+++ /dev/null
-/*
-** $Id: lgc.c,v 2.212 2016/03/31 19:02:03 roberto Exp $
-** Garbage Collector
-** See Copyright Notice in lua.h
-*/
-
-#define lgc_c
-#define LUA_CORE
-
-#include "lprefix.h"
-
-
-#include <string.h>
-
-#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"
-
-
-/*
-** internal state for collector while inside the atomic phase. The
-** collector should never be in this state while running regular code.
-*/
-#define GCSinsideatomic (GCSpause + 1)
-
-/*
-** 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 (cast_int((GCSTEPSIZE / GCSWEEPCOST) / 4))
-
-/* cost of calling one finalizer */
-#define GCFINALIZECOST GCSWEEPCOST
-
-
-/*
-** 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 100
-
-
-/*
-** 'makewhite' erases all color bits then sets only the current white
-** bit
-*/
-#define maskcolors (~(bitmask(BLACKBIT) | WHITEBITS))
-#define makewhite(g,x) \
- (x->marked = cast_byte((x->marked & maskcolors) | luaC_white(g)))
-
-#define white2gray(x) resetbits(x->marked, WHITEBITS)
-#define black2gray(x) resetbit(x->marked, BLACKBIT)
-
-
-#define valiswhite(x) (iscollectable(x) && iswhite(gcvalue(x)))
-
-#define checkdeadkey(n) lua_assert(!ttisdeadkey(gkey(n)) || ttisnil(gval(n)))
-
-
-#define checkconsistency(obj) \
- lua_longassert(!iscollectable(obj) || righttt(obj))
-
-
-#define markvalue(g,o) { checkconsistency(o); \
- if (valiswhite(o)) reallymarkobject(g,gcvalue(o)); }
-
-#define markobject(g,t) { if (iswhite(t)) reallymarkobject(g, obj2gco(t)); }
-
-/*
-** mark an object that can be NULL (either because it is really optional,
-** or it was stripped as debug info, or inside an uncompleted structure)
-*/
-#define markobjectN(g,t) { if (t) markobject(g,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)))
-
-
-/*
-** link collectable object 'o' into list pointed by 'p'
-*/
-#define linkgclist(o,p) ((o)->gclist = (p), (p) = obj2gco(o))
-
-
-/*
-** If key is not marked, mark its entry as dead. This allows key to be
-** collected, but keeps its entry in the table. A dead node is needed
-** when Lua looks up for a key (it may be part of a chain) and when
-** traversing a weak table (key might be removed from the table during
-** traversal). Other places never manipulate dead keys, because its
-** associated nil value is enough to signal that the entry is logically
-** empty.
-*/
-static void removeentry (Node *n) {
- lua_assert(ttisnil(gval(n)));
- if (valiswhite(gkey(n)))
- setdeadvalue(wgkey(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 (global_State *g, const TValue *o) {
- if (!iscollectable(o)) return 0;
- else if (ttisstring(o)) {
- markobject(g, tsvalue(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. (If in sweep phase, clear the black
-** object to white [sweep it] to avoid other barrier calls for this
-** same 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));
- 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.
-*/
-void luaC_barrierback_ (lua_State *L, Table *t) {
- global_State *g = G(L);
- lua_assert(isblack(t) && !isdead(g, t));
- black2gray(t); /* make table gray (again) */
- linkgclist(t, g->grayagain);
-}
-
-
-/*
-** barrier for assignments to closed upvalues. Because upvalues are
-** shared among closures, it is impossible to know the color of all
-** closures pointing to it. So, we assume that the object being assigned
-** must be marked.
-*/
-void luaC_upvalbarrier_ (lua_State *L, UpVal *uv) {
- global_State *g = G(L);
- GCObject *o = gcvalue(uv->v);
- lua_assert(!upisopen(uv)); /* ensured by macro luaC_upvalbarrier */
- if (keepinvariant(g))
- markobject(g, o);
-}
-
-
-void luaC_fix (lua_State *L, GCObject *o) {
- global_State *g = G(L);
- lua_assert(g->allgc == o); /* object must be 1st in 'allgc' list! */
- white2gray(o); /* they will be gray forever */
- g->allgc = o->next; /* remove object from 'allgc' list */
- o->next = g->fixedgc; /* link it to 'fixedgc' list */
- g->fixedgc = o;
-}
-
-
-/*
-** create a new collectable object (with given type and size) and link
-** it to 'allgc' list.
-*/
-GCObject *luaC_newobj (lua_State *L, int tt, size_t sz) {
- global_State *g = G(L);
- GCObject *o = cast(GCObject *, luaM_newobject(L, novariant(tt), sz));
- o->marked = luaC_white(g);
- o->tt = tt;
- o->next = g->allgc;
- g->allgc = o;
- return o;
-}
-
-/* }====================================================== */
-
-
-
-/*
-** {======================================================
-** Mark functions
-** =======================================================
-*/
-
-
-/*
-** 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) {
- reentry:
- white2gray(o);
- switch (o->tt) {
- case LUA_TSHRSTR: {
- gray2black(o);
- g->GCmemtrav += sizelstring(gco2ts(o)->shrlen);
- break;
- }
- case LUA_TLNGSTR: {
- gray2black(o);
- g->GCmemtrav += sizelstring(gco2ts(o)->u.lnglen);
- break;
- }
- case LUA_TUSERDATA: {
- TValue uvalue;
- markobjectN(g, gco2u(o)->metatable); /* mark its metatable */
- gray2black(o);
- g->GCmemtrav += sizeudata(gco2u(o));
- getuservalue(g->mainthread, gco2u(o), &uvalue);
- if (valiswhite(&uvalue)) { /* markvalue(g, &uvalue); */
- o = gcvalue(&uvalue);
- goto reentry;
- }
- break;
- }
- case LUA_TLCL: {
- linkgclist(gco2lcl(o), g->gray);
- break;
- }
- case LUA_TCCL: {
- linkgclist(gco2ccl(o), g->gray);
- break;
- }
- case LUA_TTABLE: {
- linkgclist(gco2t(o), g->gray);
- break;
- }
- case LUA_TTHREAD: {
- linkgclist(gco2th(o), g->gray);
- break;
- }
- case LUA_TPROTO: {
- linkgclist(gco2p(o), g->gray);
- break;
- }
- default: lua_assert(0); break;
- }
-}
-
-
-/*
-** mark metamethods for basic types
-*/
-static void markmt (global_State *g) {
- int i;
- for (i=0; i < LUA_NUMTAGS; i++)
- markobjectN(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 = o->next)
- markobject(g, o);
-}
-
-
-/*
-** Mark all values stored in marked open upvalues from non-marked threads.
-** (Values from marked threads were already marked when traversing the
-** thread.) Remove from the list threads that no longer have upvalues and
-** not-marked threads.
-*/
-static void remarkupvals (global_State *g) {
- lua_State *thread;
- lua_State **p = &g->twups;
- while ((thread = *p) != NULL) {
- lua_assert(!isblack(thread)); /* threads are never black */
- if (isgray(thread) && thread->openupval != NULL)
- p = &thread->twups; /* keep marked thread with upvalues in the list */
- else { /* thread is not marked or without upvalues */
- UpVal *uv;
- *p = thread->twups; /* remove thread from the list */
- thread->twups = thread; /* mark that it is out of list */
- for (uv = thread->openupval; uv != NULL; uv = uv->u.open.next) {
- if (uv->u.open.touched) {
- markvalue(g, uv->v); /* remark upvalue's value */
- uv->u.open.touched = 0;
- }
- }
- }
- }
-}
-
-
-/*
-** mark root set and reset all gray lists, to start a new collection
-*/
-static void restartcollection (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
-** =======================================================
-*/
-
-/*
-** Traverse a table with weak values and link it to proper list. During
-** propagate phase, keep it in 'grayagain' list, to be revisited in the
-** atomic phase. In the atomic phase, if table has any white value,
-** put it in 'weak' list, to be cleared.
-*/
-static void traverseweakvalue (global_State *g, Table *h) {
- Node *n, *limit = gnodelast(h);
- /* if there is array part, assume it may have white values (it is not
- worth traversing it now just to check) */
- int hasclears = (h->sizearray > 0);
- 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 */
- if (!hasclears && iscleared(g, gval(n))) /* is there a white value? */
- hasclears = 1; /* table will have to be cleared */
- }
- }
- if (g->gcstate == GCSpropagate)
- linkgclist(h, g->grayagain); /* must retraverse it in atomic phase */
- else if (hasclears)
- linkgclist(h, g->weak); /* has to be cleared later */
-}
-
-
-/*
-** Traverse an ephemeron table and link it to proper list. Returns true
-** iff any object was marked during this traversal (which implies that
-** convergence has to continue). During propagation phase, keep table
-** in 'grayagain' list, to be visited again in the atomic phase. In
-** the atomic phase, if table has any white->white entry, it has to
-** be revisited during ephemeron convergence (as that key may turn
-** black). Otherwise, if it has any white key, table has to be cleared
-** (in the atomic phase).
-*/
-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 hasww = 0; /* true if table has entry "white-key -> white-value" */
- Node *n, *limit = gnodelast(h);
- unsigned int i;
- /* traverse array part */
- for (i = 0; i < h->sizearray; i++) {
- if (valiswhite(&h->array[i])) {
- marked = 1;
- reallymarkobject(g, gcvalue(&h->array[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(g, gkey(n))) { /* key is not marked (yet)? */
- hasclears = 1; /* table must be cleared */
- if (valiswhite(gval(n))) /* value not marked yet? */
- hasww = 1; /* white-white entry */
- }
- else if (valiswhite(gval(n))) { /* value not marked yet? */
- marked = 1;
- reallymarkobject(g, gcvalue(gval(n))); /* mark it now */
- }
- }
- /* link table into proper list */
- if (g->gcstate == GCSpropagate)
- linkgclist(h, g->grayagain); /* must retraverse it in atomic phase */
- else if (hasww) /* table has white->white entries? */
- linkgclist(h, g->ephemeron); /* have to propagate again */
- else if (hasclears) /* table has white keys? */
- linkgclist(h, g->allweak); /* may have to clean white keys */
- return marked;
-}
-
-
-static void traversestrongtable (global_State *g, Table *h) {
- Node *n, *limit = gnodelast(h);
- unsigned 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 lu_mem traversetable (global_State *g, Table *h) {
- const char *weakkey, *weakvalue;
- const TValue *mode = gfasttm(g, h->metatable, TM_MODE);
- markobjectN(g, h->metatable);
- 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(h); /* keep table gray */
- if (!weakkey) /* strong keys? */
- traverseweakvalue(g, h);
- else if (!weakvalue) /* strong values? */
- traverseephemeron(g, h);
- else /* all weak */
- linkgclist(h, g->allweak); /* nothing to traverse now */
- }
- else /* not weak */
- traversestrongtable(g, h);
- return sizeof(Table) + sizeof(TValue) * h->sizearray +
- sizeof(Node) * cast(size_t, sizenode(h));
-}
-
-
-/*
-** Traverse a prototype. (While a prototype is being build, its
-** arrays can be larger than needed; the extra slots are filled with
-** NULL, so the use of 'markobjectN')
-*/
-static int traverseproto (global_State *g, Proto *f) {
- int i;
- if (f->cache && iswhite(f->cache))
- f->cache = NULL; /* allow cache to be collected */
- markobjectN(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 */
- markobjectN(g, f->upvalues[i].name);
- for (i = 0; i < f->sizep; i++) /* mark nested protos */
- markobjectN(g, f->p[i]);
- for (i = 0; i < f->sizelocvars; i++) /* mark local-variable names */
- markobjectN(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 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);
-}
-
-/*
-** open upvalues point to values in a thread, so those values should
-** be marked when the thread is traversed except in the atomic phase
-** (because then the value cannot be changed by the thread and the
-** thread may not be traversed again)
-*/
-static lu_mem traverseLclosure (global_State *g, LClosure *cl) {
- int i;
- markobjectN(g, cl->p); /* mark its prototype */
- for (i = 0; i < cl->nupvalues; i++) { /* mark its upvalues */
- UpVal *uv = cl->upvals[i];
- if (uv != NULL) {
- if (upisopen(uv) && g->gcstate != GCSinsideatomic)
- uv->u.open.touched = 1; /* can be marked in 'remarkupvals' */
- else
- markvalue(g, uv->v);
- }
- }
- return sizeLclosure(cl->nupvalues);
-}
-
-
-static lu_mem traversethread (global_State *g, lua_State *th) {
- StkId o = th->stack;
- if (o == NULL)
- return 1; /* stack not completely built yet */
- lua_assert(g->gcstate == GCSinsideatomic ||
- th->openupval == NULL || isintwups(th));
- for (; o < th->top; o++) /* mark live elements in the stack */
- markvalue(g, o);
- if (g->gcstate == GCSinsideatomic) { /* final traversal? */
- StkId lim = th->stack + th->stacksize; /* real end of stack */
- for (; o < lim; o++) /* clear not-marked stack slice */
- setnilvalue(o);
- /* 'remarkupvals' may have removed thread from 'twups' list */
- if (!isintwups(th) && th->openupval != NULL) {
- th->twups = g->twups; /* link it back to the list */
- g->twups = th;
- }
- }
- else if (g->gckind != KGC_EMERGENCY)
- luaD_shrinkstack(th); /* do not change stack in emergency cycle */
- return (sizeof(lua_State) + sizeof(TValue) * th->stacksize +
- sizeof(CallInfo) * th->nci);
-}
-
-
-/*
-** traverse one gray object, turning it to black (except for threads,
-** which are always gray).
-*/
-static void propagatemark (global_State *g) {
- lu_mem size;
- GCObject *o = g->gray;
- lua_assert(isgray(o));
- gray2black(o);
- switch (o->tt) {
- case LUA_TTABLE: {
- Table *h = gco2t(o);
- 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_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; /* remove from 'gray' list */
- linkgclist(th, g->grayagain); /* insert into 'grayagain' list */
- black2gray(o);
- size = traversethread(g, th);
- break;
- }
- case LUA_TPROTO: {
- Proto *p = gco2p(o);
- g->gray = p->gclist; /* remove from 'gray' list */
- size = traverseproto(g, p);
- break;
- }
- default: lua_assert(0); return;
- }
- g->GCmemtrav += size;
-}
-
-
-static void propagateall (global_State *g) {
- while (g->gray) propagatemark(g);
-}
-
-
-static void convergeephemerons (global_State *g) {
- int changed;
- do {
- GCObject *w;
- GCObject *next = g->ephemeron; /* get ephemeron list */
- g->ephemeron = NULL; /* tables may 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 entries with unmarked keys from all weaktables in list 'l' up
-** to element '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(g, gkey(n)))) {
- setnilvalue(gval(n)); /* remove value ... */
- removeentry(n); /* and remove entry from table */
- }
- }
- }
-}
-
-
-/*
-** clear entries with unmarked values from all weaktables in list 'l' up
-** to element '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);
- unsigned int i;
- for (i = 0; i < h->sizearray; i++) {
- TValue *o = &h->array[i];
- if (iscleared(g, o)) /* value was collected? */
- setnilvalue(o); /* remove value */
- }
- for (n = gnode(h, 0); n < limit; n++) {
- if (!ttisnil(gval(n)) && iscleared(g, gval(n))) {
- setnilvalue(gval(n)); /* remove value ... */
- removeentry(n); /* and remove entry from table */
- }
- }
- }
-}
-
-
-void luaC_upvdeccount (lua_State *L, UpVal *uv) {
- lua_assert(uv->refcount > 0);
- uv->refcount--;
- if (uv->refcount == 0 && !upisopen(uv))
- luaM_free(L, uv);
-}
-
-
-static void freeLclosure (lua_State *L, LClosure *cl) {
- int i;
- for (i = 0; i < cl->nupvalues; i++) {
- UpVal *uv = cl->upvals[i];
- if (uv)
- luaC_upvdeccount(L, uv);
- }
- luaM_freemem(L, cl, sizeLclosure(cl->nupvalues));
-}
-
-
-static void freeobj (lua_State *L, GCObject *o) {
- switch (o->tt) {
- case LUA_TPROTO: luaF_freeproto(L, gco2p(o)); break;
- case LUA_TLCL: {
- freeLclosure(L, gco2lcl(o));
- break;
- }
- case LUA_TCCL: {
- luaM_freemem(L, o, sizeCclosure(gco2ccl(o)->nupvalues));
- 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_TSHRSTR:
- luaS_remove(L, gco2ts(o)); /* remove it from hash table */
- luaM_freemem(L, o, sizelstring(gco2ts(o)->shrlen));
- break;
- case LUA_TLNGSTR: {
- luaM_freemem(L, o, sizelstring(gco2ts(o)->u.lnglen));
- 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 at most 'count' elements from a list of GCObjects erasing dead
-** objects, where a dead object is one marked with the old (non current)
-** white; change all non-dead objects back to white, preparing for next
-** collection cycle. Return where to continue the traversal or NULL if
-** list is finished.
-*/
-static GCObject **sweeplist (lua_State *L, GCObject **p, lu_mem count) {
- global_State *g = G(L);
- int ow = otherwhite(g);
- int white = luaC_white(g); /* current white */
- while (*p != NULL && count-- > 0) {
- GCObject *curr = *p;
- int marked = curr->marked;
- if (isdeadm(ow, marked)) { /* is 'curr' dead? */
- *p = curr->next; /* remove 'curr' from list */
- freeobj(L, curr); /* erase 'curr' */
- }
- else { /* change mark to 'white' */
- curr->marked = cast_byte((marked & maskcolors) | white);
- p = &curr->next; /* go to next element */
- }
- }
- return (*p == NULL) ? NULL : p;
-}
-
-
-/*
-** sweep a list until a live object (or end of list)
-*/
-static GCObject **sweeptolive (lua_State *L, GCObject **p) {
- GCObject **old = p;
- do {
- p = sweeplist(L, p, 1);
- } while (p == old);
- return p;
-}
-
-/* }====================================================== */
-
-
-/*
-** {======================================================
-** Finalization
-** =======================================================
-*/
-
-/*
-** If possible, shrink string table
-*/
-static void checkSizes (lua_State *L, global_State *g) {
- if (g->gckind != KGC_EMERGENCY) {
- l_mem olddebt = g->GCdebt;
- if (g->strt.nuse < g->strt.size / 4) /* string table too big? */
- luaS_resize(L, g->strt.size / 2); /* shrink it a little */
- g->GCestimate += g->GCdebt - olddebt; /* update estimate */
- }
-}
-
-
-static GCObject *udata2finalize (global_State *g) {
- GCObject *o = g->tobefnz; /* get first element */
- lua_assert(tofinalize(o));
- g->tobefnz = o->next; /* remove it from 'tobefnz' list */
- o->next = g->allgc; /* return it to 'allgc' list */
- g->allgc = o;
- resetbit(o->marked, FINALIZEDBIT); /* object is "normal" again */
- if (issweepphase(g))
- makewhite(g, o); /* "sweep" object */
- return o;
-}
-
-
-static void dothecall (lua_State *L, void *ud) {
- UNUSED(ud);
- luaD_callnoyield(L, L->top - 2, 0);
-}
-
-
-static void GCTM (lua_State *L, int propagateerrors) {
- global_State *g = G(L);
- const TValue *tm;
- 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;
- 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->gcrunning = running; /* restore state */
- if (status != LUA_OK && propagateerrors) { /* error while running __gc? */
- 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-throw error */
- }
- }
-}
-
-
-/*
-** call a few (up to 'g->gcfinnum') finalizers
-*/
-static int runafewfinalizers (lua_State *L) {
- global_State *g = G(L);
- unsigned int i;
- lua_assert(!g->tobefnz || g->gcfinnum > 0);
- for (i = 0; g->tobefnz && i < g->gcfinnum; i++)
- GCTM(L, 1); /* call one finalizer */
- g->gcfinnum = (!g->tobefnz) ? 0 /* nothing more to finalize? */
- : g->gcfinnum * 2; /* else call a few more next time */
- return i;
-}
-
-
-/*
-** call all pending finalizers
-*/
-static void callallpendingfinalizers (lua_State *L) {
- global_State *g = G(L);
- while (g->tobefnz)
- GCTM(L, 0);
-}
-
-
-/*
-** find last 'next' field in list 'p' list (to add elements in its end)
-*/
-static GCObject **findlast (GCObject **p) {
- while (*p != NULL)
- p = &(*p)->next;
- return p;
-}
-
-
-/*
-** move all unreachable objects (or 'all' objects) that need
-** finalization from list 'finobj' to list 'tobefnz' (to be finalized)
-*/
-static void separatetobefnz (global_State *g, int all) {
- GCObject *curr;
- GCObject **p = &g->finobj;
- GCObject **lastnext = findlast(&g->tobefnz);
- while ((curr = *p) != NULL) { /* traverse all finalizable objects */
- lua_assert(tofinalize(curr));
- if (!(iswhite(curr) || all)) /* not being collected? */
- p = &curr->next; /* don't bother with it */
- else {
- *p = curr->next; /* remove 'curr' from 'finobj' list */
- curr->next = *lastnext; /* link at the end of 'tobefnz' list */
- *lastnext = curr;
- lastnext = &curr->next;
- }
- }
-}
-
-
-/*
-** 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);
- if (tofinalize(o) || /* obj. is already marked... */
- gfasttm(g, mt, TM_GC) == NULL) /* or has no finalizer? */
- return; /* nothing to be done */
- else { /* move 'o' to 'finobj' list */
- GCObject **p;
- if (issweepphase(g)) {
- makewhite(g, o); /* "sweep" object 'o' */
- if (g->sweepgc == &o->next) /* should not remove 'sweepgc' object */
- g->sweepgc = sweeptolive(L, g->sweepgc); /* change 'sweepgc' */
- }
- /* search for pointer pointing to 'o' */
- for (p = &g->allgc; *p != o; p = &(*p)->next) { /* empty */ }
- *p = o->next; /* remove 'o' from 'allgc' list */
- o->next = g->finobj; /* link it in 'finobj' list */
- g->finobj = o;
- l_setbit(o->marked, FINALIZEDBIT); /* mark it as such */
- }
-}
-
-/* }====================================================== */
-
-
-
-/*
-** {======================================================
-** GC control
-** =======================================================
-*/
-
-
-/*
-** Set a reasonable "time" to wait before starting a new GC cycle; cycle
-** will start when memory use hits threshold. (Division by 'estimate'
-** should be OK: it cannot be zero (because Lua cannot even start with
-** less than PAUSEADJ bytes).
-*/
-static void setpause (global_State *g) {
- l_mem threshold, debt;
- l_mem estimate = g->GCestimate / PAUSEADJ; /* adjust 'estimate' */
- lua_assert(estimate > 0);
- threshold = (g->gcpause < MAX_LMEM / estimate) /* overflow? */
- ? estimate * g->gcpause /* no overflow */
- : MAX_LMEM; /* overflow; truncate to maximum */
- debt = gettotalbytes(g) - threshold;
- luaE_setdebt(g, debt);
-}
-
-
-/*
-** Enter first sweep phase.
-** The call to 'sweeplist' tries to make pointer 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.
-*/
-static void entersweep (lua_State *L) {
- global_State *g = G(L);
- g->gcstate = GCSswpallgc;
- lua_assert(g->sweepgc == NULL);
- g->sweepgc = sweeplist(L, &g->allgc, 1);
-}
-
-
-void luaC_freeallobjects (lua_State *L) {
- global_State *g = G(L);
- separatetobefnz(g, 1); /* separate all objects with finalizers */
- lua_assert(g->finobj == NULL);
- callallpendingfinalizers(L);
- lua_assert(g->tobefnz == NULL);
- g->currentwhite = WHITEBITS; /* this "white" makes all objects look dead */
- g->gckind = KGC_NORMAL;
- sweepwholelist(L, &g->finobj);
- sweepwholelist(L, &g->allgc);
- sweepwholelist(L, &g->fixedgc); /* collect fixed objects */
- lua_assert(g->strt.nuse == 0);
-}
-
-
-static l_mem atomic (lua_State *L) {
- global_State *g = G(L);
- l_mem work;
- GCObject *origweak, *origall;
- GCObject *grayagain = g->grayagain; /* save original list */
- lua_assert(g->ephemeron == NULL && g->weak == NULL);
- lua_assert(!iswhite(g->mainthread));
- g->gcstate = GCSinsideatomic;
- g->GCmemtrav = 0; /* start counting work */
- markobject(g, L); /* mark running thread */
- /* registry and global metatables may be changed by API */
- markvalue(g, &g->l_registry);
- markmt(g); /* mark global metatables */
- /* remark occasional upvalues of (maybe) dead threads */
- remarkupvals(g);
- propagateall(g); /* propagate changes */
- work = g->GCmemtrav; /* stop counting (do not recount 'grayagain') */
- g->gray = grayagain;
- propagateall(g); /* traverse 'grayagain' list */
- g->GCmemtrav = 0; /* restart counting */
- convergeephemerons(g);
- /* at this point, all strongly accessible objects are marked. */
- /* Clear values from weak tables, before checking finalizers */
- 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(g, 0); /* separate objects to be finalized */
- g->gcfinnum = 1; /* there may be objects to be finalized */
- markbeingfnz(g); /* mark objects that will be finalized */
- propagateall(g); /* remark, to propagate 'resurrection' */
- g->GCmemtrav = 0; /* restart counting */
- convergeephemerons(g);
- /* at this point, all resurrected objects are marked. */
- /* remove dead objects from weak 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, g->weak, origweak);
- clearvalues(g, g->allweak, origall);
- luaS_clearcache(g);
- g->currentwhite = cast_byte(otherwhite(g)); /* flip current white */
- work += g->GCmemtrav; /* complete counting */
- return work; /* estimate of memory marked by 'atomic' */
-}
-
-
-static lu_mem sweepstep (lua_State *L, global_State *g,
- int nextstate, GCObject **nextlist) {
- if (g->sweepgc) {
- l_mem olddebt = g->GCdebt;
- g->sweepgc = sweeplist(L, g->sweepgc, GCSWEEPMAX);
- g->GCestimate += g->GCdebt - olddebt; /* update estimate */
- if (g->sweepgc) /* is there still something to sweep? */
- return (GCSWEEPMAX * GCSWEEPCOST);
- }
- /* else enter next state */
- g->gcstate = nextstate;
- g->sweepgc = nextlist;
- return 0;
-}
-
-
-static lu_mem singlestep (lua_State *L) {
- global_State *g = G(L);
- switch (g->gcstate) {
- case GCSpause: {
- g->GCmemtrav = g->strt.size * sizeof(GCObject*);
- restartcollection(g);
- g->gcstate = GCSpropagate;
- return g->GCmemtrav;
- }
- case GCSpropagate: {
- g->GCmemtrav = 0;
- lua_assert(g->gray);
- propagatemark(g);
- if (g->gray == NULL) /* no more gray objects? */
- g->gcstate = GCSatomic; /* finish propagate phase */
- return g->GCmemtrav; /* memory traversed in this step */
- }
- case GCSatomic: {
- lu_mem work;
- propagateall(g); /* make sure gray list is empty */
- work = atomic(L); /* work is what was traversed by 'atomic' */
- entersweep(L);
- g->GCestimate = gettotalbytes(g); /* first estimate */;
- return work;
- }
- case GCSswpallgc: { /* sweep "regular" objects */
- return sweepstep(L, g, GCSswpfinobj, &g->finobj);
- }
- case GCSswpfinobj: { /* sweep objects with finalizers */
- return sweepstep(L, g, GCSswptobefnz, &g->tobefnz);
- }
- case GCSswptobefnz: { /* sweep objects to be finalized */
- return sweepstep(L, g, GCSswpend, NULL);
- }
- case GCSswpend: { /* finish sweeps */
- makewhite(g, g->mainthread); /* sweep main thread */
- checkSizes(L, g);
- g->gcstate = GCScallfin;
- return 0;
- }
- case GCScallfin: { /* call remaining finalizers */
- if (g->tobefnz && g->gckind != KGC_EMERGENCY) {
- int n = runafewfinalizers(L);
- return (n * GCFINALIZECOST);
- }
- else { /* emergency mode or no more finalizers */
- g->gcstate = GCSpause; /* finish collection */
- return 0;
- }
- }
- default: lua_assert(0); return 0;
- }
-}
-
-
-/*
-** 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);
- while (!testbit(statesmask, g->gcstate))
- singlestep(L);
-}
-
-
-/*
-** get GC debt and convert it from Kb to 'work units' (avoid zero debt
-** and overflows)
-*/
-static l_mem getdebt (global_State *g) {
- l_mem debt = g->GCdebt;
- int stepmul = g->gcstepmul;
- if (debt <= 0) return 0; /* minimal debt */
- else {
- debt = (debt / STEPMULADJ) + 1;
- debt = (debt < MAX_LMEM / stepmul) ? debt * stepmul : MAX_LMEM;
- return debt;
- }
-}
-
-/*
-** performs a basic GC step when collector is running
-*/
-void luaC_step (lua_State *L) {
- global_State *g = G(L);
- l_mem debt = getdebt(g); /* GC deficit (be paid now) */
- if (!g->gcrunning) { /* not running? */
- luaE_setdebt(g, -GCSTEPSIZE * 10); /* avoid being called too often */
- return;
- }
- do { /* repeat until pause or enough "credit" (negative debt) */
- lu_mem work = singlestep(L); /* perform one single step */
- debt -= work;
- } while (debt > -GCSTEPSIZE && g->gcstate != GCSpause);
- if (g->gcstate == GCSpause)
- setpause(g); /* pause until next cycle */
- else {
- debt = (debt / g->gcstepmul) * STEPMULADJ; /* convert 'work units' to Kb */
- luaE_setdebt(g, debt);
- runafewfinalizers(L);
- }
-}
-
-
-/*
-** Performs a full GC cycle; if 'isemergency', set a flag to avoid
-** some operations which could change the interpreter state in some
-** unexpected ways (running finalizers and shrinking some structures).
-** Before running the collection, check 'keepinvariant'; if it is true,
-** there may be some objects marked as black, so the collector has
-** to sweep all objects to turn them back to white (as white has not
-** changed, nothing will be collected).
-*/
-void luaC_fullgc (lua_State *L, int isemergency) {
- global_State *g = G(L);
- lua_assert(g->gckind == KGC_NORMAL);
- if (isemergency) g->gckind = KGC_EMERGENCY; /* set flag */
- if (keepinvariant(g)) { /* black objects? */
- entersweep(L); /* sweep everything to turn them back to white */
- }
- /* finish any pending sweep phase to start a new cycle */
- luaC_runtilstate(L, bitmask(GCSpause));
- luaC_runtilstate(L, ~bitmask(GCSpause)); /* start new collection */
- luaC_runtilstate(L, bitmask(GCScallfin)); /* run up to finalizers */
- /* estimate must be correct after a full GC cycle */
- lua_assert(g->GCestimate == gettotalbytes(g));
- luaC_runtilstate(L, bitmask(GCSpause)); /* finish collection */
- g->gckind = KGC_NORMAL;
- setpause(g);
-}
-
-/* }====================================================== */
-
-
projects / ardour.git / blobdiff