diff options
Diffstat (limited to 'lua/lgc.c')
| -rw-r--r-- | lua/lgc.c | 1236 |
1 files changed, 814 insertions, 422 deletions
@@ -1,5 +1,5 @@ /* -** $Id: lgc.c,v 2.38.1.1 2007/12/27 13:02:25 roberto Exp $ +** $Id: lgc.c,v 2.116 2011/12/02 13:18:41 roberto Exp $ ** Garbage Collector ** See Copyright Notice in lua.h */ @@ -23,68 +23,247 @@ #include "ltm.h" -#define GCSTEPSIZE 1024u + +/* how much to allocate before next GC step */ +#define GCSTEPSIZE 1024 + +/* maximum number of elements to sweep in each single step */ #define GCSWEEPMAX 40 -#define GCSWEEPCOST 10 -#define GCFINALIZECOST 100 +/* cost of sweeping one element */ +#define GCSWEEPCOST 1 + +/* 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 + +/* 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 maskmarks cast_byte(~(bitmask(BLACKBIT)|WHITEBITS)) +/* +** 'makewhite' erases all color bits plus the old bit and then +** sets only the current white bit +*/ +#define maskcolors (~(bit2mask(BLACKBIT, OLDBIT) | WHITEBITS)) #define makewhite(g,x) \ - ((x)->gch.marked = cast_byte(((x)->gch.marked & maskmarks) | luaC_white(g))) + (gch(x)->marked = cast_byte((gch(x)->marked & maskcolors) | luaC_white(g))) -#define white2gray(x) reset2bits((x)->gch.marked, WHITE0BIT, WHITE1BIT) -#define black2gray(x) resetbit((x)->gch.marked, BLACKBIT) +#define white2gray(x) resetbits(gch(x)->marked, WHITEBITS) +#define black2gray(x) resetbit(gch(x)->marked, BLACKBIT) -#define stringmark(s) reset2bits((s)->tsv.marked, WHITE0BIT, WHITE1BIT) +#define stringmark(s) ((void)((s) && resetbits((s)->tsv.marked, WHITEBITS))) -#define isfinalized(u) testbit((u)->marked, FINALIZEDBIT) -#define markfinalized(u) l_setbit((u)->marked, FINALIZEDBIT) +#define isfinalized(x) testbit(gch(x)->marked, FINALIZEDBIT) +#define checkdeadkey(n) lua_assert(!ttisdeadkey(gkey(n)) || ttisnil(gval(n))) -#define KEYWEAK bitmask(KEYWEAKBIT) -#define VALUEWEAK bitmask(VALUEWEAKBIT) +#define checkconsistency(obj) \ + lua_longassert(!iscollectable(obj) || righttt(obj)) #define markvalue(g,o) { checkconsistency(o); \ - if (iscollectable(o) && iswhite(gcvalue(o))) reallymarkobject(g,gcvalue(o)); } + if (valiswhite(o)) reallymarkobject(g,gcvalue(o)); } -#define markobject(g,t) { if (iswhite(obj2gco(t))) \ +#define markobject(g,t) { if ((t) && iswhite(obj2gco(t))) \ reallymarkobject(g, obj2gco(t)); } +static void reallymarkobject (global_State *g, GCObject *o); + + +/* +** {====================================================== +** Generic functions +** ======================================================= +*/ + + +/* +** one after last element in a hash array +*/ +#define gnodelast(h) gnode(h, cast(size_t, sizenode(h))) + -#define setthreshold(g) (g->GCthreshold = (g->estimate/100) * g->gcpause) +/* +** link table 'h' into list pointed by 'p' +*/ +#define linktable(h,p) ((h)->gclist = *(p), *(p) = obj2gco(h)) +/* +** if key is not marked, mark its entry as dead (therefore removing it +** from the table) +*/ static void removeentry (Node *n) { lua_assert(ttisnil(gval(n))); - if (iscollectable(gkey(n))) - setttype(gkey(n), LUA_TDEADKEY); /* dead key; remove it */ + if (valiswhite(gkey(n))) + setdeadvalue(gkey(n)); /* unused and unmarked key; remove it */ +} + + +/* +** 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 objects +** being finalized, keep them in keys, but not in values +*/ +static int iscleared (const TValue *o) { + if (!iscollectable(o)) return 0; + else if (ttisstring(o)) { + stringmark(rawtsvalue(o)); /* strings are `values', so are never weak */ + return 0; + } + else return iswhite(gcvalue(o)); +} + + +/* +** barrier that moves collector forward, that is, mark the white object +** being pointed by a black object. +*/ +void luaC_barrier_ (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(isgenerational(g) || g->gcstate != GCSpause); + lua_assert(gch(o)->tt != LUA_TTABLE); + if (keepinvariant(g)) /* must keep invariant? */ + reallymarkobject(g, v); /* restore invariant */ + else { /* sweep phase */ + lua_assert(issweepphase(g)); + makewhite(g, o); /* mark main obj. as white to avoid other barriers */ + } +} + + +/* +** barrier that moves collector backward, that is, mark the black object +** pointing to a white object as gray again. (Current implementation +** only works for tables; access to 'gclist' is not uniform across +** different types.) +*/ +void luaC_barrierback_ (lua_State *L, GCObject *o) { + global_State *g = G(L); + lua_assert(isblack(o) && !isdead(g, o) && gch(o)->tt == LUA_TTABLE); + black2gray(o); /* make object gray (again) */ + gco2t(o)->gclist = g->grayagain; + g->grayagain = o; +} + + +/* +** barrier for prototypes. When creating first closure (cache is +** NULL), use a forward barrier; this may be the only closure of the +** prototype (if it is a "regular" function, with a single instance) +** and the prototype may be big, so it is better to avoid traversing +** it again. Otherwise, use a backward barrier, to avoid marking all +** possible instances. +*/ +LUAI_FUNC void luaC_barrierproto_ (lua_State *L, Proto *p, Closure *c) { + global_State *g = G(L); + lua_assert(isblack(obj2gco(p))); + if (p->cache == NULL) { /* first time? */ + luaC_objbarrier(L, p, c); + } + else { /* use a backward barrier */ + black2gray(obj2gco(p)); /* make prototype gray (again) */ + p->gclist = g->grayagain; + g->grayagain = obj2gco(p); + } } +/* +** check color (and invariants) for an upvalue that was closed, +** i.e., moved into the 'allgc' list +*/ +void luaC_checkupvalcolor (global_State *g, UpVal *uv) { + GCObject *o = obj2gco(uv); + lua_assert(!isblack(o)); /* open upvalues are never black */ + if (isgray(o)) { + if (keepinvariant(g)) { + resetoldbit(o); /* see MOVE OLD rule */ + gray2black(o); /* it is being visited now */ + markvalue(g, uv->v); + } + else { + lua_assert(issweepphase(g)); + makewhite(g, o); + } + } +} + + +/* +** create a new collectable object (with given type and size) and link +** it to '*list'. 'offset' tells how many bytes to allocate before the +** object itself (used only by states). +*/ +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); + if (list == NULL) + list = &g->allgc; /* standard list for collectable objects */ + gch(o)->marked = luaC_white(g); + gch(o)->tt = tt; + gch(o)->next = *list; + *list = o; + return o; +} + +/* }====================================================== */ + + + +/* +** {====================================================== +** Mark functions +** ======================================================= +*/ + + +/* +** 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.) +*/ static void reallymarkobject (global_State *g, GCObject *o) { lua_assert(iswhite(o) && !isdead(g, o)); white2gray(o); - switch (o->gch.tt) { + switch (gch(o)->tt) { case LUA_TSTRING: { - return; + return; /* for strings, gray is as good as black */ } case LUA_TUSERDATA: { Table *mt = gco2u(o)->metatable; - gray2black(o); /* udata are never gray */ - if (mt) markobject(g, mt); + markobject(g, mt); markobject(g, gco2u(o)->env); + gray2black(o); /* all pointers marked */ 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 */ + if (uv->v == &uv->u.value) /* closed? (open upvalues remain gray) */ + gray2black(o); /* make it black */ return; } case LUA_TFUNCTION: { @@ -93,8 +272,7 @@ static void reallymarkobject (global_State *g, GCObject *o) { break; } case LUA_TTABLE: { - gco2h(o)->gclist = g->gray; - g->gray = o; + linktable(gco2t(o), &g->gray); break; } case LUA_TTHREAD: { @@ -112,117 +290,187 @@ static void reallymarkobject (global_State *g, GCObject *o) { } -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); +/* +** mark metamethods for basic types +*/ +static void markmt (global_State *g) { + int i; + for (i=0; i < LUA_NUMTAGS; i++) + markobject(g, g->mt[i]); +} + + +/* +** mark all objects in list of being-finalized +*/ +static void markbeingfnz (global_State *g) { + GCObject *o; + for (o = g->tobefnz; o != NULL; o = gch(o)->next) { + makewhite(g, o); + reallymarkobject(g, o); } } -/* 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; - } - } +/* +** mark all values stored in marked open upvalues. (See comment in +** 'lstate.h'.) +*/ +static void remarkupvals (global_State *g) { + UpVal *uv; + for (uv = g->uvhead.u.l.next; uv != &g->uvhead; uv = uv->u.l.next) { + if (isgray(obj2gco(uv))) + markvalue(g, uv->v); } - 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 */ +/* +** mark root set and reset all gray lists, to start a new +** incremental (or full) collection +*/ +static void markroot (global_State *g) { + g->gray = g->grayagain = NULL; + g->weak = g->allweak = g->ephemeron = NULL; + markobject(g, g->mainthread); + markvalue(g, &g->l_registry); + markmt(g); + markbeingfnz(g); /* mark any finalizing object left from previous cycle */ +} + +/* }====================================================== */ + + +/* +** {====================================================== +** Traverse functions +** ======================================================= +*/ + +static void traverseweakvalue (global_State *g, Table *h) { + Node *n, *limit = gnodelast(h); + /* if there is array part, assume it may have white values (do not + traverse it just to check) */ + int hasclears = (h->sizearray > 0); + for (n = gnode(h, 0); n < limit; n++) { + checkdeadkey(n); + if (ttisnil(gval(n))) /* entry is empty? */ + removeentry(n); /* remove it */ else { lua_assert(!ttisnil(gkey(n))); - if (!weakkey) markvalue(g, gkey(n)); - if (!weakvalue) markvalue(g, gval(n)); + markvalue(g, gkey(n)); /* mark key */ + if (!hasclears && iscleared(gval(n))) /* is there a white value? */ + hasclears = 1; /* table will have to be cleared */ } } - return weakkey || weakvalue; + if (hasclears) + linktable(h, &g->weak); /* has to be cleared later */ + else /* no white values */ + linktable(h, &g->grayagain); /* no need to clean */ } -/* -** All marks are conditional because a GC may happen while the -** prototype is still being created -*/ -static void traverseproto (global_State *g, Proto *f) { +static int traverseephemeron (global_State *g, Table *h) { + int marked = 0; /* true if an object is marked in this traversal */ + int hasclears = 0; /* true if table has white keys */ + int prop = 0; /* true if table has entry "white-key -> white-value" */ + Node *n, *limit = gnodelast(h); 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]); + /* traverse array part (numeric keys are 'strong') */ + for (i = 0; i < h->sizearray; i++) { + if (valiswhite(&h->array[i])) { + marked = 1; + reallymarkobject(g, gcvalue(&h->array[i])); + } } - for (i=0; i<f->sizep; i++) { /* mark nested protos */ - if (f->p[i]) - markobject(g, f->p[i]); + /* traverse hash part */ + for (n = gnode(h, 0); n < limit; n++) { + checkdeadkey(n); + if (ttisnil(gval(n))) /* entry is empty? */ + removeentry(n); /* remove it */ + else if (iscleared(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 */ + } + else if (valiswhite(gval(n))) { /* value not marked yet? */ + marked = 1; + reallymarkobject(g, gcvalue(gval(n))); /* mark it now */ + } } - for (i=0; i<f->sizelocvars; i++) { /* mark local-variable names */ - if (f->locvars[i].varname) - stringmark(f->locvars[i].varname); + if (prop) + linktable(h, &g->ephemeron); /* have to propagate again */ + else if (hasclears) /* does table have white keys? */ + linktable(h, &g->allweak); /* may have to clean white keys */ + else /* no white keys */ + linktable(h, &g->grayagain); /* no need to clean */ + return marked; +} + + +static void traversestrongtable (global_State *g, Table *h) { + Node *n, *limit = gnodelast(h); + int i; + for (i = 0; i < h->sizearray; i++) /* traverse array part */ + markvalue(g, &h->array[i]); + for (n = gnode(h, 0); n < limit; n++) { /* traverse hash part */ + checkdeadkey(n); + if (ttisnil(gval(n))) /* entry is empty? */ + removeentry(n); /* remove it */ + else { + lua_assert(!ttisnil(gkey(n))); + markvalue(g, gkey(n)); /* mark key */ + markvalue(g, gval(n)); /* mark value */ + } } } +static int traversetable (global_State *g, Table *h) { + 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 */ + } + traversestrongtable(g, h); + return TRAVCOST + h->sizearray + (2 * sizenode(h)); +} + -static void traverseclosure (global_State *g, Closure *cl) { - markobject(g, cl->c.env); +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); + 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); + 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; +} + + +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 */ @@ -230,69 +478,49 @@ static void traverseclosure (global_State *g, Closure *cl) { } else { int i; - lua_assert(cl->l.nupvalues == cl->l.p->nups); - markobject(g, cl->l.p); + 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 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++) +static int traversestack (global_State *g, lua_State *L) { + StkId o = L->stack; + if (o == NULL) + return 1; /* stack not completely built yet */ + for (; o < L->top; o++) markvalue(g, o); - for (; o <= lim; o++) - setnilvalue(o); - checkstacksizes(l, lim); + if (g->gcstate == GCSatomic) { /* final traversal? */ + StkId lim = L->stack + L->stacksize; /* real end of stack */ + for (; o < lim; o++) /* clear not-marked stack slice */ + setnilvalue(o); + } + return TRAVCOST + cast_int(o - L->stack); } /* -** traverse one gray object, turning it to black. -** Returns `quantity' traversed. +** traverse one gray object, turning it to black (except for threads, +** which are always gray). +** Returns number of values traversed. */ -static l_mem propagatemark (global_State *g) { +static int propagatemark (global_State *g) { GCObject *o = g->gray; lua_assert(isgray(o)); gray2black(o); - switch (o->gch.tt) { + switch (gch(o)->tt) { case LUA_TTABLE: { - Table *h = gco2h(o); + Table *h = gco2t(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); + return traversetable(g, 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); + return traverseclosure(g, cl); } case LUA_TTHREAD: { lua_State *th = gco2th(o); @@ -300,306 +528,476 @@ static l_mem propagatemark (global_State *g) { 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; + return traversestack(g, th); } 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; + return traverseproto(g, p); } 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; +static void propagateall (global_State *g) { + while (g->gray) propagatemark(g); } +static void propagatelist (global_State *g, GCObject *l) { + lua_assert(g->gray == NULL); /* no grays left */ + g->gray = l; + propagateall(g); /* traverse all elements from 'l' */ +} + /* -** 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 +** retraverse all gray lists. Because tables may be reinserted in other +** lists when traversed, traverse the original lists to avoid traversing +** twice the same table (which is not wrong, but inefficient) */ -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)))); +static void retraversegrays (global_State *g) { + GCObject *weak = g->weak; /* save original lists */ + GCObject *grayagain = g->grayagain; + GCObject *ephemeron = g->ephemeron; + g->weak = g->grayagain = g->ephemeron = NULL; + propagateall(g); /* traverse main gray list */ + propagatelist(g, grayagain); + propagatelist(g, weak); + propagatelist(g, ephemeron); +} + + +static void convergeephemerons (global_State *g) { + int changed; + do { + GCObject *w; + GCObject *next = g->ephemeron; /* get ephemeron list */ + g->ephemeron = NULL; /* tables will return to this list when traversed */ + changed = 0; + while ((w = next) != NULL) { + next = gco2t(w)->gclist; + if (traverseephemeron(g, gco2t(w))) { /* traverse marked some value? */ + propagateall(g); /* propagate changes */ + changed = 1; /* will have to revisit all ephemeron tables */ + } + } + } while (changed); } +/* }====================================================== */ + + +/* +** {====================================================== +** Sweep Functions +** ======================================================= +*/ + /* -** clear collected entries from weaktables +** clear entries with unmarked keys from all weaktables in list 'l' up +** to element 'f' */ -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 */ +static void clearkeys (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)))) { + setnilvalue(gval(n)); /* remove value ... */ + removeentry(n); /* and remove entry from table */ } } - 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))) { + } +} + + +/* +** clear entries with unmarked values from all weaktables in list 'l' up +** to element 'f' +*/ +static void clearvalues (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? */ + setnilvalue(o); /* remove value */ + } + for (n = gnode(h, 0); n < limit; n++) { + if (!ttisnil(gval(n)) && iscleared(gval(n))) { setnilvalue(gval(n)); /* remove value ... */ - removeentry(n); /* remove entry from table */ + removeentry(n); /* and remove entry from table */ } } - l = h->gclist; } } static void freeobj (lua_State *L, GCObject *o) { - switch (o->gch.tt) { + switch (gch(o)->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_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: { 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); + + +/* +** sweep the (open) upvalues of a thread and resize its stack and +** list of call-info structures. +*/ +static void sweepthread (lua_State *L, lua_State *L1) { + if (L1->stack == NULL) return; /* stack not completely built yet */ + sweepwholelist(L, &L1->openupval); /* sweep open upvalues */ + luaE_freeCI(L1); /* free extra CallInfo slots */ + /* should not change the stack during an emergency gc cycle */ + if (G(L)->gckind != KGC_EMERGENCY) + luaD_shrinkstack(L1); +} +/* +** sweep at most 'count' elements from a list of GCObjects erasing dead +** objects, where a dead (not alive) object is one marked with the "old" +** (non current) white and not fixed. +** In non-generational mode, change all non-dead objects back to white, +** preparing for next collection cycle. +** In generational mode, keep black objects black, and also mark them as +** old; stop when hitting an old object, as all objects after that +** one will be old too. +** When object is a thread, sweep its list of open upvalues too. +*/ 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); + 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 */ + tostop = bitmask(OLDBIT); /* do not sweep old generation */ + } + else { /* normal mode */ + toclear = maskcolors; /* clear all color bits + old bit */ + toset = luaC_white(g); /* make object white */ + tostop = 0; /* do not stop */ + } + while (*p != NULL && count-- > 0) { + GCObject *curr = *p; + int marked = gch(curr)->marked; + if (isdeadm(ow, marked)) { /* is 'curr' dead? */ + *p = gch(curr)->next; /* remove 'curr' from list */ + freeobj(L, curr); /* erase 'curr' */ + } + else { + 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; } +/* }====================================================== */ + + +/* +** {====================================================== +** Finalization +** ======================================================= +*/ 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); + if (g->gckind != KGC_EMERGENCY) { /* do not change sizes in emergency */ + int hs = g->strt.size / 2; /* half the size of the string table */ + if (g->strt.nuse < cast(lu_int32, hs)) /* using less than that half? */ + luaS_resize(L, hs); /* halve its size */ + luaZ_freebuffer(L, &g->buff); /* free concatenation buffer */ } } -static void GCTM (lua_State *L) { +static GCObject *udata2finalize (global_State *g) { + GCObject *o = g->tobefnz; /* get first element */ + lua_assert(isfinalized(o)); + g->tobefnz = gch(o)->next; /* remove it from 'tobefnz' list */ + gch(o)->next = g->allgc; /* return it to 'allgc' list */ + g->allgc = o; + resetbit(gch(o)->marked, SEPARATED); /* mark that it is not in 'tobefnz' */ + lua_assert(!isold(o)); /* see MOVE OLD rule */ + if (!keepinvariant(g)) /* not keeping invariant? */ + makewhite(g, o); /* "sweep" object */ + return o; +} + + +static void dothecall (lua_State *L, void *ud) { + UNUSED(ud); + luaD_call(L, L->top - 2, 0, 0); +} + + +static void GCTM (lua_State *L, int propagateerrors) { 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) { + TValue v; + setgcovalue(L, &v, udata2finalize(g)); + tm = luaT_gettmbyobj(L, &v, TM_GC); + if (tm != NULL && ttisfunction(tm)) { /* is there a finalizer? */ + int status; 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); + int running = g->gcrunning; + L->allowhook = 0; /* stop debug hooks during GC metamethod */ + g->gcrunning = 0; /* avoid GC steps */ + setobj2s(L, L->top, tm); /* push finalizer... */ + setobj2s(L, L->top + 1, &v); /* ... and its argument */ + L->top += 2; /* and (next line) call the finalizer */ + status = luaD_pcall(L, dothecall, NULL, savestack(L, L->top - 2), 0); L->allowhook = oldah; /* restore hooks */ - g->GCthreshold = oldt; /* restore threshold */ + 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)); + status = LUA_ERRGCMM; /* error in __gc metamethod */ + } + luaD_throw(L, status); /* re-send error */ + } } } /* -** Call all GC tag methods +** move all unreachable objects (or 'all' objects) that need +** finalization from list 'finobj' to list 'tobefnz' (to be finalized) */ -void luaC_callGCTM (lua_State *L) { - while (G(L)->tmudata) - GCTM(L); +static void separatetobefnz (lua_State *L, int all) { + global_State *g = G(L); + GCObject **p = &g->finobj; + GCObject *curr; + GCObject **lastnext = &g->tobefnz; + /* find last 'next' field in 'tobefnz' list (to add elements in its end) */ + while (*lastnext != NULL) + lastnext = &gch(*lastnext)->next; + while ((curr = *p) != NULL) { /* traverse all finalizable objects */ + lua_assert(!isfinalized(curr)); + lua_assert(testbit(gch(curr)->marked, SEPARATED)); + if (!(all || iswhite(curr))) /* not being collected? */ + p = &gch(curr)->next; /* don't bother with it */ + else { + l_setbit(gch(curr)->marked, FINALIZEDBIT); /* won't be finalized again */ + *p = gch(curr)->next; /* remove 'curr' from 'finobj' list */ + gch(curr)->next = *lastnext; /* link at the end of 'tobefnz' list */ + *lastnext = curr; + lastnext = &gch(curr)->next; + } + } } -void luaC_freeall (lua_State *L) { +/* +** if object 'o' has a finalizer, remove it from 'allgc' list (must +** search the list to find it) and link it in 'finobj' list. +*/ +void luaC_checkfinalizer (lua_State *L, GCObject *o, Table *mt) { 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]); + if (testbit(gch(o)->marked, SEPARATED) || /* obj. is already separated... */ + isfinalized(o) || /* ... or is finalized... */ + gfasttm(g, mt, TM_GC) == NULL) /* or has no finalizer? */ + 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' */ + g->finobj = o; + l_setbit(gch(o)->marked, SEPARATED); /* mark it as such */ + resetoldbit(o); /* see MOVE OLD rule */ + } } +/* }====================================================== */ -static void markmt (global_State *g) { - int i; - for (i=0; i<NUM_TAGS; i++) - if (g->mt[i]) markobject(g, g->mt[i]); -} +/* +** {====================================================== +** GC control +** ======================================================= +*/ -/* mark root set */ -static void markroot (lua_State *L) { + +#define sweepphases \ + (bitmask(GCSsweepstring) | bitmask(GCSsweepudata) | bitmask(GCSsweep)) + +/* +** change GC mode +*/ +void luaC_changemode (lua_State *L, int mode) { 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; + if (mode == g->gckind) return; /* nothing to change */ + if (mode == KGC_GEN) { /* change to generational mode */ + /* make sure gray lists are consistent */ + luaC_runtilstate(L, bitmask(GCSpropagate)); + g->lastmajormem = 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; + luaC_runtilstate(L, ~sweepphases); + } } -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); +/* +** call all pending finalizers +*/ +static void callallpendingfinalizers (lua_State *L, int propagateerrors) { + global_State *g = G(L); + while (g->tobefnz) { + resetoldbit(g->tobefnz); + GCTM(L, propagateerrors); } } +void luaC_freeallobjects (lua_State *L) { + global_State *g = G(L); + int i; + separatetobefnz(L, 1); /* separate all objects with finalizers */ + lua_assert(g->finobj == NULL); + callallpendingfinalizers(L, 0); + g->currentwhite = WHITEBITS; /* this "white" makes all objects look dead */ + g->gckind = KGC_NORMAL; + sweepwholelist(L, &g->finobj); /* finalizers can create objs. in 'finobj' */ + sweepwholelist(L, &g->allgc); + for (i = 0; i < g->strt.size; i++) /* free all string lists */ + sweepwholelist(L, &g->strt.hash[i]); + lua_assert(g->strt.nuse == 0); +} + + 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; + GCObject *origweak, *origall; 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; + /* registry and global metatables may be changed by API */ + markvalue(g, &g->l_registry); + markmt(g); /* mark basic metatables */ + /* remark occasional upvalues of (maybe) dead threads */ + remarkupvals(g); + /* traverse objects caught by write barrier and by 'remarkupvals' */ + retraversegrays(g); + 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); + origweak = g->weak; origall = g->allweak; + separatetobefnz(L, 0); /* separate objects to be finalized */ + markbeingfnz(g); /* mark userdata that will be finalized */ + propagateall(g); /* remark, to propagate `preserveness' */ + 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 */ + /* clear values from resurrected weak tables */ + clearvalues(g->weak, origweak); + clearvalues(g->allweak, origall); + g->sweepstrgc = 0; /* prepare to sweep strings */ g->gcstate = GCSsweepstring; - g->estimate = g->totalbytes - udsize; /* first estimate */ + g->currentwhite = cast_byte(otherwhite(g)); /* flip current white */ + /*lua_checkmemory(L);*/ } 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; + if (!isgenerational(g)) + markroot(g); /* start a new collection */ + /* in any case, root must be marked */ + lua_assert(!iswhite(obj2gco(g->mainthread)) + && !iswhite(gcvalue(&g->l_registry))); + g->gcstate = GCSpropagate; + return GCROOTCOST; } case GCSpropagate: { if (g->gray) return propagatemark(g); else { /* no more `gray' objects */ - atomic(L); /* finish mark phase */ - return 0; + g->gcstate = GCSatomic; /* finish mark phase */ + atomic(L); + return GCATOMICCOST; } } 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; + 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 */ + g->gcstate = GCSsweepudata; + return 0; + } } - 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 */ + case GCSsweepudata: { + if (*g->sweepgc) { + g->sweepgc = sweeplist(L, g->sweepgc, GCSWEEPMAX); + return GCSWEEPMAX*GCSWEEPCOST; + } + else { + g->sweepgc = &g->allgc; /* go to next phase */ + g->gcstate = GCSsweep; + return GCSWEEPCOST; } - 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; + } + case GCSsweep: { + if (*g->sweepgc) { + g->sweepgc = sweeplist(L, g->sweepgc, GCSWEEPMAX); + return GCSWEEPMAX*GCSWEEPCOST; } else { - g->gcstate = GCSpause; /* end collection */ - g->gcdept = 0; - return 0; + /* sweep main thread */ + GCObject *mt = obj2gco(g->mainthread); + sweeplist(L, &mt, 1); + checkSizes(L); + g->gcstate = GCSpause; /* finish collection */ + return GCSWEEPCOST; } } default: lua_assert(0); return 0; @@ -607,105 +1005,99 @@ static l_mem singlestep (lua_State *L) { } -void luaC_step (lua_State *L) { +/* +** advances the garbage collector until it reaches a state allowed +** by 'statemask' +*/ +void luaC_runtilstate (lua_State *L, int statesmask) { 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); - } + while (!testbit(statesmask, g->gcstate)) + singlestep(L); } -void luaC_fullgc (lua_State *L) { +static void generationalcollection (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); + if (g->lastmajormem == 0) { /* signal for another major collection? */ + luaC_fullgc(L, 0); /* perform a full regular collection */ + g->lastmajormem = gettotalbytes(g); /* update control */ } - markroot(L); - while (g->gcstate != GCSpause) { - singlestep(L); + else { + 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 */ } - setthreshold(g); + luaE_setdebt(g, stddebt(g)); } -void luaC_barrierf (lua_State *L, GCObject *o, GCObject *v) { +static void step (lua_State *L) { 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 */ + l_mem lim = g->gcstepmul; /* how much to work */ + 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); + else + luaE_setdebt(g, stddebt(g)); } -void luaC_barrierback (lua_State *L, Table *t) { +/* +** performs a basic GC step even if the collector is stopped +*/ +void luaC_forcestep (lua_State *L) { 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; + 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 */ } -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; +/* +** performs a basic GC step only if collector is running +*/ +void luaC_step (lua_State *L) { + if (G(L)->gcrunning) luaC_forcestep(L); } -void luaC_linkupval (lua_State *L, UpVal *uv) { +/* +** performs a full GC cycle; if "isemergency", does not call +** finalizers (which could change stack positions) +*/ +void luaC_fullgc (lua_State *L, int isemergency) { 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); - } + int origkind = g->gckind; + lua_assert(origkind != KGC_EMERGENCY); + if (!isemergency) /* do not run finalizers during emergency GC */ + callallpendingfinalizers(L, 1); + if (keepinvariant(g)) { /* marking phase? */ + /* 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; + } + 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 */ + luaC_runtilstate(L, ~bitmask(GCSpause)); + luaC_runtilstate(L, bitmask(GCSpause)); + if (origkind == KGC_GEN) { /* generational mode? */ + /* generational mode must always start in propagate phase */ + luaC_runtilstate(L, bitmask(GCSpropagate)); } + g->gckind = origkind; + luaE_setdebt(g, stddebt(g)); + if (!isemergency) /* do not run finalizers during emergency GC */ + callallpendingfinalizers(L, 1); } +/* }====================================================== */ + + |