+++ /dev/null
-/*
-** $Id: lgc.c,v 2.38.1.2 2011/03/18 18:05:38 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"
-
-
-#define GCSTEPSIZE 1024u
-#define GCSWEEPMAX 40
-#define GCSWEEPCOST 10
-#define GCFINALIZECOST 100
-
-
-#define maskmarks cast_byte(~(bitmask(BLACKBIT)|WHITEBITS))
-
-#define makewhite(g,x) \
- ((x)->gch.marked = cast_byte(((x)->gch.marked & maskmarks) | luaC_white(g)))
-
-#define white2gray(x) reset2bits((x)->gch.marked, WHITE0BIT, WHITE1BIT)
-#define black2gray(x) resetbit((x)->gch.marked, BLACKBIT)
-
-#define stringmark(s) reset2bits((s)->tsv.marked, WHITE0BIT, WHITE1BIT)
-
-
-#define isfinalized(u) testbit((u)->marked, FINALIZEDBIT)
-#define markfinalized(u) l_setbit((u)->marked, FINALIZEDBIT)
-
-
-#define KEYWEAK bitmask(KEYWEAKBIT)
-#define VALUEWEAK bitmask(VALUEWEAKBIT)
-
-
-
-#define markvalue(g,o) { checkconsistency(o); \
- if (iscollectable(o) && iswhite(gcvalue(o))) reallymarkobject(g,gcvalue(o)); }
-
-#define markobject(g,t) { if (iswhite(obj2gco(t))) \
- reallymarkobject(g, obj2gco(t)); }
-
-
-#define setthreshold(g) (g->GCthreshold = (g->estimate/100) * g->gcpause)
-
-
-static void removeentry (Node *n) {
- lua_assert(ttisnil(gval(n)));
- if (iscollectable(gkey(n)))
- setttype(gkey(n), LUA_TDEADKEY); /* dead key; remove it */
-}
-
-
-static void reallymarkobject (global_State *g, GCObject *o) {
- lua_assert(iswhite(o) && !isdead(g, o));
- white2gray(o);
- switch (o->gch.tt) {
- case LUA_TSTRING: {
- return;
- }
- case LUA_TUSERDATA: {
- Table *mt = gco2u(o)->metatable;
- gray2black(o); /* udata are never gray */
- if (mt) markobject(g, mt);
- markobject(g, gco2u(o)->env);
- return;
- }
- case LUA_TUPVAL: {
- UpVal *uv = gco2uv(o);
- markvalue(g, uv->v);
- if (uv->v == &uv->u.value) /* closed? */
- gray2black(o); /* open upvalues are never black */
- return;
- }
- case LUA_TFUNCTION: {
- gco2cl(o)->c.gclist = g->gray;
- g->gray = o;
- break;
- }
- case LUA_TTABLE: {
- gco2h(o)->gclist = g->gray;
- g->gray = o;
- 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);
- }
-}
-
-
-static void marktmu (global_State *g) {
- GCObject *u = g->tmudata;
- if (u) {
- do {
- u = u->gch.next;
- makewhite(g, u); /* may be marked, if left from previous GC */
- reallymarkobject(g, u);
- } while (u != g->tmudata);
- }
-}
-
-
-/* move `dead' udata that need finalization to list `tmudata' */
-size_t luaC_separateudata (lua_State *L, int all) {
- global_State *g = G(L);
- size_t deadmem = 0;
- GCObject **p = &g->mainthread->next;
- GCObject *curr;
- while ((curr = *p) != NULL) {
- if (!(iswhite(curr) || all) || isfinalized(gco2u(curr)))
- p = &curr->gch.next; /* don't bother with them */
- else if (fasttm(L, gco2u(curr)->metatable, TM_GC) == NULL) {
- markfinalized(gco2u(curr)); /* don't need finalization */
- p = &curr->gch.next;
- }
- else { /* must call its gc method */
- deadmem += sizeudata(gco2u(curr));
- markfinalized(gco2u(curr));
- *p = curr->gch.next;
- /* link `curr' at the end of `tmudata' list */
- if (g->tmudata == NULL) /* list is empty? */
- g->tmudata = curr->gch.next = curr; /* creates a circular list */
- else {
- curr->gch.next = g->tmudata->gch.next;
- g->tmudata->gch.next = curr;
- g->tmudata = curr;
- }
- }
- }
- return deadmem;
-}
-
-
-static int traversetable (global_State *g, Table *h) {
- int i;
- int weakkey = 0;
- int weakvalue = 0;
- const TValue *mode;
- if (h->metatable)
- markobject(g, h->metatable);
- mode = gfasttm(g, h->metatable, TM_MODE);
- if (mode && ttisstring(mode)) { /* is there a weak mode? */
- weakkey = (strchr(svalue(mode), 'k') != NULL);
- weakvalue = (strchr(svalue(mode), 'v') != NULL);
- if (weakkey || weakvalue) { /* is really weak? */
- h->marked &= ~(KEYWEAK | VALUEWEAK); /* clear bits */
- h->marked |= cast_byte((weakkey << KEYWEAKBIT) |
- (weakvalue << VALUEWEAKBIT));
- h->gclist = g->weak; /* must be cleared after GC, ... */
- g->weak = obj2gco(h); /* ... so put in the appropriate list */
- }
- }
- if (weakkey && weakvalue) return 1;
- if (!weakvalue) {
- i = h->sizearray;
- while (i--)
- markvalue(g, &h->array[i]);
- }
- i = sizenode(h);
- while (i--) {
- Node *n = gnode(h, i);
- lua_assert(ttype(gkey(n)) != LUA_TDEADKEY || ttisnil(gval(n)));
- if (ttisnil(gval(n)))
- removeentry(n); /* remove empty entries */
- else {
- lua_assert(!ttisnil(gkey(n)));
- if (!weakkey) markvalue(g, gkey(n));
- if (!weakvalue) markvalue(g, gval(n));
- }
- }
- return weakkey || weakvalue;
-}
-
-
-/*
-** All marks are conditional because a GC may happen while the
-** prototype is still being created
-*/
-static void traverseproto (global_State *g, Proto *f) {
- int i;
- if (f->source) 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 */
- if (f->upvalues[i])
- stringmark(f->upvalues[i]);
- }
- for (i=0; i<f->sizep; i++) { /* mark nested protos */
- if (f->p[i])
- markobject(g, f->p[i]);
- }
- for (i=0; i<f->sizelocvars; i++) { /* mark local-variable names */
- if (f->locvars[i].varname)
- stringmark(f->locvars[i].varname);
- }
-}
-
-
-
-static void traverseclosure (global_State *g, Closure *cl) {
- markobject(g, cl->c.env);
- 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->nups);
- markobject(g, cl->l.p);
- for (i=0; i<cl->l.nupvalues; i++) /* mark its upvalues */
- markobject(g, cl->l.upvals[i]);
- }
-}
-
-
-static void checkstacksizes (lua_State *L, StkId max) {
- int ci_used = cast_int(L->ci - L->base_ci); /* number of `ci' in use */
- int s_used = cast_int(max - L->stack); /* part of stack in use */
- if (L->size_ci > LUAI_MAXCALLS) /* handling overflow? */
- return; /* do not touch the stacks */
- if (4*ci_used < L->size_ci && 2*BASIC_CI_SIZE < L->size_ci)
- luaD_reallocCI(L, L->size_ci/2); /* still big enough... */
- condhardstacktests(luaD_reallocCI(L, ci_used + 1));
- if (4*s_used < L->stacksize &&
- 2*(BASIC_STACK_SIZE+EXTRA_STACK) < L->stacksize)
- luaD_reallocstack(L, L->stacksize/2); /* still big enough... */
- condhardstacktests(luaD_reallocstack(L, s_used));
-}
-
-
-static void traversestack (global_State *g, lua_State *l) {
- StkId o, lim;
- CallInfo *ci;
- markvalue(g, gt(l));
- lim = l->top;
- for (ci = l->base_ci; ci <= l->ci; ci++) {
- lua_assert(ci->top <= l->stack_last);
- if (lim < ci->top) lim = ci->top;
- }
- for (o = l->stack; o < l->top; o++)
- markvalue(g, o);
- for (; o <= lim; o++)
- setnilvalue(o);
- checkstacksizes(l, lim);
-}
-
-
-/*
-** traverse one gray object, turning it to black.
-** Returns `quantity' traversed.
-*/
-static l_mem propagatemark (global_State *g) {
- GCObject *o = g->gray;
- lua_assert(isgray(o));
- gray2black(o);
- switch (o->gch.tt) {
- case LUA_TTABLE: {
- Table *h = gco2h(o);
- g->gray = h->gclist;
- if (traversetable(g, h)) /* table is weak? */
- black2gray(o); /* keep it gray */
- return sizeof(Table) + sizeof(TValue) * h->sizearray +
- sizeof(Node) * sizenode(h);
- }
- case LUA_TFUNCTION: {
- Closure *cl = gco2cl(o);
- g->gray = cl->c.gclist;
- traverseclosure(g, cl);
- return (cl->c.isC) ? sizeCclosure(cl->c.nupvalues) :
- sizeLclosure(cl->l.nupvalues);
- }
- case LUA_TTHREAD: {
- lua_State *th = gco2th(o);
- g->gray = th->gclist;
- th->gclist = g->grayagain;
- g->grayagain = o;
- black2gray(o);
- traversestack(g, th);
- return sizeof(lua_State) + sizeof(TValue) * th->stacksize +
- sizeof(CallInfo) * th->size_ci;
- }
- case LUA_TPROTO: {
- Proto *p = gco2p(o);
- g->gray = p->gclist;
- traverseproto(g, p);
- return sizeof(Proto) + sizeof(Instruction) * p->sizecode +
- sizeof(Proto *) * p->sizep +
- sizeof(TValue) * p->sizek +
- sizeof(int) * p->sizelineinfo +
- sizeof(LocVar) * p->sizelocvars +
- sizeof(TString *) * p->sizeupvalues;
- }
- default: lua_assert(0); return 0;
- }
-}
-
-
-static size_t propagateall (global_State *g) {
- size_t m = 0;
- while (g->gray) m += propagatemark(g);
- return m;
-}
-
-
-/*
-** The next function 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 userdata
-** being finalized, keep them in keys, but not in values
-*/
-static int iscleared (const TValue *o, int iskey) {
- if (!iscollectable(o)) return 0;
- if (ttisstring(o)) {
- stringmark(rawtsvalue(o)); /* strings are `values', so are never weak */
- return 0;
- }
- return iswhite(gcvalue(o)) ||
- (ttisuserdata(o) && (!iskey && isfinalized(uvalue(o))));
-}
-
-
-/*
-** clear collected entries from weaktables
-*/
-static void cleartable (GCObject *l) {
- while (l) {
- Table *h = gco2h(l);
- int i = h->sizearray;
- lua_assert(testbit(h->marked, VALUEWEAKBIT) ||
- testbit(h->marked, KEYWEAKBIT));
- if (testbit(h->marked, VALUEWEAKBIT)) {
- while (i--) {
- TValue *o = &h->array[i];
- if (iscleared(o, 0)) /* value was collected? */
- setnilvalue(o); /* remove value */
- }
- }
- i = sizenode(h);
- while (i--) {
- Node *n = gnode(h, i);
- if (!ttisnil(gval(n)) && /* non-empty entry? */
- (iscleared(key2tval(n), 1) || iscleared(gval(n), 0))) {
- setnilvalue(gval(n)); /* remove value ... */
- removeentry(n); /* remove entry from table */
- }
- }
- l = h->gclist;
- }
-}
-
-
-static void freeobj (lua_State *L, GCObject *o) {
- switch (o->gch.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, gco2h(o)); break;
- case LUA_TTHREAD: {
- lua_assert(gco2th(o) != L && gco2th(o) != G(L)->mainthread);
- luaE_freethread(L, gco2th(o));
- break;
- }
- case LUA_TSTRING: {
- G(L)->strt.nuse--;
- luaM_freemem(L, o, sizestring(gco2ts(o)));
- break;
- }
- case LUA_TUSERDATA: {
- luaM_freemem(L, o, sizeudata(gco2u(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) {
- GCObject *curr;
- global_State *g = G(L);
- int deadmask = otherwhite(g);
- while ((curr = *p) != NULL && count-- > 0) {
- if (curr->gch.tt == LUA_TTHREAD) /* sweep open upvalues of each thread */
- sweepwholelist(L, &gco2th(curr)->openupval);
- if ((curr->gch.marked ^ WHITEBITS) & deadmask) { /* not dead? */
- lua_assert(!isdead(g, curr) || testbit(curr->gch.marked, FIXEDBIT));
- makewhite(g, curr); /* make it white (for next cycle) */
- p = &curr->gch.next;
- }
- else { /* must erase `curr' */
- lua_assert(isdead(g, curr) || deadmask == bitmask(SFIXEDBIT));
- *p = curr->gch.next;
- if (curr == g->rootgc) /* is the first element of the list? */
- g->rootgc = curr->gch.next; /* adjust first */
- freeobj(L, curr);
- }
- }
- return p;
-}
-
-
-static void checkSizes (lua_State *L) {
- global_State *g = G(L);
- /* check size of string hash */
- if (g->strt.nuse < cast(lu_int32, g->strt.size/4) &&
- g->strt.size > MINSTRTABSIZE*2)
- luaS_resize(L, g->strt.size/2); /* table is too big */
- /* check size of buffer */
- if (luaZ_sizebuffer(&g->buff) > LUA_MINBUFFER*2) { /* buffer too big? */
- size_t newsize = luaZ_sizebuffer(&g->buff) / 2;
- luaZ_resizebuffer(L, &g->buff, newsize);
- }
-}
-
-
-static void GCTM (lua_State *L) {
- global_State *g = G(L);
- GCObject *o = g->tmudata->gch.next; /* get first element */
- Udata *udata = rawgco2u(o);
- const TValue *tm;
- /* remove udata from `tmudata' */
- if (o == g->tmudata) /* last element? */
- g->tmudata = NULL;
- else
- g->tmudata->gch.next = udata->uv.next;
- udata->uv.next = g->mainthread->next; /* return it to `root' list */
- g->mainthread->next = o;
- makewhite(g, o);
- tm = fasttm(L, udata->uv.metatable, TM_GC);
- if (tm != NULL) {
- lu_byte oldah = L->allowhook;
- lu_mem oldt = g->GCthreshold;
- L->allowhook = 0; /* stop debug hooks during GC tag method */
- g->GCthreshold = 2*g->totalbytes; /* avoid GC steps */
- setobj2s(L, L->top, tm);
- setuvalue(L, L->top+1, udata);
- L->top += 2;
- luaD_call(L, L->top - 2, 0);
- L->allowhook = oldah; /* restore hooks */
- g->GCthreshold = oldt; /* restore threshold */
- }
-}
-
-
-/*
-** Call all GC tag methods
-*/
-void luaC_callGCTM (lua_State *L) {
- while (G(L)->tmudata)
- GCTM(L);
-}
-
-
-void luaC_freeall (lua_State *L) {
- global_State *g = G(L);
- int i;
- g->currentwhite = WHITEBITS | bitmask(SFIXEDBIT); /* mask to collect all elements */
- sweepwholelist(L, &g->rootgc);
- for (i = 0; i < g->strt.size; i++) /* free all string lists */
- sweepwholelist(L, &g->strt.hash[i]);
-}
-
-
-static void markmt (global_State *g) {
- int i;
- for (i=0; i<NUM_TAGS; i++)
- if (g->mt[i]) markobject(g, g->mt[i]);
-}
-
-
-/* mark root set */
-static void markroot (lua_State *L) {
- global_State *g = G(L);
- g->gray = NULL;
- g->grayagain = NULL;
- g->weak = NULL;
- markobject(g, g->mainthread);
- /* make global table be traversed before main stack */
- markvalue(g, gt(g->mainthread));
- markvalue(g, registry(L));
- markmt(g);
- g->gcstate = GCSpropagate;
-}
-
-
-static void remarkupvals (global_State *g) {
- UpVal *uv;
- for (uv = g->uvhead.u.l.next; uv != &g->uvhead; uv = uv->u.l.next) {
- lua_assert(uv->u.l.next->u.l.prev == uv && uv->u.l.prev->u.l.next == uv);
- if (isgray(obj2gco(uv)))
- markvalue(g, uv->v);
- }
-}
-
-
-static void atomic (lua_State *L) {
- global_State *g = G(L);
- size_t udsize; /* total size of userdata to be finalized */
- /* remark occasional upvalues of (maybe) dead threads */
- remarkupvals(g);
- /* traverse objects cautch by write barrier and by 'remarkupvals' */
- propagateall(g);
- /* remark weak tables */
- g->gray = g->weak;
- g->weak = NULL;
- lua_assert(!iswhite(obj2gco(g->mainthread)));
- markobject(g, L); /* mark running thread */
- markmt(g); /* mark basic metatables (again) */
- propagateall(g);
- /* remark gray again */
- g->gray = g->grayagain;
- g->grayagain = NULL;
- propagateall(g);
- udsize = luaC_separateudata(L, 0); /* separate userdata to be finalized */
- marktmu(g); /* mark `preserved' userdata */
- udsize += propagateall(g); /* remark, to propagate `preserveness' */
- cleartable(g->weak); /* remove collected objects from weak tables */
- /* flip current white */
- g->currentwhite = cast_byte(otherwhite(g));
- g->sweepstrgc = 0;
- g->sweepgc = &g->rootgc;
- g->gcstate = GCSsweepstring;
- g->estimate = g->totalbytes - udsize; /* first estimate */
-}
-
-
-static l_mem singlestep (lua_State *L) {
- global_State *g = G(L);
- /*lua_checkmemory(L);*/
- switch (g->gcstate) {
- case GCSpause: {
- markroot(L); /* start a new collection */
- return 0;
- }
- case GCSpropagate: {
- if (g->gray)
- return propagatemark(g);
- else { /* no more `gray' objects */
- atomic(L); /* finish mark phase */
- return 0;
- }
- }
- case GCSsweepstring: {
- lu_mem old = g->totalbytes;
- sweepwholelist(L, &g->strt.hash[g->sweepstrgc++]);
- if (g->sweepstrgc >= g->strt.size) /* nothing more to sweep? */
- g->gcstate = GCSsweep; /* end sweep-string phase */
- lua_assert(old >= g->totalbytes);
- g->estimate -= old - g->totalbytes;
- return GCSWEEPCOST;
- }
- case GCSsweep: {
- lu_mem old = g->totalbytes;
- g->sweepgc = sweeplist(L, g->sweepgc, GCSWEEPMAX);
- if (*g->sweepgc == NULL) { /* nothing more to sweep? */
- checkSizes(L);
- g->gcstate = GCSfinalize; /* end sweep phase */
- }
- lua_assert(old >= g->totalbytes);
- g->estimate -= old - g->totalbytes;
- return GCSWEEPMAX*GCSWEEPCOST;
- }
- case GCSfinalize: {
- if (g->tmudata) {
- GCTM(L);
- if (g->estimate > GCFINALIZECOST)
- g->estimate -= GCFINALIZECOST;
- return GCFINALIZECOST;
- }
- else {
- g->gcstate = GCSpause; /* end collection */
- g->gcdept = 0;
- return 0;
- }
- }
- default: lua_assert(0); return 0;
- }
-}
-
-
-void luaC_step (lua_State *L) {
- global_State *g = G(L);
- l_mem lim = (GCSTEPSIZE/100) * g->gcstepmul;
- if (lim == 0)
- lim = (MAX_LUMEM-1)/2; /* no limit */
- g->gcdept += g->totalbytes - g->GCthreshold;
- do {
- lim -= singlestep(L);
- if (g->gcstate == GCSpause)
- break;
- } while (lim > 0);
- if (g->gcstate != GCSpause) {
- if (g->gcdept < GCSTEPSIZE)
- g->GCthreshold = g->totalbytes + GCSTEPSIZE; /* - lim/g->gcstepmul;*/
- else {
- g->gcdept -= GCSTEPSIZE;
- g->GCthreshold = g->totalbytes;
- }
- }
- else {
- setthreshold(g);
- }
-}
-
-
-void luaC_fullgc (lua_State *L) {
- global_State *g = G(L);
- if (g->gcstate <= GCSpropagate) {
- /* reset sweep marks to sweep all elements (returning them to white) */
- g->sweepstrgc = 0;
- g->sweepgc = &g->rootgc;
- /* reset other collector lists */
- g->gray = NULL;
- g->grayagain = NULL;
- g->weak = NULL;
- g->gcstate = GCSsweepstring;
- }
- lua_assert(g->gcstate != GCSpause && g->gcstate != GCSpropagate);
- /* finish any pending sweep phase */
- while (g->gcstate != GCSfinalize) {
- lua_assert(g->gcstate == GCSsweepstring || g->gcstate == GCSsweep);
- singlestep(L);
- }
- markroot(L);
- while (g->gcstate != GCSpause) {
- singlestep(L);
- }
- setthreshold(g);
-}
-
-
-void luaC_barrierf (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 != GCSfinalize && g->gcstate != GCSpause);
- lua_assert(ttype(&o->gch) != LUA_TTABLE);
- /* must keep invariant? */
- if (g->gcstate == GCSpropagate)
- reallymarkobject(g, v); /* restore invariant */
- else /* don't mind */
- makewhite(g, o); /* mark as white just to avoid other barriers */
-}
-
-
-void luaC_barrierback (lua_State *L, Table *t) {
- global_State *g = G(L);
- GCObject *o = obj2gco(t);
- lua_assert(isblack(o) && !isdead(g, o));
- lua_assert(g->gcstate != GCSfinalize && g->gcstate != GCSpause);
- black2gray(o); /* make table gray (again) */
- t->gclist = g->grayagain;
- g->grayagain = o;
-}
-
-
-void luaC_link (lua_State *L, GCObject *o, lu_byte tt) {
- global_State *g = G(L);
- o->gch.next = g->rootgc;
- g->rootgc = o;
- o->gch.marked = luaC_white(g);
- o->gch.tt = tt;
-}
-
-
-void luaC_linkupval (lua_State *L, UpVal *uv) {
- global_State *g = G(L);
- GCObject *o = obj2gco(uv);
- o->gch.next = g->rootgc; /* link upvalue into `rootgc' list */
- g->rootgc = o;
- if (isgray(o)) {
- if (g->gcstate == GCSpropagate) {
- gray2black(o); /* closed upvalues need barrier */
- luaC_barrier(L, uv, uv->v);
- }
- else { /* sweep phase: sweep it (turning it into white) */
- makewhite(g, o);
- lua_assert(g->gcstate != GCSfinalize && g->gcstate != GCSpause);
- }
- }
-}
-
projects / ceph.git / blobdiff