From 868ff40339fc72b7bf3c916afcdc2a992398346c Mon Sep 17 00:00:00 2001
From: Roberto Ierusalimschy <roberto@inf.puc-rio.br>
Date: Wed, 29 Dec 2010 16:00:23 -0200
Subject: full collection does not restart collector + avoid changing GC state
 if an error happens in a step

---
 lapi.c | 10 +++-------
 lgc.c  | 32 ++++++++++++++++++++------------
 lgc.h  |  3 ++-
 3 files changed, 25 insertions(+), 20 deletions(-)

diff --git a/lapi.c b/lapi.c
index 73cf1108..9b824577 100644
--- a/lapi.c
+++ b/lapi.c
@@ -1,5 +1,5 @@
 /*
-** $Id: lapi.c,v 2.142 2010/12/20 18:17:46 roberto Exp roberto $
+** $Id: lapi.c,v 2.143 2010/12/20 19:40:07 roberto Exp roberto $
 ** Lua API
 ** See Copyright Notice in lua.h
 */
@@ -969,7 +969,6 @@ LUA_API int lua_gc (lua_State *L, int what, int data) {
       break;
     }
     case LUA_GCCOLLECT: {
-      g->gcrunning = 1;  /* restart collector if stopped ?? */
       luaC_fullgc(L, 0);
       break;
     }
@@ -983,22 +982,19 @@ LUA_API int lua_gc (lua_State *L, int what, int data) {
       break;
     }
     case LUA_GCSTEP: {
-      int running = g->gcrunning;
-      g->gcrunning = 1;  /* allow steps */
       if (g->gckind == KGC_GEN) {  /* generational mode? */
         res = (g->lastmajormem == 0);  /* 1 if will do major collection */
-        luaC_step(L);  /* do a single step */
+        luaC_forcestep(L);  /* do a single step */
       }
       else {
         while (data-- >= 0) {
-          luaC_step(L);
+          luaC_forcestep(L);
           if (g->gcstate == GCSpause) {  /* end of cycle? */
             res = 1;  /* signal it */
             break;
           }
         }
       }
-      g->gcrunning = running;  /* restore previous state */
       break;
     }
     case LUA_GCSETPAUSE: {
diff --git a/lgc.c b/lgc.c
index 933b035b..55101120 100644
--- a/lgc.c
+++ b/lgc.c
@@ -1,5 +1,5 @@
 /*
-** $Id: lgc.c,v 2.106 2010/12/20 18:17:46 roberto Exp roberto $
+** $Id: lgc.c,v 2.107 2010/12/20 19:40:07 roberto Exp roberto $
 ** Garbage Collector
 ** See Copyright Notice in lua.h
 */
@@ -318,8 +318,7 @@ static void remarkupvals (global_State *g) {
 ** mark root set and reset all gray lists, to start a new
 ** incremental (or full) collection
 */
-static void markroot (lua_State *L) {
-  global_State *g = G(L);
+static void markroot (global_State *g) {
   g->gray = g->grayagain = NULL;
   g->weak = g->allweak = g->ephemeron = NULL;
   markobject(g, g->mainthread);
@@ -889,7 +888,7 @@ static l_mem singlestep (lua_State *L) {
   switch (g->gcstate) {
     case GCSpause: {
       if (!isgenerational(g))
-        markroot(L);  /* start a new collection */
+        markroot(g);  /* start a new collection */
       /* in any case, root must be marked */
       lua_assert(!iswhite(obj2gco(g->mainthread))
               && !iswhite(gcvalue(&g->l_registry)));
@@ -986,15 +985,24 @@ static void step (lua_State *L) {
 }
 
 
-void luaC_step (lua_State *L) {
+/*
+** performs a basic GC step even if the collector is stopped
+*/
+void luaC_forcestep (lua_State *L) {
   global_State *g = G(L);
-  if (g->gcrunning) {
-    int i;
-    if (isgenerational(g)) generationalcollection(L);
-    else step(L);
-    for (i = 0; i < GCFINALIZENUM && g->tobefnz; i++)
-      GCTM(L, 1);  /* Call a few pending finalizers */
-  }
+  int i;
+  if (isgenerational(g)) generationalcollection(L);
+  else step(L);
+  for (i = 0; i < GCFINALIZENUM && g->tobefnz; i++)
+    GCTM(L, 1);  /* Call a few pending finalizers */
+}
+
+
+/*
+** performs a basic GC step only if collector is running
+*/
+void luaC_step (lua_State *L) {
+  if (G(L)->gcrunning) luaC_forcestep(L);
 }
 
 
diff --git a/lgc.h b/lgc.h
index 8a430294..b0520f36 100644
--- a/lgc.h
+++ b/lgc.h
@@ -1,5 +1,5 @@
 /*
-** $Id: lgc.h,v 2.47 2010/12/17 12:02:29 roberto Exp roberto $
+** $Id: lgc.h,v 2.48 2010/12/20 18:17:46 roberto Exp roberto $
 ** Garbage Collector
 ** See Copyright Notice in lua.h
 */
@@ -128,6 +128,7 @@
 LUAI_FUNC void luaC_separateudata (lua_State *L, int all);
 LUAI_FUNC void luaC_freeallobjects (lua_State *L);
 LUAI_FUNC void luaC_step (lua_State *L);
+LUAI_FUNC void luaC_forcestep (lua_State *L);
 LUAI_FUNC void luaC_runtilstate (lua_State *L, int statesmask);
 LUAI_FUNC void luaC_fullgc (lua_State *L, int isemergency);
 LUAI_FUNC GCObject *luaC_newobj (lua_State *L, int tt, size_t sz,
-- 
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