From 89e8303f4ea5f1041f3633db7948e7aef17b5226 Mon Sep 17 00:00:00 2001
From: Roberto Ierusalimschy <roberto@inf.puc-rio.br>
Date: Tue, 12 Jun 2001 15:43:13 -0300
Subject: more robust treatment of GC tag methods (now they can create new
 objects while running...)

---
 lgc.c    | 29 +++++++----------------------
 lgc.h    |  4 +++-
 lstate.c |  9 ++++++---
 3 files changed, 16 insertions(+), 26 deletions(-)

diff --git a/lgc.c b/lgc.c
index e7d533d3..d3c9490c 100644
--- a/lgc.c
+++ b/lgc.c
@@ -1,5 +1,5 @@
 /*
-** $Id: lgc.c,v 1.101 2001/06/07 15:01:21 roberto Exp roberto $
+** $Id: lgc.c,v 1.102 2001/06/08 19:01:38 roberto Exp roberto $
 ** Garbage Collector
 ** See Copyright Notice in lua.h
 */
@@ -18,18 +18,6 @@
 #include "ltm.h"
 
 
-/*
-** optional lock for GC
-** (when Lua calls GC tag methods it unlocks the regular lock)
-*/
-#ifndef lua_lockgc
-#define lua_lockgc(L)		{
-#endif
-
-#ifndef lua_unlockgc
-#define lua_unlockgc(L)		}
-#endif
-
 
 typedef struct GCState {
   Hash *tmark;  /* list of marked tables to be visited */
@@ -281,7 +269,7 @@ static void collecttable (lua_State *L) {
 }
 
 
-static void collectudata (lua_State *L) {
+void luaC_collectudata (lua_State *L) {
   Udata **p = &G(L)->rootudata;
   Udata *next;
   while ((next = *p) != NULL) {
@@ -351,9 +339,8 @@ static void callgcTM (lua_State *L, const TObject *obj) {
 }
 
 
-static void callgcTMudata (lua_State *L) {
+void luaC_callgcTMudata (lua_State *L) {
   int tag;
-  G(L)->GCthreshold = 2*G(L)->nblocks;  /* avoid GC during tag methods */
   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) {
@@ -368,14 +355,14 @@ static void callgcTMudata (lua_State *L) {
 
 
 void luaC_collect (lua_State *L, int all) {
-  lua_lockgc(L);
-  collectudata(L);
-  callgcTMudata(L);
+  luaC_collectudata(L);
   collectstrings(L, all);
   collecttable(L);
   collectproto(L);
   collectclosure(L);
-  lua_unlockgc(L);
+  checkMbuffer(L);
+  G(L)->GCthreshold = 2*G(L)->nblocks;  /* set new threshold */
+  luaC_callgcTMudata(L);
 }
 
 
@@ -383,8 +370,6 @@ void luaC_collectgarbage (lua_State *L) {
   markall(L);
   invalidatetables(G(L));
   luaC_collect(L, 0);
-  checkMbuffer(L);
-  G(L)->GCthreshold = 2*G(L)->nblocks;  /* set new threshold */
   callgcTM(L, &luaO_nilobject);
 }
 
diff --git a/lgc.h b/lgc.h
index 82f19b76..7268e4c2 100644
--- a/lgc.h
+++ b/lgc.h
@@ -1,5 +1,5 @@
 /*
-** $Id: lgc.h,v 1.9 2001/02/02 16:23:20 roberto Exp roberto $
+** $Id: lgc.h,v 1.10 2001/06/05 19:27:32 roberto Exp roberto $
 ** Garbage Collector
 ** See Copyright Notice in lua.h
 */
@@ -15,6 +15,8 @@
 			  luaC_collectgarbage(L)
 
 
+void luaC_collectudata (lua_State *L);
+void luaC_callgcTMudata (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 194e92c1..65c1cde4 100644
--- a/lstate.c
+++ b/lstate.c
@@ -1,5 +1,5 @@
 /*
-** $Id: lstate.c,v 1.62 2001/04/17 17:35:54 roberto Exp roberto $
+** $Id: lstate.c,v 1.63 2001/06/06 18:00:19 roberto Exp roberto $
 ** Global State
 ** See Copyright Notice in lua.h
 */
@@ -112,11 +112,14 @@ static void close_state (lua_State *L, lua_State *OL) {
     L->next->previous = L->previous;
   }
   else if (G(L)) {  /* last thread; close global state */
-    luaC_collect(L, 1);  /* collect all elements */
+    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 */
     lua_assert(G(L)->rootproto == NULL);
     lua_assert(G(L)->rootcl == NULL);
     lua_assert(G(L)->roottable == NULL);
-    lua_assert(G(L)->rootudata == NULL);
     luaS_freeall(L);
     luaM_freearray(L, G(L)->TMtable, G(L)->sizeTM, struct TM);
     luaM_freearray(L, G(L)->Mbuffer, G(L)->Mbuffsize, l_char);
-- 
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