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new algorithm for traversing in GC to avoid deep recursion calls

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This commit is contained in:
Roberto Ierusalimschy
2000-08-07 17:21:34 -03:00
parent 397905ef86
commit d9e61e8cea
8 changed files with 148 additions and 117 deletions
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154
lgc.c
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@@ -1,5 +1,5 @@
/*
** $Id: lgc.c,v 1.58 2000/06/26 19:28:31 roberto Exp roberto $
** $Id: lgc.c,v 1.59 2000/06/30 14:35:17 roberto Exp roberto $
** Garbage Collector
** See Copyright Notice in lua.h
*/
@@ -20,97 +20,94 @@
#include "ltm.h"
typedef struct GCState {
Hash *tmark; /* list of marked tables to be visited */
Closure *cmark; /* list of marked closures to be visited */
} GCState;
static int markobject (lua_State *L, TObject *o);
static int markobject (GCState *st, TObject *o);
/* mark a string; marks larger than 1 cannot be changed */
#define strmark(L, s) {if ((s)->marked == 0) (s)->marked = 1;}
#define strmark(s) {if ((s)->marked == 0) (s)->marked = 1;}
static void protomark (lua_State *L, Proto *f) {
static void protomark (Proto *f) {
if (!f->marked) {
int i;
f->marked = 1;
strmark(L, f->source);
strmark(f->source);
for (i=0; i<f->nkstr; i++)
strmark(L, f->kstr[i]);
strmark(f->kstr[i]);
for (i=0; i<f->nkproto; i++)
protomark(L, f->kproto[i]);
protomark(f->kproto[i]);
if (f->locvars) { /* is there debug information? */
LocVar *lv;
for (lv=f->locvars; lv->pc != -1; lv++) /* mark local-variable names */
if (lv->varname) strmark(L, lv->varname);
if (lv->varname) strmark(lv->varname);
}
}
}
static void closuremark (lua_State *L, Closure *f) {
if (!f->marked) {
int i = f->nupvalues;
f->marked = 1;
while (i--)
markobject(L, &f->upvalue[i]);
}
}
static void tablemark (lua_State *L, Hash *h) {
if (!h->marked) {
int i;
h->marked = 1;
for (i=h->size-1; i>=0; i--) {
Node *n = node(h,i);
if (ttype(key(n)) != TAG_NIL) {
if (ttype(val(n)) == TAG_NIL)
luaH_remove(h, key(n)); /* dead element; try to remove it */
markobject(L, &n->key);
markobject(L, &n->val);
}
}
}
}
static void travstack (lua_State *L) {
static void markstack (lua_State *L, GCState *st) {
StkId o;
for (o=L->stack; o<L->top; o++)
markobject(L, o);
markobject(st, o);
}
static void travlock (lua_State *L) {
static void marklock (lua_State *L, GCState *st) {
int i;
for (i=0; i<L->refSize; i++) {
if (L->refArray[i].st == LOCK)
markobject(L, &L->refArray[i].o);
markobject(st, &L->refArray[i].o);
}
}
static int markobject (lua_State *L, TObject *o) {
static void marktagmethods (lua_State *L, GCState *st) {
int e;
for (e=0; e<IM_N; e++) {
int t;
for (t=0; t<=L->last_tag; t++)
markobject(st, luaT_getim(L, t,e));
}
}
static int markobject (GCState *st, TObject *o) {
switch (ttype(o)) {
case TAG_USERDATA: case TAG_STRING:
strmark(L, tsvalue(o));
strmark(tsvalue(o));
break;
case TAG_TABLE:
tablemark(L, hvalue(o));
break;
case TAG_LCLOSURE:
protomark(L, clvalue(o)->f.l);
closuremark(L, clvalue(o));
break;
case TAG_LMARK: {
Closure *cl = infovalue(o)->func;
protomark(L, cl->f.l);
closuremark(L, cl);
case TAG_TABLE: {
if (!ismarked(hvalue(o))) {
hvalue(o)->mark = st->tmark; /* chain it in list of marked */
st->tmark = hvalue(o);
}
break;
}
case TAG_LMARK: {
Closure *cl = infovalue(o)->func;
if (!ismarked(cl)) {
protomark(cl->f.l);
cl->mark = st->cmark; /* chain it for later traversal */
st->cmark = cl;
}
break;
}
case TAG_LCLOSURE:
protomark(clvalue(o)->f.l);
/* go through */
case TAG_CCLOSURE: case TAG_CMARK:
closuremark(L, clvalue(o));
if (!ismarked(clvalue(o))) {
clvalue(o)->mark = st->cmark; /* chain it for later traversal */
st->cmark = clvalue(o);
}
break;
default: break; /* numbers, etc */
}
@@ -118,6 +115,41 @@ static int markobject (lua_State *L, TObject *o) {
}
static void markall (lua_State *L) {
GCState st;
st.cmark = NULL;
st.tmark = L->gt; /* put table of globals in mark list */
L->gt->mark = NULL;
marktagmethods(L, &st); /* mark tag methods */
markstack(L, &st); /* mark stack objects */
marklock(L, &st); /* mark locked objects */
for (;;) { /* mark tables and closures */
if (st.cmark) {
int i;
Closure *f = st.cmark; /* get first closure from list */
st.cmark = f->mark; /* remove it from list */
for (i=0; i<f->nupvalues; i++) /* mark its upvalues */
markobject(&st, &f->upvalue[i]);
}
else if (st.tmark) {
int i;
Hash *h = st.tmark; /* get first table from list */
st.tmark = h->mark; /* remove it from list */
for (i=0; i<h->size; i++) {
Node *n = node(h, i);
if (ttype(key(n)) != TAG_NIL) {
if (ttype(val(n)) == TAG_NIL)
luaH_remove(h, key(n)); /* dead element; try to remove it */
markobject(&st, &n->key);
markobject(&st, &n->val);
}
}
}
else break; /* nothing else to mark */
}
}
static void collectproto (lua_State *L) {
Proto **p = &L->rootproto;
Proto *next;
@@ -138,8 +170,8 @@ static void collectclosure (lua_State *L) {
Closure **p = &L->rootcl;
Closure *next;
while ((next = *p) != NULL) {
if (next->marked) {
next->marked = 0;
if (ismarked(next)) {
next->mark = next; /* unmark */
p = &next->next;
}
else {
@@ -154,8 +186,8 @@ static void collecttable (lua_State *L) {
Hash **p = &L->roottable;
Hash *next;
while ((next = *p) != NULL) {
if (next->marked) {
next->marked = 0;
if (ismarked(next)) {
next->mark = next; /* unmark */
p = &next->next;
}
else {
@@ -256,14 +288,6 @@ static void callgcTMudata (lua_State *L) {
}
static void markall (lua_State *L) {
luaT_travtagmethods(L, markobject); /* mark tag methods */
travstack(L); /* mark stack objects */
tablemark(L, L->gt); /* mark global variables */
travlock(L); /* mark locked objects */
}
void luaC_collect (lua_State *L, int all) {
int oldah = L->allowhooks;
L->allowhooks = 0; /* stop debug hooks during GC */