1218 lines
37 KiB
C
1218 lines
37 KiB
C
/* BEGIN CSTYLED */
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/*
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** $Id: lgc.c,v 2.140.1.3 2014/09/01 16:55:08 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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#define lgc_c
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#define LUA_CORE
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#include <sys/lua/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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/*
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** cost of sweeping one element (the size of a small object divided
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** by some adjust for the sweep speed)
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*/
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#define GCSWEEPCOST ((sizeof(TString) + 4) / 4)
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/* maximum number of elements to sweep in each single step */
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#define GCSWEEPMAX (cast_int((GCSTEPSIZE / GCSWEEPCOST) / 4))
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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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/*
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** macro to adjust 'stepmul': 'stepmul' is actually used like
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** 'stepmul / STEPMULADJ' (value chosen by tests)
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*/
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#define STEPMULADJ 200
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/*
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** macro to adjust 'pause': 'pause' is actually used like
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** 'pause / PAUSEADJ' (value chosen by tests)
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*/
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#define PAUSEADJ 100
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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 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 (global_State *g, const TValue *o) {
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if (!iscollectable(o)) return 0;
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else if (ttisstring(o)) {
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markobject(g, 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(g->gcstate != GCSpause);
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lua_assert(gch(o)->tt != LUA_TTABLE);
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if (keepinvariantout(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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char *raw = cast(char *, luaM_newobject(L, novariant(tt), sz));
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GCObject *o = obj2gco(raw + 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, strings, and closed upvalues are visited
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** and turned black here. Other objects are marked gray and added
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** to appropriate list to be visited (and turned black) later. (Open
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** upvalues are already linked in 'headuv' list.)
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*/
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static void reallymarkobject (global_State *g, GCObject *o) {
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lu_mem size;
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white2gray(o);
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switch (gch(o)->tt) {
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case LUA_TSHRSTR:
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case LUA_TLNGSTR: {
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size = sizestring(gco2ts(o));
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break; /* nothing else to mark; make it 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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size = sizeudata(gco2u(o));
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break;
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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) /* open? */
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return; /* open upvalues remain gray */
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size = sizeof(UpVal);
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break;
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}
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case LUA_TLCL: {
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gco2lcl(o)->gclist = g->gray;
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g->gray = o;
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return;
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}
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case LUA_TCCL: {
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gco2ccl(o)->gclist = g->gray;
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g->gray = o;
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return;
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}
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case LUA_TTABLE: {
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linktable(gco2t(o), &g->gray);
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return;
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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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return;
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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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return;
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}
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default: lua_assert(0); return;
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}
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gray2black(o);
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g->GCmemtrav += size;
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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 restartcollection (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(g, 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(g, 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 (g->gcstate != GCSatomic || 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 lu_mem traversetable (global_State *g, Table *h) {
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const char *weakkey, *weakvalue;
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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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((weakkey = strchr(svalue(mode), 'k')),
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(weakvalue = strchr(svalue(mode), 'v')),
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(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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else if (!weakvalue) /* strong values? */
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traverseephemeron(g, h);
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else /* all weak */
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linktable(h, &g->allweak); /* nothing to traverse now */
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}
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else /* not weak */
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traversestrongtable(g, h);
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return sizeof(Table) + sizeof(TValue) * h->sizearray +
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sizeof(Node) * cast(size_t, 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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markobject(g, 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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markobject(g, 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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markobject(g, f->locvars[i].varname);
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return sizeof(Proto) + sizeof(Instruction) * f->sizecode +
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sizeof(Proto *) * f->sizep +
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sizeof(TValue) * f->sizek +
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sizeof(int) * f->sizelineinfo +
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sizeof(LocVar) * f->sizelocvars +
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sizeof(Upvaldesc) * f->sizeupvalues;
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}
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static lu_mem traverseCclosure (global_State *g, CClosure *cl) {
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int i;
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for (i = 0; i < cl->nupvalues; i++) /* mark its upvalues */
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markvalue(g, &cl->upvalue[i]);
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return sizeCclosure(cl->nupvalues);
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}
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static lu_mem traverseLclosure (global_State *g, LClosure *cl) {
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int i;
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markobject(g, cl->p); /* mark its prototype */
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for (i = 0; i < cl->nupvalues; i++) /* mark its upvalues */
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markobject(g, cl->upvals[i]);
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return sizeLclosure(cl->nupvalues);
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}
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static lu_mem traversestack (global_State *g, lua_State *th) {
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int n = 0;
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StkId o = th->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 < th->top; o++) /* mark live elements in the stack */
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markvalue(g, o);
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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 (except for threads,
|
|
** which are always gray).
|
|
*/
|
|
static void propagatemark (global_State *g) {
|
|
lu_mem size;
|
|
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; /* 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; /* remove from 'gray' list */
|
|
th->gclist = g->grayagain;
|
|
g->grayagain = o; /* insert into 'grayagain' list */
|
|
black2gray(o);
|
|
size = traversestack(g, th);
|
|
break;
|
|
}
|
|
case LUA_TPROTO: {
|
|
Proto *p = gco2p(o);
|
|
g->gray = p->gclist; /* remove from 'gray' list */
|
|
size = traverseproto(g, p);
|
|
break;
|
|
}
|
|
default: lua_assert(0); return;
|
|
}
|
|
g->GCmemtrav += size;
|
|
}
|
|
|
|
|
|
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 (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 */
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
|
|
/*
|
|
** 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); /* 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_TLCL: {
|
|
luaM_freemem(L, o, sizeLclosure(gco2lcl(o)->nupvalues));
|
|
break;
|
|
}
|
|
case LUA_TCCL: {
|
|
luaM_freemem(L, o, sizeCclosure(gco2ccl(o)->nupvalues));
|
|
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_TSHRSTR:
|
|
G(L)->strt.nuse--;
|
|
/* FALLTHROUGH */
|
|
case LUA_TLNGSTR: {
|
|
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 */
|
|
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);
|
|
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 (!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);
|
|
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 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 */
|
|
}
|
|
}
|
|
}
|
|
|
|
|
|
/*
|
|
** 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 (!(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;
|
|
}
|
|
}
|
|
}
|
|
|
|
|
|
/*
|
|
** 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;
|
|
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 */
|
|
}
|
|
}
|
|
|
|
/* }====================================================== */
|
|
|
|
|
|
/*
|
|
** {======================================================
|
|
** 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);
|
|
}
|
|
|
|
|
|
#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);
|
|
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;
|
|
}
|
|
|
|
|
|
/*
|
|
** 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);
|
|
}
|
|
}
|
|
|
|
|
|
/*
|
|
** 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 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 */
|
|
/* 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 lu_mem singlestep (lua_State *L) {
|
|
global_State *g = G(L);
|
|
switch (g->gcstate) {
|
|
case GCSpause: {
|
|
/* 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) {
|
|
lu_mem oldtrav = g->GCmemtrav;
|
|
propagatemark(g);
|
|
return g->GCmemtrav - oldtrav; /* memory traversed in this step */
|
|
}
|
|
else { /* no more `gray' objects */
|
|
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: {
|
|
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 GCSsweepudata: {
|
|
if (g->sweepfin) {
|
|
g->sweepfin = sweeplist(L, g->sweepfin, GCSWEEPMAX);
|
|
return GCSWEEPMAX*GCSWEEPCOST;
|
|
}
|
|
else {
|
|
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;
|
|
}
|
|
}
|
|
|
|
|
|
/*
|
|
** 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);
|
|
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 */
|
|
}
|
|
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. */
|
|
|
|
}
|
|
setpause(g, gettotalbytes(g));
|
|
lua_assert(g->gcstate == GCSpropagate);
|
|
}
|
|
|
|
|
|
static void incstep (lua_State *L) {
|
|
global_State *g = G(L);
|
|
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);
|
|
}
|
|
}
|
|
|
|
|
|
/*
|
|
** performs a basic GC step
|
|
*/
|
|
void luaC_forcestep (lua_State *L) {
|
|
global_State *g = G(L);
|
|
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 */
|
|
}
|
|
|
|
|
|
/*
|
|
** performs a basic GC step only if collector is running
|
|
*/
|
|
void luaC_step (lua_State *L) {
|
|
global_State *g = G(L);
|
|
if (g->gcrunning) luaC_forcestep(L);
|
|
else luaE_setdebt(g, -GCSTEPSIZE); /* avoid being called too often */
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
** 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 */
|
|
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);
|
|
}
|
|
|
|
/* }====================================================== */
|
|
/* END CSTYLED */
|