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first implementation of generational GC

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This commit is contained in:
Roberto Ierusalimschy 2004-08-24 17:12:06 -03:00
parent 4b12eff801
commit 32d4f304db
7 changed files with 162 additions and 159 deletions
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257
lgc.c
View file

@ -1,5 +1,5 @@
/*
** $Id: lgc.c,v 2.7 2004/04/30 20:13:38 roberto Exp roberto $
** $Id: lgc.c,v 2.8 2004/08/10 19:17:23 roberto Exp roberto $
** Garbage Collector
** See Copyright Notice in lua.h
*/
@ -25,10 +25,11 @@
#define GCSTEPSIZE (40*sizeof(TValue))
#define STEPMUL 2
#define GCFREECOST (sizeof(TValue)/10)
#define GCSWEEPCOST (sizeof(TValue)/20)
#define GCSWEEPMAX 40
#define GCSWEEPCOST 1
#define GCFINALIZECOST (10*sizeof(TValue))
#define WAITNEXTCYCLE (10 * GCSTEPSIZE)
#define WAITNEXTCYCLE (40 * GCSTEPSIZE)
#define WAITNEXTCYCLEGN (200 * GCSTEPSIZE)
#define FIXEDMASK bitmask(FIXEDBIT)
@ -269,60 +270,61 @@ static void traversestack (global_State *g, lua_State *l) {
/*
** traverse a given `quantity' of gray objects,
** turning them to black. Returns extra `quantity' traversed.
** traverse one gray object, turning it to black.
** Returns `quantity' traversed.
*/
static l_mem propagatemarks (global_State *g, l_mem lim) {
GCObject *o;
while ((o = g->gray) != NULL) {
lua_assert(isgray(o));
gray2black(o);
switch (o->gch.tt) {
case LUA_TTABLE: {
Table *h = gco2h(o);
g->gray = h->gclist;
if (traversetable(g, h)) /* table is weak? */
black2gray(o); /* keep it gray */
lim -= sizeof(Table) + sizeof(TValue) * h->sizearray +
sizeof(Node) * sizenode(h);
break;
}
case LUA_TFUNCTION: {
Closure *cl = gco2cl(o);
g->gray = cl->c.gclist;
traverseclosure(g, cl);
lim -= (cl->c.isC) ? sizeCclosure(cl->c.nupvalues) :
sizeLclosure(cl->l.nupvalues);
break;
}
case LUA_TTHREAD: {
lua_State *th = gco2th(o);
g->gray = th->gclist;
th->gclist = g->grayagain;
g->grayagain = o;
black2gray(o);
traversestack(g, th);
lim -= sizeof(lua_State) + sizeof(TValue) * th->stacksize +
sizeof(CallInfo) * th->size_ci;
break;
}
case LUA_TPROTO: {
Proto *p = gco2p(o);
g->gray = p->gclist;
traverseproto(g, p);
lim -= 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;
break;
}
default: lua_assert(0);
static l_mem propagatemark (global_State *g) {
GCObject *o = g->gray;
lua_assert(isgray(o));
gray2black(o);
switch (o->gch.tt) {
case LUA_TTABLE: {
Table *h = gco2h(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);
break;
}
if (lim <= 0) return lim;
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);
break;
}
case LUA_TTHREAD: {
lua_State *th = gco2th(o);
g->gray = th->gclist;
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;
break;
}
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;
break;
}
default: lua_assert(0); return 0;
}
return lim;
}
static void propagateall (global_State *g) {
while (g->gray) propagatemark(g);
}
@ -384,6 +386,7 @@ static void freeobj (lua_State *L, GCObject *o) {
break;
}
case LUA_TSTRING: {
G(L)->strt.nuse--;
luaM_free(L, o, sizestring(gco2ts(o)->len));
break;
}
@ -396,59 +399,50 @@ static void freeobj (lua_State *L, GCObject *o) {
}
static l_mem sweepwholelist (lua_State *L, GCObject **p, int keepfixed,
lu_int32 *count);
#define sweepwholelist(L,p) sweeplist(L,p,LUA_MAXINT32)
static GCObject **sweeplist (lua_State *L, GCObject **p, int keepfixed,
l_mem *plim, lu_int32 *count) {
static GCObject **sweeplist (lua_State *L, GCObject **p, lu_int32 count) {
GCObject *curr;
global_State *g = G(L);
l_mem lim = *plim;
int deadmask = otherwhite(g);
if (keepfixed) deadmask |= FIXEDMASK;
int whitebit = otherwhite(g);
int deadmask = whitebit | FIXEDMASK;
while ((curr = *p) != NULL) {
if (((curr->gch.marked ^ FIXEDMASK) & deadmask) != deadmask) {
makewhite(g, curr);
if ((curr->gch.marked ^ whitebit) & deadmask) {
lua_assert(!isdead(g, curr) || testbit(curr->gch.marked, FIXEDBIT));
if (!G(L)->gcgenerational || isdead(g, curr))
makewhite(g, curr);
if (curr->gch.tt == LUA_TTHREAD)
lim -= sweepwholelist(L, &gco2th(curr)->openupval, keepfixed, count);
sweepwholelist(L, &gco2th(curr)->openupval);
p = &curr->gch.next;
lim -= GCSWEEPCOST;
}
else {
lua_assert(iswhite(curr));
lua_assert(isdead(g, curr));
*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);
lim -= GCFREECOST;
if (count) (*count)--;
}
if (lim <= 0) break;
if (count-- == 0) break;
}
*plim = lim;
return p;
}
static l_mem sweepwholelist (lua_State *L, GCObject **p, int keepfixed,
lu_int32 *count) {
l_mem lim = MAXLMEM;
/* empty lists are quite common here, so avoid useless calls */
if (*p) sweeplist(L, p, keepfixed, &lim, count);
return MAXLMEM - lim;
static void sweepstrings (lua_State *L) {
global_State *g = G(L);
sweepwholelist(L, &G(L)->strt.hash[g->sweepstrgc++]);
}
static l_mem sweepstrings (lua_State *L, int keepfixed, l_mem lim) {
int i;
global_State *g = G(L);
for (i = g->sweepstrgc; i < g->strt.size; i++) { /* for each list */
lim -= sweepwholelist(L, &G(L)->strt.hash[i], keepfixed, &g->strt.nuse);
if (lim <= 0) break;
static void freelist (lua_State *L, GCObject **p) {
while (*p) {
GCObject *curr = *p;
*p = (*p)->gch.next;
if (curr != obj2gco(L))
freeobj(L, curr);
}
g->sweepstrgc = i+1;
return lim;
}
@ -497,19 +491,12 @@ void luaC_callGCTM (lua_State *L) {
}
void luaC_sweepall (lua_State *L) {
void luaC_freeall (lua_State *L) {
global_State *g = G(L);
l_mem dummy = MAXLMEM;
/* finish (occasional) current sweep */
sweepstrings(L, 0, MAXLMEM);
sweeplist(L, &g->rootgc, 0, &dummy, NULL);
/* do a whole new sweep */
markobject(g, g->mainthread); /* cannot collect main thread */
g->currentwhite = otherwhite(g);
g->sweepgc = &g->rootgc;
g->sweepstrgc = 0;
sweepstrings(L, 0, MAXLMEM);
sweeplist(L, &g->rootgc, 0, &dummy, NULL);
int i;
freelist(L, &g->rootgc);
for (i = 0; i < g->strt.size; i++) /* free all string lists */
freelist(L, &G(L)->strt.hash[i]);
}
@ -553,64 +540,68 @@ static void atomic (lua_State *L) {
g->weak = NULL;
lua_assert(!iswhite(obj2gco(g->mainthread)));
markobject(g, L); /* mark running thread */
propagatemarks(g, MAXLMEM);
propagateall(g);
/* remark gray again */
g->gray = g->grayagain;
g->grayagain = NULL;
propagatemarks(g, MAXLMEM);
propagateall(g);
luaC_separateudata(L, 0); /* separate userdata to be preserved */
marktmu(g); /* mark `preserved' userdata */
propagatemarks(g, MAXLMEM); /* remark, to propagate `preserveness' */
propagateall(g); /* remark, to propagate `preserveness' */
cleartable(g->weak); /* remove collected objects from weak tables */
/* flip current white */
g->currentwhite = otherwhite(g);
g->sweepstrgc = 0;
g->sweepgc = &g->rootgc;
g->gcstate = GCSsweepstring;
if (g->gcgenerational++ > 20) g->gcgenerational = 0;
}
static l_mem singlestep (lua_State *L, l_mem lim) {
static l_mem singlestep (lua_State *L) {
global_State *g = G(L);
/*lua_checkmemory(L);*/
switch (g->gcstate) {
case GCSpropagate: {
if (g->gray)
lim = propagatemarks(g, lim);
return propagatemark(g);
else { /* no more `gray' objects */
atomic(L); /* finish mark phase */
lim = 0;
return 0;
}
break;
}
case GCSsweepstring: {
lim = sweepstrings(L, 1, lim);
if (g->sweepstrgc >= g->strt.size) { /* nothing more to sweep? */
g->sweepstrgc = 0;
sweepstrings(L);
if (g->sweepstrgc >= g->strt.size) /* nothing more to sweep? */
g->gcstate = GCSsweep; /* end sweep-string phase */
}
break;
return GCSWEEPCOST;
}
case GCSsweep: {
g->sweepgc = sweeplist(L, g->sweepgc, 1, &lim, NULL);
g->sweepgc = sweeplist(L, g->sweepgc, GCSWEEPMAX);
if (*g->sweepgc == NULL) { /* nothing more to sweep? */
checkSizes(L);
g->sweepgc = &g->rootgc;
g->gcstate = GCSfinalize; /* end sweep phase */
}
break;
return GCSWEEPCOST;
}
case GCSfinalize: {
if (g->tmudata) {
GCTM(L);
lim -= GCFINALIZECOST;
return GCFINALIZECOST;
}
else { /* no more `udata' to finalize */
markroot(L); /* may restart collection */
lim = 0;
if (g->gcgenerational) {
atomic(L);
return WAITNEXTCYCLEGN;
}
else {
markroot(L); /* may restart collection */
return WAITNEXTCYCLE;
}
}
break;
}
default: lua_assert(0);
default: lua_assert(0); return 0;
}
return lim;
}
@ -618,11 +609,7 @@ void luaC_step (lua_State *L) {
global_State *g = G(L);
l_mem lim = (g->nblocks - (g->GCthreshold - GCSTEPSIZE)) * STEPMUL;
do {
lim = singlestep(L, lim);
if (g->gcstate == GCSfinalize && g->tmudata == NULL) {
lim = -WAITNEXTCYCLE;
break; /* do not start new collection */
}
lim -= singlestep(L);
} while (lim > 0);
g->GCthreshold = g->nblocks + GCSTEPSIZE - lim/STEPMUL;
lua_assert((long)g->nblocks + (long)GCSTEPSIZE >= lim/STEPMUL);
@ -631,12 +618,26 @@ void luaC_step (lua_State *L) {
void luaC_fullgc (lua_State *L) {
global_State *g = G(L);
if (g->gcstate == GCSpropagate || g->gcgenerational) {
g->gcgenerational = 0;
/* 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;
}
/* finish any pending sweep phase */
while (g->gcstate != GCSfinalize) {
singlestep(L, MAXLMEM);
singlestep(L);
}
markroot(L);
lua_assert(!g->gcgenerational);
while (g->gcstate != GCSfinalize) {
singlestep(L, MAXLMEM);
singlestep(L);
g->gcgenerational = 0; /* keep it in this mode */
}
g->GCthreshold = g->nblocks + GCSTEPSIZE;
luaC_callGCTM(L); /* call finalizers */
@ -646,7 +647,7 @@ void luaC_fullgc (lua_State *L) {
void luaC_barrierf (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 != GCSfinalize);
lua_assert(g->gcgenerational || g->gcstate != GCSfinalize);
if (g->gcstate != GCSpropagate) /* sweeping phases? */
black2gray(o); /* just mark as gray to avoid other barriers */
else /* breaking invariant! */
@ -657,7 +658,7 @@ void luaC_barrierf (lua_State *L, GCObject *o, GCObject *v) {
void luaC_barrierback (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 != GCSfinalize);
lua_assert(g->gcgenerational || g->gcstate != GCSfinalize);
black2gray(o); /* make table gray (again) */
gco2h(o)->gclist = g->grayagain;
g->grayagain = o;
@ -679,7 +680,7 @@ void luaC_linkupval (lua_State *L, UpVal *uv) {
o->gch.next = g->rootgc; /* link upvalue into `rootgc' list */
g->rootgc = o;
if (isgray(o)) {
if (g->gcstate == GCSpropagate) {
if (g->gcstate == GCSpropagate || g->gcgenerational) {
gray2black(o); /* closed upvalues need barrier */
luaC_barrier(L, uv, uv->v);
}

17
lgc.h
View file

@ -1,5 +1,5 @@
/*
** $Id: lgc.h,v 2.5 2004/03/15 21:04:33 roberto Exp roberto $
** $Id: lgc.h,v 2.6 2004/08/10 19:17:23 roberto Exp roberto $
** Garbage Collector
** See Copyright Notice in lua.h
*/
@ -39,12 +39,13 @@
/*
** Layout for bit use in `marked' field:
** bit 0 - object is gray
** bit 1 - object is black
** bit 2 - For userdata: is finalized;
for tables: has weak keys
** bit 3 - for tables: has weak values
** bit 4 - object is fixed (should not be collected)
** bit 0 - object is white (type 0)
** bit 1 - object is white (type 1)
** bit 2 - object is black
** bit 3 - for userdata: has been finalized
** bit 3 - for tables: has weak keys
** bit 4 - for tables: has weak values
** bit 5 - object is fixed (should not be collected)
*/
#define WHITE0BIT 0
@ -86,7 +87,7 @@
size_t luaC_separateudata (lua_State *L, int all);
void luaC_callGCTM (lua_State *L);
void luaC_sweepall (lua_State *L);
void luaC_freeall (lua_State *L);
void luaC_step (lua_State *L);
void luaC_fullgc (lua_State *L);
void luaC_link (lua_State *L, GCObject *o, lu_byte tt);

10
lstate.c
View file

@ -1,5 +1,5 @@
/*
** $Id: lstate.c,v 2.9 2004/06/17 14:06:52 roberto Exp roberto $
** $Id: lstate.c,v 2.10 2004/06/17 14:25:31 roberto Exp roberto $
** Global State
** See Copyright Notice in lua.h
*/
@ -122,9 +122,10 @@ static void preinit_state (lua_State *L, global_State *g) {
static void close_state (lua_State *L) {
global_State *g = G(L);
luaF_close(L, L->stack); /* close all upvalues for this thread */
luaC_sweepall(L); /* collect all elements */
lua_assert(g->rootgc == obj2gco(L));
luaS_freeall(L);
luaC_freeall(L); /* collect all objects */
lua_assert(g->rootgc == NULL);
lua_assert(g->strt.nuse == 0);
luaM_freearray(L, G(L)->strt.hash, G(L)->strt.size, TString *);
luaZ_freebuffer(L, &g->buff);
freestack(L, L);
lua_assert(g->nblocks == sizeof(LG));
@ -177,6 +178,7 @@ LUA_API lua_State *lua_newstate (lua_Alloc f, void *ud) {
luaZ_initbuffer(L, &g->buff);
g->panic = NULL;
g->gcstate = GCSfinalize;
g->gcgenerational = 0;
g->rootgc = obj2gco(L);
g->sweepstrgc = 0;
g->sweepgc = &g->rootgc;

7
lstate.h
View file

@ -1,5 +1,5 @@
/*
** $Id: lstate.h,v 2.4 2004/05/31 18:51:50 roberto Exp roberto $
** $Id: lstate.h,v 2.5 2004/06/02 19:07:55 roberto Exp roberto $
** Global State
** See Copyright Notice in lua.h
*/
@ -69,7 +69,9 @@ typedef struct global_State {
stringtable strt; /* hash table for strings */
lua_Alloc realloc; /* function to reallocate memory */
void *ud; /* auxiliary data to `realloc' */
int currentwhite;
lu_byte currentwhite;
lu_byte gcstate; /* state of garbage collector */
lu_byte gcgenerational;
GCObject *rootgc; /* list of all collectable objects */
GCObject *firstudata; /* udata go to the end of `rootgc' */
GCObject **sweepgc; /* position of sweep in `rootgc' */
@ -78,7 +80,6 @@ typedef struct global_State {
GCObject *grayagain; /* list of objects to be traversed atomically */
GCObject *weak; /* list of weak tables (to be cleared) */
GCObject *tmudata; /* list of userdata to be GC */
int gcstate; /* state of garbage collector */
Mbuffer buff; /* temporary buffer for string concatentation */
lu_mem GCthreshold;
lu_mem nblocks; /* number of `bytes' currently allocated */

11
lstring.c
View file

@ -1,5 +1,5 @@
/*
** $Id: lstring.c,v 2.1 2003/12/10 12:13:36 roberto Exp roberto $
** $Id: lstring.c,v 2.2 2004/04/30 20:13:38 roberto Exp roberto $
** String table (keeps all strings handled by Lua)
** See Copyright Notice in lua.h
*/
@ -19,17 +19,12 @@
void luaS_freeall (lua_State *L) {
lua_assert(G(L)->strt.nuse==0);
luaM_freearray(L, G(L)->strt.hash, G(L)->strt.size, TString *);
}
void luaS_resize (lua_State *L, int newsize) {
GCObject **newhash;
stringtable *tb;
int i;
if (G(L)->sweepstrgc > 0) return; /* cannot resize during GC traverse */
if (G(L)->gcstate == GCSsweepstring)
return; /* cannot resize during GC traverse */
newhash = luaM_newvector(L, newsize, GCObject *);
tb = &G(L)->strt;
for (i=0; i<newsize; i++) newhash[i] = NULL;

3
lstring.h
View file

@ -1,5 +1,5 @@
/*
** $Id: lstring.h,v 1.37 2002/08/16 14:45:55 roberto Exp roberto $
** $Id: lstring.h,v 1.38 2003/11/17 19:50:05 roberto Exp roberto $
** String table (keep all strings handled by Lua)
** See Copyright Notice in lua.h
*/
@ -26,7 +26,6 @@
void luaS_resize (lua_State *L, int newsize);
Udata *luaS_newudata (lua_State *L, size_t s);
void luaS_freeall (lua_State *L);
TString *luaS_newlstr (lua_State *L, const char *str, size_t l);

16
ltests.c
View file

@ -1,5 +1,5 @@
/*
** $Id: ltests.c,v 2.9 2004/06/02 19:08:52 roberto Exp roberto $
** $Id: ltests.c,v 2.10 2004/07/09 18:23:17 roberto Exp roberto $
** Internal Module for Debugging of the Lua Implementation
** See Copyright Notice in lua.h
*/
@ -153,9 +153,9 @@ void *debug_realloc (void *ud, void *block, size_t oldsize, size_t size) {
static int testobjref1 (global_State *g, GCObject *f, GCObject *t) {
if (isdead(g,t)) return 0;
if (g->gcstate == GCSpropagate)
if (g->gcstate == GCSpropagate || g->gcgenerational)
return !isblack(f) || !iswhite(t);
else if (g->gcstate == GCSfinalize)
else if (g->gcstate == GCSfinalize && !g->gcgenerational)
return iswhite(f);
else
return 1;
@ -175,7 +175,8 @@ static void printobj (global_State *g, GCObject *o) {
static int testobjref (global_State *g, GCObject *f, GCObject *t) {
int r = testobjref1(g,f,t);
if (!r) {
printf("%d(%02X) - ", g->gcstate, g->currentwhite);
printf("%d(%02X) %c - ", g->gcstate, g->currentwhite,
g->gcgenerational ? 'G' : ' ');
printobj(g, f);
printf("\t-> ");
printobj(g, t);
@ -290,9 +291,12 @@ static void checkstack (global_State *g, lua_State *L1) {
static void checkobject (global_State *g, GCObject *o) {
if (isdead(g, o))
lua_assert(g->gcstate == GCSsweepstring || g->gcstate == GCSsweep);
/* lua_assert(g->gcstate == GCSsweepstring || g->gcstate == GCSsweep);*/
{ if (!(g->gcstate == GCSsweepstring || g->gcstate == GCSsweep))
printf(">>> %d %s %02x\n", g->gcstate, luaT_typenames[o->gch.tt], o->gch.marked);
}
else {
if (g->gcstate == GCSfinalize)
if (g->gcstate == GCSfinalize && !g->gcgenerational)
lua_assert(iswhite(o));
switch (o->gch.tt) {
case LUA_TUPVAL: {