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;
}
/*
** 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;
}
}
/*
** 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);
}
}
/*
** 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 (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 */
linkgclist(th, g->grayagain); /* insert into 'grayagain' list */
black2gray(o);
size = traversethread(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 lu_mem traversetable (global_State *g, Table *h) {
const char *weakkey, *weakvalue;
const TValue *mode = gfasttm(g, h->metatable, TM_MODE);
markobjectN(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(h); /* keep table gray */
if (!weakkey) /* strong keys? */
traverseweakvalue(g, h);
else if (!weakvalue) /* strong values? */
traverseephemeron(g, h);
else /* all weak */
linkgclist(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));
}
/*
** barrier that moves collector backward, that is, mark the black object
** pointing to a white object as gray again.
*/
void luaC_barrierback_ (lua_State *L, Table *t) {
global_State *g = G(L);
lua_assert(isblack(t) && !isdead(g, t));
black2gray(t); /* make table gray (again) */
linkgclist(t, g->grayagain);
}