The Battle for Wesnoth  1.15.12+dev
lgc.cpp
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1 /*
2 ** $Id: lgc.c $
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 #include <stdio.h>
13 #include <string.h>
14 
15 
16 #include "lua.h"
17 
18 #include "ldebug.h"
19 #include "ldo.h"
20 #include "lfunc.h"
21 #include "lgc.h"
22 #include "lmem.h"
23 #include "lobject.h"
24 #include "lstate.h"
25 #include "lstring.h"
26 #include "ltable.h"
27 #include "ltm.h"
28 
29 
30 /*
31 ** Maximum number of elements to sweep in each single step.
32 ** (Large enough to dissipate fixed overheads but small enough
33 ** to allow small steps for the collector.)
34 */
35 #define GCSWEEPMAX 100
36 
37 /*
38 ** Maximum number of finalizers to call in each single step.
39 */
40 #define GCFINMAX 10
41 
42 
43 /*
44 ** Cost of calling one finalizer.
45 */
46 #define GCFINALIZECOST 50
47 
48 
49 /*
50 ** The equivalent, in bytes, of one unit of "work" (visiting a slot,
51 ** sweeping an object, etc.)
52 */
53 #define WORK2MEM sizeof(TValue)
54 
55 
56 /*
57 ** macro to adjust 'pause': 'pause' is actually used like
58 ** 'pause / PAUSEADJ' (value chosen by tests)
59 */
60 #define PAUSEADJ 100
61 
62 
63 /* mask with all color bits */
64 #define maskcolors (bitmask(BLACKBIT) | WHITEBITS)
65 
66 /* mask with all GC bits */
67 #define maskgcbits (maskcolors | AGEBITS)
68 
69 
70 /* macro to erase all color bits then set only the current white bit */
71 #define makewhite(g,x) \
72  (x->marked = cast_byte((x->marked & ~maskcolors) | luaC_white(g)))
73 
74 /* make an object gray (neither white nor black) */
75 #define set2gray(x) resetbits(x->marked, maskcolors)
76 
77 
78 /* make an object black (coming from any color) */
79 #define set2black(x) \
80  (x->marked = cast_byte((x->marked & ~WHITEBITS) | bitmask(BLACKBIT)))
81 
82 
83 #define valiswhite(x) (iscollectable(x) && iswhite(gcvalue(x)))
84 
85 #define keyiswhite(n) (keyiscollectable(n) && iswhite(gckey(n)))
86 
87 
88 /*
89 ** Protected access to objects in values
90 */
91 #define gcvalueN(o) (iscollectable(o) ? gcvalue(o) : NULL)
92 
93 
94 #define markvalue(g,o) { checkliveness(g->mainthread,o); \
95  if (valiswhite(o)) reallymarkobject(g,gcvalue(o)); }
96 
97 #define markkey(g, n) { if keyiswhite(n) reallymarkobject(g,gckey(n)); }
98 
99 #define markobject(g,t) { if (iswhite(t)) reallymarkobject(g, obj2gco(t)); }
100 
101 /*
102 ** mark an object that can be NULL (either because it is really optional,
103 ** or it was stripped as debug info, or inside an uncompleted structure)
104 */
105 #define markobjectN(g,t) { if (t) markobject(g,t); }
106 
107 static void reallymarkobject (global_State *g, GCObject *o);
108 static lu_mem atomic (lua_State *L);
109 static void entersweep (lua_State *L);
110 
111 
112 /*
113 ** {======================================================
114 ** Generic functions
115 ** =======================================================
116 */
117 
118 
119 /*
120 ** one after last element in a hash array
121 */
122 #define gnodelast(h) gnode(h, cast_sizet(sizenode(h)))
123 
124 
125 static GCObject **getgclist (GCObject *o) {
126  switch (o->tt) {
127  case LUA_VTABLE: return &gco2t(o)->gclist;
128  case LUA_VLCL: return &gco2lcl(o)->gclist;
129  case LUA_VCCL: return &gco2ccl(o)->gclist;
130  case LUA_VTHREAD: return &gco2th(o)->gclist;
131  case LUA_VPROTO: return &gco2p(o)->gclist;
132  case LUA_VUSERDATA: {
133  Udata *u = gco2u(o);
134  lua_assert(u->nuvalue > 0);
135  return &u->gclist;
136  }
137  default: lua_assert(0); return 0;
138  }
139 }
140 
141 
142 /*
143 ** Link a collectable object 'o' with a known type into the list 'p'.
144 ** (Must be a macro to access the 'gclist' field in different types.)
145 */
146 #define linkgclist(o,p) linkgclist_(obj2gco(o), &(o)->gclist, &(p))
147 
148 static void linkgclist_ (GCObject *o, GCObject **pnext, GCObject **list) {
149  lua_assert(!isgray(o)); /* cannot be in a gray list */
150  *pnext = *list;
151  *list = o;
152  set2gray(o); /* now it is */
153 }
154 
155 
156 /*
157 ** Link a generic collectable object 'o' into the list 'p'.
158 */
159 #define linkobjgclist(o,p) linkgclist_(obj2gco(o), getgclist(o), &(p))
160 
161 
162 
163 /*
164 ** Clear keys for empty entries in tables. If entry is empty, mark its
165 ** entry as dead. This allows the collection of the key, but keeps its
166 ** entry in the table: its removal could break a chain and could break
167 ** a table traversal. Other places never manipulate dead keys, because
168 ** its associated empty value is enough to signal that the entry is
169 ** logically empty.
170 */
171 static void clearkey (Node *n) {
172  lua_assert(isempty(gval(n)));
173  if (keyiscollectable(n))
174  setdeadkey(n); /* unused key; remove it */
175 }
176 
177 
178 /*
179 ** tells whether a key or value can be cleared from a weak
180 ** table. Non-collectable objects are never removed from weak
181 ** tables. Strings behave as 'values', so are never removed too. for
182 ** other objects: if really collected, cannot keep them; for objects
183 ** being finalized, keep them in keys, but not in values
184 */
185 static int iscleared (global_State *g, const GCObject *o) {
186  if (o == NULL) return 0; /* non-collectable value */
187  else if (novariant(o->tt) == LUA_TSTRING) {
188  markobject(g, o); /* strings are 'values', so are never weak */
189  return 0;
190  }
191  else return iswhite(o);
192 }
193 
194 
195 /*
196 ** Barrier that moves collector forward, that is, marks the white object
197 ** 'v' being pointed by the black object 'o'. In the generational
198 ** mode, 'v' must also become old, if 'o' is old; however, it cannot
199 ** be changed directly to OLD, because it may still point to non-old
200 ** objects. So, it is marked as OLD0. In the next cycle it will become
201 ** OLD1, and in the next it will finally become OLD (regular old). By
202 ** then, any object it points to will also be old. If called in the
203 ** incremental sweep phase, it clears the black object to white (sweep
204 ** it) to avoid other barrier calls for this same object. (That cannot
205 ** be done is generational mode, as its sweep does not distinguish
206 ** whites from deads.)
207 */
209  global_State *g = G(L);
210  lua_assert(isblack(o) && iswhite(v) && !isdead(g, v) && !isdead(g, o));
211  if (keepinvariant(g)) { /* must keep invariant? */
212  reallymarkobject(g, v); /* restore invariant */
213  if (isold(o)) {
214  lua_assert(!isold(v)); /* white object could not be old */
215  setage(v, G_OLD0); /* restore generational invariant */
216  }
217  }
218  else { /* sweep phase */
220  if (g->gckind == KGC_INC) /* incremental mode? */
221  makewhite(g, o); /* mark 'o' as white to avoid other barriers */
222  }
223 }
224 
225 
226 /*
227 ** barrier that moves collector backward, that is, mark the black object
228 ** pointing to a white object as gray again.
229 */
231  global_State *g = G(L);
232  lua_assert(isblack(o) && !isdead(g, o));
233  lua_assert((g->gckind == KGC_GEN) == (isold(o) && getage(o) != G_TOUCHED1));
234  if (getage(o) == G_TOUCHED2) /* already in gray list? */
235  set2gray(o); /* make it gray to become touched1 */
236  else /* link it in 'grayagain' and paint it gray */
237  linkobjgclist(o, g->grayagain);
238  if (isold(o)) /* generational mode? */
239  setage(o, G_TOUCHED1); /* touched in current cycle */
240 }
241 
242 
243 void luaC_fix (lua_State *L, GCObject *o) {
244  global_State *g = G(L);
245  lua_assert(g->allgc == o); /* object must be 1st in 'allgc' list! */
246  set2gray(o); /* they will be gray forever */
247  setage(o, G_OLD); /* and old forever */
248  g->allgc = o->next; /* remove object from 'allgc' list */
249  o->next = g->fixedgc; /* link it to 'fixedgc' list */
250  g->fixedgc = o;
251 }
252 
253 
254 /*
255 ** create a new collectable object (with given type and size) and link
256 ** it to 'allgc' list.
257 */
258 GCObject *luaC_newobj (lua_State *L, int tt, size_t sz) {
259  global_State *g = G(L);
260  GCObject *o = cast(GCObject *, luaM_newobject(L, novariant(tt), sz));
261  o->marked = luaC_white(g);
262  o->tt = tt;
263  o->next = g->allgc;
264  g->allgc = o;
265  return o;
266 }
267 
268 /* }====================================================== */
269 
270 
271 
272 /*
273 ** {======================================================
274 ** Mark functions
275 ** =======================================================
276 */
277 
278 
279 /*
280 ** Mark an object. Userdata with no user values, strings, and closed
281 ** upvalues are visited and turned black here. Open upvalues are
282 ** already indirectly linked through their respective threads in the
283 ** 'twups' list, so they don't go to the gray list; nevertheless, they
284 ** are kept gray to avoid barriers, as their values will be revisited
285 ** by the thread or by 'remarkupvals'. Other objects are added to the
286 ** gray list to be visited (and turned black) later. Both userdata and
287 ** upvalues can call this function recursively, but this recursion goes
288 ** for at most two levels: An upvalue cannot refer to another upvalue
289 ** (only closures can), and a userdata's metatable must be a table.
290 */
292  switch (o->tt) {
293  case LUA_VSHRSTR:
294  case LUA_VLNGSTR: {
295  set2black(o); /* nothing to visit */
296  break;
297  }
298  case LUA_VUPVAL: {
299  UpVal *uv = gco2upv(o);
300  if (upisopen(uv))
301  set2gray(uv); /* open upvalues are kept gray */
302  else
303  set2black(uv); /* closed upvalues are visited here */
304  markvalue(g, uv->v); /* mark its content */
305  break;
306  }
307  case LUA_VUSERDATA: {
308  Udata *u = gco2u(o);
309  if (u->nuvalue == 0) { /* no user values? */
310  markobjectN(g, u->metatable); /* mark its metatable */
311  set2black(u); /* nothing else to mark */
312  break;
313  }
314  /* else... */
315  } /* FALLTHROUGH */
316  case LUA_VLCL: case LUA_VCCL: case LUA_VTABLE:
317  case LUA_VTHREAD: case LUA_VPROTO: {
318  linkobjgclist(o, g->gray); /* to be visited later */
319  break;
320  }
321  default: lua_assert(0); break;
322  }
323 }
324 
325 
326 /*
327 ** mark metamethods for basic types
328 */
329 static void markmt (global_State *g) {
330  int i;
331  for (i=0; i < LUA_NUMTAGS; i++)
332  markobjectN(g, g->mt[i]);
333 }
334 
335 
336 /*
337 ** mark all objects in list of being-finalized
338 */
340  GCObject *o;
341  lu_mem count = 0;
342  for (o = g->tobefnz; o != NULL; o = o->next) {
343  count++;
344  markobject(g, o);
345  }
346  return count;
347 }
348 
349 
350 /*
351 ** For each non-marked thread, simulates a barrier between each open
352 ** upvalue and its value. (If the thread is collected, the value will be
353 ** assigned to the upvalue, but then it can be too late for the barrier
354 ** to act. The "barrier" does not need to check colors: A non-marked
355 ** thread must be young; upvalues cannot be older than their threads; so
356 ** any visited upvalue must be young too.) Also removes the thread from
357 ** the list, as it was already visited. Removes also threads with no
358 ** upvalues, as they have nothing to be checked. (If the thread gets an
359 ** upvalue later, it will be linked in the list again.)
360 */
361 static int remarkupvals (global_State *g) {
362  lua_State *thread;
363  lua_State **p = &g->twups;
364  int work = 0; /* estimate of how much work was done here */
365  while ((thread = *p) != NULL) {
366  work++;
367  if (!iswhite(thread) && thread->openupval != NULL)
368  p = &thread->twups; /* keep marked thread with upvalues in the list */
369  else { /* thread is not marked or without upvalues */
370  UpVal *uv;
371  lua_assert(!isold(thread) || thread->openupval == NULL);
372  *p = thread->twups; /* remove thread from the list */
373  thread->twups = thread; /* mark that it is out of list */
374  for (uv = thread->openupval; uv != NULL; uv = uv->u.open.next) {
375  lua_assert(getage(uv) <= getage(thread));
376  work++;
377  if (!iswhite(uv)) { /* upvalue already visited? */
378  lua_assert(upisopen(uv) && isgray(uv));
379  markvalue(g, uv->v); /* mark its value */
380  }
381  }
382  }
383  }
384  return work;
385 }
386 
387 
388 static void cleargraylists (global_State *g) {
389  g->gray = g->grayagain = NULL;
390  g->weak = g->allweak = g->ephemeron = NULL;
391 }
392 
393 
394 /*
395 ** mark root set and reset all gray lists, to start a new collection
396 */
398  cleargraylists(g);
399  markobject(g, g->mainthread);
400  markvalue(g, &g->l_registry);
401  markmt(g);
402  markbeingfnz(g); /* mark any finalizing object left from previous cycle */
403 }
404 
405 /* }====================================================== */
406 
407 
408 /*
409 ** {======================================================
410 ** Traverse functions
411 ** =======================================================
412 */
413 
414 
415 /*
416 ** Check whether object 'o' should be kept in the 'grayagain' list for
417 ** post-processing by 'correctgraylist'. (It could put all old objects
418 ** in the list and leave all the work to 'correctgraylist', but it is
419 ** more efficient to avoid adding elements that will be removed.) Only
420 ** TOUCHED1 objects need to be in the list. TOUCHED2 doesn't need to go
421 ** back to a gray list, but then it must become OLD. (That is what
422 ** 'correctgraylist' does when it finds a TOUCHED2 object.)
423 */
424 static void genlink (global_State *g, GCObject *o) {
425  lua_assert(isblack(o));
426  if (getage(o) == G_TOUCHED1) { /* touched in this cycle? */
427  linkobjgclist(o, g->grayagain); /* link it back in 'grayagain' */
428  } /* everything else do not need to be linked back */
429  else if (getage(o) == G_TOUCHED2)
430  changeage(o, G_TOUCHED2, G_OLD); /* advance age */
431 }
432 
433 
434 /*
435 ** Traverse a table with weak values and link it to proper list. During
436 ** propagate phase, keep it in 'grayagain' list, to be revisited in the
437 ** atomic phase. In the atomic phase, if table has any white value,
438 ** put it in 'weak' list, to be cleared.
439 */
441  Node *n, *limit = gnodelast(h);
442  /* if there is array part, assume it may have white values (it is not
443  worth traversing it now just to check) */
444  int hasclears = (h->alimit > 0);
445  for (n = gnode(h, 0); n < limit; n++) { /* traverse hash part */
446  if (isempty(gval(n))) /* entry is empty? */
447  clearkey(n); /* clear its key */
448  else {
449  lua_assert(!keyisnil(n));
450  markkey(g, n);
451  if (!hasclears && iscleared(g, gcvalueN(gval(n)))) /* a white value? */
452  hasclears = 1; /* table will have to be cleared */
453  }
454  }
455  if (g->gcstate == GCSatomic && hasclears)
456  linkgclist(h, g->weak); /* has to be cleared later */
457  else
458  linkgclist(h, g->grayagain); /* must retraverse it in atomic phase */
459 }
460 
461 
462 /*
463 ** Traverse an ephemeron table and link it to proper list. Returns true
464 ** iff any object was marked during this traversal (which implies that
465 ** convergence has to continue). During propagation phase, keep table
466 ** in 'grayagain' list, to be visited again in the atomic phase. In
467 ** the atomic phase, if table has any white->white entry, it has to
468 ** be revisited during ephemeron convergence (as that key may turn
469 ** black). Otherwise, if it has any white key, table has to be cleared
470 ** (in the atomic phase). In generational mode, some tables
471 ** must be kept in some gray list for post-processing; this is done
472 ** by 'genlink'.
473 */
474 static int traverseephemeron (global_State *g, Table *h, int inv) {
475  int marked = 0; /* true if an object is marked in this traversal */
476  int hasclears = 0; /* true if table has white keys */
477  int hasww = 0; /* true if table has entry "white-key -> white-value" */
478  unsigned int i;
479  unsigned int asize = luaH_realasize(h);
480  unsigned int nsize = sizenode(h);
481  /* traverse array part */
482  for (i = 0; i < asize; i++) {
483  if (valiswhite(&h->array[i])) {
484  marked = 1;
485  reallymarkobject(g, gcvalue(&h->array[i]));
486  }
487  }
488  /* traverse hash part; if 'inv', traverse descending
489  (see 'convergeephemerons') */
490  for (i = 0; i < nsize; i++) {
491  Node *n = inv ? gnode(h, nsize - 1 - i) : gnode(h, i);
492  if (isempty(gval(n))) /* entry is empty? */
493  clearkey(n); /* clear its key */
494  else if (iscleared(g, gckeyN(n))) { /* key is not marked (yet)? */
495  hasclears = 1; /* table must be cleared */
496  if (valiswhite(gval(n))) /* value not marked yet? */
497  hasww = 1; /* white-white entry */
498  }
499  else if (valiswhite(gval(n))) { /* value not marked yet? */
500  marked = 1;
501  reallymarkobject(g, gcvalue(gval(n))); /* mark it now */
502  }
503  }
504  /* link table into proper list */
505  if (g->gcstate == GCSpropagate)
506  linkgclist(h, g->grayagain); /* must retraverse it in atomic phase */
507  else if (hasww) /* table has white->white entries? */
508  linkgclist(h, g->ephemeron); /* have to propagate again */
509  else if (hasclears) /* table has white keys? */
510  linkgclist(h, g->allweak); /* may have to clean white keys */
511  else
512  genlink(g, obj2gco(h)); /* check whether collector still needs to see it */
513  return marked;
514 }
515 
516 
518  Node *n, *limit = gnodelast(h);
519  unsigned int i;
520  unsigned int asize = luaH_realasize(h);
521  for (i = 0; i < asize; i++) /* traverse array part */
522  markvalue(g, &h->array[i]);
523  for (n = gnode(h, 0); n < limit; n++) { /* traverse hash part */
524  if (isempty(gval(n))) /* entry is empty? */
525  clearkey(n); /* clear its key */
526  else {
527  lua_assert(!keyisnil(n));
528  markkey(g, n);
529  markvalue(g, gval(n));
530  }
531  }
532  genlink(g, obj2gco(h));
533 }
534 
535 
537  const char *weakkey, *weakvalue;
538  const TValue *mode = gfasttm(g, h->metatable, TM_MODE);
539  markobjectN(g, h->metatable);
540  if (mode && ttisstring(mode) && /* is there a weak mode? */
541  (cast_void(weakkey = strchr(svalue(mode), 'k')),
542  cast_void(weakvalue = strchr(svalue(mode), 'v')),
543  (weakkey || weakvalue))) { /* is really weak? */
544  if (!weakkey) /* strong keys? */
545  traverseweakvalue(g, h);
546  else if (!weakvalue) /* strong values? */
547  traverseephemeron(g, h, 0);
548  else /* all weak */
549  linkgclist(h, g->allweak); /* nothing to traverse now */
550  }
551  else /* not weak */
552  traversestrongtable(g, h);
553  return 1 + h->alimit + 2 * allocsizenode(h);
554 }
555 
556 
557 static int traverseudata (global_State *g, Udata *u) {
558  int i;
559  markobjectN(g, u->metatable); /* mark its metatable */
560  for (i = 0; i < u->nuvalue; i++)
561  markvalue(g, &u->uv[i].uv);
562  genlink(g, obj2gco(u));
563  return 1 + u->nuvalue;
564 }
565 
566 
567 /*
568 ** Traverse a prototype. (While a prototype is being build, its
569 ** arrays can be larger than needed; the extra slots are filled with
570 ** NULL, so the use of 'markobjectN')
571 */
572 static int traverseproto (global_State *g, Proto *f) {
573  int i;
574  markobjectN(g, f->source);
575  for (i = 0; i < f->sizek; i++) /* mark literals */
576  markvalue(g, &f->k[i]);
577  for (i = 0; i < f->sizeupvalues; i++) /* mark upvalue names */
578  markobjectN(g, f->upvalues[i].name);
579  for (i = 0; i < f->sizep; i++) /* mark nested protos */
580  markobjectN(g, f->p[i]);
581  for (i = 0; i < f->sizelocvars; i++) /* mark local-variable names */
582  markobjectN(g, f->locvars[i].varname);
583  return 1 + f->sizek + f->sizeupvalues + f->sizep + f->sizelocvars;
584 }
585 
586 
588  int i;
589  for (i = 0; i < cl->nupvalues; i++) /* mark its upvalues */
590  markvalue(g, &cl->upvalue[i]);
591  return 1 + cl->nupvalues;
592 }
593 
594 /*
595 ** Traverse a Lua closure, marking its prototype and its upvalues.
596 ** (Both can be NULL while closure is being created.)
597 */
599  int i;
600  markobjectN(g, cl->p); /* mark its prototype */
601  for (i = 0; i < cl->nupvalues; i++) { /* visit its upvalues */
602  UpVal *uv = cl->upvals[i];
603  markobjectN(g, uv); /* mark upvalue */
604  }
605  return 1 + cl->nupvalues;
606 }
607 
608 
609 /*
610 ** Traverse a thread, marking the elements in the stack up to its top
611 ** and cleaning the rest of the stack in the final traversal. That
612 ** ensures that the entire stack have valid (non-dead) objects.
613 ** Threads have no barriers. In gen. mode, old threads must be visited
614 ** at every cycle, because they might point to young objects. In inc.
615 ** mode, the thread can still be modified before the end of the cycle,
616 ** and therefore it must be visited again in the atomic phase. To ensure
617 ** these visits, threads must return to a gray list if they are not new
618 ** (which can only happen in generational mode) or if the traverse is in
619 ** the propagate phase (which can only happen in incremental mode).
620 */
622  UpVal *uv;
623  StkId o = th->stack;
624  if (isold(th) || g->gcstate == GCSpropagate)
625  linkgclist(th, g->grayagain); /* insert into 'grayagain' list */
626  if (o == NULL)
627  return 1; /* stack not completely built yet */
628  lua_assert(g->gcstate == GCSatomic ||
629  th->openupval == NULL || isintwups(th));
630  for (; o < th->top; o++) /* mark live elements in the stack */
631  markvalue(g, s2v(o));
632  for (uv = th->openupval; uv != NULL; uv = uv->u.open.next)
633  markobject(g, uv); /* open upvalues cannot be collected */
634  if (g->gcstate == GCSatomic) { /* final traversal? */
635  for (; o < th->stack_last + EXTRA_STACK; o++)
636  setnilvalue(s2v(o)); /* clear dead stack slice */
637  /* 'remarkupvals' may have removed thread from 'twups' list */
638  if (!isintwups(th) && th->openupval != NULL) {
639  th->twups = g->twups; /* link it back to the list */
640  g->twups = th;
641  }
642  }
643  else if (!g->gcemergency)
644  luaD_shrinkstack(th); /* do not change stack in emergency cycle */
645  return 1 + stacksize(th);
646 }
647 
648 
649 /*
650 ** traverse one gray object, turning it to black.
651 */
653  GCObject *o = g->gray;
654  nw2black(o);
655  g->gray = *getgclist(o); /* remove from 'gray' list */
656  switch (o->tt) {
657  case LUA_VTABLE: return traversetable(g, gco2t(o));
658  case LUA_VUSERDATA: return traverseudata(g, gco2u(o));
659  case LUA_VLCL: return traverseLclosure(g, gco2lcl(o));
660  case LUA_VCCL: return traverseCclosure(g, gco2ccl(o));
661  case LUA_VPROTO: return traverseproto(g, gco2p(o));
662  case LUA_VTHREAD: return traversethread(g, gco2th(o));
663  default: lua_assert(0); return 0;
664  }
665 }
666 
667 
669  lu_mem tot = 0;
670  while (g->gray)
671  tot += propagatemark(g);
672  return tot;
673 }
674 
675 
676 /*
677 ** Traverse all ephemeron tables propagating marks from keys to values.
678 ** Repeat until it converges, that is, nothing new is marked. 'dir'
679 ** inverts the direction of the traversals, trying to speed up
680 ** convergence on chains in the same table.
681 **
682 */
684  int changed;
685  int dir = 0;
686  do {
687  GCObject *w;
688  GCObject *next = g->ephemeron; /* get ephemeron list */
689  g->ephemeron = NULL; /* tables may return to this list when traversed */
690  changed = 0;
691  while ((w = next) != NULL) { /* for each ephemeron table */
692  Table *h = gco2t(w);
693  next = h->gclist; /* list is rebuilt during loop */
694  nw2black(h); /* out of the list (for now) */
695  if (traverseephemeron(g, h, dir)) { /* marked some value? */
696  propagateall(g); /* propagate changes */
697  changed = 1; /* will have to revisit all ephemeron tables */
698  }
699  }
700  dir = !dir; /* invert direction next time */
701  } while (changed); /* repeat until no more changes */
702 }
703 
704 /* }====================================================== */
705 
706 
707 /*
708 ** {======================================================
709 ** Sweep Functions
710 ** =======================================================
711 */
712 
713 
714 /*
715 ** clear entries with unmarked keys from all weaktables in list 'l'
716 */
717 static void clearbykeys (global_State *g, GCObject *l) {
718  for (; l; l = gco2t(l)->gclist) {
719  Table *h = gco2t(l);
720  Node *limit = gnodelast(h);
721  Node *n;
722  for (n = gnode(h, 0); n < limit; n++) {
723  if (iscleared(g, gckeyN(n))) /* unmarked key? */
724  setempty(gval(n)); /* remove entry */
725  if (isempty(gval(n))) /* is entry empty? */
726  clearkey(n); /* clear its key */
727  }
728  }
729 }
730 
731 
732 /*
733 ** clear entries with unmarked values from all weaktables in list 'l' up
734 ** to element 'f'
735 */
737  for (; l != f; l = gco2t(l)->gclist) {
738  Table *h = gco2t(l);
739  Node *n, *limit = gnodelast(h);
740  unsigned int i;
741  unsigned int asize = luaH_realasize(h);
742  for (i = 0; i < asize; i++) {
743  TValue *o = &h->array[i];
744  if (iscleared(g, gcvalueN(o))) /* value was collected? */
745  setempty(o); /* remove entry */
746  }
747  for (n = gnode(h, 0); n < limit; n++) {
748  if (iscleared(g, gcvalueN(gval(n)))) /* unmarked value? */
749  setempty(gval(n)); /* remove entry */
750  if (isempty(gval(n))) /* is entry empty? */
751  clearkey(n); /* clear its key */
752  }
753  }
754 }
755 
756 
757 static void freeupval (lua_State *L, UpVal *uv) {
758  if (upisopen(uv))
759  luaF_unlinkupval(uv);
760  luaM_free(L, uv);
761 }
762 
763 
764 static void freeobj (lua_State *L, GCObject *o) {
765  switch (o->tt) {
766  case LUA_VPROTO:
767  luaF_freeproto(L, gco2p(o));
768  break;
769  case LUA_VUPVAL:
770  freeupval(L, gco2upv(o));
771  break;
772  case LUA_VLCL: {
773  LClosure *cl = gco2lcl(o);
774  luaM_freemem(L, cl, sizeLclosure(cl->nupvalues));
775  break;
776  }
777  case LUA_VCCL: {
778  CClosure *cl = gco2ccl(o);
779  luaM_freemem(L, cl, sizeCclosure(cl->nupvalues));
780  break;
781  }
782  case LUA_VTABLE:
783  luaH_free(L, gco2t(o));
784  break;
785  case LUA_VTHREAD:
786  luaE_freethread(L, gco2th(o));
787  break;
788  case LUA_VUSERDATA: {
789  Udata *u = gco2u(o);
790  luaM_freemem(L, o, sizeudata(u->nuvalue, u->len));
791  break;
792  }
793  case LUA_VSHRSTR: {
794  TString *ts = gco2ts(o);
795  luaS_remove(L, ts); /* remove it from hash table */
796  luaM_freemem(L, ts, sizelstring(ts->shrlen));
797  break;
798  }
799  case LUA_VLNGSTR: {
800  TString *ts = gco2ts(o);
801  luaM_freemem(L, ts, sizelstring(ts->u.lnglen));
802  break;
803  }
804  default: lua_assert(0);
805  }
806 }
807 
808 
809 /*
810 ** sweep at most 'countin' elements from a list of GCObjects erasing dead
811 ** objects, where a dead object is one marked with the old (non current)
812 ** white; change all non-dead objects back to white, preparing for next
813 ** collection cycle. Return where to continue the traversal or NULL if
814 ** list is finished. ('*countout' gets the number of elements traversed.)
815 */
816 static GCObject **sweeplist (lua_State *L, GCObject **p, int countin,
817  int *countout) {
818  global_State *g = G(L);
819  int ow = otherwhite(g);
820  int i;
821  int white = luaC_white(g); /* current white */
822  for (i = 0; *p != NULL && i < countin; i++) {
823  GCObject *curr = *p;
824  int marked = curr->marked;
825  if (isdeadm(ow, marked)) { /* is 'curr' dead? */
826  *p = curr->next; /* remove 'curr' from list */
827  freeobj(L, curr); /* erase 'curr' */
828  }
829  else { /* change mark to 'white' */
830  curr->marked = cast_byte((marked & ~maskgcbits) | white);
831  p = &curr->next; /* go to next element */
832  }
833  }
834  if (countout)
835  *countout = i; /* number of elements traversed */
836  return (*p == NULL) ? NULL : p;
837 }
838 
839 
840 /*
841 ** sweep a list until a live object (or end of list)
842 */
844  GCObject **old = p;
845  do {
846  p = sweeplist(L, p, 1, NULL);
847  } while (p == old);
848  return p;
849 }
850 
851 /* }====================================================== */
852 
853 
854 /*
855 ** {======================================================
856 ** Finalization
857 ** =======================================================
858 */
859 
860 /*
861 ** If possible, shrink string table.
862 */
863 static void checkSizes (lua_State *L, global_State *g) {
864  if (!g->gcemergency) {
865  if (g->strt.nuse < g->strt.size / 4) { /* string table too big? */
866  l_mem olddebt = g->GCdebt;
867  luaS_resize(L, g->strt.size / 2);
868  g->GCestimate += g->GCdebt - olddebt; /* correct estimate */
869  }
870  }
871 }
872 
873 
874 /*
875 ** Get the next udata to be finalized from the 'tobefnz' list, and
876 ** link it back into the 'allgc' list.
877 */
879  GCObject *o = g->tobefnz; /* get first element */
881  g->tobefnz = o->next; /* remove it from 'tobefnz' list */
882  o->next = g->allgc; /* return it to 'allgc' list */
883  g->allgc = o;
884  resetbit(o->marked, FINALIZEDBIT); /* object is "normal" again */
885  if (issweepphase(g))
886  makewhite(g, o); /* "sweep" object */
887  else if (getage(o) == G_OLD1)
888  g->firstold1 = o; /* it is the first OLD1 object in the list */
889  return o;
890 }
891 
892 
893 static void dothecall (lua_State *L, void *ud) {
894  UNUSED(ud);
895  luaD_callnoyield(L, L->top - 2, 0);
896 }
897 
898 
899 static void GCTM (lua_State *L) {
900  global_State *g = G(L);
901  const TValue *tm;
902  TValue v;
903  lua_assert(!g->gcemergency);
904  setgcovalue(L, &v, udata2finalize(g));
905  tm = luaT_gettmbyobj(L, &v, TM_GC);
906  if (!notm(tm)) { /* is there a finalizer? */
907  int status;
908  lu_byte oldah = L->allowhook;
909  int running = g->gcrunning;
910  L->allowhook = 0; /* stop debug hooks during GC metamethod */
911  g->gcrunning = 0; /* avoid GC steps */
912  setobj2s(L, L->top++, tm); /* push finalizer... */
913  setobj2s(L, L->top++, &v); /* ... and its argument */
914  L->ci->callstatus |= CIST_FIN; /* will run a finalizer */
915  status = luaD_pcall(L, dothecall, NULL, savestack(L, L->top - 2), 0);
916  L->ci->callstatus &= ~CIST_FIN; /* not running a finalizer anymore */
917  L->allowhook = oldah; /* restore hooks */
918  g->gcrunning = running; /* restore state */
919  if (unlikely(status != LUA_OK)) { /* error while running __gc? */
920  luaE_warnerror(L, "__gc metamethod");
921  L->top--; /* pops error object */
922  }
923  }
924 }
925 
926 
927 /*
928 ** Call a few finalizers
929 */
930 static int runafewfinalizers (lua_State *L, int n) {
931  global_State *g = G(L);
932  int i;
933  for (i = 0; i < n && g->tobefnz; i++)
934  GCTM(L); /* call one finalizer */
935  return i;
936 }
937 
938 
939 /*
940 ** call all pending finalizers
941 */
943  global_State *g = G(L);
944  while (g->tobefnz)
945  GCTM(L);
946 }
947 
948 
949 /*
950 ** find last 'next' field in list 'p' list (to add elements in its end)
951 */
952 static GCObject **findlast (GCObject **p) {
953  while (*p != NULL)
954  p = &(*p)->next;
955  return p;
956 }
957 
958 
959 /*
960 ** Move all unreachable objects (or 'all' objects) that need
961 ** finalization from list 'finobj' to list 'tobefnz' (to be finalized).
962 ** (Note that objects after 'finobjold1' cannot be white, so they
963 ** don't need to be traversed. In incremental mode, 'finobjold1' is NULL,
964 ** so the whole list is traversed.)
965 */
966 static void separatetobefnz (global_State *g, int all) {
967  GCObject *curr;
968  GCObject **p = &g->finobj;
969  GCObject **lastnext = findlast(&g->tobefnz);
970  while ((curr = *p) != g->finobjold1) { /* traverse all finalizable objects */
971  lua_assert(tofinalize(curr));
972  if (!(iswhite(curr) || all)) /* not being collected? */
973  p = &curr->next; /* don't bother with it */
974  else {
975  if (curr == g->finobjsur) /* removing 'finobjsur'? */
976  g->finobjsur = curr->next; /* correct it */
977  *p = curr->next; /* remove 'curr' from 'finobj' list */
978  curr->next = *lastnext; /* link at the end of 'tobefnz' list */
979  *lastnext = curr;
980  lastnext = &curr->next;
981  }
982  }
983 }
984 
985 
986 /*
987 ** If pointer 'p' points to 'o', move it to the next element.
988 */
989 static void checkpointer (GCObject **p, GCObject *o) {
990  if (o == *p)
991  *p = o->next;
992 }
993 
994 
995 /*
996 ** Correct pointers to objects inside 'allgc' list when
997 ** object 'o' is being removed from the list.
998 */
1000  checkpointer(&g->survival, o);
1001  checkpointer(&g->old1, o);
1002  checkpointer(&g->reallyold, o);
1003  checkpointer(&g->firstold1, o);
1004 }
1005 
1006 
1007 /*
1008 ** if object 'o' has a finalizer, remove it from 'allgc' list (must
1009 ** search the list to find it) and link it in 'finobj' list.
1010 */
1012  global_State *g = G(L);
1013  if (tofinalize(o) || /* obj. is already marked... */
1014  gfasttm(g, mt, TM_GC) == NULL) /* or has no finalizer? */
1015  return; /* nothing to be done */
1016  else { /* move 'o' to 'finobj' list */
1017  GCObject **p;
1018  if (issweepphase(g)) {
1019  makewhite(g, o); /* "sweep" object 'o' */
1020  if (g->sweepgc == &o->next) /* should not remove 'sweepgc' object */
1021  g->sweepgc = sweeptolive(L, g->sweepgc); /* change 'sweepgc' */
1022  }
1023  else
1024  correctpointers(g, o);
1025  /* search for pointer pointing to 'o' */
1026  for (p = &g->allgc; *p != o; p = &(*p)->next) { /* empty */ }
1027  *p = o->next; /* remove 'o' from 'allgc' list */
1028  o->next = g->finobj; /* link it in 'finobj' list */
1029  g->finobj = o;
1030  l_setbit(o->marked, FINALIZEDBIT); /* mark it as such */
1031  }
1032 }
1033 
1034 /* }====================================================== */
1035 
1036 
1037 /*
1038 ** {======================================================
1039 ** Generational Collector
1040 ** =======================================================
1041 */
1042 
1043 static void setpause (global_State *g);
1044 
1045 
1046 /*
1047 ** Sweep a list of objects to enter generational mode. Deletes dead
1048 ** objects and turns the non dead to old. All non-dead threads---which
1049 ** are now old---must be in a gray list. Everything else is not in a
1050 ** gray list. Open upvalues are also kept gray.
1051 */
1052 static void sweep2old (lua_State *L, GCObject **p) {
1053  GCObject *curr;
1054  global_State *g = G(L);
1055  while ((curr = *p) != NULL) {
1056  if (iswhite(curr)) { /* is 'curr' dead? */
1057  lua_assert(isdead(g, curr));
1058  *p = curr->next; /* remove 'curr' from list */
1059  freeobj(L, curr); /* erase 'curr' */
1060  }
1061  else { /* all surviving objects become old */
1062  setage(curr, G_OLD);
1063  if (curr->tt == LUA_VTHREAD) { /* threads must be watched */
1064  lua_State *th = gco2th(curr);
1065  linkgclist(th, g->grayagain); /* insert into 'grayagain' list */
1066  }
1067  else if (curr->tt == LUA_VUPVAL && upisopen(gco2upv(curr)))
1068  set2gray(curr); /* open upvalues are always gray */
1069  else /* everything else is black */
1070  nw2black(curr);
1071  p = &curr->next; /* go to next element */
1072  }
1073  }
1074 }
1075 
1076 
1077 /*
1078 ** Sweep for generational mode. Delete dead objects. (Because the
1079 ** collection is not incremental, there are no "new white" objects
1080 ** during the sweep. So, any white object must be dead.) For
1081 ** non-dead objects, advance their ages and clear the color of
1082 ** new objects. (Old objects keep their colors.)
1083 ** The ages of G_TOUCHED1 and G_TOUCHED2 objects cannot be advanced
1084 ** here, because these old-generation objects are usually not swept
1085 ** here. They will all be advanced in 'correctgraylist'. That function
1086 ** will also remove objects turned white here from any gray list.
1087 */
1089  GCObject *limit, GCObject **pfirstold1) {
1090  static const lu_byte nextage[] = {
1091  G_SURVIVAL, /* from G_NEW */
1092  G_OLD1, /* from G_SURVIVAL */
1093  G_OLD1, /* from G_OLD0 */
1094  G_OLD, /* from G_OLD1 */
1095  G_OLD, /* from G_OLD (do not change) */
1096  G_TOUCHED1, /* from G_TOUCHED1 (do not change) */
1097  G_TOUCHED2 /* from G_TOUCHED2 (do not change) */
1098  };
1099  int white = luaC_white(g);
1100  GCObject *curr;
1101  while ((curr = *p) != limit) {
1102  if (iswhite(curr)) { /* is 'curr' dead? */
1103  lua_assert(!isold(curr) && isdead(g, curr));
1104  *p = curr->next; /* remove 'curr' from list */
1105  freeobj(L, curr); /* erase 'curr' */
1106  }
1107  else { /* correct mark and age */
1108  if (getage(curr) == G_NEW) { /* new objects go back to white */
1109  int marked = curr->marked & ~maskgcbits; /* erase GC bits */
1110  curr->marked = cast_byte(marked | G_SURVIVAL | white);
1111  }
1112  else { /* all other objects will be old, and so keep their color */
1113  setage(curr, nextage[getage(curr)]);
1114  if (getage(curr) == G_OLD1 && *pfirstold1 == NULL)
1115  *pfirstold1 = curr; /* first OLD1 object in the list */
1116  }
1117  p = &curr->next; /* go to next element */
1118  }
1119  }
1120  return p;
1121 }
1122 
1123 
1124 /*
1125 ** Traverse a list making all its elements white and clearing their
1126 ** age. In incremental mode, all objects are 'new' all the time,
1127 ** except for fixed strings (which are always old).
1128 */
1129 static void whitelist (global_State *g, GCObject *p) {
1130  int white = luaC_white(g);
1131  for (; p != NULL; p = p->next)
1132  p->marked = cast_byte((p->marked & ~maskgcbits) | white);
1133 }
1134 
1135 
1136 /*
1137 ** Correct a list of gray objects. Return pointer to where rest of the
1138 ** list should be linked.
1139 ** Because this correction is done after sweeping, young objects might
1140 ** be turned white and still be in the list. They are only removed.
1141 ** 'TOUCHED1' objects are advanced to 'TOUCHED2' and remain on the list;
1142 ** Non-white threads also remain on the list; 'TOUCHED2' objects become
1143 ** regular old; they and anything else are removed from the list.
1144 */
1146  GCObject *curr;
1147  while ((curr = *p) != NULL) {
1148  GCObject **next = getgclist(curr);
1149  if (iswhite(curr))
1150  goto remove; /* remove all white objects */
1151  else if (getage(curr) == G_TOUCHED1) { /* touched in this cycle? */
1152  lua_assert(isgray(curr));
1153  nw2black(curr); /* make it black, for next barrier */
1155  goto remain; /* keep it in the list and go to next element */
1156  }
1157  else if (curr->tt == LUA_VTHREAD) {
1158  lua_assert(isgray(curr));
1159  goto remain; /* keep non-white threads on the list */
1160  }
1161  else { /* everything else is removed */
1162  lua_assert(isold(curr)); /* young objects should be white here */
1163  if (getage(curr) == G_TOUCHED2) /* advance from TOUCHED2... */
1164  changeage(curr, G_TOUCHED2, G_OLD); /* ... to OLD */
1165  nw2black(curr); /* make object black (to be removed) */
1166  goto remove;
1167  }
1168  remove: *p = *next; continue;
1169  remain: p = next; continue;
1170  }
1171  return p;
1172 }
1173 
1174 
1175 /*
1176 ** Correct all gray lists, coalescing them into 'grayagain'.
1177 */
1178 static void correctgraylists (global_State *g) {
1179  GCObject **list = correctgraylist(&g->grayagain);
1180  *list = g->weak; g->weak = NULL;
1181  list = correctgraylist(list);
1182  *list = g->allweak; g->allweak = NULL;
1183  list = correctgraylist(list);
1184  *list = g->ephemeron; g->ephemeron = NULL;
1185  correctgraylist(list);
1186 }
1187 
1188 
1189 /*
1190 ** Mark black 'OLD1' objects when starting a new young collection.
1191 ** Gray objects are already in some gray list, and so will be visited
1192 ** in the atomic step.
1193 */
1194 static void markold (global_State *g, GCObject *from, GCObject *to) {
1195  GCObject *p;
1196  for (p = from; p != to; p = p->next) {
1197  if (getage(p) == G_OLD1) {
1198  lua_assert(!iswhite(p));
1199  changeage(p, G_OLD1, G_OLD); /* now they are old */
1200  if (isblack(p))
1201  reallymarkobject(g, p);
1202  }
1203  }
1204 }
1205 
1206 
1207 /*
1208 ** Finish a young-generation collection.
1209 */
1210 static void finishgencycle (lua_State *L, global_State *g) {
1211  correctgraylists(g);
1212  checkSizes(L, g);
1213  g->gcstate = GCSpropagate; /* skip restart */
1214  if (!g->gcemergency)
1216 }
1217 
1218 
1219 /*
1220 ** Does a young collection. First, mark 'OLD1' objects. Then does the
1221 ** atomic step. Then, sweep all lists and advance pointers. Finally,
1222 ** finish the collection.
1223 */
1225  GCObject **psurvival; /* to point to first non-dead survival object */
1226  GCObject *dummy; /* dummy out parameter to 'sweepgen' */
1228  if (g->firstold1) { /* are there regular OLD1 objects? */
1229  markold(g, g->firstold1, g->reallyold); /* mark them */
1230  g->firstold1 = NULL; /* no more OLD1 objects (for now) */
1231  }
1232  markold(g, g->finobj, g->finobjrold);
1233  markold(g, g->tobefnz, NULL);
1234  atomic(L);
1235 
1236  /* sweep nursery and get a pointer to its last live element */
1237  g->gcstate = GCSswpallgc;
1238  psurvival = sweepgen(L, g, &g->allgc, g->survival, &g->firstold1);
1239  /* sweep 'survival' */
1240  sweepgen(L, g, psurvival, g->old1, &g->firstold1);
1241  g->reallyold = g->old1;
1242  g->old1 = *psurvival; /* 'survival' survivals are old now */
1243  g->survival = g->allgc; /* all news are survivals */
1244 
1245  /* repeat for 'finobj' lists */
1246  dummy = NULL; /* no 'firstold1' optimization for 'finobj' lists */
1247  psurvival = sweepgen(L, g, &g->finobj, g->finobjsur, &dummy);
1248  /* sweep 'survival' */
1249  sweepgen(L, g, psurvival, g->finobjold1, &dummy);
1250  g->finobjrold = g->finobjold1;
1251  g->finobjold1 = *psurvival; /* 'survival' survivals are old now */
1252  g->finobjsur = g->finobj; /* all news are survivals */
1253 
1254  sweepgen(L, g, &g->tobefnz, NULL, &dummy);
1255  finishgencycle(L, g);
1256 }
1257 
1258 
1259 /*
1260 ** Clears all gray lists, sweeps objects, and prepare sublists to enter
1261 ** generational mode. The sweeps remove dead objects and turn all
1262 ** surviving objects to old. Threads go back to 'grayagain'; everything
1263 ** else is turned black (not in any gray list).
1264 */
1265 static void atomic2gen (lua_State *L, global_State *g) {
1266  cleargraylists(g);
1267  /* sweep all elements making them old */
1268  g->gcstate = GCSswpallgc;
1269  sweep2old(L, &g->allgc);
1270  /* everything alive now is old */
1271  g->reallyold = g->old1 = g->survival = g->allgc;
1272  g->firstold1 = NULL; /* there are no OLD1 objects anywhere */
1273 
1274  /* repeat for 'finobj' lists */
1275  sweep2old(L, &g->finobj);
1276  g->finobjrold = g->finobjold1 = g->finobjsur = g->finobj;
1277 
1278  sweep2old(L, &g->tobefnz);
1279 
1280  g->gckind = KGC_GEN;
1281  g->lastatomic = 0;
1282  g->GCestimate = gettotalbytes(g); /* base for memory control */
1283  finishgencycle(L, g);
1284 }
1285 
1286 
1287 /*
1288 ** Enter generational mode. Must go until the end of an atomic cycle
1289 ** to ensure that all objects are correctly marked and weak tables
1290 ** are cleared. Then, turn all objects into old and finishes the
1291 ** collection.
1292 */
1294  lu_mem numobjs;
1295  luaC_runtilstate(L, bitmask(GCSpause)); /* prepare to start a new cycle */
1296  luaC_runtilstate(L, bitmask(GCSpropagate)); /* start new cycle */
1297  numobjs = atomic(L); /* propagates all and then do the atomic stuff */
1298  atomic2gen(L, g);
1299  return numobjs;
1300 }
1301 
1302 
1303 /*
1304 ** Enter incremental mode. Turn all objects white, make all
1305 ** intermediate lists point to NULL (to avoid invalid pointers),
1306 ** and go to the pause state.
1307 */
1308 static void enterinc (global_State *g) {
1309  whitelist(g, g->allgc);
1310  g->reallyold = g->old1 = g->survival = NULL;
1311  whitelist(g, g->finobj);
1312  whitelist(g, g->tobefnz);
1313  g->finobjrold = g->finobjold1 = g->finobjsur = NULL;
1314  g->gcstate = GCSpause;
1315  g->gckind = KGC_INC;
1316  g->lastatomic = 0;
1317 }
1318 
1319 
1320 /*
1321 ** Change collector mode to 'newmode'.
1322 */
1323 void luaC_changemode (lua_State *L, int newmode) {
1324  global_State *g = G(L);
1325  if (newmode != g->gckind) {
1326  if (newmode == KGC_GEN) /* entering generational mode? */
1327  entergen(L, g);
1328  else
1329  enterinc(g); /* entering incremental mode */
1330  }
1331  g->lastatomic = 0;
1332 }
1333 
1334 
1335 /*
1336 ** Does a full collection in generational mode.
1337 */
1339  enterinc(g);
1340  return entergen(L, g);
1341 }
1342 
1343 
1344 /*
1345 ** Set debt for the next minor collection, which will happen when
1346 ** memory grows 'genminormul'%.
1347 */
1348 static void setminordebt (global_State *g) {
1349  luaE_setdebt(g, -(cast(l_mem, (gettotalbytes(g) / 100)) * g->genminormul));
1350 }
1351 
1352 
1353 /*
1354 ** Does a major collection after last collection was a "bad collection".
1355 **
1356 ** When the program is building a big structure, it allocates lots of
1357 ** memory but generates very little garbage. In those scenarios,
1358 ** the generational mode just wastes time doing small collections, and
1359 ** major collections are frequently what we call a "bad collection", a
1360 ** collection that frees too few objects. To avoid the cost of switching
1361 ** between generational mode and the incremental mode needed for full
1362 ** (major) collections, the collector tries to stay in incremental mode
1363 ** after a bad collection, and to switch back to generational mode only
1364 ** after a "good" collection (one that traverses less than 9/8 objects
1365 ** of the previous one).
1366 ** The collector must choose whether to stay in incremental mode or to
1367 ** switch back to generational mode before sweeping. At this point, it
1368 ** does not know the real memory in use, so it cannot use memory to
1369 ** decide whether to return to generational mode. Instead, it uses the
1370 ** number of objects traversed (returned by 'atomic') as a proxy. The
1371 ** field 'g->lastatomic' keeps this count from the last collection.
1372 ** ('g->lastatomic != 0' also means that the last collection was bad.)
1373 */
1374 static void stepgenfull (lua_State *L, global_State *g) {
1375  lu_mem newatomic; /* count of traversed objects */
1376  lu_mem lastatomic = g->lastatomic; /* count from last collection */
1377  if (g->gckind == KGC_GEN) /* still in generational mode? */
1378  enterinc(g); /* enter incremental mode */
1379  luaC_runtilstate(L, bitmask(GCSpropagate)); /* start new cycle */
1380  newatomic = atomic(L); /* mark everybody */
1381  if (newatomic < lastatomic + (lastatomic >> 3)) { /* good collection? */
1382  atomic2gen(L, g); /* return to generational mode */
1383  setminordebt(g);
1384  }
1385  else { /* another bad collection; stay in incremental mode */
1386  g->GCestimate = gettotalbytes(g); /* first estimate */;
1387  entersweep(L);
1388  luaC_runtilstate(L, bitmask(GCSpause)); /* finish collection */
1389  setpause(g);
1390  g->lastatomic = newatomic;
1391  }
1392 }
1393 
1394 
1395 /*
1396 ** Does a generational "step".
1397 ** Usually, this means doing a minor collection and setting the debt to
1398 ** make another collection when memory grows 'genminormul'% larger.
1399 **
1400 ** However, there are exceptions. If memory grows 'genmajormul'%
1401 ** larger than it was at the end of the last major collection (kept
1402 ** in 'g->GCestimate'), the function does a major collection. At the
1403 ** end, it checks whether the major collection was able to free a
1404 ** decent amount of memory (at least half the growth in memory since
1405 ** previous major collection). If so, the collector keeps its state,
1406 ** and the next collection will probably be minor again. Otherwise,
1407 ** we have what we call a "bad collection". In that case, set the field
1408 ** 'g->lastatomic' to signal that fact, so that the next collection will
1409 ** go to 'stepgenfull'.
1410 **
1411 ** 'GCdebt <= 0' means an explicit call to GC step with "size" zero;
1412 ** in that case, do a minor collection.
1413 */
1414 static void genstep (lua_State *L, global_State *g) {
1415  if (g->lastatomic != 0) /* last collection was a bad one? */
1416  stepgenfull(L, g); /* do a full step */
1417  else {
1418  lu_mem majorbase = g->GCestimate; /* memory after last major collection */
1419  lu_mem majorinc = (majorbase / 100) * getgcparam(g->genmajormul);
1420  if (g->GCdebt > 0 && gettotalbytes(g) > majorbase + majorinc) {
1421  lu_mem numobjs = fullgen(L, g); /* do a major collection */
1422  if (gettotalbytes(g) < majorbase + (majorinc / 2)) {
1423  /* collected at least half of memory growth since last major
1424  collection; keep doing minor collections */
1425  setminordebt(g);
1426  }
1427  else { /* bad collection */
1428  g->lastatomic = numobjs; /* signal that last collection was bad */
1429  setpause(g); /* do a long wait for next (major) collection */
1430  }
1431  }
1432  else { /* regular case; do a minor collection */
1433  youngcollection(L, g);
1434  setminordebt(g);
1435  g->GCestimate = majorbase; /* preserve base value */
1436  }
1437  }
1439 }
1440 
1441 /* }====================================================== */
1442 
1443 
1444 /*
1445 ** {======================================================
1446 ** GC control
1447 ** =======================================================
1448 */
1449 
1450 
1451 /*
1452 ** Set the "time" to wait before starting a new GC cycle; cycle will
1453 ** start when memory use hits the threshold of ('estimate' * pause /
1454 ** PAUSEADJ). (Division by 'estimate' should be OK: it cannot be zero,
1455 ** because Lua cannot even start with less than PAUSEADJ bytes).
1456 */
1457 static void setpause (global_State *g) {
1458  l_mem threshold, debt;
1459  int pause = getgcparam(g->gcpause);
1460  l_mem estimate = g->GCestimate / PAUSEADJ; /* adjust 'estimate' */
1461  lua_assert(estimate > 0);
1462  threshold = (pause < MAX_LMEM / estimate) /* overflow? */
1463  ? estimate * pause /* no overflow */
1464  : MAX_LMEM; /* overflow; truncate to maximum */
1465  debt = gettotalbytes(g) - threshold;
1466  if (debt > 0) debt = 0;
1467  luaE_setdebt(g, debt);
1468 }
1469 
1470 
1471 /*
1472 ** Enter first sweep phase.
1473 ** The call to 'sweeptolive' makes the pointer point to an object
1474 ** inside the list (instead of to the header), so that the real sweep do
1475 ** not need to skip objects created between "now" and the start of the
1476 ** real sweep.
1477 */
1478 static void entersweep (lua_State *L) {
1479  global_State *g = G(L);
1480  g->gcstate = GCSswpallgc;
1481  lua_assert(g->sweepgc == NULL);
1482  g->sweepgc = sweeptolive(L, &g->allgc);
1483 }
1484 
1485 
1486 /*
1487 ** Delete all objects in list 'p' until (but not including) object
1488 ** 'limit'.
1489 */
1490 static void deletelist (lua_State *L, GCObject *p, GCObject *limit) {
1491  while (p != limit) {
1492  GCObject *next = p->next;
1493  freeobj(L, p);
1494  p = next;
1495  }
1496 }
1497 
1498 
1499 /*
1500 ** Call all finalizers of the objects in the given Lua state, and
1501 ** then free all objects, except for the main thread.
1502 */
1504  global_State *g = G(L);
1506  separatetobefnz(g, 1); /* separate all objects with finalizers */
1507  lua_assert(g->finobj == NULL);
1509  deletelist(L, g->allgc, obj2gco(g->mainthread));
1510  deletelist(L, g->finobj, NULL);
1511  deletelist(L, g->fixedgc, NULL); /* collect fixed objects */
1512  lua_assert(g->strt.nuse == 0);
1513 }
1514 
1515 
1516 static lu_mem atomic (lua_State *L) {
1517  global_State *g = G(L);
1518  lu_mem work = 0;
1519  GCObject *origweak, *origall;
1520  GCObject *grayagain = g->grayagain; /* save original list */
1521  g->grayagain = NULL;
1522  lua_assert(g->ephemeron == NULL && g->weak == NULL);
1524  g->gcstate = GCSatomic;
1525  markobject(g, L); /* mark running thread */
1526  /* registry and global metatables may be changed by API */
1527  markvalue(g, &g->l_registry);
1528  markmt(g); /* mark global metatables */
1529  work += propagateall(g); /* empties 'gray' list */
1530  /* remark occasional upvalues of (maybe) dead threads */
1531  work += remarkupvals(g);
1532  work += propagateall(g); /* propagate changes */
1533  g->gray = grayagain;
1534  work += propagateall(g); /* traverse 'grayagain' list */
1535  convergeephemerons(g);
1536  /* at this point, all strongly accessible objects are marked. */
1537  /* Clear values from weak tables, before checking finalizers */
1538  clearbyvalues(g, g->weak, NULL);
1539  clearbyvalues(g, g->allweak, NULL);
1540  origweak = g->weak; origall = g->allweak;
1541  separatetobefnz(g, 0); /* separate objects to be finalized */
1542  work += markbeingfnz(g); /* mark objects that will be finalized */
1543  work += propagateall(g); /* remark, to propagate 'resurrection' */
1544  convergeephemerons(g);
1545  /* at this point, all resurrected objects are marked. */
1546  /* remove dead objects from weak tables */
1547  clearbykeys(g, g->ephemeron); /* clear keys from all ephemeron tables */
1548  clearbykeys(g, g->allweak); /* clear keys from all 'allweak' tables */
1549  /* clear values from resurrected weak tables */
1550  clearbyvalues(g, g->weak, origweak);
1551  clearbyvalues(g, g->allweak, origall);
1552  luaS_clearcache(g);
1553  g->currentwhite = cast_byte(otherwhite(g)); /* flip current white */
1554  lua_assert(g->gray == NULL);
1555  return work; /* estimate of slots marked by 'atomic' */
1556 }
1557 
1558 
1559 static int sweepstep (lua_State *L, global_State *g,
1560  int nextstate, GCObject **nextlist) {
1561  if (g->sweepgc) {
1562  l_mem olddebt = g->GCdebt;
1563  int count;
1564  g->sweepgc = sweeplist(L, g->sweepgc, GCSWEEPMAX, &count);
1565  g->GCestimate += g->GCdebt - olddebt; /* update estimate */
1566  return count;
1567  }
1568  else { /* enter next state */
1569  g->gcstate = nextstate;
1570  g->sweepgc = nextlist;
1571  return 0; /* no work done */
1572  }
1573 }
1574 
1575 
1577  global_State *g = G(L);
1578  switch (g->gcstate) {
1579  case GCSpause: {
1580  restartcollection(g);
1581  g->gcstate = GCSpropagate;
1582  return 1;
1583  }
1584  case GCSpropagate: {
1585  if (g->gray == NULL) { /* no more gray objects? */
1586  g->gcstate = GCSenteratomic; /* finish propagate phase */
1587  return 0;
1588  }
1589  else
1590  return propagatemark(g); /* traverse one gray object */
1591  }
1592  case GCSenteratomic: {
1593  lu_mem work = atomic(L); /* work is what was traversed by 'atomic' */
1594  entersweep(L);
1595  g->GCestimate = gettotalbytes(g); /* first estimate */;
1596  return work;
1597  }
1598  case GCSswpallgc: { /* sweep "regular" objects */
1599  return sweepstep(L, g, GCSswpfinobj, &g->finobj);
1600  }
1601  case GCSswpfinobj: { /* sweep objects with finalizers */
1602  return sweepstep(L, g, GCSswptobefnz, &g->tobefnz);
1603  }
1604  case GCSswptobefnz: { /* sweep objects to be finalized */
1605  return sweepstep(L, g, GCSswpend, NULL);
1606  }
1607  case GCSswpend: { /* finish sweeps */
1608  checkSizes(L, g);
1609  g->gcstate = GCScallfin;
1610  return 0;
1611  }
1612  case GCScallfin: { /* call remaining finalizers */
1613  if (g->tobefnz && !g->gcemergency) {
1614  int n = runafewfinalizers(L, GCFINMAX);
1615  return n * GCFINALIZECOST;
1616  }
1617  else { /* emergency mode or no more finalizers */
1618  g->gcstate = GCSpause; /* finish collection */
1619  return 0;
1620  }
1621  }
1622  default: lua_assert(0); return 0;
1623  }
1624 }
1625 
1626 
1627 /*
1628 ** advances the garbage collector until it reaches a state allowed
1629 ** by 'statemask'
1630 */
1631 void luaC_runtilstate (lua_State *L, int statesmask) {
1632  global_State *g = G(L);
1633  while (!testbit(statesmask, g->gcstate))
1634  singlestep(L);
1635 }
1636 
1637 
1638 /*
1639 ** Performs a basic incremental step. The debt and step size are
1640 ** converted from bytes to "units of work"; then the function loops
1641 ** running single steps until adding that many units of work or
1642 ** finishing a cycle (pause state). Finally, it sets the debt that
1643 ** controls when next step will be performed.
1644 */
1645 static void incstep (lua_State *L, global_State *g) {
1646  int stepmul = (getgcparam(g->gcstepmul) | 1); /* avoid division by 0 */
1647  l_mem debt = (g->GCdebt / WORK2MEM) * stepmul;
1648  l_mem stepsize = (g->gcstepsize <= log2maxs(l_mem))
1649  ? ((cast(l_mem, 1) << g->gcstepsize) / WORK2MEM) * stepmul
1650  : MAX_LMEM; /* overflow; keep maximum value */
1651  do { /* repeat until pause or enough "credit" (negative debt) */
1652  lu_mem work = singlestep(L); /* perform one single step */
1653  debt -= work;
1654  } while (debt > -stepsize && g->gcstate != GCSpause);
1655  if (g->gcstate == GCSpause)
1656  setpause(g); /* pause until next cycle */
1657  else {
1658  debt = (debt / stepmul) * WORK2MEM; /* convert 'work units' to bytes */
1659  luaE_setdebt(g, debt);
1660  }
1661 }
1662 
1663 /*
1664 ** performs a basic GC step if collector is running
1665 */
1667  global_State *g = G(L);
1668  lua_assert(!g->gcemergency);
1669  if (g->gcrunning) { /* running? */
1670  if(isdecGCmodegen(g))
1671  genstep(L, g);
1672  else
1673  incstep(L, g);
1674  }
1675 }
1676 
1677 
1678 /*
1679 ** Perform a full collection in incremental mode.
1680 ** Before running the collection, check 'keepinvariant'; if it is true,
1681 ** there may be some objects marked as black, so the collector has
1682 ** to sweep all objects to turn them back to white (as white has not
1683 ** changed, nothing will be collected).
1684 */
1685 static void fullinc (lua_State *L, global_State *g) {
1686  if (keepinvariant(g)) /* black objects? */
1687  entersweep(L); /* sweep everything to turn them back to white */
1688  /* finish any pending sweep phase to start a new cycle */
1690  luaC_runtilstate(L, bitmask(GCScallfin)); /* run up to finalizers */
1691  /* estimate must be correct after a full GC cycle */
1693  luaC_runtilstate(L, bitmask(GCSpause)); /* finish collection */
1694  setpause(g);
1695 }
1696 
1697 
1698 /*
1699 ** Performs a full GC cycle; if 'isemergency', set a flag to avoid
1700 ** some operations which could change the interpreter state in some
1701 ** unexpected ways (running finalizers and shrinking some structures).
1702 */
1703 void luaC_fullgc (lua_State *L, int isemergency) {
1704  global_State *g = G(L);
1705  lua_assert(!g->gcemergency);
1706  g->gcemergency = isemergency; /* set flag */
1707  if (g->gckind == KGC_INC)
1708  fullinc(L, g);
1709  else
1710  fullgen(L, g);
1711  g->gcemergency = 0;
1712 }
1713 
1714 /* }====================================================== */
1715 
1716 
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Definition: lstate.h:238
UpVal * upvals[1]
Definition: lobject.h:634
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Definition: llimits.h:162
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Definition: lstate.h:225
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Definition: lobject.h:753
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Definition: lgc.cpp:942
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Definition: lgc.cpp:339
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Definition: lstate.h:240
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Definition: lgc.cpp:736
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Definition: lgc.cpp:146
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Definition: lgc.cpp:361
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Definition: lobject.h:540
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Definition: lstring.cpp:85
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Definition: lobject.h:370
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Definition: lstate.h:147
static void fullinc(lua_State *L, global_State *g)
Definition: lgc.cpp:1685
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Definition: lobject.h:547
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Definition: lgc.cpp:1631
GCObject * luaC_newobj(lua_State *L, int tt, size_t sz)
Definition: lgc.cpp:258
#define GCSWEEPMAX
Definition: lgc.cpp:35
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Definition: lgc.cpp:185
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Definition: lgc.cpp:1348
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Definition: lobject.h:195
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Definition: llimits.h:30
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Definition: lobject.h:443
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Definition: lstate.h:278
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Definition: lstate.h:232
static void checkSizes(lua_State *L, global_State *g)
Definition: lgc.cpp:863
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Definition: lstate.h:281
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Definition: llimits.h:31
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Definition: lgc.cpp:208
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Definition: lstate.h:351
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Definition: lmem.h:55
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Definition: lua.h:69
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Definition: lgc.cpp:952
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Definition: llimits.h:36
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Definition: lstate.h:332
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Definition: lgc.cpp:1645
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Definition: lstate.h:152
Definition: lobject.h:606
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Definition: lgc.h:67
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Definition: lgc.h:99
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Definition: lstate.h:260
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Definition: lobject.h:609
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Definition: llimits.h:125
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Definition: lfunc.h:14
int luaD_pcall(lua_State *L, Pfunc func, void *u, ptrdiff_t old_top, ptrdiff_t ef)
Definition: ldo.cpp:777
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Definition: lobject.h:430
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Definition: lobject.h:338
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Definition: lstate.h:280
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Definition: ltable.h:31
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Definition: lmem.h:64
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Definition: lgc.cpp:397
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Definition: lobject.h:367
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Definition: lstate.h:230
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Definition: lstate.h:256
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Definition: lobject.h:445
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Definition: lgc.cpp:557
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Definition: lgc.h:38
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Definition: lgc.cpp:148
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Definition: llimits.h:60
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Definition: lgc.h:65
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Definition: lgc.cpp:816
static GCObject ** sweepgen(lua_State *L, global_State *g, GCObject **p, GCObject *limit, GCObject **pfirstold1)
Definition: lgc.cpp:1088
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Definition: lgc.cpp:122
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Definition: lgc.cpp:652
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Definition: lgc.cpp:71
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Definition: lobject.h:339
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Definition: lgc.h:96
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Definition: lstate.h:338
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Definition: lgc.cpp:1490
#define luaM_free(L, b)
Definition: lmem.h:56
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Definition: lobject.h:506
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Definition: lgc.cpp:878
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Definition: lgc.cpp:329
TValue * array
Definition: lobject.h:719
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Definition: lstate.h:334
GCObject * gclist
Definition: lobject.h:444
static void traversestrongtable(global_State *g, Table *h)
Definition: lgc.cpp:517
static void convergeephemerons(global_State *g)
Definition: lgc.cpp:683
struct Table * mt[LUA_NUMTAGS]
Definition: lstate.h:263
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Definition: lgc.cpp:97
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Definition: lstate.h:255
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Definition: lgc.cpp:40
Definition: ltm.h:22
#define G_OLD0
Definition: lgc.h:108
static lu_mem atomic(lua_State *L)
Definition: lgc.cpp:1516
struct Proto ** p
Definition: lobject.h:546
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Definition: lstate.h:245
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Definition: lgc.cpp:899
GCObject * gray
Definition: lstate.h:243
static void markold(global_State *g, GCObject *from, GCObject *to)
Definition: lgc.cpp:1194
const TValue * luaT_gettmbyobj(lua_State *L, const TValue *o, TMS event)
Definition: ltm.cpp:71
#define UNUSED(x)
Definition: global.hpp:30
static int traversethread(global_State *g, lua_State *th)
Definition: lgc.cpp:621
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Definition: lstate.cpp:422
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Definition: llimits.h:101
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Definition: function.cpp:940
static void reallymarkobject(global_State *g, GCObject *o)
Definition: lgc.cpp:291
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Definition: lgc.cpp:243
LUAI_FUNC unsigned int luaH_realasize(const Table *t)
Definition: ltable.cpp:222
mock_party p
#define GCSpropagate
Definition: lgc.h:31
#define gco2upv(o)
Definition: lstate.h:340
#define LUA_NUMTAGS
Definition: lua.h:415
#define sizeudata(nuv, nb)
Definition: lobject.h:476
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Definition: lgc.cpp:1478
int size
Definition: lstate.h:153
struct Table * metatable
Definition: lobject.h:722
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Definition: lstate.h:241
#define G_TOUCHED2
Definition: lgc.h:112
double g
Definition: astarsearch.cpp:64
#define linkobjgclist(o, p)
Definition: lgc.cpp:159
static void finishgencycle(lua_State *L, global_State *g)
Definition: lgc.cpp:1210
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Definition: astarsearch.cpp:65
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Definition: ltable.cpp:608
#define gco2ts(o)
Definition: lstate.h:330
int sizek
Definition: lobject.h:536
GCObject * survival
Definition: lstate.h:251
GCObject * grayagain
Definition: lstate.h:244
#define G_OLD1
Definition: lgc.h:109
UpVal * openupval
Definition: lstate.h:283
static void freeupval(lua_State *L, UpVal *uv)
Definition: lgc.cpp:757
GCObject * allweak
Definition: lstate.h:247
#define MAX_LMEM
Definition: llimits.h:50
struct lua_State * twups
Definition: lstate.h:258
struct lua_State * twups
Definition: lstate.h:285
int w
#define setage(o, a)
Definition: lgc.h:117
static int traverseproto(global_State *g, Proto *f)
Definition: lgc.cpp:572
#define LUA_VUPVAL
Definition: lobject.h:564
#define markobject(g, t)
Definition: lgc.cpp:99
#define LUA_VPROTO
Definition: lobject.h:487
static void correctpointers(global_State *g, GCObject *o)
Definition: lgc.cpp:999
GCObject * firstold1
Definition: lstate.h:254
#define gcvalueN(o)
Definition: lgc.cpp:91
static void clearbykeys(global_State *g, GCObject *l)
Definition: lgc.cpp:717
GCObject * fixedgc
Definition: lstate.h:249
static void cleargraylists(global_State *g)
Definition: lgc.cpp:388
#define isdeadm(ow, m)
Definition: lgc.h:95
TValue upvalue[1]
Definition: lobject.h:627
void luaD_callnoyield(lua_State *L, StkId func, int nResults)
Definition: ldo.cpp:565
#define savestack(L, p)
Definition: ldo.h:35
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Definition: llex.cpp:32
#define isblack(x)
Definition: lgc.h:88
#define G_NEW
Definition: lgc.h:106
static lu_mem entergen(lua_State *L, global_State *g)
Definition: lgc.cpp:1293
#define LUA_VLCL
Definition: lobject.h:568
static void clearkey(Node *n)
Definition: lgc.cpp:171
void luaC_barrierback_(lua_State *L, GCObject *o)
Definition: lgc.cpp:230
GCObject * old1
Definition: lstate.h:252
struct UpVal::@5::@6 open
#define PAUSEADJ
Definition: lgc.cpp:60
GCObject * gclist
Definition: lobject.h:723
#define keyisnil(node)
Definition: lobject.h:733
#define sizenode(t)
Definition: lobject.h:768
#define f
#define LUA_OK
Definition: lua.h:49
Definition: lobject.h:676
static void checkpointer(GCObject **p, GCObject *o)
Definition: lgc.cpp:989
static int traverseLclosure(global_State *g, LClosure *cl)
Definition: lgc.cpp:598
#define G_SURVIVAL
Definition: lgc.h:107
#define setempty(v)
Definition: lobject.h:203
#define bitmask(b)
Definition: lgc.h:63
Definition: lobject.h:439
stringtable strt
Definition: lstate.h:226
lu_byte gcstate
Definition: lstate.h:231
TString * name
Definition: lobject.h:494
static int runafewfinalizers(lua_State *L, int n)
Definition: lgc.cpp:930
union TString::@3 u
#define G_OLD
Definition: lgc.h:110
#define FINALIZEDBIT
Definition: lgc.h:78
#define KGC_INC
Definition: lstate.h:146
struct Proto * p
Definition: lobject.h:633
#define issweepphase(g)
Definition: lgc.h:42
#define svalue(o)
Definition: lobject.h:385
#define set2black(x)
Definition: lgc.cpp:79
static void correctgraylists(global_State *g)
Definition: lgc.cpp:1178
#define notm(tm)
Definition: ltm.h:61
#define isintwups(L)
Definition: lfunc.h:22
unsigned int alimit
Definition: lobject.h:718
void luaC_fullgc(lua_State *L, int isemergency)
Definition: lgc.cpp:1703
#define isold(o)
Definition: lgc.h:118
int sizeupvalues
Definition: lobject.h:535
#define gckeyN(n)
Definition: lobject.h:744
#define resetbit(x, b)
Definition: lgc.h:66
void luaF_freeproto(lua_State *L, Proto *f)
Definition: lfunc.cpp:273
lu_byte gcemergency
Definition: lstate.h:236
#define stacksize(th)
Definition: lstate.h:142
TValue * k
Definition: lobject.h:544
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Definition: lgc.cpp:1308
#define sizeLclosure(n)
Definition: lfunc.h:17
static int sweepstep(lua_State *L, global_State *g, int nextstate, GCObject **nextlist)
Definition: lgc.cpp:1559
GCObject * ephemeron
Definition: lstate.h:246
static lu_mem propagateall(global_State *g)
Definition: lgc.cpp:668
#define novariant(t)
Definition: lobject.h:78
#define GCSenteratomic
Definition: lgc.h:32
static int traverseephemeron(global_State *g, Table *h, int inv)
Definition: lgc.cpp:474
#define maskgcbits
Definition: lgc.cpp:67
static map_location::DIRECTION n
GCObject * reallyold
Definition: lstate.h:253
static GCObject ** sweeptolive(lua_State *L, GCObject **p)
Definition: lgc.cpp:843
static void separatetobefnz(global_State *g, int all)
Definition: lgc.cpp:966
lu_byte gcrunning
Definition: lstate.h:235
#define otherwhite(g)
Definition: lgc.h:94
#define isgray(x)
Definition: lgc.h:89
#define GCSswpallgc
Definition: lgc.h:34
static void freeobj(lua_State *L, GCObject *o)
Definition: lgc.cpp:764
#define G_TOUCHED1
Definition: lgc.h:111
#define LUA_VUSERDATA
Definition: lobject.h:409
lu_mem GCestimate
Definition: lstate.h:224
#define sizelstring(l)
Definition: lstring.h:26
GCObject * finobjrold
Definition: lstate.h:257
#define setobj2s(L, o1, o2)
Definition: lobject.h:129
#define EXTRA_STACK
Definition: lstate.h:137
#define set2gray(x)
Definition: lgc.cpp:75
TValue l_registry
Definition: lstate.h:227
#define luaC_white(g)
Definition: lgc.h:102