forked from KolibriOS/kolibrios
1104 lines
33 KiB
C
1104 lines
33 KiB
C
/*
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** $Id: lgc.c,v 2.116 2011/12/02 13:18:41 roberto Exp $
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** Garbage Collector
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** See Copyright Notice in lua.h
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*/
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#include <string.h>
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#define lgc_c
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#define LUA_CORE
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#include "lua.h"
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#include "ldebug.h"
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#include "ldo.h"
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#include "lfunc.h"
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#include "lgc.h"
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#include "lmem.h"
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#include "lobject.h"
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#include "lstate.h"
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#include "lstring.h"
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#include "ltable.h"
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#include "ltm.h"
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/* how much to allocate before next GC step */
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#define GCSTEPSIZE 1024
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/* maximum number of elements to sweep in each single step */
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#define GCSWEEPMAX 40
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/* cost of sweeping one element */
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#define GCSWEEPCOST 1
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/* maximum number of finalizers to call in each GC step */
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#define GCFINALIZENUM 4
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/* cost of marking the root set */
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#define GCROOTCOST 10
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/* cost of atomic step */
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#define GCATOMICCOST 1000
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/* basic cost to traverse one object (to be added to the links the
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object may have) */
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#define TRAVCOST 5
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/*
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** standard negative debt for GC; a reasonable "time" to wait before
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** starting a new cycle
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*/
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#define stddebt(g) (-cast(l_mem, gettotalbytes(g)/100) * g->gcpause)
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/*
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** 'makewhite' erases all color bits plus the old bit and then
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** sets only the current white bit
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*/
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#define maskcolors (~(bit2mask(BLACKBIT, OLDBIT) | WHITEBITS))
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#define makewhite(g,x) \
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(gch(x)->marked = cast_byte((gch(x)->marked & maskcolors) | luaC_white(g)))
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#define white2gray(x) resetbits(gch(x)->marked, WHITEBITS)
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#define black2gray(x) resetbit(gch(x)->marked, BLACKBIT)
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#define stringmark(s) ((void)((s) && resetbits((s)->tsv.marked, WHITEBITS)))
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#define isfinalized(x) testbit(gch(x)->marked, FINALIZEDBIT)
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#define checkdeadkey(n) lua_assert(!ttisdeadkey(gkey(n)) || ttisnil(gval(n)))
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#define checkconsistency(obj) \
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lua_longassert(!iscollectable(obj) || righttt(obj))
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#define markvalue(g,o) { checkconsistency(o); \
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if (valiswhite(o)) reallymarkobject(g,gcvalue(o)); }
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#define markobject(g,t) { if ((t) && iswhite(obj2gco(t))) \
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reallymarkobject(g, obj2gco(t)); }
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static void reallymarkobject (global_State *g, GCObject *o);
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/*
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** {======================================================
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** Generic functions
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** =======================================================
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*/
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/*
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** one after last element in a hash array
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*/
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#define gnodelast(h) gnode(h, cast(size_t, sizenode(h)))
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/*
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** link table 'h' into list pointed by 'p'
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*/
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#define linktable(h,p) ((h)->gclist = *(p), *(p) = obj2gco(h))
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/*
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** if key is not marked, mark its entry as dead (therefore removing it
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** from the table)
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*/
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static void removeentry (Node *n) {
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lua_assert(ttisnil(gval(n)));
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if (valiswhite(gkey(n)))
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setdeadvalue(gkey(n)); /* unused and unmarked key; remove it */
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}
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/*
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** tells whether a key or value can be cleared from a weak
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** table. Non-collectable objects are never removed from weak
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** tables. Strings behave as `values', so are never removed too. for
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** other objects: if really collected, cannot keep them; for objects
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** being finalized, keep them in keys, but not in values
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*/
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static int iscleared (const TValue *o) {
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if (!iscollectable(o)) return 0;
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else if (ttisstring(o)) {
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stringmark(rawtsvalue(o)); /* strings are `values', so are never weak */
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return 0;
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}
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else return iswhite(gcvalue(o));
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}
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/*
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** barrier that moves collector forward, that is, mark the white object
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** being pointed by a black object.
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*/
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void luaC_barrier_ (lua_State *L, GCObject *o, GCObject *v) {
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global_State *g = G(L);
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lua_assert(isblack(o) && iswhite(v) && !isdead(g, v) && !isdead(g, o));
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lua_assert(isgenerational(g) || g->gcstate != GCSpause);
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lua_assert(gch(o)->tt != LUA_TTABLE);
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if (keepinvariant(g)) /* must keep invariant? */
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reallymarkobject(g, v); /* restore invariant */
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else { /* sweep phase */
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lua_assert(issweepphase(g));
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makewhite(g, o); /* mark main obj. as white to avoid other barriers */
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}
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}
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/*
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** barrier that moves collector backward, that is, mark the black object
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** pointing to a white object as gray again. (Current implementation
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** only works for tables; access to 'gclist' is not uniform across
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** different types.)
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*/
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void luaC_barrierback_ (lua_State *L, GCObject *o) {
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global_State *g = G(L);
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lua_assert(isblack(o) && !isdead(g, o) && gch(o)->tt == LUA_TTABLE);
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black2gray(o); /* make object gray (again) */
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gco2t(o)->gclist = g->grayagain;
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g->grayagain = o;
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}
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/*
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** barrier for prototypes. When creating first closure (cache is
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** NULL), use a forward barrier; this may be the only closure of the
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** prototype (if it is a "regular" function, with a single instance)
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** and the prototype may be big, so it is better to avoid traversing
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** it again. Otherwise, use a backward barrier, to avoid marking all
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** possible instances.
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*/
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LUAI_FUNC void luaC_barrierproto_ (lua_State *L, Proto *p, Closure *c) {
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global_State *g = G(L);
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lua_assert(isblack(obj2gco(p)));
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if (p->cache == NULL) { /* first time? */
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luaC_objbarrier(L, p, c);
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}
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else { /* use a backward barrier */
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black2gray(obj2gco(p)); /* make prototype gray (again) */
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p->gclist = g->grayagain;
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g->grayagain = obj2gco(p);
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}
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}
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/*
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** check color (and invariants) for an upvalue that was closed,
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** i.e., moved into the 'allgc' list
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*/
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void luaC_checkupvalcolor (global_State *g, UpVal *uv) {
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GCObject *o = obj2gco(uv);
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lua_assert(!isblack(o)); /* open upvalues are never black */
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if (isgray(o)) {
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if (keepinvariant(g)) {
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resetoldbit(o); /* see MOVE OLD rule */
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gray2black(o); /* it is being visited now */
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markvalue(g, uv->v);
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}
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else {
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lua_assert(issweepphase(g));
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makewhite(g, o);
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}
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}
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}
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/*
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** create a new collectable object (with given type and size) and link
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** it to '*list'. 'offset' tells how many bytes to allocate before the
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** object itself (used only by states).
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*/
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GCObject *luaC_newobj (lua_State *L, int tt, size_t sz, GCObject **list,
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int offset) {
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global_State *g = G(L);
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GCObject *o = obj2gco(cast(char *, luaM_newobject(L, tt, sz)) + offset);
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if (list == NULL)
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list = &g->allgc; /* standard list for collectable objects */
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gch(o)->marked = luaC_white(g);
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gch(o)->tt = tt;
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gch(o)->next = *list;
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*list = o;
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return o;
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}
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/* }====================================================== */
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/*
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** {======================================================
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** Mark functions
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** =======================================================
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*/
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/*
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** mark an object. Userdata and closed upvalues are visited and turned
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** black here. Strings remain gray (it is the same as making them
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** black). Other objects are marked gray and added to appropriate list
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** to be visited (and turned black) later. (Open upvalues are already
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** linked in 'headuv' list.)
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*/
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static void reallymarkobject (global_State *g, GCObject *o) {
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lua_assert(iswhite(o) && !isdead(g, o));
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white2gray(o);
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switch (gch(o)->tt) {
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case LUA_TSTRING: {
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return; /* for strings, gray is as good as black */
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}
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case LUA_TUSERDATA: {
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Table *mt = gco2u(o)->metatable;
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markobject(g, mt);
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markobject(g, gco2u(o)->env);
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gray2black(o); /* all pointers marked */
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return;
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}
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case LUA_TUPVAL: {
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UpVal *uv = gco2uv(o);
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markvalue(g, uv->v);
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if (uv->v == &uv->u.value) /* closed? (open upvalues remain gray) */
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gray2black(o); /* make it black */
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return;
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}
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case LUA_TFUNCTION: {
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gco2cl(o)->c.gclist = g->gray;
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g->gray = o;
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break;
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}
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case LUA_TTABLE: {
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linktable(gco2t(o), &g->gray);
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break;
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}
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case LUA_TTHREAD: {
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gco2th(o)->gclist = g->gray;
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g->gray = o;
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break;
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}
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case LUA_TPROTO: {
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gco2p(o)->gclist = g->gray;
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g->gray = o;
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break;
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}
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default: lua_assert(0);
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}
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}
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/*
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** mark metamethods for basic types
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*/
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static void markmt (global_State *g) {
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int i;
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for (i=0; i < LUA_NUMTAGS; i++)
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markobject(g, g->mt[i]);
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}
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/*
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** mark all objects in list of being-finalized
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*/
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static void markbeingfnz (global_State *g) {
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GCObject *o;
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for (o = g->tobefnz; o != NULL; o = gch(o)->next) {
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makewhite(g, o);
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reallymarkobject(g, o);
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}
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}
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/*
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** mark all values stored in marked open upvalues. (See comment in
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** 'lstate.h'.)
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*/
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static void remarkupvals (global_State *g) {
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UpVal *uv;
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for (uv = g->uvhead.u.l.next; uv != &g->uvhead; uv = uv->u.l.next) {
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if (isgray(obj2gco(uv)))
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markvalue(g, uv->v);
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}
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}
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/*
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** mark root set and reset all gray lists, to start a new
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** incremental (or full) collection
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*/
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static void markroot (global_State *g) {
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g->gray = g->grayagain = NULL;
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g->weak = g->allweak = g->ephemeron = NULL;
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markobject(g, g->mainthread);
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markvalue(g, &g->l_registry);
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markmt(g);
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markbeingfnz(g); /* mark any finalizing object left from previous cycle */
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}
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/* }====================================================== */
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/*
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** {======================================================
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** Traverse functions
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** =======================================================
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*/
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static void traverseweakvalue (global_State *g, Table *h) {
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Node *n, *limit = gnodelast(h);
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/* if there is array part, assume it may have white values (do not
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traverse it just to check) */
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int hasclears = (h->sizearray > 0);
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for (n = gnode(h, 0); n < limit; n++) {
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checkdeadkey(n);
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if (ttisnil(gval(n))) /* entry is empty? */
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removeentry(n); /* remove it */
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else {
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lua_assert(!ttisnil(gkey(n)));
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markvalue(g, gkey(n)); /* mark key */
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if (!hasclears && iscleared(gval(n))) /* is there a white value? */
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hasclears = 1; /* table will have to be cleared */
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}
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}
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if (hasclears)
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linktable(h, &g->weak); /* has to be cleared later */
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else /* no white values */
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linktable(h, &g->grayagain); /* no need to clean */
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}
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static int traverseephemeron (global_State *g, Table *h) {
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int marked = 0; /* true if an object is marked in this traversal */
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int hasclears = 0; /* true if table has white keys */
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int prop = 0; /* true if table has entry "white-key -> white-value" */
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Node *n, *limit = gnodelast(h);
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int i;
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/* traverse array part (numeric keys are 'strong') */
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for (i = 0; i < h->sizearray; i++) {
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if (valiswhite(&h->array[i])) {
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marked = 1;
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reallymarkobject(g, gcvalue(&h->array[i]));
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}
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}
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/* traverse hash part */
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for (n = gnode(h, 0); n < limit; n++) {
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checkdeadkey(n);
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if (ttisnil(gval(n))) /* entry is empty? */
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removeentry(n); /* remove it */
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else if (iscleared(gkey(n))) { /* key is not marked (yet)? */
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hasclears = 1; /* table must be cleared */
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if (valiswhite(gval(n))) /* value not marked yet? */
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prop = 1; /* must propagate again */
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}
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else if (valiswhite(gval(n))) { /* value not marked yet? */
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marked = 1;
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reallymarkobject(g, gcvalue(gval(n))); /* mark it now */
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}
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}
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if (prop)
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linktable(h, &g->ephemeron); /* have to propagate again */
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else if (hasclears) /* does table have white keys? */
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linktable(h, &g->allweak); /* may have to clean white keys */
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else /* no white keys */
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linktable(h, &g->grayagain); /* no need to clean */
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return marked;
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}
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static void traversestrongtable (global_State *g, Table *h) {
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Node *n, *limit = gnodelast(h);
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int i;
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for (i = 0; i < h->sizearray; i++) /* traverse array part */
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markvalue(g, &h->array[i]);
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for (n = gnode(h, 0); n < limit; n++) { /* traverse hash part */
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checkdeadkey(n);
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if (ttisnil(gval(n))) /* entry is empty? */
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removeentry(n); /* remove it */
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else {
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lua_assert(!ttisnil(gkey(n)));
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markvalue(g, gkey(n)); /* mark key */
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markvalue(g, gval(n)); /* mark value */
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}
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}
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}
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static int traversetable (global_State *g, Table *h) {
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const TValue *mode = gfasttm(g, h->metatable, TM_MODE);
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markobject(g, h->metatable);
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if (mode && ttisstring(mode)) { /* is there a weak mode? */
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int weakkey = (strchr(svalue(mode), 'k') != NULL);
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int weakvalue = (strchr(svalue(mode), 'v') != NULL);
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if (weakkey || weakvalue) { /* is really weak? */
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black2gray(obj2gco(h)); /* keep table gray */
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if (!weakkey) { /* strong keys? */
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traverseweakvalue(g, h);
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return TRAVCOST + sizenode(h);
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}
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else if (!weakvalue) { /* strong values? */
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traverseephemeron(g, h);
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return TRAVCOST + h->sizearray + sizenode(h);
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}
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else {
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linktable(h, &g->allweak); /* nothing to traverse now */
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return TRAVCOST;
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}
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} /* else go through */
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}
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traversestrongtable(g, h);
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return TRAVCOST + h->sizearray + (2 * sizenode(h));
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}
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static int traverseproto (global_State *g, Proto *f) {
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int i;
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if (f->cache && iswhite(obj2gco(f->cache)))
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f->cache = NULL; /* allow cache to be collected */
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stringmark(f->source);
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for (i = 0; i < f->sizek; i++) /* mark literals */
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markvalue(g, &f->k[i]);
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for (i = 0; i < f->sizeupvalues; i++) /* mark upvalue names */
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stringmark(f->upvalues[i].name);
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for (i = 0; i < f->sizep; i++) /* mark nested protos */
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markobject(g, f->p[i]);
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for (i = 0; i < f->sizelocvars; i++) /* mark local-variable names */
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stringmark(f->locvars[i].varname);
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return TRAVCOST + f->sizek + f->sizeupvalues + f->sizep + f->sizelocvars;
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}
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static int traverseclosure (global_State *g, Closure *cl) {
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if (cl->c.isC) {
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int i;
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for (i=0; i<cl->c.nupvalues; i++) /* mark its upvalues */
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markvalue(g, &cl->c.upvalue[i]);
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}
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else {
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int i;
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lua_assert(cl->l.nupvalues == cl->l.p->sizeupvalues);
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markobject(g, cl->l.p); /* mark its prototype */
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for (i=0; i<cl->l.nupvalues; i++) /* mark its upvalues */
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markobject(g, cl->l.upvals[i]);
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}
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return TRAVCOST + cl->c.nupvalues;
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}
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static int traversestack (global_State *g, lua_State *L) {
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StkId o = L->stack;
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if (o == NULL)
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return 1; /* stack not completely built yet */
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for (; o < L->top; o++)
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markvalue(g, o);
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if (g->gcstate == GCSatomic) { /* final traversal? */
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StkId lim = L->stack + L->stacksize; /* real end of stack */
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for (; o < lim; o++) /* clear not-marked stack slice */
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setnilvalue(o);
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}
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return TRAVCOST + cast_int(o - L->stack);
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}
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|
|
/*
|
|
** traverse one gray object, turning it to black (except for threads,
|
|
** which are always gray).
|
|
** Returns number of values traversed.
|
|
*/
|
|
static int propagatemark (global_State *g) {
|
|
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;
|
|
return traversetable(g, h);
|
|
}
|
|
case LUA_TFUNCTION: {
|
|
Closure *cl = gco2cl(o);
|
|
g->gray = cl->c.gclist;
|
|
return traverseclosure(g, cl);
|
|
}
|
|
case LUA_TTHREAD: {
|
|
lua_State *th = gco2th(o);
|
|
g->gray = th->gclist;
|
|
th->gclist = g->grayagain;
|
|
g->grayagain = o;
|
|
black2gray(o);
|
|
return traversestack(g, th);
|
|
}
|
|
case LUA_TPROTO: {
|
|
Proto *p = gco2p(o);
|
|
g->gray = p->gclist;
|
|
return traverseproto(g, p);
|
|
}
|
|
default: lua_assert(0); return 0;
|
|
}
|
|
}
|
|
|
|
|
|
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 (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(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 (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(o)) /* value was collected? */
|
|
setnilvalue(o); /* remove value */
|
|
}
|
|
for (n = gnode(h, 0); n < limit; n++) {
|
|
if (!ttisnil(gval(n)) && iscleared(gval(n))) {
|
|
setnilvalue(gval(n)); /* remove value ... */
|
|
removeentry(n); /* and remove entry from table */
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
|
|
static void freeobj (lua_State *L, GCObject *o) {
|
|
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, 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_TSTRING: {
|
|
G(L)->strt.nuse--;
|
|
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 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) {
|
|
global_State *g = G(L);
|
|
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 */
|
|
l_mem debt = g->GCdebt; /* current debt */
|
|
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 (gch(curr)->tt == LUA_TTHREAD)
|
|
sweepthread(L, gco2th(curr)); /* sweep thread's upvalues */
|
|
if (testbits(marked, tostop)) {
|
|
static GCObject *nullp = NULL;
|
|
p = &nullp; /* stop sweeping this list */
|
|
break;
|
|
}
|
|
/* update marks */
|
|
gch(curr)->marked = cast_byte((marked & toclear) | toset);
|
|
p = &gch(curr)->next; /* go to next element */
|
|
}
|
|
}
|
|
luaE_setdebt(g, debt); /* sweeping should not change debt */
|
|
return p;
|
|
}
|
|
|
|
/* }====================================================== */
|
|
|
|
|
|
/*
|
|
** {======================================================
|
|
** Finalization
|
|
** =======================================================
|
|
*/
|
|
|
|
static void checkSizes (lua_State *L) {
|
|
global_State *g = G(L);
|
|
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 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 (!keepinvariant(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);
|
|
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 msg.? */
|
|
luaO_pushfstring(L, "error in __gc metamethod (%s)",
|
|
lua_tostring(L, -1));
|
|
status = LUA_ERRGCMM; /* error in __gc metamethod */
|
|
}
|
|
luaD_throw(L, status); /* re-send error */
|
|
}
|
|
}
|
|
}
|
|
|
|
|
|
/*
|
|
** move all unreachable objects (or 'all' objects) that need
|
|
** finalization from list 'finobj' to list 'tobefnz' (to be finalized)
|
|
*/
|
|
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 (!(all || iswhite(curr))) /* 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;
|
|
}
|
|
}
|
|
}
|
|
|
|
|
|
/*
|
|
** 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 (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;
|
|
for (p = &g->allgc; *p != o; p = &gch(*p)->next) ;
|
|
*p = gch(o)->next; /* remove 'o' from root list */
|
|
gch(o)->next = g->finobj; /* link it in list 'finobj' */
|
|
g->finobj = o;
|
|
l_setbit(gch(o)->marked, SEPARATED); /* mark it as such */
|
|
resetoldbit(o); /* see MOVE OLD rule */
|
|
}
|
|
}
|
|
|
|
/* }====================================================== */
|
|
|
|
|
|
/*
|
|
** {======================================================
|
|
** GC control
|
|
** =======================================================
|
|
*/
|
|
|
|
|
|
#define sweepphases \
|
|
(bitmask(GCSsweepstring) | bitmask(GCSsweepudata) | bitmask(GCSsweep))
|
|
|
|
/*
|
|
** 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->lastmajormem = 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->sweepstrgc = 0;
|
|
g->gcstate = GCSsweepstring;
|
|
g->gckind = KGC_NORMAL;
|
|
luaC_runtilstate(L, ~sweepphases);
|
|
}
|
|
}
|
|
|
|
|
|
/*
|
|
** call all pending finalizers
|
|
*/
|
|
static void callallpendingfinalizers (lua_State *L, int propagateerrors) {
|
|
global_State *g = G(L);
|
|
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 void atomic (lua_State *L) {
|
|
global_State *g = G(L);
|
|
GCObject *origweak, *origall;
|
|
lua_assert(!iswhite(obj2gco(g->mainthread)));
|
|
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);
|
|
/* traverse objects caught by write barrier and by 'remarkupvals' */
|
|
retraversegrays(g);
|
|
convergeephemerons(g);
|
|
/* at this point, all strongly accessible objects are marked. */
|
|
/* clear values from weak tables, before checking finalizers */
|
|
clearvalues(g->weak, NULL);
|
|
clearvalues(g->allweak, NULL);
|
|
origweak = g->weak; origall = g->allweak;
|
|
separatetobefnz(L, 0); /* separate objects to be finalized */
|
|
markbeingfnz(g); /* mark userdata that will be finalized */
|
|
propagateall(g); /* remark, to propagate `preserveness' */
|
|
convergeephemerons(g);
|
|
/* at this point, all resurrected objects are marked. */
|
|
/* remove dead objects from weak tables */
|
|
clearkeys(g->ephemeron, NULL); /* clear keys from all ephemeron tables */
|
|
clearkeys(g->allweak, NULL); /* clear keys from all allweak tables */
|
|
/* clear values from resurrected weak tables */
|
|
clearvalues(g->weak, origweak);
|
|
clearvalues(g->allweak, origall);
|
|
g->sweepstrgc = 0; /* prepare to sweep strings */
|
|
g->gcstate = GCSsweepstring;
|
|
g->currentwhite = cast_byte(otherwhite(g)); /* flip current white */
|
|
/*lua_checkmemory(L);*/
|
|
}
|
|
|
|
|
|
static l_mem singlestep (lua_State *L) {
|
|
global_State *g = G(L);
|
|
switch (g->gcstate) {
|
|
case GCSpause: {
|
|
if (!isgenerational(g))
|
|
markroot(g); /* start a new collection */
|
|
/* in any case, root must be marked */
|
|
lua_assert(!iswhite(obj2gco(g->mainthread))
|
|
&& !iswhite(gcvalue(&g->l_registry)));
|
|
g->gcstate = GCSpropagate;
|
|
return GCROOTCOST;
|
|
}
|
|
case GCSpropagate: {
|
|
if (g->gray)
|
|
return propagatemark(g);
|
|
else { /* no more `gray' objects */
|
|
g->gcstate = GCSatomic; /* finish mark phase */
|
|
atomic(L);
|
|
return GCATOMICCOST;
|
|
}
|
|
}
|
|
case GCSsweepstring: {
|
|
if (g->sweepstrgc < g->strt.size) {
|
|
sweepwholelist(L, &g->strt.hash[g->sweepstrgc++]);
|
|
return GCSWEEPCOST;
|
|
}
|
|
else { /* no more strings to sweep */
|
|
g->sweepgc = &g->finobj; /* prepare to sweep finalizable objects */
|
|
g->gcstate = GCSsweepudata;
|
|
return 0;
|
|
}
|
|
}
|
|
case GCSsweepudata: {
|
|
if (*g->sweepgc) {
|
|
g->sweepgc = sweeplist(L, g->sweepgc, GCSWEEPMAX);
|
|
return GCSWEEPMAX*GCSWEEPCOST;
|
|
}
|
|
else {
|
|
g->sweepgc = &g->allgc; /* go to next phase */
|
|
g->gcstate = GCSsweep;
|
|
return GCSWEEPCOST;
|
|
}
|
|
}
|
|
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;
|
|
}
|
|
}
|
|
|
|
|
|
/*
|
|
** 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);
|
|
}
|
|
|
|
|
|
static void generationalcollection (lua_State *L) {
|
|
global_State *g = G(L);
|
|
if (g->lastmajormem == 0) { /* signal for another major collection? */
|
|
luaC_fullgc(L, 0); /* perform a full regular collection */
|
|
g->lastmajormem = gettotalbytes(g); /* update control */
|
|
}
|
|
else {
|
|
luaC_runtilstate(L, ~bitmask(GCSpause)); /* run complete cycle */
|
|
luaC_runtilstate(L, bitmask(GCSpause));
|
|
if (gettotalbytes(g) > g->lastmajormem/100 * g->gcmajorinc)
|
|
g->lastmajormem = 0; /* signal for a major collection */
|
|
}
|
|
luaE_setdebt(g, stddebt(g));
|
|
}
|
|
|
|
|
|
static void step (lua_State *L) {
|
|
global_State *g = G(L);
|
|
l_mem lim = g->gcstepmul; /* how much to work */
|
|
do { /* always perform at least one single step */
|
|
lim -= singlestep(L);
|
|
} while (lim > 0 && g->gcstate != GCSpause);
|
|
if (g->gcstate != GCSpause)
|
|
luaE_setdebt(g, g->GCdebt - GCSTEPSIZE);
|
|
else
|
|
luaE_setdebt(g, stddebt(g));
|
|
}
|
|
|
|
|
|
/*
|
|
** performs a basic GC step even if the collector is stopped
|
|
*/
|
|
void luaC_forcestep (lua_State *L) {
|
|
global_State *g = G(L);
|
|
int i;
|
|
if (isgenerational(g)) generationalcollection(L);
|
|
else step(L);
|
|
for (i = 0; i < GCFINALIZENUM && g->tobefnz; i++)
|
|
GCTM(L, 1); /* Call a few pending finalizers */
|
|
}
|
|
|
|
|
|
/*
|
|
** performs a basic GC step only if collector is running
|
|
*/
|
|
void luaC_step (lua_State *L) {
|
|
if (G(L)->gcrunning) luaC_forcestep(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);
|
|
int origkind = g->gckind;
|
|
lua_assert(origkind != KGC_EMERGENCY);
|
|
if (!isemergency) /* do not run finalizers during emergency GC */
|
|
callallpendingfinalizers(L, 1);
|
|
if (keepinvariant(g)) { /* marking phase? */
|
|
/* must sweep all objects to turn them back to white
|
|
(as white has not changed, nothing will be collected) */
|
|
g->sweepstrgc = 0;
|
|
g->gcstate = GCSsweepstring;
|
|
}
|
|
g->gckind = isemergency ? KGC_EMERGENCY : KGC_NORMAL;
|
|
/* finish any pending sweep phase to start a new cycle */
|
|
luaC_runtilstate(L, bitmask(GCSpause));
|
|
/* run entire collector */
|
|
luaC_runtilstate(L, ~bitmask(GCSpause));
|
|
luaC_runtilstate(L, bitmask(GCSpause));
|
|
if (origkind == KGC_GEN) { /* generational mode? */
|
|
/* generational mode must always start in propagate phase */
|
|
luaC_runtilstate(L, bitmask(GCSpropagate));
|
|
}
|
|
g->gckind = origkind;
|
|
luaE_setdebt(g, stddebt(g));
|
|
if (!isemergency) /* do not run finalizers during emergency GC */
|
|
callallpendingfinalizers(L, 1);
|
|
}
|
|
|
|
/* }====================================================== */
|
|
|
|
|