From 3ca9af51a4f060cf2178901a67a21f8269af3224 Mon Sep 17 00:00:00 2001 From: Roberto Ierusalimschy Date: Tue, 11 Jul 2006 12:53:29 -0300 Subject: emergency garbage collector (core forces a GC when allocation fails) --- lgc.c | 76 ++++++++++++++++++++++++++++++++++++++++--------------------------- 1 file changed, 46 insertions(+), 30 deletions(-) (limited to 'lgc.c') diff --git a/lgc.c b/lgc.c index 935d8c1b..93316741 100644 --- a/lgc.c +++ b/lgc.c @@ -1,5 +1,5 @@ /* -** $Id: lgc.c,v 2.37 2005/12/22 16:19:56 roberto Exp roberto $ +** $Id: lgc.c,v 2.38 2006/05/24 14:34:06 roberto Exp roberto $ ** Garbage Collector ** See Copyright Notice in lua.h */ @@ -52,7 +52,7 @@ #define markvalue(g,o) { checkconsistency(o); \ if (iscollectable(o) && iswhite(gcvalue(o))) reallymarkobject(g,gcvalue(o)); } -#define markobject(g,t) { if (iswhite(obj2gco(t))) \ +#define markobject(g,t) { if ((t) && iswhite(obj2gco(t))) \ reallymarkobject(g, obj2gco(t)); } @@ -76,7 +76,7 @@ static void reallymarkobject (global_State *g, GCObject *o) { case LUA_TUSERDATA: { Table *mt = gco2u(o)->metatable; gray2black(o); /* udata are never gray */ - if (mt) markobject(g, mt); + markobject(g, mt); markobject(g, gco2u(o)->env); return; } @@ -160,8 +160,7 @@ static int traversetable (global_State *g, Table *h) { int weakkey = 0; int weakvalue = 0; const TValue *mode; - if (h->metatable) - markobject(g, h->metatable); + markobject(g, h->metatable); mode = gfasttm(g, h->metatable, TM_MODE); if (mode && ttisstring(mode)) { /* is there a weak mode? */ weakkey = (strchr(svalue(mode), 'k') != NULL); @@ -209,10 +208,8 @@ static void traverseproto (global_State *g, Proto *f) { if (f->upvalues[i]) stringmark(f->upvalues[i]); } - for (i=0; isizep; i++) { /* mark nested protos */ - if (f->p[i]) - markobject(g, f->p[i]); - } + for (i=0; isizep; i++) /* mark nested protos */ + markobject(g, f->p[i]); for (i=0; isizelocvars; i++) { /* mark local-variable names */ if (f->locvars[i].varname) stringmark(f->locvars[i].varname); @@ -256,6 +253,8 @@ static void checkstacksizes (lua_State *L, StkId max) { static void traversestack (global_State *g, lua_State *l) { StkId o, lim; CallInfo *ci; + if (l->stack == NULL || l->base_ci == NULL) + return; /* stack not completely built yet */ markvalue(g, gt(l)); lim = l->top; for (ci = l->base_ci; ci <= l->ci; ci++) { @@ -266,7 +265,8 @@ static void traversestack (global_State *g, lua_State *l) { markvalue(g, o); for (; o <= lim; o++) setnilvalue(o); - checkstacksizes(l, lim); + if (!g->emergencygc) /* cannot change stack in emergency... */ + checkstacksizes(l, lim); /* ...(interpreter does not expect that change) */ } @@ -442,11 +442,9 @@ static void checkSizes (lua_State *L) { } -static void GCTM (lua_State *L) { - global_State *g = G(L); +static Udata *udata2finalize (global_State *g) { GCObject *o = g->tmudata->gch.next; /* get first element */ Udata *udata = rawgco2u(o); - const TValue *tm; /* remove udata from `tmudata' */ if (o == g->tmudata) /* last element? */ g->tmudata = NULL; @@ -455,7 +453,14 @@ static void GCTM (lua_State *L) { udata->uv.next = g->mainthread->next; /* return it to `root' list */ g->mainthread->next = o; makewhite(g, o); - tm = fasttm(L, udata->uv.metatable, TM_GC); + return udata; +} + + +static void GCTM (lua_State *L) { + global_State *g = G(L); + Udata *udata = udata2finalize(g); + const TValue *tm = fasttm(L, udata->uv.metatable, TM_GC); if (tm != NULL) { lu_byte oldah = L->allowhook; lu_mem oldt = g->GCthreshold; @@ -475,8 +480,17 @@ static void GCTM (lua_State *L) { ** Call all GC tag methods */ void luaC_callGCTM (lua_State *L) { - while (G(L)->tmudata) + global_State *g = G(L); + GCObject *last = g->tmudata; + GCObject *curr; + if (last == NULL) return; /* empty list? */ + do { + curr = g->tmudata->gch.next; /* element to be collected */ GCTM(L); + } while (curr != last); /* go only until original last */ + /* do not finalize new udata created during previous finalizations */ + while (g->tmudata) + udata2finalize(g); /* simply remove them from list */ } @@ -493,7 +507,7 @@ void luaC_freeall (lua_State *L) { static void markmt (global_State *g) { int i; for (i=0; imt[i]) markobject(g, g->mt[i]); + markobject(g, g->mt[i]); } @@ -553,6 +567,10 @@ static void atomic (lua_State *L) { } +#define correctestimate(g,s) {lu_mem old = g->totalbytes; s; \ + lua_assert(old >= g->totalbytes); g->estimate -= old - g->totalbytes;} + + static l_mem singlestep (lua_State *L) { global_State *g = G(L); /*lua_checkmemory(L);*/ @@ -570,23 +588,15 @@ static l_mem singlestep (lua_State *L) { } } case GCSsweepstring: { - lu_mem old = g->totalbytes; - sweepwholelist(L, &g->strt.hash[g->sweepstrgc++]); + correctestimate(g, sweepwholelist(L, &g->strt.hash[g->sweepstrgc++])); if (g->sweepstrgc >= g->strt.size) /* nothing more to sweep? */ g->gcstate = GCSsweep; /* end sweep-string phase */ - lua_assert(old >= g->totalbytes); - g->estimate -= old - g->totalbytes; return GCSWEEPCOST; } case GCSsweep: { - lu_mem old = g->totalbytes; - g->sweepgc = sweeplist(L, g->sweepgc, GCSWEEPMAX); - if (*g->sweepgc == NULL) { /* nothing more to sweep? */ - checkSizes(L); + correctestimate(g, g->sweepgc = sweeplist(L, g->sweepgc, GCSWEEPMAX)); + if (*g->sweepgc == NULL) /* nothing more to sweep? */ g->gcstate = GCSfinalize; /* end sweep phase */ - } - lua_assert(old >= g->totalbytes); - g->estimate -= old - g->totalbytes; return GCSWEEPMAX*GCSWEEPCOST; } case GCSfinalize: { @@ -597,6 +607,7 @@ static l_mem singlestep (lua_State *L) { return GCFINALIZECOST; } else { + correctestimate(g, checkSizes(L)); g->gcstate = GCSpause; /* end collection */ g->gcdept = 0; return 0; @@ -610,6 +621,7 @@ static l_mem singlestep (lua_State *L) { void luaC_step (lua_State *L) { global_State *g = G(L); l_mem lim = (GCSTEPSIZE/100) * g->gcstepmul; + lua_assert(!g->emergencygc); if (lim == 0) lim = (MAX_LUMEM-1)/2; /* no limit */ g->gcdept += g->totalbytes - g->GCthreshold; @@ -633,8 +645,10 @@ void luaC_step (lua_State *L) { } -void luaC_fullgc (lua_State *L) { +void luaC_fullgc (lua_State *L, int isemergency) { + int stopstate; global_State *g = G(L); + g->emergencygc = isemergency; if (g->gcstate <= GCSpropagate) { /* reset sweep marks to sweep all elements (returning them to white) */ g->sweepstrgc = 0; @@ -652,10 +666,12 @@ void luaC_fullgc (lua_State *L) { singlestep(L); } markroot(L); - while (g->gcstate != GCSpause) { + /* do not run finalizers during emergency GC */ + stopstate = isemergency ? GCSfinalize : GCSpause; + while (g->gcstate != stopstate) singlestep(L); - } setthreshold(g); + g->emergencygc = 0; } -- cgit v1.2.3-55-g6feb