1 /* BEGIN CSTYLED */ 2 /* 3 ** $Id: lgc.h,v 2.58.1.1 2013/04/12 18:48:47 roberto Exp $ 4 ** Garbage Collector 5 ** See Copyright Notice in lua.h 6 */ 7 8 #ifndef lgc_h 9 #define lgc_h 10 11 12 #include "lobject.h" 13 #include "lstate.h" 14 15 /* 16 ** Collectable objects may have one of three colors: white, which 17 ** means the object is not marked; gray, which means the 18 ** object is marked, but its references may be not marked; and 19 ** black, which means that the object and all its references are marked. 20 ** The main invariant of the garbage collector, while marking objects, 21 ** is that a black object can never point to a white one. Moreover, 22 ** any gray object must be in a "gray list" (gray, grayagain, weak, 23 ** allweak, ephemeron) so that it can be visited again before finishing 24 ** the collection cycle. These lists have no meaning when the invariant 25 ** is not being enforced (e.g., sweep phase). 26 */ 27 28 29 30 /* how much to allocate before next GC step */ 31 #if !defined(GCSTEPSIZE) 32 /* ~100 small strings */ 33 #define GCSTEPSIZE (cast_int(100 * sizeof(TString))) 34 #endif 35 36 37 /* 38 ** Possible states of the Garbage Collector 39 */ 40 #define GCSpropagate 0 41 #define GCSatomic 1 42 #define GCSsweepstring 2 43 #define GCSsweepudata 3 44 #define GCSsweep 4 45 #define GCSpause 5 46 47 48 #define issweepphase(g) \ 49 (GCSsweepstring <= (g)->gcstate && (g)->gcstate <= GCSsweep) 50 51 #define isgenerational(g) ((g)->gckind == KGC_GEN) 52 53 /* 54 ** macros to tell when main invariant (white objects cannot point to black 55 ** ones) must be kept. During a non-generational collection, the sweep 56 ** phase may break the invariant, as objects turned white may point to 57 ** still-black objects. The invariant is restored when sweep ends and 58 ** all objects are white again. During a generational collection, the 59 ** invariant must be kept all times. 60 */ 61 62 #define keepinvariant(g) (isgenerational(g) || g->gcstate <= GCSatomic) 63 64 65 /* 66 ** Outside the collector, the state in generational mode is kept in 67 ** 'propagate', so 'keepinvariant' is always true. 68 */ 69 #define keepinvariantout(g) \ 70 check_exp(g->gcstate == GCSpropagate || !isgenerational(g), \ 71 g->gcstate <= GCSatomic) 72 73 74 /* 75 ** some useful bit tricks 76 */ 77 #define resetbits(x,m) ((x) &= cast(lu_byte, ~(m))) 78 #define setbits(x,m) ((x) |= (m)) 79 #define testbits(x,m) ((x) & (m)) 80 #define bitmask(b) (1<<(b)) 81 #define bit2mask(b1,b2) (bitmask(b1) | bitmask(b2)) 82 #define l_setbit(x,b) setbits(x, bitmask(b)) 83 #define resetbit(x,b) resetbits(x, bitmask(b)) 84 #define testbit(x,b) testbits(x, bitmask(b)) 85 86 87 /* Layout for bit use in `marked' field: */ 88 #define WHITE0BIT 0 /* object is white (type 0) */ 89 #define WHITE1BIT 1 /* object is white (type 1) */ 90 #define BLACKBIT 2 /* object is black */ 91 #define FINALIZEDBIT 3 /* object has been separated for finalization */ 92 #define SEPARATED 4 /* object is in 'finobj' list or in 'tobefnz' */ 93 #define FIXEDBIT 5 /* object is fixed (should not be collected) */ 94 #define OLDBIT 6 /* object is old (only in generational mode) */ 95 /* bit 7 is currently used by tests (luaL_checkmemory) */ 96 97 #define WHITEBITS bit2mask(WHITE0BIT, WHITE1BIT) 98 99 100 #define iswhite(x) testbits((x)->gch.marked, WHITEBITS) 101 #define isblack(x) testbit((x)->gch.marked, BLACKBIT) 102 #define isgray(x) /* neither white nor black */ \ 103 (!testbits((x)->gch.marked, WHITEBITS | bitmask(BLACKBIT))) 104 105 #define isold(x) testbit((x)->gch.marked, OLDBIT) 106 107 /* MOVE OLD rule: whenever an object is moved to the beginning of 108 a GC list, its old bit must be cleared */ 109 #define resetoldbit(o) resetbit((o)->gch.marked, OLDBIT) 110 111 #define otherwhite(g) (g->currentwhite ^ WHITEBITS) 112 #define isdeadm(ow,m) (!(((m) ^ WHITEBITS) & (ow))) 113 #define isdead(g,v) isdeadm(otherwhite(g), (v)->gch.marked) 114 115 #define changewhite(x) ((x)->gch.marked ^= WHITEBITS) 116 #define gray2black(x) l_setbit((x)->gch.marked, BLACKBIT) 117 118 #define valiswhite(x) (iscollectable(x) && iswhite(gcvalue(x))) 119 120 #define luaC_white(g) cast(lu_byte, (g)->currentwhite & WHITEBITS) 121 122 123 #define luaC_condGC(L,c) \ 124 {if (G(L)->GCdebt > 0) {c;}; condchangemem(L);} 125 #define luaC_checkGC(L) luaC_condGC(L, luaC_step(L);) 126 127 128 #define luaC_barrier(L,p,v) { if (valiswhite(v) && isblack(obj2gco(p))) \ 129 luaC_barrier_(L,obj2gco(p),gcvalue(v)); } 130 131 #define luaC_barrierback(L,p,v) { if (valiswhite(v) && isblack(obj2gco(p))) \ 132 luaC_barrierback_(L,p); } 133 134 #define luaC_objbarrier(L,p,o) \ 135 { if (iswhite(obj2gco(o)) && isblack(obj2gco(p))) \ 136 luaC_barrier_(L,obj2gco(p),obj2gco(o)); } 137 138 #define luaC_objbarrierback(L,p,o) \ 139 { if (iswhite(obj2gco(o)) && isblack(obj2gco(p))) luaC_barrierback_(L,p); } 140 141 #define luaC_barrierproto(L,p,c) \ 142 { if (isblack(obj2gco(p))) luaC_barrierproto_(L,p,c); } 143 144 LUAI_FUNC void luaC_freeallobjects (lua_State *L); 145 LUAI_FUNC void luaC_step (lua_State *L); 146 LUAI_FUNC void luaC_forcestep (lua_State *L); 147 LUAI_FUNC void luaC_runtilstate (lua_State *L, int statesmask); 148 LUAI_FUNC void luaC_fullgc (lua_State *L, int isemergency); 149 LUAI_FUNC GCObject *luaC_newobj (lua_State *L, int tt, size_t sz, 150 GCObject **list, int offset); 151 LUAI_FUNC void luaC_barrier_ (lua_State *L, GCObject *o, GCObject *v); 152 LUAI_FUNC void luaC_barrierback_ (lua_State *L, GCObject *o); 153 LUAI_FUNC void luaC_barrierproto_ (lua_State *L, Proto *p, Closure *c); 154 LUAI_FUNC void luaC_checkfinalizer (lua_State *L, GCObject *o, Table *mt); 155 LUAI_FUNC void luaC_checkupvalcolor (global_State *g, UpVal *uv); 156 LUAI_FUNC void luaC_changemode (lua_State *L, int mode); 157 158 #endif 159 /* END CSTYLED */ 160