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Upvalues collected like everything else (with mark-sweep) instead

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of reference count (simpler and better for generational mode)
This commit is contained in:
Roberto Ierusalimschy
2017-04-11 15:41:09 -03:00
parent 9569ad6b0d
commit a3d36fe283
9 changed files with 97 additions and 127 deletions
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89
lgc.c
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@@ -1,5 +1,5 @@
/*
** $Id: lgc.c,v 2.218 2017/04/06 13:08:56 roberto Exp roberto $
** $Id: lgc.c,v 2.219 2017/04/10 13:33:04 roberto Exp roberto $
** Garbage Collector
** See Copyright Notice in lua.h
*/
@@ -179,25 +179,11 @@ void luaC_barrierback_ (lua_State *L, Table *t) {
}
/*
** barrier for assignments to closed upvalues. Because upvalues are
** shared among closures, it is impossible to know the color of all
** closures pointing to it. So, we assume that the object being assigned
** must be marked.
*/
void luaC_upvalbarrier_ (lua_State *L, GCObject *o) {
global_State *g = G(L);
if (keepinvariant(g) && !isold(o)) {
markobject(g, o);
setage(o, G_OLD0);
}
}
void luaC_fix (lua_State *L, GCObject *o) {
global_State *g = G(L);
lua_assert(g->allgc == o); /* object must be 1st in 'allgc' list! */
white2gray(o); /* they will be gray forever */
setage(o, G_OLD); /* and old forever */
g->allgc = o->next; /* remove object from 'allgc' list */
o->next = g->fixedgc; /* link it to 'fixedgc' list */
g->fixedgc = o;
@@ -230,10 +216,11 @@ GCObject *luaC_newobj (lua_State *L, int tt, size_t sz) {
/*
** mark an object. Userdata, strings, and closed upvalues are visited
** 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.)
** upvalues are already linked in 'headuv' list. They are kept gray
** to avoid barriers, as their values will be revisited by the thread.)
*/
static void reallymarkobject (global_State *g, GCObject *o) {
reentry:
@@ -261,6 +248,14 @@ static void reallymarkobject (global_State *g, GCObject *o) {
}
break;
}
case LUA_TUPVAL: {
UpVal *uv = gco2upv(o);
g->GCmemtrav += sizeof(UpVal);
if (!upisopen(uv)) /* open upvalues are kept gray */
gray2black(o);
markvalue(g, uv->v); /* mark its content */
break;
}
case LUA_TLCL: {
linkgclist(gco2lcl(o), g->gray);
break;
@@ -324,10 +319,8 @@ static void remarkupvals (global_State *g) {
*p = thread->twups; /* remove thread from the list */
thread->twups = thread; /* mark that it is out of list */
for (uv = thread->openupval; uv != NULL; uv = uv->u.open.next) {
if (uv->u.open.touched) {
markvalue(g, uv->v); /* remark upvalue's value */
uv->u.open.touched = 0;
}
if (!iswhite(uv)) /* upvalue already visited? */
markvalue(g, uv->v); /* mark its value */
}
}
}
@@ -516,22 +509,15 @@ static lu_mem traverseCclosure (global_State *g, CClosure *cl) {
}
/*
** open upvalues point to values in a thread, so those values should
** be marked when the thread is traversed except in the atomic phase
** (because then the value cannot be changed by the thread and the
** thread may not be traversed again)
** Traverse a Lua closure, marking its prototype and its upvalues.
** (Both can be NULL while closure is being created.)
*/
static lu_mem traverseLclosure (global_State *g, LClosure *cl) {
int i;
markobjectN(g, cl->p); /* mark its prototype */
for (i = 0; i < cl->nupvalues; i++) { /* visit its upvalues */
UpVal *uv = cl->upvals[i];
if (uv != NULL) { /* can be NULL while closure is being built */
if (upisopen(uv) && g->gcstate != GCSatomic)
uv->u.open.touched = 1; /* can be marked in 'remarkupvals' */
else
markvalue(g, uv->v);
}
markobjectN(g, uv); /* mark upvalue */
}
return sizeLclosure(cl->nupvalues);
}
@@ -569,7 +555,6 @@ static lu_mem traversethread (global_State *g, lua_State *th) {
static void propagatemark (global_State *g) {
lu_mem size;
GCObject *o = g->gray;
lua_assert(ongraylist(o));
gray2black(o);
switch (o->tt) {
case LUA_TTABLE: {
@@ -683,26 +668,10 @@ static void clearvalues (global_State *g, GCObject *l, GCObject *f) {
}
/*
** Decrement the reference count of an upvalue. If it goes to zero and
** upvalue is closed, delete it.
*/
void luaC_upvdeccount (lua_State *L, UpVal *uv) {
lua_assert(uv->refcount > 0);
uv->refcount--;
if (uv->refcount == 0 && !upisopen(uv))
luaM_free(L, uv);
}
static void freeLclosure (lua_State *L, LClosure *cl) {
int i;
for (i = 0; i < cl->nupvalues; i++) {
UpVal *uv = cl->upvals[i];
if (uv)
luaC_upvdeccount(L, uv);
}
luaM_freemem(L, cl, sizeLclosure(cl->nupvalues));
static void freeupval (lua_State *L, UpVal *uv) {
if (upisopen(uv))
luaF_unlinkupval(uv);
luaM_free(L, uv);
}
@@ -711,8 +680,11 @@ static void freeobj (lua_State *L, GCObject *o) {
case LUA_TPROTO:
luaF_freeproto(L, gco2p(o));
break;
case LUA_TUPVAL:
freeupval(L, gco2upv(o));
break;
case LUA_TLCL:
freeLclosure(L, gco2lcl(o));
luaM_freemem(L, o, sizeLclosure(gco2lcl(o)->nupvalues));
break;
case LUA_TCCL:
luaM_freemem(L, o, sizeCclosure(gco2ccl(o)->nupvalues));
@@ -1144,14 +1116,14 @@ static void correctgraylists (global_State *g) {
/*
** Mark 'old1' objects when starting a new young collection. ('old1'
** tables are always black, threads are always gray.)
** Mark 'old1' objects when starting a new young collection. (Threads
** and open upvalues are always gray, and do not need to be marked.
** All other old objects are black.)
*/
static void markold (global_State *g, GCObject *from, GCObject *to) {
GCObject *p;
for (p = from; p != to; p = p->next) {
if (getage(p) == G_OLD1) {
lua_assert((p->tt == LUA_TTHREAD) ? isgray(p) : isblack(p));
if (isblack(p)) {
black2gray(p); /* should be '2white', but gray works too */
reallymarkobject(g, p);
@@ -1228,6 +1200,8 @@ static void entergen (lua_State *L, global_State *g) {
sweep2old(L, &g->tobefnz);
setage(g->mainthread, G_OLD);
finishgencycle(L, g);
g->gckind = KGC_GEN;
}
@@ -1282,6 +1256,7 @@ static void genstep (lua_State *L, global_State *g) {
youngcollection(L, g);
mem = gettotalbytes(g);
luaE_setdebt(g, -((mem / 100) * 20));
lua_checkmemory(L);
}