − 187 if (ttisnil(gval(n)))
+ − 188 removeentry(n); /* remove empty entries */
+ − 189 else {
+ − 190 lua_assert(!ttisnil(gkey(n)));
+ − 191 if (!weakkey) markvalue(g, gkey(n));
+ − 192 if (!weakvalue) markvalue(g, gval(n));
+ − 193 }
+ − 194 }
+ − 195 return weakkey || weakvalue;
+ − 196 }
+ − 197
+ − 198
+ − 199 /*
+ − 200 ** All marks are conditional because a GC may happen while the
+ − 201 ** prototype is still being created
+ − 202 */
+ − 203 static void traverseproto (global_State *g, Proto *f) {
+ − 204 int i;
+ − 205 if (f->source) stringmark(f->source);
+ − 206 for (i=0; i<f->sizek; i++) /* mark literals */
+ − 207 markvalue(g, &f->k[i]);
+ − 208 for (i=0; i<f->sizeupvalues; i++) { /* mark upvalue names */
+ − 209 if (f->upvalues[i])
+ − 210 stringmark(f->upvalues[i]);
+ − 211 }
+ − 212 for (i=0; i<f->sizep; i++) { /* mark nested protos */
+ − 213 if (f->p[i])
+ − 214 markobject(g, f->p[i]);
+ − 215 }
+ − 216 for (i=0; i<f->sizelocvars; i++) { /* mark local-variable names */
+ − 217 if (f->locvars[i].varname)
+ − 218 stringmark(f->locvars[i].varname);
+ − 219 }
+ − 220 }
+ − 221
+ − 222
+ − 223
+ − 224 static void traverseclosure (global_State *g, Closure *cl) {
+ − 225 markobject(g, cl->c.env);
+ − 226 if (cl->c.isC) {
+ − 227 int i;
+ − 228 for (i=0; i<cl->c.nupvalues; i++) /* mark its upvalues */
+ − 229 markvalue(g, &cl->c.upvalue[i]);
+ − 230 }
+ − 231 else {
+ − 232 int i;
+ − 233 lua_assert(cl->l.nupvalues == cl->l.p->nups);
+ − 234 markobject(g, cl->l.p);
+ − 235 for (i=0; i<cl->l.nupvalues; i++) /* mark its upvalues */
+ − 236 markobject(g, cl->l.upvals[i]);
+ − 237 }
+ − 238 }
+ − 239
+ − 240
+ − 241 static void checkstacksizes (lua_State *L, StkId max) {
+ − 242 int ci_used = cast_int(L->ci - L->base_ci); /* number of `ci' in use */
+ − 243 int s_used = cast_int(max - L->stack); /* part of stack in use */
+ − 244 if (L->size_ci > LUAI_MAXCALLS) /* handling overflow? */
+ − 245 return; /* do not touch the stacks */
+ − 246 if (4*ci_used < L->size_ci && 2*BASIC_CI_SIZE < L->size_ci)
+ − 247 luaD_reallocCI(L, L->size_ci/2); /* still big enough... */
+ − 248 condhardstacktests(luaD_reallocCI(L, ci_used + 1));
+ − 249 if (4*s_used < L->stacksize &&
+ − 250 2*(BASIC_STACK_SIZE+EXTRA_STACK) < L->stacksize)
+ − 251 luaD_reallocstack(L, L->stacksize/2); /* still big enough... */
+ − 252 condhardstacktests(luaD_reallocstack(L, s_used));
+ − 253 }
+ − 254
+ − 255
+ − 256 static void traversestack (global_State *g, lua_State *l) {
+ − 257 StkId o, lim;
+ − 258 CallInfo *ci;
+ − 259 markvalue(g, gt(l));
+ − 260 lim = l->top;
+ − 261 for (ci = l->base_ci; ci <= l->ci; ci++) {
+ − 262 lua_assert(ci->top <= l->stack_last);
+ − 263 if (lim < ci->top) lim = ci->top;
+ − 264 }
+ − 265 for (o = l->stack; o < l->top; o++)
+ − 266 markvalue(g, o);
+ − 267 for (; o <= lim; o++)
+ − 268 setnilvalue(o);
+ − 269 checkstacksizes(l, lim);
+ − 270 }
+ − 271
+ − 272
+ − 273 /*
+ − 274 ** traverse one gray object, turning it to black.
+ − 275 ** Returns `quantity' traversed.
+ − 276 */
+ − 277 static l_mem propagatemark (global_State *g) {
+ − 278 GCObject *o = g->gray;
+ − 279 lua_assert(isgray(o));
+ − 280 gray2black(o);
+ − 281 switch (o->gch.tt) {
+ − 282 case LUA_TTABLE: {
+ − 283 Table *h = gco2h(o);
+ − 284 g->gray = h->gclist;
+ − 285 if (traversetable(g, h)) /* table is weak? */
+ − 286 black2gray(o); /* keep it gray */
+ − 287 return sizeof(Table) + sizeof(TValue) * h->sizearray +
+ − 288 sizeof(Node) * sizenode(h);
+ − 289 }
+ − 290 case LUA_TFUNCTION: {
+ − 291 Closure *cl = gco2cl(o);
+ − 292 g->gray = cl->c.gclist;
+ − 293 traverseclosure(g, cl);
+ − 294 return (cl->c.isC) ? sizeCclosure(cl->c.nupvalues) :
+ − 295 sizeLclosure(cl->l.nupvalues);
+ − 296 }
+ − 297 case LUA_TTHREAD: {
+ − 298 lua_State *th = gco2th(o);
+ − 299 g->gray = th->gclist;
+ − 300 th->gclist = g->grayagain;
+ − 301 g->grayagain = o;
+ − 302 black2gray(o);
+ − 303 traversestack(g, th);
+ − 304 return sizeof(lua_State) + sizeof(TValue) * th->stacksize +
+ − 305 sizeof(CallInfo) * th->size_ci;
+ − 306 }
+ − 307 case LUA_TPROTO: {
+ − 308 Proto *p = gco2p(o);
+ − 309 g->gray = p->gclist;
+ − 310 traverseproto(g, p);
+ − 311 return sizeof(Proto) + sizeof(Instruction) * p->sizecode +
+ − 312 sizeof(Proto *) * p->sizep +
3697
+ − 313 sizeof(TValue) * p->sizek +
2812
+ − 314 sizeof(int) * p->sizelineinfo +
+ − 315 sizeof(LocVar) * p->sizelocvars +
+ − 316 sizeof(TString *) * p->sizeupvalues;
+ − 317 }
+ − 318 default: lua_assert(0); return 0;
+ − 319 }
+ − 320 }
+ − 321
+ − 322
+ − 323 static size_t propagateall (global_State *g) {
+ − 324 size_t m = 0;
+ − 325 while (g->gray) m += propagatemark(g);
+ − 326 return m;
+ − 327 }
+ − 328
+ − 329
+ − 330 /*
+ − 331 ** The next function tells whether a key or value can be cleared from
+ − 332 ** a weak table. Non-collectable objects are never removed from weak
+ − 333 ** tables. Strings behave as `values', so are never removed too. for
+ − 334 ** other objects: if really collected, cannot keep them; for userdata
+ − 335 ** being finalized, keep them in keys, but not in values
+ − 336 */
+ − 337 static int iscleared (const TValue *o, int iskey) {
+ − 338 if (!iscollectable(o)) return 0;
+ − 339 if (ttisstring(o)) {
+ − 340 stringmark(rawtsvalue(o)); /* strings are `values', so are never weak */
+ − 341 return 0;
+ − 342 }
+ − 343 return iswhite(gcvalue(o)) ||
+ − 344 (ttisuserdata(o) && (!iskey && isfinalized(uvalue(o))));
+ − 345 }
+ − 346
+ − 347
+ − 348 /*
+ − 349 ** clear collected entries from weaktables
+ − 350 */
+ − 351 static void cleartable (GCObject *l) {
+ − 352 while (l) {
+ − 353 Table *h = gco2h(l);
+ − 354 int i = h->sizearray;
+ − 355 lua_assert(testbit(h->marked, VALUEWEAKBIT) ||
+ − 356 testbit(h->marked, KEYWEAKBIT));
+ − 357 if (testbit(h->marked, VALUEWEAKBIT)) {
+ − 358 while (i--) {
+ − 359 TValue *o = &h->array[i];
+ − 360 if (iscleared(o, 0)) /* value was collected? */
+ − 361 setnilvalue(o); /* remove value */
+ − 362 }
+ − 363 }
+ − 364 i = sizenode(h);
+ − 365 while (i--) {
+ − 366 Node *n = gnode(h, i);
+ − 367 if (!ttisnil(gval(n)) && /* non-empty entry? */
+ − 368 (iscleared(key2tval(n), 1) || iscleared(gval(n), 0))) {
+ − 369 setnilvalue(gval(n)); /* remove value ... */
+ − 370 removeentry(n); /* remove entry from table */
+ − 371 }
+ − 372 }
+ − 373 l = h->gclist;
+ − 374 }
+ − 375 }
+ − 376
+ − 377
+ − 378 static void freeobj (lua_State *L, GCObject *o) {
+ − 379 switch (o->gch.tt) {
+ − 380 case LUA_TPROTO: luaF_freeproto(L, gco2p(o)); break;
+ − 381 case LUA_TFUNCTION: luaF_freeclosure(L, gco2cl(o)); break;
+ − 382 case LUA_TUPVAL: luaF_freeupval(L, gco2uv(o)); break;
+ − 383 case LUA_TTABLE: luaH_free(L, gco2h(o)); break;
+ − 384 case LUA_TTHREAD: {
+ − 385 lua_assert(gco2th(o) != L && gco2th(o) != G(L)->mainthread);
+ − 386 luaE_freethread(L, gco2th(o));
+ − 387 break;
+ − 388 }
+ − 389 case LUA_TSTRING: {
+ − 390 G(L)->strt.nuse--;
+ − 391 luaM_freemem(L, o, sizestring(gco2ts(o)));
+ − 392 break;
+ − 393 }
+ − 394 case LUA_TUSERDATA: {
+ − 395 luaM_freemem(L, o, sizeudata(gco2u(o)));
+ − 396 break;
+ − 397 }
+ − 398 default: lua_assert(0);
+ − 399 }
+ − 400 }
+ − 401
+ − 402
+ − 403
+ − 404 #define sweepwholelist(L,p) sweeplist(L,p,MAX_LUMEM)
+ − 405
+ − 406
+ − 407 static GCObject **sweeplist (lua_State *L, GCObject **p, lu_mem count) {
+ − 408 GCObject *curr;
+ − 409 global_State *g = G(L);
+ − 410 int deadmask = otherwhite(g);
+ − 411 while ((curr = *p) != NULL && count-- > 0) {
+ − 412 if (curr->gch.tt == LUA_TTHREAD) /* sweep open upvalues of each thread */
+ − 413 sweepwholelist(L, &gco2th(curr)->openupval);
+ − 414 if ((curr->gch.marked ^ WHITEBITS) & deadmask) { /* not dead? */
+ − 415 lua_assert(!isdead(g, curr) || testbit(curr->gch.marked, FIXEDBIT));
+ − 416 makewhite(g, curr); /* make it white (for next cycle) */
+ − 417 p = &curr->gch.next;
+ − 418 }
+ − 419 else { /* must erase `curr' */
+ − 420 lua_assert(isdead(g, curr) || deadmask == bitmask(SFIXEDBIT));
+ − 421 *p = curr->gch.next;
+ − 422 if (curr == g->rootgc) /* is the first element of the list? */
+ − 423 g->rootgc = curr->gch.next; /* adjust first */
+ − 424 freeobj(L, curr);
+ − 425 }
+ − 426 }
+ − 427 return p;
+ − 428 }
+ − 429
+ − 430
+ − 431 static void checkSizes (lua_State *L) {
+ − 432 global_State *g = G(L);
+ − 433 /* check size of string hash */
+ − 434 if (g->strt.nuse < cast(lu_int32, g->strt.size/4) &&
+ − 435 g->strt.size > MINSTRTABSIZE*2)
+ − 436 luaS_resize(L, g->strt.size/2); /* table is too big */
+ − 437 /* check size of buffer */
+ − 438 if (luaZ_sizebuffer(&g->buff) > LUA_MINBUFFER*2) { /* buffer too big? */
+ − 439 size_t newsize = luaZ_sizebuffer(&g->buff) / 2;
+ − 440 luaZ_resizebuffer(L, &g->buff, newsize);
+ − 441 }
+ − 442 }
+ − 443
+ − 444
+ − 445 static void GCTM (lua_State *L) {
+ − 446 global_State *g = G(L);
+ − 447 GCObject *o = g->tmudata->gch.next; /* get first element */
+ − 448 Udata *udata = rawgco2u(o);
+ − 449 const TValue *tm;
+ − 450 /* remove udata from `tmudata' */
+ − 451 if (o == g->tmudata) /* last element? */
+ − 452 g->tmudata = NULL;
+ − 453 else
+ − 454 g->tmudata->gch.next = udata->uv.next;
+ − 455 udata->uv.next = g->mainthread->next; /* return it to `root' list */
+ − 456 g->mainthread->next = o;
+ − 457 makewhite(g, o);
+ − 458 tm = fasttm(L, udata->uv.metatable, TM_GC);
+ − 459 if (tm != NULL) {
+ − 460 lu_byte oldah = L->allowhook;
+ − 461 lu_mem oldt = g->GCthreshold;
+ − 462 L->allowhook = 0; /* stop debug hooks during GC tag method */
+ − 463 g->GCthreshold = 2*g->totalbytes; /* avoid GC steps */
+ − 464 setobj2s(L, L->top, tm);
+ − 465 setuvalue(L, L->top+1, udata);
+ − 466 L->top += 2;
+ − 467 luaD_call(L, L->top - 2, 0);
+ − 468 L->allowhook = oldah; /* restore hooks */
+ − 469 g->GCthreshold = oldt; /* restore threshold */
+ − 470 }
+ − 471 }
+ − 472
+ − 473
+ − 474 /*
+ − 475 ** Call all GC tag methods
+ − 476 */
+ − 477 void luaC_callGCTM (lua_State *L) {
+ − 478 while (G(L)->tmudata)
+ − 479 GCTM(L);
+ − 480 }
+ − 481
+ − 482
+ − 483 void luaC_freeall (lua_State *L) {
+ − 484 global_State *g = G(L);
+ − 485 int i;
+ − 486 g->currentwhite = WHITEBITS | bitmask(SFIXEDBIT); /* mask to collect all elements */
+ − 487 sweepwholelist(L, &g->rootgc);
+ − 488 for (i = 0; i < g->strt.size; i++) /* free all string lists */
+ − 489 sweepwholelist(L, &g->strt.hash[i]);
+ − 490 }
+ − 491
+ − 492
+ − 493 static void markmt (global_State *g) {
+ − 494 int i;
+ − 495 for (i=0; i<NUM_TAGS; i++)
+ − 496 if (g->mt[i]) markobject(g, g->mt[i]);
+ − 497 }
+ − 498
+ − 499
+ − 500 /* mark root set */
+ − 501 static void markroot (lua_State *L) {
+ − 502 global_State *g = G(L);
+ − 503 g->gray = NULL;
+ − 504 g->grayagain = NULL;
+ − 505 g->weak = NULL;
+ − 506 markobject(g, g->mainthread);
+ − 507 /* make global table be traversed before main stack */
+ − 508 markvalue(g, gt(g->mainthread));
+ − 509 markvalue(g, registry(L));
+ − 510 markmt(g);
+ − 511 g->gcstate = GCSpropagate;
+ − 512 }
+ − 513
+ − 514
+ − 515 static void remarkupvals (global_State *g) {
+ − 516 UpVal *uv;
+ − 517 for (uv = g->uvhead.u.l.next; uv != &g->uvhead; uv = uv->u.l.next) {
+ − 518 lua_assert(uv->u.l.next->u.l.prev == uv && uv->u.l.prev->u.l.next == uv);
+ − 519 if (isgray(obj2gco(uv)))
+ − 520 markvalue(g, uv->v);
+ − 521 }
+ − 522 }
+ − 523
+ − 524
+ − 525 static void atomic (lua_State *L) {
+ − 526 global_State *g = G(L);
+ − 527 size_t udsize; /* total size of userdata to be finalized */
+ − 528 /* remark occasional upvalues of (maybe) dead threads */
+ − 529 remarkupvals(g);
+ − 530 /* traverse objects cautch by write barrier and by 'remarkupvals' */
+ − 531 propagateall(g);
+ − 532 /* remark weak tables */
+ − 533 g->gray = g->weak;
+ − 534 g->weak = NULL;
+ − 535 lua_assert(!iswhite(obj2gco(g->mainthread)));
+ − 536 markobject(g, L); /* mark running thread */
+ − 537 markmt(g); /* mark basic metatables (again) */
+ − 538 propagateall(g);
+ − 539 /* remark gray again */
+ − 540 g->gray = g->grayagain;
+ − 541 g->grayagain = NULL;
+ − 542 propagateall(g);
+ − 543 udsize = luaC_separateudata(L, 0); /* separate userdata to be finalized */
+ − 544 marktmu(g); /* mark `preserved' userdata */
+ − 545 udsize += propagateall(g); /* remark, to propagate `preserveness' */
+ − 546 cleartable(g->weak); /* remove collected objects from weak tables */
+ − 547 /* flip current white */
+ − 548 g->currentwhite = cast_byte(otherwhite(g));
+ − 549 g->sweepstrgc = 0;
+ − 550 g->sweepgc = &g->rootgc;
+ − 551 g->gcstate = GCSsweepstring;
+ − 552 g->estimate = g->totalbytes - udsize; /* first estimate */
+ − 553 }
+ − 554
+ − 555
+ − 556 static l_mem singlestep (lua_State *L) {
+ − 557 global_State *g = G(L);
+ − 558 /*lua_checkmemory(L);*/
+ − 559 switch (g->gcstate) {
+ − 560 case GCSpause: {
+ − 561 markroot(L); /* start a new collection */
+ − 562 return 0;
+ − 563 }
+ − 564 case GCSpropagate: {
+ − 565 if (g->gray)
+ − 566 return propagatemark(g);
+ − 567 else { /* no more `gray' objects */
+ − 568 atomic(L); /* finish mark phase */
+ − 569 return 0;
+ − 570 }
+ − 571 }
+ − 572 case GCSsweepstring: {
+ − 573 lu_mem old = g->totalbytes;
+ − 574 sweepwholelist(L, &g->strt.hash[g->sweepstrgc++]);
+ − 575 if (g->sweepstrgc >= g->strt.size) /* nothing more to sweep? */
+ − 576 g->gcstate = GCSsweep; /* end sweep-string phase */
+ − 577 lua_assert(old >= g->totalbytes);
+ − 578 g->estimate -= old - g->totalbytes;
+ − 579 return GCSWEEPCOST;
+ − 580 }
+ − 581 case GCSsweep: {
+ − 582 lu_mem old = g->totalbytes;
+ − 583 g->sweepgc = sweeplist(L, g->sweepgc, GCSWEEPMAX);
+ − 584 if (*g->sweepgc == NULL) { /* nothing more to sweep? */
+ − 585 checkSizes(L);
+ − 586 g->gcstate = GCSfinalize; /* end sweep phase */
+ − 587 }
+ − 588 lua_assert(old >= g->totalbytes);
+ − 589 g->estimate -= old - g->totalbytes;
+ − 590 return GCSWEEPMAX*GCSWEEPCOST;
+ − 591 }
+ − 592 case GCSfinalize: {
+ − 593 if (g->tmudata) {
+ − 594 GCTM(L);
+ − 595 if (g->estimate > GCFINALIZECOST)
+ − 596 g->estimate -= GCFINALIZECOST;
+ − 597 return GCFINALIZECOST;
+ − 598 }
+ − 599 else {
+ − 600 g->gcstate = GCSpause; /* end collection */
+ − 601 g->gcdept = 0;
+ − 602 return 0;
+ − 603 }
+ − 604 }
+ − 605 default: lua_assert(0); return 0;
+ − 606 }
+ − 607 }
+ − 608
+ − 609
+ − 610 void luaC_step (lua_State *L) {
+ − 611 global_State *g = G(L);
+ − 612 l_mem lim = (GCSTEPSIZE/100) * g->gcstepmul;
+ − 613 if (lim == 0)
+ − 614 lim = (MAX_LUMEM-1)/2; /* no limit */
+ − 615 g->gcdept += g->totalbytes - g->GCthreshold;
+ − 616 do {
+ − 617 lim -= singlestep(L);
+ − 618 if (g->gcstate == GCSpause)
+ − 619 break;
+ − 620 } while (lim > 0);
+ − 621 if (g->gcstate != GCSpause) {
+ − 622 if (g->gcdept < GCSTEPSIZE)
+ − 623 g->GCthreshold = g->totalbytes + GCSTEPSIZE; /* - lim/g->gcstepmul;*/
+ − 624 else {
+ − 625 g->gcdept -= GCSTEPSIZE;
+ − 626 g->GCthreshold = g->totalbytes;
+ − 627 }
+ − 628 }
+ − 629 else {
+ − 630 lua_assert(g->totalbytes >= g->estimate);
+ − 631 setthreshold(g);
+ − 632 }
+ − 633 }
+ − 634
+ − 635
+ − 636 void luaC_fullgc (lua_State *L) {
+ − 637 global_State *g = G(L);
+ − 638 if (g->gcstate <= GCSpropagate) {
+ − 639 /* reset sweep marks to sweep all elements (returning them to white) */
+ − 640 g->sweepstrgc = 0;
+ − 641 g->sweepgc = &g->rootgc;
+ − 642 /* reset other collector lists */
+ − 643 g->gray = NULL;
+ − 644 g->grayagain = NULL;
+ − 645 g->weak = NULL;
+ − 646 g->gcstate = GCSsweepstring;
+ − 647 }
+ − 648 lua_assert(g->gcstate != GCSpause && g->gcstate != GCSpropagate);
+ − 649 /* finish any pending sweep phase */
+ − 650 while (g->gcstate != GCSfinalize) {
+ − 651 lua_assert(g->gcstate == GCSsweepstring || g->gcstate == GCSsweep);
+ − 652 singlestep(L);
+ − 653 }
+ − 654 markroot(L);
+ − 655 while (g->gcstate != GCSpause) {
+ − 656 singlestep(L);
+ − 657 }
+ − 658 setthreshold(g);
+ − 659 }
+ − 660
+ − 661
+ − 662 void luaC_barrierf (lua_State *L, GCObject *o, GCObject *v) {
+ − 663 global_State *g = G(L);
+ − 664 lua_assert(isblack(o) && iswhite(v) && !isdead(g, v) && !isdead(g, o));
+ − 665 lua_assert(g->gcstate != GCSfinalize && g->gcstate != GCSpause);
+ − 666 lua_assert(ttype(&o->gch) != LUA_TTABLE);
+ − 667 /* must keep invariant? */
+ − 668 if (g->gcstate == GCSpropagate)
+ − 669 reallymarkobject(g, v); /* restore invariant */
+ − 670 else /* don't mind */
+ − 671 makewhite(g, o); /* mark as white just to avoid other barriers */
+ − 672 }
+ − 673
+ − 674
+ − 675 void luaC_barrierback (lua_State *L, Table *t) {
+ − 676 global_State *g = G(L);
+ − 677 GCObject *o = obj2gco(t);
+ − 678 lua_assert(isblack(o) && !isdead(g, o));
+ − 679 lua_assert(g->gcstate != GCSfinalize && g->gcstate != GCSpause);
+ − 680 black2gray(o); /* make table gray (again) */
+ − 681 t->gclist = g->grayagain;
+ − 682 g->grayagain = o;
+ − 683 }
+ − 684
+ − 685
+ − 686 void luaC_link (lua_State *L, GCObject *o, lu_byte tt) {
+ − 687 global_State *g = G(L);
+ − 688 o->gch.next = g->rootgc;
+ − 689 g->rootgc = o;
+ − 690 o->gch.marked = luaC_white(g);
+ − 691 o->gch.tt = tt;
+ − 692 }
+ − 693
+ − 694
+ − 695 void luaC_linkupval (lua_State *L, UpVal *uv) {
+ − 696 global_State *g = G(L);
+ − 697 GCObject *o = obj2gco(uv);
+ − 698 o->gch.next = g->rootgc; /* link upvalue into `rootgc' list */
+ − 699 g->rootgc = o;
3697
+ − 700 if (isgray(o)) {
2812
+ − 701 if (g->gcstate == GCSpropagate) {
+ − 702 gray2black(o); /* closed upvalues need barrier */
+ − 703 luaC_barrier(L, uv, uv->v);
+ − 704 }
+ − 705 else { /* sweep phase: sweep it (turning it into white) */
+ − 706 makewhite(g, o);
+ − 707 lua_assert(g->gcstate != GCSfinalize && g->gcstate != GCSpause);
+ − 708 }
+ − 709 }
+ − 710 }
+ − 711