mirror of
https://github.com/lua/lua
synced 2024-11-22 21:01:26 +03:00
391 lines
9.4 KiB
C
391 lines
9.4 KiB
C
/*
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** $Id: lgc.c,v 1.106 2001/06/15 20:36:57 roberto Exp roberto $
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** Garbage Collector
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** See Copyright Notice in lua.h
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*/
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#define LUA_PRIVATE
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#include "lua.h"
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#include "ldo.h"
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#include "lfunc.h"
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#include "lgc.h"
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#include "lmem.h"
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#include "lobject.h"
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#include "lstate.h"
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#include "lstring.h"
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#include "ltable.h"
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#include "ltm.h"
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typedef struct GCState {
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Hash *tmark; /* list of marked tables to be visited */
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Closure *cmark; /* list of marked closures to be visited */
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} GCState;
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/* mark a string; marks larger than 1 cannot be changed */
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#define strmark(s) {if ((s)->tsv.marked == 0) (s)->tsv.marked = 1;}
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static void protomark (Proto *f) {
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if (!f->marked) {
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int i;
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f->marked = 1;
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strmark(f->source);
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for (i=0; i<f->sizek; i++) {
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if (ttype(f->k+i) == LUA_TSTRING)
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strmark(tsvalue(f->k+i));
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}
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for (i=0; i<f->sizekproto; i++)
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protomark(f->kproto[i]);
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for (i=0; i<f->sizelocvars; i++) /* mark local-variable names */
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strmark(f->locvars[i].varname);
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}
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}
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static void markclosure (GCState *st, Closure *cl) {
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if (!ismarked(cl)) {
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if (!cl->isC) {
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lua_assert(cl->nupvalues == cl->f.l->nupvalues);
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protomark(cl->f.l);
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}
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cl->mark = st->cmark; /* chain it for later traversal */
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st->cmark = cl;
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}
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}
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static void marktable (GCState *st, Hash *h) {
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if (!ismarked(h)) {
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h->mark = st->tmark; /* chain it for later traversal */
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st->tmark = h;
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}
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}
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static void markobject (GCState *st, TObject *o) {
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switch (ttype(o)) {
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case LUA_TSTRING:
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strmark(tsvalue(o));
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break;
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case LUA_TUSERDATA:
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if (!ismarkedudata(uvalue(o)))
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switchudatamark(uvalue(o));
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break;
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case LUA_TFUNCTION:
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markclosure(st, clvalue(o));
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break;
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case LUA_TTABLE: {
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marktable(st, hvalue(o));
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break;
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}
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default: break; /* numbers, etc */
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}
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}
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static void markstacks (lua_State *L, GCState *st) {
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lua_State *L1 = L;
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do { /* for each thread */
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StkId o, lim;
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marktable(st, L1->gt); /* mark table of globals */
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for (o=L1->stack; o<L1->top; o++)
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markobject(st, o);
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lim = (L1->stack_last - L1->ci->base > MAXSTACK) ? L1->ci->base+MAXSTACK
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: L1->stack_last;
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for (; o<=lim; o++) setnilvalue(o);
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lua_assert(L1->previous->next == L1 && L1->next->previous == L1);
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L1 = L1->next;
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} while (L1 != L);
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}
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static void marktagmethods (global_State *G, GCState *st) {
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int t;
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for (t=0; t<G->ntag; t++) {
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struct TM *tm = &G->TMtable[t];
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int e;
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if (tm->name) strmark(tm->name);
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for (e=0; e<TM_N; e++) {
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Closure *cl = tm->method[e];
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if (cl) markclosure(st, cl);
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}
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}
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}
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static void traverseclosure (GCState *st, Closure *f) {
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int i;
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for (i=0; i<f->nupvalues; i++) /* mark its upvalues */
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markobject(st, &f->upvalue[i]);
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}
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static void removekey (Node *n) {
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lua_assert(ttype(val(n)) == LUA_TNIL);
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if (ttype_key(n) != LUA_TNIL && ttype_key(n) != LUA_TNUMBER)
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ttype_key(n) = LUA_TNONE; /* dead key; remove it */
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}
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static void traversetable (GCState *st, Hash *h) {
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int i;
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int mode = h->weakmode;
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if (mode == (LUA_WEAK_KEY | LUA_WEAK_VALUE))
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return; /* avoid traversing if both keys and values are weak */
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for (i=0; i<h->size; i++) {
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Node *n = node(h, i);
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if (ttype(val(n)) == LUA_TNIL)
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removekey(n);
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else {
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lua_assert(ttype_key(n) != LUA_TNIL);
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if (ttype_key(n) != LUA_TNUMBER && !(mode & LUA_WEAK_KEY)) {
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TObject k;
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setkey2obj(&k, n);
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markobject(st, &k);
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}
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if (!(mode & LUA_WEAK_VALUE))
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markobject(st, &n->val);
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}
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}
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}
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static void markall (lua_State *L) {
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GCState st;
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st.cmark = NULL;
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st.tmark = NULL;
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marktagmethods(G(L), &st); /* mark tag methods */
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markstacks(L, &st); /* mark all stacks */
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marktable(&st, G(L)->type2tag);
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marktable(&st, G(L)->registry);
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marktable(&st, G(L)->weakregistry);
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for (;;) { /* mark tables and closures */
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if (st.cmark) {
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Closure *f = st.cmark; /* get first closure from list */
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st.cmark = f->mark; /* remove it from list */
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traverseclosure(&st, f);
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}
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else if (st.tmark) {
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Hash *h = st.tmark; /* get first table from list */
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st.tmark = h->mark; /* remove it from list */
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traversetable(&st, h);
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}
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else break; /* nothing else to mark */
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}
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}
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static int hasmark (int tt, Value *v) {
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switch (tt) {
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case LUA_TSTRING:
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return v->ts->tsv.marked;
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case LUA_TUSERDATA:
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return ismarkedudata(v->u);
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case LUA_TTABLE:
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return ismarked(v->h);
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case LUA_TFUNCTION:
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return ismarked(v->cl);
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default: /* number, nil */
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return 1;
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}
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}
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static void cleardeadnodes (Hash *h) {
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int i;
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for (i=0; i<h->size; i++) {
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Node *n = node(h, i);
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if (ttype(val(n)) == LUA_TNIL) continue; /* empty node */
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if (!hasmark(ttype(val(n)), &(val(n)->value)) ||
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!hasmark(ttype_key(n), &n->key_value)) {
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setnilvalue(val(n)); /* remove value */
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removekey(n);
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}
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}
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}
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static void cleartables (global_State *G) {
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Hash *h;
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for (h = G->roottable; h; h = h->next) {
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if (h->weakmode && ismarked(h))
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cleardeadnodes(h);
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}
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}
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static void collectproto (lua_State *L) {
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Proto **p = &G(L)->rootproto;
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Proto *curr;
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while ((curr = *p) != NULL) {
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if (curr->marked) {
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curr->marked = 0;
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p = &curr->next;
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}
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else {
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*p = curr->next;
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luaF_freeproto(L, curr);
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}
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}
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}
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static void collectclosure (lua_State *L) {
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Closure **p = &G(L)->rootcl;
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Closure *curr;
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while ((curr = *p) != NULL) {
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if (ismarked(curr)) {
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curr->mark = curr; /* unmark */
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p = &curr->next;
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}
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else {
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*p = curr->next;
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luaF_freeclosure(L, curr);
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}
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}
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}
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static void collecttable (lua_State *L) {
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Hash **p = &G(L)->roottable;
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Hash *curr;
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while ((curr = *p) != NULL) {
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if (ismarked(curr)) {
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curr->mark = curr; /* unmark */
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p = &curr->next;
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}
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else {
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*p = curr->next;
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luaH_free(L, curr);
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}
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}
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}
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static void collectudata (lua_State *L, int keep) {
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Udata **p = &G(L)->rootudata;
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Udata *curr;
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while ((curr = *p) != NULL) {
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if (ismarkedudata(curr)) {
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switchudatamark(curr); /* unmark */
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p = &curr->uv.next;
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}
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else { /* collect */
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int tag = curr->uv.tag;
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*p = curr->uv.next;
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if (keep || /* must keep all of them (to close state)? */
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luaT_gettm(G(L), tag, TM_GC)) { /* or is there a GC tag method? */
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curr->uv.next = G(L)->TMtable[tag].collected; /* chain udata ... */
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G(L)->TMtable[tag].collected = curr; /* ... to call its TM later */
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}
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else /* no tag method; delete udata */
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luaM_free(L, curr, sizeudata(curr->uv.len));
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}
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}
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}
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static void collectstrings (lua_State *L, int all) {
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int i;
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for (i=0; i<G(L)->strt.size; i++) { /* for each list */
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TString **p = &G(L)->strt.hash[i];
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TString *curr;
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while ((curr = *p) != NULL) {
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if (curr->tsv.marked && !all) { /* preserve? */
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if (curr->tsv.marked < FIXMARK) /* does not change FIXMARKs */
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curr->tsv.marked = 0;
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p = &curr->tsv.nexthash;
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}
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else { /* collect */
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*p = curr->tsv.nexthash;
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G(L)->strt.nuse--;
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luaM_free(L, curr, sizestring(curr->tsv.len));
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}
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}
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}
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if (G(L)->strt.nuse < (ls_nstr)(G(L)->strt.size/4) &&
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G(L)->strt.size > MINPOWER2)
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luaS_resize(L, G(L)->strt.size/2); /* table is too big */
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}
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#define MINBUFFER 256
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static void checkMbuffer (lua_State *L) {
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if (G(L)->Mbuffsize > MINBUFFER*2) { /* is buffer too big? */
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size_t newsize = G(L)->Mbuffsize/2; /* still larger than MINBUFFER */
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luaM_reallocvector(L, G(L)->Mbuffer, G(L)->Mbuffsize, newsize, l_char);
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G(L)->Mbuffsize = newsize;
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}
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}
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static void callgcTM (lua_State *L, const TObject *obj) {
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Closure *tm = luaT_gettmbyObj(G(L), obj, TM_GC);
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if (tm != NULL) {
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int oldah = L->allowhooks;
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StkId top = L->top;
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L->allowhooks = 0; /* stop debug hooks during GC tag methods */
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setclvalue(top, tm);
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setobj(top+1, obj);
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L->top += 2;
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luaD_call(L, top);
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L->top = top; /* restore top */
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L->allowhooks = oldah; /* restore hooks */
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}
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}
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static void callgcTMudata (lua_State *L) {
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int tag;
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luaD_checkstack(L, 3);
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for (tag=G(L)->ntag-1; tag>=0; tag--) { /* for each tag (in reverse order) */
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Udata *udata;
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while ((udata = G(L)->TMtable[tag].collected) != NULL) {
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G(L)->TMtable[tag].collected = udata->uv.next; /* remove it from list */
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udata->uv.next = G(L)->rootudata; /* resurect it */
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G(L)->rootudata = udata;
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setuvalue(L->top, udata);
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L->top++; /* keep it in stack to avoid being (recursively) collected */
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callgcTM(L, L->top-1);
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uvalue(L->top-1)->uv.tag = 0; /* default tag (udata is `finalized') */
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L->top--;
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}
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}
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}
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void luaC_callallgcTM (lua_State *L) {
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if (G(L)->rootudata) { /* avoid problems with incomplete states */
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collectudata(L, 1); /* collect all udata into tag lists */
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callgcTMudata(L); /* call their GC tag methods */
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}
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}
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void luaC_collect (lua_State *L, int all) {
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collectudata(L, 0);
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collectstrings(L, all);
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collecttable(L);
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collectproto(L);
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collectclosure(L);
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}
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void luaC_collectgarbage (lua_State *L) {
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markall(L);
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cleartables(G(L));
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luaC_collect(L, 0);
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checkMbuffer(L);
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G(L)->GCthreshold = 2*G(L)->nblocks; /* new threshold */
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callgcTMudata(L);
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callgcTM(L, &luaO_nilobject);
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}
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