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new way to GC stacks: the entire stack must be correct all the times; 

the 'dead' part of a stack (after the top) must have only nil's, so
that 'top' may go up without cleaning the stack.
This commit is contained in:
Roberto Ierusalimschy 2009-04-28 16:04:36 -03:00
parent 58c3aa8b5f
commit e091a254df
4 changed files with 63 additions and 47 deletions
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26
ldo.c
View File

@ -1,5 +1,5 @@
/*
** $Id: ldo.c,v 2.61 2009/04/17 22:00:01 roberto Exp roberto $
** $Id: ldo.c,v 2.62 2009/04/26 21:55:35 roberto Exp roberto $
** Stack and Call structure of Lua
** See Copyright Notice in lua.h
*/
@ -131,9 +131,12 @@ static void correctstack (lua_State *L, TValue *oldstack) {
void luaD_reallocstack (lua_State *L, int newsize) {
TValue *oldstack = L->stack;
int lim = L->stacksize;
int realsize = newsize + 1 + EXTRA_STACK;
lua_assert(L->stack_last - L->stack == L->stacksize - EXTRA_STACK - 1);
luaM_reallocvector(L, L->stack, L->stacksize, realsize, TValue);
for (; lim < realsize; lim++)
setnilvalue(L->stack + lim); /* erase new segment */
L->stacksize = realsize;
L->stack_last = L->stack+newsize;
correctstack(L, oldstack);
@ -182,14 +185,13 @@ static StkId adjust_varargs (lua_State *L, Proto *p, int actual) {
int i;
int nfixargs = p->numparams;
StkId base, fixed;
for (; actual < nfixargs; ++actual)
setnilvalue(L->top++);
lua_assert(actual >= nfixargs);
/* move fixed parameters to final position */
fixed = L->top - actual; /* first fixed argument */
base = L->top; /* final position of first argument */
for (i=0; i<nfixargs; i++) {
setobjs2s(L, L->top++, fixed+i);
setnilvalue(fixed+i);
setobjs2s(L, L->top++, fixed + i);
setnilvalue(fixed + i);
}
return base;
}
@ -227,17 +229,19 @@ int luaD_precall (lua_State *L, StkId func, int nresults) {
L->ci->nresults = nresults;
if (!cl->isC) { /* Lua function? prepare its call */
CallInfo *ci;
StkId st, base;
int nparams, nargs;
StkId base;
Proto *p = cl->p;
luaD_checkstack(L, p->maxstacksize);
func = restorestack(L, funcr);
nargs = cast_int(L->top - func) - 1; /* number of real arguments */
nparams = p->numparams; /* number of expected parameters */
for (; nargs < nparams; nargs++)
setnilvalue(L->top++); /* complete missing arguments */
if (!p->is_vararg) /* no varargs? */
base = func + 1;
else { /* vararg function */
int nargs = cast_int(L->top - func) - 1;
else /* vararg function */
base = adjust_varargs(L, p, nargs);
func = restorestack(L, funcr); /* previous call may change the stack */
}
ci = next_ci(L); /* now 'enter' new function */
ci->func = func;
L->base = ci->base = base;
@ -246,8 +250,6 @@ int luaD_precall (lua_State *L, StkId func, int nresults) {
ci->u.l.savedpc = p->code; /* starting point */
ci->u.l.tailcalls = 0;
ci->callstatus = CIST_LUA;
for (st = L->top; st < ci->top; st++)
setnilvalue(st);
L->top = ci->top;
if (L->hookmask & LUA_MASKCALL) {
ci->u.l.savedpc++; /* hooks assume 'pc' is already incremented */

70
lgc.c
View File

@ -1,5 +1,5 @@
/*
** $Id: lgc.c,v 2.49 2009/03/10 17:14:37 roberto Exp roberto $
** $Id: lgc.c,v 2.50 2009/04/17 14:28:06 roberto Exp roberto $
** Garbage Collector
** See Copyright Notice in lua.h
*/
@ -379,34 +379,17 @@ static void traverseclosure (global_State *g, Closure *cl) {
}
static void checkstacksize (lua_State *L, StkId max) {
/* should not change the stack during an emergency gc cycle */
if (G(L)->gckind == KGC_EMERGENCY)
return; /* do not touch the stack */
else {
int s_used = cast_int(max - L->stack) + 1; /* part of stack in use */
if (2*s_used < (L->stacksize - EXTRA_STACK))
luaD_reallocstack(L, 2*s_used);
}
}
static void traversestack (global_State *g, lua_State *L) {
StkId o, lim;
CallInfo *ci;
StkId o;
if (L->stack == NULL)
return; /* stack not completely built yet */
markvalue(g, gt(L));
lim = L->top;
for (ci = L->ci; ci != NULL; ci = ci->previous) {
lua_assert(ci->top <= L->stack_last);
if (lim < ci->top) lim = ci->top;
}
markvalue(g, gt(L)); /* mark global table */
for (o = L->stack; o < L->top; o++)
markvalue(g, o);
for (; o <= lim; o++)
setnilvalue(o);
checkstacksize(L, lim);
if (g->gcstate == GCSatomic) { /* final traversal? */
for (; o <= L->stack_last; o++) /* clear not-marked stack slice */
setnilvalue(o);
}
}
@ -542,7 +525,35 @@ static void freeobj (lua_State *L, GCObject *o) {
}
static int stackinuse (lua_State *L) {
CallInfo *ci;
StkId lim = L->top;
for (ci = L->ci; ci != NULL; ci = ci->previous) {
lua_assert(ci->top <= L->stack_last);
if (lim < ci->top) lim = ci->top;
}
return cast_int(lim - L->stack) + 1; /* part of stack in use */
}
#define sweepwholelist(L,p) sweeplist(L,p,MAX_LUMEM)
static GCObject **sweeplist (lua_State *L, GCObject **p, lu_mem count);
static void sweepthread (lua_State *L, lua_State *L1, int alive) {
if (L1->stack == NULL) return; /* stack not completely built yet */
sweepwholelist(L, &L1->openupval); /* sweep open upvalues */
if (L1->nci < LUAI_MAXCALLS) /* not handling stack overflow? */
luaE_freeCI(L1); /* free extra CallInfo slots */
/* should not change the stack during an emergency gc cycle */
if (alive && G(L)->gckind != KGC_EMERGENCY) {
int goodsize = 5 * stackinuse(L1) / 4 + LUA_MINSTACK;
if ((L1->stacksize - EXTRA_STACK) > goodsize)
luaD_reallocstack(L1, goodsize);
else
condhardstacktests(luaD_reallocstack(L, L1->stacksize - EXTRA_STACK - 1));
}
}
static GCObject **sweeplist (lua_State *L, GCObject **p, lu_mem count) {
@ -550,12 +561,10 @@ static GCObject **sweeplist (lua_State *L, GCObject **p, lu_mem count) {
global_State *g = G(L);
int deadmask = otherwhite(g);
while ((curr = *p) != NULL && count-- > 0) {
if (ttisthread(gch(curr))) {
lua_State *L1 = gco2th(curr);
sweepwholelist(L, &L1->openupval); /* sweep open upvalues */
luaE_freeCI(L1); /* free extra CallInfo slots */
}
if ((gch(curr)->marked ^ WHITEBITS) & deadmask) { /* not dead? */
int alive = (gch(curr)->marked ^ WHITEBITS) & deadmask;
if (ttisthread(gch(curr)))
sweepthread(L, gco2th(curr), alive);
if (alive) {
lua_assert(!isdead(g, curr) || testbit(gch(curr)->marked, FIXEDBIT));
makewhite(g, curr); /* make it white (for next cycle) */
p = &gch(curr)->next;
@ -704,6 +713,7 @@ 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 */
g->gcstate = GCSatomic;
remarkupvals(g);
/* traverse objects cautch by write barrier and by 'remarkupvals' */
propagateall(g);

9
lgc.h
View File

@ -1,5 +1,5 @@
/*
** $Id: lgc.h,v 2.18 2008/02/19 18:55:09 roberto Exp roberto $
** $Id: lgc.h,v 2.19 2008/06/26 19:42:45 roberto Exp roberto $
** Garbage Collector
** See Copyright Notice in lua.h
*/
@ -16,9 +16,10 @@
*/
#define GCSpause 0
#define GCSpropagate 1
#define GCSsweepstring 2
#define GCSsweep 3
#define GCSfinalize 4
#define GCSatomic 2
#define GCSsweepstring 3
#define GCSsweep 4
#define GCSfinalize 5
#define issweep(g) (GCSsweepstring <= (g)->gcstate && (g)->gcstate <= GCSsweep)

5
lstate.c
View File

@ -1,5 +1,5 @@
/*
** $Id: lstate.c,v 2.52 2009/04/17 14:40:13 roberto Exp roberto $
** $Id: lstate.c,v 2.53 2009/04/17 22:00:01 roberto Exp roberto $
** Global State
** See Copyright Notice in lua.h
*/
@ -75,9 +75,12 @@ void luaE_freeCI (lua_State *L) {
static void stack_init (lua_State *L1, lua_State *L) {
int i;
/* initialize stack array */
L1->stack = luaM_newvector(L, BASIC_STACK_SIZE + EXTRA_STACK, TValue);
L1->stacksize = BASIC_STACK_SIZE + EXTRA_STACK;
for (i = 0; i < BASIC_STACK_SIZE + EXTRA_STACK; i++)
setnilvalue(L1->stack + i); /* erase new stack */
L1->top = L1->stack;
L1->stack_last = L1->stack+(L1->stacksize - EXTRA_STACK)-1;
/* initialize first ci */