diff options
Diffstat (limited to 'lib/lua/src/lgc.c')
| -rw-r--r-- | lib/lua/src/lgc.c | 493 |
1 files changed, 493 insertions, 0 deletions
diff --git a/lib/lua/src/lgc.c b/lib/lua/src/lgc.c new file mode 100644 index 0000000..116fb69 --- /dev/null +++ b/lib/lua/src/lgc.c @@ -0,0 +1,493 @@ +/*
+** $Id: lgc.c,v 1.1 2003-11-06 11:56:07 pixel Exp $
+** Garbage Collector
+** See Copyright Notice in lua.h
+*/
+
+#include <string.h>
+
+#define lgc_c
+
+#include "lua.h"
+
+#include "ldebug.h"
+#include "ldo.h"
+#include "lfunc.h"
+#include "lgc.h"
+#include "lmem.h"
+#include "lobject.h"
+#include "lstate.h"
+#include "lstring.h"
+#include "ltable.h"
+#include "ltm.h"
+
+
+typedef struct GCState {
+ GCObject *tmark; /* list of marked objects to be traversed */
+ GCObject *wk; /* list of traversed key-weak tables (to be cleared) */
+ GCObject *wv; /* list of traversed value-weak tables */
+ GCObject *wkv; /* list of traversed key-value weak tables */
+ global_State *g;
+} GCState;
+
+
+/*
+** some userful bit tricks
+*/
+#define setbit(x,b) ((x) |= (1<<(b)))
+#define resetbit(x,b) ((x) &= cast(lu_byte, ~(1<<(b))))
+#define testbit(x,b) ((x) & (1<<(b)))
+
+#define unmark(x) resetbit((x)->gch.marked, 0)
+#define ismarked(x) ((x)->gch.marked & ((1<<4)|1))
+
+#define stringmark(s) setbit((s)->tsv.marked, 0)
+
+
+#define isfinalized(u) (!testbit((u)->uv.marked, 1))
+#define markfinalized(u) resetbit((u)->uv.marked, 1)
+
+
+#define KEYWEAKBIT 1
+#define VALUEWEAKBIT 2
+#define KEYWEAK (1<<KEYWEAKBIT)
+#define VALUEWEAK (1<<VALUEWEAKBIT)
+
+
+
+#define markobject(st,o) { checkconsistency(o); \
+ if (iscollectable(o) && !ismarked(gcvalue(o))) reallymarkobject(st,gcvalue(o)); }
+
+#define condmarkobject(st,o,c) { checkconsistency(o); \
+ if (iscollectable(o) && !ismarked(gcvalue(o)) && (c)) \
+ reallymarkobject(st,gcvalue(o)); }
+
+#define markvalue(st,t) { if (!ismarked(valtogco(t))) \
+ reallymarkobject(st, valtogco(t)); }
+
+
+
+static void reallymarkobject (GCState *st, GCObject *o) {
+ lua_assert(!ismarked(o));
+ setbit(o->gch.marked, 0); /* mark object */
+ switch (o->gch.tt) {
+ case LUA_TUSERDATA: {
+ markvalue(st, gcotou(o)->uv.metatable);
+ break;
+ }
+ case LUA_TFUNCTION: {
+ gcotocl(o)->c.gclist = st->tmark;
+ st->tmark = o;
+ break;
+ }
+ case LUA_TTABLE: {
+ gcotoh(o)->gclist = st->tmark;
+ st->tmark = o;
+ break;
+ }
+ case LUA_TTHREAD: {
+ gcototh(o)->gclist = st->tmark;
+ st->tmark = o;
+ break;
+ }
+ case LUA_TPROTO: {
+ gcotop(o)->gclist = st->tmark;
+ st->tmark = o;
+ break;
+ }
+ default: lua_assert(o->gch.tt == LUA_TSTRING);
+ }
+}
+
+
+static void marktmu (GCState *st) {
+ GCObject *u;
+ for (u = st->g->tmudata; u; u = u->gch.next) {
+ unmark(u); /* may be marked, if left from previous GC */
+ reallymarkobject(st, u);
+ }
+}
+
+
+/* move `dead' udata that need finalization to list `tmudata' */
+void luaC_separateudata (lua_State *L) {
+ GCObject **p = &G(L)->rootudata;
+ GCObject *curr;
+ GCObject *collected = NULL; /* to collect udata with gc event */
+ GCObject **lastcollected = &collected;
+ while ((curr = *p) != NULL) {
+ lua_assert(curr->gch.tt == LUA_TUSERDATA);
+ if (ismarked(curr) || isfinalized(gcotou(curr)))
+ p = &curr->gch.next; /* don't bother with them */
+
+ else if (fasttm(L, gcotou(curr)->uv.metatable, TM_GC) == NULL) {
+ markfinalized(gcotou(curr)); /* don't need finalization */
+ p = &curr->gch.next;
+ }
+ else { /* must call its gc method */
+ *p = curr->gch.next;
+ curr->gch.next = NULL; /* link `curr' at the end of `collected' list */
+ *lastcollected = curr;
+ lastcollected = &curr->gch.next;
+ }
+ }
+ /* insert collected udata with gc event into `tmudata' list */
+ *lastcollected = G(L)->tmudata;
+ G(L)->tmudata = collected;
+}
+
+
+static void removekey (Node *n) {
+ setnilvalue(gval(n)); /* remove corresponding value ... */
+ if (iscollectable(gkey(n)))
+ setttype(gkey(n), LUA_TNONE); /* dead key; remove it */
+}
+
+
+static void traversetable (GCState *st, Table *h) {
+ int i;
+ int weakkey = 0;
+ int weakvalue = 0;
+ const TObject *mode;
+ markvalue(st, h->metatable);
+ lua_assert(h->lsizenode || h->node == st->g->dummynode);
+ mode = gfasttm(st->g, h->metatable, TM_MODE);
+ if (mode && ttisstring(mode)) { /* is there a weak mode? */
+ weakkey = (strchr(svalue(mode), 'k') != NULL);
+ weakvalue = (strchr(svalue(mode), 'v') != NULL);
+ if (weakkey || weakvalue) { /* is really weak? */
+ GCObject **weaklist;
+ h->marked &= ~(KEYWEAK | VALUEWEAK); /* clear bits */
+ h->marked |= cast(lu_byte, (weakkey << KEYWEAKBIT) |
+ (weakvalue << VALUEWEAKBIT));
+ weaklist = (weakkey && weakvalue) ? &st->wkv :
+ (weakkey) ? &st->wk :
+ &st->wv;
+ h->gclist = *weaklist; /* must be cleared after GC, ... */
+ *weaklist = valtogco(h); /* ... so put in the appropriate list */
+ }
+ }
+ if (!weakvalue) {
+ i = h->sizearray;
+ while (i--)
+ markobject(st, &h->array[i]);
+ }
+ i = sizenode(h);
+ while (i--) {
+ Node *n = gnode(h, i);
+ if (!ttisnil(gval(n))) {
+ lua_assert(!ttisnil(gkey(n)));
+ condmarkobject(st, gkey(n), !weakkey);
+ condmarkobject(st, gval(n), !weakvalue);
+ }
+ }
+}
+
+
+static void traverseproto (GCState *st, Proto *f) {
+ int i;
+ stringmark(f->source);
+ for (i=0; i<f->sizek; i++) { /* mark literal strings */
+ if (ttisstring(f->k+i))
+ stringmark(tsvalue(f->k+i));
+ }
+ for (i=0; i<f->sizeupvalues; i++) /* mark upvalue names */
+ stringmark(f->upvalues[i]);
+ for (i=0; i<f->sizep; i++) /* mark nested protos */
+ markvalue(st, f->p[i]);
+ for (i=0; i<f->sizelocvars; i++) /* mark local-variable names */
+ stringmark(f->locvars[i].varname);
+ lua_assert(luaG_checkcode(f));
+}
+
+
+
+static void traverseclosure (GCState *st, Closure *cl) {
+ if (cl->c.isC) {
+ int i;
+ for (i=0; i<cl->c.nupvalues; i++) /* mark its upvalues */
+ markobject(st, &cl->c.upvalue[i]);
+ }
+ else {
+ int i;
+ lua_assert(cl->l.nupvalues == cl->l.p->nups);
+ markvalue(st, hvalue(&cl->l.g));
+ markvalue(st, cl->l.p);
+ for (i=0; i<cl->l.nupvalues; i++) { /* mark its upvalues */
+ UpVal *u = cl->l.upvals[i];
+ if (!u->marked) {
+ markobject(st, &u->value);
+ u->marked = 1;
+ }
+ }
+ }
+}
+
+
+static void checkstacksizes (lua_State *L, StkId max) {
+ int used = L->ci - L->base_ci; /* number of `ci' in use */
+ if (4*used < L->size_ci && 2*BASIC_CI_SIZE < L->size_ci)
+ luaD_reallocCI(L, L->size_ci/2); /* still big enough... */
+ else condhardstacktests(luaD_reallocCI(L, L->size_ci));
+ used = max - L->stack; /* part of stack in use */
+ if (4*used < L->stacksize && 2*(BASIC_STACK_SIZE+EXTRA_STACK) < L->stacksize)
+ luaD_reallocstack(L, L->stacksize/2); /* still big enough... */
+ else condhardstacktests(luaD_reallocstack(L, L->stacksize));
+}
+
+
+static void traversestack (GCState *st, lua_State *L1) {
+ StkId o, lim;
+ CallInfo *ci;
+ markobject(st, gt(L1));
+ lim = L1->top;
+ for (ci = L1->base_ci; ci <= L1->ci; ci++) {
+ lua_assert(ci->top <= L1->stack_last);
+ lua_assert(ci->state & (CI_C | CI_HASFRAME | CI_SAVEDPC));
+ if (!(ci->state & CI_C) && lim < ci->top)
+ lim = ci->top;
+ }
+ for (o = L1->stack; o < L1->top; o++)
+ markobject(st, o);
+ for (; o <= lim; o++)
+ setnilvalue(o);
+ checkstacksizes(L1, lim);
+}
+
+
+static void propagatemarks (GCState *st) {
+ while (st->tmark) { /* traverse marked objects */
+ switch (st->tmark->gch.tt) {
+ case LUA_TTABLE: {
+ Table *h = gcotoh(st->tmark);
+ st->tmark = h->gclist;
+ traversetable(st, h);
+ break;
+ }
+ case LUA_TFUNCTION: {
+ Closure *cl = gcotocl(st->tmark);
+ st->tmark = cl->c.gclist;
+ traverseclosure(st, cl);
+ break;
+ }
+ case LUA_TTHREAD: {
+ lua_State *th = gcototh(st->tmark);
+ st->tmark = th->gclist;
+ traversestack(st, th);
+ break;
+ }
+ case LUA_TPROTO: {
+ Proto *p = gcotop(st->tmark);
+ st->tmark = p->gclist;
+ traverseproto(st, p);
+ break;
+ }
+ default: lua_assert(0);
+ }
+ }
+}
+
+
+static int valismarked (const TObject *o) {
+ if (ttisstring(o))
+ stringmark(tsvalue(o)); /* strings are `values', so are never weak */
+ return !iscollectable(o) || testbit(o->value.gc->gch.marked, 0);
+}
+
+
+/*
+** clear collected keys from weaktables
+*/
+static void cleartablekeys (GCObject *l) {
+ while (l) {
+ Table *h = gcotoh(l);
+ int i = sizenode(h);
+ lua_assert(h->marked & KEYWEAK);
+ while (i--) {
+ Node *n = gnode(h, i);
+ if (!valismarked(gkey(n))) /* key was collected? */
+ removekey(n); /* remove entry from table */
+ }
+ l = h->gclist;
+ }
+}
+
+
+/*
+** clear collected values from weaktables
+*/
+static void cleartablevalues (GCObject *l) {
+ while (l) {
+ Table *h = gcotoh(l);
+ int i = h->sizearray;
+ lua_assert(h->marked & VALUEWEAK);
+ while (i--) {
+ TObject *o = &h->array[i];
+ if (!valismarked(o)) /* value was collected? */
+ setnilvalue(o); /* remove value */
+ }
+ i = sizenode(h);
+ while (i--) {
+ Node *n = gnode(h, i);
+ if (!valismarked(gval(n))) /* value was collected? */
+ removekey(n); /* remove entry from table */
+ }
+ l = h->gclist;
+ }
+}
+
+
+static void freeobj (lua_State *L, GCObject *o) {
+ switch (o->gch.tt) {
+ case LUA_TPROTO: luaF_freeproto(L, gcotop(o)); break;
+ case LUA_TFUNCTION: luaF_freeclosure(L, gcotocl(o)); break;
+ case LUA_TUPVAL: luaM_freelem(L, gcotouv(o)); break;
+ case LUA_TTABLE: luaH_free(L, gcotoh(o)); break;
+ case LUA_TTHREAD: {
+ lua_assert(gcototh(o) != L && gcototh(o) != G(L)->mainthread);
+ luaE_freethread(L, gcototh(o));
+ break;
+ }
+ case LUA_TSTRING: {
+ luaM_free(L, o, sizestring(gcotots(o)->tsv.len));
+ break;
+ }
+ case LUA_TUSERDATA: {
+ luaM_free(L, o, sizeudata(gcotou(o)->uv.len));
+ break;
+ }
+ default: lua_assert(0);
+ }
+}
+
+
+static int sweeplist (lua_State *L, GCObject **p, int limit) {
+ GCObject *curr;
+ int count = 0; /* number of collected items */
+ while ((curr = *p) != NULL) {
+ if (curr->gch.marked > limit) {
+ unmark(curr);
+ p = &curr->gch.next;
+ }
+ else {
+ count++;
+ *p = curr->gch.next;
+ freeobj(L, curr);
+ }
+ }
+ return count;
+}
+
+
+static void sweepstrings (lua_State *L, int all) {
+ int i;
+ for (i=0; i<G(L)->strt.size; i++) { /* for each list */
+ G(L)->strt.nuse -= sweeplist(L, &G(L)->strt.hash[i], all);
+ }
+}
+
+
+static void checkSizes (lua_State *L) {
+ /* check size of string hash */
+ if (G(L)->strt.nuse < cast(ls_nstr, G(L)->strt.size/4) &&
+ G(L)->strt.size > MINSTRTABSIZE*2)
+ luaS_resize(L, G(L)->strt.size/2); /* table is too big */
+ /* check size of buffer */
+ if (luaZ_sizebuffer(&G(L)->buff) > LUA_MINBUFFER*2) { /* buffer too big? */
+ size_t newsize = luaZ_sizebuffer(&G(L)->buff) / 2;
+ luaZ_resizebuffer(L, &G(L)->buff, newsize);
+ }
+ G(L)->GCthreshold = 2*G(L)->nblocks; /* new threshold */
+}
+
+
+static void do1gcTM (lua_State *L, Udata *udata) {
+ const TObject *tm = fasttm(L, udata->uv.metatable, TM_GC);
+ if (tm != NULL) {
+ setobj2s(L->top, tm);
+ setuvalue(L->top+1, udata);
+ L->top += 2;
+ luaD_call(L, L->top - 2, 0);
+ }
+}
+
+
+void luaC_callGCTM (lua_State *L) {
+ lu_byte oldah = L->allowhook;
+ L->allowhook = 0; /* stop debug hooks during GC tag methods */
+ L->top++; /* reserve space to keep udata while runs its gc method */
+ while (G(L)->tmudata != NULL) {
+ GCObject *o = G(L)->tmudata;
+ Udata *udata = gcotou(o);
+ G(L)->tmudata = udata->uv.next; /* remove udata from `tmudata' */
+ udata->uv.next = G(L)->rootudata; /* return it to `root' list */
+ G(L)->rootudata = o;
+ setuvalue(L->top - 1, udata); /* keep a reference to it */
+ unmark(o);
+ markfinalized(udata);
+ do1gcTM(L, udata);
+ }
+ L->top--;
+ L->allowhook = oldah; /* restore hooks */
+}
+
+
+void luaC_sweep (lua_State *L, int all) {
+ if (all) all = 256; /* larger than any mark */
+ sweeplist(L, &G(L)->rootudata, all);
+ sweepstrings(L, all);
+ sweeplist(L, &G(L)->rootgc, all);
+}
+
+
+/* mark root set */
+static void markroot (GCState *st, lua_State *L) {
+ global_State *g = st->g;
+ markobject(st, defaultmeta(L));
+ markobject(st, registry(L));
+ traversestack(st, g->mainthread);
+ if (L != g->mainthread) /* another thread is running? */
+ markvalue(st, L); /* cannot collect it */
+}
+
+
+static void mark (lua_State *L) {
+ GCState st;
+ GCObject *wkv;
+ st.g = G(L);
+ st.tmark = NULL;
+ st.wkv = st.wk = st.wv = NULL;
+ markroot(&st, L);
+ propagatemarks(&st); /* mark all reachable objects */
+ cleartablevalues(st.wkv);
+ cleartablevalues(st.wv);
+ wkv = st.wkv; /* keys must be cleared after preserving udata */
+ st.wkv = NULL;
+ st.wv = NULL;
+ luaC_separateudata(L); /* separate userdata to be preserved */
+ marktmu(&st); /* mark `preserved' userdata */
+ propagatemarks(&st); /* remark, to propagate `preserveness' */
+ cleartablekeys(wkv);
+ /* `propagatemarks' may resuscitate some weak tables; clear them too */
+ cleartablekeys(st.wk);
+ cleartablevalues(st.wv);
+ cleartablekeys(st.wkv);
+ cleartablevalues(st.wkv);
+}
+
+
+void luaC_collectgarbage (lua_State *L) {
+ mark(L);
+ luaC_sweep(L, 0);
+ checkSizes(L);
+ luaC_callGCTM(L);
+}
+
+
+void luaC_link (lua_State *L, GCObject *o, lu_byte tt) {
+ o->gch.next = G(L)->rootgc;
+ G(L)->rootgc = o;
+ o->gch.marked = 0;
+ o->gch.tt = tt;
+}
+
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