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147 lines
4.6 KiB
147 lines
4.6 KiB
/* |
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** $Id: lgc.h,v 2.91.1.1 2017/04/19 17:39:34 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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#ifndef lgc_h |
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#define lgc_h |
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#include "lobject.h" |
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#include "lstate.h" |
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/* |
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** Collectable objects may have one of three colors: white, which |
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** means the object is not marked; gray, which means the |
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** object is marked, but its references may be not marked; and |
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** black, which means that the object and all its references are marked. |
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** The main invariant of the garbage collector, while marking objects, |
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** is that a black object can never point to a white one. Moreover, |
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** any gray object must be in a "gray list" (gray, grayagain, weak, |
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** allweak, ephemeron) so that it can be visited again before finishing |
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** the collection cycle. These lists have no meaning when the invariant |
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** is not being enforced (e.g., sweep phase). |
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*/ |
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/* how much to allocate before next GC step */ |
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#if !defined(GCSTEPSIZE) |
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/* ~100 small strings */ |
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#define GCSTEPSIZE (cast_int(100 * sizeof(TString))) |
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#endif |
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/* |
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** Possible states of the Garbage Collector |
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*/ |
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#define GCSpropagate 0 |
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#define GCSatomic 1 |
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#define GCSswpallgc 2 |
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#define GCSswpfinobj 3 |
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#define GCSswptobefnz 4 |
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#define GCSswpend 5 |
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#define GCScallfin 6 |
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#define GCSpause 7 |
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#define issweepphase(g) \ |
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(GCSswpallgc <= (g)->gcstate && (g)->gcstate <= GCSswpend) |
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/* |
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** macro to tell when main invariant (white objects cannot point to black |
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** ones) must be kept. During a collection, the sweep |
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** phase may break the invariant, as objects turned white may point to |
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** still-black objects. The invariant is restored when sweep ends and |
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** all objects are white again. |
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*/ |
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#define keepinvariant(g) ((g)->gcstate <= GCSatomic) |
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/* |
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** some useful bit tricks |
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*/ |
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#define resetbits(x,m) ((x) &= cast(lu_byte, ~(m))) |
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#define setbits(x,m) ((x) |= (m)) |
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#define testbits(x,m) ((x) & (m)) |
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#define bitmask(b) (1<<(b)) |
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#define bit2mask(b1,b2) (bitmask(b1) | bitmask(b2)) |
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#define l_setbit(x,b) setbits(x, bitmask(b)) |
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#define resetbit(x,b) resetbits(x, bitmask(b)) |
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#define testbit(x,b) testbits(x, bitmask(b)) |
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/* Layout for bit use in 'marked' field: */ |
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#define WHITE0BIT 0 /* object is white (type 0) */ |
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#define WHITE1BIT 1 /* object is white (type 1) */ |
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#define BLACKBIT 2 /* object is black */ |
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#define FINALIZEDBIT 3 /* object has been marked for finalization */ |
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/* bit 7 is currently used by tests (luaL_checkmemory) */ |
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#define WHITEBITS bit2mask(WHITE0BIT, WHITE1BIT) |
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#define iswhite(x) testbits((x)->marked, WHITEBITS) |
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#define isblack(x) testbit((x)->marked, BLACKBIT) |
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#define isgray(x) /* neither white nor black */ \ |
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(!testbits((x)->marked, WHITEBITS | bitmask(BLACKBIT))) |
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#define tofinalize(x) testbit((x)->marked, FINALIZEDBIT) |
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#define otherwhite(g) ((g)->currentwhite ^ WHITEBITS) |
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#define isdeadm(ow,m) (!(((m) ^ WHITEBITS) & (ow))) |
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#define isdead(g,v) isdeadm(otherwhite(g), (v)->marked) |
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#define changewhite(x) ((x)->marked ^= WHITEBITS) |
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#define gray2black(x) l_setbit((x)->marked, BLACKBIT) |
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#define luaC_white(g) cast(lu_byte, (g)->currentwhite & WHITEBITS) |
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/* |
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** Does one step of collection when debt becomes positive. 'pre'/'pos' |
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** allows some adjustments to be done only when needed. macro |
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** 'condchangemem' is used only for heavy tests (forcing a full |
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** GC cycle on every opportunity) |
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*/ |
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#define luaC_condGC(L,pre,pos) \ |
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{ if (G(L)->GCdebt > 0) { pre; luaC_step(L); pos;}; \ |
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condchangemem(L,pre,pos); } |
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/* more often than not, 'pre'/'pos' are empty */ |
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#define luaC_checkGC(L) luaC_condGC(L,(void)0,(void)0) |
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#define luaC_barrier(L,p,v) ( \ |
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(iscollectable(v) && isblack(p) && iswhite(gcvalue(v))) ? \ |
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luaC_barrier_(L,obj2gco(p),gcvalue(v)) : cast_void(0)) |
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#define luaC_barrierback(L,p,v) ( \ |
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(iscollectable(v) && isblack(p) && iswhite(gcvalue(v))) ? \ |
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luaC_barrierback_(L,p) : cast_void(0)) |
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#define luaC_objbarrier(L,p,o) ( \ |
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(isblack(p) && iswhite(o)) ? \ |
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luaC_barrier_(L,obj2gco(p),obj2gco(o)) : cast_void(0)) |
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#define luaC_upvalbarrier(L,uv) ( \ |
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(iscollectable((uv)->v) && !upisopen(uv)) ? \ |
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luaC_upvalbarrier_(L,uv) : cast_void(0)) |
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LUAI_FUNC void luaC_fix (lua_State *L, GCObject *o); |
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LUAI_FUNC void luaC_freeallobjects (lua_State *L); |
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LUAI_FUNC void luaC_step (lua_State *L); |
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LUAI_FUNC void luaC_runtilstate (lua_State *L, int statesmask); |
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LUAI_FUNC void luaC_fullgc (lua_State *L, int isemergency); |
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LUAI_FUNC GCObject *luaC_newobj (lua_State *L, int tt, size_t sz); |
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LUAI_FUNC void luaC_barrier_ (lua_State *L, GCObject *o, GCObject *v); |
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LUAI_FUNC void luaC_barrierback_ (lua_State *L, Table *o); |
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LUAI_FUNC void luaC_upvalbarrier_ (lua_State *L, UpVal *uv); |
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LUAI_FUNC void luaC_checkfinalizer (lua_State *L, GCObject *o, Table *mt); |
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LUAI_FUNC void luaC_upvdeccount (lua_State *L, UpVal *uv); |
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#endif
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