ba8b5c17 |
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 | |