diff options
Diffstat (limited to 'third_party/lua/src/lgc.c')
| -rw-r--r-- | third_party/lua/src/lgc.c | 1213 |
1 files changed, 0 insertions, 1213 deletions
diff --git a/third_party/lua/src/lgc.c b/third_party/lua/src/lgc.c deleted file mode 100644 index 535e988ae0..0000000000 --- a/third_party/lua/src/lgc.c +++ /dev/null @@ -1,1213 +0,0 @@ -/* -** $Id: lgc.c,v 2.140 2013/03/16 21:10:18 roberto Exp $ -** Garbage Collector -** See Copyright Notice in lua.h -*/ - -#include <string.h> - -#define lgc_c -#define LUA_CORE - -#include "lua.h" - -#include "ldebug.h" -#include "ldo.h" -#include "lfunc.h" -#include "lgc.h" -#include "lmem.h" -#include "lobject.h" -#include "lstate.h" -#include "lstring.h" -#include "ltable.h" -#include "ltm.h" - - - -/* -** cost of sweeping one element (the size of a small object divided -** by some adjust for the sweep speed) -*/ -#define GCSWEEPCOST ((sizeof(TString) + 4) / 4) - -/* maximum number of elements to sweep in each single step */ -#define GCSWEEPMAX (cast_int((GCSTEPSIZE / GCSWEEPCOST) / 4)) - -/* maximum number of finalizers to call in each GC step */ -#define GCFINALIZENUM 4 - - -/* -** macro to adjust 'stepmul': 'stepmul' is actually used like -** 'stepmul / STEPMULADJ' (value chosen by tests) -*/ -#define STEPMULADJ 200 - - -/* -** macro to adjust 'pause': 'pause' is actually used like -** 'pause / PAUSEADJ' (value chosen by tests) -*/ -#define PAUSEADJ 100 - - -/* -** 'makewhite' erases all color bits plus the old bit and then -** sets only the current white bit -*/ -#define maskcolors (~(bit2mask(BLACKBIT, OLDBIT) | WHITEBITS)) -#define makewhite(g,x) \ - (gch(x)->marked = cast_byte((gch(x)->marked & maskcolors) | luaC_white(g))) - -#define white2gray(x) resetbits(gch(x)->marked, WHITEBITS) -#define black2gray(x) resetbit(gch(x)->marked, BLACKBIT) - - -#define isfinalized(x) testbit(gch(x)->marked, FINALIZEDBIT) - -#define checkdeadkey(n) lua_assert(!ttisdeadkey(gkey(n)) || ttisnil(gval(n))) - - -#define checkconsistency(obj) \ - lua_longassert(!iscollectable(obj) || righttt(obj)) - - -#define markvalue(g,o) { checkconsistency(o); \ - if (valiswhite(o)) reallymarkobject(g,gcvalue(o)); } - -#define markobject(g,t) { if ((t) && iswhite(obj2gco(t))) \ - reallymarkobject(g, obj2gco(t)); } - -static void reallymarkobject (global_State *g, GCObject *o); - - -/* -** {====================================================== -** Generic functions -** ======================================================= -*/ - - -/* -** one after last element in a hash array -*/ -#define gnodelast(h) gnode(h, cast(size_t, sizenode(h))) - - -/* -** link table 'h' into list pointed by 'p' -*/ -#define linktable(h,p) ((h)->gclist = *(p), *(p) = obj2gco(h)) - - -/* -** if key is not marked, mark its entry as dead (therefore removing it -** from the table) -*/ -static void removeentry (Node *n) { - lua_assert(ttisnil(gval(n))); - if (valiswhite(gkey(n))) - setdeadvalue(gkey(n)); /* unused and unmarked key; remove it */ -} - - -/* -** tells whether a key or value can be cleared from a weak -** table. Non-collectable objects are never removed from weak -** tables. Strings behave as `values', so are never removed too. for -** other objects: if really collected, cannot keep them; for objects -** being finalized, keep them in keys, but not in values -*/ -static int iscleared (global_State *g, const TValue *o) { - if (!iscollectable(o)) return 0; - else if (ttisstring(o)) { - markobject(g, rawtsvalue(o)); /* strings are `values', so are never weak */ - return 0; - } - else return iswhite(gcvalue(o)); -} - - -/* -** barrier that moves collector forward, that is, mark the white object -** being pointed by a black object. -*/ -void luaC_barrier_ (lua_State *L, GCObject *o, GCObject *v) { - global_State *g = G(L); - lua_assert(isblack(o) && iswhite(v) && !isdead(g, v) && !isdead(g, o)); - lua_assert(g->gcstate != GCSpause); - lua_assert(gch(o)->tt != LUA_TTABLE); - if (keepinvariantout(g)) /* must keep invariant? */ - reallymarkobject(g, v); /* restore invariant */ - else { /* sweep phase */ - lua_assert(issweepphase(g)); - makewhite(g, o); /* mark main obj. as white to avoid other barriers */ - } -} - - -/* -** barrier that moves collector backward, that is, mark the black object -** pointing to a white object as gray again. (Current implementation -** only works for tables; access to 'gclist' is not uniform across -** different types.) -*/ -void luaC_barrierback_ (lua_State *L, GCObject *o) { - global_State *g = G(L); - lua_assert(isblack(o) && !isdead(g, o) && gch(o)->tt == LUA_TTABLE); - black2gray(o); /* make object gray (again) */ - gco2t(o)->gclist = g->grayagain; - g->grayagain = o; -} - - -/* -** barrier for prototypes. When creating first closure (cache is -** NULL), use a forward barrier; this may be the only closure of the -** prototype (if it is a "regular" function, with a single instance) -** and the prototype may be big, so it is better to avoid traversing -** it again. Otherwise, use a backward barrier, to avoid marking all -** possible instances. -*/ -LUAI_FUNC void luaC_barrierproto_ (lua_State *L, Proto *p, Closure *c) { - global_State *g = G(L); - lua_assert(isblack(obj2gco(p))); - if (p->cache == NULL) { /* first time? */ - luaC_objbarrier(L, p, c); - } - else { /* use a backward barrier */ - black2gray(obj2gco(p)); /* make prototype gray (again) */ - p->gclist = g->grayagain; - g->grayagain = obj2gco(p); - } -} - - -/* -** check color (and invariants) for an upvalue that was closed, -** i.e., moved into the 'allgc' list -*/ -void luaC_checkupvalcolor (global_State *g, UpVal *uv) { - GCObject *o = obj2gco(uv); - lua_assert(!isblack(o)); /* open upvalues are never black */ - if (isgray(o)) { - if (keepinvariant(g)) { - resetoldbit(o); /* see MOVE OLD rule */ - gray2black(o); /* it is being visited now */ - markvalue(g, uv->v); - } - else { - lua_assert(issweepphase(g)); - makewhite(g, o); - } - } -} - - -/* -** create a new collectable object (with given type and size) and link -** it to '*list'. 'offset' tells how many bytes to allocate before the -** object itself (used only by states). -*/ -GCObject *luaC_newobj (lua_State *L, int tt, size_t sz, GCObject **list, - int offset) { - global_State *g = G(L); - char *raw = cast(char *, luaM_newobject(L, novariant(tt), sz)); - GCObject *o = obj2gco(raw + offset); - if (list == NULL) - list = &g->allgc; /* standard list for collectable objects */ - gch(o)->marked = luaC_white(g); - gch(o)->tt = tt; - gch(o)->next = *list; - *list = o; - return o; -} - -/* }====================================================== */ - - - -/* -** {====================================================== -** Mark functions -** ======================================================= -*/ - - -/* -** mark an object. Userdata, strings, and closed upvalues are visited -** and turned black here. Other objects are marked gray and added -** to appropriate list to be visited (and turned black) later. (Open -** upvalues are already linked in 'headuv' list.) -*/ -static void reallymarkobject (global_State *g, GCObject *o) { - lu_mem size; - white2gray(o); - switch (gch(o)->tt) { - case LUA_TSHRSTR: - case LUA_TLNGSTR: { - size = sizestring(gco2ts(o)); - break; /* nothing else to mark; make it black */ - } - case LUA_TUSERDATA: { - Table *mt = gco2u(o)->metatable; - markobject(g, mt); - markobject(g, gco2u(o)->env); - size = sizeudata(gco2u(o)); - break; - } - case LUA_TUPVAL: { - UpVal *uv = gco2uv(o); - markvalue(g, uv->v); - if (uv->v != &uv->u.value) /* open? */ - return; /* open upvalues remain gray */ - size = sizeof(UpVal); - break; - } - case LUA_TLCL: { - gco2lcl(o)->gclist = g->gray; - g->gray = o; - return; - } - case LUA_TCCL: { - gco2ccl(o)->gclist = g->gray; - g->gray = o; - return; - } - case LUA_TTABLE: { - linktable(gco2t(o), &g->gray); - return; - } - case LUA_TTHREAD: { - gco2th(o)->gclist = g->gray; - g->gray = o; - return; - } - case LUA_TPROTO: { - gco2p(o)->gclist = g->gray; - g->gray = o; - return; - } - default: lua_assert(0); return; - } - gray2black(o); - g->GCmemtrav += size; -} - - -/* -** mark metamethods for basic types -*/ -static void markmt (global_State *g) { - int i; - for (i=0; i < LUA_NUMTAGS; i++) - markobject(g, g->mt[i]); -} - - -/* -** mark all objects in list of being-finalized -*/ -static void markbeingfnz (global_State *g) { - GCObject *o; - for (o = g->tobefnz; o != NULL; o = gch(o)->next) { - makewhite(g, o); - reallymarkobject(g, o); - } -} - - -/* -** mark all values stored in marked open upvalues. (See comment in -** 'lstate.h'.) -*/ -static void remarkupvals (global_State *g) { - UpVal *uv; - for (uv = g->uvhead.u.l.next; uv != &g->uvhead; uv = uv->u.l.next) { - if (isgray(obj2gco(uv))) - markvalue(g, uv->v); - } -} - - -/* -** mark root set and reset all gray lists, to start a new -** incremental (or full) collection -*/ -static void restartcollection (global_State *g) { - g->gray = g->grayagain = NULL; - g->weak = g->allweak = g->ephemeron = NULL; - markobject(g, g->mainthread); - markvalue(g, &g->l_registry); - markmt(g); - markbeingfnz(g); /* mark any finalizing object left from previous cycle */ -} - -/* }====================================================== */ - - -/* -** {====================================================== -** Traverse functions -** ======================================================= -*/ - -static void traverseweakvalue (global_State *g, Table *h) { - Node *n, *limit = gnodelast(h); - /* if there is array part, assume it may have white values (do not - traverse it just to check) */ - int hasclears = (h->sizearray > 0); - for (n = gnode(h, 0); n < limit; n++) { - checkdeadkey(n); - if (ttisnil(gval(n))) /* entry is empty? */ - removeentry(n); /* remove it */ - else { - lua_assert(!ttisnil(gkey(n))); - markvalue(g, gkey(n)); /* mark key */ - if (!hasclears && iscleared(g, gval(n))) /* is there a white value? */ - hasclears = 1; /* table will have to be cleared */ - } - } - if (hasclears) - linktable(h, &g->weak); /* has to be cleared later */ - else /* no white values */ - linktable(h, &g->grayagain); /* no need to clean */ -} - - -static int traverseephemeron (global_State *g, Table *h) { - int marked = 0; /* true if an object is marked in this traversal */ - int hasclears = 0; /* true if table has white keys */ - int prop = 0; /* true if table has entry "white-key -> white-value" */ - Node *n, *limit = gnodelast(h); - int i; - /* traverse array part (numeric keys are 'strong') */ - for (i = 0; i < h->sizearray; i++) { - if (valiswhite(&h->array[i])) { - marked = 1; - reallymarkobject(g, gcvalue(&h->array[i])); - } - } - /* traverse hash part */ - for (n = gnode(h, 0); n < limit; n++) { - checkdeadkey(n); - if (ttisnil(gval(n))) /* entry is empty? */ - removeentry(n); /* remove it */ - else if (iscleared(g, gkey(n))) { /* key is not marked (yet)? */ - hasclears = 1; /* table must be cleared */ - if (valiswhite(gval(n))) /* value not marked yet? */ - prop = 1; /* must propagate again */ - } - else if (valiswhite(gval(n))) { /* value not marked yet? */ - marked = 1; - reallymarkobject(g, gcvalue(gval(n))); /* mark it now */ - } - } - if (prop) - linktable(h, &g->ephemeron); /* have to propagate again */ - else if (hasclears) /* does table have white keys? */ - linktable(h, &g->allweak); /* may have to clean white keys */ - else /* no white keys */ - linktable(h, &g->grayagain); /* no need to clean */ - return marked; -} - - -static void traversestrongtable (global_State *g, Table *h) { - Node *n, *limit = gnodelast(h); - int i; - for (i = 0; i < h->sizearray; i++) /* traverse array part */ - markvalue(g, &h->array[i]); - for (n = gnode(h, 0); n < limit; n++) { /* traverse hash part */ - checkdeadkey(n); - if (ttisnil(gval(n))) /* entry is empty? */ - removeentry(n); /* remove it */ - else { - lua_assert(!ttisnil(gkey(n))); - markvalue(g, gkey(n)); /* mark key */ - markvalue(g, gval(n)); /* mark value */ - } - } -} - - -static lu_mem traversetable (global_State *g, Table *h) { - const char *weakkey, *weakvalue; - const TValue *mode = gfasttm(g, h->metatable, TM_MODE); - markobject(g, h->metatable); - if (mode && ttisstring(mode) && /* is there a weak mode? */ - ((weakkey = strchr(svalue(mode), 'k')), - (weakvalue = strchr(svalue(mode), 'v')), - (weakkey || weakvalue))) { /* is really weak? */ - black2gray(obj2gco(h)); /* keep table gray */ - if (!weakkey) /* strong keys? */ - traverseweakvalue(g, h); - else if (!weakvalue) /* strong values? */ - traverseephemeron(g, h); - else /* all weak */ - linktable(h, &g->allweak); /* nothing to traverse now */ - } - else /* not weak */ - traversestrongtable(g, h); - return sizeof(Table) + sizeof(TValue) * h->sizearray + - sizeof(Node) * cast(size_t, sizenode(h)); -} - - -static int traverseproto (global_State *g, Proto *f) { - int i; - if (f->cache && iswhite(obj2gco(f->cache))) - f->cache = NULL; /* allow cache to be collected */ - markobject(g, f->source); - for (i = 0; i < f->sizek; i++) /* mark literals */ - markvalue(g, &f->k[i]); - for (i = 0; i < f->sizeupvalues; i++) /* mark upvalue names */ - markobject(g, f->upvalues[i].name); - for (i = 0; i < f->sizep; i++) /* mark nested protos */ - markobject(g, f->p[i]); - for (i = 0; i < f->sizelocvars; i++) /* mark local-variable names */ - markobject(g, f->locvars[i].varname); - return sizeof(Proto) + sizeof(Instruction) * f->sizecode + - sizeof(Proto *) * f->sizep + - sizeof(TValue) * f->sizek + - sizeof(int) * f->sizelineinfo + - sizeof(LocVar) * f->sizelocvars + - sizeof(Upvaldesc) * f->sizeupvalues; -} - - -static lu_mem traverseCclosure (global_State *g, CClosure *cl) { - int i; - for (i = 0; i < cl->nupvalues; i++) /* mark its upvalues */ - markvalue(g, &cl->upvalue[i]); - return sizeCclosure(cl->nupvalues); -} - -static lu_mem traverseLclosure (global_State *g, LClosure *cl) { - int i; - markobject(g, cl->p); /* mark its prototype */ - for (i = 0; i < cl->nupvalues; i++) /* mark its upvalues */ - markobject(g, cl->upvals[i]); - return sizeLclosure(cl->nupvalues); -} - - -static lu_mem traversestack (global_State *g, lua_State *th) { - StkId o = th->stack; - if (o == NULL) - return 1; /* stack not completely built yet */ - for (; o < th->top; o++) - markvalue(g, o); - if (g->gcstate == GCSatomic) { /* final traversal? */ - StkId lim = th->stack + th->stacksize; /* real end of stack */ - for (; o < lim; o++) /* clear not-marked stack slice */ - setnilvalue(o); - } - return sizeof(lua_State) + sizeof(TValue) * th->stacksize; -} - - -/* -** traverse one gray object, turning it to black (except for threads, -** which are always gray). -*/ -static void propagatemark (global_State *g) { - lu_mem size; - GCObject *o = g->gray; - lua_assert(isgray(o)); - gray2black(o); - switch (gch(o)->tt) { - case LUA_TTABLE: { - Table *h = gco2t(o); - g->gray = h->gclist; /* remove from 'gray' list */ - size = traversetable(g, h); - break; - } - case LUA_TLCL: { - LClosure *cl = gco2lcl(o); - g->gray = cl->gclist; /* remove from 'gray' list */ - size = traverseLclosure(g, cl); - break; - } - case LUA_TCCL: { - CClosure *cl = gco2ccl(o); - g->gray = cl->gclist; /* remove from 'gray' list */ - size = traverseCclosure(g, cl); - break; - } - case LUA_TTHREAD: { - lua_State *th = gco2th(o); - g->gray = th->gclist; /* remove from 'gray' list */ - th->gclist = g->grayagain; - g->grayagain = o; /* insert into 'grayagain' list */ - black2gray(o); - size = traversestack(g, th); - break; - } - case LUA_TPROTO: { - Proto *p = gco2p(o); - g->gray = p->gclist; /* remove from 'gray' list */ - size = traverseproto(g, p); - break; - } - default: lua_assert(0); return; - } - g->GCmemtrav += size; -} - - -static void propagateall (global_State *g) { - while (g->gray) propagatemark(g); -} - - -static void propagatelist (global_State *g, GCObject *l) { - lua_assert(g->gray == NULL); /* no grays left */ - g->gray = l; - propagateall(g); /* traverse all elements from 'l' */ -} - -/* -** retraverse all gray lists. Because tables may be reinserted in other -** lists when traversed, traverse the original lists to avoid traversing -** twice the same table (which is not wrong, but inefficient) -*/ -static void retraversegrays (global_State *g) { - GCObject *weak = g->weak; /* save original lists */ - GCObject *grayagain = g->grayagain; - GCObject *ephemeron = g->ephemeron; - g->weak = g->grayagain = g->ephemeron = NULL; - propagateall(g); /* traverse main gray list */ - propagatelist(g, grayagain); - propagatelist(g, weak); - propagatelist(g, ephemeron); -} - - -static void convergeephemerons (global_State *g) { - int changed; - do { - GCObject *w; - GCObject *next = g->ephemeron; /* get ephemeron list */ - g->ephemeron = NULL; /* tables will return to this list when traversed */ - changed = 0; - while ((w = next) != NULL) { - next = gco2t(w)->gclist; - if (traverseephemeron(g, gco2t(w))) { /* traverse marked some value? */ - propagateall(g); /* propagate changes */ - changed = 1; /* will have to revisit all ephemeron tables */ - } - } - } while (changed); -} - -/* }====================================================== */ - - -/* -** {====================================================== -** Sweep Functions -** ======================================================= -*/ - - -/* -** clear entries with unmarked keys from all weaktables in list 'l' up -** to element 'f' -*/ -static void clearkeys (global_State *g, GCObject *l, GCObject *f) { - for (; l != f; l = gco2t(l)->gclist) { - Table *h = gco2t(l); - Node *n, *limit = gnodelast(h); - for (n = gnode(h, 0); n < limit; n++) { - if (!ttisnil(gval(n)) && (iscleared(g, gkey(n)))) { - setnilvalue(gval(n)); /* remove value ... */ - removeentry(n); /* and remove entry from table */ - } - } - } -} - - -/* -** clear entries with unmarked values from all weaktables in list 'l' up -** to element 'f' -*/ -static void clearvalues (global_State *g, GCObject *l, GCObject *f) { - for (; l != f; l = gco2t(l)->gclist) { - Table *h = gco2t(l); - Node *n, *limit = gnodelast(h); - int i; - for (i = 0; i < h->sizearray; i++) { - TValue *o = &h->array[i]; - if (iscleared(g, o)) /* value was collected? */ - setnilvalue(o); /* remove value */ - } - for (n = gnode(h, 0); n < limit; n++) { - if (!ttisnil(gval(n)) && iscleared(g, gval(n))) { - setnilvalue(gval(n)); /* remove value ... */ - removeentry(n); /* and remove entry from table */ - } - } - } -} - - -static void freeobj (lua_State *L, GCObject *o) { - switch (gch(o)->tt) { - case LUA_TPROTO: luaF_freeproto(L, gco2p(o)); break; - case LUA_TLCL: { - luaM_freemem(L, o, sizeLclosure(gco2lcl(o)->nupvalues)); - break; - } - case LUA_TCCL: { - luaM_freemem(L, o, sizeCclosure(gco2ccl(o)->nupvalues)); - break; - } - case LUA_TUPVAL: luaF_freeupval(L, gco2uv(o)); break; - case LUA_TTABLE: luaH_free(L, gco2t(o)); break; - case LUA_TTHREAD: luaE_freethread(L, gco2th(o)); break; - case LUA_TUSERDATA: luaM_freemem(L, o, sizeudata(gco2u(o))); break; - case LUA_TSHRSTR: - G(L)->strt.nuse--; - /* go through */ - case LUA_TLNGSTR: { - luaM_freemem(L, o, sizestring(gco2ts(o))); - break; - } - default: lua_assert(0); - } -} - - -#define sweepwholelist(L,p) sweeplist(L,p,MAX_LUMEM) -static GCObject **sweeplist (lua_State *L, GCObject **p, lu_mem count); - - -/* -** sweep the (open) upvalues of a thread and resize its stack and -** list of call-info structures. -*/ -static void sweepthread (lua_State *L, lua_State *L1) { - if (L1->stack == NULL) return; /* stack not completely built yet */ - sweepwholelist(L, &L1->openupval); /* sweep open upvalues */ - luaE_freeCI(L1); /* free extra CallInfo slots */ - /* should not change the stack during an emergency gc cycle */ - if (G(L)->gckind != KGC_EMERGENCY) - luaD_shrinkstack(L1); -} - - -/* -** sweep at most 'count' elements from a list of GCObjects erasing dead -** objects, where a dead (not alive) object is one marked with the "old" -** (non current) white and not fixed. -** In non-generational mode, change all non-dead objects back to white, -** preparing for next collection cycle. -** In generational mode, keep black objects black, and also mark them as -** old; stop when hitting an old object, as all objects after that -** one will be old too. -** When object is a thread, sweep its list of open upvalues too. -*/ -static GCObject **sweeplist (lua_State *L, GCObject **p, lu_mem count) { - global_State *g = G(L); - int ow = otherwhite(g); - int toclear, toset; /* bits to clear and to set in all live objects */ - int tostop; /* stop sweep when this is true */ - if (isgenerational(g)) { /* generational mode? */ - toclear = ~0; /* clear nothing */ - toset = bitmask(OLDBIT); /* set the old bit of all surviving objects */ - tostop = bitmask(OLDBIT); /* do not sweep old generation */ - } - else { /* normal mode */ - toclear = maskcolors; /* clear all color bits + old bit */ - toset = luaC_white(g); /* make object white */ - tostop = 0; /* do not stop */ - } - while (*p != NULL && count-- > 0) { - GCObject *curr = *p; - int marked = gch(curr)->marked; - if (isdeadm(ow, marked)) { /* is 'curr' dead? */ - *p = gch(curr)->next; /* remove 'curr' from list */ - freeobj(L, curr); /* erase 'curr' */ - } - else { - if (testbits(marked, tostop)) - return NULL; /* stop sweeping this list */ - if (gch(curr)->tt == LUA_TTHREAD) - sweepthread(L, gco2th(curr)); /* sweep thread's upvalues */ - /* update marks */ - gch(curr)->marked = cast_byte((marked & toclear) | toset); - p = &gch(curr)->next; /* go to next element */ - } - } - return (*p == NULL) ? NULL : p; -} - - -/* -** sweep a list until a live object (or end of list) -*/ -static GCObject **sweeptolive (lua_State *L, GCObject **p, int *n) { - GCObject ** old = p; - int i = 0; - do { - i++; - p = sweeplist(L, p, 1); - } while (p == old); - if (n) *n += i; - return p; -} - -/* }====================================================== */ - - -/* -** {====================================================== -** Finalization -** ======================================================= -*/ - -static void checkSizes (lua_State *L) { - global_State *g = G(L); - if (g->gckind != KGC_EMERGENCY) { /* do not change sizes in emergency */ - int hs = g->strt.size / 2; /* half the size of the string table */ - if (g->strt.nuse < cast(lu_int32, hs)) /* using less than that half? */ - luaS_resize(L, hs); /* halve its size */ - luaZ_freebuffer(L, &g->buff); /* free concatenation buffer */ - } -} - - -static GCObject *udata2finalize (global_State *g) { - GCObject *o = g->tobefnz; /* get first element */ - lua_assert(isfinalized(o)); - g->tobefnz = gch(o)->next; /* remove it from 'tobefnz' list */ - gch(o)->next = g->allgc; /* return it to 'allgc' list */ - g->allgc = o; - resetbit(gch(o)->marked, SEPARATED); /* mark that it is not in 'tobefnz' */ - lua_assert(!isold(o)); /* see MOVE OLD rule */ - if (!keepinvariantout(g)) /* not keeping invariant? */ - makewhite(g, o); /* "sweep" object */ - return o; -} - - -static void dothecall (lua_State *L, void *ud) { - UNUSED(ud); - luaD_call(L, L->top - 2, 0, 0); -} - - -static void GCTM (lua_State *L, int propagateerrors) { - global_State *g = G(L); - const TValue *tm; - TValue v; - setgcovalue(L, &v, udata2finalize(g)); - tm = luaT_gettmbyobj(L, &v, TM_GC); - if (tm != NULL && ttisfunction(tm)) { /* is there a finalizer? */ - int status; - lu_byte oldah = L->allowhook; - int running = g->gcrunning; - L->allowhook = 0; /* stop debug hooks during GC metamethod */ - g->gcrunning = 0; /* avoid GC steps */ - setobj2s(L, L->top, tm); /* push finalizer... */ - setobj2s(L, L->top + 1, &v); /* ... and its argument */ - L->top += 2; /* and (next line) call the finalizer */ - status = luaD_pcall(L, dothecall, NULL, savestack(L, L->top - 2), 0); - L->allowhook = oldah; /* restore hooks */ - g->gcrunning = running; /* restore state */ - if (status != LUA_OK && propagateerrors) { /* error while running __gc? */ - if (status == LUA_ERRRUN) { /* is there an error object? */ - const char *msg = (ttisstring(L->top - 1)) - ? svalue(L->top - 1) - : "no message"; - luaO_pushfstring(L, "error in __gc metamethod (%s)", msg); - status = LUA_ERRGCMM; /* error in __gc metamethod */ - } - luaD_throw(L, status); /* re-throw error */ - } - } -} - - -/* -** move all unreachable objects (or 'all' objects) that need -** finalization from list 'finobj' to list 'tobefnz' (to be finalized) -*/ -static void separatetobefnz (lua_State *L, int all) { - global_State *g = G(L); - GCObject **p = &g->finobj; - GCObject *curr; - GCObject **lastnext = &g->tobefnz; - /* find last 'next' field in 'tobefnz' list (to add elements in its end) */ - while (*lastnext != NULL) - lastnext = &gch(*lastnext)->next; - while ((curr = *p) != NULL) { /* traverse all finalizable objects */ - lua_assert(!isfinalized(curr)); - lua_assert(testbit(gch(curr)->marked, SEPARATED)); - if (!(iswhite(curr) || all)) /* not being collected? */ - p = &gch(curr)->next; /* don't bother with it */ - else { - l_setbit(gch(curr)->marked, FINALIZEDBIT); /* won't be finalized again */ - *p = gch(curr)->next; /* remove 'curr' from 'finobj' list */ - gch(curr)->next = *lastnext; /* link at the end of 'tobefnz' list */ - *lastnext = curr; - lastnext = &gch(curr)->next; - } - } -} - - -/* -** if object 'o' has a finalizer, remove it from 'allgc' list (must -** search the list to find it) and link it in 'finobj' list. -*/ -void luaC_checkfinalizer (lua_State *L, GCObject *o, Table *mt) { - global_State *g = G(L); - if (testbit(gch(o)->marked, SEPARATED) || /* obj. is already separated... */ - isfinalized(o) || /* ... or is finalized... */ - gfasttm(g, mt, TM_GC) == NULL) /* or has no finalizer? */ - return; /* nothing to be done */ - else { /* move 'o' to 'finobj' list */ - GCObject **p; - GCheader *ho = gch(o); - if (g->sweepgc == &ho->next) { /* avoid removing current sweep object */ - lua_assert(issweepphase(g)); - g->sweepgc = sweeptolive(L, g->sweepgc, NULL); - } - /* search for pointer pointing to 'o' */ - for (p = &g->allgc; *p != o; p = &gch(*p)->next) { /* empty */ } - *p = ho->next; /* remove 'o' from root list */ - ho->next = g->finobj; /* link it in list 'finobj' */ - g->finobj = o; - l_setbit(ho->marked, SEPARATED); /* mark it as such */ - if (!keepinvariantout(g)) /* not keeping invariant? */ - makewhite(g, o); /* "sweep" object */ - else - resetoldbit(o); /* see MOVE OLD rule */ - } -} - -/* }====================================================== */ - - -/* -** {====================================================== -** GC control -** ======================================================= -*/ - - -/* -** set a reasonable "time" to wait before starting a new GC cycle; -** cycle will start when memory use hits threshold -*/ -static void setpause (global_State *g, l_mem estimate) { - l_mem debt, threshold; - estimate = estimate / PAUSEADJ; /* adjust 'estimate' */ - threshold = (g->gcpause < MAX_LMEM / estimate) /* overflow? */ - ? estimate * g->gcpause /* no overflow */ - : MAX_LMEM; /* overflow; truncate to maximum */ - debt = -cast(l_mem, threshold - gettotalbytes(g)); - luaE_setdebt(g, debt); -} - - -#define sweepphases \ - (bitmask(GCSsweepstring) | bitmask(GCSsweepudata) | bitmask(GCSsweep)) - - -/* -** enter first sweep phase (strings) and prepare pointers for other -** sweep phases. The calls to 'sweeptolive' make pointers point to an -** object inside the list (instead of to the header), so that the real -** sweep do not need to skip objects created between "now" and the start -** of the real sweep. -** Returns how many objects it swept. -*/ -static int entersweep (lua_State *L) { - global_State *g = G(L); - int n = 0; - g->gcstate = GCSsweepstring; - lua_assert(g->sweepgc == NULL && g->sweepfin == NULL); - /* prepare to sweep strings, finalizable objects, and regular objects */ - g->sweepstrgc = 0; - g->sweepfin = sweeptolive(L, &g->finobj, &n); - g->sweepgc = sweeptolive(L, &g->allgc, &n); - return n; -} - - -/* -** change GC mode -*/ -void luaC_changemode (lua_State *L, int mode) { - global_State *g = G(L); - if (mode == g->gckind) return; /* nothing to change */ - if (mode == KGC_GEN) { /* change to generational mode */ - /* make sure gray lists are consistent */ - luaC_runtilstate(L, bitmask(GCSpropagate)); - g->GCestimate = gettotalbytes(g); - g->gckind = KGC_GEN; - } - else { /* change to incremental mode */ - /* sweep all objects to turn them back to white - (as white has not changed, nothing extra will be collected) */ - g->gckind = KGC_NORMAL; - entersweep(L); - luaC_runtilstate(L, ~sweepphases); - } -} - - -/* -** call all pending finalizers -*/ -static void callallpendingfinalizers (lua_State *L, int propagateerrors) { - global_State *g = G(L); - while (g->tobefnz) { - resetoldbit(g->tobefnz); - GCTM(L, propagateerrors); - } -} - - -void luaC_freeallobjects (lua_State *L) { - global_State *g = G(L); - int i; - separatetobefnz(L, 1); /* separate all objects with finalizers */ - lua_assert(g->finobj == NULL); - callallpendingfinalizers(L, 0); - g->currentwhite = WHITEBITS; /* this "white" makes all objects look dead */ - g->gckind = KGC_NORMAL; - sweepwholelist(L, &g->finobj); /* finalizers can create objs. in 'finobj' */ - sweepwholelist(L, &g->allgc); - for (i = 0; i < g->strt.size; i++) /* free all string lists */ - sweepwholelist(L, &g->strt.hash[i]); - lua_assert(g->strt.nuse == 0); -} - - -static l_mem atomic (lua_State *L) { - global_State *g = G(L); - l_mem work = -cast(l_mem, g->GCmemtrav); /* start counting work */ - GCObject *origweak, *origall; - lua_assert(!iswhite(obj2gco(g->mainthread))); - markobject(g, L); /* mark running thread */ - /* registry and global metatables may be changed by API */ - markvalue(g, &g->l_registry); - markmt(g); /* mark basic metatables */ - /* remark occasional upvalues of (maybe) dead threads */ - remarkupvals(g); - propagateall(g); /* propagate changes */ - work += g->GCmemtrav; /* stop counting (do not (re)count grays) */ - /* traverse objects caught by write barrier and by 'remarkupvals' */ - retraversegrays(g); - work -= g->GCmemtrav; /* restart counting */ - convergeephemerons(g); - /* at this point, all strongly accessible objects are marked. */ - /* clear values from weak tables, before checking finalizers */ - clearvalues(g, g->weak, NULL); - clearvalues(g, g->allweak, NULL); - origweak = g->weak; origall = g->allweak; - work += g->GCmemtrav; /* stop counting (objects being finalized) */ - separatetobefnz(L, 0); /* separate objects to be finalized */ - markbeingfnz(g); /* mark objects that will be finalized */ - propagateall(g); /* remark, to propagate `preserveness' */ - work -= g->GCmemtrav; /* restart counting */ - convergeephemerons(g); - /* at this point, all resurrected objects are marked. */ - /* remove dead objects from weak tables */ - clearkeys(g, g->ephemeron, NULL); /* clear keys from all ephemeron tables */ - clearkeys(g, g->allweak, NULL); /* clear keys from all allweak tables */ - /* clear values from resurrected weak tables */ - clearvalues(g, g->weak, origweak); - clearvalues(g, g->allweak, origall); - g->currentwhite = cast_byte(otherwhite(g)); /* flip current white */ - work += g->GCmemtrav; /* complete counting */ - return work; /* estimate of memory marked by 'atomic' */ -} - - -static lu_mem singlestep (lua_State *L) { - global_State *g = G(L); - switch (g->gcstate) { - case GCSpause: { - /* start to count memory traversed */ - g->GCmemtrav = g->strt.size * sizeof(GCObject*); - lua_assert(!isgenerational(g)); - restartcollection(g); - g->gcstate = GCSpropagate; - return g->GCmemtrav; - } - case GCSpropagate: { - if (g->gray) { - lu_mem oldtrav = g->GCmemtrav; - propagatemark(g); - return g->GCmemtrav - oldtrav; /* memory traversed in this step */ - } - else { /* no more `gray' objects */ - lu_mem work; - int sw; - g->gcstate = GCSatomic; /* finish mark phase */ - g->GCestimate = g->GCmemtrav; /* save what was counted */; - work = atomic(L); /* add what was traversed by 'atomic' */ - g->GCestimate += work; /* estimate of total memory traversed */ - sw = entersweep(L); - return work + sw * GCSWEEPCOST; - } - } - case GCSsweepstring: { - int i; - for (i = 0; i < GCSWEEPMAX && g->sweepstrgc + i < g->strt.size; i++) - sweepwholelist(L, &g->strt.hash[g->sweepstrgc + i]); - g->sweepstrgc += i; - if (g->sweepstrgc >= g->strt.size) /* no more strings to sweep? */ - g->gcstate = GCSsweepudata; - return i * GCSWEEPCOST; - } - case GCSsweepudata: { - if (g->sweepfin) { - g->sweepfin = sweeplist(L, g->sweepfin, GCSWEEPMAX); - return GCSWEEPMAX*GCSWEEPCOST; - } - else { - g->gcstate = GCSsweep; - return 0; - } - } - case GCSsweep: { - if (g->sweepgc) { - g->sweepgc = sweeplist(L, g->sweepgc, GCSWEEPMAX); - return GCSWEEPMAX*GCSWEEPCOST; - } - else { - /* sweep main thread */ - GCObject *mt = obj2gco(g->mainthread); - sweeplist(L, &mt, 1); - checkSizes(L); - g->gcstate = GCSpause; /* finish collection */ - return GCSWEEPCOST; - } - } - default: lua_assert(0); return 0; - } -} - - -/* -** advances the garbage collector until it reaches a state allowed -** by 'statemask' -*/ -void luaC_runtilstate (lua_State *L, int statesmask) { - global_State *g = G(L); - while (!testbit(statesmask, g->gcstate)) - singlestep(L); -} - - -static void generationalcollection (lua_State *L) { - global_State *g = G(L); - lua_assert(g->gcstate == GCSpropagate); - if (g->GCestimate == 0) { /* signal for another major collection? */ - luaC_fullgc(L, 0); /* perform a full regular collection */ - g->GCestimate = gettotalbytes(g); /* update control */ - } - else { - lu_mem estimate = g->GCestimate; - luaC_runtilstate(L, bitmask(GCSpause)); /* run complete (minor) cycle */ - g->gcstate = GCSpropagate; /* skip restart */ - if (gettotalbytes(g) > (estimate / 100) * g->gcmajorinc) - g->GCestimate = 0; /* signal for a major collection */ - else - g->GCestimate = estimate; /* keep estimate from last major coll. */ - - } - setpause(g, gettotalbytes(g)); - lua_assert(g->gcstate == GCSpropagate); -} - - -static void incstep (lua_State *L) { - global_State *g = G(L); - l_mem debt = g->GCdebt; - int stepmul = g->gcstepmul; - if (stepmul < 40) stepmul = 40; /* avoid ridiculous low values (and 0) */ - /* convert debt from Kb to 'work units' (avoid zero debt and overflows) */ - debt = (debt / STEPMULADJ) + 1; - debt = (debt < MAX_LMEM / stepmul) ? debt * stepmul : MAX_LMEM; - do { /* always perform at least one single step */ - lu_mem work = singlestep(L); /* do some work */ - debt -= work; - } while (debt > -GCSTEPSIZE && g->gcstate != GCSpause); - if (g->gcstate == GCSpause) - setpause(g, g->GCestimate); /* pause until next cycle */ - else { - debt = (debt / stepmul) * STEPMULADJ; /* convert 'work units' to Kb */ - luaE_setdebt(g, debt); - } -} - - -/* -** performs a basic GC step -*/ -void luaC_forcestep (lua_State *L) { - global_State *g = G(L); - int i; - if (isgenerational(g)) generationalcollection(L); - else incstep(L); - /* run a few finalizers (or all of them at the end of a collect cycle) */ - for (i = 0; g->tobefnz && (i < GCFINALIZENUM || g->gcstate == GCSpause); i++) - GCTM(L, 1); /* call one finalizer */ -} - - -/* -** performs a basic GC step only if collector is running -*/ -void luaC_step (lua_State *L) { - global_State *g = G(L); - if (g->gcrunning) luaC_forcestep(L); - else luaE_setdebt(g, -GCSTEPSIZE); /* avoid being called too often */ -} - - - -/* -** performs a full GC cycle; if "isemergency", does not call -** finalizers (which could change stack positions) -*/ -void luaC_fullgc (lua_State *L, int isemergency) { - global_State *g = G(L); - int origkind = g->gckind; - lua_assert(origkind != KGC_EMERGENCY); - if (isemergency) /* do not run finalizers during emergency GC */ - g->gckind = KGC_EMERGENCY; - else { - g->gckind = KGC_NORMAL; - callallpendingfinalizers(L, 1); - } - if (keepinvariant(g)) { /* may there be some black objects? */ - /* must sweep all objects to turn them back to white - (as white has not changed, nothing will be collected) */ - entersweep(L); - } - /* finish any pending sweep phase to start a new cycle */ - luaC_runtilstate(L, bitmask(GCSpause)); - luaC_runtilstate(L, ~bitmask(GCSpause)); /* start new collection */ - luaC_runtilstate(L, bitmask(GCSpause)); /* run entire collection */ - if (origkind == KGC_GEN) { /* generational mode? */ - /* generational mode must be kept in propagate phase */ - luaC_runtilstate(L, bitmask(GCSpropagate)); - } - g->gckind = origkind; - setpause(g, gettotalbytes(g)); - if (!isemergency) /* do not run finalizers during emergency GC */ - callallpendingfinalizers(L, 1); -} - -/* }====================================================== */ - - |