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avoid clearing ephemeron tables that have nothing to be cleaned

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(no white elements)
This commit is contained in:
Roberto Ierusalimschy 2011-09-19 14:03:38 -03:00
parent 68ce878292
commit 45c346645c
1 changed files with 17 additions and 13 deletions
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30
lgc.c
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@ -1,5 +1,5 @@
/*
** $Id: lgc.c,v 2.108 2010/12/29 18:00:23 roberto Exp roberto $
** $Id: lgc.c,v 2.109 2011/05/05 19:42:25 roberto Exp roberto $
** Garbage Collector
** See Copyright Notice in lua.h
*/
@ -357,7 +357,8 @@ static void traverseweakvalue (global_State *g, Table *h) {
static int traverseephemeron (global_State *g, Table *h) {
int marked = 0; /* true if an object is marked in this traversal */
int hasclears = 0; /* true if table has unmarked pairs */
int hasclears = 0; /* true if table has white keys */
int prop = 0; /* true if table has entry "white-key -> white-value" */
Node *n, *limit = gnode(h, sizenode(h));
int i;
/* traverse array part (numeric keys are 'strong') */
@ -372,19 +373,22 @@ static int traverseephemeron (global_State *g, Table *h) {
checkdeadkey(n);
if (ttisnil(gval(n))) /* entry is empty? */
removeentry(n); /* remove it */
else if (iscleared(gkey(n), 1)) { /* key is not marked (yet)? */
hasclears = 1; /* table still have white keys */
if (valiswhite(gval(n))) /* value not marked yet? */
prop = 1;
}
else if (valiswhite(gval(n))) { /* value not marked yet? */
if (iscleared(gkey(n), 1)) /* key is not marked (yet)? */
hasclears = 1; /* may have to propagate mark from key to value */
else { /* key is marked, so mark value */
marked = 1; /* value was not marked */
reallymarkobject(g, gcvalue(gval(n)));
}
marked = 1; /* mark it now */
reallymarkobject(g, gcvalue(gval(n)));
}
}
if (hasclears) /* does table have unmarked pairs? */
linktable(h, &g->ephemeron); /* will have to propagate again */
else /* nothing to propagate */
linktable(h, &g->weak); /* avoid convergence phase */
if (prop)
linktable(h, &g->ephemeron); /* have to propagate again */
else if (hasclears) /* does table have white keys? */
linktable(h, &g->allweak); /* may have to clean white keys */
else /* no white keys */
linktable(h, &g->grayagain); /* no need to clean */
return marked;
}
@ -868,8 +872,8 @@ static void atomic (lua_State *L) {
/* traverse objects caught by write barrier and by 'remarkupvals' */
propagateall(g);
traverselistofgrays(g, &g->weak); /* remark weak tables */
traverselistofgrays(g, &g->ephemeron); /* remark ephemeron tables */
traverselistofgrays(g, &g->grayagain); /* remark gray again */
traverselistofgrays(g, &g->ephemeron); /* remark ephemeron tables */
convergeephemerons(g);
/* at this point, all strongly accessible objects are marked. */
luaC_separateudata(L, 0); /* separate userdata to be finalized */