userdata with finalizers are kept in a separated list

lapi.c

@@ -1,12 +1,10 @@
 /*
-** $Id: lapi.c,v 2.64 2008/02/12 13:34:12 roberto Exp roberto $
+** $Id: lapi.c,v 2.65 2008/02/14 16:02:58 roberto Exp roberto $
 ** Lua API
 ** See Copyright Notice in lua.h
 */
 
 
-#include <assert.h>
-#include <math.h>
 #include <stdarg.h>
 #include <string.h>
 
@@ -698,8 +696,10 @@ LUA_API int lua_setmetatable (lua_State *L, int objindex) {
     }
     case LUA_TUSERDATA: {
       uvalue(obj)->metatable = mt;
-      if (mt)
+      if (mt) {
         luaC_objbarrier(L, rawuvalue(obj), mt);
+        luaC_checkfinalizer(L, rawuvalue(obj));
+      }
       break;
     }
     default: {

lgc.c

@@ -1,5 +1,5 @@
 /*
-** $Id: lgc.c,v 2.42 2007/10/31 15:41:19 roberto Exp roberto $
+** $Id: lgc.c,v 2.43 2008/02/11 15:46:03 roberto Exp roberto $
 ** Garbage Collector
 ** See Copyright Notice in lua.h
 */
@@ -29,24 +29,22 @@
 #define GCFINALIZECOST	100
 
 
-#define maskmarks	cast_byte(~(bitmask(BLACKBIT)|WHITEBITS))
+#define maskcolors	cast_byte(~(bitmask(BLACKBIT)|WHITEBITS))
 
 #define makewhite(g,x)	\
-   ((x)->gch.marked = cast_byte(((x)->gch.marked & maskmarks) | luaC_white(g)))
+ (gch(x)->marked = cast_byte((gch(x)->marked & maskcolors) | luaC_white(g)))
 
-#define white2gray(x)	reset2bits((x)->gch.marked, WHITE0BIT, WHITE1BIT)
-#define black2gray(x)	resetbit((x)->gch.marked, BLACKBIT)
+#define white2gray(x)	resetbits(gch(x)->marked, WHITEBITS)
+#define black2gray(x)	resetbit(gch(x)->marked, BLACKBIT)
 
-#define stringmark(s)	reset2bits((s)->tsv.marked, WHITE0BIT, WHITE1BIT)
+#define stringmark(s)	resetbits((s)->tsv.marked, WHITEBITS)
 
 
 #define isfinalized(u)		testbit((u)->marked, FINALIZEDBIT)
-#define markfinalized(u)	l_setbit((u)->marked, FINALIZEDBIT)
-
 
 
 #define markvalue(g,o) { checkconsistency(o); \
-  if (iscollectable(o) && iswhite(gcvalue(o))) reallymarkobject(g,gcvalue(o)); }
+  if (valiswhite(o)) reallymarkobject(g,gcvalue(o)); }
 
 #define markobject(g,t) { if ((t) && iswhite(obj2gco(t))) \
 		reallymarkobject(g, obj2gco(t)); }
@@ -89,7 +87,7 @@ static int iscleared (const TValue *o, int iskey) {
 static void reallymarkobject (global_State *g, GCObject *o) {
   lua_assert(iswhite(o) && !isdead(g, o));
   white2gray(o);
-  switch (o->gch.tt) {
+  switch (gch(o)->tt) {
     case LUA_TSTRING: {
       return;
     }
@@ -113,7 +111,7 @@ static void reallymarkobject (global_State *g, GCObject *o) {
       break;
     }
     case LUA_TTABLE: {
-      linktable(gco2h(o), &g->gray);
+      linktable(gco2t(o), &g->gray);
       break;
     }
     case LUA_TTHREAD: {
@@ -131,42 +129,30 @@ static void reallymarkobject (global_State *g, GCObject *o) {
 }
 
 
-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' */
+/* move 'dead' udata that need finalization to list 'tobefnz' */
 size_t luaC_separateudata (lua_State *L, int all) {
   global_State *g = G(L);
   size_t deadmem = 0;
-  GCObject **p = &g->mainthread->next;
+  GCObject **p = &g->tmudata;
   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 */
+    lua_assert(ttisuserdata(gch(curr)) && !isfinalized(gco2u(curr)));
+    lua_assert(testbit(gch(curr)->marked, SEPARATED));
+    if (all) makewhite(g, curr);  /* if 'all', collect all objects */
+    if (!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 */
+      reallymarkobject(g, curr);  /* won't be collected now */
       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 */
+      *p = gch(curr)->next;  /* remove 'curr' from 'tmudata' list */
+      /* link 'curr' at the end of 'tobefnz' list */
+      if (g->tobefnz == NULL)  /* list is empty? */
+        g->tobefnz = gch(curr)->next = curr;  /* creates a circular list */
       else {
-        curr->gch.next = g->tmudata->gch.next;
-        g->tmudata->gch.next = curr;
-        g->tmudata = curr;
+        gch(curr)->next = gch(g->tobefnz)->next;
+        gch(g->tobefnz)->next = curr;
+        g->tobefnz = curr;
       }
     }
   }
@@ -195,7 +181,7 @@ static int traverseephemeron (global_State *g, Table *h) {
   int hasclears = 0;
   int i = h->sizearray;
   while (i--) {  /* mark array part (numeric keys are 'strong') */
-    if (iscollectable(&h->array[i]) && iswhite(gcvalue(&h->array[i]))) {
+    if (valiswhite(&h->array[i])) {
       marked = 1;
       reallymarkobject(g, gcvalue(&h->array[i]));
     }
@@ -206,7 +192,7 @@ static int traverseephemeron (global_State *g, Table *h) {
     lua_assert(ttype(gkey(n)) != LUA_TDEADKEY || ttisnil(gval(n)));
     if (ttisnil(gval(n)))  /* entry is empty? */
       removeentry(n);  /* remove it */
-    else if (iscollectable(gval(n)) && iswhite(gcvalue(gval(n)))) {
+    else if (valiswhite(gval(n))) {
       /* value is not marked yet */
       if (iscleared(key2tval(n), 1))  /* key is not marked (yet)? */
         hasclears = 1;  /* may have to propagate mark from key to value */
@@ -256,10 +242,8 @@ static void traversetable (global_State *g, Table *h) {
         traverseweakvalue(g, h);
       else if (!weakvalue)  /* strong values? */
         traverseephemeron(g, h);
-      else {
-        lua_assert(weakkey && weakvalue);  /* nothing to traverse now */
-        linktable(h, &g->allweak);
-      }
+      else
+        linktable(h, &g->allweak);  /* nothing to traverse now */
       return;
     }  /* else go through */
   }
@@ -350,9 +334,9 @@ static l_mem propagatemark (global_State *g) {
   GCObject *o = g->gray;
   lua_assert(isgray(o));
   gray2black(o);
-  switch (o->gch.tt) {
+  switch (gch(o)->tt) {
     case LUA_TTABLE: {
-      Table *h = gco2h(o);
+      Table *h = gco2t(o);
       g->gray = h->gclist;
       traversetable(g, h);
       return sizeof(Table) + sizeof(TValue) * h->sizearray +
@@ -406,8 +390,8 @@ static void convergeephemerons (global_State *g) {
     g->ephemeron = NULL;
     changed = 0;
     while ((w = next) != NULL) {
-      next = gco2h(w)->gclist;
-      if (traverseephemeron(g, gco2h(w))) {
+      next = gco2t(w)->gclist;
+      if (traverseephemeron(g, gco2t(w))) {
         changed = 1;
         propagateall(g);
       }
@@ -422,7 +406,7 @@ static void convergeephemerons (global_State *g) {
 */
 static void cleartable (GCObject *l) {
   while (l) {
-    Table *h = gco2h(l);
+    Table *h = gco2t(l);
     int i = h->sizearray;
     while (i--) {
       TValue *o = &h->array[i];
@@ -444,25 +428,18 @@ static void cleartable (GCObject *l) {
 
 
 static void freeobj (lua_State *L, GCObject *o) {
-  switch (o->gch.tt) {
+  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, gco2h(o)); break;
-    case LUA_TTHREAD: {
-      lua_assert(gco2th(o) != L && gco2th(o) != G(L)->mainthread);
-      luaE_freethread(L, gco2th(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;
     }
-    case LUA_TUSERDATA: {
-      luaM_freemem(L, o, sizeudata(gco2u(o)));
-      break;
-    }
     default: lua_assert(0);
   }
 }
@@ -477,18 +454,16 @@ static GCObject **sweeplist (lua_State *L, GCObject **p, lu_mem count) {
   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 */
+    if (ttisthread(gch(curr)))  /* 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));
+    if ((gch(curr)->marked ^ WHITEBITS) & deadmask) {  /* not dead? */
+      lua_assert(!isdead(g, curr) || testbit(gch(curr)->marked, FIXEDBIT));
       makewhite(g, curr);  /* make it white (for next cycle) */
-      p = &curr->gch.next;
+      p = &gch(curr)->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 */
+      *p = gch(curr)->next;  /* remove 'curr' from list */
       freeobj(L, curr);
     }
   }
@@ -496,6 +471,15 @@ static GCObject **sweeplist (lua_State *L, GCObject **p, lu_mem count) {
 }
 
 
+static GCObject **unmarklist (global_State *g, GCObject **p, lu_mem count) {
+  for (; *p != NULL && count-- > 0; p = &gch(*p)->next) {
+     lua_assert(ttisuserdata(gch(*p)) && !isdead(g, *p));
+    makewhite(g, *p);
+  }
+  return p;
+}
+
+
 static void checkSizes (lua_State *L) {
   global_State *g = G(L);
   if (g->strt.nuse < cast(lu_int32, g->strt.size))
@@ -505,15 +489,16 @@ static void checkSizes (lua_State *L) {
 
 
 static Udata *udata2finalize (global_State *g) {
-  GCObject *o = g->tmudata->gch.next;  /* get first element */
+  GCObject *o = gch(g->tobefnz)->next;  /* get first element */
   Udata *udata = rawgco2u(o);
-  /* remove udata from `tmudata' */
-  if (o == g->tmudata)  /* last element? */
-    g->tmudata = NULL;
+  /* remove udata from `tobefnz' */
+  if (o == g->tobefnz)  /* last element? */
+    g->tobefnz = NULL;
   else
-    g->tmudata->gch.next = udata->uv.next;
+    gch(g->tobefnz)->next = udata->uv.next;
   udata->uv.next = g->mainthread->next;  /* return it to `root' list */
   g->mainthread->next = o;
+  resetbit(udata->uv.marked, SEPARATED);  /* mark it as such */
   makewhite(g, o);
   return udata;
 }
@@ -522,8 +507,8 @@ static Udata *udata2finalize (global_State *g) {
 static void GCTM (lua_State *L) {
   global_State *g = G(L);
   Udata *udata = udata2finalize(g);
-  const TValue *tm = fasttm(L, udata->uv.metatable, TM_GC);
-  if (tm != NULL) {
+  const TValue *tm = gfasttm(g, udata->uv.metatable, TM_GC);
+  if (tm != NULL && ttisfunction(tm)) {
     lu_byte oldah = L->allowhook;
     lu_mem oldt = g->GCthreshold;
     L->allowhook = 0;  /* stop debug hooks during GC tag method */
@@ -543,15 +528,15 @@ static void GCTM (lua_State *L) {
 */
 void luaC_callGCTM (lua_State *L) {
   global_State *g = G(L);
-  GCObject *last = g->tmudata;
+  GCObject *last = g->tobefnz;
   GCObject *curr;
   if (last == NULL) return;  /* empty list? */
   do {
-    curr = g->tmudata->gch.next;  /* element to be collected */
+    curr = gch(g->tobefnz)->next;  /* element to be collected */
     GCTM(L);
   } while (curr != last);  /* go only until original last */
   /* do not finalize new udata created during previous finalizations  */
-  while (g->tmudata)
+  while (g->tobefnz)
     udata2finalize(g);  /* simply remove them from list */
 }
 
@@ -559,10 +544,16 @@ void luaC_callGCTM (lua_State *L) {
 void luaC_freeall (lua_State *L) {
   global_State *g = G(L);
   int i;
-  g->currentwhite = WHITEBITS | bitmask(SFIXEDBIT);  /* mask to collect all elements */
+  lua_assert(g->tobefnz == NULL);
+  /* mask to collect all elements */
+  g->currentwhite = WHITEBITS | bitmask(SFIXEDBIT);
   sweepwholelist(L, &g->rootgc);
+  lua_assert(g->rootgc == obj2gco(L));
+  sweepwholelist(L, &g->tmudata);
+  lua_assert(g->tmudata == NULL);
   for (i = 0; i < g->strt.size; i++)  /* free all string lists */
     sweepwholelist(L, &g->strt.hash[i]);
+  lua_assert(g->strt.nuse == 0);
 }
 
 
@@ -573,6 +564,20 @@ static void markmt (global_State *g) {
 }
 
 
+static void markbeingfnz (global_State *g) {
+  GCObject *u = g->tobefnz;
+  if (u) {
+    do {
+      u = gch(u)->next;
+      lua_assert(testbit(gch(u)->marked, SEPARATED));
+      lua_assert(!iswhite(u));  /* must be marked, if left from previous GC */
+      makewhite(g, u);
+      reallymarkobject(g, u);
+    } while (u != g->tobefnz);
+  }
+}
+
+
 /* mark root set */
 static void markroot (lua_State *L) {
   global_State *g = G(L);
@@ -584,6 +589,7 @@ static void markroot (lua_State *L) {
   markvalue(g, gt(g->mainthread));
   markvalue(g, registry(L));
   markmt(g);
+  markbeingfnz(g);  /* mark any finalizing userdata left from previous cycle */
   g->gcstate = GCSpropagate;
 }
 
@@ -598,6 +604,14 @@ static void remarkupvals (global_State *g) {
 }
 
 
+static void marklistofgrays (global_State *g, GCObject **l) {
+  lua_assert(g->gray == NULL);  /* no grays left */
+  g->gray = *l;  /* now 'l' is new gray list */
+  *l = NULL;
+  propagateall(g);
+}
+
+
 static void atomic (lua_State *L) {
   global_State *g = G(L);
   size_t udsize;  /* total size of userdata to be finalized */
@@ -612,17 +626,10 @@ static void atomic (lua_State *L) {
   markobject(g, L);  /* mark running thread */
   markmt(g);  /* mark basic metatables (again) */
   propagateall(g);
-  /* remark ephemeron tables */
-  g->gray = g->ephemeron;
-  g->ephemeron = NULL;
-  propagateall(g);
-  /* remark gray again */
-  g->gray = g->grayagain;
-  g->grayagain = NULL;
-  propagateall(g);
+  marklistofgrays(g, &g->ephemeron);  /* remark ephemeron tables */
+  marklistofgrays(g, &g->grayagain);  /* remark gray again */
   convergeephemerons(g);
   udsize = luaC_separateudata(L, 0);  /* separate userdata to be finalized */
-  marktmu(g);  /* mark `preserved' userdata */
   udsize += propagateall(g);  /* remark, to propagate `preserveness' */
   convergeephemerons(g);
   /* remove collected objects from weak tables */
@@ -632,7 +639,6 @@ static void atomic (lua_State *L) {
   /* 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 */
 }
@@ -660,10 +666,20 @@ static l_mem singlestep (lua_State *L) {
     }
     case GCSsweepstring: {
       correctestimate(g, sweepwholelist(L, &g->strt.hash[g->sweepstrgc++]));
-      if (g->sweepstrgc >= g->strt.size)  /* nothing more to sweep? */
-        g->gcstate = GCSsweep;  /* end sweep-string phase */
+      if (g->sweepstrgc >= g->strt.size) {  /* nothing more to sweep? */
+        g->sweepgc = &g->tmudata;
+        g->gcstate = GCSsweeptmu;  /* end sweep-string phase */
+      }
       return GCSWEEPCOST;
     }
+    case GCSsweeptmu: {
+      g->sweepgc = unmarklist(g, g->sweepgc, GCSWEEPMAX);
+      if (*g->sweepgc == NULL) {  /* nothing more to sweep? */
+        g->sweepgc = &g->rootgc;
+        g->gcstate = GCSsweep;  /* sweep all other objects */
+      }
+      return GCSWEEPMAX*GCSWEEPCOST;
+    }
     case GCSsweep: {
       correctestimate(g, g->sweepgc = sweeplist(L, g->sweepgc, GCSWEEPMAX));
       if (*g->sweepgc == NULL)  /* nothing more to sweep? */
@@ -671,7 +687,7 @@ static l_mem singlestep (lua_State *L) {
       return GCSWEEPMAX*GCSWEEPCOST;
     }
     case GCSfinalize: {
-      if (g->tmudata) {
+      if (g->tobefnz) {
         GCTM(L);
         if (g->estimate > GCFINALIZECOST)
           g->estimate -= GCFINALIZECOST;
@@ -721,19 +737,17 @@ void luaC_fullgc (lua_State *L, int isemergency) {
   lua_assert(g->gckind == KGC_NORMAL);
   g->gckind = isemergency ? KGC_EMERGENCY : KGC_FORCED;
   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 = g->ephemeron = g->allweak = NULL;
+    g->sweepstrgc = 0;
     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);
+    lua_assert(issweep(g));
     singlestep(L);
   }
   markroot(L);
@@ -753,7 +767,7 @@ 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);
+  lua_assert(ttype(gch(o)) != LUA_TTABLE);
   /* must keep invariant? */
   if (g->gcstate == GCSpropagate)
     reallymarkobject(g, v);  /* restore invariant */
@@ -775,17 +789,17 @@ void luaC_barrierback (lua_State *L, Table *t) {
 
 void luaC_link (lua_State *L, GCObject *o, lu_byte tt) {
   global_State *g = G(L);
-  o->gch.next = g->rootgc;
+  gch(o)->marked = luaC_white(g);
+  gch(o)->tt = tt;
+  gch(o)->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 */
+  gch(o)->next = g->rootgc;  /* link upvalue into `rootgc' list */
   g->rootgc = o;
   if (isgray(o)) {
     if (g->gcstate == GCSpropagate) {
@@ -799,3 +813,22 @@ void luaC_linkupval (lua_State *L, UpVal *uv) {
   }
 }
 
+
+void luaC_checkfinalizer (lua_State *L, Udata *u) {
+  global_State *g = G(L);
+  if (testbit(u->uv.marked, SEPARATED) || /* userdata is already separated... */
+      isfinalized(&u->uv) ||                        /* ... or is finalized... */
+      gfasttm(g, u->uv.metatable, TM_GC) == NULL)  /* or has no finalization? */
+    return;  /* nothing to be done */
+  else {  /* move 'u' from root list to tobefnz list */
+    GCObject **p;
+    for (p = &g->rootgc; *p != obj2gco(u); p = &gch(*p)->next)
+      lua_assert(*p != NULL);  /* 'u' must be in this list */
+    *p = u->uv.next;  /* remove 'u' from root list */
+    u->uv.next = g->tmudata;  /* link it in tobefnz list */
+    g->tmudata = obj2gco(u);
+    l_setbit(u->uv.marked, SEPARATED);  /* mark it as such */
+  }
+}
+
+

lgc.h

@@ -1,5 +1,5 @@
 /*
-** $Id: lgc.h,v 2.16 2006/07/11 15:53:29 roberto Exp roberto $
+** $Id: lgc.h,v 2.17 2007/10/29 16:51:20 roberto Exp roberto $
 ** Garbage Collector
 ** See Copyright Notice in lua.h
 */
@@ -17,8 +17,13 @@
 #define GCSpause	0
 #define GCSpropagate	1
 #define GCSsweepstring	2
-#define GCSsweep	3
-#define GCSfinalize	4
+#define GCSsweeptmu	3
+#define GCSsweep	4
+#define GCSfinalize	5
+
+
+#define issweep(g) \
+	(GCSsweepstring <= (g)->gcstate && (g)->gcstate <= GCSsweep)
 
 
 /*
@@ -34,7 +39,6 @@
 #define testbit(x,b)	testbits(x, bitmask(b))
 #define set2bits(x,b1,b2)	setbits(x, (bit2mask(b1, b2)))
 #define reset2bits(x,b1,b2)	resetbits(x, (bit2mask(b1, b2)))
-#define test2bits(x,b1,b2)	testbits(x, (bit2mask(b1, b2)))
 
 
 
@@ -44,6 +48,7 @@
 ** bit 1 - object is white (type 1)
 ** bit 2 - object is black
 ** bit 3 - for userdata: has been finalized
+** bit 4 - for userdata: it's not in rootgc list (it's in tmudata or tobefnz)
 ** bit 5 - object is fixed (should not be collected)
 ** bit 6 - object is "super" fixed (only the main thread)
 */
@@ -53,12 +58,13 @@
 #define WHITE1BIT	1
 #define BLACKBIT	2
 #define FINALIZEDBIT	3
+#define SEPARATED	4
 #define FIXEDBIT	5
 #define SFIXEDBIT	6
 #define WHITEBITS	bit2mask(WHITE0BIT, WHITE1BIT)
 
 
-#define iswhite(x)      test2bits((x)->gch.marked, WHITE0BIT, WHITE1BIT)
+#define iswhite(x)      testbits((x)->gch.marked, WHITEBITS)
 #define isblack(x)      testbit((x)->gch.marked, BLACKBIT)
 #define isgray(x)	(!isblack(x) && !iswhite(x))
 
@@ -101,6 +107,7 @@ LUAI_FUNC void luaC_link (lua_State *L, GCObject *o, lu_byte tt);
 LUAI_FUNC void luaC_linkupval (lua_State *L, UpVal *uv);
 LUAI_FUNC void luaC_barrierf (lua_State *L, GCObject *o, GCObject *v);
 LUAI_FUNC void luaC_barrierback (lua_State *L, Table *t);
+LUAI_FUNC void luaC_checkfinalizer (lua_State *L, Udata *u);
 
 
 #endif

lstate.c

@@ -1,5 +1,5 @@
 /*
-** $Id: lstate.c,v 2.42 2007/10/31 15:41:19 roberto Exp roberto $
+** $Id: lstate.c,v 2.43 2008/02/11 15:45:30 roberto Exp roberto $
 ** Global State
 ** See Copyright Notice in lua.h
 */
@@ -107,8 +107,6 @@ static void close_state (lua_State *L) {
   global_State *g = G(L);
   luaF_close(L, L->stack);  /* close all upvalues for this thread */
   luaC_freeall(L);  /* collect all objects */
-  lua_assert(g->rootgc == obj2gco(L));
-  lua_assert(g->strt.nuse == 0);
   luaM_freearray(L, G(L)->strt.hash, G(L)->strt.size, TString *);
   luaZ_freebuffer(L, &g->buff);
   freestack(L, L);
@@ -183,7 +181,7 @@ LUA_API lua_State *lua_newstate (lua_Alloc f, void *ud) {
   g->gray = NULL;
   g->grayagain = NULL;
   g->weak = g->ephemeron = g->allweak = NULL;
-  g->tmudata = NULL;
+  g->tmudata = g->tobefnz = NULL;
   g->totalbytes = sizeof(LG);
   g->gcpause = LUAI_GCPAUSE;
   g->gcstepmul = LUAI_GCMUL;
@@ -210,14 +208,15 @@ LUA_API void lua_close (lua_State *L) {
   L = G(L)->mainthread;  /* only the main thread can be closed */
   lua_lock(L);
   luaF_close(L, L->stack);  /* close all upvalues for this thread */
-  luaC_separateudata(L, 1);  /* separate udata that have GC metamethods */
+  luaC_separateudata(L, 1);  /* separate all udata with GC metamethods */
+  lua_assert(G(L)->tmudata == NULL);
   L->errfunc = 0;  /* no error function during GC metamethods */
   do {  /* repeat until no more errors */
     L->ci = L->base_ci;
     L->base = L->top = L->ci->base;
     G(L)->nCcalls = 0;
   } while (luaD_rawrunprotected(L, callallgcTM, NULL) != LUA_OK);
-  lua_assert(G(L)->tmudata == NULL);
+  lua_assert(G(L)->tobefnz == NULL);
   luai_userstateclose(L);
   close_state(L);
 }

lstate.h

@@ -1,5 +1,5 @@
 /*
-** $Id: lstate.h,v 2.30 2007/10/31 15:41:19 roberto Exp roberto $
+** $Id: lstate.h,v 2.31 2008/02/11 15:45:30 roberto Exp roberto $
 ** Global State
 ** See Copyright Notice in lua.h
 */
@@ -83,10 +83,11 @@ typedef struct global_State {
   GCObject **sweepgc;  /* position of sweep in `rootgc' */
   GCObject *gray;  /* list of gray objects */
   GCObject *grayagain;  /* list of objects to be traversed atomically */
-  GCObject *weak;  /* list of (something) weak tables */
-  GCObject *ephemeron;  /* list of ephemeron tables */
+  GCObject *weak;  /* list of tables with weak values */
+  GCObject *ephemeron;  /* list of ephemeron tables (weak keys) */
   GCObject *allweak;  /* list of all-weak tables */
-  GCObject *tmudata;  /* last element of list of userdata to be GC */
+  GCObject *tmudata;  /* list of userdata with finalizers */
+  GCObject *tobefnz;  /* last element of list of userdata to be GC */
   Mbuffer buff;  /* temporary buffer for string concatentation */
   lu_mem GCthreshold;
   lu_mem totalbytes;  /* number of bytes currently allocated */
@@ -143,7 +144,7 @@ struct lua_State {
 ** Union of all collectable objects
 */
 union GCObject {
-  GCheader gch;
+  GCheader gch;  /* common header */
   union TString ts;
   union Udata u;
   union Closure cl;
@@ -154,13 +155,15 @@ union GCObject {
 };
 
 
+#define gch(o)		(&(o)->gch)
+
 /* macros to convert a GCObject into a specific value */
 #define rawgco2ts(o)	check_exp((o)->gch.tt == LUA_TSTRING, &((o)->ts))
 #define gco2ts(o)	(&rawgco2ts(o)->tsv)
 #define rawgco2u(o)	check_exp((o)->gch.tt == LUA_TUSERDATA, &((o)->u))
 #define gco2u(o)	(&rawgco2u(o)->uv)
 #define gco2cl(o)	check_exp((o)->gch.tt == LUA_TFUNCTION, &((o)->cl))
-#define gco2h(o)	check_exp((o)->gch.tt == LUA_TTABLE, &((o)->h))
+#define gco2t(o)	check_exp((o)->gch.tt == LUA_TTABLE, &((o)->h))
 #define gco2p(o)	check_exp((o)->gch.tt == LUA_TPROTO, &((o)->p))
 #define gco2uv(o)	check_exp((o)->gch.tt == LUA_TUPVAL, &((o)->uv))
 #define ngcotouv(o)	check_exp((o)->gch.tt == LUA_TUPVAL, &((o)->uv))

lstring.c

@@ -1,5 +1,5 @@
 /*
-** $Id: lstring.c,v 2.9 2006/07/11 15:53:29 roberto Exp roberto $
+** $Id: lstring.c,v 2.10 2007/11/09 18:55:07 roberto Exp roberto $
 ** String table (keeps all strings handled by Lua)
 ** See Copyright Notice in lua.h
 */
@@ -32,11 +32,11 @@ void luaS_resize (lua_State *L, int newsize) {
   for (i=0; i<tb->size; i++) {
     GCObject *p = tb->hash[i];
     while (p) {  /* for each node in the list */
-      GCObject *next = p->gch.next;  /* save next */
+      GCObject *next = gch(p)->next;  /* save next */
       unsigned int h = gco2ts(p)->hash;
       int h1 = lmod(h, newsize);  /* new position */
       lua_assert(cast_int(h%newsize) == lmod(h, newsize));
-      p->gch.next = newhash[h1];  /* chain it */
+      gch(p)->next = newhash[h1];  /* chain it */
       newhash[h1] = p;
       p = next;
     }
@@ -80,7 +80,7 @@ TString *luaS_newlstr (lua_State *L, const char *str, size_t l) {
     h = h ^ ((h<<5)+(h>>2)+cast(unsigned char, str[l1-1]));
   for (o = G(L)->strt.hash[lmod(h, G(L)->strt.size)];
        o != NULL;
-       o = o->gch.next) {
+       o = gch(o)->next) {
     TString *ts = rawgco2ts(o);
     if (h == ts->tsv.hash && ts->tsv.len == l &&
                              (memcmp(str, getstr(ts), l) == 0)) {
@@ -98,14 +98,10 @@ Udata *luaS_newudata (lua_State *L, size_t s, Table *e) {
   if (s > MAX_SIZET - sizeof(Udata))
     luaM_toobig(L);
   u = cast(Udata *, luaM_malloc(L, s + sizeof(Udata)));
-  u->uv.marked = luaC_white(G(L));  /* is not finalized */
-  u->uv.tt = LUA_TUSERDATA;
+  luaC_link(L, obj2gco(u), LUA_TUSERDATA);
   u->uv.len = s;
   u->uv.metatable = NULL;
   u->uv.env = e;
-  /* chain it on udata list (after main thread) */
-  u->uv.next = G(L)->mainthread->next;
-  G(L)->mainthread->next = obj2gco(u);
   return u;
 }
 

ltests.c

@@ -1,5 +1,5 @@
 /*
-** $Id: ltests.c,v 2.45 2008/02/11 18:04:26 roberto Exp roberto $
+** $Id: ltests.c,v 2.46 2008/02/11 19:04:16 roberto Exp roberto $
 ** Internal Module for Debugging of the Lua Implementation
 ** See Copyright Notice in lua.h
 */
@@ -176,10 +176,10 @@ static int testobjref1 (global_State *g, GCObject *f, GCObject *t) {
 static void printobj (global_State *g, GCObject *o) {
   int i = 0;
   GCObject *p;
-  for (p = g->rootgc; p != o && p != NULL; p = p->gch.next) i++;
+  for (p = g->rootgc; p != o && p != NULL; p = gch(p)->next) i++;
   if (p == NULL) i = -1;
-  printf("%d:%s(%p)-%c(%02X)", i, luaT_typenames[o->gch.tt], (void *)o,
-           isdead(g,o)?'d':isblack(o)?'b':iswhite(o)?'w':'g', o->gch.marked);
+  printf("%d:%s(%p)-%c(%02X)", i, luaT_typenames[gch(o)->tt], (void *)o,
+           isdead(g,o)?'d':isblack(o)?'b':iswhite(o)?'w':'g', gch(o)->marked);
 }
 
 
@@ -198,7 +198,7 @@ static int testobjref (global_State *g, GCObject *f, GCObject *t) {
 #define checkobjref(g,f,t) lua_assert(testobjref(g,f,obj2gco(t)))
 
 #define checkvalref(g,f,t) lua_assert(!iscollectable(t) || \
-	((ttype(t) == (t)->value.gc->gch.tt) && testobjref(g,f,gcvalue(t))))
+	((ttype(t) == gch((t)->value.gc)->tt) && testobjref(g,f,gcvalue(t))))
 
 
 
@@ -285,7 +285,7 @@ static void checkstack (global_State *g, lua_State *L1) {
   CallInfo *ci;
   GCObject *uvo;
   lua_assert(!isdead(g, obj2gco(L1)));
-  for (uvo = L1->openupval; uvo != NULL; uvo = uvo->gch.next) {
+  for (uvo = L1->openupval; uvo != NULL; uvo = gch(uvo)->next) {
     UpVal *uv = gco2uv(uvo);
     lua_assert(uv->v != &uv->u.value);  /* must be open */
     lua_assert(!isblack(uvo));  /* open upvalues cannot be black */
@@ -308,14 +308,14 @@ static void checkstack (global_State *g, lua_State *L1) {
 
 static void checkobject (global_State *g, GCObject *o) {
   if (isdead(g, o))
-/*    lua_assert(g->gcstate == GCSsweepstring || g->gcstate == GCSsweep);*/
-{ if (!(g->gcstate == GCSsweepstring || g->gcstate == GCSsweep))
-printf(">>> %d  %s  %02x\n", g->gcstate, luaT_typenames[o->gch.tt], o->gch.marked);
+/*    lua_assert(issweep(g));*/
+{ if (!issweep(g))
+printf(">>> %d  %s  %02x\n", g->gcstate, luaT_typenames[gch(o)->tt], gch(o)->marked);
 }
   else {
     if (g->gcstate == GCSfinalize)
       lua_assert(iswhite(o));
-    switch (o->gch.tt) {
+    switch (gch(o)->tt) {
       case LUA_TUPVAL: {
         UpVal *uv = gco2uv(o);
         lua_assert(uv->v == &uv->u.value);  /* must be closed */
@@ -329,7 +329,7 @@ printf(">>> %d  %s  %02x\n", g->gcstate, luaT_typenames[o->gch.tt], o->gch.marke
         break;
       }
       case LUA_TTABLE: {
-        checktable(g, gco2h(o));
+        checktable(g, gco2t(o));
         break;
       }
       case LUA_TTHREAD: {
@@ -367,10 +367,10 @@ int lua_checkmemory (lua_State *L) {
   GCObject *o;
   UpVal *uv;
   checkstack(g, g->mainthread);
-  for (o = g->rootgc; o != obj2gco(g->mainthread); o = o->gch.next)
+  for (o = g->rootgc; o != NULL; o = gch(o)->next)
     checkobject(g, o);
-  for (o = o->gch.next; o != NULL; o = o->gch.next) {
-    lua_assert(o->gch.tt == LUA_TUSERDATA);
+  for (o = g->tmudata; o != NULL; o = gch(o)->next) {
+    lua_assert(!isdead(g, o));
     checkobject(g, o);
   }
   for (uv = g->uvhead.u.l.next; uv != &g->uvhead; uv = uv->u.l.next) {
@@ -534,8 +534,10 @@ static int gcstate (lua_State *L) {
   switch(G(L)->gcstate) {
     case GCSpropagate: lua_pushstring(L, "propagate"); break;
     case GCSsweepstring: lua_pushstring(L, "sweep strings"); break;
+    case GCSsweeptmu: lua_pushstring(L, "sweep udata with __gc"); break;
     case GCSsweep: lua_pushstring(L, "sweep"); break;
     case GCSfinalize: lua_pushstring(L, "finalize"); break;
+    default: lua_assert(0);
   }
   return 1;
 }
@@ -612,7 +614,7 @@ static int string_query (lua_State *L) {
   else if (s < tb->size) {
     GCObject *ts;
     int n = 0;
-    for (ts = tb->hash[s]; ts; ts = ts->gch.next) {
+    for (ts = tb->hash[s]; ts; ts = gch(ts)->next) {
       setsvalue2s(L, L->top, gco2ts(ts));
       incr_top(L);
       n++;