diff options
Diffstat (limited to 'lib/LuaBridge/Tests/Lua/Lua.5.2.0/src/lgc.c')
| -rw-r--r-- | lib/LuaBridge/Tests/Lua/Lua.5.2.0/src/lgc.c | 1103 |
1 files changed, 1103 insertions, 0 deletions
diff --git a/lib/LuaBridge/Tests/Lua/Lua.5.2.0/src/lgc.c b/lib/LuaBridge/Tests/Lua/Lua.5.2.0/src/lgc.c new file mode 100644 index 0000000..cdd92e5 --- /dev/null +++ b/lib/LuaBridge/Tests/Lua/Lua.5.2.0/src/lgc.c @@ -0,0 +1,1103 @@ +/* +** $Id: lgc.c,v 2.116 2011/12/02 13:18:41 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" + + + +/* how much to allocate before next GC step */ +#define GCSTEPSIZE 1024 + +/* maximum number of elements to sweep in each single step */ +#define GCSWEEPMAX 40 + +/* cost of sweeping one element */ +#define GCSWEEPCOST 1 + +/* maximum number of finalizers to call in each GC step */ +#define GCFINALIZENUM 4 + +/* cost of marking the root set */ +#define GCROOTCOST 10 + +/* cost of atomic step */ +#define GCATOMICCOST 1000 + +/* basic cost to traverse one object (to be added to the links the + object may have) */ +#define TRAVCOST 5 + + +/* +** standard negative debt for GC; a reasonable "time" to wait before +** starting a new cycle +*/ +#define stddebt(g) (-cast(l_mem, gettotalbytes(g)/100) * g->gcpause) + + +/* +** '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 stringmark(s) ((void)((s) && resetbits((s)->tsv.marked, WHITEBITS))) + + +#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 (const TValue *o) { + if (!iscollectable(o)) return 0; + else if (ttisstring(o)) { + stringmark(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(isgenerational(g) || g->gcstate != GCSpause); + lua_assert(gch(o)->tt != LUA_TTABLE); + if (keepinvariant(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); + GCObject *o = obj2gco(cast(char *, luaM_newobject(L, tt, sz)) + 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 and closed upvalues are visited and turned +** black here. Strings remain gray (it is the same as making them +** black). 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) { + lua_assert(iswhite(o) && !isdead(g, o)); + white2gray(o); + switch (gch(o)->tt) { + case LUA_TSTRING: { + return; /* for strings, gray is as good as black */ + } + case LUA_TUSERDATA: { + Table *mt = gco2u(o)->metatable; + markobject(g, mt); + markobject(g, gco2u(o)->env); + gray2black(o); /* all pointers marked */ + return; + } + case LUA_TUPVAL: { + UpVal *uv = gco2uv(o); + markvalue(g, uv->v); + if (uv->v == &uv->u.value) /* closed? (open upvalues remain gray) */ + gray2black(o); /* make it black */ + return; + } + case LUA_TFUNCTION: { + gco2cl(o)->c.gclist = g->gray; + g->gray = o; + break; + } + case LUA_TTABLE: { + linktable(gco2t(o), &g->gray); + break; + } + case LUA_TTHREAD: { + gco2th(o)->gclist = g->gray; + g->gray = o; + break; + } + case LUA_TPROTO: { + gco2p(o)->gclist = g->gray; + g->gray = o; + break; + } + default: lua_assert(0); + } +} + + +/* +** 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 markroot (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(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(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 int traversetable (global_State *g, Table *h) { + const TValue *mode = gfasttm(g, h->metatable, TM_MODE); + markobject(g, h->metatable); + if (mode && ttisstring(mode)) { /* is there a weak mode? */ + int weakkey = (strchr(svalue(mode), 'k') != NULL); + int weakvalue = (strchr(svalue(mode), 'v') != NULL); + if (weakkey || weakvalue) { /* is really weak? */ + black2gray(obj2gco(h)); /* keep table gray */ + if (!weakkey) { /* strong keys? */ + traverseweakvalue(g, h); + return TRAVCOST + sizenode(h); + } + else if (!weakvalue) { /* strong values? */ + traverseephemeron(g, h); + return TRAVCOST + h->sizearray + sizenode(h); + } + else { + linktable(h, &g->allweak); /* nothing to traverse now */ + return TRAVCOST; + } + } /* else go through */ + } + traversestrongtable(g, h); + return TRAVCOST + h->sizearray + (2 * 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 */ + stringmark(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 */ + stringmark(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 */ + stringmark(f->locvars[i].varname); + return TRAVCOST + f->sizek + f->sizeupvalues + f->sizep + f->sizelocvars; +} + + +static int traverseclosure (global_State *g, Closure *cl) { + if (cl->c.isC) { + int i; + for (i=0; i<cl->c.nupvalues; i++) /* mark its upvalues */ + markvalue(g, &cl->c.upvalue[i]); + } + else { + int i; + lua_assert(cl->l.nupvalues == cl->l.p->sizeupvalues); + markobject(g, cl->l.p); /* mark its prototype */ + for (i=0; i<cl->l.nupvalues; i++) /* mark its upvalues */ + markobject(g, cl->l.upvals[i]); + } + return TRAVCOST + cl->c.nupvalues; +} + + +static int traversestack (global_State *g, lua_State *L) { + StkId o = L->stack; + if (o == NULL) + return 1; /* stack not completely built yet */ + for (; o < L->top; o++) + markvalue(g, o); + if (g->gcstate == GCSatomic) { /* final traversal? */ + StkId lim = L->stack + L->stacksize; /* real end of stack */ + for (; o < lim; o++) /* clear not-marked stack slice */ + setnilvalue(o); + } + return TRAVCOST + cast_int(o - L->stack); +} + + +/* +** traverse one gray object, turning it to black (except for threads, +** which are always gray). +** Returns number of values traversed. +*/ +static int propagatemark (global_State *g) { + 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; + return traversetable(g, h); + } + case LUA_TFUNCTION: { + Closure *cl = gco2cl(o); + g->gray = cl->c.gclist; + return traverseclosure(g, cl); + } + case LUA_TTHREAD: { + lua_State *th = gco2th(o); + g->gray = th->gclist; + th->gclist = g->grayagain; + g->grayagain = o; + black2gray(o); + return traversestack(g, th); + } + case LUA_TPROTO: { + Proto *p = gco2p(o); + g->gray = p->gclist; + return traverseproto(g, p); + } + default: lua_assert(0); return 0; + } +} + + +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 (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(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 (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(o)) /* value was collected? */ + setnilvalue(o); /* remove value */ + } + for (n = gnode(h, 0); n < limit; n++) { + if (!ttisnil(gval(n)) && iscleared(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_TFUNCTION: luaF_freeclosure(L, gco2cl(o)); 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_TSTRING: { + G(L)->strt.nuse--; + 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 */ + l_mem debt = g->GCdebt; /* current debt */ + 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 (gch(curr)->tt == LUA_TTHREAD) + sweepthread(L, gco2th(curr)); /* sweep thread's upvalues */ + if (testbits(marked, tostop)) { + static GCObject *nullp = NULL; + p = &nullp; /* stop sweeping this list */ + break; + } + /* update marks */ + gch(curr)->marked = cast_byte((marked & toclear) | toset); + p = &gch(curr)->next; /* go to next element */ + } + } + luaE_setdebt(g, debt); /* sweeping should not change debt */ + 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 (!keepinvariant(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 msg.? */ + luaO_pushfstring(L, "error in __gc metamethod (%s)", + lua_tostring(L, -1)); + status = LUA_ERRGCMM; /* error in __gc metamethod */ + } + luaD_throw(L, status); /* re-send 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 (!(all || iswhite(curr))) /* 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; + for (p = &g->allgc; *p != o; p = &gch(*p)->next) ; + *p = gch(o)->next; /* remove 'o' from root list */ + gch(o)->next = g->finobj; /* link it in list 'finobj' */ + g->finobj = o; + l_setbit(gch(o)->marked, SEPARATED); /* mark it as such */ + resetoldbit(o); /* see MOVE OLD rule */ + } +} + +/* }====================================================== */ + + +/* +** {====================================================== +** GC control +** ======================================================= +*/ + + +#define sweepphases \ + (bitmask(GCSsweepstring) | bitmask(GCSsweepudata) | bitmask(GCSsweep)) + +/* +** 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->lastmajormem = 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->sweepstrgc = 0; + g->gcstate = GCSsweepstring; + g->gckind = KGC_NORMAL; + 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 void atomic (lua_State *L) { + global_State *g = G(L); + 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); + /* traverse objects caught by write barrier and by 'remarkupvals' */ + retraversegrays(g); + convergeephemerons(g); + /* at this point, all strongly accessible objects are marked. */ + /* clear values from weak tables, before checking finalizers */ + clearvalues(g->weak, NULL); + clearvalues(g->allweak, NULL); + origweak = g->weak; origall = g->allweak; + separatetobefnz(L, 0); /* separate objects to be finalized */ + markbeingfnz(g); /* mark userdata that will be finalized */ + propagateall(g); /* remark, to propagate `preserveness' */ + convergeephemerons(g); + /* at this point, all resurrected objects are marked. */ + /* remove dead objects from weak tables */ + clearkeys(g->ephemeron, NULL); /* clear keys from all ephemeron tables */ + clearkeys(g->allweak, NULL); /* clear keys from all allweak tables */ + /* clear values from resurrected weak tables */ + clearvalues(g->weak, origweak); + clearvalues(g->allweak, origall); + g->sweepstrgc = 0; /* prepare to sweep strings */ + g->gcstate = GCSsweepstring; + g->currentwhite = cast_byte(otherwhite(g)); /* flip current white */ + /*lua_checkmemory(L);*/ +} + + +static l_mem singlestep (lua_State *L) { + global_State *g = G(L); + switch (g->gcstate) { + case GCSpause: { + if (!isgenerational(g)) + markroot(g); /* start a new collection */ + /* in any case, root must be marked */ + lua_assert(!iswhite(obj2gco(g->mainthread)) + && !iswhite(gcvalue(&g->l_registry))); + g->gcstate = GCSpropagate; + return GCROOTCOST; + } + case GCSpropagate: { + if (g->gray) + return propagatemark(g); + else { /* no more `gray' objects */ + g->gcstate = GCSatomic; /* finish mark phase */ + atomic(L); + return GCATOMICCOST; + } + } + case GCSsweepstring: { + if (g->sweepstrgc < g->strt.size) { + sweepwholelist(L, &g->strt.hash[g->sweepstrgc++]); + return GCSWEEPCOST; + } + else { /* no more strings to sweep */ + g->sweepgc = &g->finobj; /* prepare to sweep finalizable objects */ + g->gcstate = GCSsweepudata; + return 0; + } + } + case GCSsweepudata: { + if (*g->sweepgc) { + g->sweepgc = sweeplist(L, g->sweepgc, GCSWEEPMAX); + return GCSWEEPMAX*GCSWEEPCOST; + } + else { + g->sweepgc = &g->allgc; /* go to next phase */ + g->gcstate = GCSsweep; + return GCSWEEPCOST; + } + } + 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); + if (g->lastmajormem == 0) { /* signal for another major collection? */ + luaC_fullgc(L, 0); /* perform a full regular collection */ + g->lastmajormem = gettotalbytes(g); /* update control */ + } + else { + luaC_runtilstate(L, ~bitmask(GCSpause)); /* run complete cycle */ + luaC_runtilstate(L, bitmask(GCSpause)); + if (gettotalbytes(g) > g->lastmajormem/100 * g->gcmajorinc) + g->lastmajormem = 0; /* signal for a major collection */ + } + luaE_setdebt(g, stddebt(g)); +} + + +static void step (lua_State *L) { + global_State *g = G(L); + l_mem lim = g->gcstepmul; /* how much to work */ + do { /* always perform at least one single step */ + lim -= singlestep(L); + } while (lim > 0 && g->gcstate != GCSpause); + if (g->gcstate != GCSpause) + luaE_setdebt(g, g->GCdebt - GCSTEPSIZE); + else + luaE_setdebt(g, stddebt(g)); +} + + +/* +** performs a basic GC step even if the collector is stopped +*/ +void luaC_forcestep (lua_State *L) { + global_State *g = G(L); + int i; + if (isgenerational(g)) generationalcollection(L); + else step(L); + for (i = 0; i < GCFINALIZENUM && g->tobefnz; i++) + GCTM(L, 1); /* Call a few pending finalizers */ +} + + +/* +** performs a basic GC step only if collector is running +*/ +void luaC_step (lua_State *L) { + if (G(L)->gcrunning) luaC_forcestep(L); +} + + +/* +** 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 */ + callallpendingfinalizers(L, 1); + if (keepinvariant(g)) { /* marking phase? */ + /* must sweep all objects to turn them back to white + (as white has not changed, nothing will be collected) */ + g->sweepstrgc = 0; + g->gcstate = GCSsweepstring; + } + g->gckind = isemergency ? KGC_EMERGENCY : KGC_NORMAL; + /* finish any pending sweep phase to start a new cycle */ + luaC_runtilstate(L, bitmask(GCSpause)); + /* run entire collector */ + luaC_runtilstate(L, ~bitmask(GCSpause)); + luaC_runtilstate(L, bitmask(GCSpause)); + if (origkind == KGC_GEN) { /* generational mode? */ + /* generational mode must always start in propagate phase */ + luaC_runtilstate(L, bitmask(GCSpropagate)); + } + g->gckind = origkind; + luaE_setdebt(g, stddebt(g)); + if (!isemergency) /* do not run finalizers during emergency GC */ + callallpendingfinalizers(L, 1); +} + +/* }====================================================== */ + + |