From 777061e441ecbb9e3522aa5c88d9204decc9ff81 Mon Sep 17 00:00:00 2001
From: Roberto Ierusalimschy <roberto@inf.puc-rio.br>
Date: Thu, 21 Jun 2001 13:41:34 -0300
Subject: resurect userdata before calling its GC tag method

---
 lgc.c    | 41 ++++++++++++++++++++++++++++-------------
 lgc.h    |  5 ++---
 lstate.c | 10 ++++------
 3 files changed, 34 insertions(+), 22 deletions(-)

diff --git a/lgc.c b/lgc.c
index de5998e3..11119585 100644
--- a/lgc.c
+++ b/lgc.c
@@ -1,5 +1,5 @@
 /*
-** $Id: lgc.c,v 1.105 2001/06/15 19:17:33 roberto Exp roberto $
+** $Id: lgc.c,v 1.106 2001/06/15 20:36:57 roberto Exp roberto $
 ** Garbage Collector
 ** See Copyright Notice in lua.h
 */
@@ -268,7 +268,7 @@ static void collecttable (lua_State *L) {
 }
 
 
-void luaC_collectudata (lua_State *L) {
+static void collectudata (lua_State *L, int keep) {
   Udata **p = &G(L)->rootudata;
   Udata *curr;
   while ((curr = *p) != NULL) {
@@ -279,8 +279,13 @@ void luaC_collectudata (lua_State *L) {
     else {  /* collect */
       int tag = curr->uv.tag;
       *p = curr->uv.next;
-      curr->uv.next = G(L)->TMtable[tag].collected;  /* chain udata */
-      G(L)->TMtable[tag].collected = curr;
+      if (keep ||  /* must keep all of them (to close state)? */
+          luaT_gettm(G(L), tag, TM_GC)) {  /* or is there a GC tag method? */
+        curr->uv.next = G(L)->TMtable[tag].collected;  /* chain udata ... */
+        G(L)->TMtable[tag].collected = curr;  /* ... to call its TM later */
+      }
+      else  /* no tag method; delete udata */
+        luaM_free(L, curr, sizeudata(curr->uv.len));
     }
   }
 }
@@ -327,7 +332,6 @@ static void callgcTM (lua_State *L, const TObject *obj) {
     int oldah = L->allowhooks;
     StkId top = L->top;
     L->allowhooks = 0;  /* stop debug hooks during GC tag methods */
-    luaD_checkstack(L, 2);
     setclvalue(top, tm);
     setobj(top+1, obj);
     L->top += 2;
@@ -338,23 +342,35 @@ static void callgcTM (lua_State *L, const TObject *obj) {
 }
 
 
-void luaC_callgcTMudata (lua_State *L) {
+static void callgcTMudata (lua_State *L) {
   int tag;
+  luaD_checkstack(L, 3);
   for (tag=G(L)->ntag-1; tag>=0; tag--) {  /* for each tag (in reverse order) */
     Udata *udata;
     while ((udata = G(L)->TMtable[tag].collected) != NULL) {
-      TObject obj;
       G(L)->TMtable[tag].collected = udata->uv.next;  /* remove it from list */
-      setuvalue(&obj, udata);
-      callgcTM(L, &obj);
-      luaM_free(L, udata, sizeudata(udata->uv.len));
+      udata->uv.next = G(L)->rootudata;  /* resurect it */
+      G(L)->rootudata = udata;
+      setuvalue(L->top, udata);
+      L->top++;  /* keep it in stack to avoid being (recursively) collected */
+      callgcTM(L, L->top-1);
+      uvalue(L->top-1)->uv.tag = 0;  /* default tag (udata is `finalized') */
+      L->top--;
     }
   }
 }
 
 
+void luaC_callallgcTM (lua_State *L) {
+  if (G(L)->rootudata) {  /* avoid problems with incomplete states */
+    collectudata(L, 1);  /* collect all udata into tag lists */
+    callgcTMudata(L);  /* call their GC tag methods */
+  }
+}
+
+
 void luaC_collect (lua_State *L, int all) {
-  luaC_collectudata(L);
+  collectudata(L, 0);
   collectstrings(L, all);
   collecttable(L);
   collectproto(L);
@@ -367,9 +383,8 @@ void luaC_collectgarbage (lua_State *L) {
   cleartables(G(L));
   luaC_collect(L, 0);
   checkMbuffer(L);
-  G(L)->GCthreshold = 2*G(L)->nblocks;  /* temporary threshold (for TM) */
-  luaC_callgcTMudata(L);
   G(L)->GCthreshold = 2*G(L)->nblocks;  /* new threshold */
+  callgcTMudata(L);
   callgcTM(L, &luaO_nilobject);
 }
 
diff --git a/lgc.h b/lgc.h
index 7268e4c2..7e1e5478 100644
--- a/lgc.h
+++ b/lgc.h
@@ -1,5 +1,5 @@
 /*
-** $Id: lgc.h,v 1.10 2001/06/05 19:27:32 roberto Exp roberto $
+** $Id: lgc.h,v 1.11 2001/06/12 18:43:13 roberto Exp roberto $
 ** Garbage Collector
 ** See Copyright Notice in lua.h
 */
@@ -15,8 +15,7 @@
 			  luaC_collectgarbage(L)
 
 
-void luaC_collectudata (lua_State *L);
-void luaC_callgcTMudata (lua_State *L);
+void luaC_callallgcTM (lua_State *L);
 void luaC_collect (lua_State *L, int all);
 void luaC_collectgarbage (lua_State *L);
 
diff --git a/lstate.c b/lstate.c
index 65c1cde4..6c2c4c17 100644
--- a/lstate.c
+++ b/lstate.c
@@ -1,5 +1,5 @@
 /*
-** $Id: lstate.c,v 1.63 2001/06/06 18:00:19 roberto Exp roberto $
+** $Id: lstate.c,v 1.64 2001/06/12 18:43:13 roberto Exp roberto $
 ** Global State
 ** See Copyright Notice in lua.h
 */
@@ -112,12 +112,10 @@ static void close_state (lua_State *L, lua_State *OL) {
     L->next->previous = L->previous;
   }
   else if (G(L)) {  /* last thread; close global state */
-    while (G(L)->rootudata) {
-      luaC_collectudata(L);  /* collect all user data */
-      luaC_callgcTMudata(L);  /* call their tag methods */
-    }  /* repeat, as tag methods may create new userdata objects */
-    luaC_collect(L, 1);  /* collect all other elements */
+    luaC_callallgcTM(L);  /* call GC tag methods for all udata */
+    luaC_collect(L, 1);  /* collect all elements */
     lua_assert(G(L)->rootproto == NULL);
+    lua_assert(G(L)->rootudata == NULL);
     lua_assert(G(L)->rootcl == NULL);
     lua_assert(G(L)->roottable == NULL);
     luaS_freeall(L);
-- 
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