2
** $Id: lgc.c,v 2.140 2013/03/16 21:10:18 roberto Exp $
4
** See Copyright Notice in lua.h
28
** cost of sweeping one element (the size of a small object divided
29
** by some adjust for the sweep speed)
31
#define GCSWEEPCOST ((sizeof(TString) + 4) / 4)
33
/* maximum number of elements to sweep in each single step */
34
#define GCSWEEPMAX (cast_int((GCSTEPSIZE / GCSWEEPCOST) / 4))
36
/* maximum number of finalizers to call in each GC step */
37
#define GCFINALIZENUM 4
41
** macro to adjust 'stepmul': 'stepmul' is actually used like
42
** 'stepmul / STEPMULADJ' (value chosen by tests)
44
#define STEPMULADJ 200
48
** macro to adjust 'pause': 'pause' is actually used like
49
** 'pause / PAUSEADJ' (value chosen by tests)
55
** 'makewhite' erases all color bits plus the old bit and then
56
** sets only the current white bit
58
#define maskcolors (~(bit2mask(BLACKBIT, OLDBIT) | WHITEBITS))
59
#define makewhite(g,x) \
60
(gch(x)->marked = cast_byte((gch(x)->marked & maskcolors) | luaC_white(g)))
62
#define white2gray(x) resetbits(gch(x)->marked, WHITEBITS)
63
#define black2gray(x) resetbit(gch(x)->marked, BLACKBIT)
66
#define isfinalized(x) testbit(gch(x)->marked, FINALIZEDBIT)
68
#define checkdeadkey(n) lua_assert(!ttisdeadkey(gkey(n)) || ttisnil(gval(n)))
71
#define checkconsistency(obj) \
72
lua_longassert(!iscollectable(obj) || righttt(obj))
75
#define markvalue(g,o) { checkconsistency(o); \
76
if (valiswhite(o)) reallymarkobject(g,gcvalue(o)); }
78
#define markobject(g,t) { if ((t) && iswhite(obj2gco(t))) \
79
reallymarkobject(g, obj2gco(t)); }
81
static void reallymarkobject (global_State *g, GCObject *o);
85
** {======================================================
87
** =======================================================
92
** one after last element in a hash array
94
#define gnodelast(h) gnode(h, cast(size_t, sizenode(h)))
98
** link table 'h' into list pointed by 'p'
100
#define linktable(h,p) ((h)->gclist = *(p), *(p) = obj2gco(h))
104
** if key is not marked, mark its entry as dead (therefore removing it
107
static void removeentry (Node *n) {
108
lua_assert(ttisnil(gval(n)));
109
if (valiswhite(gkey(n)))
110
setdeadvalue(gkey(n)); /* unused and unmarked key; remove it */
115
** tells whether a key or value can be cleared from a weak
116
** table. Non-collectable objects are never removed from weak
117
** tables. Strings behave as `values', so are never removed too. for
118
** other objects: if really collected, cannot keep them; for objects
119
** being finalized, keep them in keys, but not in values
121
static int iscleared (global_State *g, const TValue *o) {
122
if (!iscollectable(o)) return 0;
123
else if (ttisstring(o)) {
124
markobject(g, rawtsvalue(o)); /* strings are `values', so are never weak */
127
else return iswhite(gcvalue(o));
132
** barrier that moves collector forward, that is, mark the white object
133
** being pointed by a black object.
135
void luaC_barrier_ (lua_State *L, GCObject *o, GCObject *v) {
136
global_State *g = G(L);
137
lua_assert(isblack(o) && iswhite(v) && !isdead(g, v) && !isdead(g, o));
138
lua_assert(g->gcstate != GCSpause);
139
lua_assert(gch(o)->tt != LUA_TTABLE);
140
if (keepinvariantout(g)) /* must keep invariant? */
141
reallymarkobject(g, v); /* restore invariant */
142
else { /* sweep phase */
143
lua_assert(issweepphase(g));
144
makewhite(g, o); /* mark main obj. as white to avoid other barriers */
150
** barrier that moves collector backward, that is, mark the black object
151
** pointing to a white object as gray again. (Current implementation
152
** only works for tables; access to 'gclist' is not uniform across
155
void luaC_barrierback_ (lua_State *L, GCObject *o) {
156
global_State *g = G(L);
157
lua_assert(isblack(o) && !isdead(g, o) && gch(o)->tt == LUA_TTABLE);
158
black2gray(o); /* make object gray (again) */
159
gco2t(o)->gclist = g->grayagain;
165
** barrier for prototypes. When creating first closure (cache is
166
** NULL), use a forward barrier; this may be the only closure of the
167
** prototype (if it is a "regular" function, with a single instance)
168
** and the prototype may be big, so it is better to avoid traversing
169
** it again. Otherwise, use a backward barrier, to avoid marking all
170
** possible instances.
172
LUAI_FUNC void luaC_barrierproto_ (lua_State *L, Proto *p, Closure *c) {
173
global_State *g = G(L);
174
lua_assert(isblack(obj2gco(p)));
175
if (p->cache == NULL) { /* first time? */
176
luaC_objbarrier(L, p, c);
178
else { /* use a backward barrier */
179
black2gray(obj2gco(p)); /* make prototype gray (again) */
180
p->gclist = g->grayagain;
181
g->grayagain = obj2gco(p);
187
** check color (and invariants) for an upvalue that was closed,
188
** i.e., moved into the 'allgc' list
190
void luaC_checkupvalcolor (global_State *g, UpVal *uv) {
191
GCObject *o = obj2gco(uv);
192
lua_assert(!isblack(o)); /* open upvalues are never black */
194
if (keepinvariant(g)) {
195
resetoldbit(o); /* see MOVE OLD rule */
196
gray2black(o); /* it is being visited now */
200
lua_assert(issweepphase(g));
208
** create a new collectable object (with given type and size) and link
209
** it to '*list'. 'offset' tells how many bytes to allocate before the
210
** object itself (used only by states).
212
GCObject *luaC_newobj (lua_State *L, int tt, size_t sz, GCObject **list,
214
global_State *g = G(L);
215
char *raw = cast(char *, luaM_newobject(L, novariant(tt), sz));
216
GCObject *o = obj2gco(raw + offset);
218
list = &g->allgc; /* standard list for collectable objects */
219
gch(o)->marked = luaC_white(g);
221
gch(o)->next = *list;
226
/* }====================================================== */
231
** {======================================================
233
** =======================================================
238
** mark an object. Userdata, strings, and closed upvalues are visited
239
** and turned black here. Other objects are marked gray and added
240
** to appropriate list to be visited (and turned black) later. (Open
241
** upvalues are already linked in 'headuv' list.)
243
static void reallymarkobject (global_State *g, GCObject *o) {
246
switch (gch(o)->tt) {
249
size = sizestring(gco2ts(o));
250
break; /* nothing else to mark; make it black */
252
case LUA_TUSERDATA: {
253
Table *mt = gco2u(o)->metatable;
255
markobject(g, gco2u(o)->env);
256
size = sizeudata(gco2u(o));
260
UpVal *uv = gco2uv(o);
262
if (uv->v != &uv->u.value) /* open? */
263
return; /* open upvalues remain gray */
264
size = sizeof(UpVal);
268
gco2lcl(o)->gclist = g->gray;
273
gco2ccl(o)->gclist = g->gray;
278
linktable(gco2t(o), &g->gray);
282
gco2th(o)->gclist = g->gray;
287
gco2p(o)->gclist = g->gray;
291
default: lua_assert(0); return;
294
g->GCmemtrav += size;
299
** mark metamethods for basic types
301
static void markmt (global_State *g) {
303
for (i=0; i < LUA_NUMTAGS; i++)
304
markobject(g, g->mt[i]);
309
** mark all objects in list of being-finalized
311
static void markbeingfnz (global_State *g) {
313
for (o = g->tobefnz; o != NULL; o = gch(o)->next) {
315
reallymarkobject(g, o);
321
** mark all values stored in marked open upvalues. (See comment in
324
static void remarkupvals (global_State *g) {
326
for (uv = g->uvhead.u.l.next; uv != &g->uvhead; uv = uv->u.l.next) {
327
if (isgray(obj2gco(uv)))
334
** mark root set and reset all gray lists, to start a new
335
** incremental (or full) collection
337
static void restartcollection (global_State *g) {
338
g->gray = g->grayagain = NULL;
339
g->weak = g->allweak = g->ephemeron = NULL;
340
markobject(g, g->mainthread);
341
markvalue(g, &g->l_registry);
343
markbeingfnz(g); /* mark any finalizing object left from previous cycle */
346
/* }====================================================== */
350
** {======================================================
351
** Traverse functions
352
** =======================================================
355
static void traverseweakvalue (global_State *g, Table *h) {
356
Node *n, *limit = gnodelast(h);
357
/* if there is array part, assume it may have white values (do not
358
traverse it just to check) */
359
int hasclears = (h->sizearray > 0);
360
for (n = gnode(h, 0); n < limit; n++) {
362
if (ttisnil(gval(n))) /* entry is empty? */
363
removeentry(n); /* remove it */
365
lua_assert(!ttisnil(gkey(n)));
366
markvalue(g, gkey(n)); /* mark key */
367
if (!hasclears && iscleared(g, gval(n))) /* is there a white value? */
368
hasclears = 1; /* table will have to be cleared */
372
linktable(h, &g->weak); /* has to be cleared later */
373
else /* no white values */
374
linktable(h, &g->grayagain); /* no need to clean */
378
static int traverseephemeron (global_State *g, Table *h) {
379
int marked = 0; /* true if an object is marked in this traversal */
380
int hasclears = 0; /* true if table has white keys */
381
int prop = 0; /* true if table has entry "white-key -> white-value" */
382
Node *n, *limit = gnodelast(h);
384
/* traverse array part (numeric keys are 'strong') */
385
for (i = 0; i < h->sizearray; i++) {
386
if (valiswhite(&h->array[i])) {
388
reallymarkobject(g, gcvalue(&h->array[i]));
391
/* traverse hash part */
392
for (n = gnode(h, 0); n < limit; n++) {
394
if (ttisnil(gval(n))) /* entry is empty? */
395
removeentry(n); /* remove it */
396
else if (iscleared(g, gkey(n))) { /* key is not marked (yet)? */
397
hasclears = 1; /* table must be cleared */
398
if (valiswhite(gval(n))) /* value not marked yet? */
399
prop = 1; /* must propagate again */
401
else if (valiswhite(gval(n))) { /* value not marked yet? */
403
reallymarkobject(g, gcvalue(gval(n))); /* mark it now */
407
linktable(h, &g->ephemeron); /* have to propagate again */
408
else if (hasclears) /* does table have white keys? */
409
linktable(h, &g->allweak); /* may have to clean white keys */
410
else /* no white keys */
411
linktable(h, &g->grayagain); /* no need to clean */
416
static void traversestrongtable (global_State *g, Table *h) {
417
Node *n, *limit = gnodelast(h);
419
for (i = 0; i < h->sizearray; i++) /* traverse array part */
420
markvalue(g, &h->array[i]);
421
for (n = gnode(h, 0); n < limit; n++) { /* traverse hash part */
423
if (ttisnil(gval(n))) /* entry is empty? */
424
removeentry(n); /* remove it */
426
lua_assert(!ttisnil(gkey(n)));
427
markvalue(g, gkey(n)); /* mark key */
428
markvalue(g, gval(n)); /* mark value */
434
static lu_mem traversetable (global_State *g, Table *h) {
435
const char *weakkey, *weakvalue;
436
const TValue *mode = gfasttm(g, h->metatable, TM_MODE);
437
markobject(g, h->metatable);
438
if (mode && ttisstring(mode) && /* is there a weak mode? */
439
((weakkey = strchr(svalue(mode), 'k')),
440
(weakvalue = strchr(svalue(mode), 'v')),
441
(weakkey || weakvalue))) { /* is really weak? */
442
black2gray(obj2gco(h)); /* keep table gray */
443
if (!weakkey) /* strong keys? */
444
traverseweakvalue(g, h);
445
else if (!weakvalue) /* strong values? */
446
traverseephemeron(g, h);
448
linktable(h, &g->allweak); /* nothing to traverse now */
451
traversestrongtable(g, h);
452
return sizeof(Table) + sizeof(TValue) * h->sizearray +
453
sizeof(Node) * cast(size_t, sizenode(h));
457
static int traverseproto (global_State *g, Proto *f) {
459
if (f->cache && iswhite(obj2gco(f->cache)))
460
f->cache = NULL; /* allow cache to be collected */
461
markobject(g, f->source);
462
for (i = 0; i < f->sizek; i++) /* mark literals */
463
markvalue(g, &f->k[i]);
464
for (i = 0; i < f->sizeupvalues; i++) /* mark upvalue names */
465
markobject(g, f->upvalues[i].name);
466
for (i = 0; i < f->sizep; i++) /* mark nested protos */
467
markobject(g, f->p[i]);
468
for (i = 0; i < f->sizelocvars; i++) /* mark local-variable names */
469
markobject(g, f->locvars[i].varname);
470
return sizeof(Proto) + sizeof(Instruction) * f->sizecode +
471
sizeof(Proto *) * f->sizep +
472
sizeof(TValue) * f->sizek +
473
sizeof(int) * f->sizelineinfo +
474
sizeof(LocVar) * f->sizelocvars +
475
sizeof(Upvaldesc) * f->sizeupvalues;
479
static lu_mem traverseCclosure (global_State *g, CClosure *cl) {
481
for (i = 0; i < cl->nupvalues; i++) /* mark its upvalues */
482
markvalue(g, &cl->upvalue[i]);
483
return sizeCclosure(cl->nupvalues);
486
static lu_mem traverseLclosure (global_State *g, LClosure *cl) {
488
markobject(g, cl->p); /* mark its prototype */
489
for (i = 0; i < cl->nupvalues; i++) /* mark its upvalues */
490
markobject(g, cl->upvals[i]);
491
return sizeLclosure(cl->nupvalues);
495
static lu_mem traversestack (global_State *g, lua_State *th) {
498
return 1; /* stack not completely built yet */
499
for (; o < th->top; o++)
501
if (g->gcstate == GCSatomic) { /* final traversal? */
502
StkId lim = th->stack + th->stacksize; /* real end of stack */
503
for (; o < lim; o++) /* clear not-marked stack slice */
506
return sizeof(lua_State) + sizeof(TValue) * th->stacksize;
511
** traverse one gray object, turning it to black (except for threads,
512
** which are always gray).
514
static void propagatemark (global_State *g) {
516
GCObject *o = g->gray;
517
lua_assert(isgray(o));
519
switch (gch(o)->tt) {
522
g->gray = h->gclist; /* remove from 'gray' list */
523
size = traversetable(g, h);
527
LClosure *cl = gco2lcl(o);
528
g->gray = cl->gclist; /* remove from 'gray' list */
529
size = traverseLclosure(g, cl);
533
CClosure *cl = gco2ccl(o);
534
g->gray = cl->gclist; /* remove from 'gray' list */
535
size = traverseCclosure(g, cl);
539
lua_State *th = gco2th(o);
540
g->gray = th->gclist; /* remove from 'gray' list */
541
th->gclist = g->grayagain;
542
g->grayagain = o; /* insert into 'grayagain' list */
544
size = traversestack(g, th);
549
g->gray = p->gclist; /* remove from 'gray' list */
550
size = traverseproto(g, p);
553
default: lua_assert(0); return;
555
g->GCmemtrav += size;
559
static void propagateall (global_State *g) {
560
while (g->gray) propagatemark(g);
564
static void propagatelist (global_State *g, GCObject *l) {
565
lua_assert(g->gray == NULL); /* no grays left */
567
propagateall(g); /* traverse all elements from 'l' */
571
** retraverse all gray lists. Because tables may be reinserted in other
572
** lists when traversed, traverse the original lists to avoid traversing
573
** twice the same table (which is not wrong, but inefficient)
575
static void retraversegrays (global_State *g) {
576
GCObject *weak = g->weak; /* save original lists */
577
GCObject *grayagain = g->grayagain;
578
GCObject *ephemeron = g->ephemeron;
579
g->weak = g->grayagain = g->ephemeron = NULL;
580
propagateall(g); /* traverse main gray list */
581
propagatelist(g, grayagain);
582
propagatelist(g, weak);
583
propagatelist(g, ephemeron);
587
static void convergeephemerons (global_State *g) {
591
GCObject *next = g->ephemeron; /* get ephemeron list */
592
g->ephemeron = NULL; /* tables will return to this list when traversed */
594
while ((w = next) != NULL) {
595
next = gco2t(w)->gclist;
596
if (traverseephemeron(g, gco2t(w))) { /* traverse marked some value? */
597
propagateall(g); /* propagate changes */
598
changed = 1; /* will have to revisit all ephemeron tables */
604
/* }====================================================== */
608
** {======================================================
610
** =======================================================
615
** clear entries with unmarked keys from all weaktables in list 'l' up
618
static void clearkeys (global_State *g, GCObject *l, GCObject *f) {
619
for (; l != f; l = gco2t(l)->gclist) {
621
Node *n, *limit = gnodelast(h);
622
for (n = gnode(h, 0); n < limit; n++) {
623
if (!ttisnil(gval(n)) && (iscleared(g, gkey(n)))) {
624
setnilvalue(gval(n)); /* remove value ... */
625
removeentry(n); /* and remove entry from table */
633
** clear entries with unmarked values from all weaktables in list 'l' up
636
static void clearvalues (global_State *g, GCObject *l, GCObject *f) {
637
for (; l != f; l = gco2t(l)->gclist) {
639
Node *n, *limit = gnodelast(h);
641
for (i = 0; i < h->sizearray; i++) {
642
TValue *o = &h->array[i];
643
if (iscleared(g, o)) /* value was collected? */
644
setnilvalue(o); /* remove value */
646
for (n = gnode(h, 0); n < limit; n++) {
647
if (!ttisnil(gval(n)) && iscleared(g, gval(n))) {
648
setnilvalue(gval(n)); /* remove value ... */
649
removeentry(n); /* and remove entry from table */
656
static void freeobj (lua_State *L, GCObject *o) {
657
switch (gch(o)->tt) {
658
case LUA_TPROTO: luaF_freeproto(L, gco2p(o)); break;
660
luaM_freemem(L, o, sizeLclosure(gco2lcl(o)->nupvalues));
664
luaM_freemem(L, o, sizeCclosure(gco2ccl(o)->nupvalues));
667
case LUA_TUPVAL: luaF_freeupval(L, gco2uv(o)); break;
668
case LUA_TTABLE: luaH_free(L, gco2t(o)); break;
669
case LUA_TTHREAD: luaE_freethread(L, gco2th(o)); break;
670
case LUA_TUSERDATA: luaM_freemem(L, o, sizeudata(gco2u(o))); break;
675
luaM_freemem(L, o, sizestring(gco2ts(o)));
678
default: lua_assert(0);
683
#define sweepwholelist(L,p) sweeplist(L,p,MAX_LUMEM)
684
static GCObject **sweeplist (lua_State *L, GCObject **p, lu_mem count);
688
** sweep the (open) upvalues of a thread and resize its stack and
689
** list of call-info structures.
691
static void sweepthread (lua_State *L, lua_State *L1) {
692
if (L1->stack == NULL) return; /* stack not completely built yet */
693
sweepwholelist(L, &L1->openupval); /* sweep open upvalues */
694
luaE_freeCI(L1); /* free extra CallInfo slots */
695
/* should not change the stack during an emergency gc cycle */
696
if (G(L)->gckind != KGC_EMERGENCY)
697
luaD_shrinkstack(L1);
702
** sweep at most 'count' elements from a list of GCObjects erasing dead
703
** objects, where a dead (not alive) object is one marked with the "old"
704
** (non current) white and not fixed.
705
** In non-generational mode, change all non-dead objects back to white,
706
** preparing for next collection cycle.
707
** In generational mode, keep black objects black, and also mark them as
708
** old; stop when hitting an old object, as all objects after that
709
** one will be old too.
710
** When object is a thread, sweep its list of open upvalues too.
712
static GCObject **sweeplist (lua_State *L, GCObject **p, lu_mem count) {
713
global_State *g = G(L);
714
int ow = otherwhite(g);
715
int toclear, toset; /* bits to clear and to set in all live objects */
716
int tostop; /* stop sweep when this is true */
717
if (isgenerational(g)) { /* generational mode? */
718
toclear = ~0; /* clear nothing */
719
toset = bitmask(OLDBIT); /* set the old bit of all surviving objects */
720
tostop = bitmask(OLDBIT); /* do not sweep old generation */
722
else { /* normal mode */
723
toclear = maskcolors; /* clear all color bits + old bit */
724
toset = luaC_white(g); /* make object white */
725
tostop = 0; /* do not stop */
727
while (*p != NULL && count-- > 0) {
729
int marked = gch(curr)->marked;
730
if (isdeadm(ow, marked)) { /* is 'curr' dead? */
731
*p = gch(curr)->next; /* remove 'curr' from list */
732
freeobj(L, curr); /* erase 'curr' */
735
if (testbits(marked, tostop))
736
return NULL; /* stop sweeping this list */
737
if (gch(curr)->tt == LUA_TTHREAD)
738
sweepthread(L, gco2th(curr)); /* sweep thread's upvalues */
740
gch(curr)->marked = cast_byte((marked & toclear) | toset);
741
p = &gch(curr)->next; /* go to next element */
744
return (*p == NULL) ? NULL : p;
749
** sweep a list until a live object (or end of list)
751
static GCObject **sweeptolive (lua_State *L, GCObject **p, int *n) {
756
p = sweeplist(L, p, 1);
762
/* }====================================================== */
766
** {======================================================
768
** =======================================================
771
static void checkSizes (lua_State *L) {
772
global_State *g = G(L);
773
if (g->gckind != KGC_EMERGENCY) { /* do not change sizes in emergency */
774
int hs = g->strt.size / 2; /* half the size of the string table */
775
if (g->strt.nuse < cast(lu_int32, hs)) /* using less than that half? */
776
luaS_resize(L, hs); /* halve its size */
777
luaZ_freebuffer(L, &g->buff); /* free concatenation buffer */
782
static GCObject *udata2finalize (global_State *g) {
783
GCObject *o = g->tobefnz; /* get first element */
784
lua_assert(isfinalized(o));
785
g->tobefnz = gch(o)->next; /* remove it from 'tobefnz' list */
786
gch(o)->next = g->allgc; /* return it to 'allgc' list */
788
resetbit(gch(o)->marked, SEPARATED); /* mark that it is not in 'tobefnz' */
789
lua_assert(!isold(o)); /* see MOVE OLD rule */
790
if (!keepinvariantout(g)) /* not keeping invariant? */
791
makewhite(g, o); /* "sweep" object */
796
static void dothecall (lua_State *L, void *ud) {
798
luaD_call(L, L->top - 2, 0, 0);
802
static void GCTM (lua_State *L, int propagateerrors) {
803
global_State *g = G(L);
806
setgcovalue(L, &v, udata2finalize(g));
807
tm = luaT_gettmbyobj(L, &v, TM_GC);
808
if (tm != NULL && ttisfunction(tm)) { /* is there a finalizer? */
810
lu_byte oldah = L->allowhook;
811
int running = g->gcrunning;
812
L->allowhook = 0; /* stop debug hooks during GC metamethod */
813
g->gcrunning = 0; /* avoid GC steps */
814
setobj2s(L, L->top, tm); /* push finalizer... */
815
setobj2s(L, L->top + 1, &v); /* ... and its argument */
816
L->top += 2; /* and (next line) call the finalizer */
817
status = luaD_pcall(L, dothecall, NULL, savestack(L, L->top - 2), 0);
818
L->allowhook = oldah; /* restore hooks */
819
g->gcrunning = running; /* restore state */
820
if (status != LUA_OK && propagateerrors) { /* error while running __gc? */
821
if (status == LUA_ERRRUN) { /* is there an error object? */
822
const char *msg = (ttisstring(L->top - 1))
825
luaO_pushfstring(L, "error in __gc metamethod (%s)", msg);
826
status = LUA_ERRGCMM; /* error in __gc metamethod */
828
luaD_throw(L, status); /* re-throw error */
835
** move all unreachable objects (or 'all' objects) that need
836
** finalization from list 'finobj' to list 'tobefnz' (to be finalized)
838
static void separatetobefnz (lua_State *L, int all) {
839
global_State *g = G(L);
840
GCObject **p = &g->finobj;
842
GCObject **lastnext = &g->tobefnz;
843
/* find last 'next' field in 'tobefnz' list (to add elements in its end) */
844
while (*lastnext != NULL)
845
lastnext = &gch(*lastnext)->next;
846
while ((curr = *p) != NULL) { /* traverse all finalizable objects */
847
lua_assert(!isfinalized(curr));
848
lua_assert(testbit(gch(curr)->marked, SEPARATED));
849
if (!(iswhite(curr) || all)) /* not being collected? */
850
p = &gch(curr)->next; /* don't bother with it */
852
l_setbit(gch(curr)->marked, FINALIZEDBIT); /* won't be finalized again */
853
*p = gch(curr)->next; /* remove 'curr' from 'finobj' list */
854
gch(curr)->next = *lastnext; /* link at the end of 'tobefnz' list */
856
lastnext = &gch(curr)->next;
863
** if object 'o' has a finalizer, remove it from 'allgc' list (must
864
** search the list to find it) and link it in 'finobj' list.
866
void luaC_checkfinalizer (lua_State *L, GCObject *o, Table *mt) {
867
global_State *g = G(L);
868
if (testbit(gch(o)->marked, SEPARATED) || /* obj. is already separated... */
869
isfinalized(o) || /* ... or is finalized... */
870
gfasttm(g, mt, TM_GC) == NULL) /* or has no finalizer? */
871
return; /* nothing to be done */
872
else { /* move 'o' to 'finobj' list */
874
GCheader *ho = gch(o);
875
if (g->sweepgc == &ho->next) { /* avoid removing current sweep object */
876
lua_assert(issweepphase(g));
877
g->sweepgc = sweeptolive(L, g->sweepgc, NULL);
879
/* search for pointer pointing to 'o' */
880
for (p = &g->allgc; *p != o; p = &gch(*p)->next) { /* empty */ }
881
*p = ho->next; /* remove 'o' from root list */
882
ho->next = g->finobj; /* link it in list 'finobj' */
884
l_setbit(ho->marked, SEPARATED); /* mark it as such */
885
if (!keepinvariantout(g)) /* not keeping invariant? */
886
makewhite(g, o); /* "sweep" object */
888
resetoldbit(o); /* see MOVE OLD rule */
892
/* }====================================================== */
896
** {======================================================
898
** =======================================================
903
** set a reasonable "time" to wait before starting a new GC cycle;
904
** cycle will start when memory use hits threshold
906
static void setpause (global_State *g, l_mem estimate) {
907
l_mem debt, threshold;
908
estimate = estimate / PAUSEADJ; /* adjust 'estimate' */
909
threshold = (g->gcpause < MAX_LMEM / estimate) /* overflow? */
910
? estimate * g->gcpause /* no overflow */
911
: MAX_LMEM; /* overflow; truncate to maximum */
912
debt = -cast(l_mem, threshold - gettotalbytes(g));
913
luaE_setdebt(g, debt);
917
#define sweepphases \
918
(bitmask(GCSsweepstring) | bitmask(GCSsweepudata) | bitmask(GCSsweep))
922
** enter first sweep phase (strings) and prepare pointers for other
923
** sweep phases. The calls to 'sweeptolive' make pointers point to an
924
** object inside the list (instead of to the header), so that the real
925
** sweep do not need to skip objects created between "now" and the start
926
** of the real sweep.
927
** Returns how many objects it swept.
929
static int entersweep (lua_State *L) {
930
global_State *g = G(L);
932
g->gcstate = GCSsweepstring;
933
lua_assert(g->sweepgc == NULL && g->sweepfin == NULL);
934
/* prepare to sweep strings, finalizable objects, and regular objects */
936
g->sweepfin = sweeptolive(L, &g->finobj, &n);
937
g->sweepgc = sweeptolive(L, &g->allgc, &n);
945
void luaC_changemode (lua_State *L, int mode) {
946
global_State *g = G(L);
947
if (mode == g->gckind) return; /* nothing to change */
948
if (mode == KGC_GEN) { /* change to generational mode */
949
/* make sure gray lists are consistent */
950
luaC_runtilstate(L, bitmask(GCSpropagate));
951
g->GCestimate = gettotalbytes(g);
954
else { /* change to incremental mode */
955
/* sweep all objects to turn them back to white
956
(as white has not changed, nothing extra will be collected) */
957
g->gckind = KGC_NORMAL;
959
luaC_runtilstate(L, ~sweepphases);
965
** call all pending finalizers
967
static void callallpendingfinalizers (lua_State *L, int propagateerrors) {
968
global_State *g = G(L);
970
resetoldbit(g->tobefnz);
971
GCTM(L, propagateerrors);
976
void luaC_freeallobjects (lua_State *L) {
977
global_State *g = G(L);
979
separatetobefnz(L, 1); /* separate all objects with finalizers */
980
lua_assert(g->finobj == NULL);
981
callallpendingfinalizers(L, 0);
982
g->currentwhite = WHITEBITS; /* this "white" makes all objects look dead */
983
g->gckind = KGC_NORMAL;
984
sweepwholelist(L, &g->finobj); /* finalizers can create objs. in 'finobj' */
985
sweepwholelist(L, &g->allgc);
986
for (i = 0; i < g->strt.size; i++) /* free all string lists */
987
sweepwholelist(L, &g->strt.hash[i]);
988
lua_assert(g->strt.nuse == 0);
992
static l_mem atomic (lua_State *L) {
993
global_State *g = G(L);
994
l_mem work = -cast(l_mem, g->GCmemtrav); /* start counting work */
995
GCObject *origweak, *origall;
996
lua_assert(!iswhite(obj2gco(g->mainthread)));
997
markobject(g, L); /* mark running thread */
998
/* registry and global metatables may be changed by API */
999
markvalue(g, &g->l_registry);
1000
markmt(g); /* mark basic metatables */
1001
/* remark occasional upvalues of (maybe) dead threads */
1003
propagateall(g); /* propagate changes */
1004
work += g->GCmemtrav; /* stop counting (do not (re)count grays) */
1005
/* traverse objects caught by write barrier and by 'remarkupvals' */
1007
work -= g->GCmemtrav; /* restart counting */
1008
convergeephemerons(g);
1009
/* at this point, all strongly accessible objects are marked. */
1010
/* clear values from weak tables, before checking finalizers */
1011
clearvalues(g, g->weak, NULL);
1012
clearvalues(g, g->allweak, NULL);
1013
origweak = g->weak; origall = g->allweak;
1014
work += g->GCmemtrav; /* stop counting (objects being finalized) */
1015
separatetobefnz(L, 0); /* separate objects to be finalized */
1016
markbeingfnz(g); /* mark objects that will be finalized */
1017
propagateall(g); /* remark, to propagate `preserveness' */
1018
work -= g->GCmemtrav; /* restart counting */
1019
convergeephemerons(g);
1020
/* at this point, all resurrected objects are marked. */
1021
/* remove dead objects from weak tables */
1022
clearkeys(g, g->ephemeron, NULL); /* clear keys from all ephemeron tables */
1023
clearkeys(g, g->allweak, NULL); /* clear keys from all allweak tables */
1024
/* clear values from resurrected weak tables */
1025
clearvalues(g, g->weak, origweak);
1026
clearvalues(g, g->allweak, origall);
1027
g->currentwhite = cast_byte(otherwhite(g)); /* flip current white */
1028
work += g->GCmemtrav; /* complete counting */
1029
return work; /* estimate of memory marked by 'atomic' */
1033
static lu_mem singlestep (lua_State *L) {
1034
global_State *g = G(L);
1035
switch (g->gcstate) {
1037
/* start to count memory traversed */
1038
g->GCmemtrav = g->strt.size * sizeof(GCObject*);
1039
lua_assert(!isgenerational(g));
1040
restartcollection(g);
1041
g->gcstate = GCSpropagate;
1042
return g->GCmemtrav;
1044
case GCSpropagate: {
1046
lu_mem oldtrav = g->GCmemtrav;
1048
return g->GCmemtrav - oldtrav; /* memory traversed in this step */
1050
else { /* no more `gray' objects */
1053
g->gcstate = GCSatomic; /* finish mark phase */
1054
g->GCestimate = g->GCmemtrav; /* save what was counted */;
1055
work = atomic(L); /* add what was traversed by 'atomic' */
1056
g->GCestimate += work; /* estimate of total memory traversed */
1058
return work + sw * GCSWEEPCOST;
1061
case GCSsweepstring: {
1063
for (i = 0; i < GCSWEEPMAX && g->sweepstrgc + i < g->strt.size; i++)
1064
sweepwholelist(L, &g->strt.hash[g->sweepstrgc + i]);
1066
if (g->sweepstrgc >= g->strt.size) /* no more strings to sweep? */
1067
g->gcstate = GCSsweepudata;
1068
return i * GCSWEEPCOST;
1070
case GCSsweepudata: {
1072
g->sweepfin = sweeplist(L, g->sweepfin, GCSWEEPMAX);
1073
return GCSWEEPMAX*GCSWEEPCOST;
1076
g->gcstate = GCSsweep;
1082
g->sweepgc = sweeplist(L, g->sweepgc, GCSWEEPMAX);
1083
return GCSWEEPMAX*GCSWEEPCOST;
1086
/* sweep main thread */
1087
GCObject *mt = obj2gco(g->mainthread);
1088
sweeplist(L, &mt, 1);
1090
g->gcstate = GCSpause; /* finish collection */
1094
default: lua_assert(0); return 0;
1100
** advances the garbage collector until it reaches a state allowed
1103
void luaC_runtilstate (lua_State *L, int statesmask) {
1104
global_State *g = G(L);
1105
while (!testbit(statesmask, g->gcstate))
1110
static void generationalcollection (lua_State *L) {
1111
global_State *g = G(L);
1112
lua_assert(g->gcstate == GCSpropagate);
1113
if (g->GCestimate == 0) { /* signal for another major collection? */
1114
luaC_fullgc(L, 0); /* perform a full regular collection */
1115
g->GCestimate = gettotalbytes(g); /* update control */
1118
lu_mem estimate = g->GCestimate;
1119
luaC_runtilstate(L, bitmask(GCSpause)); /* run complete (minor) cycle */
1120
g->gcstate = GCSpropagate; /* skip restart */
1121
if (gettotalbytes(g) > (estimate / 100) * g->gcmajorinc)
1122
g->GCestimate = 0; /* signal for a major collection */
1124
g->GCestimate = estimate; /* keep estimate from last major coll. */
1127
setpause(g, gettotalbytes(g));
1128
lua_assert(g->gcstate == GCSpropagate);
1132
static void incstep (lua_State *L) {
1133
global_State *g = G(L);
1134
l_mem debt = g->GCdebt;
1135
int stepmul = g->gcstepmul;
1136
if (stepmul < 40) stepmul = 40; /* avoid ridiculous low values (and 0) */
1137
/* convert debt from Kb to 'work units' (avoid zero debt and overflows) */
1138
debt = (debt / STEPMULADJ) + 1;
1139
debt = (debt < MAX_LMEM / stepmul) ? debt * stepmul : MAX_LMEM;
1140
do { /* always perform at least one single step */
1141
lu_mem work = singlestep(L); /* do some work */
1143
} while (debt > -GCSTEPSIZE && g->gcstate != GCSpause);
1144
if (g->gcstate == GCSpause)
1145
setpause(g, g->GCestimate); /* pause until next cycle */
1147
debt = (debt / stepmul) * STEPMULADJ; /* convert 'work units' to Kb */
1148
luaE_setdebt(g, debt);
1154
** performs a basic GC step
1156
void luaC_forcestep (lua_State *L) {
1157
global_State *g = G(L);
1159
if (isgenerational(g)) generationalcollection(L);
1161
/* run a few finalizers (or all of them at the end of a collect cycle) */
1162
for (i = 0; g->tobefnz && (i < GCFINALIZENUM || g->gcstate == GCSpause); i++)
1163
GCTM(L, 1); /* call one finalizer */
1168
** performs a basic GC step only if collector is running
1170
void luaC_step (lua_State *L) {
1171
global_State *g = G(L);
1172
if (g->gcrunning) luaC_forcestep(L);
1173
else luaE_setdebt(g, -GCSTEPSIZE); /* avoid being called too often */
1179
** performs a full GC cycle; if "isemergency", does not call
1180
** finalizers (which could change stack positions)
1182
void luaC_fullgc (lua_State *L, int isemergency) {
1183
global_State *g = G(L);
1184
int origkind = g->gckind;
1185
lua_assert(origkind != KGC_EMERGENCY);
1186
if (isemergency) /* do not run finalizers during emergency GC */
1187
g->gckind = KGC_EMERGENCY;
1189
g->gckind = KGC_NORMAL;
1190
callallpendingfinalizers(L, 1);
1192
if (keepinvariant(g)) { /* may there be some black objects? */
1193
/* must sweep all objects to turn them back to white
1194
(as white has not changed, nothing will be collected) */
1197
/* finish any pending sweep phase to start a new cycle */
1198
luaC_runtilstate(L, bitmask(GCSpause));
1199
luaC_runtilstate(L, ~bitmask(GCSpause)); /* start new collection */
1200
luaC_runtilstate(L, bitmask(GCSpause)); /* run entire collection */
1201
if (origkind == KGC_GEN) { /* generational mode? */
1202
/* generational mode must be kept in propagate phase */
1203
luaC_runtilstate(L, bitmask(GCSpropagate));
1205
g->gckind = origkind;
1206
setpause(g, gettotalbytes(g));
1207
if (!isemergency) /* do not run finalizers during emergency GC */
1208
callallpendingfinalizers(L, 1);
1211
/* }====================================================== */
added
removed
tests/lua/src/lgc.c
