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-rw-r--r--apps/plugins/lua/lgc.c1417
1 files changed, 963 insertions, 454 deletions
diff --git a/apps/plugins/lua/lgc.c b/apps/plugins/lua/lgc.c
index d9e0b78294..52460dcdd5 100644
--- a/apps/plugins/lua/lgc.c
+++ b/apps/plugins/lua/lgc.c
@@ -1,5 +1,5 @@
/*
-** $Id: lgc.c,v 2.38.1.1 2007/12/27 13:02:25 roberto Exp $
+** $Id: lgc.c,v 2.140.1.2 2013/04/26 18:22:05 roberto Exp $
** Garbage Collector
** See Copyright Notice in lua.h
*/
@@ -23,376 +23,663 @@
#include "ltm.h"
-#define GCSTEPSIZE 1024u
-#define GCSWEEPMAX 40
-#define GCSWEEPCOST 10
-#define GCFINALIZECOST 100
+/*
+** 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)
-#define maskmarks cast_byte(~(bitmask(BLACKBIT)|WHITEBITS))
+/* maximum number of elements to sweep in each single step */
+#define GCSWEEPMAX (cast_int((GCSTEPSIZE / GCSWEEPCOST) / 4))
-#define makewhite(g,x) \
- ((x)->gch.marked = cast_byte(((x)->gch.marked & maskmarks) | luaC_white(g)))
+/* maximum number of finalizers to call in each GC step */
+#define GCFINALIZENUM 4
+
+
+/*
+** 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
-#define white2gray(x) reset2bits((x)->gch.marked, WHITE0BIT, WHITE1BIT)
-#define black2gray(x) resetbit((x)->gch.marked, BLACKBIT)
-#define stringmark(s) reset2bits((s)->tsv.marked, WHITE0BIT, WHITE1BIT)
+/*
+** 'makewhite' erases all color bits plus the old bit and then
+** sets only the current white bit
+*/
+#define maskcolors (~(bit2mask(BLACKBIT, OLDBIT) | 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 isfinalized(u) testbit((u)->marked, FINALIZEDBIT)
-#define markfinalized(u) l_setbit((u)->marked, FINALIZEDBIT)
+#define isfinalized(x) testbit(gch(x)->marked, FINALIZEDBIT)
-#define KEYWEAK bitmask(KEYWEAKBIT)
-#define VALUEWEAK bitmask(VALUEWEAKBIT)
+#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 (iscollectable(o) && iswhite(gcvalue(o))) reallymarkobject(g,gcvalue(o)); }
+ if (valiswhite(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)); }
+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)))
+
-#define setthreshold(g) (g->GCthreshold = (g->estimate/100) * g->gcpause)
+/*
+** 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 (iscollectable(gkey(n)))
- setttype(gkey(n), LUA_TDEADKEY); /* dead key; remove it */
+ 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);
+ if (keepinvariantout(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 prototypes. When creating first closure (cache is
+** NULL), use a forward barrier; this may be the only closure of the
+** prototype (if it is a "regular" function, with a single instance)
+** and the prototype may be big, so it is better to avoid traversing
+** it again. Otherwise, use a backward barrier, to avoid marking all
+** possible instances.
+*/
+LUAI_FUNC void luaC_barrierproto_ (lua_State *L, Proto *p, Closure *c) {
+ global_State *g = G(L);
+ lua_assert(isblack(obj2gco(p)));
+ if (p->cache == NULL) { /* first time? */
+ luaC_objbarrier(L, p, c);
+ }
+ else { /* use a backward barrier */
+ black2gray(obj2gco(p)); /* make prototype gray (again) */
+ p->gclist = g->grayagain;
+ g->grayagain = obj2gco(p);
+ }
+}
+
+
+/*
+** check color (and invariants) for an upvalue that was closed,
+** i.e., moved into the 'allgc' list
+*/
+void luaC_checkupvalcolor (global_State *g, UpVal *uv) {
+ GCObject *o = obj2gco(uv);
+ lua_assert(!isblack(o)); /* open upvalues are never black */
+ if (isgray(o)) {
+ if (keepinvariant(g)) {
+ resetoldbit(o); /* see MOVE OLD rule */
+ gray2black(o); /* it is being visited now */
+ markvalue(g, uv->v);
+ }
+ else {
+ lua_assert(issweepphase(g));
+ makewhite(g, o);
+ }
+ }
+}
+
+
+/*
+** create a new collectable object (with given type and size) and link
+** it to '*list'. 'offset' tells how many bytes to allocate before the
+** object itself (used only by states).
+*/
+GCObject *luaC_newobj (lua_State *L, int tt, size_t sz, GCObject **list,
+ int offset) {
+ global_State *g = G(L);
+ char *raw = cast(char *, luaM_newobject(L, novariant(tt), sz));
+ GCObject *o = obj2gco(raw + offset);
+ if (list == NULL)
+ list = &g->allgc; /* standard list for collectable objects */
+ gch(o)->marked = luaC_white(g);
+ gch(o)->tt = tt;
+ gch(o)->next = *list;
+ *list = 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) {
- lua_assert(iswhite(o) && !isdead(g, o));
+ lu_mem size;
white2gray(o);
- switch (o->gch.tt) {
- case LUA_TSTRING: {
- return;
+ switch (gch(o)->tt) {
+ case LUA_TSHRSTR:
+ case LUA_TLNGSTR: {
+ size = sizestring(gco2ts(o));
+ break; /* nothing else to mark; make it black */
}
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;
+ size = sizeudata(gco2u(o));
+ break;
}
case LUA_TUPVAL: {
UpVal *uv = gco2uv(o);
markvalue(g, uv->v);
- if (uv->v == &uv->u.value) /* closed? */
- gray2black(o); /* open upvalues are never black */
+ if (uv->v != &uv->u.value) /* open? */
+ return; /* open upvalues remain gray */
+ size = sizeof(UpVal);
+ break;
+ }
+ case LUA_TLCL: {
+ gco2lcl(o)->gclist = g->gray;
+ g->gray = o;
return;
}
- case LUA_TFUNCTION: {
- gco2cl(o)->c.gclist = g->gray;
+ case LUA_TCCL: {
+ gco2ccl(o)->gclist = g->gray;
g->gray = o;
- break;
+ return;
}
case LUA_TTABLE: {
- gco2h(o)->gclist = g->gray;
- g->gray = o;
- break;
+ linktable(gco2t(o), &g->gray);
+ return;
}
case LUA_TTHREAD: {
gco2th(o)->gclist = g->gray;
g->gray = o;
- break;
+ return;
}
case LUA_TPROTO: {
gco2p(o)->gclist = g->gray;
g->gray = o;
- break;
+ return;
}
- default: lua_assert(0);
+ default: lua_assert(0); return;
}
+ gray2black(o);
+ g->GCmemtrav += size;
+}
+
+
+/*
+** 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]);
}
-static void marktmu (global_State *g) {
- GCObject *u = g->tmudata;
- if (u) {
- do {
- u = u->gch.next;
- makewhite(g, u); /* may be marked, if left from previous GC */
- reallymarkobject(g, u);
- } while (u != g->tmudata);
+/*
+** 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) {
+ makewhite(g, o);
+ reallymarkobject(g, o);
}
}
-/* move `dead' udata that need finalization to list `tmudata' */
-size_t luaC_separateudata (lua_State *L, int all) {
- global_State *g = G(L);
- size_t deadmem = 0;
- GCObject **p = &g->mainthread->next;
- GCObject *curr;
- while ((curr = *p) != NULL) {
- if (!(iswhite(curr) || all) || isfinalized(gco2u(curr)))
- p = &curr->gch.next; /* don't bother with them */
- else if (fasttm(L, gco2u(curr)->metatable, TM_GC) == NULL) {
- markfinalized(gco2u(curr)); /* don't need finalization */
- p = &curr->gch.next;
- }
- else { /* must call its gc method */
- deadmem += sizeudata(gco2u(curr));
- markfinalized(gco2u(curr));
- *p = curr->gch.next;
- /* link `curr' at the end of `tmudata' list */
- if (g->tmudata == NULL) /* list is empty? */
- g->tmudata = curr->gch.next = curr; /* creates a circular list */
- else {
- curr->gch.next = g->tmudata->gch.next;
- g->tmudata->gch.next = curr;
- g->tmudata = curr;
- }
- }
+/*
+** mark all values stored in marked open upvalues. (See comment in
+** 'lstate.h'.)
+*/
+static void remarkupvals (global_State *g) {
+ UpVal *uv;
+ for (uv = g->uvhead.u.l.next; uv != &g->uvhead; uv = uv->u.l.next) {
+ if (isgray(obj2gco(uv)))
+ markvalue(g, uv->v);
}
- return deadmem;
}
-static int traversetable (global_State *g, Table *h) {
- int i;
- int weakkey = 0;
- int weakvalue = 0;
- const TValue *mode;
- if (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);
- weakvalue = (strchr(svalue(mode), 'v') != NULL);
- if (weakkey || weakvalue) { /* is really weak? */
- h->marked &= ~(KEYWEAK | VALUEWEAK); /* clear bits */
- h->marked |= cast_byte((weakkey << KEYWEAKBIT) |
- (weakvalue << VALUEWEAKBIT));
- h->gclist = g->weak; /* must be cleared after GC, ... */
- g->weak = obj2gco(h); /* ... so put in the appropriate list */
- }
- }
- if (weakkey && weakvalue) return 1;
- if (!weakvalue) {
- i = h->sizearray;
- while (i--)
- markvalue(g, &h->array[i]);
- }
- i = sizenode(h);
- while (i--) {
- Node *n = gnode(h, i);
- lua_assert(ttype(gkey(n)) != LUA_TDEADKEY || ttisnil(gval(n)));
- if (ttisnil(gval(n)))
- removeentry(n); /* remove empty entries */
+/*
+** mark root set and reset all gray lists, to start a new
+** incremental (or full) 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)));
- if (!weakkey) markvalue(g, gkey(n));
- if (!weakvalue) markvalue(g, gval(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 */
}
}
- return weakkey || weakvalue;
+ if (hasclears)
+ linktable(h, &g->weak); /* has to be cleared later */
+ else /* no white values */
+ linktable(h, &g->grayagain); /* no need to clean */
}
-/*
-** All marks are conditional because a GC may happen while the
-** prototype is still being created
-*/
-static void traverseproto (global_State *g, Proto *f) {
+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;
- if (f->source) stringmark(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 */
- if (f->upvalues[i])
- stringmark(f->upvalues[i]);
- }
- for (i=0; i<f->sizep; i++) { /* mark nested protos */
- if (f->p[i])
- markobject(g, f->p[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]));
+ }
}
- for (i=0; i<f->sizelocvars; i++) { /* mark local-variable names */
- if (f->locvars[i].varname)
- stringmark(f->locvars[i].varname);
+ /* 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 traverseclosure (global_State *g, Closure *cl) {
- markobject(g, cl->c.env);
- if (cl->c.isC) {
- int i;
- for (i=0; i<cl->c.nupvalues; i++) /* mark its upvalues */
- markvalue(g, &cl->c.upvalue[i]);
+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 */
+ }
}
- else {
- int i;
- lua_assert(cl->l.nupvalues == cl->l.p->nups);
- markobject(g, cl->l.p);
- for (i=0; i<cl->l.nupvalues; i++) /* mark its upvalues */
- markobject(g, cl->l.upvals[i]);
+}
+
+
+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 void checkstacksizes (lua_State *L, StkId max) {
- int ci_used = cast_int(L->ci - L->base_ci); /* number of `ci' in use */
- int s_used = cast_int(max - L->stack); /* part of stack in use */
- if (L->size_ci > LUAI_MAXCALLS) /* handling overflow? */
- return; /* do not touch the stacks */
- if (4*ci_used < L->size_ci && 2*BASIC_CI_SIZE < L->size_ci)
- luaD_reallocCI(L, L->size_ci/2); /* still big enough... */
- condhardstacktests(luaD_reallocCI(L, ci_used + 1));
- if (4*s_used < L->stacksize &&
- 2*(BASIC_STACK_SIZE+EXTRA_STACK) < L->stacksize)
- luaD_reallocstack(L, L->stacksize/2); /* still big enough... */
- condhardstacktests(luaD_reallocstack(L, s_used));
+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 void traversestack (global_State *g, lua_State *l) {
- StkId o, lim;
- CallInfo *ci;
- markvalue(g, gt(l));
- lim = l->top;
- for (ci = l->base_ci; ci <= l->ci; ci++) {
- lua_assert(ci->top <= l->stack_last);
- if (lim < ci->top) lim = ci->top;
- }
- for (o = l->stack; o < l->top; o++)
+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);
+}
+
+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 */
+ markobject(g, cl->upvals[i]);
+ 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 */
+ for (; o < th->top; o++) /* mark live elements in the stack */
markvalue(g, o);
- for (; o <= lim; o++)
- setnilvalue(o);
- checkstacksizes(l, lim);
+ if (g->gcstate == GCSatomic) { /* final traversal? */
+ StkId lim = th->stack + th->stacksize; /* real end of stack */
+ for (; o < lim; o++) /* clear not-marked stack slice */
+ setnilvalue(o);
+ }
+ else { /* count call infos to compute size */
+ CallInfo *ci;
+ for (ci = &th->base_ci; ci != th->ci; ci = ci->next)
+ n++;
+ }
+ return sizeof(lua_State) + sizeof(TValue) * th->stacksize +
+ sizeof(CallInfo) * n;
}
/*
-** traverse one gray object, turning it to black.
-** Returns `quantity' traversed.
+** traverse one gray object, turning it to black (except for threads,
+** which are always gray).
*/
-static l_mem propagatemark (global_State *g) {
+static void propagatemark (global_State *g) {
+ lu_mem size;
GCObject *o = g->gray;
lua_assert(isgray(o));
gray2black(o);
- switch (o->gch.tt) {
+ switch (gch(o)->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);
- }
- 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);
+ 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;
+ g->gray = th->gclist; /* remove from 'gray' list */
th->gclist = g->grayagain;
- g->grayagain = o;
+ g->grayagain = o; /* insert into 'grayagain' list */
black2gray(o);
- traversestack(g, th);
- return sizeof(lua_State) + sizeof(TValue) * th->stacksize +
- sizeof(CallInfo) * th->size_ci;
+ size = traversestack(g, th);
+ 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;
+ g->gray = p->gclist; /* remove from 'gray' list */
+ size = traverseproto(g, p);
+ break;
}
- default: lua_assert(0); return 0;
+ default: lua_assert(0); return;
}
+ g->GCmemtrav += size;
}
-static size_t propagateall (global_State *g) {
- size_t m = 0;
- while (g->gray) m += propagatemark(g);
- return m;
+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' */
+}
+
/*
-** The next function 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 userdata
-** being finalized, keep them in keys, but not in values
+** 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 int iscleared (const TValue *o, int iskey) {
- if (!iscollectable(o)) return 0;
- if (ttisstring(o)) {
- stringmark(rawtsvalue(o)); /* strings are `values', so are never weak */
- return 0;
- }
- return iswhite(gcvalue(o)) ||
- (ttisuserdata(o) && (!iskey && isfinalized(uvalue(o))));
+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);
}
+/* }====================================================== */
+
/*
-** clear collected entries from weaktables
+** {======================================================
+** Sweep Functions
+** =======================================================
*/
-static void cleartable (GCObject *l) {
- while (l) {
- Table *h = gco2h(l);
- int i = h->sizearray;
- lua_assert(testbit(h->marked, VALUEWEAKBIT) ||
- testbit(h->marked, KEYWEAKBIT));
- if (testbit(h->marked, VALUEWEAKBIT)) {
- while (i--) {
- TValue *o = &h->array[i];
- if (iscleared(o, 0)) /* value was collected? */
- setnilvalue(o); /* remove value */
+
+
+/*
+** 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 */
}
}
- i = sizenode(h);
- while (i--) {
- Node *n = gnode(h, i);
- if (!ttisnil(gval(n)) && /* non-empty entry? */
- (iscleared(key2tval(n), 1) || iscleared(gval(n), 0))) {
+ }
+}
+
+
+/*
+** 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); /* remove entry from table */
+ removeentry(n); /* and remove entry from table */
}
}
- l = h->gclist;
}
}
static void freeobj (lua_State *L, GCObject *o) {
- switch (o->gch.tt) {
+ switch (gch(o)->tt) {
case LUA_TPROTO: luaF_freeproto(L, gco2p(o)); break;
- case LUA_TFUNCTION: luaF_freeclosure(L, gco2cl(o)); break;
- case LUA_TUPVAL: luaF_freeupval(L, gco2uv(o)); break;
- case LUA_TTABLE: luaH_free(L, gco2h(o)); break;
- case LUA_TTHREAD: {
- lua_assert(gco2th(o) != L && gco2th(o) != G(L)->mainthread);
- luaE_freethread(L, gco2th(o));
+ case LUA_TLCL: {
+ luaM_freemem(L, o, sizeLclosure(gco2lcl(o)->nupvalues));
break;
}
- case LUA_TSTRING: {
- G(L)->strt.nuse--;
- luaM_freemem(L, o, sizestring(gco2ts(o)));
+ case LUA_TCCL: {
+ luaM_freemem(L, o, sizeCclosure(gco2ccl(o)->nupvalues));
break;
}
- case LUA_TUSERDATA: {
- luaM_freemem(L, o, sizeudata(gco2u(o)));
+ case LUA_TUPVAL: luaF_freeupval(L, gco2uv(o)); 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:
+ G(L)->strt.nuse--;
+ /* go through */
+ case LUA_TLNGSTR: {
+ luaM_freemem(L, o, sizestring(gco2ts(o)));
break;
}
default: lua_assert(0);
@@ -400,312 +687,534 @@ static void freeobj (lua_State *L, GCObject *o) {
}
-
#define sweepwholelist(L,p) sweeplist(L,p,MAX_LUMEM)
+static GCObject **sweeplist (lua_State *L, GCObject **p, lu_mem count);
+/*
+** sweep the (open) upvalues of a thread and resize its stack and
+** list of call-info structures.
+*/
+static void sweepthread (lua_State *L, lua_State *L1) {
+ if (L1->stack == NULL) return; /* stack not completely built yet */
+ sweepwholelist(L, &L1->openupval); /* sweep open upvalues */
+ luaE_freeCI(L1); /* free extra CallInfo slots */
+ /* should not change the stack during an emergency gc cycle */
+ if (G(L)->gckind != KGC_EMERGENCY)
+ luaD_shrinkstack(L1);
+}
+
+
+/*
+** 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.
+** In non-generational mode, change all non-dead objects back to white,
+** preparing for next collection cycle.
+** In generational mode, keep black objects black, and also mark them as
+** old; stop when hitting an old object, as all objects after that
+** one will be old too.
+** When object is a thread, sweep its list of open upvalues too.
+*/
static GCObject **sweeplist (lua_State *L, GCObject **p, lu_mem count) {
- GCObject *curr;
global_State *g = G(L);
- int deadmask = otherwhite(g);
- while ((curr = *p) != NULL && count-- > 0) {
- if (curr->gch.tt == LUA_TTHREAD) /* sweep open upvalues of each thread */
- sweepwholelist(L, &gco2th(curr)->openupval);
- if ((curr->gch.marked ^ WHITEBITS) & deadmask) { /* not dead? */
- lua_assert(!isdead(g, curr) || testbit(curr->gch.marked, FIXEDBIT));
- makewhite(g, curr); /* make it white (for next cycle) */
- p = &curr->gch.next;
- }
- else { /* must erase `curr' */
- lua_assert(isdead(g, curr) || deadmask == bitmask(SFIXEDBIT));
- *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);
+ int ow = otherwhite(g);
+ int toclear, toset; /* bits to clear and to set in all live objects */
+ int tostop; /* stop sweep when this is true */
+ if (isgenerational(g)) { /* generational mode? */
+ toclear = ~0; /* clear nothing */
+ toset = bitmask(OLDBIT); /* set the old bit of all surviving objects */
+ tostop = bitmask(OLDBIT); /* do not sweep old generation */
+ }
+ else { /* normal mode */
+ toclear = maskcolors; /* clear all color bits + old bit */
+ toset = luaC_white(g); /* make object white */
+ tostop = 0; /* do not stop */
+ }
+ 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 {
+ if (testbits(marked, tostop))
+ return NULL; /* stop sweeping this list */
+ if (gch(curr)->tt == LUA_TTHREAD)
+ sweepthread(L, gco2th(curr)); /* sweep thread's upvalues */
+ /* update marks */
+ gch(curr)->marked = cast_byte((marked & toclear) | toset);
+ 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
+** =======================================================
+*/
static void checkSizes (lua_State *L) {
global_State *g = G(L);
- /* check size of string hash */
- if (g->strt.nuse < cast(lu_int32, g->strt.size/4) &&
- g->strt.size > MINSTRTABSIZE*2)
- luaS_resize(L, g->strt.size/2); /* table is too big */
- /* check size of buffer */
- if (luaZ_sizebuffer(&g->buff) > LUA_MINBUFFER*2) { /* buffer too big? */
- size_t newsize = luaZ_sizebuffer(&g->buff) / 2;
- luaZ_resizebuffer(L, &g->buff, newsize);
+ if (g->gckind != KGC_EMERGENCY) { /* do not change sizes in emergency */
+ int hs = g->strt.size / 2; /* half the size of the string table */
+ if (g->strt.nuse < cast(lu_int32, hs)) /* using less than that half? */
+ luaS_resize(L, hs); /* halve its size */
+ luaZ_freebuffer(L, &g->buff); /* free concatenation buffer */
}
}
-static void GCTM (lua_State *L) {
+static GCObject *udata2finalize (global_State *g) {
+ GCObject *o = g->tobefnz; /* get first element */
+ lua_assert(isfinalized(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, SEPARATED); /* mark that it is not in 'tobefnz' */
+ lua_assert(!isold(o)); /* see MOVE OLD rule */
+ if (!keepinvariantout(g)) /* not keeping invariant? */
+ 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);
- 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;
- else
- g->tmudata->gch.next = udata->uv.next;
- 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);
- if (tm != NULL) {
+ 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;
- lu_mem oldt = g->GCthreshold;
- L->allowhook = 0; /* stop debug hooks during GC tag method */
- g->GCthreshold = 2*g->totalbytes; /* avoid GC steps */
- setobj2s(L, L->top, tm);
- setuvalue(L, L->top+1, udata);
- L->top += 2;
- luaD_call(L, L->top - 2, 0);
+ 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->GCthreshold = oldt; /* restore threshold */
+ 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 GC tag methods
+** move all unreachable objects (or 'all' objects) that need
+** finalization from list 'finobj' to list 'tobefnz' (to be finalized)
*/
-void luaC_callGCTM (lua_State *L) {
- while (G(L)->tmudata)
- GCTM(L);
+static void separatetobefnz (lua_State *L, int all) {
+ global_State *g = G(L);
+ GCObject **p = &g->finobj;
+ GCObject *curr;
+ GCObject **lastnext = &g->tobefnz;
+ /* find last 'next' field in 'tobefnz' list (to add elements in its end) */
+ while (*lastnext != NULL)
+ lastnext = &gch(*lastnext)->next;
+ while ((curr = *p) != NULL) { /* traverse all finalizable objects */
+ lua_assert(!isfinalized(curr));
+ lua_assert(testbit(gch(curr)->marked, SEPARATED));
+ if (!(iswhite(curr) || all)) /* not being collected? */
+ p = &gch(curr)->next; /* don't bother with it */
+ else {
+ l_setbit(gch(curr)->marked, FINALIZEDBIT); /* won't be finalized again */
+ *p = gch(curr)->next; /* remove 'curr' from 'finobj' list */
+ gch(curr)->next = *lastnext; /* link at the end of 'tobefnz' list */
+ *lastnext = curr;
+ lastnext = &gch(curr)->next;
+ }
+ }
}
-void luaC_freeall (lua_State *L) {
+/*
+** 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);
- int i;
- g->currentwhite = WHITEBITS | bitmask(SFIXEDBIT); /* mask to collect all elements */
- sweepwholelist(L, &g->rootgc);
- for (i = 0; i < g->strt.size; i++) /* free all string lists */
- sweepwholelist(L, &g->strt.hash[i]);
+ if (testbit(gch(o)->marked, SEPARATED) || /* obj. is already separated... */
+ isfinalized(o) || /* ... or is finalized... */
+ gfasttm(g, mt, TM_GC) == NULL) /* or has no finalizer? */
+ return; /* nothing to be done */
+ else { /* move 'o' to 'finobj' list */
+ GCObject **p;
+ GCheader *ho = gch(o);
+ if (g->sweepgc == &ho->next) { /* avoid removing current sweep object */
+ lua_assert(issweepphase(g));
+ g->sweepgc = sweeptolive(L, g->sweepgc, NULL);
+ }
+ /* search for pointer pointing to 'o' */
+ for (p = &g->allgc; *p != o; p = &gch(*p)->next) { /* empty */ }
+ *p = ho->next; /* remove 'o' from root list */
+ ho->next = g->finobj; /* link it in list 'finobj' */
+ g->finobj = o;
+ l_setbit(ho->marked, SEPARATED); /* mark it as such */
+ if (!keepinvariantout(g)) /* not keeping invariant? */
+ makewhite(g, o); /* "sweep" object */
+ else
+ resetoldbit(o); /* see MOVE OLD rule */
+ }
}
+/* }====================================================== */
-static void markmt (global_State *g) {
- int i;
- for (i=0; i<NUM_TAGS; i++)
- if (g->mt[i]) markobject(g, g->mt[i]);
+
+/*
+** {======================================================
+** 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 estimate) {
+ l_mem debt, threshold;
+ estimate = estimate / PAUSEADJ; /* adjust 'estimate' */
+ threshold = (g->gcpause < MAX_LMEM / estimate) /* overflow? */
+ ? estimate * g->gcpause /* no overflow */
+ : MAX_LMEM; /* overflow; truncate to maximum */
+ debt = -cast(l_mem, threshold - gettotalbytes(g));
+ luaE_setdebt(g, debt);
}
-/* mark root set */
-static void markroot (lua_State *L) {
+#define sweepphases \
+ (bitmask(GCSsweepstring) | bitmask(GCSsweepudata) | bitmask(GCSsweep))
+
+
+/*
+** enter first sweep phase (strings) and prepare pointers for other
+** sweep phases. The calls to 'sweeptolive' make pointers 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);
- g->gray = NULL;
- g->grayagain = NULL;
- g->weak = NULL;
- markobject(g, g->mainthread);
- /* make global table be traversed before main stack */
- markvalue(g, gt(g->mainthread));
- markvalue(g, registry(L));
- markmt(g);
- g->gcstate = GCSpropagate;
+ int n = 0;
+ g->gcstate = GCSsweepstring;
+ lua_assert(g->sweepgc == NULL && g->sweepfin == NULL);
+ /* prepare to sweep strings, finalizable objects, and regular objects */
+ g->sweepstrgc = 0;
+ g->sweepfin = sweeptolive(L, &g->finobj, &n);
+ g->sweepgc = sweeptolive(L, &g->allgc, &n);
+ return n;
}
-static void remarkupvals (global_State *g) {
- UpVal *uv;
- for (uv = g->uvhead.u.l.next; uv != &g->uvhead; uv = uv->u.l.next) {
- lua_assert(uv->u.l.next->u.l.prev == uv && uv->u.l.prev->u.l.next == uv);
- if (isgray(obj2gco(uv)))
- markvalue(g, uv->v);
+/*
+** change GC mode
+*/
+void luaC_changemode (lua_State *L, int mode) {
+ global_State *g = G(L);
+ if (mode == g->gckind) return; /* nothing to change */
+ if (mode == KGC_GEN) { /* change to generational mode */
+ /* make sure gray lists are consistent */
+ luaC_runtilstate(L, bitmask(GCSpropagate));
+ g->GCestimate = gettotalbytes(g);
+ g->gckind = KGC_GEN;
+ }
+ else { /* change to incremental mode */
+ /* sweep all objects to turn them back to white
+ (as white has not changed, nothing extra will be collected) */
+ g->gckind = KGC_NORMAL;
+ entersweep(L);
+ luaC_runtilstate(L, ~sweepphases);
}
}
-static void atomic (lua_State *L) {
+/*
+** call all pending finalizers
+*/
+static void callallpendingfinalizers (lua_State *L, int propagateerrors) {
global_State *g = G(L);
- size_t udsize; /* total size of userdata to be finalized */
- /* remark occasional upvalues of (maybe) dead threads */
- remarkupvals(g);
- /* traverse objects cautch by write barrier and by 'remarkupvals' */
- propagateall(g);
- /* remark weak tables */
- g->gray = g->weak;
- g->weak = NULL;
+ while (g->tobefnz) {
+ resetoldbit(g->tobefnz);
+ GCTM(L, propagateerrors);
+ }
+}
+
+
+void luaC_freeallobjects (lua_State *L) {
+ global_State *g = G(L);
+ int i;
+ separatetobefnz(L, 1); /* separate all objects with finalizers */
+ lua_assert(g->finobj == NULL);
+ callallpendingfinalizers(L, 0);
+ g->currentwhite = WHITEBITS; /* this "white" makes all objects look dead */
+ g->gckind = KGC_NORMAL;
+ sweepwholelist(L, &g->finobj); /* finalizers can create objs. in 'finobj' */
+ sweepwholelist(L, &g->allgc);
+ for (i = 0; i < g->strt.size; i++) /* free all string lists */
+ sweepwholelist(L, &g->strt.hash[i]);
+ lua_assert(g->strt.nuse == 0);
+}
+
+
+static l_mem atomic (lua_State *L) {
+ global_State *g = G(L);
+ l_mem work = -cast(l_mem, g->GCmemtrav); /* start counting work */
+ GCObject *origweak, *origall;
lua_assert(!iswhite(obj2gco(g->mainthread)));
markobject(g, L); /* mark running thread */
- markmt(g); /* mark basic metatables (again) */
- propagateall(g);
- /* remark gray again */
- g->gray = g->grayagain;
- g->grayagain = NULL;
- propagateall(g);
- udsize = luaC_separateudata(L, 0); /* separate userdata to be finalized */
- marktmu(g); /* mark `preserved' userdata */
- udsize += propagateall(g); /* remark, to propagate `preserveness' */
- cleartable(g->weak); /* remove collected objects from weak tables */
- /* flip current white */
- g->currentwhite = cast_byte(otherwhite(g));
- g->sweepstrgc = 0;
- g->sweepgc = &g->rootgc;
- g->gcstate = GCSsweepstring;
- g->estimate = g->totalbytes - udsize; /* first estimate */
+ /* 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);
+ work -= g->GCmemtrav; /* 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(L, 0); /* separate objects to be finalized */
+ markbeingfnz(g); /* mark objects that will be finalized */
+ propagateall(g); /* remark, to propagate `preserveness' */
+ work -= g->GCmemtrav; /* 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 l_mem singlestep (lua_State *L) {
+static lu_mem singlestep (lua_State *L) {
global_State *g = G(L);
- /*lua_checkmemory(L);*/
switch (g->gcstate) {
case GCSpause: {
- markroot(L); /* start a new collection */
- return 0;
+ /* start to count memory traversed */
+ g->GCmemtrav = g->strt.size * sizeof(GCObject*);
+ lua_assert(!isgenerational(g));
+ restartcollection(g);
+ g->gcstate = GCSpropagate;
+ return g->GCmemtrav;
}
case GCSpropagate: {
- if (g->gray)
- return propagatemark(g);
+ if (g->gray) {
+ lu_mem oldtrav = g->GCmemtrav;
+ propagatemark(g);
+ return g->GCmemtrav - oldtrav; /* memory traversed in this step */
+ }
else { /* no more `gray' objects */
- atomic(L); /* finish mark phase */
- return 0;
+ lu_mem work;
+ int sw;
+ g->gcstate = GCSatomic; /* finish mark phase */
+ g->GCestimate = g->GCmemtrav; /* save what was counted */;
+ work = atomic(L); /* add what was traversed by 'atomic' */
+ g->GCestimate += work; /* estimate of total memory traversed */
+ sw = entersweep(L);
+ return work + sw * GCSWEEPCOST;
}
}
case GCSsweepstring: {
- lu_mem old = g->totalbytes;
- 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;
+ int i;
+ for (i = 0; i < GCSWEEPMAX && g->sweepstrgc + i < g->strt.size; i++)
+ sweepwholelist(L, &g->strt.hash[g->sweepstrgc + i]);
+ g->sweepstrgc += i;
+ if (g->sweepstrgc >= g->strt.size) /* no more strings to sweep? */
+ g->gcstate = GCSsweepudata;
+ return i * 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);
- g->gcstate = GCSfinalize; /* end sweep phase */
- }
- lua_assert(old >= g->totalbytes);
- g->estimate -= old - g->totalbytes;
- return GCSWEEPMAX*GCSWEEPCOST;
- }
- case GCSfinalize: {
- if (g->tmudata) {
- GCTM(L);
- if (g->estimate > GCFINALIZECOST)
- g->estimate -= GCFINALIZECOST;
- return GCFINALIZECOST;
+ case GCSsweepudata: {
+ if (g->sweepfin) {
+ g->sweepfin = sweeplist(L, g->sweepfin, GCSWEEPMAX);
+ return GCSWEEPMAX*GCSWEEPCOST;
}
else {
- g->gcstate = GCSpause; /* end collection */
- g->gcdept = 0;
+ g->gcstate = GCSsweep;
return 0;
}
}
+ case GCSsweep: {
+ if (g->sweepgc) {
+ g->sweepgc = sweeplist(L, g->sweepgc, GCSWEEPMAX);
+ return GCSWEEPMAX*GCSWEEPCOST;
+ }
+ else {
+ /* sweep main thread */
+ GCObject *mt = obj2gco(g->mainthread);
+ sweeplist(L, &mt, 1);
+ checkSizes(L);
+ g->gcstate = GCSpause; /* finish collection */
+ return GCSWEEPCOST;
+ }
+ }
default: lua_assert(0); return 0;
}
}
-void luaC_step (lua_State *L) {
+/*
+** 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);
- l_mem lim = (GCSTEPSIZE/100) * g->gcstepmul;
- if (lim == 0)
- lim = (MAX_LUMEM-1)/2; /* no limit */
- g->gcdept += g->totalbytes - g->GCthreshold;
- do {
- lim -= singlestep(L);
- if (g->gcstate == GCSpause)
- break;
- } while (lim > 0);
- if (g->gcstate != GCSpause) {
- if (g->gcdept < GCSTEPSIZE)
- g->GCthreshold = g->totalbytes + GCSTEPSIZE; /* - lim/g->gcstepmul;*/
- else {
- g->gcdept -= GCSTEPSIZE;
- g->GCthreshold = g->totalbytes;
- }
- }
- else {
- lua_assert(g->totalbytes >= g->estimate);
- setthreshold(g);
- }
+ while (!testbit(statesmask, g->gcstate))
+ singlestep(L);
}
-void luaC_fullgc (lua_State *L) {
+static void generationalcollection (lua_State *L) {
global_State *g = G(L);
- if (g->gcstate <= GCSpropagate) {
- /* 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;
- }
- lua_assert(g->gcstate != GCSpause && g->gcstate != GCSpropagate);
- /* finish any pending sweep phase */
- while (g->gcstate != GCSfinalize) {
- lua_assert(g->gcstate == GCSsweepstring || g->gcstate == GCSsweep);
- singlestep(L);
+ lua_assert(g->gcstate == GCSpropagate);
+ if (g->GCestimate == 0) { /* signal for another major collection? */
+ luaC_fullgc(L, 0); /* perform a full regular collection */
+ g->GCestimate = gettotalbytes(g); /* update control */
}
- markroot(L);
- while (g->gcstate != GCSpause) {
- singlestep(L);
+ else {
+ lu_mem estimate = g->GCestimate;
+ luaC_runtilstate(L, bitmask(GCSpause)); /* run complete (minor) cycle */
+ g->gcstate = GCSpropagate; /* skip restart */
+ if (gettotalbytes(g) > (estimate / 100) * g->gcmajorinc)
+ g->GCestimate = 0; /* signal for a major collection */
+ else
+ g->GCestimate = estimate; /* keep estimate from last major coll. */
+
}
- setthreshold(g);
+ setpause(g, gettotalbytes(g));
+ lua_assert(g->gcstate == GCSpropagate);
}
-void luaC_barrierf (lua_State *L, GCObject *o, GCObject *v) {
+static void incstep (lua_State *L) {
global_State *g = G(L);
- lua_assert(isblack(o) && iswhite(v) && !isdead(g, v) && !isdead(g, o));
- lua_assert(g->gcstate != GCSfinalize && g->gcstate != GCSpause);
- lua_assert(ttype(&o->gch) != LUA_TTABLE);
- /* must keep invariant? */
- if (g->gcstate == GCSpropagate)
- reallymarkobject(g, v); /* restore invariant */
- else /* don't mind */
- makewhite(g, o); /* mark as white just to avoid other barriers */
+ l_mem debt = g->GCdebt;
+ int stepmul = g->gcstepmul;
+ if (stepmul < 40) stepmul = 40; /* avoid ridiculous low values (and 0) */
+ /* convert debt from Kb to 'work units' (avoid zero debt and overflows) */
+ debt = (debt / STEPMULADJ) + 1;
+ debt = (debt < MAX_LMEM / stepmul) ? debt * stepmul : MAX_LMEM;
+ do { /* always perform at least one single step */
+ lu_mem work = singlestep(L); /* do some work */
+ debt -= work;
+ } while (debt > -GCSTEPSIZE && g->gcstate != GCSpause);
+ if (g->gcstate == GCSpause)
+ setpause(g, g->GCestimate); /* pause until next cycle */
+ else {
+ debt = (debt / stepmul) * STEPMULADJ; /* convert 'work units' to Kb */
+ luaE_setdebt(g, debt);
+ }
}
-void luaC_barrierback (lua_State *L, Table *t) {
+/*
+** performs a basic GC step
+*/
+void luaC_forcestep (lua_State *L) {
global_State *g = G(L);
- GCObject *o = obj2gco(t);
- lua_assert(isblack(o) && !isdead(g, o));
- lua_assert(g->gcstate != GCSfinalize && g->gcstate != GCSpause);
- black2gray(o); /* make table gray (again) */
- t->gclist = g->grayagain;
- g->grayagain = o;
+ int i;
+ if (isgenerational(g)) generationalcollection(L);
+ else incstep(L);
+ /* run a few finalizers (or all of them at the end of a collect cycle) */
+ for (i = 0; g->tobefnz && (i < GCFINALIZENUM || g->gcstate == GCSpause); i++)
+ GCTM(L, 1); /* call one finalizer */
}
-void luaC_link (lua_State *L, GCObject *o, lu_byte tt) {
+/*
+** performs a basic GC step only if collector is running
+*/
+void luaC_step (lua_State *L) {
global_State *g = G(L);
- o->gch.next = g->rootgc;
- g->rootgc = o;
- o->gch.marked = luaC_white(g);
- o->gch.tt = tt;
+ if (g->gcrunning) luaC_forcestep(L);
+ else luaE_setdebt(g, -GCSTEPSIZE); /* avoid being called too often */
}
-void luaC_linkupval (lua_State *L, UpVal *uv) {
+
+/*
+** 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);
- GCObject *o = obj2gco(uv);
- o->gch.next = g->rootgc; /* link upvalue into `rootgc' list */
- g->rootgc = o;
- if (isgray(o)) {
- if (g->gcstate == GCSpropagate) {
- gray2black(o); /* closed upvalues need barrier */
- luaC_barrier(L, uv, uv->v);
- }
- else { /* sweep phase: sweep it (turning it into white) */
- makewhite(g, o);
- lua_assert(g->gcstate != GCSfinalize && g->gcstate != GCSpause);
- }
+ int origkind = g->gckind;
+ lua_assert(origkind != KGC_EMERGENCY);
+ if (isemergency) /* do not run finalizers during emergency GC */
+ g->gckind = KGC_EMERGENCY;
+ else {
+ g->gckind = KGC_NORMAL;
+ 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 */
+ if (origkind == KGC_GEN) { /* generational mode? */
+ /* generational mode must be kept in propagate phase */
+ luaC_runtilstate(L, bitmask(GCSpropagate));
}
+ g->gckind = origkind;
+ setpause(g, gettotalbytes(g));
+ if (!isemergency) /* do not run finalizers during emergency GC */
+ callallpendingfinalizers(L, 1);
}
+/* }====================================================== */
+
+