From 0e0e4a480e6d9b0125a96ca982a3e9571578a037 Mon Sep 17 00:00:00 2001
From: Roberto Ierusalimschy <roberto@inf.puc-rio.br>
Date: Wed, 11 Apr 2001 11:42:41 -0300
Subject: first implementation for weak tables
---
lgc.c | 59 ++++++++++++++++++++++++++++++++++++++++++++---------------
1 file changed, 44 insertions(+), 15 deletions(-)
(limited to 'lgc.c')
diff --git a/lgc.c b/lgc.c
index 3a665660..a7f96f8c 100644
--- a/lgc.c
+++ b/lgc.c
@@ -1,5 +1,5 @@
/*
-** $Id: lgc.c,v 1.94 2001/03/07 18:09:25 roberto Exp roberto $
+** $Id: lgc.c,v 1.95 2001/03/26 14:31:49 roberto Exp roberto $
** Garbage Collector
** See Copyright Notice in lua.h
*/
@@ -38,9 +38,6 @@ typedef struct GCState {
-static void markobject (GCState *st, TObject *o);
-
-
/* mark a string; marks larger than 1 cannot be changed */
#define strmark(s) {if ((s)->marked == 0) (s)->marked = 1;}
@@ -144,22 +141,30 @@ static void traverseclosure (GCState *st, Closure *f) {
}
+static void removekey (Node *n) {
+ if (ttype_key(n) != LUA_TNIL && ttype_key(n) != LUA_TNUMBER)
+ n->key_value.ts = NULL; /* dead key; remove it */
+}
+
+
static void traversetable (GCState *st, Hash *h) {
int i;
+ int mode = h->weakmode;
+ if (mode == (LUA_WEAK_KEY | LUA_WEAK_VALUE))
+ return; /* avoid traversing if both keys and values are weak */
for (i=0; i<h->size; i++) {
Node *n = node(h, i);
- if (ttype(val(n)) == LUA_TNIL) {
- if (ttype_key(n) != LUA_TNIL)
- n->key_value.ts = NULL; /* dead key; remove it */
- }
+ if (ttype(val(n)) == LUA_TNIL)
+ removekey(n);
else {
lua_assert(ttype_key(n) != LUA_TNIL);
- if (ttype_key(n) != LUA_TNUMBER) {
- TObject o;
- setkey2obj(&o, n);
- markobject(st, &o);
+ if (ttype_key(n) != LUA_TNUMBER && !(mode & LUA_WEAK_KEY)) {
+ TObject k;
+ setkey2obj(&k, n);
+ markobject(st, &k);
}
- markobject(st, &n->val);
+ if (!(mode & LUA_WEAK_VALUE))
+ markobject(st, &n->val);
}
}
}
@@ -190,7 +195,6 @@ static void markall (lua_State *L) {
static int hasmark (const TObject *o) {
- /* valid only for locked objects */
switch (ttype(o)) {
case LUA_TSTRING: case LUA_TUSERDATA:
return tsvalue(o)->marked;
@@ -198,7 +202,7 @@ static int hasmark (const TObject *o) {
return ismarked(hvalue(o));
case LUA_TFUNCTION:
return ismarked(clvalue(o));
- default: /* number */
+ default: /* number, nil */
return 1;
}
}
@@ -224,6 +228,30 @@ static void invalidaterefs (global_State *G) {
}
+static void invalidatetable (Hash *h) {
+ int i;
+ for (i=0; i<h->size; i++) {
+ Node *n = node(h, i);
+ TObject k;
+ if (ttype(val(n)) == LUA_TNIL) continue; /* empty node */
+ setkey2obj(&k, n);
+ if (!hasmark(val(n)) || !hasmark(&k)) {
+ setnilvalue(val(n)); /* remove value */
+ removekey(n);
+ }
+ }
+}
+
+
+static void invalidatetables (global_State *G) {
+ Hash *h;
+ for (h = G->roottable; h; h = h->next) {
+ if (ismarked(h) && h->weakmode)
+ invalidatetable(h);
+ }
+}
+
+
static void collectproto (lua_State *L) {
Proto **p = &G(L)->rootproto;
@@ -381,6 +409,7 @@ void luaC_collect (lua_State *L, int all) {
void luaC_collectgarbage (lua_State *L) {
markall(L);
invalidaterefs(G(L)); /* check unlocked references */
+ invalidatetables(G(L));
luaC_collect(L, 0);
checkMbuffer(L);
G(L)->GCthreshold = 2*G(L)->nblocks; /* set new threshold */
--
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