1/* 2** $Id: lgc.h,v 2.58 2012/09/11 12:53:08 roberto Exp $ 3** Garbage Collector 4** See Copyright Notice in lua.h 5*/ 6 7#ifndef lgc_h 8#define lgc_h 9 10 11#include "lobject.h" 12#include "lstate.h" 13 14/* 15** Collectable objects may have one of three colors: white, which 16** means the object is not marked; gray, which means the 17** object is marked, but its references may be not marked; and 18** black, which means that the object and all its references are marked. 19** The main invariant of the garbage collector, while marking objects, 20** is that a black object can never point to a white one. Moreover, 21** any gray object must be in a "gray list" (gray, grayagain, weak, 22** allweak, ephemeron) so that it can be visited again before finishing 23** the collection cycle. These lists have no meaning when the invariant 24** is not being enforced (e.g., sweep phase). 25*/ 26 27 28 29/* how much to allocate before next GC step */ 30#if !defined(GCSTEPSIZE) 31/* ~100 small strings */ 32#define GCSTEPSIZE (cast_int(100 * sizeof(TString))) 33#endif 34 35 36/* 37** Possible states of the Garbage Collector 38*/ 39#define GCSpropagate 0 40#define GCSatomic 1 41#define GCSsweepstring 2 42#define GCSsweepudata 3 43#define GCSsweep 4 44#define GCSpause 5 45 46 47#define issweepphase(g) \ 48 (GCSsweepstring <= (g)->gcstate && (g)->gcstate <= GCSsweep) 49 50#define isgenerational(g) ((g)->gckind == KGC_GEN) 51 52/* 53** macros to tell when main invariant (white objects cannot point to black 54** ones) must be kept. During a non-generational collection, the sweep 55** phase may break the invariant, as objects turned white may point to 56** still-black objects. The invariant is restored when sweep ends and 57** all objects are white again. During a generational collection, the 58** invariant must be kept all times. 59*/ 60 61#define keepinvariant(g) (isgenerational(g) || g->gcstate <= GCSatomic) 62 63 64/* 65** Outside the collector, the state in generational mode is kept in 66** 'propagate', so 'keepinvariant' is always true. 67*/ 68#define keepinvariantout(g) \ 69 check_exp(g->gcstate == GCSpropagate || !isgenerational(g), \ 70 g->gcstate <= GCSatomic) 71 72 73/* 74** some useful bit tricks 75*/ 76#define resetbits(x,m) ((x) &= cast(lu_byte, ~(m))) 77#define setbits(x,m) ((x) |= (m)) 78#define testbits(x,m) ((x) & (m)) 79#define bitmask(b) (1<<(b)) 80#define bit2mask(b1,b2) (bitmask(b1) | bitmask(b2)) 81#define l_setbit(x,b) setbits(x, bitmask(b)) 82#define resetbit(x,b) resetbits(x, bitmask(b)) 83#define testbit(x,b) testbits(x, bitmask(b)) 84 85 86/* Layout for bit use in `marked' field: */ 87#define WHITE0BIT 0 /* object is white (type 0) */ 88#define WHITE1BIT 1 /* object is white (type 1) */ 89#define BLACKBIT 2 /* object is black */ 90#define FINALIZEDBIT 3 /* object has been separated for finalization */ 91#define SEPARATED 4 /* object is in 'finobj' list or in 'tobefnz' */ 92#define FIXEDBIT 5 /* object is fixed (should not be collected) */ 93#define OLDBIT 6 /* object is old (only in generational mode) */ 94/* bit 7 is currently used by tests (luaL_checkmemory) */ 95 96#define WHITEBITS bit2mask(WHITE0BIT, WHITE1BIT) 97 98 99#define iswhite(x) testbits((x)->gch.marked, WHITEBITS) 100#define isblack(x) testbit((x)->gch.marked, BLACKBIT) 101#define isgray(x) /* neither white nor black */ \ 102 (!testbits((x)->gch.marked, WHITEBITS | bitmask(BLACKBIT))) 103 104#define isold(x) testbit((x)->gch.marked, OLDBIT) 105 106/* MOVE OLD rule: whenever an object is moved to the beginning of 107 a GC list, its old bit must be cleared */ 108#define resetoldbit(o) resetbit((o)->gch.marked, OLDBIT) 109 110#define otherwhite(g) (g->currentwhite ^ WHITEBITS) 111#define isdeadm(ow,m) (!(((m) ^ WHITEBITS) & (ow))) 112#define isdead(g,v) isdeadm(otherwhite(g), (v)->gch.marked) 113 114#define changewhite(x) ((x)->gch.marked ^= WHITEBITS) 115#define gray2black(x) l_setbit((x)->gch.marked, BLACKBIT) 116 117#define valiswhite(x) (iscollectable(x) && iswhite(gcvalue(x))) 118 119#define luaC_white(g) cast(lu_byte, (g)->currentwhite & WHITEBITS) 120 121 122#define luaC_condGC(L,c) \ 123 {if (G(L)->GCdebt > 0) {c;}; condchangemem(L);} 124#define luaC_checkGC(L) luaC_condGC(L, luaC_step(L);) 125 126 127#define luaC_barrier(L,p,v) { if (valiswhite(v) && isblack(obj2gco(p))) \ 128 luaC_barrier_(L,obj2gco(p),gcvalue(v)); } 129 130#define luaC_barrierback(L,p,v) { if (valiswhite(v) && isblack(obj2gco(p))) \ 131 luaC_barrierback_(L,p); } 132 133#define luaC_objbarrier(L,p,o) \ 134 { if (iswhite(obj2gco(o)) && isblack(obj2gco(p))) \ 135 luaC_barrier_(L,obj2gco(p),obj2gco(o)); } 136 137#define luaC_objbarrierback(L,p,o) \ 138 { if (iswhite(obj2gco(o)) && isblack(obj2gco(p))) luaC_barrierback_(L,p); } 139 140#define luaC_barrierproto(L,p,c) \ 141 { if (isblack(obj2gco(p))) luaC_barrierproto_(L,p,c); } 142 143LUAI_FUNC void luaC_freeallobjects (lua_State *L); 144LUAI_FUNC void luaC_step (lua_State *L); 145LUAI_FUNC void luaC_forcestep (lua_State *L); 146LUAI_FUNC void luaC_runtilstate (lua_State *L, int statesmask); 147LUAI_FUNC void luaC_fullgc (lua_State *L, int isemergency); 148LUAI_FUNC GCObject *luaC_newobj (lua_State *L, int tt, size_t sz, 149 GCObject **list, int offset); 150LUAI_FUNC void luaC_barrier_ (lua_State *L, GCObject *o, GCObject *v); 151LUAI_FUNC void luaC_barrierback_ (lua_State *L, GCObject *o); 152LUAI_FUNC void luaC_barrierproto_ (lua_State *L, Proto *p, Closure *c); 153LUAI_FUNC void luaC_checkfinalizer (lua_State *L, GCObject *o, Table *mt); 154LUAI_FUNC void luaC_checkupvalcolor (global_State *g, UpVal *uv); 155LUAI_FUNC void luaC_changemode (lua_State *L, int mode); 156 157#endif 158