mirror of https://github.com/lua/lua
revamp of the GC pace control; more like 5.1: any X Kbytes allocated
makes the GC handle f(X) Kbytes of objects
This commit is contained in:
Roberto Ierusalimschy
parent
8d0e1ed52f
commit
2a66b34f72
213
lgc.c
213
lgc.c
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@ -1,5 +1,5 @@
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/*
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** $Id: lgc.c,v 2.121 2012/05/11 19:22:33 roberto Exp roberto $
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** $Id: lgc.c,v 2.122 2012/05/14 17:52:56 roberto Exp roberto $
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** Garbage Collector
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** See Copyright Notice in lua.h
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*/
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@ -25,33 +25,36 @@
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/* how much to allocate before next GC step */
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#define GCSTEPSIZE 1024
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#define GCSTEPSIZE (cast_int(256 * sizeof(void*)))
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/* cost of sweeping one element (half the size of a small object) */
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#define GCSWEEPCOST ((sizeof(TString) + 2) / 2)
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/* maximum number of elements to sweep in each single step */
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#define GCSWEEPMAX 40
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/* cost of sweeping one element */
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#define GCSWEEPCOST 1
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#define GCSWEEPMAX (cast_int((GCSTEPSIZE / GCSWEEPCOST) / 4))
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/* maximum number of finalizers to call in each GC step */
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#define GCFINALIZENUM 4
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/* cost of marking the root set */
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#define GCROOTCOST 10
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/* (arbitrary) cost of atomic step */
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#define GCATOMICCOST GCSTEPSIZE
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/* cost of atomic step */
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#define GCATOMICCOST 1000
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/* basic cost to traverse one object (to be added to the links the
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object may have) */
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#define TRAVCOST 5
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/*
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** macro to apply the "speed" of the garbage collector: the constant
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** 80 makes the standard 'stepmul' of 200 results in the GC handling
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** 80/200 = 1/2.5 = 0.4Kbytes for every 1Kb allocated.
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** (The computation tries to avoid overflows or underflows.)
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*/
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#define workrate(x,mul) \
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((x) < MAX_INT/80 ? ((x) * 80) / mul : ((x) / mul) * 80)
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/*
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** standard negative debt for GC; a reasonable "time" to wait before
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** starting a new cycle
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*/
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#define stddebt(g) (-cast(l_mem, gettotalbytes(g)/100) * g->gcpause)
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#define stddebtest(g,e) (-cast(l_mem, (e)/100) * g->gcpause)
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#define stddebt(g) stddebtest(g, gettotalbytes(g))
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/*
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@ -244,53 +247,57 @@ GCObject *luaC_newobj (lua_State *L, int tt, size_t sz, GCObject **list,
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** upvalues are already linked in 'headuv' list.)
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*/
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static void reallymarkobject (global_State *g, GCObject *o) {
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lu_mem size;
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white2gray(o);
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switch (gch(o)->tt) {
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case LUA_TSHRSTR:
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case LUA_TLNGSTR: {
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gray2black(o);
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return; /* nothing else to mark */
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size = sizestring(gco2ts(o));
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break; /* nothing else to mark; make it black */
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}
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case LUA_TUSERDATA: {
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Table *mt = gco2u(o)->metatable;
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markobject(g, mt);
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markobject(g, gco2u(o)->env);
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gray2black(o); /* all pointers marked */
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return;
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size = sizeudata(gco2u(o));
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break;
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}
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case LUA_TUPVAL: {
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UpVal *uv = gco2uv(o);
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markvalue(g, uv->v);
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if (uv->v == &uv->u.value) /* closed? (open upvalues remain gray) */
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gray2black(o); /* make it black */
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return;
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if (uv->v != &uv->u.value) /* open? */
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return; /* open upvalues remain gray */
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size = sizeof(UpVal);
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break;
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}
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case LUA_TLCL: {
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gco2lcl(o)->gclist = g->gray;
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g->gray = o;
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break;
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return;
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}
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case LUA_TCCL: {
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gco2ccl(o)->gclist = g->gray;
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g->gray = o;
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break;
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return;
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}
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case LUA_TTABLE: {
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linktable(gco2t(o), &g->gray);
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break;
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return;
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}
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case LUA_TTHREAD: {
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gco2th(o)->gclist = g->gray;
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g->gray = o;
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break;
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return;
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}
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case LUA_TPROTO: {
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gco2p(o)->gclist = g->gray;
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g->gray = o;
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break;
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return;
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}
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default: lua_assert(0);
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default: lua_assert(0); return;
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}
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gray2black(o);
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g->GCmemtrav += size;
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}
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@ -430,30 +437,26 @@ static void traversestrongtable (global_State *g, Table *h) {
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}
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static int traversetable (global_State *g, Table *h) {
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static lu_mem traversetable (global_State *g, Table *h) {
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char *weakkey, *weakvalue;
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const TValue *mode = gfasttm(g, h->metatable, TM_MODE);
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markobject(g, h->metatable);
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if (mode && ttisstring(mode)) { /* is there a weak mode? */
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int weakkey = (strchr(svalue(mode), 'k') != NULL);
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int weakvalue = (strchr(svalue(mode), 'v') != NULL);
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if (weakkey || weakvalue) { /* is really weak? */
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black2gray(obj2gco(h)); /* keep table gray */
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if (!weakkey) { /* strong keys? */
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traverseweakvalue(g, h);
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return TRAVCOST + sizenode(h);
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}
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else if (!weakvalue) { /* strong values? */
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traverseephemeron(g, h);
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return TRAVCOST + h->sizearray + sizenode(h);
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}
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else {
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linktable(h, &g->allweak); /* nothing to traverse now */
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return TRAVCOST;
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}
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} /* else go through */
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if (mode && ttisstring(mode) && /* is there a weak mode? */
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((weakkey = strchr(svalue(mode), 'k')),
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(weakvalue = strchr(svalue(mode), 'v')),
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(weakkey || weakvalue))) { /* is really weak? */
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black2gray(obj2gco(h)); /* keep table gray */
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if (!weakkey) /* strong keys? */
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traverseweakvalue(g, h);
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else if (!weakvalue) /* strong values? */
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traverseephemeron(g, h);
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else /* all weak */
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linktable(h, &g->allweak); /* nothing to traverse now */
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}
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traversestrongtable(g, h);
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return TRAVCOST + h->sizearray + (2 * sizenode(h));
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else /* not weak */
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traversestrongtable(g, h);
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return sizeof(Table) + sizeof(TValue) * h->sizearray +
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sizeof(Node) * sizenode(h);
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}
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@ -470,81 +473,92 @@ static int traverseproto (global_State *g, Proto *f) {
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markobject(g, f->p[i]);
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for (i = 0; i < f->sizelocvars; i++) /* mark local-variable names */
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markobject(g, f->locvars[i].varname);
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return TRAVCOST + f->sizek + f->sizeupvalues + f->sizep + f->sizelocvars;
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return sizeof(Proto) + sizeof(Instruction) * f->sizecode +
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sizeof(Proto *) * f->sizep +
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sizeof(TValue) * f->sizek +
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sizeof(int) * f->sizelineinfo +
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sizeof(LocVar) * f->sizelocvars +
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sizeof(Upvaldesc) * f->sizeupvalues;
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}
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static int traverseCclosure (global_State *g, CClosure *cl) {
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static lu_mem traverseCclosure (global_State *g, CClosure *cl) {
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int i;
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for (i = 0; i < cl->nupvalues; i++) /* mark its upvalues */
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markvalue(g, &cl->upvalue[i]);
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return TRAVCOST + cl->nupvalues;
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return sizeCclosure(cl->nupvalues);
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}
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static int traverseLclosure (global_State *g, LClosure *cl) {
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static lu_mem traverseLclosure (global_State *g, LClosure *cl) {
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int i;
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markobject(g, cl->p); /* mark its prototype */
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for (i = 0; i < cl->nupvalues; i++) /* mark its upvalues */
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markobject(g, cl->upvals[i]);
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return TRAVCOST + cl->nupvalues;
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return sizeLclosure(cl->nupvalues);
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}
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static int traversestack (global_State *g, lua_State *L) {
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StkId o = L->stack;
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static lu_mem traversestack (global_State *g, lua_State *th) {
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StkId o = th->stack;
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if (o == NULL)
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return 1; /* stack not completely built yet */
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for (; o < L->top; o++)
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for (; o < th->top; o++)
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markvalue(g, o);
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if (g->gcstate == GCSatomic) { /* final traversal? */
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StkId lim = L->stack + L->stacksize; /* real end of stack */
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StkId lim = th->stack + th->stacksize; /* real end of stack */
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for (; o < lim; o++) /* clear not-marked stack slice */
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setnilvalue(o);
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}
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return TRAVCOST + cast_int(o - L->stack);
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return sizeof(lua_State) + sizeof(TValue) * th->stacksize;
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}
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/*
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** traverse one gray object, turning it to black (except for threads,
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** which are always gray).
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** Returns number of values traversed.
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*/
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static int propagatemark (global_State *g) {
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static void propagatemark (global_State *g) {
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lu_mem size;
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GCObject *o = g->gray;
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lua_assert(isgray(o));
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gray2black(o);
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switch (gch(o)->tt) {
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case LUA_TTABLE: {
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Table *h = gco2t(o);
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g->gray = h->gclist;
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return traversetable(g, h);
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g->gray = h->gclist; /* remove from 'gray' list */
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size = traversetable(g, h);
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break;
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}
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case LUA_TLCL: {
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LClosure *cl = gco2lcl(o);
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g->gray = cl->gclist;
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return traverseLclosure(g, cl);
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g->gray = cl->gclist; /* remove from 'gray' list */
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size = traverseLclosure(g, cl);
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break;
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}
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case LUA_TCCL: {
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CClosure *cl = gco2ccl(o);
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g->gray = cl->gclist;
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return traverseCclosure(g, cl);
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g->gray = cl->gclist; /* remove from 'gray' list */
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size = traverseCclosure(g, cl);
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break;
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}
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case LUA_TTHREAD: {
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lua_State *th = gco2th(o);
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g->gray = th->gclist;
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g->gray = th->gclist; /* remove from 'gray' list */
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th->gclist = g->grayagain;
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g->grayagain = o;
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g->grayagain = o; /* insert into 'grayagain' list */
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black2gray(o);
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return traversestack(g, th);
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size = traversestack(g, th);
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break;
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}
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case LUA_TPROTO: {
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Proto *p = gco2p(o);
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g->gray = p->gclist;
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return traverseproto(g, p);
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g->gray = p->gclist; /* remove from 'gray' list */
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size = traverseproto(g, p);
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break;
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}
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default: lua_assert(0); return 0;
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default: lua_assert(0); return;
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}
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g->GCmemtrav += size;
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}
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@ -706,7 +720,6 @@ static GCObject **sweeplist (lua_State *L, GCObject **p, lu_mem count) {
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int ow = otherwhite(g);
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int toclear, toset; /* bits to clear and to set in all live objects */
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int tostop; /* stop sweep when this is true */
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l_mem debt = g->GCdebt; /* current debt */
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if (isgenerational(g)) { /* generational mode? */
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toclear = ~0; /* clear nothing */
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toset = bitmask(OLDBIT); /* set the old bit of all surviving objects */
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@ -737,7 +750,6 @@ static GCObject **sweeplist (lua_State *L, GCObject **p, lu_mem count) {
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p = &gch(curr)->next; /* go to next element */
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}
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}
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luaE_setdebt(g, debt); /* sweeping should not change debt */
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return p;
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}
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@ -960,37 +972,42 @@ static void atomic (lua_State *L) {
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}
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static l_mem singlestep (lua_State *L) {
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static lu_mem singlestep (lua_State *L) {
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global_State *g = G(L);
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switch (g->gcstate) {
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case GCSpause: {
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g->GCmemtrav = 0; /* start to count memory traversed */
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if (!isgenerational(g))
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markroot(g); /* start a new collection */
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/* in any case, root must be marked */
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/* in any case, root must be marked at this point */
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lua_assert(!iswhite(obj2gco(g->mainthread))
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&& !iswhite(gcvalue(&g->l_registry)));
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g->gcstate = GCSpropagate;
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return GCROOTCOST;
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return g->GCmemtrav;
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}
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case GCSpropagate: {
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if (g->gray)
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return propagatemark(g);
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if (g->gray) {
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lu_mem oldtrav = g->GCmemtrav;
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propagatemark(g);
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return g->GCmemtrav - oldtrav; /* memory traversed in this step */
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}
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else { /* no more `gray' objects */
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g->gcstate = GCSatomic; /* finish mark phase */
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g->estimate = g->GCmemtrav; /* save what was counted */
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atomic(L);
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return GCATOMICCOST;
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}
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}
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case GCSsweepstring: {
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if (g->sweepstrgc < g->strt.size) {
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sweepwholelist(L, &g->strt.hash[g->sweepstrgc++]);
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return GCSWEEPCOST;
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}
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else { /* no more strings to sweep */
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int i;
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for (i = 0; i < GCSWEEPMAX && g->sweepstrgc + i < g->strt.size; i++)
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sweepwholelist(L, &g->strt.hash[g->sweepstrgc + i]);
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g->sweepstrgc += i;
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if (g->sweepstrgc >= g->strt.size) { /* no more strings to sweep? */
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g->sweepgc = &g->finobj; /* prepare to sweep finalizable objects */
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g->gcstate = GCSsweepudata;
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return 0;
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}
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return i * GCSWEEPCOST;
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}
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case GCSsweepudata: {
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if (*g->sweepgc) {
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@ -1000,7 +1017,7 @@ static l_mem singlestep (lua_State *L) {
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else {
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g->sweepgc = &g->allgc; /* go to next phase */
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g->gcstate = GCSsweep;
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return GCSWEEPCOST;
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return 0;
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}
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}
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case GCSsweep: {
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@ -1051,14 +1068,17 @@ static void generationalcollection (lua_State *L) {
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static void step (lua_State *L) {
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global_State *g = G(L);
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l_mem lim = g->gcstepmul; /* how much to work */
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l_mem debt = g->GCdebt;
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int stepmul = g->gcstepmul;
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if (stepmul <= 0) stepmul = 1;
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do { /* always perform at least one single step */
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lim -= singlestep(L);
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} while (lim > 0 && g->gcstate != GCSpause);
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if (g->gcstate != GCSpause)
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luaE_setdebt(g, g->GCdebt - GCSTEPSIZE);
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else
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luaE_setdebt(g, stddebt(g));
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lu_mem work = singlestep(L); /* do some work */
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work = workrate(work, stepmul); /* apply work rate */
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debt -= work;
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} while (debt > -GCSTEPSIZE && g->gcstate != GCSpause);
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if (g->gcstate == GCSpause)
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debt = stddebtest(g, g->estimate); /* pause until next cycle */
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luaE_setdebt(g, debt);
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}
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@ -1070,8 +1090,9 @@ void luaC_step (lua_State *L) {
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int i;
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if (isgenerational(g)) generationalcollection(L);
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else step(L);
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for (i = 0; i < GCFINALIZENUM && g->tobefnz; i++)
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GCTM(L, 1); /* Call a few pending finalizers */
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/* run a few finalizers (or all of them at the end of a collect cycle) */
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for (i = 0; g->tobefnz && (i < GCFINALIZENUM || g->gcstate == GCSpause); i++)
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GCTM(L, 1); /* call one finalizer */
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}
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4
lstate.h
4
lstate.h
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@ -1,5 +1,5 @@
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/*
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** $Id: lstate.h,v 2.76 2012/01/25 21:05:40 roberto Exp roberto $
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** $Id: lstate.h,v 2.77 2012/02/01 21:57:15 roberto Exp roberto $
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** Global State
|
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** See Copyright Notice in lua.h
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*/
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@ -113,7 +113,9 @@ typedef struct global_State {
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void *ud; /* auxiliary data to `frealloc' */
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lu_mem totalbytes; /* number of bytes currently allocated - GCdebt */
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l_mem GCdebt; /* bytes allocated not yet compensated by the collector */
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lu_mem GCmemtrav; /* memory traversed by the GC */
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lu_mem lastmajormem; /* memory in use after last major collection */
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lu_mem estimate;
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stringtable strt; /* hash table for strings */
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TValue l_registry;
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unsigned int seed; /* randomized seed for hashes */
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Reference in New Issue