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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 : 58857 : static GCObject **getgclist (GCObject *o) {
126 [ + + + + : 58857 : switch (o->tt) {
+ + - ]
127 : 38634 : case LUA_VTABLE: return &gco2t(o)->gclist;
128 : 690 : case LUA_VLCL: return &gco2lcl(o)->gclist;
129 : 12930 : case LUA_VCCL: return &gco2ccl(o)->gclist;
130 : 5895 : case LUA_VTHREAD: return &gco2th(o)->gclist;
131 : 690 : case LUA_VPROTO: return &gco2p(o)->gclist;
132 : : case LUA_VUSERDATA: {
133 : 18 : Udata *u = gco2u(o);
134 : : lua_assert(u->nuvalue > 0);
135 : 18 : return &u->gclist;
136 : : }
137 : 0 : default: lua_assert(0); return 0;
138 : : }
139 : 58857 : }
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 : 30411 : static void linkgclist_ (GCObject *o, GCObject **pnext, GCObject **list) {
149 : : lua_assert(!isgray(o)); /* cannot be in a gray list */
150 : 30411 : *pnext = *list;
151 : 30411 : *list = o;
152 : 30411 : set2gray(o); /* now it is */
153 : 30411 : }
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 : 48060 : static void clearkey (Node *n) {
172 : : lua_assert(isempty(gval(n)));
173 [ + + ]: 48060 : if (keyiscollectable(n))
174 : 2 : setdeadkey(n); /* unused key; remove it */
175 : 48060 : }
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 : 0 : static int iscleared (global_State *g, const GCObject *o) {
186 [ # # ]: 0 : if (o == NULL) return 0; /* non-collectable value */
187 [ # # ]: 0 : else if (novariant(o->tt) == LUA_TSTRING) {
188 [ # # ]: 0 : markobject(g, o); /* strings are 'values', so are never weak */
189 : 0 : return 0;
190 : : }
191 : 0 : else return iswhite(o);
192 : 0 : }
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 : : */
208 : 0 : void luaC_barrier_ (lua_State *L, GCObject *o, GCObject *v) {
209 : 0 : global_State *g = G(L);
210 : : lua_assert(isblack(o) && iswhite(v) && !isdead(g, v) && !isdead(g, o));
211 [ # # ]: 0 : if (keepinvariant(g)) { /* must keep invariant? */
212 : 0 : reallymarkobject(g, v); /* restore invariant */
213 [ # # ]: 0 : if (isold(o)) {
214 : : lua_assert(!isold(v)); /* white object could not be old */
215 : 0 : setage(v, G_OLD0); /* restore generational invariant */
216 : 0 : }
217 : 0 : }
218 : : else { /* sweep phase */
219 : : lua_assert(issweepphase(g));
220 [ # # ]: 0 : if (g->gckind == KGC_INC) /* incremental mode? */
221 : 0 : makewhite(g, o); /* mark 'o' as white to avoid other barriers */
222 : : }
223 : 0 : }
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 : : */
230 : 0 : void luaC_barrierback_ (lua_State *L, GCObject *o) {
231 : 0 : 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 [ # # ]: 0 : if (getage(o) == G_TOUCHED2) /* already in gray list? */
235 : 0 : set2gray(o); /* make it gray to become touched1 */
236 : : else /* link it in 'grayagain' and paint it gray */
237 : 0 : linkobjgclist(o, g->grayagain);
238 [ # # ]: 0 : if (isold(o)) /* generational mode? */
239 : 0 : setage(o, G_TOUCHED1); /* touched in current cycle */
240 : 0 : }
241 : :
242 : :
243 : 39690 : void luaC_fix (lua_State *L, GCObject *o) {
244 : 39690 : global_State *g = G(L);
245 : : lua_assert(g->allgc == o); /* object must be 1st in 'allgc' list! */
246 : 39690 : set2gray(o); /* they will be gray forever */
247 : 39690 : setage(o, G_OLD); /* and old forever */
248 : 39690 : g->allgc = o->next; /* remove object from 'allgc' list */
249 : 39690 : o->next = g->fixedgc; /* link it to 'fixedgc' list */
250 : 39690 : g->fixedgc = o;
251 : 39690 : }
252 : :
253 : :
254 : : /*
255 : : ** create a new collectable object (with given type and size) and link
256 : : ** it to 'allgc' list.
257 : : */
258 : 201887 : GCObject *luaC_newobj (lua_State *L, int tt, size_t sz) {
259 : 201887 : global_State *g = G(L);
260 : 201887 : GCObject *o = cast(GCObject *, luaM_newobject(L, novariant(tt), sz));
261 : 201887 : o->marked = luaC_white(g);
262 : 201887 : o->tt = tt;
263 : 201887 : o->next = g->allgc;
264 : 201887 : g->allgc = o;
265 : 201887 : 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 : : */
291 : 141324 : static void reallymarkobject (global_State *g, GCObject *o) {
292 [ + + - + : 141324 : switch (o->tt) {
+ ]
293 : : case LUA_VSHRSTR:
294 : : case LUA_VLNGSTR: {
295 : 111333 : set2black(o); /* nothing to visit */
296 : 111333 : break;
297 : : }
298 : : case LUA_VUPVAL: {
299 : 165 : UpVal *uv = gco2upv(o);
300 [ - + ]: 165 : if (upisopen(uv))
301 : 0 : set2gray(uv); /* open upvalues are kept gray */
302 : : else
303 : 165 : set2black(uv); /* closed upvalues are visited here */
304 [ + - - + ]: 165 : markvalue(g, uv->v); /* mark its content */
305 : 165 : break;
306 : : }
307 : : case LUA_VUSERDATA: {
308 : 1389 : Udata *u = gco2u(o);
309 [ + + ]: 1389 : if (u->nuvalue == 0) { /* no user values? */
310 [ + + + + ]: 1380 : markobjectN(g, u->metatable); /* mark its metatable */
311 : 1380 : set2black(u); /* nothing else to mark */
312 : 1380 : break;
313 : : }
314 : : /* else... */
315 : 9 : } /* FALLTHROUGH */
316 : : case LUA_VLCL: case LUA_VCCL: case LUA_VTABLE:
317 : : case LUA_VTHREAD: case LUA_VPROTO: {
318 : 28446 : linkobjgclist(o, g->gray); /* to be visited later */
319 : 28446 : break;
320 : : }
321 : 0 : default: lua_assert(0); break;
322 : : }
323 : 141324 : }
324 : :
325 : :
326 : : /*
327 : : ** mark metamethods for basic types
328 : : */
329 : 3930 : static void markmt (global_State *g) {
330 : : int i;
331 [ + + ]: 39300 : for (i=0; i < LUA_NUMTAGS; i++)
332 [ + + + + ]: 35370 : markobjectN(g, g->mt[i]);
333 : 3930 : }
334 : :
335 : :
336 : : /*
337 : : ** mark all objects in list of being-finalized
338 : : */
339 : 3930 : static lu_mem markbeingfnz (global_State *g) {
340 : : GCObject *o;
341 : 3930 : lu_mem count = 0;
342 [ + + ]: 3939 : for (o = g->tobefnz; o != NULL; o = o->next) {
343 : 9 : count++;
344 [ - + ]: 9 : markobject(g, o);
345 : 9 : }
346 : 3930 : 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 : 1965 : static int remarkupvals (global_State *g) {
362 : : lua_State *thread;
363 : 1965 : lua_State **p = &g->twups;
364 : 1965 : int work = 0; /* estimate of how much work was done here */
365 [ - + ]: 1965 : while ((thread = *p) != NULL) {
366 : 0 : work++;
367 [ # # # # ]: 0 : if (!iswhite(thread) && thread->openupval != NULL)
368 : 0 : 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 : 0 : *p = thread->twups; /* remove thread from the list */
373 : 0 : thread->twups = thread; /* mark that it is out of list */
374 [ # # ]: 0 : for (uv = thread->openupval; uv != NULL; uv = uv->u.open.next) {
375 : : lua_assert(getage(uv) <= getage(thread));
376 : 0 : work++;
377 [ # # ]: 0 : if (!iswhite(uv)) { /* upvalue already visited? */
378 : : lua_assert(upisopen(uv) && isgray(uv));
379 [ # # # # ]: 0 : markvalue(g, uv->v); /* mark its value */
380 : 0 : }
381 : 0 : }
382 : : }
383 : : }
384 : 1965 : return work;
385 : : }
386 : :
387 : :
388 : 1965 : static void cleargraylists (global_State *g) {
389 : 1965 : g->gray = g->grayagain = NULL;
390 : 1965 : g->weak = g->allweak = g->ephemeron = NULL;
391 : 1965 : }
392 : :
393 : :
394 : : /*
395 : : ** mark root set and reset all gray lists, to start a new collection
396 : : */
397 : 1965 : static void restartcollection (global_State *g) {
398 : 1965 : cleargraylists(g);
399 [ + - ]: 1965 : markobject(g, g->mainthread);
400 [ + - + - ]: 1965 : markvalue(g, &g->l_registry);
401 : 1965 : markmt(g);
402 : 1965 : markbeingfnz(g); /* mark any finalizing object left from previous cycle */
403 : 1965 : }
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 : 19326 : static void genlink (global_State *g, GCObject *o) {
425 : : lua_assert(isblack(o));
426 [ - + ]: 19326 : if (getage(o) == G_TOUCHED1) { /* touched in this cycle? */
427 : 0 : linkobjgclist(o, g->grayagain); /* link it back in 'grayagain' */
428 : 0 : } /* everything else do not need to be linked back */
429 [ + - ]: 19326 : else if (getage(o) == G_TOUCHED2)
430 : 0 : changeage(o, G_TOUCHED2, G_OLD); /* advance age */
431 : 19326 : }
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 : : */
440 : 0 : static void traverseweakvalue (global_State *g, Table *h) {
441 : 0 : 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 : 0 : int hasclears = (h->alimit > 0);
445 [ # # ]: 0 : for (n = gnode(h, 0); n < limit; n++) { /* traverse hash part */
446 [ # # ]: 0 : if (isempty(gval(n))) /* entry is empty? */
447 : 0 : clearkey(n); /* clear its key */
448 : : else {
449 : : lua_assert(!keyisnil(n));
450 [ # # # # ]: 0 : markkey(g, n);
451 [ # # # # : 0 : if (!hasclears && iscleared(g, gcvalueN(gval(n)))) /* a white value? */
# # ]
452 : 0 : hasclears = 1; /* table will have to be cleared */
453 : : }
454 : 0 : }
455 [ # # # # ]: 0 : if (g->gcstate == GCSatomic && hasclears)
456 : 0 : linkgclist(h, g->weak); /* has to be cleared later */
457 : : else
458 : 0 : linkgclist(h, g->grayagain); /* must retraverse it in atomic phase */
459 : 0 : }
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 : 0 : static int traverseephemeron (global_State *g, Table *h, int inv) {
475 : 0 : int marked = 0; /* true if an object is marked in this traversal */
476 : 0 : int hasclears = 0; /* true if table has white keys */
477 : 0 : int hasww = 0; /* true if table has entry "white-key -> white-value" */
478 : : unsigned int i;
479 : 0 : unsigned int asize = luaH_realasize(h);
480 : 0 : unsigned int nsize = sizenode(h);
481 : : /* traverse array part */
482 [ # # ]: 0 : for (i = 0; i < asize; i++) {
483 [ # # # # ]: 0 : if (valiswhite(&h->array[i])) {
484 : 0 : marked = 1;
485 : 0 : reallymarkobject(g, gcvalue(&h->array[i]));
486 : 0 : }
487 : 0 : }
488 : : /* traverse hash part; if 'inv', traverse descending
489 : : (see 'convergeephemerons') */
490 [ # # ]: 0 : for (i = 0; i < nsize; i++) {
491 [ # # ]: 0 : Node *n = inv ? gnode(h, nsize - 1 - i) : gnode(h, i);
492 [ # # ]: 0 : if (isempty(gval(n))) /* entry is empty? */
493 : 0 : clearkey(n); /* clear its key */
494 [ # # # # ]: 0 : else if (iscleared(g, gckeyN(n))) { /* key is not marked (yet)? */
495 : 0 : hasclears = 1; /* table must be cleared */
496 [ # # # # ]: 0 : if (valiswhite(gval(n))) /* value not marked yet? */
497 : 0 : hasww = 1; /* white-white entry */
498 : 0 : }
499 [ # # # # ]: 0 : else if (valiswhite(gval(n))) { /* value not marked yet? */
500 : 0 : marked = 1;
501 : 0 : reallymarkobject(g, gcvalue(gval(n))); /* mark it now */
502 : 0 : }
503 : 0 : }
504 : : /* link table into proper list */
505 [ # # ]: 0 : if (g->gcstate == GCSpropagate)
506 : 0 : linkgclist(h, g->grayagain); /* must retraverse it in atomic phase */
507 [ # # ]: 0 : else if (hasww) /* table has white->white entries? */
508 : 0 : linkgclist(h, g->ephemeron); /* have to propagate again */
509 [ # # ]: 0 : else if (hasclears) /* table has white keys? */
510 : 0 : linkgclist(h, g->allweak); /* may have to clean white keys */
511 : : else
512 : 0 : genlink(g, obj2gco(h)); /* check whether collector still needs to see it */
513 : 0 : return marked;
514 : : }
515 : :
516 : :
517 : 19317 : static void traversestrongtable (global_State *g, Table *h) {
518 : 19317 : Node *n, *limit = gnodelast(h);
519 : : unsigned int i;
520 : 19317 : unsigned int asize = luaH_realasize(h);
521 [ + + ]: 27935 : for (i = 0; i < asize; i++) /* traverse array part */
522 [ + - + + ]: 8618 : markvalue(g, &h->array[i]);
523 [ + + ]: 192264 : for (n = gnode(h, 0); n < limit; n++) { /* traverse hash part */
524 [ + + ]: 172947 : if (isempty(gval(n))) /* entry is empty? */
525 : 48060 : clearkey(n); /* clear its key */
526 : : else {
527 : : lua_assert(!keyisnil(n));
528 [ + - + + ]: 124887 : markkey(g, n);
529 [ + + + + ]: 124887 : markvalue(g, gval(n));
530 : : }
531 : 172947 : }
532 : 19317 : genlink(g, obj2gco(h));
533 : 19317 : }
534 : :
535 : :
536 : 19317 : static lu_mem traversetable (global_State *g, Table *h) {
537 : : const char *weakkey, *weakvalue;
538 [ + + + + ]: 19317 : const TValue *mode = gfasttm(g, h->metatable, TM_MODE);
539 [ + + - + ]: 19317 : markobjectN(g, h->metatable);
540 [ - + # # : 19317 : if (mode && ttisstring(mode) && /* is there a weak mode? */
# # ]
541 : 0 : (cast_void(weakkey = strchr(svalue(mode), 'k')),
542 : 0 : cast_void(weakvalue = strchr(svalue(mode), 'v')),
543 [ # # ]: 0 : (weakkey || weakvalue))) { /* is really weak? */
544 [ # # ]: 0 : if (!weakkey) /* strong keys? */
545 : 0 : traverseweakvalue(g, h);
546 [ # # ]: 0 : else if (!weakvalue) /* strong values? */
547 : 0 : traverseephemeron(g, h, 0);
548 : : else /* all weak */
549 : 0 : linkgclist(h, g->allweak); /* nothing to traverse now */
550 : 0 : }
551 : : else /* not weak */
552 : 19317 : traversestrongtable(g, h);
553 [ + + ]: 19317 : return 1 + h->alimit + 2 * allocsizenode(h);
554 : : }
555 : :
556 : :
557 : 9 : static int traverseudata (global_State *g, Udata *u) {
558 : : int i;
559 [ - + - + ]: 9 : markobjectN(g, u->metatable); /* mark its metatable */
560 [ + + ]: 18 : for (i = 0; i < u->nuvalue; i++)
561 [ - + # # ]: 9 : markvalue(g, &u->uv[i].uv);
562 : 9 : genlink(g, obj2gco(u));
563 : 9 : 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 : 345 : static int traverseproto (global_State *g, Proto *f) {
573 : : int i;
574 [ - + + - ]: 345 : markobjectN(g, f->source);
575 [ + + ]: 2265 : for (i = 0; i < f->sizek; i++) /* mark literals */
576 [ + + + + ]: 1920 : markvalue(g, &f->k[i]);
577 [ + + ]: 1230 : for (i = 0; i < f->sizeupvalues; i++) /* mark upvalue names */
578 [ + + - + ]: 885 : markobjectN(g, f->upvalues[i].name);
579 [ - + ]: 345 : for (i = 0; i < f->sizep; i++) /* mark nested protos */
580 [ # # # # ]: 0 : markobjectN(g, f->p[i]);
581 [ + - ]: 345 : for (i = 0; i < f->sizelocvars; i++) /* mark local-variable names */
582 [ # # # # ]: 0 : markobjectN(g, f->locvars[i].varname);
583 : 345 : return 1 + f->sizek + f->sizeupvalues + f->sizep + f->sizelocvars;
584 : : }
585 : :
586 : :
587 : 6465 : static int traverseCclosure (global_State *g, CClosure *cl) {
588 : : int i;
589 [ + + ]: 12930 : for (i = 0; i < cl->nupvalues; i++) /* mark its upvalues */
590 [ + - + + ]: 6465 : markvalue(g, &cl->upvalue[i]);
591 : 6465 : 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 : : */
598 : 345 : static int traverseLclosure (global_State *g, LClosure *cl) {
599 : : int i;
600 [ - + + - ]: 345 : markobjectN(g, cl->p); /* mark its prototype */
601 [ + + ]: 690 : for (i = 0; i < cl->nupvalues; i++) { /* visit its upvalues */
602 : 345 : UpVal *uv = cl->upvals[i];
603 [ + + + - ]: 345 : markobjectN(g, uv); /* mark upvalue */
604 : 345 : }
605 : 345 : 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 : : */
621 : 3930 : static int traversethread (global_State *g, lua_State *th) {
622 : : UpVal *uv;
623 : 3930 : StkId o = th->stack;
624 [ + - + + ]: 3930 : if (isold(th) || g->gcstate == GCSpropagate)
625 : 1965 : linkgclist(th, g->grayagain); /* insert into 'grayagain' list */
626 [ + - ]: 3930 : if (o == NULL)
627 : 0 : return 1; /* stack not completely built yet */
628 : : lua_assert(g->gcstate == GCSatomic ||
629 : : th->openupval == NULL || isintwups(th));
630 [ + + ]: 21984 : for (; o < th->top; o++) /* mark live elements in the stack */
631 [ + + + + ]: 18054 : markvalue(g, s2v(o));
632 [ - + ]: 3930 : for (uv = th->openupval; uv != NULL; uv = uv->u.open.next)
633 [ # # ]: 0 : markobject(g, uv); /* open upvalues cannot be collected */
634 [ + + ]: 3930 : if (g->gcstate == GCSatomic) { /* final traversal? */
635 [ + + ]: 81363 : for (; o < th->stack_last + EXTRA_STACK; o++)
636 : 79398 : setnilvalue(s2v(o)); /* clear dead stack slice */
637 : : /* 'remarkupvals' may have removed thread from 'twups' list */
638 [ + - - + ]: 1965 : if (!isintwups(th) && th->openupval != NULL) {
639 : 0 : th->twups = g->twups; /* link it back to the list */
640 : 0 : g->twups = th;
641 : 0 : }
642 : 1965 : }
643 [ - + ]: 1965 : else if (!g->gcemergency)
644 : 1965 : luaD_shrinkstack(th); /* do not change stack in emergency cycle */
645 : 3930 : return 1 + stacksize(th);
646 : 3930 : }
647 : :
648 : :
649 : : /*
650 : : ** traverse one gray object, turning it to black.
651 : : */
652 : 30411 : static lu_mem propagatemark (global_State *g) {
653 : 30411 : GCObject *o = g->gray;
654 : 30411 : nw2black(o);
655 : 30411 : g->gray = *getgclist(o); /* remove from 'gray' list */
656 [ + + + + : 30411 : switch (o->tt) {
+ + - ]
657 : 19317 : case LUA_VTABLE: return traversetable(g, gco2t(o));
658 : 9 : case LUA_VUSERDATA: return traverseudata(g, gco2u(o));
659 : 345 : case LUA_VLCL: return traverseLclosure(g, gco2lcl(o));
660 : 6465 : case LUA_VCCL: return traverseCclosure(g, gco2ccl(o));
661 : 345 : case LUA_VPROTO: return traverseproto(g, gco2p(o));
662 : 3930 : case LUA_VTHREAD: return traversethread(g, gco2th(o));
663 : 0 : default: lua_assert(0); return 0;
664 : : }
665 : 30411 : }
666 : :
667 : :
668 : 7860 : static lu_mem propagateall (global_State *g) {
669 : 7860 : lu_mem tot = 0;
670 [ + + ]: 9834 : while (g->gray)
671 : 1974 : tot += propagatemark(g);
672 : 7860 : 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 : : */
683 : 3930 : static void convergeephemerons (global_State *g) {
684 : : int changed;
685 : 3930 : int dir = 0;
686 : 3930 : do {
687 : : GCObject *w;
688 : 3930 : GCObject *next = g->ephemeron; /* get ephemeron list */
689 : 3930 : g->ephemeron = NULL; /* tables may return to this list when traversed */
690 : 3930 : changed = 0;
691 [ - + ]: 3930 : while ((w = next) != NULL) { /* for each ephemeron table */
692 : 0 : Table *h = gco2t(w);
693 : 0 : next = h->gclist; /* list is rebuilt during loop */
694 : 0 : nw2black(h); /* out of the list (for now) */
695 [ # # ]: 0 : if (traverseephemeron(g, h, dir)) { /* marked some value? */
696 : 0 : propagateall(g); /* propagate changes */
697 : 0 : changed = 1; /* will have to revisit all ephemeron tables */
698 : 0 : }
699 : : }
700 : 3930 : dir = !dir; /* invert direction next time */
701 [ - + ]: 3930 : } while (changed); /* repeat until no more changes */
702 : 3930 : }
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 : 3930 : static void clearbykeys (global_State *g, GCObject *l) {
718 [ - + ]: 3930 : for (; l; l = gco2t(l)->gclist) {
719 : 0 : Table *h = gco2t(l);
720 : 0 : Node *limit = gnodelast(h);
721 : : Node *n;
722 [ # # ]: 0 : for (n = gnode(h, 0); n < limit; n++) {
723 [ # # # # ]: 0 : if (iscleared(g, gckeyN(n))) /* unmarked key? */
724 : 0 : setempty(gval(n)); /* remove entry */
725 [ # # ]: 0 : if (isempty(gval(n))) /* is entry empty? */
726 : 0 : clearkey(n); /* clear its key */
727 : 0 : }
728 : 0 : }
729 : 3930 : }
730 : :
731 : :
732 : : /*
733 : : ** clear entries with unmarked values from all weaktables in list 'l' up
734 : : ** to element 'f'
735 : : */
736 : 7860 : static void clearbyvalues (global_State *g, GCObject *l, GCObject *f) {
737 [ - + ]: 7860 : for (; l != f; l = gco2t(l)->gclist) {
738 : 0 : Table *h = gco2t(l);
739 : 0 : Node *n, *limit = gnodelast(h);
740 : : unsigned int i;
741 : 0 : unsigned int asize = luaH_realasize(h);
742 [ # # ]: 0 : for (i = 0; i < asize; i++) {
743 : 0 : TValue *o = &h->array[i];
744 [ # # # # ]: 0 : if (iscleared(g, gcvalueN(o))) /* value was collected? */
745 : 0 : setempty(o); /* remove entry */
746 : 0 : }
747 [ # # ]: 0 : for (n = gnode(h, 0); n < limit; n++) {
748 [ # # # # ]: 0 : if (iscleared(g, gcvalueN(gval(n)))) /* unmarked value? */
749 : 0 : setempty(gval(n)); /* remove entry */
750 [ # # ]: 0 : if (isempty(gval(n))) /* is entry empty? */
751 : 0 : clearkey(n); /* clear its key */
752 : 0 : }
753 : 0 : }
754 : 7860 : }
755 : :
756 : :
757 : 40 : static void freeupval (lua_State *L, UpVal *uv) {
758 [ - + ]: 40 : if (upisopen(uv))
759 : 0 : luaF_unlinkupval(uv);
760 : 40 : luaM_free(L, uv);
761 : 40 : }
762 : :
763 : :
764 : 14066 : static void freeobj (lua_State *L, GCObject *o) {
765 [ + - + + : 14066 : switch (o->tt) {
+ + - + +
+ ]
766 : : case LUA_VPROTO:
767 : 40 : luaF_freeproto(L, gco2p(o));
768 : 40 : break;
769 : : case LUA_VUPVAL:
770 : 40 : freeupval(L, gco2upv(o));
771 : 40 : break;
772 : : case LUA_VLCL: {
773 : 40 : LClosure *cl = gco2lcl(o);
774 : 40 : luaM_freemem(L, cl, sizeLclosure(cl->nupvalues));
775 : 40 : break;
776 : : }
777 : : case LUA_VCCL: {
778 : 280 : CClosure *cl = gco2ccl(o);
779 : 280 : luaM_freemem(L, cl, sizeCclosure(cl->nupvalues));
780 : 280 : break;
781 : : }
782 : : case LUA_VTABLE:
783 : 1045 : luaH_free(L, gco2t(o));
784 : 1045 : break;
785 : : case LUA_VTHREAD:
786 : 0 : luaE_freethread(L, gco2th(o));
787 : 0 : break;
788 : : case LUA_VUSERDATA: {
789 : 160 : Udata *u = gco2u(o);
790 [ + - ]: 160 : luaM_freemem(L, o, sizeudata(u->nuvalue, u->len));
791 : 160 : break;
792 : : }
793 : : case LUA_VSHRSTR: {
794 : 12225 : TString *ts = gco2ts(o);
795 : 12225 : luaS_remove(L, ts); /* remove it from hash table */
796 : 12225 : luaM_freemem(L, ts, sizelstring(ts->shrlen));
797 : 12225 : break;
798 : : }
799 : : case LUA_VLNGSTR: {
800 : 236 : TString *ts = gco2ts(o);
801 : 236 : luaM_freemem(L, ts, sizelstring(ts->u.lnglen));
802 : 236 : break;
803 : : }
804 : : default: lua_assert(0);
805 : 0 : }
806 : 14066 : }
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 : 8205 : static GCObject **sweeplist (lua_State *L, GCObject **p, int countin,
817 : : int *countout) {
818 : 8205 : global_State *g = G(L);
819 : 8205 : int ow = otherwhite(g);
820 : : int i;
821 : 8205 : int white = luaC_white(g); /* current white */
822 [ + + + + ]: 153475 : for (i = 0; *p != NULL && i < countin; i++) {
823 : 145270 : GCObject *curr = *p;
824 : 145270 : int marked = curr->marked;
825 [ + + ]: 145270 : if (isdeadm(ow, marked)) { /* is 'curr' dead? */
826 : 3946 : *p = curr->next; /* remove 'curr' from list */
827 : 3946 : freeobj(L, curr); /* erase 'curr' */
828 : 3946 : }
829 : : else { /* change mark to 'white' */
830 : 141324 : curr->marked = cast_byte((marked & ~maskgcbits) | white);
831 : 141324 : p = &curr->next; /* go to next element */
832 : : }
833 : 145270 : }
834 [ + + ]: 8205 : if (countout)
835 : 6240 : *countout = i; /* number of elements traversed */
836 [ + + ]: 8205 : return (*p == NULL) ? NULL : p;
837 : : }
838 : :
839 : :
840 : : /*
841 : : ** sweep a list until a live object (or end of list)
842 : : */
843 : 1965 : static GCObject **sweeptolive (lua_State *L, GCObject **p) {
844 : 1965 : GCObject **old = p;
845 : 1965 : do {
846 : 1965 : p = sweeplist(L, p, 1, NULL);
847 [ - + ]: 1965 : } while (p == old);
848 : 1965 : return p;
849 : : }
850 : :
851 : : /* }====================================================== */
852 : :
853 : :
854 : : /*
855 : : ** {======================================================
856 : : ** Finalization
857 : : ** =======================================================
858 : : */
859 : :
860 : : /*
861 : : ** If possible, shrink string table.
862 : : */
863 : 1965 : static void checkSizes (lua_State *L, global_State *g) {
864 [ + - ]: 1965 : if (!g->gcemergency) {
865 [ + - ]: 1965 : if (g->strt.nuse < g->strt.size / 4) { /* string table too big? */
866 : 0 : l_mem olddebt = g->GCdebt;
867 : 0 : luaS_resize(L, g->strt.size / 2);
868 : 0 : g->GCestimate += g->GCdebt - olddebt; /* correct estimate */
869 : 0 : }
870 : 1965 : }
871 : 1965 : }
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 : : */
878 : 169 : static GCObject *udata2finalize (global_State *g) {
879 : 169 : GCObject *o = g->tobefnz; /* get first element */
880 : : lua_assert(tofinalize(o));
881 : 169 : g->tobefnz = o->next; /* remove it from 'tobefnz' list */
882 : 169 : o->next = g->allgc; /* return it to 'allgc' list */
883 : 169 : g->allgc = o;
884 : 169 : resetbit(o->marked, FINALIZEDBIT); /* object is "normal" again */
885 [ + - - + ]: 169 : if (issweepphase(g))
886 : 0 : makewhite(g, o); /* "sweep" object */
887 [ + - ]: 169 : else if (getage(o) == G_OLD1)
888 : 0 : g->firstold1 = o; /* it is the first OLD1 object in the list */
889 : 169 : return o;
890 : : }
891 : :
892 : :
893 : 169 : static void dothecall (lua_State *L, void *ud) {
894 : 169 : UNUSED(ud);
895 : 169 : luaD_callnoyield(L, L->top - 2, 0);
896 : 169 : }
897 : :
898 : :
899 : 169 : static void GCTM (lua_State *L) {
900 : 169 : global_State *g = G(L);
901 : : const TValue *tm;
902 : : TValue v;
903 : : lua_assert(!g->gcemergency);
904 : 169 : setgcovalue(L, &v, udata2finalize(g));
905 : 169 : tm = luaT_gettmbyobj(L, &v, TM_GC);
906 [ - + ]: 169 : if (!notm(tm)) { /* is there a finalizer? */
907 : : int status;
908 : 169 : lu_byte oldah = L->allowhook;
909 : 169 : int running = g->gcrunning;
910 : 169 : L->allowhook = 0; /* stop debug hooks during GC metamethod */
911 : 169 : g->gcrunning = 0; /* avoid GC steps */
912 : 169 : setobj2s(L, L->top++, tm); /* push finalizer... */
913 : 169 : setobj2s(L, L->top++, &v); /* ... and its argument */
914 : 169 : L->ci->callstatus |= CIST_FIN; /* will run a finalizer */
915 : 169 : status = luaD_pcall(L, dothecall, NULL, savestack(L, L->top - 2), 0);
916 : 169 : L->ci->callstatus &= ~CIST_FIN; /* not running a finalizer anymore */
917 : 169 : L->allowhook = oldah; /* restore hooks */
918 : 169 : g->gcrunning = running; /* restore state */
919 [ - + ]: 169 : if (unlikely(status != LUA_OK)) { /* error while running __gc? */
920 : 0 : luaE_warnerror(L, "__gc metamethod");
921 : 0 : L->top--; /* pops error object */
922 : 0 : }
923 : 169 : }
924 : 169 : }
925 : :
926 : :
927 : : /*
928 : : ** Call a few finalizers
929 : : */
930 : 9 : static int runafewfinalizers (lua_State *L, int n) {
931 : 9 : global_State *g = G(L);
932 : : int i;
933 [ - + + + ]: 18 : for (i = 0; i < n && g->tobefnz; i++)
934 : 9 : GCTM(L); /* call one finalizer */
935 : 9 : return i;
936 : : }
937 : :
938 : :
939 : : /*
940 : : ** call all pending finalizers
941 : : */
942 : 40 : static void callallpendingfinalizers (lua_State *L) {
943 : 40 : global_State *g = G(L);
944 [ + + ]: 200 : while (g->tobefnz)
945 : 160 : GCTM(L);
946 : 40 : }
947 : :
948 : :
949 : : /*
950 : : ** find last 'next' field in list 'p' list (to add elements in its end)
951 : : */
952 : 2005 : static GCObject **findlast (GCObject **p) {
953 [ - + ]: 2005 : while (*p != NULL)
954 : 0 : p = &(*p)->next;
955 : 2005 : 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 : 2005 : static void separatetobefnz (global_State *g, int all) {
967 : : GCObject *curr;
968 : 2005 : GCObject **p = &g->finobj;
969 : 2005 : GCObject **lastnext = findlast(&g->tobefnz);
970 [ + + ]: 4364 : while ((curr = *p) != g->finobjold1) { /* traverse all finalizable objects */
971 : : lua_assert(tofinalize(curr));
972 [ + + - + ]: 2359 : if (!(iswhite(curr) || all)) /* not being collected? */
973 : 2190 : p = &curr->next; /* don't bother with it */
974 : : else {
975 [ + - ]: 169 : if (curr == g->finobjsur) /* removing 'finobjsur'? */
976 : 0 : g->finobjsur = curr->next; /* correct it */
977 : 169 : *p = curr->next; /* remove 'curr' from 'finobj' list */
978 : 169 : curr->next = *lastnext; /* link at the end of 'tobefnz' list */
979 : 169 : *lastnext = curr;
980 : 169 : lastnext = &curr->next;
981 : : }
982 : : }
983 : 2005 : }
984 : :
985 : :
986 : : /*
987 : : ** If pointer 'p' points to 'o', move it to the next element.
988 : : */
989 : 13036 : static void checkpointer (GCObject **p, GCObject *o) {
990 [ - + ]: 13036 : if (o == *p)
991 : 0 : *p = o->next;
992 : 13036 : }
993 : :
994 : :
995 : : /*
996 : : ** Correct pointers to objects inside 'allgc' list when
997 : : ** object 'o' is being removed from the list.
998 : : */
999 : 3259 : static void correctpointers (global_State *g, GCObject *o) {
1000 : 3259 : checkpointer(&g->survival, o);
1001 : 3259 : checkpointer(&g->old1, o);
1002 : 3259 : checkpointer(&g->reallyold, o);
1003 : 3259 : checkpointer(&g->firstold1, o);
1004 : 3259 : }
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 : : */
1011 : 3259 : void luaC_checkfinalizer (lua_State *L, GCObject *o, Table *mt) {
1012 : 3259 : global_State *g = G(L);
1013 [ - + - + ]: 6518 : if (tofinalize(o) || /* obj. is already marked... */
1014 [ + - - + ]: 3259 : gfasttm(g, mt, TM_GC) == NULL) /* or has no finalizer? */
1015 : 0 : return; /* nothing to be done */
1016 : : else { /* move 'o' to 'finobj' list */
1017 : : GCObject **p;
1018 [ + - + - ]: 3259 : if (issweepphase(g)) {
1019 : 0 : makewhite(g, o); /* "sweep" object 'o' */
1020 [ # # ]: 0 : if (g->sweepgc == &o->next) /* should not remove 'sweepgc' object */
1021 : 0 : g->sweepgc = sweeptolive(L, g->sweepgc); /* change 'sweepgc' */
1022 : 0 : }
1023 : : else
1024 : 3259 : correctpointers(g, o);
1025 : : /* search for pointer pointing to 'o' */
1026 [ + + ]: 4069 : for (p = &g->allgc; *p != o; p = &(*p)->next) { /* empty */ }
1027 : 3259 : *p = o->next; /* remove 'o' from 'allgc' list */
1028 : 3259 : o->next = g->finobj; /* link it in 'finobj' list */
1029 : 3259 : g->finobj = o;
1030 : 3259 : l_setbit(o->marked, FINALIZEDBIT); /* mark it as such */
1031 : : }
1032 : 3259 : }
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 : 0 : static void sweep2old (lua_State *L, GCObject **p) {
1053 : : GCObject *curr;
1054 : 0 : global_State *g = G(L);
1055 [ # # ]: 0 : while ((curr = *p) != NULL) {
1056 [ # # ]: 0 : if (iswhite(curr)) { /* is 'curr' dead? */
1057 : : lua_assert(isdead(g, curr));
1058 : 0 : *p = curr->next; /* remove 'curr' from list */
1059 : 0 : freeobj(L, curr); /* erase 'curr' */
1060 : 0 : }
1061 : : else { /* all surviving objects become old */
1062 : 0 : setage(curr, G_OLD);
1063 [ # # ]: 0 : if (curr->tt == LUA_VTHREAD) { /* threads must be watched */
1064 : 0 : lua_State *th = gco2th(curr);
1065 : 0 : linkgclist(th, g->grayagain); /* insert into 'grayagain' list */
1066 : 0 : }
1067 [ # # # # ]: 0 : else if (curr->tt == LUA_VUPVAL && upisopen(gco2upv(curr)))
1068 : 0 : set2gray(curr); /* open upvalues are always gray */
1069 : : else /* everything else is black */
1070 : 0 : nw2black(curr);
1071 : 0 : p = &curr->next; /* go to next element */
1072 : : }
1073 : : }
1074 : 0 : }
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 : : */
1088 : 0 : static GCObject **sweepgen (lua_State *L, global_State *g, GCObject **p,
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 : 0 : int white = luaC_white(g);
1100 : : GCObject *curr;
1101 [ # # ]: 0 : while ((curr = *p) != limit) {
1102 [ # # ]: 0 : if (iswhite(curr)) { /* is 'curr' dead? */
1103 : : lua_assert(!isold(curr) && isdead(g, curr));
1104 : 0 : *p = curr->next; /* remove 'curr' from list */
1105 : 0 : freeobj(L, curr); /* erase 'curr' */
1106 : 0 : }
1107 : : else { /* correct mark and age */
1108 [ # # ]: 0 : if (getage(curr) == G_NEW) { /* new objects go back to white */
1109 : 0 : int marked = curr->marked & ~maskgcbits; /* erase GC bits */
1110 : 0 : curr->marked = cast_byte(marked | G_SURVIVAL | white);
1111 : 0 : }
1112 : : else { /* all other objects will be old, and so keep their color */
1113 : 0 : setage(curr, nextage[getage(curr)]);
1114 [ # # # # ]: 0 : if (getage(curr) == G_OLD1 && *pfirstold1 == NULL)
1115 : 0 : *pfirstold1 = curr; /* first OLD1 object in the list */
1116 : : }
1117 : 0 : p = &curr->next; /* go to next element */
1118 : : }
1119 : : }
1120 : 0 : 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 : 0 : static void whitelist (global_State *g, GCObject *p) {
1130 : 0 : int white = luaC_white(g);
1131 [ # # ]: 0 : for (; p != NULL; p = p->next)
1132 : 0 : p->marked = cast_byte((p->marked & ~maskgcbits) | white);
1133 : 0 : }
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 : : */
1145 : 0 : static GCObject **correctgraylist (GCObject **p) {
1146 : : GCObject *curr;
1147 [ # # ]: 0 : while ((curr = *p) != NULL) {
1148 : 0 : GCObject **next = getgclist(curr);
1149 [ # # ]: 0 : if (iswhite(curr))
1150 : 0 : goto remove; /* remove all white objects */
1151 [ # # ]: 0 : else if (getage(curr) == G_TOUCHED1) { /* touched in this cycle? */
1152 : : lua_assert(isgray(curr));
1153 : 0 : nw2black(curr); /* make it black, for next barrier */
1154 : 0 : changeage(curr, G_TOUCHED1, G_TOUCHED2);
1155 : 0 : goto remain; /* keep it in the list and go to next element */
1156 : : }
1157 [ # # ]: 0 : else if (curr->tt == LUA_VTHREAD) {
1158 : : lua_assert(isgray(curr));
1159 : 0 : 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 [ # # ]: 0 : if (getage(curr) == G_TOUCHED2) /* advance from TOUCHED2... */
1164 : 0 : changeage(curr, G_TOUCHED2, G_OLD); /* ... to OLD */
1165 : 0 : nw2black(curr); /* make object black (to be removed) */
1166 : 0 : goto remove;
1167 : : }
1168 : 0 : remove: *p = *next; continue;
1169 : 0 : remain: p = next; continue;
1170 : : }
1171 : 0 : return p;
1172 : : }
1173 : :
1174 : :
1175 : : /*
1176 : : ** Correct all gray lists, coalescing them into 'grayagain'.
1177 : : */
1178 : 0 : static void correctgraylists (global_State *g) {
1179 : 0 : GCObject **list = correctgraylist(&g->grayagain);
1180 : 0 : *list = g->weak; g->weak = NULL;
1181 : 0 : list = correctgraylist(list);
1182 : 0 : *list = g->allweak; g->allweak = NULL;
1183 : 0 : list = correctgraylist(list);
1184 : 0 : *list = g->ephemeron; g->ephemeron = NULL;
1185 : 0 : correctgraylist(list);
1186 : 0 : }
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 : 0 : static void markold (global_State *g, GCObject *from, GCObject *to) {
1195 : : GCObject *p;
1196 [ # # ]: 0 : for (p = from; p != to; p = p->next) {
1197 [ # # ]: 0 : if (getage(p) == G_OLD1) {
1198 : : lua_assert(!iswhite(p));
1199 : 0 : changeage(p, G_OLD1, G_OLD); /* now they are old */
1200 [ # # ]: 0 : if (isblack(p))
1201 : 0 : reallymarkobject(g, p);
1202 : 0 : }
1203 : 0 : }
1204 : 0 : }
1205 : :
1206 : :
1207 : : /*
1208 : : ** Finish a young-generation collection.
1209 : : */
1210 : 0 : static void finishgencycle (lua_State *L, global_State *g) {
1211 : 0 : correctgraylists(g);
1212 : 0 : checkSizes(L, g);
1213 : 0 : g->gcstate = GCSpropagate; /* skip restart */
1214 [ # # ]: 0 : if (!g->gcemergency)
1215 : 0 : callallpendingfinalizers(L);
1216 : 0 : }
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 : : */
1224 : 0 : static void youngcollection (lua_State *L, global_State *g) {
1225 : : GCObject **psurvival; /* to point to first non-dead survival object */
1226 : : GCObject *dummy; /* dummy out parameter to 'sweepgen' */
1227 : : lua_assert(g->gcstate == GCSpropagate);
1228 [ # # ]: 0 : if (g->firstold1) { /* are there regular OLD1 objects? */
1229 : 0 : markold(g, g->firstold1, g->reallyold); /* mark them */
1230 : 0 : g->firstold1 = NULL; /* no more OLD1 objects (for now) */
1231 : 0 : }
1232 : 0 : markold(g, g->finobj, g->finobjrold);
1233 : 0 : markold(g, g->tobefnz, NULL);
1234 : 0 : atomic(L);
1235 : :
1236 : : /* sweep nursery and get a pointer to its last live element */
1237 : 0 : g->gcstate = GCSswpallgc;
1238 : 0 : psurvival = sweepgen(L, g, &g->allgc, g->survival, &g->firstold1);
1239 : : /* sweep 'survival' */
1240 : 0 : sweepgen(L, g, psurvival, g->old1, &g->firstold1);
1241 : 0 : g->reallyold = g->old1;
1242 : 0 : g->old1 = *psurvival; /* 'survival' survivals are old now */
1243 : 0 : g->survival = g->allgc; /* all news are survivals */
1244 : :
1245 : : /* repeat for 'finobj' lists */
1246 : 0 : dummy = NULL; /* no 'firstold1' optimization for 'finobj' lists */
1247 : 0 : psurvival = sweepgen(L, g, &g->finobj, g->finobjsur, &dummy);
1248 : : /* sweep 'survival' */
1249 : 0 : sweepgen(L, g, psurvival, g->finobjold1, &dummy);
1250 : 0 : g->finobjrold = g->finobjold1;
1251 : 0 : g->finobjold1 = *psurvival; /* 'survival' survivals are old now */
1252 : 0 : g->finobjsur = g->finobj; /* all news are survivals */
1253 : :
1254 : 0 : sweepgen(L, g, &g->tobefnz, NULL, &dummy);
1255 : 0 : finishgencycle(L, g);
1256 : 0 : }
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 : 0 : static void atomic2gen (lua_State *L, global_State *g) {
1266 : 0 : cleargraylists(g);
1267 : : /* sweep all elements making them old */
1268 : 0 : g->gcstate = GCSswpallgc;
1269 : 0 : sweep2old(L, &g->allgc);
1270 : : /* everything alive now is old */
1271 : 0 : g->reallyold = g->old1 = g->survival = g->allgc;
1272 : 0 : g->firstold1 = NULL; /* there are no OLD1 objects anywhere */
1273 : :
1274 : : /* repeat for 'finobj' lists */
1275 : 0 : sweep2old(L, &g->finobj);
1276 : 0 : g->finobjrold = g->finobjold1 = g->finobjsur = g->finobj;
1277 : :
1278 : 0 : sweep2old(L, &g->tobefnz);
1279 : :
1280 : 0 : g->gckind = KGC_GEN;
1281 : 0 : g->lastatomic = 0;
1282 : 0 : g->GCestimate = gettotalbytes(g); /* base for memory control */
1283 : 0 : finishgencycle(L, g);
1284 : 0 : }
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 : : */
1293 : 0 : static lu_mem entergen (lua_State *L, global_State *g) {
1294 : : lu_mem numobjs;
1295 : 0 : luaC_runtilstate(L, bitmask(GCSpause)); /* prepare to start a new cycle */
1296 : 0 : luaC_runtilstate(L, bitmask(GCSpropagate)); /* start new cycle */
1297 : 0 : numobjs = atomic(L); /* propagates all and then do the atomic stuff */
1298 : 0 : atomic2gen(L, g);
1299 : 0 : 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 : 0 : static void enterinc (global_State *g) {
1309 : 0 : whitelist(g, g->allgc);
1310 : 0 : g->reallyold = g->old1 = g->survival = NULL;
1311 : 0 : whitelist(g, g->finobj);
1312 : 0 : whitelist(g, g->tobefnz);
1313 : 0 : g->finobjrold = g->finobjold1 = g->finobjsur = NULL;
1314 : 0 : g->gcstate = GCSpause;
1315 : 0 : g->gckind = KGC_INC;
1316 : 0 : g->lastatomic = 0;
1317 : 0 : }
1318 : :
1319 : :
1320 : : /*
1321 : : ** Change collector mode to 'newmode'.
1322 : : */
1323 : 40 : void luaC_changemode (lua_State *L, int newmode) {
1324 : 40 : global_State *g = G(L);
1325 [ + - ]: 40 : if (newmode != g->gckind) {
1326 [ # # ]: 0 : if (newmode == KGC_GEN) /* entering generational mode? */
1327 : 0 : entergen(L, g);
1328 : : else
1329 : 0 : enterinc(g); /* entering incremental mode */
1330 : 0 : }
1331 : 40 : g->lastatomic = 0;
1332 : 40 : }
1333 : :
1334 : :
1335 : : /*
1336 : : ** Does a full collection in generational mode.
1337 : : */
1338 : 0 : static lu_mem fullgen (lua_State *L, global_State *g) {
1339 : 0 : enterinc(g);
1340 : 0 : 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 : 0 : static void setminordebt (global_State *g) {
1349 : 0 : luaE_setdebt(g, -(cast(l_mem, (gettotalbytes(g) / 100)) * g->genminormul));
1350 : 0 : }
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 : 0 : static void stepgenfull (lua_State *L, global_State *g) {
1375 : : lu_mem newatomic; /* count of traversed objects */
1376 : 0 : lu_mem lastatomic = g->lastatomic; /* count from last collection */
1377 [ # # ]: 0 : if (g->gckind == KGC_GEN) /* still in generational mode? */
1378 : 0 : enterinc(g); /* enter incremental mode */
1379 : 0 : luaC_runtilstate(L, bitmask(GCSpropagate)); /* start new cycle */
1380 : 0 : newatomic = atomic(L); /* mark everybody */
1381 [ # # ]: 0 : if (newatomic < lastatomic + (lastatomic >> 3)) { /* good collection? */
1382 : 0 : atomic2gen(L, g); /* return to generational mode */
1383 : 0 : setminordebt(g);
1384 : 0 : }
1385 : : else { /* another bad collection; stay in incremental mode */
1386 : 0 : g->GCestimate = gettotalbytes(g); /* first estimate */;
1387 : 0 : entersweep(L);
1388 : 0 : luaC_runtilstate(L, bitmask(GCSpause)); /* finish collection */
1389 : 0 : setpause(g);
1390 : 0 : g->lastatomic = newatomic;
1391 : : }
1392 : 0 : }
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 : 0 : static void genstep (lua_State *L, global_State *g) {
1415 [ # # ]: 0 : if (g->lastatomic != 0) /* last collection was a bad one? */
1416 : 0 : stepgenfull(L, g); /* do a full step */
1417 : : else {
1418 : 0 : lu_mem majorbase = g->GCestimate; /* memory after last major collection */
1419 : 0 : lu_mem majorinc = (majorbase / 100) * getgcparam(g->genmajormul);
1420 [ # # # # ]: 0 : if (g->GCdebt > 0 && gettotalbytes(g) > majorbase + majorinc) {
1421 : 0 : lu_mem numobjs = fullgen(L, g); /* do a major collection */
1422 [ # # ]: 0 : if (gettotalbytes(g) < majorbase + (majorinc / 2)) {
1423 : : /* collected at least half of memory growth since last major
1424 : : collection; keep doing minor collections */
1425 : 0 : setminordebt(g);
1426 : 0 : }
1427 : : else { /* bad collection */
1428 : 0 : g->lastatomic = numobjs; /* signal that last collection was bad */
1429 : 0 : setpause(g); /* do a long wait for next (major) collection */
1430 : : }
1431 : 0 : }
1432 : : else { /* regular case; do a minor collection */
1433 : 0 : youngcollection(L, g);
1434 : 0 : setminordebt(g);
1435 : 0 : g->GCestimate = majorbase; /* preserve base value */
1436 : : }
1437 : : }
1438 : : lua_assert(isdecGCmodegen(g));
1439 : 0 : }
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 : 1965 : static void setpause (global_State *g) {
1458 : : l_mem threshold, debt;
1459 : 1965 : int pause = getgcparam(g->gcpause);
1460 : 1965 : l_mem estimate = g->GCestimate / PAUSEADJ; /* adjust 'estimate' */
1461 : : lua_assert(estimate > 0);
1462 [ + - ]: 1965 : threshold = (pause < MAX_LMEM / estimate) /* overflow? */
1463 : 1965 : ? estimate * pause /* no overflow */
1464 : : : MAX_LMEM; /* overflow; truncate to maximum */
1465 : 1965 : debt = gettotalbytes(g) - threshold;
1466 [ + - ]: 1965 : if (debt > 0) debt = 0;
1467 : 1965 : luaE_setdebt(g, debt);
1468 : 1965 : }
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 : 1965 : static void entersweep (lua_State *L) {
1479 : 1965 : global_State *g = G(L);
1480 : 1965 : g->gcstate = GCSswpallgc;
1481 : : lua_assert(g->sweepgc == NULL);
1482 : 1965 : g->sweepgc = sweeptolive(L, &g->allgc);
1483 : 1965 : }
1484 : :
1485 : :
1486 : : /*
1487 : : ** Delete all objects in list 'p' until (but not including) object
1488 : : ** 'limit'.
1489 : : */
1490 : 120 : static void deletelist (lua_State *L, GCObject *p, GCObject *limit) {
1491 [ + + ]: 10240 : while (p != limit) {
1492 : 10120 : GCObject *next = p->next;
1493 : 10120 : freeobj(L, p);
1494 : 10120 : p = next;
1495 : : }
1496 : 120 : }
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 : : */
1503 : 40 : void luaC_freeallobjects (lua_State *L) {
1504 : 40 : global_State *g = G(L);
1505 : 40 : luaC_changemode(L, KGC_INC);
1506 : 40 : separatetobefnz(g, 1); /* separate all objects with finalizers */
1507 : : lua_assert(g->finobj == NULL);
1508 : 40 : callallpendingfinalizers(L);
1509 : 40 : deletelist(L, g->allgc, obj2gco(g->mainthread));
1510 : 40 : deletelist(L, g->finobj, NULL);
1511 : 40 : deletelist(L, g->fixedgc, NULL); /* collect fixed objects */
1512 : : lua_assert(g->strt.nuse == 0);
1513 : 40 : }
1514 : :
1515 : :
1516 : 1965 : static lu_mem atomic (lua_State *L) {
1517 : 1965 : global_State *g = G(L);
1518 : 1965 : lu_mem work = 0;
1519 : : GCObject *origweak, *origall;
1520 : 1965 : GCObject *grayagain = g->grayagain; /* save original list */
1521 : 1965 : g->grayagain = NULL;
1522 : : lua_assert(g->ephemeron == NULL && g->weak == NULL);
1523 : : lua_assert(!iswhite(g->mainthread));
1524 : 1965 : g->gcstate = GCSatomic;
1525 [ - + ]: 1965 : markobject(g, L); /* mark running thread */
1526 : : /* registry and global metatables may be changed by API */
1527 [ + - - + ]: 1965 : markvalue(g, &g->l_registry);
1528 : 1965 : markmt(g); /* mark global metatables */
1529 : 1965 : work += propagateall(g); /* empties 'gray' list */
1530 : : /* remark occasional upvalues of (maybe) dead threads */
1531 : 1965 : work += remarkupvals(g);
1532 : 1965 : work += propagateall(g); /* propagate changes */
1533 : 1965 : g->gray = grayagain;
1534 : 1965 : work += propagateall(g); /* traverse 'grayagain' list */
1535 : 1965 : convergeephemerons(g);
1536 : : /* at this point, all strongly accessible objects are marked. */
1537 : : /* Clear values from weak tables, before checking finalizers */
1538 : 1965 : clearbyvalues(g, g->weak, NULL);
1539 : 1965 : clearbyvalues(g, g->allweak, NULL);
1540 : 1965 : origweak = g->weak; origall = g->allweak;
1541 : 1965 : separatetobefnz(g, 0); /* separate objects to be finalized */
1542 : 1965 : work += markbeingfnz(g); /* mark objects that will be finalized */
1543 : 1965 : work += propagateall(g); /* remark, to propagate 'resurrection' */
1544 : 1965 : convergeephemerons(g);
1545 : : /* at this point, all resurrected objects are marked. */
1546 : : /* remove dead objects from weak tables */
1547 : 1965 : clearbykeys(g, g->ephemeron); /* clear keys from all ephemeron tables */
1548 : 1965 : clearbykeys(g, g->allweak); /* clear keys from all 'allweak' tables */
1549 : : /* clear values from resurrected weak tables */
1550 : 1965 : clearbyvalues(g, g->weak, origweak);
1551 : 1965 : clearbyvalues(g, g->allweak, origall);
1552 : 1965 : luaS_clearcache(g);
1553 : 1965 : g->currentwhite = cast_byte(otherwhite(g)); /* flip current white */
1554 : : lua_assert(g->gray == NULL);
1555 : 1965 : return work; /* estimate of slots marked by 'atomic' */
1556 : : }
1557 : :
1558 : :
1559 : 12135 : static int sweepstep (lua_State *L, global_State *g,
1560 : : int nextstate, GCObject **nextlist) {
1561 [ + + ]: 12135 : if (g->sweepgc) {
1562 : 6240 : l_mem olddebt = g->GCdebt;
1563 : : int count;
1564 : 6240 : g->sweepgc = sweeplist(L, g->sweepgc, GCSWEEPMAX, &count);
1565 : 6240 : g->GCestimate += g->GCdebt - olddebt; /* update estimate */
1566 : 6240 : return count;
1567 : : }
1568 : : else { /* enter next state */
1569 : 5895 : g->gcstate = nextstate;
1570 : 5895 : g->sweepgc = nextlist;
1571 : 5895 : return 0; /* no work done */
1572 : : }
1573 : 12135 : }
1574 : :
1575 : :
1576 : 50406 : static lu_mem singlestep (lua_State *L) {
1577 : 50406 : global_State *g = G(L);
1578 [ + - + + : 50406 : switch (g->gcstate) {
+ + + +
+ ]
1579 : : case GCSpause: {
1580 : 1965 : restartcollection(g);
1581 : 1965 : g->gcstate = GCSpropagate;
1582 : 1965 : return 1;
1583 : : }
1584 : : case GCSpropagate: {
1585 [ + + ]: 30402 : if (g->gray == NULL) { /* no more gray objects? */
1586 : 1965 : g->gcstate = GCSenteratomic; /* finish propagate phase */
1587 : 1965 : return 0;
1588 : : }
1589 : : else
1590 : 28437 : return propagatemark(g); /* traverse one gray object */
1591 : : }
1592 : : case GCSenteratomic: {
1593 : 1965 : lu_mem work = atomic(L); /* work is what was traversed by 'atomic' */
1594 : 1965 : entersweep(L);
1595 : 1965 : g->GCestimate = gettotalbytes(g); /* first estimate */;
1596 : 1965 : return work;
1597 : : }
1598 : : case GCSswpallgc: { /* sweep "regular" objects */
1599 : 4275 : return sweepstep(L, g, GCSswpfinobj, &g->finobj);
1600 : : }
1601 : : case GCSswpfinobj: { /* sweep objects with finalizers */
1602 : 3930 : return sweepstep(L, g, GCSswptobefnz, &g->tobefnz);
1603 : : }
1604 : : case GCSswptobefnz: { /* sweep objects to be finalized */
1605 : 3930 : return sweepstep(L, g, GCSswpend, NULL);
1606 : : }
1607 : : case GCSswpend: { /* finish sweeps */
1608 : 1965 : checkSizes(L, g);
1609 : 1965 : g->gcstate = GCScallfin;
1610 : 1965 : return 0;
1611 : : }
1612 : : case GCScallfin: { /* call remaining finalizers */
1613 [ + + + - ]: 1974 : if (g->tobefnz && !g->gcemergency) {
1614 : 9 : int n = runafewfinalizers(L, GCFINMAX);
1615 : 9 : return n * GCFINALIZECOST;
1616 : : }
1617 : : else { /* emergency mode or no more finalizers */
1618 : 1965 : g->gcstate = GCSpause; /* finish collection */
1619 : 1965 : return 0;
1620 : : }
1621 : : }
1622 : 0 : default: lua_assert(0); return 0;
1623 : : }
1624 : 50406 : }
1625 : :
1626 : :
1627 : : /*
1628 : : ** advances the garbage collector until it reaches a state allowed
1629 : : ** by 'statemask'
1630 : : */
1631 : 0 : void luaC_runtilstate (lua_State *L, int statesmask) {
1632 : 0 : global_State *g = G(L);
1633 [ # # ]: 0 : while (!testbit(statesmask, g->gcstate))
1634 : 0 : singlestep(L);
1635 : 0 : }
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 : 1965 : static void incstep (lua_State *L, global_State *g) {
1646 : 1965 : int stepmul = (getgcparam(g->gcstepmul) | 1); /* avoid division by 0 */
1647 : 1965 : l_mem debt = (g->GCdebt / WORK2MEM) * stepmul;
1648 [ + - ]: 1965 : l_mem stepsize = (g->gcstepsize <= log2maxs(l_mem))
1649 : 1965 : ? ((cast(l_mem, 1) << g->gcstepsize) / WORK2MEM) * stepmul
1650 : : : MAX_LMEM; /* overflow; keep maximum value */
1651 : 1965 : do { /* repeat until pause or enough "credit" (negative debt) */
1652 : 50406 : lu_mem work = singlestep(L); /* perform one single step */
1653 : 50406 : debt -= work;
1654 [ - + + + ]: 50406 : } while (debt > -stepsize && g->gcstate != GCSpause);
1655 [ + - ]: 1965 : if (g->gcstate == GCSpause)
1656 : 1965 : setpause(g); /* pause until next cycle */
1657 : : else {
1658 : 0 : debt = (debt / stepmul) * WORK2MEM; /* convert 'work units' to bytes */
1659 : 0 : luaE_setdebt(g, debt);
1660 : : }
1661 : 1965 : }
1662 : :
1663 : : /*
1664 : : ** performs a basic GC step if collector is running
1665 : : */
1666 : 1965 : void luaC_step (lua_State *L) {
1667 : 1965 : global_State *g = G(L);
1668 : : lua_assert(!g->gcemergency);
1669 [ - + ]: 1965 : if (g->gcrunning) { /* running? */
1670 [ + - + - ]: 1965 : if(isdecGCmodegen(g))
1671 : 0 : genstep(L, g);
1672 : : else
1673 : 1965 : incstep(L, g);
1674 : 1965 : }
1675 : 1965 : }
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 : 0 : static void fullinc (lua_State *L, global_State *g) {
1686 [ # # ]: 0 : if (keepinvariant(g)) /* black objects? */
1687 : 0 : entersweep(L); /* sweep everything to turn them back to white */
1688 : : /* finish any pending sweep phase to start a new cycle */
1689 : 0 : luaC_runtilstate(L, bitmask(GCSpause));
1690 : 0 : luaC_runtilstate(L, bitmask(GCScallfin)); /* run up to finalizers */
1691 : : /* estimate must be correct after a full GC cycle */
1692 : : lua_assert(g->GCestimate == gettotalbytes(g));
1693 : 0 : luaC_runtilstate(L, bitmask(GCSpause)); /* finish collection */
1694 : 0 : setpause(g);
1695 : 0 : }
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 : 0 : void luaC_fullgc (lua_State *L, int isemergency) {
1704 : 0 : global_State *g = G(L);
1705 : : lua_assert(!g->gcemergency);
1706 : 0 : g->gcemergency = isemergency; /* set flag */
1707 [ # # ]: 0 : if (g->gckind == KGC_INC)
1708 : 0 : fullinc(L, g);
1709 : : else
1710 : 0 : fullgen(L, g);
1711 : 0 : g->gcemergency = 0;
1712 : 0 : }
1713 : :
1714 : : /* }====================================================== */
1715 : :
1716 : :
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