mirror of
https://github.com/lua/lua
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142 lines
5.0 KiB
C
142 lines
5.0 KiB
C
/*
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** $Id: lgc.h,v 2.52 2011/10/03 17:54:25 roberto Exp roberto $
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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 rule does not apply to strings,
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** which are never black but do not need to be visited again.)
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** These lists have no meaning when the invariant is not being enforced
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** (e.g., sweep phase).
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*/
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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 GCSsweepstring 2
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#define GCSsweepudata 3
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#define GCSsweep 4
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#define GCSpause 5
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#define issweepphase(g) \
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(GCSsweepstring <= (g)->gcstate && (g)->gcstate <= GCSsweep)
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#define isgenerational(g) ((g)->gckind == KGC_GEN)
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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 non-generational 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. During a generational collection, the
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** invariant must be kept all times.
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*/
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#define keepinvariant(g) (isgenerational(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 separated for finalization */
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#define SEPARATED 4 /* object is in 'finobj' list or in 'tobefnz' */
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#define FIXEDBIT 5 /* object is fixed (should not be collected) */
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#define OLDBIT 6 /* object is old (only in generational mode) */
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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)->gch.marked, WHITEBITS)
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#define isblack(x) testbit((x)->gch.marked, BLACKBIT)
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#define isgray(x) /* neither white nor black */ \
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(!testbits((x)->gch.marked, WHITEBITS | bitmask(BLACKBIT)))
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#define isold(x) testbit((x)->gch.marked, OLDBIT)
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/* MOVE OLD rule: whenever an object is moved to the beginning of
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a GC list, its old bit must be cleared */
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#define resetoldbit(o) resetbit((o)->gch.marked, OLDBIT)
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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)->gch.marked)
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#define changewhite(x) ((x)->gch.marked ^= WHITEBITS)
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#define gray2black(x) l_setbit((x)->gch.marked, BLACKBIT)
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#define valiswhite(x) (iscollectable(x) && iswhite(gcvalue(x)))
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#define luaC_white(g) cast(lu_byte, (g)->currentwhite & WHITEBITS)
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#define luaC_condGC(L,c) \
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{if (G(L)->GCdebt > 0) {c;}; condchangemem(L);}
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#define luaC_checkGC(L) luaC_condGC(L, luaC_step(L);)
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#define luaC_barrier(L,p,v) { if (valiswhite(v) && isblack(obj2gco(p))) \
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luaC_barrier_(L,obj2gco(p),gcvalue(v)); }
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#define luaC_barrierback(L,p,v) { if (valiswhite(v) && isblack(obj2gco(p))) \
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luaC_barrierback_(L,p); }
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#define luaC_objbarrier(L,p,o) \
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{ if (iswhite(obj2gco(o)) && isblack(obj2gco(p))) \
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luaC_barrier_(L,obj2gco(p),obj2gco(o)); }
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#define luaC_objbarrierback(L,p,o) \
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{ if (iswhite(obj2gco(o)) && isblack(obj2gco(p))) luaC_barrierback_(L,p); }
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#define luaC_barrierproto(L,p,c) \
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{ if (isblack(obj2gco(p))) luaC_barrierproto_(L,p,c); }
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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_forcestep (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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GCObject **list, int offset);
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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, GCObject *o);
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LUAI_FUNC void luaC_barrierproto_ (lua_State *L, Proto *p, Closure *c);
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LUAI_FUNC void luaC_checkfinalizer (lua_State *L, GCObject *o, Table *mt);
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LUAI_FUNC void luaC_checkupvalcolor (global_State *g, UpVal *uv);
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LUAI_FUNC void luaC_changemode (lua_State *L, int mode);
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#endif
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