Line data Source code
1 : /*
2 : ** $Id: lgc.c,v 2.215.1.2 2017/08/31 16:15:27 roberto Exp $
3 : ** Garbage Collector
4 : ** See Copyright Notice in lua.h
5 : */
6 :
7 : #define lgc_c
8 : #define LUA_CORE
9 :
10 : #include "lprefix.h"
11 :
12 :
13 : #include <string.h>
14 :
15 : #include "lua.h"
16 :
17 : #include "ldebug.h"
18 : #include "ldo.h"
19 : #include "lfunc.h"
20 : #include "lgc.h"
21 : #include "lmem.h"
22 : #include "lobject.h"
23 : #include "lstate.h"
24 : #include "lstring.h"
25 : #include "ltable.h"
26 : #include "ltm.h"
27 :
28 :
29 : /*
30 : ** internal state for collector while inside the atomic phase. The
31 : ** collector should never be in this state while running regular code.
32 : */
33 : #define GCSinsideatomic (GCSpause + 1)
34 :
35 : /*
36 : ** cost of sweeping one element (the size of a small object divided
37 : ** by some adjust for the sweep speed)
38 : */
39 : #define GCSWEEPCOST ((sizeof(TString) + 4) / 4)
40 :
41 : /* maximum number of elements to sweep in each single step */
42 : #define GCSWEEPMAX (cast_int((GCSTEPSIZE / GCSWEEPCOST) / 4))
43 :
44 : /* cost of calling one finalizer */
45 : #define GCFINALIZECOST GCSWEEPCOST
46 :
47 :
48 : /*
49 : ** macro to adjust 'stepmul': 'stepmul' is actually used like
50 : ** 'stepmul / STEPMULADJ' (value chosen by tests)
51 : */
52 : #define STEPMULADJ 200
53 :
54 :
55 : /*
56 : ** macro to adjust 'pause': 'pause' is actually used like
57 : ** 'pause / PAUSEADJ' (value chosen by tests)
58 : */
59 : #define PAUSEADJ 100
60 :
61 :
62 : /*
63 : ** 'makewhite' erases all color bits then sets only the current white
64 : ** bit
65 : */
66 : #define maskcolors (~(bitmask(BLACKBIT) | WHITEBITS))
67 : #define makewhite(g,x) \
68 : (x->marked = cast_byte((x->marked & maskcolors) | luaC_white(g)))
69 :
70 : #define white2gray(x) resetbits(x->marked, WHITEBITS)
71 : #define black2gray(x) resetbit(x->marked, BLACKBIT)
72 :
73 :
74 : #define valiswhite(x) (iscollectable(x) && iswhite(gcvalue(x)))
75 :
76 : #define checkdeadkey(n) lua_assert(!ttisdeadkey(gkey(n)) || ttisnil(gval(n)))
77 :
78 :
79 : #define checkconsistency(obj) \
80 : lua_longassert(!iscollectable(obj) || righttt(obj))
81 :
82 :
83 : #define markvalue(g,o) { checkconsistency(o); \
84 : if (valiswhite(o)) reallymarkobject(g,gcvalue(o)); }
85 :
86 : #define markobject(g,t) { if (iswhite(t)) reallymarkobject(g, obj2gco(t)); }
87 :
88 : /*
89 : ** mark an object that can be NULL (either because it is really optional,
90 : ** or it was stripped as debug info, or inside an uncompleted structure)
91 : */
92 : #define markobjectN(g,t) { if (t) markobject(g,t); }
93 :
94 : static void reallymarkobject (global_State *g, GCObject *o);
95 :
96 :
97 : /*
98 : ** {======================================================
99 : ** Generic functions
100 : ** =======================================================
101 : */
102 :
103 :
104 : /*
105 : ** one after last element in a hash array
106 : */
107 : #define gnodelast(h) gnode(h, cast(size_t, sizenode(h)))
108 :
109 :
110 : /*
111 : ** link collectable object 'o' into list pointed by 'p'
112 : */
113 : #define linkgclist(o,p) ((o)->gclist = (p), (p) = obj2gco(o))
114 :
115 :
116 : /*
117 : ** If key is not marked, mark its entry as dead. This allows key to be
118 : ** collected, but keeps its entry in the table. A dead node is needed
119 : ** when Lua looks up for a key (it may be part of a chain) and when
120 : ** traversing a weak table (key might be removed from the table during
121 : ** traversal). Other places never manipulate dead keys, because its
122 : ** associated nil value is enough to signal that the entry is logically
123 : ** empty.
124 : */
125 20853 : static void removeentry (Node *n) {
126 : lua_assert(ttisnil(gval(n)));
127 20853 : if (valiswhite(gkey(n)))
128 1 : setdeadvalue(wgkey(n)); /* unused and unmarked key; remove it */
129 20853 : }
130 :
131 :
132 : /*
133 : ** tells whether a key or value can be cleared from a weak
134 : ** table. Non-collectable objects are never removed from weak
135 : ** tables. Strings behave as 'values', so are never removed too. for
136 : ** other objects: if really collected, cannot keep them; for objects
137 : ** being finalized, keep them in keys, but not in values
138 : */
139 0 : static int iscleared (global_State *g, const TValue *o) {
140 0 : if (!iscollectable(o)) return 0;
141 0 : else if (ttisstring(o)) {
142 0 : markobject(g, tsvalue(o)); /* strings are 'values', so are never weak */
143 0 : return 0;
144 : }
145 0 : else return iswhite(gcvalue(o));
146 : }
147 :
148 :
149 : /*
150 : ** barrier that moves collector forward, that is, mark the white object
151 : ** being pointed by a black object. (If in sweep phase, clear the black
152 : ** object to white [sweep it] to avoid other barrier calls for this
153 : ** same object.)
154 : */
155 879 : void luaC_barrier_ (lua_State *L, GCObject *o, GCObject *v) {
156 879 : global_State *g = G(L);
157 : lua_assert(isblack(o) && iswhite(v) && !isdead(g, v) && !isdead(g, o));
158 879 : if (keepinvariant(g)) /* must keep invariant? */
159 879 : reallymarkobject(g, v); /* restore invariant */
160 : else { /* sweep phase */
161 : lua_assert(issweepphase(g));
162 0 : makewhite(g, o); /* mark main obj. as white to avoid other barriers */
163 : }
164 879 : }
165 :
166 :
167 : /*
168 : ** barrier that moves collector backward, that is, mark the black object
169 : ** pointing to a white object as gray again.
170 : */
171 348 : void luaC_barrierback_ (lua_State *L, Table *t) {
172 348 : global_State *g = G(L);
173 : lua_assert(isblack(t) && !isdead(g, t));
174 348 : black2gray(t); /* make table gray (again) */
175 348 : linkgclist(t, g->grayagain);
176 348 : }
177 :
178 :
179 : /*
180 : ** barrier for assignments to closed upvalues. Because upvalues are
181 : ** shared among closures, it is impossible to know the color of all
182 : ** closures pointing to it. So, we assume that the object being assigned
183 : ** must be marked.
184 : */
185 4944 : void luaC_upvalbarrier_ (lua_State *L, UpVal *uv) {
186 4944 : global_State *g = G(L);
187 4944 : GCObject *o = gcvalue(uv->v);
188 : lua_assert(!upisopen(uv)); /* ensured by macro luaC_upvalbarrier */
189 4944 : if (keepinvariant(g))
190 1988 : markobject(g, o);
191 4944 : }
192 :
193 :
194 5088 : void luaC_fix (lua_State *L, GCObject *o) {
195 5088 : global_State *g = G(L);
196 : lua_assert(g->allgc == o); /* object must be 1st in 'allgc' list! */
197 5088 : white2gray(o); /* they will be gray forever */
198 5088 : g->allgc = o->next; /* remove object from 'allgc' list */
199 5088 : o->next = g->fixedgc; /* link it to 'fixedgc' list */
200 5088 : g->fixedgc = o;
201 5088 : }
202 :
203 :
204 : /*
205 : ** create a new collectable object (with given type and size) and link
206 : ** it to 'allgc' list.
207 : */
208 65929 : GCObject *luaC_newobj (lua_State *L, int tt, size_t sz) {
209 65929 : global_State *g = G(L);
210 65929 : GCObject *o = cast(GCObject *, luaM_newobject(L, novariant(tt), sz));
211 65929 : o->marked = luaC_white(g);
212 65929 : o->tt = tt;
213 65929 : o->next = g->allgc;
214 65929 : g->allgc = o;
215 65929 : return o;
216 : }
217 :
218 : /* }====================================================== */
219 :
220 :
221 :
222 : /*
223 : ** {======================================================
224 : ** Mark functions
225 : ** =======================================================
226 : */
227 :
228 :
229 : /*
230 : ** mark an object. Userdata, strings, and closed upvalues are visited
231 : ** and turned black here. Other objects are marked gray and added
232 : ** to appropriate list to be visited (and turned black) later. (Open
233 : ** upvalues are already linked in 'headuv' list.)
234 : */
235 46110 : static void reallymarkobject (global_State *g, GCObject *o) {
236 46110 : reentry:
237 46110 : white2gray(o);
238 46110 : switch (o->tt) {
239 34719 : case LUA_TSHRSTR: {
240 34719 : gray2black(o);
241 34719 : g->GCmemtrav += sizelstring(gco2ts(o)->shrlen);
242 34719 : break;
243 : }
244 1001 : case LUA_TLNGSTR: {
245 1001 : gray2black(o);
246 1001 : g->GCmemtrav += sizelstring(gco2ts(o)->u.lnglen);
247 1001 : break;
248 : }
249 483 : case LUA_TUSERDATA: {
250 : TValue uvalue;
251 483 : markobjectN(g, gco2u(o)->metatable); /* mark its metatable */
252 483 : gray2black(o);
253 483 : g->GCmemtrav += sizeudata(gco2u(o));
254 483 : getuservalue(g->mainthread, gco2u(o), &uvalue);
255 483 : if (valiswhite(&uvalue)) { /* markvalue(g, &uvalue); */
256 0 : o = gcvalue(&uvalue);
257 0 : goto reentry;
258 : }
259 483 : break;
260 : }
261 2278 : case LUA_TLCL: {
262 2278 : linkgclist(gco2lcl(o), g->gray);
263 2278 : break;
264 : }
265 784 : case LUA_TCCL: {
266 784 : linkgclist(gco2ccl(o), g->gray);
267 784 : break;
268 : }
269 3321 : case LUA_TTABLE: {
270 3321 : linkgclist(gco2t(o), g->gray);
271 3321 : break;
272 : }
273 280 : case LUA_TTHREAD: {
274 280 : linkgclist(gco2th(o), g->gray);
275 280 : break;
276 : }
277 3244 : case LUA_TPROTO: {
278 3244 : linkgclist(gco2p(o), g->gray);
279 3244 : break;
280 : }
281 0 : default: lua_assert(0); break;
282 : }
283 46110 : }
284 :
285 :
286 : /*
287 : ** mark metamethods for basic types
288 : */
289 510 : static void markmt (global_State *g) {
290 : int i;
291 5100 : for (i=0; i < LUA_NUMTAGS; i++)
292 4590 : markobjectN(g, g->mt[i]);
293 510 : }
294 :
295 :
296 : /*
297 : ** mark all objects in list of being-finalized
298 : */
299 510 : static void markbeingfnz (global_State *g) {
300 : GCObject *o;
301 516 : for (o = g->tobefnz; o != NULL; o = o->next)
302 6 : markobject(g, o);
303 510 : }
304 :
305 :
306 : /*
307 : ** Mark all values stored in marked open upvalues from non-marked threads.
308 : ** (Values from marked threads were already marked when traversing the
309 : ** thread.) Remove from the list threads that no longer have upvalues and
310 : ** not-marked threads.
311 : */
312 245 : static void remarkupvals (global_State *g) {
313 : lua_State *thread;
314 245 : lua_State **p = &g->twups;
315 285 : while ((thread = *p) != NULL) {
316 : lua_assert(!isblack(thread)); /* threads are never black */
317 40 : if (isgray(thread) && thread->openupval != NULL)
318 21 : p = &thread->twups; /* keep marked thread with upvalues in the list */
319 : else { /* thread is not marked or without upvalues */
320 : UpVal *uv;
321 19 : *p = thread->twups; /* remove thread from the list */
322 19 : thread->twups = thread; /* mark that it is out of list */
323 19 : for (uv = thread->openupval; uv != NULL; uv = uv->u.open.next) {
324 0 : if (uv->u.open.touched) {
325 0 : markvalue(g, uv->v); /* remark upvalue's value */
326 0 : uv->u.open.touched = 0;
327 : }
328 : }
329 : }
330 : }
331 245 : }
332 :
333 :
334 : /*
335 : ** mark root set and reset all gray lists, to start a new collection
336 : */
337 265 : static void restartcollection (global_State *g) {
338 265 : g->gray = g->grayagain = NULL;
339 265 : g->weak = g->allweak = g->ephemeron = NULL;
340 265 : markobject(g, g->mainthread);
341 265 : markvalue(g, &g->l_registry);
342 265 : markmt(g);
343 265 : markbeingfnz(g); /* mark any finalizing object left from previous cycle */
344 265 : }
345 :
346 : /* }====================================================== */
347 :
348 :
349 : /*
350 : ** {======================================================
351 : ** Traverse functions
352 : ** =======================================================
353 : */
354 :
355 : /*
356 : ** Traverse a table with weak values and link it to proper list. During
357 : ** propagate phase, keep it in 'grayagain' list, to be revisited in the
358 : ** atomic phase. In the atomic phase, if table has any white value,
359 : ** put it in 'weak' list, to be cleared.
360 : */
361 0 : static void traverseweakvalue (global_State *g, Table *h) {
362 0 : Node *n, *limit = gnodelast(h);
363 : /* if there is array part, assume it may have white values (it is not
364 : worth traversing it now just to check) */
365 0 : int hasclears = (h->sizearray > 0);
366 0 : for (n = gnode(h, 0); n < limit; n++) { /* traverse hash part */
367 : checkdeadkey(n);
368 0 : if (ttisnil(gval(n))) /* entry is empty? */
369 0 : removeentry(n); /* remove it */
370 : else {
371 : lua_assert(!ttisnil(gkey(n)));
372 0 : markvalue(g, gkey(n)); /* mark key */
373 0 : if (!hasclears && iscleared(g, gval(n))) /* is there a white value? */
374 0 : hasclears = 1; /* table will have to be cleared */
375 : }
376 : }
377 0 : if (g->gcstate == GCSpropagate)
378 0 : linkgclist(h, g->grayagain); /* must retraverse it in atomic phase */
379 0 : else if (hasclears)
380 0 : linkgclist(h, g->weak); /* has to be cleared later */
381 0 : }
382 :
383 :
384 : /*
385 : ** Traverse an ephemeron table and link it to proper list. Returns true
386 : ** iff any object was marked during this traversal (which implies that
387 : ** convergence has to continue). During propagation phase, keep table
388 : ** in 'grayagain' list, to be visited again in the atomic phase. In
389 : ** the atomic phase, if table has any white->white entry, it has to
390 : ** be revisited during ephemeron convergence (as that key may turn
391 : ** black). Otherwise, if it has any white key, table has to be cleared
392 : ** (in the atomic phase).
393 : */
394 0 : static int traverseephemeron (global_State *g, Table *h) {
395 0 : int marked = 0; /* true if an object is marked in this traversal */
396 0 : int hasclears = 0; /* true if table has white keys */
397 0 : int hasww = 0; /* true if table has entry "white-key -> white-value" */
398 0 : Node *n, *limit = gnodelast(h);
399 : unsigned int i;
400 : /* traverse array part */
401 0 : for (i = 0; i < h->sizearray; i++) {
402 0 : if (valiswhite(&h->array[i])) {
403 0 : marked = 1;
404 0 : reallymarkobject(g, gcvalue(&h->array[i]));
405 : }
406 : }
407 : /* traverse hash part */
408 0 : for (n = gnode(h, 0); n < limit; n++) {
409 : checkdeadkey(n);
410 0 : if (ttisnil(gval(n))) /* entry is empty? */
411 0 : removeentry(n); /* remove it */
412 0 : else if (iscleared(g, gkey(n))) { /* key is not marked (yet)? */
413 0 : hasclears = 1; /* table must be cleared */
414 0 : if (valiswhite(gval(n))) /* value not marked yet? */
415 0 : hasww = 1; /* white-white entry */
416 : }
417 0 : else if (valiswhite(gval(n))) { /* value not marked yet? */
418 0 : marked = 1;
419 0 : reallymarkobject(g, gcvalue(gval(n))); /* mark it now */
420 : }
421 : }
422 : /* link table into proper list */
423 0 : if (g->gcstate == GCSpropagate)
424 0 : linkgclist(h, g->grayagain); /* must retraverse it in atomic phase */
425 0 : else if (hasww) /* table has white->white entries? */
426 0 : linkgclist(h, g->ephemeron); /* have to propagate again */
427 0 : else if (hasclears) /* table has white keys? */
428 0 : linkgclist(h, g->allweak); /* may have to clean white keys */
429 0 : return marked;
430 : }
431 :
432 :
433 3589 : static void traversestrongtable (global_State *g, Table *h) {
434 3589 : Node *n, *limit = gnodelast(h);
435 : unsigned int i;
436 6449 : for (i = 0; i < h->sizearray; i++) /* traverse array part */
437 2860 : markvalue(g, &h->array[i]);
438 62671 : for (n = gnode(h, 0); n < limit; n++) { /* traverse hash part */
439 : checkdeadkey(n);
440 59082 : if (ttisnil(gval(n))) /* entry is empty? */
441 20853 : removeentry(n); /* remove it */
442 : else {
443 : lua_assert(!ttisnil(gkey(n)));
444 38229 : markvalue(g, gkey(n)); /* mark key */
445 38229 : markvalue(g, gval(n)); /* mark value */
446 : }
447 : }
448 3589 : }
449 :
450 :
451 3589 : static lu_mem traversetable (global_State *g, Table *h) {
452 : const char *weakkey, *weakvalue;
453 3589 : const TValue *mode = gfasttm(g, h->metatable, TM_MODE);
454 3589 : markobjectN(g, h->metatable);
455 3589 : if (mode && ttisstring(mode) && /* is there a weak mode? */
456 0 : ((weakkey = strchr(svalue(mode), 'k')),
457 0 : (weakvalue = strchr(svalue(mode), 'v')),
458 0 : (weakkey || weakvalue))) { /* is really weak? */
459 0 : black2gray(h); /* keep table gray */
460 0 : if (!weakkey) /* strong keys? */
461 0 : traverseweakvalue(g, h);
462 0 : else if (!weakvalue) /* strong values? */
463 0 : traverseephemeron(g, h);
464 : else /* all weak */
465 0 : linkgclist(h, g->allweak); /* nothing to traverse now */
466 : }
467 : else /* not weak */
468 3589 : traversestrongtable(g, h);
469 3589 : return sizeof(Table) + sizeof(TValue) * h->sizearray +
470 3589 : sizeof(Node) * cast(size_t, allocsizenode(h));
471 : }
472 :
473 :
474 : /*
475 : ** Traverse a prototype. (While a prototype is being build, its
476 : ** arrays can be larger than needed; the extra slots are filled with
477 : ** NULL, so the use of 'markobjectN')
478 : */
479 3125 : static int traverseproto (global_State *g, Proto *f) {
480 : int i;
481 3125 : if (f->cache && iswhite(f->cache))
482 513 : f->cache = NULL; /* allow cache to be collected */
483 3125 : markobjectN(g, f->source);
484 23534 : for (i = 0; i < f->sizek; i++) /* mark literals */
485 20409 : markvalue(g, &f->k[i]);
486 8524 : for (i = 0; i < f->sizeupvalues; i++) /* mark upvalue names */
487 5399 : markobjectN(g, f->upvalues[i].name);
488 5536 : for (i = 0; i < f->sizep; i++) /* mark nested protos */
489 2411 : markobjectN(g, f->p[i]);
490 11870 : for (i = 0; i < f->sizelocvars; i++) /* mark local-variable names */
491 8745 : markobjectN(g, f->locvars[i].varname);
492 3125 : return sizeof(Proto) + sizeof(Instruction) * f->sizecode +
493 3125 : sizeof(Proto *) * f->sizep +
494 3125 : sizeof(TValue) * f->sizek +
495 3125 : sizeof(int) * f->sizelineinfo +
496 6250 : sizeof(LocVar) * f->sizelocvars +
497 3125 : sizeof(Upvaldesc) * f->sizeupvalues;
498 : }
499 :
500 :
501 783 : static lu_mem traverseCclosure (global_State *g, CClosure *cl) {
502 : int i;
503 1574 : for (i = 0; i < cl->nupvalues; i++) /* mark its upvalues */
504 791 : markvalue(g, &cl->upvalue[i]);
505 783 : return sizeCclosure(cl->nupvalues);
506 : }
507 :
508 : /*
509 : ** open upvalues point to values in a thread, so those values should
510 : ** be marked when the thread is traversed except in the atomic phase
511 : ** (because then the value cannot be changed by the thread and the
512 : ** thread may not be traversed again)
513 : */
514 2235 : static lu_mem traverseLclosure (global_State *g, LClosure *cl) {
515 : int i;
516 2235 : markobjectN(g, cl->p); /* mark its prototype */
517 10260 : for (i = 0; i < cl->nupvalues; i++) { /* mark its upvalues */
518 8025 : UpVal *uv = cl->upvals[i];
519 8025 : if (uv != NULL) {
520 7999 : if (upisopen(uv) && g->gcstate != GCSinsideatomic)
521 1143 : uv->u.open.touched = 1; /* can be marked in 'remarkupvals' */
522 : else
523 6856 : markvalue(g, uv->v);
524 : }
525 : }
526 2235 : return sizeLclosure(cl->nupvalues);
527 : }
528 :
529 :
530 531 : static lu_mem traversethread (global_State *g, lua_State *th) {
531 531 : StkId o = th->stack;
532 531 : if (o == NULL)
533 0 : return 1; /* stack not completely built yet */
534 : lua_assert(g->gcstate == GCSinsideatomic ||
535 : th->openupval == NULL || isintwups(th));
536 8920 : for (; o < th->top; o++) /* mark live elements in the stack */
537 8389 : markvalue(g, o);
538 531 : if (g->gcstate == GCSinsideatomic) { /* final traversal? */
539 259 : StkId lim = th->stack + th->stacksize; /* real end of stack */
540 10150 : for (; o < lim; o++) /* clear not-marked stack slice */
541 9891 : setnilvalue(o);
542 : /* 'remarkupvals' may have removed thread from 'twups' list */
543 259 : if (!isintwups(th) && th->openupval != NULL) {
544 0 : th->twups = g->twups; /* link it back to the list */
545 0 : g->twups = th;
546 : }
547 : }
548 272 : else if (g->gckind != KGC_EMERGENCY)
549 272 : luaD_shrinkstack(th); /* do not change stack in emergency cycle */
550 531 : return (sizeof(lua_State) + sizeof(TValue) * th->stacksize +
551 531 : sizeof(CallInfo) * th->nci);
552 : }
553 :
554 :
555 : /*
556 : ** traverse one gray object, turning it to black (except for threads,
557 : ** which are always gray).
558 : */
559 10263 : static void propagatemark (global_State *g) {
560 : lu_mem size;
561 10263 : GCObject *o = g->gray;
562 : lua_assert(isgray(o));
563 10263 : gray2black(o);
564 10263 : switch (o->tt) {
565 3589 : case LUA_TTABLE: {
566 3589 : Table *h = gco2t(o);
567 3589 : g->gray = h->gclist; /* remove from 'gray' list */
568 3589 : size = traversetable(g, h);
569 3589 : break;
570 : }
571 2235 : case LUA_TLCL: {
572 2235 : LClosure *cl = gco2lcl(o);
573 2235 : g->gray = cl->gclist; /* remove from 'gray' list */
574 2235 : size = traverseLclosure(g, cl);
575 2235 : break;
576 : }
577 783 : case LUA_TCCL: {
578 783 : CClosure *cl = gco2ccl(o);
579 783 : g->gray = cl->gclist; /* remove from 'gray' list */
580 783 : size = traverseCclosure(g, cl);
581 783 : break;
582 : }
583 531 : case LUA_TTHREAD: {
584 531 : lua_State *th = gco2th(o);
585 531 : g->gray = th->gclist; /* remove from 'gray' list */
586 531 : linkgclist(th, g->grayagain); /* insert into 'grayagain' list */
587 531 : black2gray(o);
588 531 : size = traversethread(g, th);
589 531 : break;
590 : }
591 3125 : case LUA_TPROTO: {
592 3125 : Proto *p = gco2p(o);
593 3125 : g->gray = p->gclist; /* remove from 'gray' list */
594 3125 : size = traverseproto(g, p);
595 3125 : break;
596 : }
597 0 : default: lua_assert(0); return;
598 : }
599 10263 : g->GCmemtrav += size;
600 : }
601 :
602 :
603 980 : static void propagateall (global_State *g) {
604 2755 : while (g->gray) propagatemark(g);
605 980 : }
606 :
607 :
608 490 : static void convergeephemerons (global_State *g) {
609 : int changed;
610 : do {
611 : GCObject *w;
612 490 : GCObject *next = g->ephemeron; /* get ephemeron list */
613 490 : g->ephemeron = NULL; /* tables may return to this list when traversed */
614 490 : changed = 0;
615 490 : while ((w = next) != NULL) {
616 0 : next = gco2t(w)->gclist;
617 0 : if (traverseephemeron(g, gco2t(w))) { /* traverse marked some value? */
618 0 : propagateall(g); /* propagate changes */
619 0 : changed = 1; /* will have to revisit all ephemeron tables */
620 : }
621 : }
622 490 : } while (changed);
623 490 : }
624 :
625 : /* }====================================================== */
626 :
627 :
628 : /*
629 : ** {======================================================
630 : ** Sweep Functions
631 : ** =======================================================
632 : */
633 :
634 :
635 : /*
636 : ** clear entries with unmarked keys from all weaktables in list 'l' up
637 : ** to element 'f'
638 : */
639 490 : static void clearkeys (global_State *g, GCObject *l, GCObject *f) {
640 490 : for (; l != f; l = gco2t(l)->gclist) {
641 0 : Table *h = gco2t(l);
642 0 : Node *n, *limit = gnodelast(h);
643 0 : for (n = gnode(h, 0); n < limit; n++) {
644 0 : if (!ttisnil(gval(n)) && (iscleared(g, gkey(n)))) {
645 0 : setnilvalue(gval(n)); /* remove value ... */
646 : }
647 0 : if (ttisnil(gval(n))) /* is entry empty? */
648 0 : removeentry(n); /* remove entry from table */
649 : }
650 : }
651 490 : }
652 :
653 :
654 : /*
655 : ** clear entries with unmarked values from all weaktables in list 'l' up
656 : ** to element 'f'
657 : */
658 980 : static void clearvalues (global_State *g, GCObject *l, GCObject *f) {
659 980 : for (; l != f; l = gco2t(l)->gclist) {
660 0 : Table *h = gco2t(l);
661 0 : Node *n, *limit = gnodelast(h);
662 : unsigned int i;
663 0 : for (i = 0; i < h->sizearray; i++) {
664 0 : TValue *o = &h->array[i];
665 0 : if (iscleared(g, o)) /* value was collected? */
666 0 : setnilvalue(o); /* remove value */
667 : }
668 0 : for (n = gnode(h, 0); n < limit; n++) {
669 0 : if (!ttisnil(gval(n)) && iscleared(g, gval(n))) {
670 0 : setnilvalue(gval(n)); /* remove value ... */
671 0 : removeentry(n); /* and remove entry from table */
672 : }
673 : }
674 : }
675 980 : }
676 :
677 :
678 9942 : void luaC_upvdeccount (lua_State *L, UpVal *uv) {
679 : lua_assert(uv->refcount > 0);
680 9942 : uv->refcount--;
681 9942 : if (uv->refcount == 0 && !upisopen(uv))
682 6049 : luaM_free(L, uv);
683 9942 : }
684 :
685 :
686 3342 : static void freeLclosure (lua_State *L, LClosure *cl) {
687 : int i;
688 13325 : for (i = 0; i < cl->nupvalues; i++) {
689 9983 : UpVal *uv = cl->upvals[i];
690 9983 : if (uv)
691 9942 : luaC_upvdeccount(L, uv);
692 : }
693 3342 : luaM_freemem(L, cl, sizeLclosure(cl->nupvalues));
694 3342 : }
695 :
696 :
697 61516 : static void freeobj (lua_State *L, GCObject *o) {
698 61516 : switch (o->tt) {
699 2182 : case LUA_TPROTO: luaF_freeproto(L, gco2p(o)); break;
700 3342 : case LUA_TLCL: {
701 3342 : freeLclosure(L, gco2lcl(o));
702 3342 : break;
703 : }
704 404 : case LUA_TCCL: {
705 404 : luaM_freemem(L, o, sizeCclosure(gco2ccl(o)->nupvalues));
706 404 : break;
707 : }
708 8663 : case LUA_TTABLE: luaH_free(L, gco2t(o)); break;
709 27 : case LUA_TTHREAD: luaE_freethread(L, gco2th(o)); break;
710 371 : case LUA_TUSERDATA: luaM_freemem(L, o, sizeudata(gco2u(o))); break;
711 41908 : case LUA_TSHRSTR:
712 41908 : luaS_remove(L, gco2ts(o)); /* remove it from hash table */
713 41908 : luaM_freemem(L, o, sizelstring(gco2ts(o)->shrlen));
714 41908 : break;
715 4619 : case LUA_TLNGSTR: {
716 4619 : luaM_freemem(L, o, sizelstring(gco2ts(o)->u.lnglen));
717 4619 : break;
718 : }
719 61516 : default: lua_assert(0);
720 : }
721 61516 : }
722 :
723 :
724 : #define sweepwholelist(L,p) sweeplist(L,p,MAX_LUMEM)
725 : static GCObject **sweeplist (lua_State *L, GCObject **p, lu_mem count);
726 :
727 :
728 : /*
729 : ** sweep at most 'count' elements from a list of GCObjects erasing dead
730 : ** objects, where a dead object is one marked with the old (non current)
731 : ** white; change all non-dead objects back to white, preparing for next
732 : ** collection cycle. Return where to continue the traversal or NULL if
733 : ** list is finished.
734 : */
735 1880 : static GCObject **sweeplist (lua_State *L, GCObject **p, lu_mem count) {
736 1880 : global_State *g = G(L);
737 1880 : int ow = otherwhite(g);
738 1880 : int white = luaC_white(g); /* current white */
739 103339 : while (*p != NULL && count-- > 0) {
740 101459 : GCObject *curr = *p;
741 101459 : int marked = curr->marked;
742 101459 : if (isdeadm(ow, marked)) { /* is 'curr' dead? */
743 61516 : *p = curr->next; /* remove 'curr' from list */
744 61516 : freeobj(L, curr); /* erase 'curr' */
745 : }
746 : else { /* change mark to 'white' */
747 39943 : curr->marked = cast_byte((marked & maskcolors) | white);
748 39943 : p = &curr->next; /* go to next element */
749 : }
750 : }
751 1880 : return (*p == NULL) ? NULL : p;
752 : }
753 :
754 :
755 : /*
756 : ** sweep a list until a live object (or end of list)
757 : */
758 0 : static GCObject **sweeptolive (lua_State *L, GCObject **p) {
759 0 : GCObject **old = p;
760 : do {
761 0 : p = sweeplist(L, p, 1);
762 0 : } while (p == old);
763 0 : return p;
764 : }
765 :
766 : /* }====================================================== */
767 :
768 :
769 : /*
770 : ** {======================================================
771 : ** Finalization
772 : ** =======================================================
773 : */
774 :
775 : /*
776 : ** If possible, shrink string table
777 : */
778 245 : static void checkSizes (lua_State *L, global_State *g) {
779 245 : if (g->gckind != KGC_EMERGENCY) {
780 245 : l_mem olddebt = g->GCdebt;
781 245 : if (g->strt.nuse < g->strt.size / 4) /* string table too big? */
782 11 : luaS_resize(L, g->strt.size / 2); /* shrink it a little */
783 245 : g->GCestimate += g->GCdebt - olddebt; /* update estimate */
784 : }
785 245 : }
786 :
787 :
788 444 : static GCObject *udata2finalize (global_State *g) {
789 444 : GCObject *o = g->tobefnz; /* get first element */
790 : lua_assert(tofinalize(o));
791 444 : g->tobefnz = o->next; /* remove it from 'tobefnz' list */
792 444 : o->next = g->allgc; /* return it to 'allgc' list */
793 444 : g->allgc = o;
794 444 : resetbit(o->marked, FINALIZEDBIT); /* object is "normal" again */
795 444 : if (issweepphase(g))
796 9 : makewhite(g, o); /* "sweep" object */
797 444 : return o;
798 : }
799 :
800 :
801 444 : static void dothecall (lua_State *L, void *ud) {
802 : UNUSED(ud);
803 444 : luaD_callnoyield(L, L->top - 2, 0);
804 444 : }
805 :
806 :
807 444 : static void GCTM (lua_State *L, int propagateerrors) {
808 444 : global_State *g = G(L);
809 : const TValue *tm;
810 : TValue v;
811 444 : setgcovalue(L, &v, udata2finalize(g));
812 444 : tm = luaT_gettmbyobj(L, &v, TM_GC);
813 444 : if (tm != NULL && ttisfunction(tm)) { /* is there a finalizer? */
814 : int status;
815 444 : lu_byte oldah = L->allowhook;
816 444 : int running = g->gcrunning;
817 444 : L->allowhook = 0; /* stop debug hooks during GC metamethod */
818 444 : g->gcrunning = 0; /* avoid GC steps */
819 444 : setobj2s(L, L->top, tm); /* push finalizer... */
820 444 : setobj2s(L, L->top + 1, &v); /* ... and its argument */
821 444 : L->top += 2; /* and (next line) call the finalizer */
822 444 : L->ci->callstatus |= CIST_FIN; /* will run a finalizer */
823 444 : status = luaD_pcall(L, dothecall, NULL, savestack(L, L->top - 2), 0);
824 444 : L->ci->callstatus &= ~CIST_FIN; /* not running a finalizer anymore */
825 444 : L->allowhook = oldah; /* restore hooks */
826 444 : g->gcrunning = running; /* restore state */
827 444 : if (status != LUA_OK && propagateerrors) { /* error while running __gc? */
828 0 : if (status == LUA_ERRRUN) { /* is there an error object? */
829 0 : const char *msg = (ttisstring(L->top - 1))
830 0 : ? svalue(L->top - 1)
831 0 : : "no message";
832 0 : luaO_pushfstring(L, "error in __gc metamethod (%s)", msg);
833 0 : status = LUA_ERRGCMM; /* error in __gc metamethod */
834 : }
835 0 : luaD_throw(L, status); /* re-throw error */
836 : }
837 : }
838 444 : }
839 :
840 :
841 : /*
842 : ** call a few (up to 'g->gcfinnum') finalizers
843 : */
844 936 : static int runafewfinalizers (lua_State *L) {
845 936 : global_State *g = G(L);
846 : unsigned int i;
847 : lua_assert(!g->tobefnz || g->gcfinnum > 0);
848 942 : for (i = 0; g->tobefnz && i < g->gcfinnum; i++)
849 6 : GCTM(L, 1); /* call one finalizer */
850 1872 : g->gcfinnum = (!g->tobefnz) ? 0 /* nothing more to finalize? */
851 936 : : g->gcfinnum * 2; /* else call a few more next time */
852 936 : return i;
853 : }
854 :
855 :
856 : /*
857 : ** call all pending finalizers
858 : */
859 88 : static void callallpendingfinalizers (lua_State *L) {
860 88 : global_State *g = G(L);
861 526 : while (g->tobefnz)
862 438 : GCTM(L, 0);
863 88 : }
864 :
865 :
866 : /*
867 : ** find last 'next' field in list 'p' list (to add elements in its end)
868 : */
869 333 : static GCObject **findlast (GCObject **p) {
870 333 : while (*p != NULL)
871 0 : p = &(*p)->next;
872 333 : return p;
873 : }
874 :
875 :
876 : /*
877 : ** move all unreachable objects (or 'all' objects) that need
878 : ** finalization from list 'finobj' to list 'tobefnz' (to be finalized)
879 : */
880 333 : static void separatetobefnz (global_State *g, int all) {
881 : GCObject *curr;
882 333 : GCObject **p = &g->finobj;
883 333 : GCObject **lastnext = findlast(&g->tobefnz);
884 1341 : while ((curr = *p) != NULL) { /* traverse all finalizable objects */
885 : lua_assert(tofinalize(curr));
886 1008 : if (!(iswhite(curr) || all)) /* not being collected? */
887 564 : p = &curr->next; /* don't bother with it */
888 : else {
889 444 : *p = curr->next; /* remove 'curr' from 'finobj' list */
890 444 : curr->next = *lastnext; /* link at the end of 'tobefnz' list */
891 444 : *lastnext = curr;
892 444 : lastnext = &curr->next;
893 : }
894 : }
895 333 : }
896 :
897 :
898 : /*
899 : ** if object 'o' has a finalizer, remove it from 'allgc' list (must
900 : ** search the list to find it) and link it in 'finobj' list.
901 : */
902 577 : void luaC_checkfinalizer (lua_State *L, GCObject *o, Table *mt) {
903 577 : global_State *g = G(L);
904 577 : if (tofinalize(o) || /* obj. is already marked... */
905 577 : gfasttm(g, mt, TM_GC) == NULL) /* or has no finalizer? */
906 97 : return; /* nothing to be done */
907 : else { /* move 'o' to 'finobj' list */
908 : GCObject **p;
909 480 : if (issweepphase(g)) {
910 3 : makewhite(g, o); /* "sweep" object 'o' */
911 3 : if (g->sweepgc == &o->next) /* should not remove 'sweepgc' object */
912 0 : g->sweepgc = sweeptolive(L, g->sweepgc); /* change 'sweepgc' */
913 : }
914 : /* search for pointer pointing to 'o' */
915 568 : for (p = &g->allgc; *p != o; p = &(*p)->next) { /* empty */ }
916 480 : *p = o->next; /* remove 'o' from 'allgc' list */
917 480 : o->next = g->finobj; /* link it in 'finobj' list */
918 480 : g->finobj = o;
919 480 : l_setbit(o->marked, FINALIZEDBIT); /* mark it as such */
920 : }
921 : }
922 :
923 : /* }====================================================== */
924 :
925 :
926 :
927 : /*
928 : ** {======================================================
929 : ** GC control
930 : ** =======================================================
931 : */
932 :
933 :
934 : /*
935 : ** Set a reasonable "time" to wait before starting a new GC cycle; cycle
936 : ** will start when memory use hits threshold. (Division by 'estimate'
937 : ** should be OK: it cannot be zero (because Lua cannot even start with
938 : ** less than PAUSEADJ bytes).
939 : */
940 244 : static void setpause (global_State *g) {
941 : l_mem threshold, debt;
942 244 : l_mem estimate = g->GCestimate / PAUSEADJ; /* adjust 'estimate' */
943 : lua_assert(estimate > 0);
944 488 : threshold = (g->gcpause < MAX_LMEM / estimate) /* overflow? */
945 244 : ? estimate * g->gcpause /* no overflow */
946 244 : : MAX_LMEM; /* overflow; truncate to maximum */
947 244 : debt = gettotalbytes(g) - threshold;
948 244 : luaE_setdebt(g, debt);
949 244 : }
950 :
951 :
952 : /*
953 : ** Enter first sweep phase.
954 : ** The call to 'sweeplist' tries to make pointer point to an object
955 : ** inside the list (instead of to the header), so that the real sweep do
956 : ** not need to skip objects created between "now" and the start of the
957 : ** real sweep.
958 : */
959 246 : static void entersweep (lua_State *L) {
960 246 : global_State *g = G(L);
961 246 : g->gcstate = GCSswpallgc;
962 : lua_assert(g->sweepgc == NULL);
963 246 : g->sweepgc = sweeplist(L, &g->allgc, 1);
964 246 : }
965 :
966 :
967 88 : void luaC_freeallobjects (lua_State *L) {
968 88 : global_State *g = G(L);
969 88 : separatetobefnz(g, 1); /* separate all objects with finalizers */
970 : lua_assert(g->finobj == NULL);
971 88 : callallpendingfinalizers(L);
972 : lua_assert(g->tobefnz == NULL);
973 88 : g->currentwhite = WHITEBITS; /* this "white" makes all objects look dead */
974 88 : g->gckind = KGC_NORMAL;
975 88 : sweepwholelist(L, &g->finobj);
976 88 : sweepwholelist(L, &g->allgc);
977 88 : sweepwholelist(L, &g->fixedgc); /* collect fixed objects */
978 : lua_assert(g->strt.nuse == 0);
979 88 : }
980 :
981 :
982 245 : static l_mem atomic (lua_State *L) {
983 245 : global_State *g = G(L);
984 : l_mem work;
985 : GCObject *origweak, *origall;
986 245 : GCObject *grayagain = g->grayagain; /* save original list */
987 : lua_assert(g->ephemeron == NULL && g->weak == NULL);
988 : lua_assert(!iswhite(g->mainthread));
989 245 : g->gcstate = GCSinsideatomic;
990 245 : g->GCmemtrav = 0; /* start counting work */
991 245 : markobject(g, L); /* mark running thread */
992 : /* registry and global metatables may be changed by API */
993 245 : markvalue(g, &g->l_registry);
994 245 : markmt(g); /* mark global metatables */
995 : /* remark occasional upvalues of (maybe) dead threads */
996 245 : remarkupvals(g);
997 245 : propagateall(g); /* propagate changes */
998 245 : work = g->GCmemtrav; /* stop counting (do not recount 'grayagain') */
999 245 : g->gray = grayagain;
1000 245 : propagateall(g); /* traverse 'grayagain' list */
1001 245 : g->GCmemtrav = 0; /* restart counting */
1002 245 : convergeephemerons(g);
1003 : /* at this point, all strongly accessible objects are marked. */
1004 : /* Clear values from weak tables, before checking finalizers */
1005 245 : clearvalues(g, g->weak, NULL);
1006 245 : clearvalues(g, g->allweak, NULL);
1007 245 : origweak = g->weak; origall = g->allweak;
1008 245 : work += g->GCmemtrav; /* stop counting (objects being finalized) */
1009 245 : separatetobefnz(g, 0); /* separate objects to be finalized */
1010 245 : g->gcfinnum = 1; /* there may be objects to be finalized */
1011 245 : markbeingfnz(g); /* mark objects that will be finalized */
1012 245 : propagateall(g); /* remark, to propagate 'resurrection' */
1013 245 : g->GCmemtrav = 0; /* restart counting */
1014 245 : convergeephemerons(g);
1015 : /* at this point, all resurrected objects are marked. */
1016 : /* remove dead objects from weak tables */
1017 245 : clearkeys(g, g->ephemeron, NULL); /* clear keys from all ephemeron tables */
1018 245 : clearkeys(g, g->allweak, NULL); /* clear keys from all 'allweak' tables */
1019 : /* clear values from resurrected weak tables */
1020 245 : clearvalues(g, g->weak, origweak);
1021 245 : clearvalues(g, g->allweak, origall);
1022 245 : luaS_clearcache(g);
1023 245 : g->currentwhite = cast_byte(otherwhite(g)); /* flip current white */
1024 245 : work += g->GCmemtrav; /* complete counting */
1025 245 : return work; /* estimate of memory marked by 'atomic' */
1026 : }
1027 :
1028 :
1029 1370 : static lu_mem sweepstep (lua_State *L, global_State *g,
1030 : int nextstate, GCObject **nextlist) {
1031 1370 : if (g->sweepgc) {
1032 1370 : l_mem olddebt = g->GCdebt;
1033 1370 : g->sweepgc = sweeplist(L, g->sweepgc, GCSWEEPMAX);
1034 1370 : g->GCestimate += g->GCdebt - olddebt; /* update estimate */
1035 1370 : if (g->sweepgc) /* is there still something to sweep? */
1036 635 : return (GCSWEEPMAX * GCSWEEPCOST);
1037 : }
1038 : /* else enter next state */
1039 735 : g->gcstate = nextstate;
1040 735 : g->sweepgc = nextlist;
1041 735 : return 0;
1042 : }
1043 :
1044 :
1045 10859 : static lu_mem singlestep (lua_State *L) {
1046 10859 : global_State *g = G(L);
1047 10859 : switch (g->gcstate) {
1048 265 : case GCSpause: {
1049 265 : g->GCmemtrav = g->strt.size * sizeof(GCObject*);
1050 265 : restartcollection(g);
1051 265 : g->gcstate = GCSpropagate;
1052 265 : return g->GCmemtrav;
1053 : }
1054 8488 : case GCSpropagate: {
1055 8488 : g->GCmemtrav = 0;
1056 : lua_assert(g->gray);
1057 8488 : propagatemark(g);
1058 8488 : if (g->gray == NULL) /* no more gray objects? */
1059 246 : g->gcstate = GCSatomic; /* finish propagate phase */
1060 8488 : return g->GCmemtrav; /* memory traversed in this step */
1061 : }
1062 245 : case GCSatomic: {
1063 : lu_mem work;
1064 245 : propagateall(g); /* make sure gray list is empty */
1065 245 : work = atomic(L); /* work is what was traversed by 'atomic' */
1066 245 : entersweep(L);
1067 245 : g->GCestimate = gettotalbytes(g); /* first estimate */;
1068 245 : return work;
1069 : }
1070 880 : case GCSswpallgc: { /* sweep "regular" objects */
1071 880 : return sweepstep(L, g, GCSswpfinobj, &g->finobj);
1072 : }
1073 245 : case GCSswpfinobj: { /* sweep objects with finalizers */
1074 245 : return sweepstep(L, g, GCSswptobefnz, &g->tobefnz);
1075 : }
1076 245 : case GCSswptobefnz: { /* sweep objects to be finalized */
1077 245 : return sweepstep(L, g, GCSswpend, NULL);
1078 : }
1079 245 : case GCSswpend: { /* finish sweeps */
1080 245 : makewhite(g, g->mainthread); /* sweep main thread */
1081 245 : checkSizes(L, g);
1082 245 : g->gcstate = GCScallfin;
1083 245 : return 0;
1084 : }
1085 246 : case GCScallfin: { /* call remaining finalizers */
1086 246 : if (g->tobefnz && g->gckind != KGC_EMERGENCY) {
1087 1 : int n = runafewfinalizers(L);
1088 1 : return (n * GCFINALIZECOST);
1089 : }
1090 : else { /* emergency mode or no more finalizers */
1091 245 : g->gcstate = GCSpause; /* finish collection */
1092 245 : return 0;
1093 : }
1094 : }
1095 0 : default: lua_assert(0); return 0;
1096 : }
1097 : }
1098 :
1099 :
1100 : /*
1101 : ** advances the garbage collector until it reaches a state allowed
1102 : ** by 'statemask'
1103 : */
1104 8 : void luaC_runtilstate (lua_State *L, int statesmask) {
1105 8 : global_State *g = G(L);
1106 326 : while (!testbit(statesmask, g->gcstate))
1107 318 : singlestep(L);
1108 8 : }
1109 :
1110 :
1111 : /*
1112 : ** get GC debt and convert it from Kb to 'work units' (avoid zero debt
1113 : ** and overflows)
1114 : */
1115 1177 : static l_mem getdebt (global_State *g) {
1116 1177 : l_mem debt = g->GCdebt;
1117 1177 : int stepmul = g->gcstepmul;
1118 1177 : if (debt <= 0) return 0; /* minimal debt */
1119 : else {
1120 1174 : debt = (debt / STEPMULADJ) + 1;
1121 1174 : debt = (debt < MAX_LMEM / stepmul) ? debt * stepmul : MAX_LMEM;
1122 1174 : return debt;
1123 : }
1124 : }
1125 :
1126 : /*
1127 : ** performs a basic GC step when collector is running
1128 : */
1129 1177 : void luaC_step (lua_State *L) {
1130 1177 : global_State *g = G(L);
1131 1177 : l_mem debt = getdebt(g); /* GC deficit (be paid now) */
1132 1177 : if (!g->gcrunning) { /* not running? */
1133 0 : luaE_setdebt(g, -GCSTEPSIZE * 10); /* avoid being called too often */
1134 0 : return;
1135 : }
1136 : do { /* repeat until pause or enough "credit" (negative debt) */
1137 10541 : lu_mem work = singlestep(L); /* perform one single step */
1138 10541 : debt -= work;
1139 10541 : } while (debt > -GCSTEPSIZE && g->gcstate != GCSpause);
1140 1177 : if (g->gcstate == GCSpause)
1141 242 : setpause(g); /* pause until next cycle */
1142 : else {
1143 935 : debt = (debt / g->gcstepmul) * STEPMULADJ; /* convert 'work units' to Kb */
1144 935 : luaE_setdebt(g, debt);
1145 935 : runafewfinalizers(L);
1146 : }
1147 : }
1148 :
1149 :
1150 : /*
1151 : ** Performs a full GC cycle; if 'isemergency', set a flag to avoid
1152 : ** some operations which could change the interpreter state in some
1153 : ** unexpected ways (running finalizers and shrinking some structures).
1154 : ** Before running the collection, check 'keepinvariant'; if it is true,
1155 : ** there may be some objects marked as black, so the collector has
1156 : ** to sweep all objects to turn them back to white (as white has not
1157 : ** changed, nothing will be collected).
1158 : */
1159 2 : void luaC_fullgc (lua_State *L, int isemergency) {
1160 2 : global_State *g = G(L);
1161 : lua_assert(g->gckind == KGC_NORMAL);
1162 2 : if (isemergency) g->gckind = KGC_EMERGENCY; /* set flag */
1163 2 : if (keepinvariant(g)) { /* black objects? */
1164 1 : entersweep(L); /* sweep everything to turn them back to white */
1165 : }
1166 : /* finish any pending sweep phase to start a new cycle */
1167 2 : luaC_runtilstate(L, bitmask(GCSpause));
1168 2 : luaC_runtilstate(L, ~bitmask(GCSpause)); /* start new collection */
1169 2 : luaC_runtilstate(L, bitmask(GCScallfin)); /* run up to finalizers */
1170 : /* estimate must be correct after a full GC cycle */
1171 : lua_assert(g->GCestimate == gettotalbytes(g));
1172 2 : luaC_runtilstate(L, bitmask(GCSpause)); /* finish collection */
1173 2 : g->gckind = KGC_NORMAL;
1174 2 : setpause(g);
1175 2 : }
1176 :
1177 : /* }====================================================== */
1178 :
1179 :
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