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comparison lib/lua/lua-5.2.2/lgc.h @ 1866:41cc4dd3c122

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Lua 5.2.2 added.
author Nomad
date Wed, 16 Oct 2013 13:34:26 +0200
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1848:3b39b70e8e93 1866:41cc4dd3c122
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
143 LUAI_FUNC void luaC_freeallobjects (lua_State *L);
144 LUAI_FUNC void luaC_step (lua_State *L);
145 LUAI_FUNC void luaC_forcestep (lua_State *L);
146 LUAI_FUNC void luaC_runtilstate (lua_State *L, int statesmask);
147 LUAI_FUNC void luaC_fullgc (lua_State *L, int isemergency);
148 LUAI_FUNC GCObject *luaC_newobj (lua_State *L, int tt, size_t sz,
149 GCObject **list, int offset);
150 LUAI_FUNC void luaC_barrier_ (lua_State *L, GCObject *o, GCObject *v);
151 LUAI_FUNC void luaC_barrierback_ (lua_State *L, GCObject *o);
152 LUAI_FUNC void luaC_barrierproto_ (lua_State *L, Proto *p, Closure *c);
153 LUAI_FUNC void luaC_checkfinalizer (lua_State *L, GCObject *o, Table *mt);
154 LUAI_FUNC void luaC_checkupvalcolor (global_State *g, UpVal *uv);
155 LUAI_FUNC void luaC_changemode (lua_State *L, int mode);
156
157 #endif