summaryrefslogtreecommitdiffstats
path: root/apps/plugins/lua/lgc.c
diff options
context:
space:
mode:
authorMaurus Cuelenaere <mcuelenaere@gmail.com>2009-05-21 19:01:41 +0000
committerMaurus Cuelenaere <mcuelenaere@gmail.com>2009-05-21 19:01:41 +0000
commitcf87597226f5d6b269f1f2c4d6f402aa1eccb852 (patch)
tree4ba1f3ae53b3bd9cae0e2c6c4dd57836b43a5ece /apps/plugins/lua/lgc.c
parentc483efadc63eaed35b5fb5e4e02c2282daf32470 (diff)
downloadrockbox-cf87597226f5d6b269f1f2c4d6f402aa1eccb852.tar.gz
rockbox-cf87597226f5d6b269f1f2c4d6f402aa1eccb852.tar.bz2
rockbox-cf87597226f5d6b269f1f2c4d6f402aa1eccb852.zip
Commit FS#9174: Lua scripting language by Dan Everton
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@21020 a1c6a512-1295-4272-9138-f99709370657
Diffstat (limited to 'apps/plugins/lua/lgc.c')
-rw-r--r--apps/plugins/lua/lgc.c711
1 files changed, 711 insertions, 0 deletions
diff --git a/apps/plugins/lua/lgc.c b/apps/plugins/lua/lgc.c
new file mode 100644
index 0000000000..d9e0b78294
--- /dev/null
+++ b/apps/plugins/lua/lgc.c
@@ -0,0 +1,711 @@
+/*
+** $Id: lgc.c,v 2.38.1.1 2007/12/27 13:02:25 roberto Exp $
+** Garbage Collector
+** See Copyright Notice in lua.h
+*/
+
+#include <string.h>
+
+#define lgc_c
+#define LUA_CORE
+
+#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"
+
+
+#define GCSTEPSIZE 1024u
+#define GCSWEEPMAX 40
+#define GCSWEEPCOST 10
+#define GCFINALIZECOST 100
+
+
+#define maskmarks cast_byte(~(bitmask(BLACKBIT)|WHITEBITS))
+
+#define makewhite(g,x) \
+ ((x)->gch.marked = cast_byte(((x)->gch.marked & maskmarks) | luaC_white(g)))
+
+#define white2gray(x) reset2bits((x)->gch.marked, WHITE0BIT, WHITE1BIT)
+#define black2gray(x) resetbit((x)->gch.marked, BLACKBIT)
+
+#define stringmark(s) reset2bits((s)->tsv.marked, WHITE0BIT, WHITE1BIT)
+
+
+#define isfinalized(u) testbit((u)->marked, FINALIZEDBIT)
+#define markfinalized(u) l_setbit((u)->marked, FINALIZEDBIT)
+
+
+#define KEYWEAK bitmask(KEYWEAKBIT)
+#define VALUEWEAK bitmask(VALUEWEAKBIT)
+
+
+
+#define markvalue(g,o) { checkconsistency(o); \
+ if (iscollectable(o) && iswhite(gcvalue(o))) reallymarkobject(g,gcvalue(o)); }
+
+#define markobject(g,t) { if (iswhite(obj2gco(t))) \
+ reallymarkobject(g, obj2gco(t)); }
+
+
+#define setthreshold(g) (g->GCthreshold = (g->estimate/100) * g->gcpause)
+
+
+static void removeentry (Node *n) {
+ lua_assert(ttisnil(gval(n)));
+ if (iscollectable(gkey(n)))
+ setttype(gkey(n), LUA_TDEADKEY); /* dead key; remove it */
+}
+
+
+static void reallymarkobject (global_State *g, GCObject *o) {
+ lua_assert(iswhite(o) && !isdead(g, o));
+ white2gray(o);
+ switch (o->gch.tt) {
+ case LUA_TSTRING: {
+ return;
+ }
+ case LUA_TUSERDATA: {
+ Table *mt = gco2u(o)->metatable;
+ gray2black(o); /* udata are never gray */
+ if (mt) markobject(g, mt);
+ markobject(g, gco2u(o)->env);
+ return;
+ }
+ case LUA_TUPVAL: {
+ UpVal *uv = gco2uv(o);
+ markvalue(g, uv->v);
+ if (uv->v == &uv->u.value) /* closed? */
+ gray2black(o); /* open upvalues are never black */
+ return;
+ }
+ case LUA_TFUNCTION: {
+ gco2cl(o)->c.gclist = g->gray;
+ g->gray = o;
+ break;
+ }
+ case LUA_TTABLE: {
+ gco2h(o)->gclist = g->gray;
+ g->gray = o;
+ break;
+ }
+ case LUA_TTHREAD: {
+ gco2th(o)->gclist = g->gray;
+ g->gray = o;
+ break;
+ }
+ case LUA_TPROTO: {
+ gco2p(o)->gclist = g->gray;
+ g->gray = o;
+ break;
+ }
+ default: lua_assert(0);
+ }
+}
+
+
+static void marktmu (global_State *g) {
+ GCObject *u = g->tmudata;
+ if (u) {
+ do {
+ u = u->gch.next;
+ makewhite(g, u); /* may be marked, if left from previous GC */
+ reallymarkobject(g, u);
+ } while (u != g->tmudata);
+ }
+}
+
+
+/* move `dead' udata that need finalization to list `tmudata' */
+size_t luaC_separateudata (lua_State *L, int all) {
+ global_State *g = G(L);
+ size_t deadmem = 0;
+ GCObject **p = &g->mainthread->next;
+ GCObject *curr;
+ while ((curr = *p) != NULL) {
+ if (!(iswhite(curr) || all) || isfinalized(gco2u(curr)))
+ p = &curr->gch.next; /* don't bother with them */
+ else if (fasttm(L, gco2u(curr)->metatable, TM_GC) == NULL) {
+ markfinalized(gco2u(curr)); /* don't need finalization */
+ p = &curr->gch.next;
+ }
+ else { /* must call its gc method */
+ deadmem += sizeudata(gco2u(curr));
+ markfinalized(gco2u(curr));
+ *p = curr->gch.next;
+ /* link `curr' at the end of `tmudata' list */
+ if (g->tmudata == NULL) /* list is empty? */
+ g->tmudata = curr->gch.next = curr; /* creates a circular list */
+ else {
+ curr->gch.next = g->tmudata->gch.next;
+ g->tmudata->gch.next = curr;
+ g->tmudata = curr;
+ }
+ }
+ }
+ return deadmem;
+}
+
+
+static int traversetable (global_State *g, Table *h) {
+ int i;
+ int weakkey = 0;
+ int weakvalue = 0;
+ const TValue *mode;
+ if (h->metatable)
+ markobject(g, h->metatable);
+ mode = gfasttm(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? */
+ h->marked &= ~(KEYWEAK | VALUEWEAK); /* clear bits */
+ h->marked |= cast_byte((weakkey << KEYWEAKBIT) |
+ (weakvalue << VALUEWEAKBIT));
+ h->gclist = g->weak; /* must be cleared after GC, ... */
+ g->weak = obj2gco(h); /* ... so put in the appropriate list */
+ }
+ }
+ if (weakkey && weakvalue) return 1;
+ if (!weakvalue) {
+ i = h->sizearray;
+ while (i--)
+ markvalue(g, &h->array[i]);
+ }
+ i = sizenode(h);
+ while (i--) {
+ Node *n = gnode(h, i);
+ lua_assert(ttype(gkey(n)) != LUA_TDEADKEY || ttisnil(gval(n)));
+ if (ttisnil(gval(n)))
+ removeentry(n); /* remove empty entries */
+ else {
+ lua_assert(!ttisnil(gkey(n)));
+ if (!weakkey) markvalue(g, gkey(n));
+ if (!weakvalue) markvalue(g, gval(n));
+ }
+ }
+ return weakkey || weakvalue;
+}
+
+
+/*
+** All marks are conditional because a GC may happen while the
+** prototype is still being created
+*/
+static void traverseproto (global_State *g, Proto *f) {
+ int i;
+ if (f->source) stringmark(f->source);
+ for (i=0; i<f->sizek; i++) /* mark literals */
+ markvalue(g, &f->k[i]);
+ for (i=0; i<f->sizeupvalues; i++) { /* mark upvalue names */
+ if (f->upvalues[i])
+ stringmark(f->upvalues[i]);
+ }
+ for (i=0; i<f->sizep; i++) { /* mark nested protos */
+ if (f->p[i])
+ markobject(g, f->p[i]);
+ }
+ for (i=0; i<f->sizelocvars; i++) { /* mark local-variable names */
+ if (f->locvars[i].varname)
+ stringmark(f->locvars[i].varname);
+ }
+}
+
+
+
+static void traverseclosure (global_State *g, Closure *cl) {
+ markobject(g, cl->c.env);
+ if (cl->c.isC) {
+ int i;
+ for (i=0; i<cl->c.nupvalues; i++) /* mark its upvalues */
+ markvalue(g, &cl->c.upvalue[i]);
+ }
+ else {
+ int i;
+ lua_assert(cl->l.nupvalues == cl->l.p->nups);
+ markobject(g, cl->l.p);
+ for (i=0; i<cl->l.nupvalues; i++) /* mark its upvalues */
+ markobject(g, cl->l.upvals[i]);
+ }
+}
+
+
+static void checkstacksizes (lua_State *L, StkId max) {
+ int ci_used = cast_int(L->ci - L->base_ci); /* number of `ci' in use */
+ int s_used = cast_int(max - L->stack); /* part of stack in use */
+ if (L->size_ci > LUAI_MAXCALLS) /* handling overflow? */
+ return; /* do not touch the stacks */
+ if (4*ci_used < L->size_ci && 2*BASIC_CI_SIZE < L->size_ci)
+ luaD_reallocCI(L, L->size_ci/2); /* still big enough... */
+ condhardstacktests(luaD_reallocCI(L, ci_used + 1));
+ if (4*s_used < L->stacksize &&
+ 2*(BASIC_STACK_SIZE+EXTRA_STACK) < L->stacksize)
+ luaD_reallocstack(L, L->stacksize/2); /* still big enough... */
+ condhardstacktests(luaD_reallocstack(L, s_used));
+}
+
+
+static void traversestack (global_State *g, lua_State *l) {
+ StkId o, lim;
+ CallInfo *ci;
+ markvalue(g, gt(l));
+ lim = l->top;
+ for (ci = l->base_ci; ci <= l->ci; ci++) {
+ lua_assert(ci->top <= l->stack_last);
+ if (lim < ci->top) lim = ci->top;
+ }
+ for (o = l->stack; o < l->top; o++)
+ markvalue(g, o);
+ for (; o <= lim; o++)
+ setnilvalue(o);
+ checkstacksizes(l, lim);
+}
+
+
+/*
+** traverse one gray object, turning it to black.
+** Returns `quantity' traversed.
+*/
+static l_mem propagatemark (global_State *g) {
+ GCObject *o = g->gray;
+ lua_assert(isgray(o));
+ gray2black(o);
+ switch (o->gch.tt) {
+ case LUA_TTABLE: {
+ Table *h = gco2h(o);
+ g->gray = h->gclist;
+ if (traversetable(g, h)) /* table is weak? */
+ black2gray(o); /* keep it gray */
+ return sizeof(Table) + sizeof(TValue) * h->sizearray +
+ sizeof(Node) * sizenode(h);
+ }
+ case LUA_TFUNCTION: {
+ Closure *cl = gco2cl(o);
+ g->gray = cl->c.gclist;
+ traverseclosure(g, cl);
+ return (cl->c.isC) ? sizeCclosure(cl->c.nupvalues) :
+ sizeLclosure(cl->l.nupvalues);
+ }
+ case LUA_TTHREAD: {
+ lua_State *th = gco2th(o);
+ g->gray = th->gclist;
+ th->gclist = g->grayagain;
+ g->grayagain = o;
+ black2gray(o);
+ traversestack(g, th);
+ return sizeof(lua_State) + sizeof(TValue) * th->stacksize +
+ sizeof(CallInfo) * th->size_ci;
+ }
+ case LUA_TPROTO: {
+ Proto *p = gco2p(o);
+ g->gray = p->gclist;
+ traverseproto(g, p);
+ return sizeof(Proto) + sizeof(Instruction) * p->sizecode +
+ sizeof(Proto *) * p->sizep +
+ sizeof(TValue) * p->sizek +
+ sizeof(int) * p->sizelineinfo +
+ sizeof(LocVar) * p->sizelocvars +
+ sizeof(TString *) * p->sizeupvalues;
+ }
+ default: lua_assert(0); return 0;
+ }
+}
+
+
+static size_t propagateall (global_State *g) {
+ size_t m = 0;
+ while (g->gray) m += propagatemark(g);
+ return m;
+}
+
+
+/*
+** The next function tells whether a key or value can be cleared from
+** a weak table. Non-collectable objects are never removed from weak
+** tables. Strings behave as `values', so are never removed too. for
+** other objects: if really collected, cannot keep them; for userdata
+** being finalized, keep them in keys, but not in values
+*/
+static int iscleared (const TValue *o, int iskey) {
+ if (!iscollectable(o)) return 0;
+ if (ttisstring(o)) {
+ stringmark(rawtsvalue(o)); /* strings are `values', so are never weak */
+ return 0;
+ }
+ return iswhite(gcvalue(o)) ||
+ (ttisuserdata(o) && (!iskey && isfinalized(uvalue(o))));
+}
+
+
+/*
+** clear collected entries from weaktables
+*/
+static void cleartable (GCObject *l) {
+ while (l) {
+ Table *h = gco2h(l);
+ int i = h->sizearray;
+ lua_assert(testbit(h->marked, VALUEWEAKBIT) ||
+ testbit(h->marked, KEYWEAKBIT));
+ if (testbit(h->marked, VALUEWEAKBIT)) {
+ while (i--) {
+ TValue *o = &h->array[i];
+ if (iscleared(o, 0)) /* value was collected? */
+ setnilvalue(o); /* remove value */
+ }
+ }
+ i = sizenode(h);
+ while (i--) {
+ Node *n = gnode(h, i);
+ if (!ttisnil(gval(n)) && /* non-empty entry? */
+ (iscleared(key2tval(n), 1) || iscleared(gval(n), 0))) {
+ setnilvalue(gval(n)); /* remove value ... */
+ removeentry(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, gco2p(o)); break;
+ case LUA_TFUNCTION: luaF_freeclosure(L, gco2cl(o)); break;
+ case LUA_TUPVAL: luaF_freeupval(L, gco2uv(o)); break;
+ case LUA_TTABLE: luaH_free(L, gco2h(o)); break;
+ case LUA_TTHREAD: {
+ lua_assert(gco2th(o) != L && gco2th(o) != G(L)->mainthread);
+ luaE_freethread(L, gco2th(o));
+ break;
+ }
+ case LUA_TSTRING: {
+ G(L)->strt.nuse--;
+ luaM_freemem(L, o, sizestring(gco2ts(o)));
+ break;
+ }
+ case LUA_TUSERDATA: {
+ luaM_freemem(L, o, sizeudata(gco2u(o)));
+ break;
+ }
+ default: lua_assert(0);
+ }
+}
+
+
+
+#define sweepwholelist(L,p) sweeplist(L,p,MAX_LUMEM)
+
+
+static GCObject **sweeplist (lua_State *L, GCObject **p, lu_mem count) {
+ GCObject *curr;
+ global_State *g = G(L);
+ int deadmask = otherwhite(g);
+ while ((curr = *p) != NULL && count-- > 0) {
+ if (curr->gch.tt == LUA_TTHREAD) /* sweep open upvalues of each thread */
+ sweepwholelist(L, &gco2th(curr)->openupval);
+ if ((curr->gch.marked ^ WHITEBITS) & deadmask) { /* not dead? */
+ lua_assert(!isdead(g, curr) || testbit(curr->gch.marked, FIXEDBIT));
+ makewhite(g, curr); /* make it white (for next cycle) */
+ p = &curr->gch.next;
+ }
+ else { /* must erase `curr' */
+ lua_assert(isdead(g, curr) || deadmask == bitmask(SFIXEDBIT));
+ *p = curr->gch.next;
+ if (curr == g->rootgc) /* is the first element of the list? */
+ g->rootgc = curr->gch.next; /* adjust first */
+ freeobj(L, curr);
+ }
+ }
+ return p;
+}
+
+
+static void checkSizes (lua_State *L) {
+ global_State *g = G(L);
+ /* check size of string hash */
+ if (g->strt.nuse < cast(lu_int32, g->strt.size/4) &&
+ g->strt.size > MINSTRTABSIZE*2)
+ luaS_resize(L, g->strt.size/2); /* table is too big */
+ /* check size of buffer */
+ if (luaZ_sizebuffer(&g->buff) > LUA_MINBUFFER*2) { /* buffer too big? */
+ size_t newsize = luaZ_sizebuffer(&g->buff) / 2;
+ luaZ_resizebuffer(L, &g->buff, newsize);
+ }
+}
+
+
+static void GCTM (lua_State *L) {
+ global_State *g = G(L);
+ GCObject *o = g->tmudata->gch.next; /* get first element */
+ Udata *udata = rawgco2u(o);
+ const TValue *tm;
+ /* remove udata from `tmudata' */
+ if (o == g->tmudata) /* last element? */
+ g->tmudata = NULL;
+ else
+ g->tmudata->gch.next = udata->uv.next;
+ udata->uv.next = g->mainthread->next; /* return it to `root' list */
+ g->mainthread->next = o;
+ makewhite(g, o);
+ tm = fasttm(L, udata->uv.metatable, TM_GC);
+ if (tm != NULL) {
+ lu_byte oldah = L->allowhook;
+ lu_mem oldt = g->GCthreshold;
+ L->allowhook = 0; /* stop debug hooks during GC tag method */
+ g->GCthreshold = 2*g->totalbytes; /* avoid GC steps */
+ setobj2s(L, L->top, tm);
+ setuvalue(L, L->top+1, udata);
+ L->top += 2;
+ luaD_call(L, L->top - 2, 0);
+ L->allowhook = oldah; /* restore hooks */
+ g->GCthreshold = oldt; /* restore threshold */
+ }
+}
+
+
+/*
+** Call all GC tag methods
+*/
+void luaC_callGCTM (lua_State *L) {
+ while (G(L)->tmudata)
+ GCTM(L);
+}
+
+
+void luaC_freeall (lua_State *L) {
+ global_State *g = G(L);
+ int i;
+ g->currentwhite = WHITEBITS | bitmask(SFIXEDBIT); /* mask to collect all elements */
+ sweepwholelist(L, &g->rootgc);
+ for (i = 0; i < g->strt.size; i++) /* free all string lists */
+ sweepwholelist(L, &g->strt.hash[i]);
+}
+
+
+static void markmt (global_State *g) {
+ int i;
+ for (i=0; i<NUM_TAGS; i++)
+ if (g->mt[i]) markobject(g, g->mt[i]);
+}
+
+
+/* mark root set */
+static void markroot (lua_State *L) {
+ global_State *g = G(L);
+ g->gray = NULL;
+ g->grayagain = NULL;
+ g->weak = NULL;
+ markobject(g, g->mainthread);
+ /* make global table be traversed before main stack */
+ markvalue(g, gt(g->mainthread));
+ markvalue(g, registry(L));
+ markmt(g);
+ g->gcstate = GCSpropagate;
+}
+
+
+static void remarkupvals (global_State *g) {
+ UpVal *uv;
+ for (uv = g->uvhead.u.l.next; uv != &g->uvhead; uv = uv->u.l.next) {
+ lua_assert(uv->u.l.next->u.l.prev == uv && uv->u.l.prev->u.l.next == uv);
+ if (isgray(obj2gco(uv)))
+ markvalue(g, uv->v);
+ }
+}
+
+
+static void atomic (lua_State *L) {
+ global_State *g = G(L);
+ size_t udsize; /* total size of userdata to be finalized */
+ /* remark occasional upvalues of (maybe) dead threads */
+ remarkupvals(g);
+ /* traverse objects cautch by write barrier and by 'remarkupvals' */
+ propagateall(g);
+ /* remark weak tables */
+ g->gray = g->weak;
+ g->weak = NULL;
+ lua_assert(!iswhite(obj2gco(g->mainthread)));
+ markobject(g, L); /* mark running thread */
+ markmt(g); /* mark basic metatables (again) */
+ propagateall(g);
+ /* remark gray again */
+ g->gray = g->grayagain;
+ g->grayagain = NULL;
+ propagateall(g);
+ udsize = luaC_separateudata(L, 0); /* separate userdata to be finalized */
+ marktmu(g); /* mark `preserved' userdata */
+ udsize += propagateall(g); /* remark, to propagate `preserveness' */
+ cleartable(g->weak); /* remove collected objects from weak tables */
+ /* flip current white */
+ g->currentwhite = cast_byte(otherwhite(g));
+ g->sweepstrgc = 0;
+ g->sweepgc = &g->rootgc;
+ g->gcstate = GCSsweepstring;
+ g->estimate = g->totalbytes - udsize; /* first estimate */
+}
+
+
+static l_mem singlestep (lua_State *L) {
+ global_State *g = G(L);
+ /*lua_checkmemory(L);*/
+ switch (g->gcstate) {
+ case GCSpause: {
+ markroot(L); /* start a new collection */
+ return 0;
+ }
+ case GCSpropagate: {
+ if (g->gray)
+ return propagatemark(g);
+ else { /* no more `gray' objects */
+ atomic(L); /* finish mark phase */
+ return 0;
+ }
+ }
+ case GCSsweepstring: {
+ lu_mem old = g->totalbytes;
+ sweepwholelist(L, &g->strt.hash[g->sweepstrgc++]);
+ if (g->sweepstrgc >= g->strt.size) /* nothing more to sweep? */
+ g->gcstate = GCSsweep; /* end sweep-string phase */
+ lua_assert(old >= g->totalbytes);
+ g->estimate -= old - g->totalbytes;
+ return GCSWEEPCOST;
+ }
+ case GCSsweep: {
+ lu_mem old = g->totalbytes;
+ g->sweepgc = sweeplist(L, g->sweepgc, GCSWEEPMAX);
+ if (*g->sweepgc == NULL) { /* nothing more to sweep? */
+ checkSizes(L);
+ g->gcstate = GCSfinalize; /* end sweep phase */
+ }
+ lua_assert(old >= g->totalbytes);
+ g->estimate -= old - g->totalbytes;
+ return GCSWEEPMAX*GCSWEEPCOST;
+ }
+ case GCSfinalize: {
+ if (g->tmudata) {
+ GCTM(L);
+ if (g->estimate > GCFINALIZECOST)
+ g->estimate -= GCFINALIZECOST;
+ return GCFINALIZECOST;
+ }
+ else {
+ g->gcstate = GCSpause; /* end collection */
+ g->gcdept = 0;
+ return 0;
+ }
+ }
+ default: lua_assert(0); return 0;
+ }
+}
+
+
+void luaC_step (lua_State *L) {
+ global_State *g = G(L);
+ l_mem lim = (GCSTEPSIZE/100) * g->gcstepmul;
+ if (lim == 0)
+ lim = (MAX_LUMEM-1)/2; /* no limit */
+ g->gcdept += g->totalbytes - g->GCthreshold;
+ do {
+ lim -= singlestep(L);
+ if (g->gcstate == GCSpause)
+ break;
+ } while (lim > 0);
+ if (g->gcstate != GCSpause) {
+ if (g->gcdept < GCSTEPSIZE)
+ g->GCthreshold = g->totalbytes + GCSTEPSIZE; /* - lim/g->gcstepmul;*/
+ else {
+ g->gcdept -= GCSTEPSIZE;
+ g->GCthreshold = g->totalbytes;
+ }
+ }
+ else {
+ lua_assert(g->totalbytes >= g->estimate);
+ setthreshold(g);
+ }
+}
+
+
+void luaC_fullgc (lua_State *L) {
+ global_State *g = G(L);
+ if (g->gcstate <= GCSpropagate) {
+ /* reset sweep marks to sweep all elements (returning them to white) */
+ g->sweepstrgc = 0;
+ g->sweepgc = &g->rootgc;
+ /* reset other collector lists */
+ g->gray = NULL;
+ g->grayagain = NULL;
+ g->weak = NULL;
+ g->gcstate = GCSsweepstring;
+ }
+ lua_assert(g->gcstate != GCSpause && g->gcstate != GCSpropagate);
+ /* finish any pending sweep phase */
+ while (g->gcstate != GCSfinalize) {
+ lua_assert(g->gcstate == GCSsweepstring || g->gcstate == GCSsweep);
+ singlestep(L);
+ }
+ markroot(L);
+ while (g->gcstate != GCSpause) {
+ singlestep(L);
+ }
+ setthreshold(g);
+}
+
+
+void luaC_barrierf (lua_State *L, GCObject *o, GCObject *v) {
+ global_State *g = G(L);
+ lua_assert(isblack(o) && iswhite(v) && !isdead(g, v) && !isdead(g, o));
+ lua_assert(g->gcstate != GCSfinalize && g->gcstate != GCSpause);
+ lua_assert(ttype(&o->gch) != LUA_TTABLE);
+ /* must keep invariant? */
+ if (g->gcstate == GCSpropagate)
+ reallymarkobject(g, v); /* restore invariant */
+ else /* don't mind */
+ makewhite(g, o); /* mark as white just to avoid other barriers */
+}
+
+
+void luaC_barrierback (lua_State *L, Table *t) {
+ global_State *g = G(L);
+ GCObject *o = obj2gco(t);
+ lua_assert(isblack(o) && !isdead(g, o));
+ lua_assert(g->gcstate != GCSfinalize && g->gcstate != GCSpause);
+ black2gray(o); /* make table gray (again) */
+ t->gclist = g->grayagain;
+ g->grayagain = o;
+}
+
+
+void luaC_link (lua_State *L, GCObject *o, lu_byte tt) {
+ global_State *g = G(L);
+ o->gch.next = g->rootgc;
+ g->rootgc = o;
+ o->gch.marked = luaC_white(g);
+ o->gch.tt = tt;
+}
+
+
+void luaC_linkupval (lua_State *L, UpVal *uv) {
+ global_State *g = G(L);
+ GCObject *o = obj2gco(uv);
+ o->gch.next = g->rootgc; /* link upvalue into `rootgc' list */
+ g->rootgc = o;
+ if (isgray(o)) {
+ if (g->gcstate == GCSpropagate) {
+ gray2black(o); /* closed upvalues need barrier */
+ luaC_barrier(L, uv, uv->v);
+ }
+ else { /* sweep phase: sweep it (turning it into white) */
+ makewhite(g, o);
+ lua_assert(g->gcstate != GCSfinalize && g->gcstate != GCSpause);
+ }
+ }
+}
+