mirror of
https://github.com/lua/lua
synced 2024-12-12 22:07:13 +03:00
4a24883674
single step individually
1176 lines
35 KiB
C
1176 lines
35 KiB
C
/*
|
|
** $Id: lgc.c,v 2.181 2014/04/02 16:44:42 roberto Exp roberto $
|
|
** Garbage Collector
|
|
** See Copyright Notice in lua.h
|
|
*/
|
|
|
|
#include <string.h>
|
|
|
|
#define lgc_c
|
|
#define LUA_CORE
|
|
|
|
#include "lua.h"
|
|
|
|
#include "ldebug.h"
|
|
#include "ldo.h"
|
|
#include "lfunc.h"
|
|
#include "lgc.h"
|
|
#include "lmem.h"
|
|
#include "lobject.h"
|
|
#include "lstate.h"
|
|
#include "lstring.h"
|
|
#include "ltable.h"
|
|
#include "ltm.h"
|
|
|
|
|
|
/*
|
|
** 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) \
|
|
(gch(x)->marked = cast_byte((gch(x)->marked & maskcolors) | luaC_white(g)))
|
|
|
|
#define white2gray(x) resetbits(gch(x)->marked, WHITEBITS)
|
|
#define black2gray(x) resetbit(gch(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 ((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)))
|
|
|
|
|
|
/*
|
|
** 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 (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 (global_State *g, const TValue *o) {
|
|
if (!iscollectable(o)) return 0;
|
|
else if (ttisstring(o)) {
|
|
markobject(g, 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(g->gcstate != GCSpause);
|
|
lua_assert(gch(o)->tt != LUA_TTABLE); /* tables use a back barrier */
|
|
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 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->gch.next; /* remove object from 'allgc' list */
|
|
o->gch.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));
|
|
gch(o)->marked = luaC_white(g);
|
|
gch(o)->tt = tt;
|
|
gch(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 (gch(o)->tt) {
|
|
case LUA_TSHRSTR:
|
|
case LUA_TLNGSTR: {
|
|
gray2black(o);
|
|
g->GCmemtrav += sizestring(gco2ts(o));
|
|
break;
|
|
}
|
|
case LUA_TUSERDATA: {
|
|
TValue uvalue;
|
|
markobject(g, gco2u(o)->metatable); /* mark its metatable */
|
|
gray2black(o);
|
|
g->GCmemtrav += sizeudata(gco2u(o));
|
|
getuservalue(g->mainthread, rawgco2u(o), &uvalue);
|
|
if (valiswhite(&uvalue)) { /* markvalue(g, &uvalue); */
|
|
o = gcvalue(&uvalue);
|
|
goto reentry;
|
|
}
|
|
break;
|
|
}
|
|
case LUA_TLCL: {
|
|
gco2lcl(o)->gclist = g->gray;
|
|
g->gray = o;
|
|
break;
|
|
}
|
|
case LUA_TCCL: {
|
|
gco2ccl(o)->gclist = g->gray;
|
|
g->gray = o;
|
|
break;
|
|
}
|
|
case LUA_TTABLE: {
|
|
linktable(gco2t(o), &g->gray);
|
|
break;
|
|
}
|
|
case LUA_TTHREAD: {
|
|
gco2th(o)->gclist = g->gray;
|
|
g->gray = o;
|
|
break;
|
|
}
|
|
case LUA_TPROTO: {
|
|
gco2p(o)->gclist = g->gray;
|
|
g->gray = o;
|
|
break;
|
|
}
|
|
default: lua_assert(0); break;
|
|
}
|
|
}
|
|
|
|
|
|
/*
|
|
** 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)
|
|
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(obj2gco(thread))); /* threads are never black */
|
|
if (isgray(obj2gco(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
|
|
** =======================================================
|
|
*/
|
|
|
|
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)));
|
|
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 (hasclears)
|
|
linktable(h, &g->weak); /* has to be cleared later */
|
|
else /* no white values */
|
|
linktable(h, &g->grayagain); /* no need to clean */
|
|
}
|
|
|
|
|
|
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;
|
|
/* 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]));
|
|
}
|
|
}
|
|
/* 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? */
|
|
prop = 1; /* must propagate again */
|
|
}
|
|
else if (valiswhite(gval(n))) { /* value not marked yet? */
|
|
marked = 1;
|
|
reallymarkobject(g, gcvalue(gval(n))); /* mark it now */
|
|
}
|
|
}
|
|
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 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? */
|
|
((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 */
|
|
}
|
|
else /* not weak */
|
|
traversestrongtable(g, h);
|
|
return sizeof(Table) + sizeof(TValue) * h->sizearray +
|
|
sizeof(Node) * cast(size_t, sizenode(h));
|
|
}
|
|
|
|
|
|
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 */
|
|
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 */
|
|
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 */
|
|
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 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;
|
|
markobject(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 traversestack (global_State *g, lua_State *th) {
|
|
int n = 0;
|
|
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 {
|
|
CallInfo *ci;
|
|
for (ci = &th->base_ci; ci != th->ci; ci = ci->next)
|
|
n++; /* count call infos to compute size */
|
|
/* should not change the stack during an emergency gc cycle */
|
|
if (g->gckind != KGC_EMERGENCY)
|
|
luaD_shrinkstack(th);
|
|
}
|
|
return sizeof(lua_State) + sizeof(TValue) * th->stacksize +
|
|
sizeof(CallInfo) * n;
|
|
}
|
|
|
|
|
|
/*
|
|
** 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 (gch(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 */
|
|
th->gclist = g->grayagain;
|
|
g->grayagain = o; /* insert into 'grayagain' list */
|
|
black2gray(o);
|
|
size = traversestack(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 propagatelist (global_State *g, GCObject *l) {
|
|
lua_assert(g->gray == NULL); /* no grays left */
|
|
g->gray = l;
|
|
propagateall(g); /* traverse all elements from 'l' */
|
|
}
|
|
|
|
/*
|
|
** 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 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 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);
|
|
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 (gch(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, rawgco2ts(o)); /* remove it from hash table */
|
|
/* go through */
|
|
case LUA_TLNGSTR: {
|
|
luaM_freemem(L, o, sizestring(gco2ts(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 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; change all non-dead objects back
|
|
** to white, preparing for next collection cycle.
|
|
** When object is a thread, sweep its list of open upvalues too.
|
|
*/
|
|
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 = gch(curr)->marked;
|
|
if (isdeadm(ow, marked)) { /* is 'curr' dead? */
|
|
*p = gch(curr)->next; /* remove 'curr' from list */
|
|
freeobj(L, curr); /* erase 'curr' */
|
|
}
|
|
else { /* update marks */
|
|
gch(curr)->marked = cast_byte((marked & maskcolors) | white);
|
|
p = &gch(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, int *n) {
|
|
GCObject **old = p;
|
|
int i = 0;
|
|
do {
|
|
i++;
|
|
p = sweeplist(L, p, 1);
|
|
} while (p == old);
|
|
if (n) *n += i;
|
|
return p;
|
|
}
|
|
|
|
/* }====================================================== */
|
|
|
|
|
|
/*
|
|
** {======================================================
|
|
** Finalization
|
|
** =======================================================
|
|
*/
|
|
|
|
/*
|
|
** If possible, free concatenation buffer and shrink string table
|
|
*/
|
|
static void checkSizes (lua_State *L, global_State *g) {
|
|
if (g->gckind != KGC_EMERGENCY) {
|
|
l_mem olddebt = g->GCdebt;
|
|
luaZ_freebuffer(L, &g->buff); /* free concatenation buffer */
|
|
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 = 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, 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_call(L, L->top - 2, 0, 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 all pending finalizers
|
|
*/
|
|
static void callallpendingfinalizers (lua_State *L, int propagateerrors) {
|
|
global_State *g = G(L);
|
|
while (g->tobefnz)
|
|
GCTM(L, propagateerrors);
|
|
}
|
|
|
|
|
|
/*
|
|
** find last 'next' field in list 'p' list (to add elements in its end)
|
|
*/
|
|
static GCObject **findlast (GCObject **p) {
|
|
while (*p != NULL)
|
|
p = &gch(*p)->next;
|
|
return p;
|
|
}
|
|
|
|
|
|
/*
|
|
** move all unreachable objects (or 'all' objects) that need
|
|
** finalization from list 'p' 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 = &gch(curr)->next; /* don't bother with it */
|
|
else {
|
|
*p = gch(curr)->next; /* remove 'curr' from "fin" list */
|
|
gch(curr)->next = *lastnext; /* link at the end of 'tobefnz' list */
|
|
*lastnext = curr;
|
|
lastnext = &gch(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->gch.next) /* shoud not remove 'sweepgc' object */
|
|
g->sweepgc = sweeptolive(L, g->sweepgc, NULL); /* change 'sweepgc' */
|
|
}
|
|
/* search for pointer pointing to 'o' */
|
|
for (p = &g->allgc; *p != o; p = &gch(*p)->next) { /* empty */ }
|
|
*p = o->gch.next; /* remove 'o' from 'allgc' list */
|
|
o->gch.next = g->finobj; /* link it in "fin" list */
|
|
g->finobj = o;
|
|
l_setbit(o->gch.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
|
|
*/
|
|
static void setpause (global_State *g) {
|
|
l_mem threshold, debt;
|
|
l_mem estimate = g->GCestimate / PAUSEADJ; /* adjust 'estimate' */
|
|
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 'sweeptolive' makes 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.
|
|
** Returns how many objects it swept.
|
|
*/
|
|
static int entersweep (lua_State *L) {
|
|
global_State *g = G(L);
|
|
int n = 0;
|
|
g->gcstate = GCSswpallgc;
|
|
lua_assert(g->sweepgc == NULL);
|
|
g->sweepgc = sweeptolive(L, &g->allgc, &n);
|
|
return n;
|
|
}
|
|
|
|
|
|
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, 0);
|
|
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;
|
|
g->GCmemtrav = 0; /* start counting work */
|
|
lua_assert(!iswhite(obj2gco(g->mainthread)));
|
|
g->gcstate = GCSinsideatomic;
|
|
markobject(g, L); /* mark running thread */
|
|
/* 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);
|
|
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);
|
|
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);
|
|
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;
|
|
int sw;
|
|
propagateall(g); /* make sure gray list is empty */
|
|
work = atomic(L); /* work is what was traversed by 'atomic' */
|
|
sw = entersweep(L);
|
|
g->GCestimate = gettotalbytes(g); /* first estimate */;
|
|
return work + sw * GCSWEEPCOST;
|
|
}
|
|
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, obj2gco(g->mainthread)); /* sweep main thread */
|
|
checkSizes(L, g);
|
|
g->gcstate = GCScallfin;
|
|
return 0;
|
|
}
|
|
case GCScallfin: { /* state to finish calling finalizers */
|
|
/* do nothing here; this state is handled by 'luaC_step' */
|
|
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);
|
|
}
|
|
|
|
|
|
/*
|
|
** run 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;
|
|
}
|
|
|
|
|
|
/*
|
|
** 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;
|
|
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);
|
|
if (!g->gcrunning) { /* not running? */
|
|
luaE_setdebt(g, -GCSTEPSIZE * 10); /* avoid being called too often */
|
|
return;
|
|
}
|
|
do {
|
|
if (g->gcstate == GCScallfin && g->tobefnz) {
|
|
unsigned int n = runafewfinalizers(L);
|
|
debt -= (n * GCFINALIZECOST);
|
|
}
|
|
else { /* perform one single step */
|
|
lu_mem work = singlestep(L);
|
|
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", does not call
|
|
** finalizers (which could change stack positions)
|
|
*/
|
|
void luaC_fullgc (lua_State *L, int isemergency) {
|
|
global_State *g = G(L);
|
|
lua_assert(g->gckind == KGC_NORMAL);
|
|
if (isemergency) /* do not run finalizers during emergency GC */
|
|
g->gckind = KGC_EMERGENCY;
|
|
else
|
|
callallpendingfinalizers(L, 1);
|
|
if (keepinvariant(g)) { /* 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) */
|
|
entersweep(L);
|
|
}
|
|
/* 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(GCSpause)); /* run entire collection */
|
|
/* estimate must be correct after full GC cycles */
|
|
lua_assert(g->GCestimate == gettotalbytes(g));
|
|
g->gckind = KGC_NORMAL;
|
|
setpause(g);
|
|
if (!isemergency) /* do not run finalizers during emergency GC */
|
|
callallpendingfinalizers(L, 1);
|
|
}
|
|
|
|
/* }====================================================== */
|
|
|
|
|