diff options
Diffstat (limited to 'lua/lgc.c')
| -rw-r--r-- | lua/lgc.c | 456 |
1 files changed, 279 insertions, 177 deletions
@@ -1,5 +1,5 @@ /* -** $Id: lgc.c,v 2.116 2011/12/02 13:18:41 roberto Exp $ +** $Id: lgc.c,v 2.133 2012/05/31 21:28:59 roberto Exp $ ** Garbage Collector ** See Copyright Notice in lua.h */ @@ -24,34 +24,40 @@ -/* how much to allocate before next GC step */ -#define GCSTEPSIZE 1024 +/* +** cost of sweeping one element (the size of a small object divided +** by some adjust for the sweep speed) +*/ +#define GCSWEEPCOST ((sizeof(TString) + 4) / 4) /* maximum number of elements to sweep in each single step */ -#define GCSWEEPMAX 40 - -/* cost of sweeping one element */ -#define GCSWEEPCOST 1 +#define GCSWEEPMAX (cast_int((GCSTEPSIZE / GCSWEEPCOST) / 4)) /* maximum number of finalizers to call in each GC step */ #define GCFINALIZENUM 4 -/* cost of marking the root set */ -#define GCROOTCOST 10 -/* cost of atomic step */ -#define GCATOMICCOST 1000 +/* +** macro to adjust 'stepmul': 'stepmul' is actually used like +** 'stepmul / STEPMULADJ' (value chosen by tests) +*/ +#define STEPMULADJ 200 + +/* +** macro to adjust 'pause': 'pause' is actually used like +** 'pause / PAUSEADJ' (value chosen by tests) +*/ +#define PAUSEADJ 200 + -/* basic cost to traverse one object (to be added to the links the - object may have) */ -#define TRAVCOST 5 /* ** standard negative debt for GC; a reasonable "time" to wait before ** starting a new cycle */ -#define stddebt(g) (-cast(l_mem, gettotalbytes(g)/100) * g->gcpause) +#define stddebtest(g,e) (-cast(l_mem, (e)/PAUSEADJ) * g->gcpause) +#define stddebt(g) stddebtest(g, gettotalbytes(g)) /* @@ -65,8 +71,6 @@ #define white2gray(x) resetbits(gch(x)->marked, WHITEBITS) #define black2gray(x) resetbit(gch(x)->marked, BLACKBIT) -#define stringmark(s) ((void)((s) && resetbits((s)->tsv.marked, WHITEBITS))) - #define isfinalized(x) testbit(gch(x)->marked, FINALIZEDBIT) @@ -123,10 +127,10 @@ static void removeentry (Node *n) { ** other objects: if really collected, cannot keep them; for objects ** being finalized, keep them in keys, but not in values */ -static int iscleared (const TValue *o) { +static int iscleared (global_State *g, const TValue *o) { if (!iscollectable(o)) return 0; else if (ttisstring(o)) { - stringmark(rawtsvalue(o)); /* strings are `values', so are never weak */ + markobject(g, rawtsvalue(o)); /* strings are `values', so are never weak */ return 0; } else return iswhite(gcvalue(o)); @@ -217,7 +221,8 @@ void luaC_checkupvalcolor (global_State *g, UpVal *uv) { GCObject *luaC_newobj (lua_State *L, int tt, size_t sz, GCObject **list, int offset) { global_State *g = G(L); - GCObject *o = obj2gco(cast(char *, luaM_newobject(L, tt, sz)) + offset); + char *raw = cast(char *, luaM_newobject(L, novariant(tt), sz)); + GCObject *o = obj2gco(raw + offset); if (list == NULL) list = &g->allgc; /* standard list for collectable objects */ gch(o)->marked = luaC_white(g); @@ -239,54 +244,63 @@ GCObject *luaC_newobj (lua_State *L, int tt, size_t sz, GCObject **list, /* -** mark an object. Userdata and closed upvalues are visited and turned -** black here. Strings remain gray (it is the same as making them -** black). Other objects are marked gray and added to appropriate list -** to be visited (and turned black) later. (Open upvalues are already -** linked in 'headuv' list.) +** mark an object. Userdata, strings, and closed upvalues are visited +** and turned black here. Other objects are marked gray and added +** to appropriate list to be visited (and turned black) later. (Open +** upvalues are already linked in 'headuv' list.) */ static void reallymarkobject (global_State *g, GCObject *o) { - lua_assert(iswhite(o) && !isdead(g, o)); + lu_mem size; white2gray(o); switch (gch(o)->tt) { - case LUA_TSTRING: { - return; /* for strings, gray is as good as black */ + case LUA_TSHRSTR: + case LUA_TLNGSTR: { + size = sizestring(gco2ts(o)); + break; /* nothing else to mark; make it black */ } case LUA_TUSERDATA: { Table *mt = gco2u(o)->metatable; markobject(g, mt); markobject(g, gco2u(o)->env); - gray2black(o); /* all pointers marked */ - return; + size = sizeudata(gco2u(o)); + break; } case LUA_TUPVAL: { UpVal *uv = gco2uv(o); markvalue(g, uv->v); - if (uv->v == &uv->u.value) /* closed? (open upvalues remain gray) */ - gray2black(o); /* make it black */ + if (uv->v != &uv->u.value) /* open? */ + return; /* open upvalues remain gray */ + size = sizeof(UpVal); + break; + } + case LUA_TLCL: { + gco2lcl(o)->gclist = g->gray; + g->gray = o; return; } - case LUA_TFUNCTION: { - gco2cl(o)->c.gclist = g->gray; + case LUA_TCCL: { + gco2ccl(o)->gclist = g->gray; g->gray = o; - break; + return; } case LUA_TTABLE: { linktable(gco2t(o), &g->gray); - break; + return; } case LUA_TTHREAD: { gco2th(o)->gclist = g->gray; g->gray = o; - break; + return; } case LUA_TPROTO: { gco2p(o)->gclist = g->gray; g->gray = o; - break; + return; } - default: lua_assert(0); + default: lua_assert(0); return; } + gray2black(o); + g->GCmemtrav += size; } @@ -359,7 +373,7 @@ static void traverseweakvalue (global_State *g, Table *h) { else { lua_assert(!ttisnil(gkey(n))); markvalue(g, gkey(n)); /* mark key */ - if (!hasclears && iscleared(gval(n))) /* is there a white value? */ + if (!hasclears && iscleared(g, gval(n))) /* is there a white value? */ hasclears = 1; /* table will have to be cleared */ } } @@ -388,7 +402,7 @@ 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))) { /* key is not marked (yet)? */ + else if (iscleared(g, gkey(n))) { /* key is not marked (yet)? */ hasclears = 1; /* table must be cleared */ if (valiswhite(gval(n))) /* value not marked yet? */ prop = 1; /* must propagate again */ @@ -426,30 +440,26 @@ static void traversestrongtable (global_State *g, Table *h) { } -static int traversetable (global_State *g, Table *h) { +static lu_mem traversetable (global_State *g, Table *h) { + const char *weakkey, *weakvalue; const TValue *mode = gfasttm(g, h->metatable, TM_MODE); markobject(g, h->metatable); - if (mode && ttisstring(mode)) { /* is there a weak mode? */ - int weakkey = (strchr(svalue(mode), 'k') != NULL); - int weakvalue = (strchr(svalue(mode), 'v') != NULL); - if (weakkey || weakvalue) { /* is really weak? */ - black2gray(obj2gco(h)); /* keep table gray */ - if (!weakkey) { /* strong keys? */ - traverseweakvalue(g, h); - return TRAVCOST + sizenode(h); - } - else if (!weakvalue) { /* strong values? */ - traverseephemeron(g, h); - return TRAVCOST + h->sizearray + sizenode(h); - } - else { - linktable(h, &g->allweak); /* nothing to traverse now */ - return TRAVCOST; - } - } /* else go through */ + if (mode && ttisstring(mode) && /* is there a weak mode? */ + ((weakkey = strchr(svalue(mode), 'k')), + (weakvalue = strchr(svalue(mode), 'v')), + (weakkey || weakvalue))) { /* is really weak? */ + black2gray(obj2gco(h)); /* keep table gray */ + if (!weakkey) /* strong keys? */ + traverseweakvalue(g, h); + else if (!weakvalue) /* strong values? */ + traverseephemeron(g, h); + else /* all weak */ + linktable(h, &g->allweak); /* nothing to traverse now */ } - traversestrongtable(g, h); - return TRAVCOST + h->sizearray + (2 * sizenode(h)); + else /* not weak */ + traversestrongtable(g, h); + return sizeof(Table) + sizeof(TValue) * h->sizearray + + sizeof(Node) * sizenode(h); } @@ -457,86 +467,101 @@ static int traverseproto (global_State *g, Proto *f) { int i; if (f->cache && iswhite(obj2gco(f->cache))) f->cache = NULL; /* allow cache to be collected */ - stringmark(f->source); + markobject(g, 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 */ - stringmark(f->upvalues[i].name); + markobject(g, f->upvalues[i].name); for (i = 0; i < f->sizep; i++) /* mark nested protos */ markobject(g, f->p[i]); for (i = 0; i < f->sizelocvars; i++) /* mark local-variable names */ - stringmark(f->locvars[i].varname); - return TRAVCOST + f->sizek + f->sizeupvalues + f->sizep + f->sizelocvars; + markobject(g, f->locvars[i].varname); + return sizeof(Proto) + sizeof(Instruction) * f->sizecode + + sizeof(Proto *) * f->sizep + + sizeof(TValue) * f->sizek + + sizeof(int) * f->sizelineinfo + + sizeof(LocVar) * f->sizelocvars + + sizeof(Upvaldesc) * f->sizeupvalues; } -static int traverseclosure (global_State *g, Closure *cl) { - 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->sizeupvalues); - markobject(g, cl->l.p); /* mark its prototype */ - for (i=0; i<cl->l.nupvalues; i++) /* mark its upvalues */ - markobject(g, cl->l.upvals[i]); - } - return TRAVCOST + cl->c.nupvalues; +static lu_mem traverseCclosure (global_State *g, CClosure *cl) { + int i; + for (i = 0; i < cl->nupvalues; i++) /* mark its upvalues */ + markvalue(g, &cl->upvalue[i]); + return sizeCclosure(cl->nupvalues); +} + +static lu_mem traverseLclosure (global_State *g, LClosure *cl) { + int i; + markobject(g, cl->p); /* mark its prototype */ + for (i = 0; i < cl->nupvalues; i++) /* mark its upvalues */ + markobject(g, cl->upvals[i]); + return sizeLclosure(cl->nupvalues); } -static int traversestack (global_State *g, lua_State *L) { - StkId o = L->stack; +static lu_mem traversestack (global_State *g, lua_State *th) { + StkId o = th->stack; if (o == NULL) return 1; /* stack not completely built yet */ - for (; o < L->top; o++) + for (; o < th->top; o++) markvalue(g, o); if (g->gcstate == GCSatomic) { /* final traversal? */ - StkId lim = L->stack + L->stacksize; /* real end of stack */ + StkId lim = th->stack + th->stacksize; /* real end of stack */ for (; o < lim; o++) /* clear not-marked stack slice */ setnilvalue(o); } - return TRAVCOST + cast_int(o - L->stack); + return sizeof(lua_State) + sizeof(TValue) * th->stacksize; } /* ** traverse one gray object, turning it to black (except for threads, ** which are always gray). -** Returns number of values traversed. */ -static int propagatemark (global_State *g) { +static void propagatemark (global_State *g) { + lu_mem size; GCObject *o = g->gray; lua_assert(isgray(o)); gray2black(o); switch (gch(o)->tt) { case LUA_TTABLE: { Table *h = gco2t(o); - g->gray = h->gclist; - return traversetable(g, h); + g->gray = h->gclist; /* remove from 'gray' list */ + size = traversetable(g, h); + break; + } + case LUA_TLCL: { + LClosure *cl = gco2lcl(o); + g->gray = cl->gclist; /* remove from 'gray' list */ + size = traverseLclosure(g, cl); + break; } - case LUA_TFUNCTION: { - Closure *cl = gco2cl(o); - g->gray = cl->c.gclist; - return traverseclosure(g, cl); + case LUA_TCCL: { + CClosure *cl = gco2ccl(o); + g->gray = cl->gclist; /* remove from 'gray' list */ + size = traverseCclosure(g, cl); + break; } case LUA_TTHREAD: { lua_State *th = gco2th(o); - g->gray = th->gclist; + g->gray = th->gclist; /* remove from 'gray' list */ th->gclist = g->grayagain; - g->grayagain = o; + g->grayagain = o; /* insert into 'grayagain' list */ black2gray(o); - return traversestack(g, th); + size = traversestack(g, th); + break; } case LUA_TPROTO: { Proto *p = gco2p(o); - g->gray = p->gclist; - return traverseproto(g, p); + g->gray = p->gclist; /* remove from 'gray' list */ + size = traverseproto(g, p); + break; } - default: lua_assert(0); return 0; + default: lua_assert(0); return; } + g->GCmemtrav += size; } @@ -599,12 +624,12 @@ static void convergeephemerons (global_State *g) { ** clear entries with unmarked keys from all weaktables in list 'l' up ** to element 'f' */ -static void clearkeys (GCObject *l, GCObject *f) { +static void clearkeys (global_State *g, GCObject *l, GCObject *f) { for (; l != f; l = gco2t(l)->gclist) { Table *h = gco2t(l); Node *n, *limit = gnodelast(h); for (n = gnode(h, 0); n < limit; n++) { - if (!ttisnil(gval(n)) && (iscleared(gkey(n)))) { + if (!ttisnil(gval(n)) && (iscleared(g, gkey(n)))) { setnilvalue(gval(n)); /* remove value ... */ removeentry(n); /* and remove entry from table */ } @@ -617,18 +642,18 @@ static void clearkeys (GCObject *l, GCObject *f) { ** clear entries with unmarked values from all weaktables in list 'l' up ** to element 'f' */ -static void clearvalues (GCObject *l, GCObject *f) { +static void clearvalues (global_State *g, GCObject *l, GCObject *f) { for (; l != f; l = gco2t(l)->gclist) { Table *h = gco2t(l); Node *n, *limit = gnodelast(h); int i; for (i = 0; i < h->sizearray; i++) { TValue *o = &h->array[i]; - if (iscleared(o)) /* value was collected? */ + if (iscleared(g, o)) /* value was collected? */ setnilvalue(o); /* remove value */ } for (n = gnode(h, 0); n < limit; n++) { - if (!ttisnil(gval(n)) && iscleared(gval(n))) { + if (!ttisnil(gval(n)) && iscleared(g, gval(n))) { setnilvalue(gval(n)); /* remove value ... */ removeentry(n); /* and remove entry from table */ } @@ -640,13 +665,22 @@ static void clearvalues (GCObject *l, GCObject *f) { static void freeobj (lua_State *L, GCObject *o) { switch (gch(o)->tt) { case LUA_TPROTO: luaF_freeproto(L, gco2p(o)); break; - case LUA_TFUNCTION: luaF_freeclosure(L, gco2cl(o)); break; + case LUA_TLCL: { + luaM_freemem(L, o, sizeLclosure(gco2lcl(o)->nupvalues)); + break; + } + case LUA_TCCL: { + luaM_freemem(L, o, sizeCclosure(gco2ccl(o)->nupvalues)); + break; + } case LUA_TUPVAL: luaF_freeupval(L, gco2uv(o)); break; case LUA_TTABLE: luaH_free(L, gco2t(o)); break; case LUA_TTHREAD: luaE_freethread(L, gco2th(o)); break; case LUA_TUSERDATA: luaM_freemem(L, o, sizeudata(gco2u(o))); break; - case LUA_TSTRING: { + case LUA_TSHRSTR: G(L)->strt.nuse--; + /* go through */ + case LUA_TLNGSTR: { luaM_freemem(L, o, sizestring(gco2ts(o))); break; } @@ -689,7 +723,6 @@ static GCObject **sweeplist (lua_State *L, GCObject **p, lu_mem count) { int ow = otherwhite(g); int toclear, toset; /* bits to clear and to set in all live objects */ int tostop; /* stop sweep when this is true */ - l_mem debt = g->GCdebt; /* current debt */ if (isgenerational(g)) { /* generational mode? */ toclear = ~0; /* clear nothing */ toset = bitmask(OLDBIT); /* set the old bit of all surviving objects */ @@ -708,19 +741,30 @@ static GCObject **sweeplist (lua_State *L, GCObject **p, lu_mem count) { freeobj(L, curr); /* erase 'curr' */ } else { + if (testbits(marked, tostop)) + return NULL; /* stop sweeping this list */ if (gch(curr)->tt == LUA_TTHREAD) sweepthread(L, gco2th(curr)); /* sweep thread's upvalues */ - if (testbits(marked, tostop)) { - static GCObject *nullp = NULL; - p = &nullp; /* stop sweeping this list */ - break; - } /* update marks */ gch(curr)->marked = cast_byte((marked & toclear) | toset); p = &gch(curr)->next; /* go to next element */ } } - luaE_setdebt(g, debt); /* sweeping should not change debt */ + return (*p == NULL) ? NULL : p; +} + + +/* +** sweep a list until a live object (or end of list) +*/ +static GCObject **sweeptolive (lua_State *L, GCObject **p, int *n) { + GCObject ** old = p; + int i = 0; + do { + i++; + p = sweeplist(L, p, 1); + } while (p == old); + if (n) *n += i; return p; } @@ -783,12 +827,14 @@ static void GCTM (lua_State *L, int propagateerrors) { L->allowhook = oldah; /* restore hooks */ g->gcrunning = running; /* restore state */ if (status != LUA_OK && propagateerrors) { /* error while running __gc? */ - if (status == LUA_ERRRUN) { /* is there an error msg.? */ - luaO_pushfstring(L, "error in __gc metamethod (%s)", - lua_tostring(L, -1)); + if (status == LUA_ERRRUN) { /* is there an error object? */ + const char *msg = (ttisstring(L->top - 1)) + ? svalue(L->top - 1) + : "no message"; + luaO_pushfstring(L, "error in __gc metamethod (%s)", msg); status = LUA_ERRGCMM; /* error in __gc metamethod */ } - luaD_throw(L, status); /* re-send error */ + luaD_throw(L, status); /* re-throw error */ } } } @@ -834,12 +880,21 @@ void luaC_checkfinalizer (lua_State *L, GCObject *o, Table *mt) { return; /* nothing to be done */ else { /* move 'o' to 'finobj' list */ GCObject **p; - for (p = &g->allgc; *p != o; p = &gch(*p)->next) ; - *p = gch(o)->next; /* remove 'o' from root list */ - gch(o)->next = g->finobj; /* link it in list 'finobj' */ + GCheader *ho = gch(o); + if (g->sweepgc == &ho->next) { /* avoid removing current sweep object */ + lua_assert(issweepphase(g)); + g->sweepgc = sweeptolive(L, g->sweepgc, NULL); + } + /* search for pointer pointing to 'o' */ + for (p = &g->allgc; *p != o; p = &gch(*p)->next) { /* empty */ } + *p = ho->next; /* remove 'o' from root list */ + ho->next = g->finobj; /* link it in list 'finobj' */ g->finobj = o; - l_setbit(gch(o)->marked, SEPARATED); /* mark it as such */ - resetoldbit(o); /* see MOVE OLD rule */ + l_setbit(ho->marked, SEPARATED); /* mark it as such */ + if (!keepinvariant(g)) /* not keeping invariant? */ + makewhite(g, o); /* "sweep" object */ + else + resetoldbit(o); /* see MOVE OLD rule */ } } @@ -856,6 +911,28 @@ void luaC_checkfinalizer (lua_State *L, GCObject *o, Table *mt) { #define sweepphases \ (bitmask(GCSsweepstring) | bitmask(GCSsweepudata) | bitmask(GCSsweep)) + +/* +** enter first sweep phase (strings) and prepare pointers for other +** sweep phases. The calls to 'sweeptolive' make pointers point to an +** object inside the list (instead of to the header), so that the real +** sweep do not need to skip objects created between "now" and the start +** of the real sweep. +** Returns how many objects it sweeped. +*/ +static int entersweep (lua_State *L) { + global_State *g = G(L); + int n = 0; + g->gcstate = GCSsweepstring; + lua_assert(g->sweepgc == NULL && g->sweepfin == NULL); + /* prepare to sweep strings, finalizable objects, and regular objects */ + g->sweepstrgc = 0; + g->sweepfin = sweeptolive(L, &g->finobj, &n); + g->sweepgc = sweeptolive(L, &g->allgc, &n); + return n; +} + + /* ** change GC mode */ @@ -865,15 +942,14 @@ void luaC_changemode (lua_State *L, int mode) { if (mode == KGC_GEN) { /* change to generational mode */ /* make sure gray lists are consistent */ luaC_runtilstate(L, bitmask(GCSpropagate)); - g->lastmajormem = gettotalbytes(g); + g->GCestimate = gettotalbytes(g); g->gckind = KGC_GEN; } else { /* change to incremental mode */ /* sweep all objects to turn them back to white (as white has not changed, nothing extra will be collected) */ - g->sweepstrgc = 0; - g->gcstate = GCSsweepstring; g->gckind = KGC_NORMAL; + entersweep(L); luaC_runtilstate(L, ~sweepphases); } } @@ -907,8 +983,9 @@ void luaC_freeallobjects (lua_State *L) { } -static void atomic (lua_State *L) { +static l_mem atomic (lua_State *L) { global_State *g = G(L); + l_mem work = -g->GCmemtrav; /* start counting work */ GCObject *origweak, *origall; lua_assert(!iswhite(obj2gco(g->mainthread))); markobject(g, L); /* mark running thread */ @@ -917,77 +994,87 @@ static void atomic (lua_State *L) { markmt(g); /* mark basic metatables */ /* remark occasional upvalues of (maybe) dead threads */ remarkupvals(g); + propagateall(g); /* propagate changes */ + work += g->GCmemtrav; /* stop counting (do not (re)count grays) */ /* traverse objects caught by write barrier and by 'remarkupvals' */ retraversegrays(g); + work -= g->GCmemtrav; /* restart counting */ convergeephemerons(g); /* at this point, all strongly accessible objects are marked. */ /* clear values from weak tables, before checking finalizers */ - clearvalues(g->weak, NULL); - clearvalues(g->allweak, NULL); + clearvalues(g, g->weak, NULL); + clearvalues(g, g->allweak, NULL); origweak = g->weak; origall = g->allweak; + work += g->GCmemtrav; /* stop counting (objects being finalized) */ separatetobefnz(L, 0); /* separate objects to be finalized */ - markbeingfnz(g); /* mark userdata that will be finalized */ + markbeingfnz(g); /* mark objects that will be finalized */ propagateall(g); /* remark, to propagate `preserveness' */ + work -= g->GCmemtrav; /* restart counting */ convergeephemerons(g); /* at this point, all resurrected objects are marked. */ /* remove dead objects from weak tables */ - clearkeys(g->ephemeron, NULL); /* clear keys from all ephemeron tables */ - clearkeys(g->allweak, NULL); /* clear keys from all allweak tables */ + clearkeys(g, g->ephemeron, NULL); /* clear keys from all ephemeron tables */ + clearkeys(g, g->allweak, NULL); /* clear keys from all allweak tables */ /* clear values from resurrected weak tables */ - clearvalues(g->weak, origweak); - clearvalues(g->allweak, origall); - g->sweepstrgc = 0; /* prepare to sweep strings */ - g->gcstate = GCSsweepstring; + clearvalues(g, g->weak, origweak); + clearvalues(g, g->allweak, origall); g->currentwhite = cast_byte(otherwhite(g)); /* flip current white */ - /*lua_checkmemory(L);*/ + work += g->GCmemtrav; /* complete counting */ + return work; /* estimate of memory marked by 'atomic' */ } -static l_mem singlestep (lua_State *L) { +static lu_mem singlestep (lua_State *L) { global_State *g = G(L); switch (g->gcstate) { case GCSpause: { + g->GCmemtrav = 0; /* start to count memory traversed */ if (!isgenerational(g)) markroot(g); /* start a new collection */ - /* in any case, root must be marked */ + /* in any case, root must be marked at this point */ lua_assert(!iswhite(obj2gco(g->mainthread)) && !iswhite(gcvalue(&g->l_registry))); g->gcstate = GCSpropagate; - return GCROOTCOST; + return g->GCmemtrav; } case GCSpropagate: { - if (g->gray) - return propagatemark(g); + if (g->gray) { + lu_mem oldtrav = g->GCmemtrav; + propagatemark(g); + return g->GCmemtrav - oldtrav; /* memory traversed in this step */ + } else { /* no more `gray' objects */ + lu_mem work; + int sw; g->gcstate = GCSatomic; /* finish mark phase */ - atomic(L); - return GCATOMICCOST; + g->GCestimate = g->GCmemtrav; /* save what was counted */; + work = atomic(L); /* add what was traversed by 'atomic' */ + g->GCestimate += work; /* estimate of total memory traversed */ + sw = entersweep(L); + return work + sw * GCSWEEPCOST; } } case GCSsweepstring: { - if (g->sweepstrgc < g->strt.size) { - sweepwholelist(L, &g->strt.hash[g->sweepstrgc++]); - return GCSWEEPCOST; - } - else { /* no more strings to sweep */ - g->sweepgc = &g->finobj; /* prepare to sweep finalizable objects */ + int i; + for (i = 0; i < GCSWEEPMAX && g->sweepstrgc + i < g->strt.size; i++) + sweepwholelist(L, &g->strt.hash[g->sweepstrgc + i]); + g->sweepstrgc += i; + if (g->sweepstrgc >= g->strt.size) /* no more strings to sweep? */ g->gcstate = GCSsweepudata; - return 0; - } + return i * GCSWEEPCOST; } case GCSsweepudata: { - if (*g->sweepgc) { - g->sweepgc = sweeplist(L, g->sweepgc, GCSWEEPMAX); + if (g->sweepfin) { + g->sweepfin = sweeplist(L, g->sweepfin, GCSWEEPMAX); return GCSWEEPMAX*GCSWEEPCOST; } else { - g->sweepgc = &g->allgc; /* go to next phase */ g->gcstate = GCSsweep; - return GCSWEEPCOST; + return 0; } } case GCSsweep: { - if (*g->sweepgc) { + if (g->sweepgc) { g->sweepgc = sweeplist(L, g->sweepgc, GCSWEEPMAX); return GCSWEEPMAX*GCSWEEPCOST; } @@ -1018,43 +1105,52 @@ void luaC_runtilstate (lua_State *L, int statesmask) { static void generationalcollection (lua_State *L) { global_State *g = G(L); - if (g->lastmajormem == 0) { /* signal for another major collection? */ + if (g->GCestimate == 0) { /* signal for another major collection? */ luaC_fullgc(L, 0); /* perform a full regular collection */ - g->lastmajormem = gettotalbytes(g); /* update control */ + g->GCestimate = gettotalbytes(g); /* update control */ } else { + lu_mem estimate = g->GCestimate; luaC_runtilstate(L, ~bitmask(GCSpause)); /* run complete cycle */ luaC_runtilstate(L, bitmask(GCSpause)); - if (gettotalbytes(g) > g->lastmajormem/100 * g->gcmajorinc) - g->lastmajormem = 0; /* signal for a major collection */ + if (gettotalbytes(g) > (estimate / 100) * g->gcmajorinc) + g->GCestimate = 0; /* signal for a major collection */ } luaE_setdebt(g, stddebt(g)); } -static void step (lua_State *L) { +static void incstep (lua_State *L) { global_State *g = G(L); - l_mem lim = g->gcstepmul; /* how much to work */ + l_mem debt = g->GCdebt; + int stepmul = g->gcstepmul; + if (stepmul < 40) stepmul = 40; /* avoid ridiculous low values */ + /* convert debt from Kb to 'work units' (avoid zero debt and overflows) */ + debt = (debt / STEPMULADJ) + 1; + debt = (debt < MAX_LMEM / stepmul) ? debt * stepmul : MAX_LMEM; do { /* always perform at least one single step */ - lim -= singlestep(L); - } while (lim > 0 && g->gcstate != GCSpause); - if (g->gcstate != GCSpause) - luaE_setdebt(g, g->GCdebt - GCSTEPSIZE); + lu_mem work = singlestep(L); /* do some work */ + debt -= work; + } while (debt > -GCSTEPSIZE && g->gcstate != GCSpause); + if (g->gcstate == GCSpause) + debt = stddebtest(g, g->GCestimate); /* pause until next cycle */ else - luaE_setdebt(g, stddebt(g)); + debt = (debt / stepmul) * STEPMULADJ; /* convert 'work units' to Kb */ + luaE_setdebt(g, debt); } /* -** performs a basic GC step even if the collector is stopped +** performs a basic GC step */ void luaC_forcestep (lua_State *L) { global_State *g = G(L); int i; if (isgenerational(g)) generationalcollection(L); - else step(L); - for (i = 0; i < GCFINALIZENUM && g->tobefnz; i++) - GCTM(L, 1); /* Call a few pending finalizers */ + else incstep(L); + /* run a few finalizers (or all of them at the end of a collect cycle) */ + for (i = 0; g->tobefnz && (i < GCFINALIZENUM || g->gcstate == GCSpause); i++) + GCTM(L, 1); /* call one finalizer */ } @@ -1062,10 +1158,13 @@ void luaC_forcestep (lua_State *L) { ** performs a basic GC step only if collector is running */ void luaC_step (lua_State *L) { - if (G(L)->gcrunning) luaC_forcestep(L); + global_State *g = G(L); + if (g->gcrunning) luaC_forcestep(L); + else luaE_setdebt(g, -GCSTEPSIZE); /* avoid being called too often */ } + /* ** performs a full GC cycle; if "isemergency", does not call ** finalizers (which could change stack positions) @@ -1073,16 +1172,19 @@ void luaC_step (lua_State *L) { void luaC_fullgc (lua_State *L, int isemergency) { global_State *g = G(L); int origkind = g->gckind; + int someblack = keepinvariant(g); lua_assert(origkind != KGC_EMERGENCY); - if (!isemergency) /* do not run finalizers during emergency GC */ + if (isemergency) /* do not run finalizers during emergency GC */ + g->gckind = KGC_EMERGENCY; + else { + g->gckind = KGC_NORMAL; callallpendingfinalizers(L, 1); - if (keepinvariant(g)) { /* marking phase? */ + } + if (someblack) { /* may there be some black objects? */ /* must sweep all objects to turn them back to white (as white has not changed, nothing will be collected) */ - g->sweepstrgc = 0; - g->gcstate = GCSsweepstring; + entersweep(L); } - g->gckind = isemergency ? KGC_EMERGENCY : KGC_NORMAL; /* finish any pending sweep phase to start a new cycle */ luaC_runtilstate(L, bitmask(GCSpause)); /* run entire collector */ |