| 1 | /* |
| 2 | ** $Id: lgc.c,v 2.140 2013/03/16 21:10:18 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 | |
| 27 | /* |
| 28 | ** cost of sweeping one element (the size of a small object divided |
| 29 | ** by some adjust for the sweep speed) |
| 30 | */ |
| 31 | #define GCSWEEPCOST ((sizeof(TString) + 4) / 4) |
| 32 | |
| 33 | /* maximum number of elements to sweep in each single step */ |
| 34 | #define GCSWEEPMAX (cast_int((GCSTEPSIZE / GCSWEEPCOST) / 4)) |
| 35 | |
| 36 | /* maximum number of finalizers to call in each GC step */ |
| 37 | #define GCFINALIZENUM 4 |
| 38 | |
| 39 | |
| 40 | /* |
| 41 | ** macro to adjust 'stepmul': 'stepmul' is actually used like |
| 42 | ** 'stepmul / STEPMULADJ' (value chosen by tests) |
| 43 | */ |
| 44 | #define STEPMULADJ 200 |
| 45 | |
| 46 | |
| 47 | /* |
| 48 | ** macro to adjust 'pause': 'pause' is actually used like |
| 49 | ** 'pause / PAUSEADJ' (value chosen by tests) |
| 50 | */ |
| 51 | #define PAUSEADJ 100 |
| 52 | |
| 53 | |
| 54 | /* |
| 55 | ** 'makewhite' erases all color bits plus the old bit and then |
| 56 | ** sets only the current white bit |
| 57 | */ |
| 58 | #define maskcolors (~(bit2mask(BLACKBIT, OLDBIT) | WHITEBITS)) |
| 59 | #define makewhite(g,x) \ |
| 60 | (gch(x)->marked = cast_byte((gch(x)->marked & maskcolors) | luaC_white(g))) |
| 61 | |
| 62 | #define white2gray(x) resetbits(gch(x)->marked, WHITEBITS) |
| 63 | #define black2gray(x) resetbit(gch(x)->marked, BLACKBIT) |
| 64 | |
| 65 | |
| 66 | #define isfinalized(x) testbit(gch(x)->marked, FINALIZEDBIT) |
| 67 | |
| 68 | #define checkdeadkey(n) lua_assert(!ttisdeadkey(gkey(n)) || ttisnil(gval(n))) |
| 69 | |
| 70 | |
| 71 | #define checkconsistency(obj) \ |
| 72 | lua_longassert(!iscollectable(obj) || righttt(obj)) |
| 73 | |
| 74 | |
| 75 | #define markvalue(g,o) { checkconsistency(o); \ |
| 76 | if (valiswhite(o)) reallymarkobject(g,gcvalue(o)); } |
| 77 | |
| 78 | #define markobject(g,t) { if ((t) && iswhite(obj2gco(t))) \ |
| 79 | reallymarkobject(g, obj2gco(t)); } |
| 80 | |
| 81 | static void reallymarkobject (global_State *g, GCObject *o); |
| 82 | |
| 83 | |
| 84 | /* |
| 85 | ** {====================================================== |
| 86 | ** Generic functions |
| 87 | ** ======================================================= |
| 88 | */ |
| 89 | |
| 90 | |
| 91 | /* |
| 92 | ** one after last element in a hash array |
| 93 | */ |
| 94 | #define gnodelast(h) gnode(h, cast(size_t, sizenode(h))) |
| 95 | |
| 96 | |
| 97 | /* |
| 98 | ** link table 'h' into list pointed by 'p' |
| 99 | */ |
| 100 | #define linktable(h,p) ((h)->gclist = *(p), *(p) = obj2gco(h)) |
| 101 | |
| 102 | |
| 103 | /* |
| 104 | ** if key is not marked, mark its entry as dead (therefore removing it |
| 105 | ** from the table) |
| 106 | */ |
| 107 | static void removeentry (Node *n) { |
| 108 | lua_assert(ttisnil(gval(n))); |
| 109 | if (valiswhite(gkey(n))) |
| 110 | setdeadvalue(gkey(n)); /* unused and unmarked key; remove it */ |
| 111 | } |
| 112 | |
| 113 | |
| 114 | /* |
| 115 | ** tells whether a key or value can be cleared from a weak |
| 116 | ** table. Non-collectable objects are never removed from weak |
| 117 | ** tables. Strings behave as `values', so are never removed too. for |
| 118 | ** other objects: if really collected, cannot keep them; for objects |
| 119 | ** being finalized, keep them in keys, but not in values |
| 120 | */ |
| 121 | static int iscleared (global_State *g, const TValue *o) { |
| 122 | if (!iscollectable(o)) return 0; |
| 123 | else if (ttisstring(o)) { |
| 124 | markobject(g, rawtsvalue(o)); /* strings are `values', so are never weak */ |
| 125 | return 0; |
| 126 | } |
| 127 | else return iswhite(gcvalue(o)); |
| 128 | } |
| 129 | |
| 130 | |
| 131 | /* |
| 132 | ** barrier that moves collector forward, that is, mark the white object |
| 133 | ** being pointed by a black object. |
| 134 | */ |
| 135 | void luaC_barrier_ (lua_State *L, GCObject *o, GCObject *v) { |
| 136 | global_State *g = G(L); |
| 137 | lua_assert(isblack(o) && iswhite(v) && !isdead(g, v) && !isdead(g, o)); |
| 138 | lua_assert(g->gcstate != GCSpause); |
| 139 | lua_assert(gch(o)->tt != LUA_TTABLE); |
| 140 | if (keepinvariantout(g)) /* must keep invariant? */ |
| 141 | reallymarkobject(g, v); /* restore invariant */ |
| 142 | else { /* sweep phase */ |
| 143 | lua_assert(issweepphase(g)); |
| 144 | makewhite(g, o); /* mark main obj. as white to avoid other barriers */ |
| 145 | } |
| 146 | } |
| 147 | |
| 148 | |
| 149 | /* |
| 150 | ** barrier that moves collector backward, that is, mark the black object |
| 151 | ** pointing to a white object as gray again. (Current implementation |
| 152 | ** only works for tables; access to 'gclist' is not uniform across |
| 153 | ** different types.) |
| 154 | */ |
| 155 | void luaC_barrierback_ (lua_State *L, GCObject *o) { |
| 156 | global_State *g = G(L); |
| 157 | lua_assert(isblack(o) && !isdead(g, o) && gch(o)->tt == LUA_TTABLE); |
| 158 | black2gray(o); /* make object gray (again) */ |
| 159 | gco2t(o)->gclist = g->grayagain; |
| 160 | g->grayagain = o; |
| 161 | } |
| 162 | |
| 163 | |
| 164 | /* |
| 165 | ** barrier for prototypes. When creating first closure (cache is |
| 166 | ** NULL), use a forward barrier; this may be the only closure of the |
| 167 | ** prototype (if it is a "regular" function, with a single instance) |
| 168 | ** and the prototype may be big, so it is better to avoid traversing |
| 169 | ** it again. Otherwise, use a backward barrier, to avoid marking all |
| 170 | ** possible instances. |
| 171 | */ |
| 172 | LUAI_FUNC void luaC_barrierproto_ (lua_State *L, Proto *p, Closure *c) { |
| 173 | global_State *g = G(L); |
| 174 | lua_assert(isblack(obj2gco(p))); |
| 175 | if (p->cache == NULL) { /* first time? */ |
| 176 | luaC_objbarrier(L, p, c); |
| 177 | } |
| 178 | else { /* use a backward barrier */ |
| 179 | black2gray(obj2gco(p)); /* make prototype gray (again) */ |
| 180 | p->gclist = g->grayagain; |
| 181 | g->grayagain = obj2gco(p); |
| 182 | } |
| 183 | } |
| 184 | |
| 185 | |
| 186 | /* |
| 187 | ** check color (and invariants) for an upvalue that was closed, |
| 188 | ** i.e., moved into the 'allgc' list |
| 189 | */ |
| 190 | void luaC_checkupvalcolor (global_State *g, UpVal *uv) { |
| 191 | GCObject *o = obj2gco(uv); |
| 192 | lua_assert(!isblack(o)); /* open upvalues are never black */ |
| 193 | if (isgray(o)) { |
| 194 | if (keepinvariant(g)) { |
| 195 | resetoldbit(o); /* see MOVE OLD rule */ |
| 196 | gray2black(o); /* it is being visited now */ |
| 197 | markvalue(g, uv->v); |
| 198 | } |
| 199 | else { |
| 200 | lua_assert(issweepphase(g)); |
| 201 | makewhite(g, o); |
| 202 | } |
| 203 | } |
| 204 | } |
| 205 | |
| 206 | |
| 207 | /* |
| 208 | ** create a new collectable object (with given type and size) and link |
| 209 | ** it to '*list'. 'offset' tells how many bytes to allocate before the |
| 210 | ** object itself (used only by states). |
| 211 | */ |
| 212 | GCObject *luaC_newobj (lua_State *L, int tt, size_t sz, GCObject **list, |
| 213 | int offset) { |
| 214 | global_State *g = G(L); |
| 215 | char *raw = cast(char *, luaM_newobject(L, novariant(tt), sz)); |
| 216 | GCObject *o = obj2gco(raw + offset); |
| 217 | if (list == NULL) |
| 218 | list = &g->allgc; /* standard list for collectable objects */ |
| 219 | gch(o)->marked = luaC_white(g); |
| 220 | gch(o)->tt = tt; |
| 221 | gch(o)->next = *list; |
| 222 | *list = o; |
| 223 | return o; |
| 224 | } |
| 225 | |
| 226 | /* }====================================================== */ |
| 227 | |
| 228 | |
| 229 | |
| 230 | /* |
| 231 | ** {====================================================== |
| 232 | ** Mark functions |
| 233 | ** ======================================================= |
| 234 | */ |
| 235 | |
| 236 | |
| 237 | /* |
| 238 | ** mark an object. Userdata, strings, and closed upvalues are visited |
| 239 | ** and turned black here. Other objects are marked gray and added |
| 240 | ** to appropriate list to be visited (and turned black) later. (Open |
| 241 | ** upvalues are already linked in 'headuv' list.) |
| 242 | */ |
| 243 | static void reallymarkobject (global_State *g, GCObject *o) { |
| 244 | lu_mem size; |
| 245 | white2gray(o); |
| 246 | switch (gch(o)->tt) { |
| 247 | case LUA_TSHRSTR: |
| 248 | case LUA_TLNGSTR: { |
| 249 | size = sizestring(gco2ts(o)); |
| 250 | break; /* nothing else to mark; make it black */ |
| 251 | } |
| 252 | case LUA_TUSERDATA: { |
| 253 | Table *mt = gco2u(o)->metatable; |
| 254 | markobject(g, mt); |
| 255 | markobject(g, gco2u(o)->env); |
| 256 | size = sizeudata(gco2u(o)); |
| 257 | break; |
| 258 | } |
| 259 | case LUA_TUPVAL: { |
| 260 | UpVal *uv = gco2uv(o); |
| 261 | markvalue(g, uv->v); |
| 262 | if (uv->v != &uv->u.value) /* open? */ |
| 263 | return; /* open upvalues remain gray */ |
| 264 | size = sizeof(UpVal); |
| 265 | break; |
| 266 | } |
| 267 | case LUA_TLCL: { |
| 268 | gco2lcl(o)->gclist = g->gray; |
| 269 | g->gray = o; |
| 270 | return; |
| 271 | } |
| 272 | case LUA_TCCL: { |
| 273 | gco2ccl(o)->gclist = g->gray; |
| 274 | g->gray = o; |
| 275 | return; |
| 276 | } |
| 277 | case LUA_TTABLE: { |
| 278 | linktable(gco2t(o), &g->gray); |
| 279 | return; |
| 280 | } |
| 281 | case LUA_TTHREAD: { |
| 282 | gco2th(o)->gclist = g->gray; |
| 283 | g->gray = o; |
| 284 | return; |
| 285 | } |
| 286 | case LUA_TPROTO: { |
| 287 | gco2p(o)->gclist = g->gray; |
| 288 | g->gray = o; |
| 289 | return; |
| 290 | } |
| 291 | default: lua_assert(0); return; |
| 292 | } |
| 293 | gray2black(o); |
| 294 | g->GCmemtrav += size; |
| 295 | } |
| 296 | |
| 297 | |
| 298 | /* |
| 299 | ** mark metamethods for basic types |
| 300 | */ |
| 301 | static void markmt (global_State *g) { |
| 302 | int i; |
| 303 | for (i=0; i < LUA_NUMTAGS; i++) |
| 304 | markobject(g, g->mt[i]); |
| 305 | } |
| 306 | |
| 307 | |
| 308 | /* |
| 309 | ** mark all objects in list of being-finalized |
| 310 | */ |
| 311 | static void markbeingfnz (global_State *g) { |
| 312 | GCObject *o; |
| 313 | for (o = g->tobefnz; o != NULL; o = gch(o)->next) { |
| 314 | makewhite(g, o); |
| 315 | reallymarkobject(g, o); |
| 316 | } |
| 317 | } |
| 318 | |
| 319 | |
| 320 | /* |
| 321 | ** mark all values stored in marked open upvalues. (See comment in |
| 322 | ** 'lstate.h'.) |
| 323 | */ |
| 324 | static void remarkupvals (global_State *g) { |
| 325 | UpVal *uv; |
| 326 | for (uv = g->uvhead.u.l.next; uv != &g->uvhead; uv = uv->u.l.next) { |
| 327 | if (isgray(obj2gco(uv))) |
| 328 | markvalue(g, uv->v); |
| 329 | } |
| 330 | } |
| 331 | |
| 332 | |
| 333 | /* |
| 334 | ** mark root set and reset all gray lists, to start a new |
| 335 | ** incremental (or full) collection |
| 336 | */ |
| 337 | static void restartcollection (global_State *g) { |
| 338 | g->gray = g->grayagain = NULL; |
| 339 | g->weak = g->allweak = g->ephemeron = NULL; |
| 340 | markobject(g, g->mainthread); |
| 341 | markvalue(g, &g->l_registry); |
| 342 | markmt(g); |
| 343 | markbeingfnz(g); /* mark any finalizing object left from previous cycle */ |
| 344 | } |
| 345 | |
| 346 | /* }====================================================== */ |
| 347 | |
| 348 | |
| 349 | /* |
| 350 | ** {====================================================== |
| 351 | ** Traverse functions |
| 352 | ** ======================================================= |
| 353 | */ |
| 354 | |
| 355 | static void traverseweakvalue (global_State *g, Table *h) { |
| 356 | Node *n, *limit = gnodelast(h); |
| 357 | /* if there is array part, assume it may have white values (do not |
| 358 | traverse it just to check) */ |
| 359 | int hasclears = (h->sizearray > 0); |
| 360 | for (n = gnode(h, 0); n < limit; n++) { |
| 361 | checkdeadkey(n); |
| 362 | if (ttisnil(gval(n))) /* entry is empty? */ |
| 363 | removeentry(n); /* remove it */ |
| 364 | else { |
| 365 | lua_assert(!ttisnil(gkey(n))); |
| 366 | markvalue(g, gkey(n)); /* mark key */ |
| 367 | if (!hasclears && iscleared(g, gval(n))) /* is there a white value? */ |
| 368 | hasclears = 1; /* table will have to be cleared */ |
| 369 | } |
| 370 | } |
| 371 | if (hasclears) |
| 372 | linktable(h, &g->weak); /* has to be cleared later */ |
| 373 | else /* no white values */ |
| 374 | linktable(h, &g->grayagain); /* no need to clean */ |
| 375 | } |
| 376 | |
| 377 | |
| 378 | static int traverseephemeron (global_State *g, Table *h) { |
| 379 | int marked = 0; /* true if an object is marked in this traversal */ |
| 380 | int hasclears = 0; /* true if table has white keys */ |
| 381 | int prop = 0; /* true if table has entry "white-key -> white-value" */ |
| 382 | Node *n, *limit = gnodelast(h); |
| 383 | int i; |
| 384 | /* traverse array part (numeric keys are 'strong') */ |
| 385 | for (i = 0; i < h->sizearray; i++) { |
| 386 | if (valiswhite(&h->array[i])) { |
| 387 | marked = 1; |
| 388 | reallymarkobject(g, gcvalue(&h->array[i])); |
| 389 | } |
| 390 | } |
| 391 | /* traverse hash part */ |
| 392 | for (n = gnode(h, 0); n < limit; n++) { |
| 393 | checkdeadkey(n); |
| 394 | if (ttisnil(gval(n))) /* entry is empty? */ |
| 395 | removeentry(n); /* remove it */ |
| 396 | else if (iscleared(g, gkey(n))) { /* key is not marked (yet)? */ |
| 397 | hasclears = 1; /* table must be cleared */ |
| 398 | if (valiswhite(gval(n))) /* value not marked yet? */ |
| 399 | prop = 1; /* must propagate again */ |
| 400 | } |
| 401 | else if (valiswhite(gval(n))) { /* value not marked yet? */ |
| 402 | marked = 1; |
| 403 | reallymarkobject(g, gcvalue(gval(n))); /* mark it now */ |
| 404 | } |
| 405 | } |
| 406 | if (prop) |
| 407 | linktable(h, &g->ephemeron); /* have to propagate again */ |
| 408 | else if (hasclears) /* does table have white keys? */ |
| 409 | linktable(h, &g->allweak); /* may have to clean white keys */ |
| 410 | else /* no white keys */ |
| 411 | linktable(h, &g->grayagain); /* no need to clean */ |
| 412 | return marked; |
| 413 | } |
| 414 | |
| 415 | |
| 416 | static void traversestrongtable (global_State *g, Table *h) { |
| 417 | Node *n, *limit = gnodelast(h); |
| 418 | int i; |
| 419 | for (i = 0; i < h->sizearray; i++) /* traverse array part */ |
| 420 | markvalue(g, &h->array[i]); |
| 421 | for (n = gnode(h, 0); n < limit; n++) { /* traverse hash part */ |
| 422 | checkdeadkey(n); |
| 423 | if (ttisnil(gval(n))) /* entry is empty? */ |
| 424 | removeentry(n); /* remove it */ |
| 425 | else { |
| 426 | lua_assert(!ttisnil(gkey(n))); |
| 427 | markvalue(g, gkey(n)); /* mark key */ |
| 428 | markvalue(g, gval(n)); /* mark value */ |
| 429 | } |
| 430 | } |
| 431 | } |
| 432 | |
| 433 | |
| 434 | static lu_mem traversetable (global_State *g, Table *h) { |
| 435 | const char *weakkey, *weakvalue; |
| 436 | const TValue *mode = gfasttm(g, h->metatable, TM_MODE); |
| 437 | markobject(g, h->metatable); |
| 438 | if (mode && ttisstring(mode) && /* is there a weak mode? */ |
| 439 | ((weakkey = strchr(svalue(mode), 'k')), |
| 440 | (weakvalue = strchr(svalue(mode), 'v')), |
| 441 | (weakkey || weakvalue))) { /* is really weak? */ |
| 442 | black2gray(obj2gco(h)); /* keep table gray */ |
| 443 | if (!weakkey) /* strong keys? */ |
| 444 | traverseweakvalue(g, h); |
| 445 | else if (!weakvalue) /* strong values? */ |
| 446 | traverseephemeron(g, h); |
| 447 | else /* all weak */ |
| 448 | linktable(h, &g->allweak); /* nothing to traverse now */ |
| 449 | } |
| 450 | else /* not weak */ |
| 451 | traversestrongtable(g, h); |
| 452 | return sizeof(Table) + sizeof(TValue) * h->sizearray + |
| 453 | sizeof(Node) * cast(size_t, sizenode(h)); |
| 454 | } |
| 455 | |
| 456 | |
| 457 | static int traverseproto (global_State *g, Proto *f) { |
| 458 | int i; |
| 459 | if (f->cache && iswhite(obj2gco(f->cache))) |
| 460 | f->cache = NULL; /* allow cache to be collected */ |
| 461 | markobject(g, f->source); |
| 462 | for (i = 0; i < f->sizek; i++) /* mark literals */ |
| 463 | markvalue(g, &f->k[i]); |
| 464 | for (i = 0; i < f->sizeupvalues; i++) /* mark upvalue names */ |
| 465 | markobject(g, f->upvalues[i].name); |
| 466 | for (i = 0; i < f->sizep; i++) /* mark nested protos */ |
| 467 | markobject(g, f->p[i]); |
| 468 | for (i = 0; i < f->sizelocvars; i++) /* mark local-variable names */ |
| 469 | markobject(g, f->locvars[i].varname); |
| 470 | return sizeof(Proto) + sizeof(Instruction) * f->sizecode + |
| 471 | sizeof(Proto *) * f->sizep + |
| 472 | sizeof(TValue) * f->sizek + |
| 473 | sizeof(int) * f->sizelineinfo + |
| 474 | sizeof(LocVar) * f->sizelocvars + |
| 475 | sizeof(Upvaldesc) * f->sizeupvalues; |
| 476 | } |
| 477 | |
| 478 | |
| 479 | static lu_mem traverseCclosure (global_State *g, CClosure *cl) { |
| 480 | int i; |
| 481 | for (i = 0; i < cl->nupvalues; i++) /* mark its upvalues */ |
| 482 | markvalue(g, &cl->upvalue[i]); |
| 483 | return sizeCclosure(cl->nupvalues); |
| 484 | } |
| 485 | |
| 486 | static lu_mem traverseLclosure (global_State *g, LClosure *cl) { |
| 487 | int i; |
| 488 | markobject(g, cl->p); /* mark its prototype */ |
| 489 | for (i = 0; i < cl->nupvalues; i++) /* mark its upvalues */ |
| 490 | markobject(g, cl->upvals[i]); |
| 491 | return sizeLclosure(cl->nupvalues); |
| 492 | } |
| 493 | |
| 494 | |
| 495 | static lu_mem traversestack (global_State *g, lua_State *th) { |
| 496 | StkId o = th->stack; |
| 497 | if (o == NULL) |
| 498 | return 1; /* stack not completely built yet */ |
| 499 | for (; o < th->top; o++) |
| 500 | markvalue(g, o); |
| 501 | if (g->gcstate == GCSatomic) { /* final traversal? */ |
| 502 | StkId lim = th->stack + th->stacksize; /* real end of stack */ |
| 503 | for (; o < lim; o++) /* clear not-marked stack slice */ |
| 504 | setnilvalue(o); |
| 505 | } |
| 506 | return sizeof(lua_State) + sizeof(TValue) * th->stacksize; |
| 507 | } |
| 508 | |
| 509 | |
| 510 | /* |
| 511 | ** traverse one gray object, turning it to black (except for threads, |
| 512 | ** which are always gray). |
| 513 | */ |
| 514 | static void propagatemark (global_State *g) { |
| 515 | lu_mem size; |
| 516 | GCObject *o = g->gray; |
| 517 | lua_assert(isgray(o)); |
| 518 | gray2black(o); |
| 519 | switch (gch(o)->tt) { |
| 520 | case LUA_TTABLE: { |
| 521 | Table *h = gco2t(o); |
| 522 | g->gray = h->gclist; /* remove from 'gray' list */ |
| 523 | size = traversetable(g, h); |
| 524 | break; |
| 525 | } |
| 526 | case LUA_TLCL: { |
| 527 | LClosure *cl = gco2lcl(o); |
| 528 | g->gray = cl->gclist; /* remove from 'gray' list */ |
| 529 | size = traverseLclosure(g, cl); |
| 530 | break; |
| 531 | } |
| 532 | case LUA_TCCL: { |
| 533 | CClosure *cl = gco2ccl(o); |
| 534 | g->gray = cl->gclist; /* remove from 'gray' list */ |
| 535 | size = traverseCclosure(g, cl); |
| 536 | break; |
| 537 | } |
| 538 | case LUA_TTHREAD: { |
| 539 | lua_State *th = gco2th(o); |
| 540 | g->gray = th->gclist; /* remove from 'gray' list */ |
| 541 | th->gclist = g->grayagain; |
| 542 | g->grayagain = o; /* insert into 'grayagain' list */ |
| 543 | black2gray(o); |
| 544 | size = traversestack(g, th); |
| 545 | break; |
| 546 | } |
| 547 | case LUA_TPROTO: { |
| 548 | Proto *p = gco2p(o); |
| 549 | g->gray = p->gclist; /* remove from 'gray' list */ |
| 550 | size = traverseproto(g, p); |
| 551 | break; |
| 552 | } |
| 553 | default: lua_assert(0); return; |
| 554 | } |
| 555 | g->GCmemtrav += size; |
| 556 | } |
| 557 | |
| 558 | |
| 559 | static void propagateall (global_State *g) { |
| 560 | while (g->gray) propagatemark(g); |
| 561 | } |
| 562 | |
| 563 | |
| 564 | static void propagatelist (global_State *g, GCObject *l) { |
| 565 | lua_assert(g->gray == NULL); /* no grays left */ |
| 566 | g->gray = l; |
| 567 | propagateall(g); /* traverse all elements from 'l' */ |
| 568 | } |
| 569 | |
| 570 | /* |
| 571 | ** retraverse all gray lists. Because tables may be reinserted in other |
| 572 | ** lists when traversed, traverse the original lists to avoid traversing |
| 573 | ** twice the same table (which is not wrong, but inefficient) |
| 574 | */ |
| 575 | static void retraversegrays (global_State *g) { |
| 576 | GCObject *weak = g->weak; /* save original lists */ |
| 577 | GCObject *grayagain = g->grayagain; |
| 578 | GCObject *ephemeron = g->ephemeron; |
| 579 | g->weak = g->grayagain = g->ephemeron = NULL; |
| 580 | propagateall(g); /* traverse main gray list */ |
| 581 | propagatelist(g, grayagain); |
| 582 | propagatelist(g, weak); |
| 583 | propagatelist(g, ephemeron); |
| 584 | } |
| 585 | |
| 586 | |
| 587 | static void convergeephemerons (global_State *g) { |
| 588 | int changed; |
| 589 | do { |
| 590 | GCObject *w; |
| 591 | GCObject *next = g->ephemeron; /* get ephemeron list */ |
| 592 | g->ephemeron = NULL; /* tables will return to this list when traversed */ |
| 593 | changed = 0; |
| 594 | while ((w = next) != NULL) { |
| 595 | next = gco2t(w)->gclist; |
| 596 | if (traverseephemeron(g, gco2t(w))) { /* traverse marked some value? */ |
| 597 | propagateall(g); /* propagate changes */ |
| 598 | changed = 1; /* will have to revisit all ephemeron tables */ |
| 599 | } |
| 600 | } |
| 601 | } while (changed); |
| 602 | } |
| 603 | |
| 604 | /* }====================================================== */ |
| 605 | |
| 606 | |
| 607 | /* |
| 608 | ** {====================================================== |
| 609 | ** Sweep Functions |
| 610 | ** ======================================================= |
| 611 | */ |
| 612 | |
| 613 | |
| 614 | /* |
| 615 | ** clear entries with unmarked keys from all weaktables in list 'l' up |
| 616 | ** to element 'f' |
| 617 | */ |
| 618 | static void clearkeys (global_State *g, GCObject *l, GCObject *f) { |
| 619 | for (; l != f; l = gco2t(l)->gclist) { |
| 620 | Table *h = gco2t(l); |
| 621 | Node *n, *limit = gnodelast(h); |
| 622 | for (n = gnode(h, 0); n < limit; n++) { |
| 623 | if (!ttisnil(gval(n)) && (iscleared(g, gkey(n)))) { |
| 624 | setnilvalue(gval(n)); /* remove value ... */ |
| 625 | removeentry(n); /* and remove entry from table */ |
| 626 | } |
| 627 | } |
| 628 | } |
| 629 | } |
| 630 | |
| 631 | |
| 632 | /* |
| 633 | ** clear entries with unmarked values from all weaktables in list 'l' up |
| 634 | ** to element 'f' |
| 635 | */ |
| 636 | static void clearvalues (global_State *g, GCObject *l, GCObject *f) { |
| 637 | for (; l != f; l = gco2t(l)->gclist) { |
| 638 | Table *h = gco2t(l); |
| 639 | Node *n, *limit = gnodelast(h); |
| 640 | int i; |
| 641 | for (i = 0; i < h->sizearray; i++) { |
| 642 | TValue *o = &h->array[i]; |
| 643 | if (iscleared(g, o)) /* value was collected? */ |
| 644 | setnilvalue(o); /* remove value */ |
| 645 | } |
| 646 | for (n = gnode(h, 0); n < limit; n++) { |
| 647 | if (!ttisnil(gval(n)) && iscleared(g, gval(n))) { |
| 648 | setnilvalue(gval(n)); /* remove value ... */ |
| 649 | removeentry(n); /* and remove entry from table */ |
| 650 | } |
| 651 | } |
| 652 | } |
| 653 | } |
| 654 | |
| 655 | |
| 656 | static void freeobj (lua_State *L, GCObject *o) { |
| 657 | switch (gch(o)->tt) { |
| 658 | case LUA_TPROTO: luaF_freeproto(L, gco2p(o)); break; |
| 659 | case LUA_TLCL: { |
| 660 | luaM_freemem(L, o, sizeLclosure(gco2lcl(o)->nupvalues)); |
| 661 | break; |
| 662 | } |
| 663 | case LUA_TCCL: { |
| 664 | luaM_freemem(L, o, sizeCclosure(gco2ccl(o)->nupvalues)); |
| 665 | break; |
| 666 | } |
| 667 | case LUA_TUPVAL: luaF_freeupval(L, gco2uv(o)); break; |
| 668 | case LUA_TTABLE: luaH_free(L, gco2t(o)); break; |
| 669 | case LUA_TTHREAD: luaE_freethread(L, gco2th(o)); break; |
| 670 | case LUA_TUSERDATA: luaM_freemem(L, o, sizeudata(gco2u(o))); break; |
| 671 | case LUA_TSHRSTR: |
| 672 | G(L)->strt.nuse--; |
| 673 | /* go through */ |
| 674 | case LUA_TLNGSTR: { |
| 675 | luaM_freemem(L, o, sizestring(gco2ts(o))); |
| 676 | break; |
| 677 | } |
| 678 | default: lua_assert(0); |
| 679 | } |
| 680 | } |
| 681 | |
| 682 | |
| 683 | #define sweepwholelist(L,p) sweeplist(L,p,MAX_LUMEM) |
| 684 | static GCObject **sweeplist (lua_State *L, GCObject **p, lu_mem count); |
| 685 | |
| 686 | |
| 687 | /* |
| 688 | ** sweep the (open) upvalues of a thread and resize its stack and |
| 689 | ** list of call-info structures. |
| 690 | */ |
| 691 | static void sweepthread (lua_State *L, lua_State *L1) { |
| 692 | if (L1->stack == NULL) return; /* stack not completely built yet */ |
| 693 | sweepwholelist(L, &L1->openupval); /* sweep open upvalues */ |
| 694 | luaE_freeCI(L1); /* free extra CallInfo slots */ |
| 695 | /* should not change the stack during an emergency gc cycle */ |
| 696 | if (G(L)->gckind != KGC_EMERGENCY) |
| 697 | luaD_shrinkstack(L1); |
| 698 | } |
| 699 | |
| 700 | |
| 701 | /* |
| 702 | ** sweep at most 'count' elements from a list of GCObjects erasing dead |
| 703 | ** objects, where a dead (not alive) object is one marked with the "old" |
| 704 | ** (non current) white and not fixed. |
| 705 | ** In non-generational mode, change all non-dead objects back to white, |
| 706 | ** preparing for next collection cycle. |
| 707 | ** In generational mode, keep black objects black, and also mark them as |
| 708 | ** old; stop when hitting an old object, as all objects after that |
| 709 | ** one will be old too. |
| 710 | ** When object is a thread, sweep its list of open upvalues too. |
| 711 | */ |
| 712 | static GCObject **sweeplist (lua_State *L, GCObject **p, lu_mem count) { |
| 713 | global_State *g = G(L); |
| 714 | int ow = otherwhite(g); |
| 715 | int toclear, toset; /* bits to clear and to set in all live objects */ |
| 716 | int tostop; /* stop sweep when this is true */ |
| 717 | if (isgenerational(g)) { /* generational mode? */ |
| 718 | toclear = ~0; /* clear nothing */ |
| 719 | toset = bitmask(OLDBIT); /* set the old bit of all surviving objects */ |
| 720 | tostop = bitmask(OLDBIT); /* do not sweep old generation */ |
| 721 | } |
| 722 | else { /* normal mode */ |
| 723 | toclear = maskcolors; /* clear all color bits + old bit */ |
| 724 | toset = luaC_white(g); /* make object white */ |
| 725 | tostop = 0; /* do not stop */ |
| 726 | } |
| 727 | while (*p != NULL && count-- > 0) { |
| 728 | GCObject *curr = *p; |
| 729 | int marked = gch(curr)->marked; |
| 730 | if (isdeadm(ow, marked)) { /* is 'curr' dead? */ |
| 731 | *p = gch(curr)->next; /* remove 'curr' from list */ |
| 732 | freeobj(L, curr); /* erase 'curr' */ |
| 733 | } |
| 734 | else { |
| 735 | if (testbits(marked, tostop)) |
| 736 | return NULL; /* stop sweeping this list */ |
| 737 | if (gch(curr)->tt == LUA_TTHREAD) |
| 738 | sweepthread(L, gco2th(curr)); /* sweep thread's upvalues */ |
| 739 | /* update marks */ |
| 740 | gch(curr)->marked = cast_byte((marked & toclear) | toset); |
| 741 | p = &gch(curr)->next; /* go to next element */ |
| 742 | } |
| 743 | } |
| 744 | return (*p == NULL) ? NULL : p; |
| 745 | } |
| 746 | |
| 747 | |
| 748 | /* |
| 749 | ** sweep a list until a live object (or end of list) |
| 750 | */ |
| 751 | static GCObject **sweeptolive (lua_State *L, GCObject **p, int *n) { |
| 752 | GCObject ** old = p; |
| 753 | int i = 0; |
| 754 | do { |
| 755 | i++; |
| 756 | p = sweeplist(L, p, 1); |
| 757 | } while (p == old); |
| 758 | if (n) *n += i; |
| 759 | return p; |
| 760 | } |
| 761 | |
| 762 | /* }====================================================== */ |
| 763 | |
| 764 | |
| 765 | /* |
| 766 | ** {====================================================== |
| 767 | ** Finalization |
| 768 | ** ======================================================= |
| 769 | */ |
| 770 | |
| 771 | static void checkSizes (lua_State *L) { |
| 772 | global_State *g = G(L); |
| 773 | if (g->gckind != KGC_EMERGENCY) { /* do not change sizes in emergency */ |
| 774 | int hs = g->strt.size / 2; /* half the size of the string table */ |
| 775 | if (g->strt.nuse < cast(lu_int32, hs)) /* using less than that half? */ |
| 776 | luaS_resize(L, hs); /* halve its size */ |
| 777 | luaZ_freebuffer(L, &g->buff); /* free concatenation buffer */ |
| 778 | } |
| 779 | } |
| 780 | |
| 781 | |
| 782 | static GCObject *udata2finalize (global_State *g) { |
| 783 | GCObject *o = g->tobefnz; /* get first element */ |
| 784 | lua_assert(isfinalized(o)); |
| 785 | g->tobefnz = gch(o)->next; /* remove it from 'tobefnz' list */ |
| 786 | gch(o)->next = g->allgc; /* return it to 'allgc' list */ |
| 787 | g->allgc = o; |
| 788 | resetbit(gch(o)->marked, SEPARATED); /* mark that it is not in 'tobefnz' */ |
| 789 | lua_assert(!isold(o)); /* see MOVE OLD rule */ |
| 790 | if (!keepinvariantout(g)) /* not keeping invariant? */ |
| 791 | makewhite(g, o); /* "sweep" object */ |
| 792 | return o; |
| 793 | } |
| 794 | |
| 795 | |
| 796 | static void dothecall (lua_State *L, void *ud) { |
| 797 | UNUSED(ud); |
| 798 | luaD_call(L, L->top - 2, 0, 0); |
| 799 | } |
| 800 | |
| 801 | |
| 802 | static void GCTM (lua_State *L, int propagateerrors) { |
| 803 | global_State *g = G(L); |
| 804 | const TValue *tm; |
| 805 | TValue v; |
| 806 | setgcovalue(L, &v, udata2finalize(g)); |
| 807 | tm = luaT_gettmbyobj(L, &v, TM_GC); |
| 808 | if (tm != NULL && ttisfunction(tm)) { /* is there a finalizer? */ |
| 809 | int status; |
| 810 | lu_byte oldah = L->allowhook; |
| 811 | int running = g->gcrunning; |
| 812 | L->allowhook = 0; /* stop debug hooks during GC metamethod */ |
| 813 | g->gcrunning = 0; /* avoid GC steps */ |
| 814 | setobj2s(L, L->top, tm); /* push finalizer... */ |
| 815 | setobj2s(L, L->top + 1, &v); /* ... and its argument */ |
| 816 | L->top += 2; /* and (next line) call the finalizer */ |
| 817 | status = luaD_pcall(L, dothecall, NULL, savestack(L, L->top - 2), 0); |
| 818 | L->allowhook = oldah; /* restore hooks */ |
| 819 | g->gcrunning = running; /* restore state */ |
| 820 | if (status != LUA_OK && propagateerrors) { /* error while running __gc? */ |
| 821 | if (status == LUA_ERRRUN) { /* is there an error object? */ |
| 822 | const char *msg = (ttisstring(L->top - 1)) |
| 823 | ? svalue(L->top - 1) |
| 824 | : "no message"; |
| 825 | luaO_pushfstring(L, "error in __gc metamethod (%s)", msg); |
| 826 | status = LUA_ERRGCMM; /* error in __gc metamethod */ |
| 827 | } |
| 828 | luaD_throw(L, status); /* re-throw error */ |
| 829 | } |
| 830 | } |
| 831 | } |
| 832 | |
| 833 | |
| 834 | /* |
| 835 | ** move all unreachable objects (or 'all' objects) that need |
| 836 | ** finalization from list 'finobj' to list 'tobefnz' (to be finalized) |
| 837 | */ |
| 838 | static void separatetobefnz (lua_State *L, int all) { |
| 839 | global_State *g = G(L); |
| 840 | GCObject **p = &g->finobj; |
| 841 | GCObject *curr; |
| 842 | GCObject **lastnext = &g->tobefnz; |
| 843 | /* find last 'next' field in 'tobefnz' list (to add elements in its end) */ |
| 844 | while (*lastnext != NULL) |
| 845 | lastnext = &gch(*lastnext)->next; |
| 846 | while ((curr = *p) != NULL) { /* traverse all finalizable objects */ |
| 847 | lua_assert(!isfinalized(curr)); |
| 848 | lua_assert(testbit(gch(curr)->marked, SEPARATED)); |
| 849 | if (!(iswhite(curr) || all)) /* not being collected? */ |
| 850 | p = &gch(curr)->next; /* don't bother with it */ |
| 851 | else { |
| 852 | l_setbit(gch(curr)->marked, FINALIZEDBIT); /* won't be finalized again */ |
| 853 | *p = gch(curr)->next; /* remove 'curr' from 'finobj' list */ |
| 854 | gch(curr)->next = *lastnext; /* link at the end of 'tobefnz' list */ |
| 855 | *lastnext = curr; |
| 856 | lastnext = &gch(curr)->next; |
| 857 | } |
| 858 | } |
| 859 | } |
| 860 | |
| 861 | |
| 862 | /* |
| 863 | ** if object 'o' has a finalizer, remove it from 'allgc' list (must |
| 864 | ** search the list to find it) and link it in 'finobj' list. |
| 865 | */ |
| 866 | void luaC_checkfinalizer (lua_State *L, GCObject *o, Table *mt) { |
| 867 | global_State *g = G(L); |
| 868 | if (testbit(gch(o)->marked, SEPARATED) || /* obj. is already separated... */ |
| 869 | isfinalized(o) || /* ... or is finalized... */ |
| 870 | gfasttm(g, mt, TM_GC) == NULL) /* or has no finalizer? */ |
| 871 | return; /* nothing to be done */ |
| 872 | else { /* move 'o' to 'finobj' list */ |
| 873 | GCObject **p; |
| 874 | GCheader *ho = gch(o); |
| 875 | if (g->sweepgc == &ho->next) { /* avoid removing current sweep object */ |
| 876 | lua_assert(issweepphase(g)); |
| 877 | g->sweepgc = sweeptolive(L, g->sweepgc, NULL); |
| 878 | } |
| 879 | /* search for pointer pointing to 'o' */ |
| 880 | for (p = &g->allgc; *p != o; p = &gch(*p)->next) { /* empty */ } |
| 881 | *p = ho->next; /* remove 'o' from root list */ |
| 882 | ho->next = g->finobj; /* link it in list 'finobj' */ |
| 883 | g->finobj = o; |
| 884 | l_setbit(ho->marked, SEPARATED); /* mark it as such */ |
| 885 | if (!keepinvariantout(g)) /* not keeping invariant? */ |
| 886 | makewhite(g, o); /* "sweep" object */ |
| 887 | else |
| 888 | resetoldbit(o); /* see MOVE OLD rule */ |
| 889 | } |
| 890 | } |
| 891 | |
| 892 | /* }====================================================== */ |
| 893 | |
| 894 | |
| 895 | /* |
| 896 | ** {====================================================== |
| 897 | ** GC control |
| 898 | ** ======================================================= |
| 899 | */ |
| 900 | |
| 901 | |
| 902 | /* |
| 903 | ** set a reasonable "time" to wait before starting a new GC cycle; |
| 904 | ** cycle will start when memory use hits threshold |
| 905 | */ |
| 906 | static void setpause (global_State *g, l_mem estimate) { |
| 907 | l_mem debt, threshold; |
| 908 | estimate = estimate / PAUSEADJ; /* adjust 'estimate' */ |
| 909 | threshold = (g->gcpause < MAX_LMEM / estimate) /* overflow? */ |
| 910 | ? estimate * g->gcpause /* no overflow */ |
| 911 | : MAX_LMEM; /* overflow; truncate to maximum */ |
| 912 | debt = -cast(l_mem, threshold - gettotalbytes(g)); |
| 913 | luaE_setdebt(g, debt); |
| 914 | } |
| 915 | |
| 916 | |
| 917 | #define sweepphases \ |
| 918 | (bitmask(GCSsweepstring) | bitmask(GCSsweepudata) | bitmask(GCSsweep)) |
| 919 | |
| 920 | |
| 921 | /* |
| 922 | ** enter first sweep phase (strings) and prepare pointers for other |
| 923 | ** sweep phases. The calls to 'sweeptolive' make pointers point to an |
| 924 | ** object inside the list (instead of to the header), so that the real |
| 925 | ** sweep do not need to skip objects created between "now" and the start |
| 926 | ** of the real sweep. |
| 927 | ** Returns how many objects it swept. |
| 928 | */ |
| 929 | static int entersweep (lua_State *L) { |
| 930 | global_State *g = G(L); |
| 931 | int n = 0; |
| 932 | g->gcstate = GCSsweepstring; |
| 933 | lua_assert(g->sweepgc == NULL && g->sweepfin == NULL); |
| 934 | /* prepare to sweep strings, finalizable objects, and regular objects */ |
| 935 | g->sweepstrgc = 0; |
| 936 | g->sweepfin = sweeptolive(L, &g->finobj, &n); |
| 937 | g->sweepgc = sweeptolive(L, &g->allgc, &n); |
| 938 | return n; |
| 939 | } |
| 940 | |
| 941 | |
| 942 | /* |
| 943 | ** change GC mode |
| 944 | */ |
| 945 | void luaC_changemode (lua_State *L, int mode) { |
| 946 | global_State *g = G(L); |
| 947 | if (mode == g->gckind) return; /* nothing to change */ |
| 948 | if (mode == KGC_GEN) { /* change to generational mode */ |
| 949 | /* make sure gray lists are consistent */ |
| 950 | luaC_runtilstate(L, bitmask(GCSpropagate)); |
| 951 | g->GCestimate = gettotalbytes(g); |
| 952 | g->gckind = KGC_GEN; |
| 953 | } |
| 954 | else { /* change to incremental mode */ |
| 955 | /* sweep all objects to turn them back to white |
| 956 | (as white has not changed, nothing extra will be collected) */ |
| 957 | g->gckind = KGC_NORMAL; |
| 958 | entersweep(L); |
| 959 | luaC_runtilstate(L, ~sweepphases); |
| 960 | } |
| 961 | } |
| 962 | |
| 963 | |
| 964 | /* |
| 965 | ** call all pending finalizers |
| 966 | */ |
| 967 | static void callallpendingfinalizers (lua_State *L, int propagateerrors) { |
| 968 | global_State *g = G(L); |
| 969 | while (g->tobefnz) { |
| 970 | resetoldbit(g->tobefnz); |
| 971 | GCTM(L, propagateerrors); |
| 972 | } |
| 973 | } |
| 974 | |
| 975 | |
| 976 | void luaC_freeallobjects (lua_State *L) { |
| 977 | global_State *g = G(L); |
| 978 | int i; |
| 979 | separatetobefnz(L, 1); /* separate all objects with finalizers */ |
| 980 | lua_assert(g->finobj == NULL); |
| 981 | callallpendingfinalizers(L, 0); |
| 982 | g->currentwhite = WHITEBITS; /* this "white" makes all objects look dead */ |
| 983 | g->gckind = KGC_NORMAL; |
| 984 | sweepwholelist(L, &g->finobj); /* finalizers can create objs. in 'finobj' */ |
| 985 | sweepwholelist(L, &g->allgc); |
| 986 | for (i = 0; i < g->strt.size; i++) /* free all string lists */ |
| 987 | sweepwholelist(L, &g->strt.hash[i]); |
| 988 | lua_assert(g->strt.nuse == 0); |
| 989 | } |
| 990 | |
| 991 | |
| 992 | static l_mem atomic (lua_State *L) { |
| 993 | global_State *g = G(L); |
| 994 | l_mem work = -cast(l_mem, g->GCmemtrav); /* start counting work */ |
| 995 | GCObject *origweak, *origall; |
| 996 | lua_assert(!iswhite(obj2gco(g->mainthread))); |
| 997 | markobject(g, L); /* mark running thread */ |
| 998 | /* registry and global metatables may be changed by API */ |
| 999 | markvalue(g, &g->l_registry); |
| 1000 | markmt(g); /* mark basic metatables */ |
| 1001 | /* remark occasional upvalues of (maybe) dead threads */ |
| 1002 | remarkupvals(g); |
| 1003 | propagateall(g); /* propagate changes */ |
| 1004 | work += g->GCmemtrav; /* stop counting (do not (re)count grays) */ |
| 1005 | /* traverse objects caught by write barrier and by 'remarkupvals' */ |
| 1006 | retraversegrays(g); |
| 1007 | work -= g->GCmemtrav; /* restart counting */ |
| 1008 | convergeephemerons(g); |
| 1009 | /* at this point, all strongly accessible objects are marked. */ |
| 1010 | /* clear values from weak tables, before checking finalizers */ |
| 1011 | clearvalues(g, g->weak, NULL); |
| 1012 | clearvalues(g, g->allweak, NULL); |
| 1013 | origweak = g->weak; origall = g->allweak; |
| 1014 | work += g->GCmemtrav; /* stop counting (objects being finalized) */ |
| 1015 | separatetobefnz(L, 0); /* separate objects to be finalized */ |
| 1016 | markbeingfnz(g); /* mark objects that will be finalized */ |
| 1017 | propagateall(g); /* remark, to propagate `preserveness' */ |
| 1018 | work -= g->GCmemtrav; /* restart counting */ |
| 1019 | convergeephemerons(g); |
| 1020 | /* at this point, all resurrected objects are marked. */ |
| 1021 | /* remove dead objects from weak tables */ |
| 1022 | clearkeys(g, g->ephemeron, NULL); /* clear keys from all ephemeron tables */ |
| 1023 | clearkeys(g, g->allweak, NULL); /* clear keys from all allweak tables */ |
| 1024 | /* clear values from resurrected weak tables */ |
| 1025 | clearvalues(g, g->weak, origweak); |
| 1026 | clearvalues(g, g->allweak, origall); |
| 1027 | g->currentwhite = cast_byte(otherwhite(g)); /* flip current white */ |
| 1028 | work += g->GCmemtrav; /* complete counting */ |
| 1029 | return work; /* estimate of memory marked by 'atomic' */ |
| 1030 | } |
| 1031 | |
| 1032 | |
| 1033 | static lu_mem singlestep (lua_State *L) { |
| 1034 | global_State *g = G(L); |
| 1035 | switch (g->gcstate) { |
| 1036 | case GCSpause: { |
| 1037 | /* start to count memory traversed */ |
| 1038 | g->GCmemtrav = g->strt.size * sizeof(GCObject*); |
| 1039 | lua_assert(!isgenerational(g)); |
| 1040 | restartcollection(g); |
| 1041 | g->gcstate = GCSpropagate; |
| 1042 | return g->GCmemtrav; |
| 1043 | } |
| 1044 | case GCSpropagate: { |
| 1045 | if (g->gray) { |
| 1046 | lu_mem oldtrav = g->GCmemtrav; |
| 1047 | propagatemark(g); |
| 1048 | return g->GCmemtrav - oldtrav; /* memory traversed in this step */ |
| 1049 | } |
| 1050 | else { /* no more `gray' objects */ |
| 1051 | lu_mem work; |
| 1052 | int sw; |
| 1053 | g->gcstate = GCSatomic; /* finish mark phase */ |
| 1054 | g->GCestimate = g->GCmemtrav; /* save what was counted */; |
| 1055 | work = atomic(L); /* add what was traversed by 'atomic' */ |
| 1056 | g->GCestimate += work; /* estimate of total memory traversed */ |
| 1057 | sw = entersweep(L); |
| 1058 | return work + sw * GCSWEEPCOST; |
| 1059 | } |
| 1060 | } |
| 1061 | case GCSsweepstring: { |
| 1062 | int i; |
| 1063 | for (i = 0; i < GCSWEEPMAX && g->sweepstrgc + i < g->strt.size; i++) |
| 1064 | sweepwholelist(L, &g->strt.hash[g->sweepstrgc + i]); |
| 1065 | g->sweepstrgc += i; |
| 1066 | if (g->sweepstrgc >= g->strt.size) /* no more strings to sweep? */ |
| 1067 | g->gcstate = GCSsweepudata; |
| 1068 | return i * GCSWEEPCOST; |
| 1069 | } |
| 1070 | case GCSsweepudata: { |
| 1071 | if (g->sweepfin) { |
| 1072 | g->sweepfin = sweeplist(L, g->sweepfin, GCSWEEPMAX); |
| 1073 | return GCSWEEPMAX*GCSWEEPCOST; |
| 1074 | } |
| 1075 | else { |
| 1076 | g->gcstate = GCSsweep; |
| 1077 | return 0; |
| 1078 | } |
| 1079 | } |
| 1080 | case GCSsweep: { |
| 1081 | if (g->sweepgc) { |
| 1082 | g->sweepgc = sweeplist(L, g->sweepgc, GCSWEEPMAX); |
| 1083 | return GCSWEEPMAX*GCSWEEPCOST; |
| 1084 | } |
| 1085 | else { |
| 1086 | /* sweep main thread */ |
| 1087 | GCObject *mt = obj2gco(g->mainthread); |
| 1088 | sweeplist(L, &mt, 1); |
| 1089 | checkSizes(L); |
| 1090 | g->gcstate = GCSpause; /* finish collection */ |
| 1091 | return GCSWEEPCOST; |
| 1092 | } |
| 1093 | } |
| 1094 | default: lua_assert(0); return 0; |
| 1095 | } |
| 1096 | } |
| 1097 | |
| 1098 | |
| 1099 | /* |
| 1100 | ** advances the garbage collector until it reaches a state allowed |
| 1101 | ** by 'statemask' |
| 1102 | */ |
| 1103 | void luaC_runtilstate (lua_State *L, int statesmask) { |
| 1104 | global_State *g = G(L); |
| 1105 | while (!testbit(statesmask, g->gcstate)) |
| 1106 | singlestep(L); |
| 1107 | } |
| 1108 | |
| 1109 | |
| 1110 | static void generationalcollection (lua_State *L) { |
| 1111 | global_State *g = G(L); |
| 1112 | lua_assert(g->gcstate == GCSpropagate); |
| 1113 | if (g->GCestimate == 0) { /* signal for another major collection? */ |
| 1114 | luaC_fullgc(L, 0); /* perform a full regular collection */ |
| 1115 | g->GCestimate = gettotalbytes(g); /* update control */ |
| 1116 | } |
| 1117 | else { |
| 1118 | lu_mem estimate = g->GCestimate; |
| 1119 | luaC_runtilstate(L, bitmask(GCSpause)); /* run complete (minor) cycle */ |
| 1120 | g->gcstate = GCSpropagate; /* skip restart */ |
| 1121 | if (gettotalbytes(g) > (estimate / 100) * g->gcmajorinc) |
| 1122 | g->GCestimate = 0; /* signal for a major collection */ |
| 1123 | else |
| 1124 | g->GCestimate = estimate; /* keep estimate from last major coll. */ |
| 1125 | |
| 1126 | } |
| 1127 | setpause(g, gettotalbytes(g)); |
| 1128 | lua_assert(g->gcstate == GCSpropagate); |
| 1129 | } |
| 1130 | |
| 1131 | |
| 1132 | static void incstep (lua_State *L) { |
| 1133 | global_State *g = G(L); |
| 1134 | l_mem debt = g->GCdebt; |
| 1135 | int stepmul = g->gcstepmul; |
| 1136 | if (stepmul < 40) stepmul = 40; /* avoid ridiculous low values (and 0) */ |
| 1137 | /* convert debt from Kb to 'work units' (avoid zero debt and overflows) */ |
| 1138 | debt = (debt / STEPMULADJ) + 1; |
| 1139 | debt = (debt < MAX_LMEM / stepmul) ? debt * stepmul : MAX_LMEM; |
| 1140 | do { /* always perform at least one single step */ |
| 1141 | lu_mem work = singlestep(L); /* do some work */ |
| 1142 | debt -= work; |
| 1143 | } while (debt > -GCSTEPSIZE && g->gcstate != GCSpause); |
| 1144 | if (g->gcstate == GCSpause) |
| 1145 | setpause(g, g->GCestimate); /* pause until next cycle */ |
| 1146 | else { |
| 1147 | debt = (debt / stepmul) * STEPMULADJ; /* convert 'work units' to Kb */ |
| 1148 | luaE_setdebt(g, debt); |
| 1149 | } |
| 1150 | } |
| 1151 | |
| 1152 | |
| 1153 | /* |
| 1154 | ** performs a basic GC step |
| 1155 | */ |
| 1156 | void luaC_forcestep (lua_State *L) { |
| 1157 | global_State *g = G(L); |
| 1158 | int i; |
| 1159 | if (isgenerational(g)) generationalcollection(L); |
| 1160 | else incstep(L); |
| 1161 | /* run a few finalizers (or all of them at the end of a collect cycle) */ |
| 1162 | for (i = 0; g->tobefnz && (i < GCFINALIZENUM || g->gcstate == GCSpause); i++) |
| 1163 | GCTM(L, 1); /* call one finalizer */ |
| 1164 | } |
| 1165 | |
| 1166 | |
| 1167 | /* |
| 1168 | ** performs a basic GC step only if collector is running |
| 1169 | */ |
| 1170 | void luaC_step (lua_State *L) { |
| 1171 | global_State *g = G(L); |
| 1172 | if (g->gcrunning) luaC_forcestep(L); |
| 1173 | else luaE_setdebt(g, -GCSTEPSIZE); /* avoid being called too often */ |
| 1174 | } |
| 1175 | |
| 1176 | |
| 1177 | |
| 1178 | /* |
| 1179 | ** performs a full GC cycle; if "isemergency", does not call |
| 1180 | ** finalizers (which could change stack positions) |
| 1181 | */ |
| 1182 | void luaC_fullgc (lua_State *L, int isemergency) { |
| 1183 | global_State *g = G(L); |
| 1184 | int origkind = g->gckind; |
| 1185 | lua_assert(origkind != KGC_EMERGENCY); |
| 1186 | if (isemergency) /* do not run finalizers during emergency GC */ |
| 1187 | g->gckind = KGC_EMERGENCY; |
| 1188 | else { |
| 1189 | g->gckind = KGC_NORMAL; |
| 1190 | callallpendingfinalizers(L, 1); |
| 1191 | } |
| 1192 | if (keepinvariant(g)) { /* may there be some black objects? */ |
| 1193 | /* must sweep all objects to turn them back to white |
| 1194 | (as white has not changed, nothing will be collected) */ |
| 1195 | entersweep(L); |
| 1196 | } |
| 1197 | /* finish any pending sweep phase to start a new cycle */ |
| 1198 | luaC_runtilstate(L, bitmask(GCSpause)); |
| 1199 | luaC_runtilstate(L, ~bitmask(GCSpause)); /* start new collection */ |
| 1200 | luaC_runtilstate(L, bitmask(GCSpause)); /* run entire collection */ |
| 1201 | if (origkind == KGC_GEN) { /* generational mode? */ |
| 1202 | /* generational mode must be kept in propagate phase */ |
| 1203 | luaC_runtilstate(L, bitmask(GCSpropagate)); |
| 1204 | } |
| 1205 | g->gckind = origkind; |
| 1206 | setpause(g, gettotalbytes(g)); |
| 1207 | if (!isemergency) /* do not run finalizers during emergency GC */ |
| 1208 | callallpendingfinalizers(L, 1); |
| 1209 | } |
| 1210 | |
| 1211 | /* }====================================================== */ |
| 1212 | |
| 1213 | |