From 1cce3e6842fd76099b1973dabd8504566610f068 Mon Sep 17 00:00:00 2001
From: Roberto Ierusalimschy <roberto@inf.puc-rio.br>
Date: Fri, 14 Feb 2014 14:43:14 -0200
Subject: [PATCH] change in the way 'collectgarbage("step", size)' interprets
 'size' (mimicking the way the GC itself behaves when Lua allocates 'size'
 Kbytes)

---
 lapi.c | 22 +++++++++++++++-------
 lgc.c  | 22 +++++++---------------
 lgc.h  |  3 +--
 3 files changed, 23 insertions(+), 24 deletions(-)

diff --git a/lapi.c b/lapi.c
index d5765cc9..cb38ffba 100644
--- a/lapi.c
+++ b/lapi.c
@@ -1,5 +1,5 @@
 /*
-** $Id: lapi.c,v 2.194 2014/02/13 12:11:34 roberto Exp roberto $
+** $Id: lapi.c,v 2.195 2014/02/13 17:25:20 roberto Exp roberto $
 ** Lua API
 ** See Copyright Notice in lua.h
 */
@@ -1070,12 +1070,20 @@ LUA_API int lua_gc (lua_State *L, int what, int data) {
       break;
     }
     case LUA_GCSTEP: {
-      lu_mem debt = cast(lu_mem, data) * 1024 - GCSTEPSIZE;
-      if (g->gcrunning)
-        debt += g->GCdebt;  /* include current debt */
-      luaE_setdebt(g, debt);
-      luaC_forcestep(L);
-      if (g->gcstate == GCSpause)  /* end of cycle? */
+      l_mem debt = 1;  /* =1 to signal that it did an actual step */
+      int oldrunning = g->gcrunning;
+      g->gcrunning = 1;  /* force GC to run */
+      if (data == 0) {
+        luaE_setdebt(g, -GCSTEPSIZE);  /* to do a "small" step */
+        luaC_step(L);
+      }
+      else {  /* add 'data' to total debt */
+        debt = cast(l_mem, data) * 1024 + g->GCdebt;
+        luaE_setdebt(g, debt);
+        luaC_checkGC(L);
+      }
+      g->gcrunning = oldrunning;  /* restore previous state */
+      if (debt > 0 && g->gcstate == GCSpause)  /* end of cycle? */
         res = 1;  /* signal it */
       break;
     }
diff --git a/lgc.c b/lgc.c
index ea0537df..5c365e32 100644
--- a/lgc.c
+++ b/lgc.c
@@ -1,5 +1,5 @@
 /*
-** $Id: lgc.c,v 2.172 2014/02/13 14:46:38 roberto Exp roberto $
+** $Id: lgc.c,v 2.173 2014/02/13 17:25:20 roberto Exp roberto $
 ** Garbage Collector
 ** See Copyright Notice in lua.h
 */
@@ -1087,11 +1087,15 @@ static l_mem getdebt (global_State *g) {
 }
 
 /*
-** performs a basic GC step
+** performs a basic GC step when collector is running
 */
-void luaC_forcestep (lua_State *L) {
+void luaC_step (lua_State *L) {
   global_State *g = G(L);
   l_mem debt = getdebt(g);
+  if (!g->gcrunning) {  /* not running? */
+    luaE_setdebt(g, -GCSTEPSIZE * 10);  /* avoid being called too often */
+    return;
+  }
   do {
     if (g->gcstate == GCScallfin && g->tobefnz) {
       unsigned int n = runafewfinalizers(L);
@@ -1112,18 +1116,6 @@ void luaC_forcestep (lua_State *L) {
 }
 
 
-/*
-** performs a basic GC step when collector is running
-*/
-void luaC_step (lua_State *L) {
-  if (!G(L)->gcrunning)
-    luaE_setdebt(G(L), -GCSTEPSIZE);  /* avoid being called too often */
-  else
-    luaC_forcestep(L);
-}
-
-
-
 /*
 ** performs a full GC cycle; if "isemergency", does not call
 ** finalizers (which could change stack positions)
diff --git a/lgc.h b/lgc.h
index a9e497c7..0e24d2c3 100644
--- a/lgc.h
+++ b/lgc.h
@@ -1,5 +1,5 @@
 /*
-** $Id: lgc.h,v 2.78 2014/02/13 12:11:34 roberto Exp roberto $
+** $Id: lgc.h,v 2.79 2014/02/13 14:46:38 roberto Exp roberto $
 ** Garbage Collector
 ** See Copyright Notice in lua.h
 */
@@ -126,7 +126,6 @@
 LUAI_FUNC void luaC_fix (lua_State *L, GCObject *o);
 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);