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1087
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1 /*
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2 ** $Id: lgc.c,v 2.133 2012/05/31 21:28:59 roberto Exp $
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3 ** Garbage Collector
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4 ** See Copyright Notice in lua.h
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5 */
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6
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7 #include <string.h>
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8
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9 #define lgc_c
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10 #define LUA_CORE
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11
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12 #include "lua.h"
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13
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14 #include "ldebug.h"
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15 #include "ldo.h"
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16 #include "lfunc.h"
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17 #include "lgc.h"
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18 #include "lmem.h"
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19 #include "lobject.h"
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20 #include "lstate.h"
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21 #include "lstring.h"
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22 #include "ltable.h"
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23 #include "ltm.h"
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24
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25
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26
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27 /*
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28 ** cost of sweeping one element (the size of a small object divided
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29 ** by some adjust for the sweep speed)
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30 */
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31 #define GCSWEEPCOST ((sizeof(TString) + 4) / 4)
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32
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33 /* maximum number of elements to sweep in each single step */
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34 #define GCSWEEPMAX (cast_int((GCSTEPSIZE / GCSWEEPCOST) / 4))
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35
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36 /* maximum number of finalizers to call in each GC step */
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37 #define GCFINALIZENUM 4
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38
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39
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40 /*
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41 ** macro to adjust 'stepmul': 'stepmul' is actually used like
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42 ** 'stepmul / STEPMULADJ' (value chosen by tests)
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43 */
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44 #define STEPMULADJ 200
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45
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46 /*
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47 ** macro to adjust 'pause': 'pause' is actually used like
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48 ** 'pause / PAUSEADJ' (value chosen by tests)
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49 */
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50 #define PAUSEADJ 200
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51
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52
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53
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54
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55 /*
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56 ** standard negative debt for GC; a reasonable "time" to wait before
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57 ** starting a new cycle
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58 */
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59 #define stddebtest(g,e) (-cast(l_mem, (e)/PAUSEADJ) * g->gcpause)
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60 #define stddebt(g) stddebtest(g, gettotalbytes(g))
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61
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62
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63 /*
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64 ** 'makewhite' erases all color bits plus the old bit and then
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65 ** sets only the current white bit
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66 */
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67 #define maskcolors (~(bit2mask(BLACKBIT, OLDBIT) | WHITEBITS))
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68 #define makewhite(g,x) \
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69 (gch(x)->marked = cast_byte((gch(x)->marked & maskcolors) | luaC_white(g)))
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70
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71 #define white2gray(x) resetbits(gch(x)->marked, WHITEBITS)
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72 #define black2gray(x) resetbit(gch(x)->marked, BLACKBIT)
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73
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74
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75 #define isfinalized(x) testbit(gch(x)->marked, FINALIZEDBIT)
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76
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77 #define checkdeadkey(n) lua_assert(!ttisdeadkey(gkey(n)) || ttisnil(gval(n)))
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78
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79
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80 #define checkconsistency(obj) \
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81 lua_longassert(!iscollectable(obj) || righttt(obj))
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82
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83
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84 #define markvalue(g,o) { checkconsistency(o); \
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85 if (valiswhite(o)) reallymarkobject(g,gcvalue(o)); }
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86
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87 #define markobject(g,t) { if ((t) && iswhite(obj2gco(t))) \
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88 reallymarkobject(g, obj2gco(t)); }
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89
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90 static void reallymarkobject (global_State *g, GCObject *o);
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91
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92
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93 /*
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94 ** {======================================================
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95 ** Generic functions
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96 ** =======================================================
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97 */
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98
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99
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100 /*
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101 ** one after last element in a hash array
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102 */
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103 #define gnodelast(h) gnode(h, cast(size_t, sizenode(h)))
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104
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105
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106 /*
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107 ** link table 'h' into list pointed by 'p'
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108 */
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109 #define linktable(h,p) ((h)->gclist = *(p), *(p) = obj2gco(h))
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110
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111
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112 /*
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113 ** if key is not marked, mark its entry as dead (therefore removing it
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114 ** from the table)
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115 */
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116 static void removeentry (Node *n) {
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117 lua_assert(ttisnil(gval(n)));
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118 if (valiswhite(gkey(n)))
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119 setdeadvalue(gkey(n)); /* unused and unmarked key; remove it */
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120 }
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121
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122
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123 /*
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124 ** tells whether a key or value can be cleared from a weak
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125 ** table. Non-collectable objects are never removed from weak
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126 ** tables. Strings behave as `values', so are never removed too. for
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127 ** other objects: if really collected, cannot keep them; for objects
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128 ** being finalized, keep them in keys, but not in values
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129 */
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130 static int iscleared (global_State *g, const TValue *o) {
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131 if (!iscollectable(o)) return 0;
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132 else if (ttisstring(o)) {
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133 markobject(g, rawtsvalue(o)); /* strings are `values', so are never weak */
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134 return 0;
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135 }
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136 else return iswhite(gcvalue(o));
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137 }
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138
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139
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140 /*
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141 ** barrier that moves collector forward, that is, mark the white object
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142 ** being pointed by a black object.
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143 */
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144 void luaC_barrier_ (lua_State *L, GCObject *o, GCObject *v) {
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145 global_State *g = G(L);
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146 lua_assert(isblack(o) && iswhite(v) && !isdead(g, v) && !isdead(g, o));
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147 lua_assert(isgenerational(g) || g->gcstate != GCSpause);
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148 lua_assert(gch(o)->tt != LUA_TTABLE);
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149 if (keepinvariant(g)) /* must keep invariant? */
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150 reallymarkobject(g, v); /* restore invariant */
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151 else { /* sweep phase */
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152 lua_assert(issweepphase(g));
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153 makewhite(g, o); /* mark main obj. as white to avoid other barriers */
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154 }
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155 }
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156
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157
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158 /*
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159 ** barrier that moves collector backward, that is, mark the black object
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160 ** pointing to a white object as gray again. (Current implementation
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161 ** only works for tables; access to 'gclist' is not uniform across
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162 ** different types.)
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163 */
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164 void luaC_barrierback_ (lua_State *L, GCObject *o) {
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165 global_State *g = G(L);
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166 lua_assert(isblack(o) && !isdead(g, o) && gch(o)->tt == LUA_TTABLE);
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167 black2gray(o); /* make object gray (again) */
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168 gco2t(o)->gclist = g->grayagain;
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169 g->grayagain = o;
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170 }
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171
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172
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173 /*
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174 ** barrier for prototypes. When creating first closure (cache is
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175 ** NULL), use a forward barrier; this may be the only closure of the
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176 ** prototype (if it is a "regular" function, with a single instance)
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177 ** and the prototype may be big, so it is better to avoid traversing
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178 ** it again. Otherwise, use a backward barrier, to avoid marking all
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179 ** possible instances.
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180 */
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181 LUAI_FUNC void luaC_barrierproto_ (lua_State *L, Proto *p, Closure *c) {
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182 global_State *g = G(L);
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183 lua_assert(isblack(obj2gco(p)));
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184 if (p->cache == NULL) { /* first time? */
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185 luaC_objbarrier(L, p, c);
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186 }
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187 else { /* use a backward barrier */
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188 black2gray(obj2gco(p)); /* make prototype gray (again) */
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189 p->gclist = g->grayagain;
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190 g->grayagain = obj2gco(p);
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191 }
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192 }
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193
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194
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195 /*
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196 ** check color (and invariants) for an upvalue that was closed,
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197 ** i.e., moved into the 'allgc' list
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198 */
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199 void luaC_checkupvalcolor (global_State *g, UpVal *uv) {
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200 GCObject *o = obj2gco(uv);
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201 lua_assert(!isblack(o)); /* open upvalues are never black */
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202 if (isgray(o)) {
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203 if (keepinvariant(g)) {
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204 resetoldbit(o); /* see MOVE OLD rule */
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205 gray2black(o); /* it is being visited now */
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206 markvalue(g, uv->v);
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207 }
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208 else {
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209 lua_assert(issweepphase(g));
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210 makewhite(g, o);
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211 }
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212 }
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213 }
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214
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215
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216 /*
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217 ** create a new collectable object (with given type and size) and link
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218 ** it to '*list'. 'offset' tells how many bytes to allocate before the
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219 ** object itself (used only by states).
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220 */
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221 GCObject *luaC_newobj (lua_State *L, int tt, size_t sz, GCObject **list,
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222 int offset) {
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223 global_State *g = G(L);
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224 char *raw = cast(char *, luaM_newobject(L, novariant(tt), sz));
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225 GCObject *o = obj2gco(raw + offset);
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226 if (list == NULL)
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227 list = &g->allgc; /* standard list for collectable objects */
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228 gch(o)->marked = luaC_white(g);
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229 gch(o)->tt = tt;
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230 gch(o)->next = *list;
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231 *list = o;
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232 return o;
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233 }
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234
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235 /* }====================================================== */
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236
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237
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238
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239 /*
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240 ** {======================================================
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241 ** Mark functions
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242 ** =======================================================
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243 */
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244
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245
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246 /*
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247 ** mark an object. Userdata, strings, and closed upvalues are visited
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248 ** and turned black here. Other objects are marked gray and added
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249 ** to appropriate list to be visited (and turned black) later. (Open
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250 ** upvalues are already linked in 'headuv' list.)
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251 */
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252 static void reallymarkobject (global_State *g, GCObject *o) {
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253 lu_mem size;
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254 white2gray(o);
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255 switch (gch(o)->tt) {
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256 case LUA_TSHRSTR:
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257 case LUA_TLNGSTR: {
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258 size = sizestring(gco2ts(o));
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259 break; /* nothing else to mark; make it black */
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260 }
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261 case LUA_TUSERDATA: {
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262 Table *mt = gco2u(o)->metatable;
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263 markobject(g, mt);
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264 markobject(g, gco2u(o)->env);
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265 size = sizeudata(gco2u(o));
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266 break;
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267 }
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268 case LUA_TUPVAL: {
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269 UpVal *uv = gco2uv(o);
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270 markvalue(g, uv->v);
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271 if (uv->v != &uv->u.value) /* open? */
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272 return; /* open upvalues remain gray */
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273 size = sizeof(UpVal);
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274 break;
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275 }
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276 case LUA_TLCL: {
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277 gco2lcl(o)->gclist = g->gray;
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278 g->gray = o;
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279 return;
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280 }
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281 case LUA_TCCL: {
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282 gco2ccl(o)->gclist = g->gray;
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283 g->gray = o;
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284 return;
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285 }
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286 case LUA_TTABLE: {
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287 linktable(gco2t(o), &g->gray);
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288 return;
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289 }
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290 case LUA_TTHREAD: {
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291 gco2th(o)->gclist = g->gray;
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292 g->gray = o;
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293 return;
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294 }
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295 case LUA_TPROTO: {
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296 gco2p(o)->gclist = g->gray;
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297 g->gray = o;
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298 return;
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299 }
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300 default: lua_assert(0); return;
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301 }
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302 gray2black(o);
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303 g->GCmemtrav += size;
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304 }
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305
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306
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307 /*
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308 ** mark metamethods for basic types
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309 */
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310 static void markmt (global_State *g) {
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311 int i;
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312 for (i=0; i < LUA_NUMTAGS; i++)
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313 markobject(g, g->mt[i]);
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314 }
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315
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316
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317 /*
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318 ** mark all objects in list of being-finalized
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319 */
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320 static void markbeingfnz (global_State *g) {
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321 GCObject *o;
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322 for (o = g->tobefnz; o != NULL; o = gch(o)->next) {
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323 makewhite(g, o);
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324 reallymarkobject(g, o);
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325 }
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326 }
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327
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328
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329 /*
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330 ** mark all values stored in marked open upvalues. (See comment in
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331 ** 'lstate.h'.)
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332 */
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333 static void remarkupvals (global_State *g) {
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334 UpVal *uv;
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335 for (uv = g->uvhead.u.l.next; uv != &g->uvhead; uv = uv->u.l.next) {
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336 if (isgray(obj2gco(uv)))
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337 markvalue(g, uv->v);
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338 }
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339 }
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340
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341
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342 /*
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343 ** mark root set and reset all gray lists, to start a new
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344 ** incremental (or full) collection
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345 */
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346 static void markroot (global_State *g) {
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347 g->gray = g->grayagain = NULL;
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348 g->weak = g->allweak = g->ephemeron = NULL;
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349 markobject(g, g->mainthread);
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350 markvalue(g, &g->l_registry);
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351 markmt(g);
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352 markbeingfnz(g); /* mark any finalizing object left from previous cycle */
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353 }
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354
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355 /* }====================================================== */
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356
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357
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358 /*
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359 ** {======================================================
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360 ** Traverse functions
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361 ** =======================================================
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362 */
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363
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364 static void traverseweakvalue (global_State *g, Table *h) {
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365 Node *n, *limit = gnodelast(h);
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366 /* if there is array part, assume it may have white values (do not
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367 traverse it just to check) */
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368 int hasclears = (h->sizearray > 0);
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369 for (n = gnode(h, 0); n < limit; n++) {
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370 checkdeadkey(n);
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371 if (ttisnil(gval(n))) /* entry is empty? */
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372 removeentry(n); /* remove it */
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373 else {
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374 lua_assert(!ttisnil(gkey(n)));
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375 markvalue(g, gkey(n)); /* mark key */
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376 if (!hasclears && iscleared(g, gval(n))) /* is there a white value? */
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377 hasclears = 1; /* table will have to be cleared */
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378 }
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379 }
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380 if (hasclears)
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381 linktable(h, &g->weak); /* has to be cleared later */
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382 else /* no white values */
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383 linktable(h, &g->grayagain); /* no need to clean */
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384 }
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385
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386
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387 static int traverseephemeron (global_State *g, Table *h) {
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388 int marked = 0; /* true if an object is marked in this traversal */
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389 int hasclears = 0; /* true if table has white keys */
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390 int prop = 0; /* true if table has entry "white-key -> white-value" */
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391 Node *n, *limit = gnodelast(h);
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392 int i;
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393 /* traverse array part (numeric keys are 'strong') */
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394 for (i = 0; i < h->sizearray; i++) {
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395 if (valiswhite(&h->array[i])) {
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396 marked = 1;
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397 reallymarkobject(g, gcvalue(&h->array[i]));
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398 }
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399 }
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400 /* traverse hash part */
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401 for (n = gnode(h, 0); n < limit; n++) {
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402 checkdeadkey(n);
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403 if (ttisnil(gval(n))) /* entry is empty? */
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404 removeentry(n); /* remove it */
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405 else if (iscleared(g, gkey(n))) { /* key is not marked (yet)? */
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406 hasclears = 1; /* table must be cleared */
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407 if (valiswhite(gval(n))) /* value not marked yet? */
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408 prop = 1; /* must propagate again */
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409 }
|
|
|
410 else if (valiswhite(gval(n))) { /* value not marked yet? */
|
|
|
411 marked = 1;
|
|
|
412 reallymarkobject(g, gcvalue(gval(n))); /* mark it now */
|
|
|
413 }
|
|
|
414 }
|
|
|
415 if (prop)
|
|
|
416 linktable(h, &g->ephemeron); /* have to propagate again */
|
|
|
417 else if (hasclears) /* does table have white keys? */
|
|
|
418 linktable(h, &g->allweak); /* may have to clean white keys */
|
|
|
419 else /* no white keys */
|
|
|
420 linktable(h, &g->grayagain); /* no need to clean */
|
|
|
421 return marked;
|
|
|
422 }
|
|
|
423
|
|
|
424
|
|
|
425 static void traversestrongtable (global_State *g, Table *h) {
|
|
|
426 Node *n, *limit = gnodelast(h);
|
|
|
427 int i;
|
|
|
428 for (i = 0; i < h->sizearray; i++) /* traverse array part */
|
|
|
429 markvalue(g, &h->array[i]);
|
|
|
430 for (n = gnode(h, 0); n < limit; n++) { /* traverse hash part */
|
|
|
431 checkdeadkey(n);
|
|
|
432 if (ttisnil(gval(n))) /* entry is empty? */
|
|
|
433 removeentry(n); /* remove it */
|
|
|
434 else {
|
|
|
435 lua_assert(!ttisnil(gkey(n)));
|
|
|
436 markvalue(g, gkey(n)); /* mark key */
|
|
|
437 markvalue(g, gval(n)); /* mark value */
|
|
|
438 }
|
|
|
439 }
|
|
|
440 }
|
|
|
441
|
|
|
442
|
|
|
443 static lu_mem traversetable (global_State *g, Table *h) {
|
|
|
444 const char *weakkey, *weakvalue;
|
|
|
445 const TValue *mode = gfasttm(g, h->metatable, TM_MODE);
|
|
|
446 markobject(g, h->metatable);
|
|
|
447 if (mode && ttisstring(mode) && /* is there a weak mode? */
|
|
|
448 ((weakkey = strchr(svalue(mode), 'k')),
|
|
|
449 (weakvalue = strchr(svalue(mode), 'v')),
|
|
|
450 (weakkey || weakvalue))) { /* is really weak? */
|
|
|
451 black2gray(obj2gco(h)); /* keep table gray */
|
|
|
452 if (!weakkey) /* strong keys? */
|
|
|
453 traverseweakvalue(g, h);
|
|
|
454 else if (!weakvalue) /* strong values? */
|
|
|
455 traverseephemeron(g, h);
|
|
|
456 else /* all weak */
|
|
|
457 linktable(h, &g->allweak); /* nothing to traverse now */
|
|
|
458 }
|
|
|
459 else /* not weak */
|
|
|
460 traversestrongtable(g, h);
|
|
|
461 return sizeof(Table) + sizeof(TValue) * h->sizearray +
|
|
|
462 sizeof(Node) * sizenode(h);
|
|
|
463 }
|
|
|
464
|
|
|
465
|
|
|
466 static int traverseproto (global_State *g, Proto *f) {
|
|
|
467 int i;
|
|
|
468 if (f->cache && iswhite(obj2gco(f->cache)))
|
|
|
469 f->cache = NULL; /* allow cache to be collected */
|
|
|
470 markobject(g, f->source);
|
|
|
471 for (i = 0; i < f->sizek; i++) /* mark literals */
|
|
|
472 markvalue(g, &f->k[i]);
|
|
|
473 for (i = 0; i < f->sizeupvalues; i++) /* mark upvalue names */
|
|
|
474 markobject(g, f->upvalues[i].name);
|
|
|
475 for (i = 0; i < f->sizep; i++) /* mark nested protos */
|
|
|
476 markobject(g, f->p[i]);
|
|
|
477 for (i = 0; i < f->sizelocvars; i++) /* mark local-variable names */
|
|
|
478 markobject(g, f->locvars[i].varname);
|
|
|
479 return sizeof(Proto) + sizeof(Instruction) * f->sizecode +
|
|
|
480 sizeof(Proto *) * f->sizep +
|
|
|
481 sizeof(TValue) * f->sizek +
|
|
|
482 sizeof(int) * f->sizelineinfo +
|
|
|
483 sizeof(LocVar) * f->sizelocvars +
|
|
|
484 sizeof(Upvaldesc) * f->sizeupvalues;
|
|
|
485 }
|
|
|
486
|
|
|
487
|
|
|
488 static lu_mem traverseCclosure (global_State *g, CClosure *cl) {
|
|
|
489 int i;
|
|
|
490 for (i = 0; i < cl->nupvalues; i++) /* mark its upvalues */
|
|
|
491 markvalue(g, &cl->upvalue[i]);
|
|
|
492 return sizeCclosure(cl->nupvalues);
|
|
|
493 }
|
|
|
494
|
|
|
495 static lu_mem traverseLclosure (global_State *g, LClosure *cl) {
|
|
|
496 int i;
|
|
|
497 markobject(g, cl->p); /* mark its prototype */
|
|
|
498 for (i = 0; i < cl->nupvalues; i++) /* mark its upvalues */
|
|
|
499 markobject(g, cl->upvals[i]);
|
|
|
500 return sizeLclosure(cl->nupvalues);
|
|
|
501 }
|
|
|
502
|
|
|
503
|
|
|
504 static lu_mem traversestack (global_State *g, lua_State *th) {
|
|
|
505 StkId o = th->stack;
|
|
|
506 if (o == NULL)
|
|
|
507 return 1; /* stack not completely built yet */
|
|
|
508 for (; o < th->top; o++)
|
|
|
509 markvalue(g, o);
|
|
|
510 if (g->gcstate == GCSatomic) { /* final traversal? */
|
|
|
511 StkId lim = th->stack + th->stacksize; /* real end of stack */
|
|
|
512 for (; o < lim; o++) /* clear not-marked stack slice */
|
|
|
513 setnilvalue(o);
|
|
|
514 }
|
|
|
515 return sizeof(lua_State) + sizeof(TValue) * th->stacksize;
|
|
|
516 }
|
|
|
517
|
|
|
518
|
|
|
519 /*
|
|
|
520 ** traverse one gray object, turning it to black (except for threads,
|
|
|
521 ** which are always gray).
|
|
|
522 */
|
|
|
523 static void propagatemark (global_State *g) {
|
|
|
524 lu_mem size;
|
|
|
525 GCObject *o = g->gray;
|
|
|
526 lua_assert(isgray(o));
|
|
|
527 gray2black(o);
|
|
|
528 switch (gch(o)->tt) {
|
|
|
529 case LUA_TTABLE: {
|
|
|
530 Table *h = gco2t(o);
|
|
|
531 g->gray = h->gclist; /* remove from 'gray' list */
|
|
|
532 size = traversetable(g, h);
|
|
|
533 break;
|
|
|
534 }
|
|
|
535 case LUA_TLCL: {
|
|
|
536 LClosure *cl = gco2lcl(o);
|
|
|
537 g->gray = cl->gclist; /* remove from 'gray' list */
|
|
|
538 size = traverseLclosure(g, cl);
|
|
|
539 break;
|
|
|
540 }
|
|
|
541 case LUA_TCCL: {
|
|
|
542 CClosure *cl = gco2ccl(o);
|
|
|
543 g->gray = cl->gclist; /* remove from 'gray' list */
|
|
|
544 size = traverseCclosure(g, cl);
|
|
|
545 break;
|
|
|
546 }
|
|
|
547 case LUA_TTHREAD: {
|
|
|
548 lua_State *th = gco2th(o);
|
|
|
549 g->gray = th->gclist; /* remove from 'gray' list */
|
|
|
550 th->gclist = g->grayagain;
|
|
|
551 g->grayagain = o; /* insert into 'grayagain' list */
|
|
|
552 black2gray(o);
|
|
|
553 size = traversestack(g, th);
|
|
|
554 break;
|
|
|
555 }
|
|
|
556 case LUA_TPROTO: {
|
|
|
557 Proto *p = gco2p(o);
|
|
|
558 g->gray = p->gclist; /* remove from 'gray' list */
|
|
|
559 size = traverseproto(g, p);
|
|
|
560 break;
|
|
|
561 }
|
|
|
562 default: lua_assert(0); return;
|
|
|
563 }
|
|
|
564 g->GCmemtrav += size;
|
|
|
565 }
|
|
|
566
|
|
|
567
|
|
|
568 static void propagateall (global_State *g) {
|
|
|
569 while (g->gray) propagatemark(g);
|
|
|
570 }
|
|
|
571
|
|
|
572
|
|
|
573 static void propagatelist (global_State *g, GCObject *l) {
|
|
|
574 lua_assert(g->gray == NULL); /* no grays left */
|
|
|
575 g->gray = l;
|
|
|
576 propagateall(g); /* traverse all elements from 'l' */
|
|
|
577 }
|
|
|
578
|
|
|
579 /*
|
|
|
580 ** retraverse all gray lists. Because tables may be reinserted in other
|
|
|
581 ** lists when traversed, traverse the original lists to avoid traversing
|
|
|
582 ** twice the same table (which is not wrong, but inefficient)
|
|
|
583 */
|
|
|
584 static void retraversegrays (global_State *g) {
|
|
|
585 GCObject *weak = g->weak; /* save original lists */
|
|
|
586 GCObject *grayagain = g->grayagain;
|
|
|
587 GCObject *ephemeron = g->ephemeron;
|
|
|
588 g->weak = g->grayagain = g->ephemeron = NULL;
|
|
|
589 propagateall(g); /* traverse main gray list */
|
|
|
590 propagatelist(g, grayagain);
|
|
|
591 propagatelist(g, weak);
|
|
|
592 propagatelist(g, ephemeron);
|
|
|
593 }
|
|
|
594
|
|
|
595
|
|
|
596 static void convergeephemerons (global_State *g) {
|
|
|
597 int changed;
|
|
|
598 do {
|
|
|
599 GCObject *w;
|
|
|
600 GCObject *next = g->ephemeron; /* get ephemeron list */
|
|
|
601 g->ephemeron = NULL; /* tables will return to this list when traversed */
|
|
|
602 changed = 0;
|
|
|
603 while ((w = next) != NULL) {
|
|
|
604 next = gco2t(w)->gclist;
|
|
|
605 if (traverseephemeron(g, gco2t(w))) { /* traverse marked some value? */
|
|
|
606 propagateall(g); /* propagate changes */
|
|
|
607 changed = 1; /* will have to revisit all ephemeron tables */
|
|
|
608 }
|
|
|
609 }
|
|
|
610 } while (changed);
|
|
|
611 }
|
|
|
612
|
|
|
613 /* }====================================================== */
|
|
|
614
|
|
|
615
|
|
|
616 /*
|
|
|
617 ** {======================================================
|
|
|
618 ** Sweep Functions
|
|
|
619 ** =======================================================
|
|
|
620 */
|
|
|
621
|
|
|
622
|
|
|
623 /*
|
|
|
624 ** clear entries with unmarked keys from all weaktables in list 'l' up
|
|
|
625 ** to element 'f'
|
|
|
626 */
|
|
|
627 static void clearkeys (global_State *g, GCObject *l, GCObject *f) {
|
|
|
628 for (; l != f; l = gco2t(l)->gclist) {
|
|
|
629 Table *h = gco2t(l);
|
|
|
630 Node *n, *limit = gnodelast(h);
|
|
|
631 for (n = gnode(h, 0); n < limit; n++) {
|
|
|
632 if (!ttisnil(gval(n)) && (iscleared(g, gkey(n)))) {
|
|
|
633 setnilvalue(gval(n)); /* remove value ... */
|
|
|
634 removeentry(n); /* and remove entry from table */
|
|
|
635 }
|
|
|
636 }
|
|
|
637 }
|
|
|
638 }
|
|
|
639
|
|
|
640
|
|
|
641 /*
|
|
|
642 ** clear entries with unmarked values from all weaktables in list 'l' up
|
|
|
643 ** to element 'f'
|
|
|
644 */
|
|
|
645 static void clearvalues (global_State *g, GCObject *l, GCObject *f) {
|
|
|
646 for (; l != f; l = gco2t(l)->gclist) {
|
|
|
647 Table *h = gco2t(l);
|
|
|
648 Node *n, *limit = gnodelast(h);
|
|
|
649 int i;
|
|
|
650 for (i = 0; i < h->sizearray; i++) {
|
|
|
651 TValue *o = &h->array[i];
|
|
|
652 if (iscleared(g, o)) /* value was collected? */
|
|
|
653 setnilvalue(o); /* remove value */
|
|
|
654 }
|
|
|
655 for (n = gnode(h, 0); n < limit; n++) {
|
|
|
656 if (!ttisnil(gval(n)) && iscleared(g, gval(n))) {
|
|
|
657 setnilvalue(gval(n)); /* remove value ... */
|
|
|
658 removeentry(n); /* and remove entry from table */
|
|
|
659 }
|
|
|
660 }
|
|
|
661 }
|
|
|
662 }
|
|
|
663
|
|
|
664
|
|
|
665 static void freeobj (lua_State *L, GCObject *o) {
|
|
|
666 switch (gch(o)->tt) {
|
|
|
667 case LUA_TPROTO: luaF_freeproto(L, gco2p(o)); break;
|
|
|
668 case LUA_TLCL: {
|
|
|
669 luaM_freemem(L, o, sizeLclosure(gco2lcl(o)->nupvalues));
|
|
|
670 break;
|
|
|
671 }
|
|
|
672 case LUA_TCCL: {
|
|
|
673 luaM_freemem(L, o, sizeCclosure(gco2ccl(o)->nupvalues));
|
|
|
674 break;
|
|
|
675 }
|
|
|
676 case LUA_TUPVAL: luaF_freeupval(L, gco2uv(o)); break;
|
|
|
677 case LUA_TTABLE: luaH_free(L, gco2t(o)); break;
|
|
|
678 case LUA_TTHREAD: luaE_freethread(L, gco2th(o)); break;
|
|
|
679 case LUA_TUSERDATA: luaM_freemem(L, o, sizeudata(gco2u(o))); break;
|
|
|
680 case LUA_TSHRSTR:
|
|
|
681 G(L)->strt.nuse--;
|
|
|
682 /* go through */
|
|
|
683 case LUA_TLNGSTR: {
|
|
|
684 luaM_freemem(L, o, sizestring(gco2ts(o)));
|
|
|
685 break;
|
|
|
686 }
|
|
|
687 default: lua_assert(0);
|
|
|
688 }
|
|
|
689 }
|
|
|
690
|
|
|
691
|
|
|
692 #define sweepwholelist(L,p) sweeplist(L,p,MAX_LUMEM)
|
|
|
693 static GCObject **sweeplist (lua_State *L, GCObject **p, lu_mem count);
|
|
|
694
|
|
|
695
|
|
|
696 /*
|
|
|
697 ** sweep the (open) upvalues of a thread and resize its stack and
|
|
|
698 ** list of call-info structures.
|
|
|
699 */
|
|
|
700 static void sweepthread (lua_State *L, lua_State *L1) {
|
|
|
701 if (L1->stack == NULL) return; /* stack not completely built yet */
|
|
|
702 sweepwholelist(L, &L1->openupval); /* sweep open upvalues */
|
|
|
703 luaE_freeCI(L1); /* free extra CallInfo slots */
|
|
|
704 /* should not change the stack during an emergency gc cycle */
|
|
|
705 if (G(L)->gckind != KGC_EMERGENCY)
|
|
|
706 luaD_shrinkstack(L1);
|
|
|
707 }
|
|
|
708
|
|
|
709
|
|
|
710 /*
|
|
|
711 ** sweep at most 'count' elements from a list of GCObjects erasing dead
|
|
|
712 ** objects, where a dead (not alive) object is one marked with the "old"
|
|
|
713 ** (non current) white and not fixed.
|
|
|
714 ** In non-generational mode, change all non-dead objects back to white,
|
|
|
715 ** preparing for next collection cycle.
|
|
|
716 ** In generational mode, keep black objects black, and also mark them as
|
|
|
717 ** old; stop when hitting an old object, as all objects after that
|
|
|
718 ** one will be old too.
|
|
|
719 ** When object is a thread, sweep its list of open upvalues too.
|
|
|
720 */
|
|
|
721 static GCObject **sweeplist (lua_State *L, GCObject **p, lu_mem count) {
|
|
|
722 global_State *g = G(L);
|
|
|
723 int ow = otherwhite(g);
|
|
|
724 int toclear, toset; /* bits to clear and to set in all live objects */
|
|
|
725 int tostop; /* stop sweep when this is true */
|
|
|
726 if (isgenerational(g)) { /* generational mode? */
|
|
|
727 toclear = ~0; /* clear nothing */
|
|
|
728 toset = bitmask(OLDBIT); /* set the old bit of all surviving objects */
|
|
|
729 tostop = bitmask(OLDBIT); /* do not sweep old generation */
|
|
|
730 }
|
|
|
731 else { /* normal mode */
|
|
|
732 toclear = maskcolors; /* clear all color bits + old bit */
|
|
|
733 toset = luaC_white(g); /* make object white */
|
|
|
734 tostop = 0; /* do not stop */
|
|
|
735 }
|
|
|
736 while (*p != NULL && count-- > 0) {
|
|
|
737 GCObject *curr = *p;
|
|
|
738 int marked = gch(curr)->marked;
|
|
|
739 if (isdeadm(ow, marked)) { /* is 'curr' dead? */
|
|
|
740 *p = gch(curr)->next; /* remove 'curr' from list */
|
|
|
741 freeobj(L, curr); /* erase 'curr' */
|
|
|
742 }
|
|
|
743 else {
|
|
|
744 if (testbits(marked, tostop))
|
|
|
745 return NULL; /* stop sweeping this list */
|
|
|
746 if (gch(curr)->tt == LUA_TTHREAD)
|
|
|
747 sweepthread(L, gco2th(curr)); /* sweep thread's upvalues */
|
|
|
748 /* update marks */
|
|
|
749 gch(curr)->marked = cast_byte((marked & toclear) | toset);
|
|
|
750 p = &gch(curr)->next; /* go to next element */
|
|
|
751 }
|
|
|
752 }
|
|
|
753 return (*p == NULL) ? NULL : p;
|
|
|
754 }
|
|
|
755
|
|
|
756
|
|
|
757 /*
|
|
|
758 ** sweep a list until a live object (or end of list)
|
|
|
759 */
|
|
|
760 static GCObject **sweeptolive (lua_State *L, GCObject **p, int *n) {
|
|
|
761 GCObject ** old = p;
|
|
|
762 int i = 0;
|
|
|
763 do {
|
|
|
764 i++;
|
|
|
765 p = sweeplist(L, p, 1);
|
|
|
766 } while (p == old);
|
|
|
767 if (n) *n += i;
|
|
|
768 return p;
|
|
|
769 }
|
|
|
770
|
|
|
771 /* }====================================================== */
|
|
|
772
|
|
|
773
|
|
|
774 /*
|
|
|
775 ** {======================================================
|
|
|
776 ** Finalization
|
|
|
777 ** =======================================================
|
|
|
778 */
|
|
|
779
|
|
|
780 static void checkSizes (lua_State *L) {
|
|
|
781 global_State *g = G(L);
|
|
|
782 if (g->gckind != KGC_EMERGENCY) { /* do not change sizes in emergency */
|
|
|
783 int hs = g->strt.size / 2; /* half the size of the string table */
|
|
|
784 if (g->strt.nuse < cast(lu_int32, hs)) /* using less than that half? */
|
|
|
785 luaS_resize(L, hs); /* halve its size */
|
|
|
786 luaZ_freebuffer(L, &g->buff); /* free concatenation buffer */
|
|
|
787 }
|
|
|
788 }
|
|
|
789
|
|
|
790
|
|
|
791 static GCObject *udata2finalize (global_State *g) {
|
|
|
792 GCObject *o = g->tobefnz; /* get first element */
|
|
|
793 lua_assert(isfinalized(o));
|
|
|
794 g->tobefnz = gch(o)->next; /* remove it from 'tobefnz' list */
|
|
|
795 gch(o)->next = g->allgc; /* return it to 'allgc' list */
|
|
|
796 g->allgc = o;
|
|
|
797 resetbit(gch(o)->marked, SEPARATED); /* mark that it is not in 'tobefnz' */
|
|
|
798 lua_assert(!isold(o)); /* see MOVE OLD rule */
|
|
|
799 if (!keepinvariant(g)) /* not keeping invariant? */
|
|
|
800 makewhite(g, o); /* "sweep" object */
|
|
|
801 return o;
|
|
|
802 }
|
|
|
803
|
|
|
804
|
|
|
805 static void dothecall (lua_State *L, void *ud) {
|
|
|
806 UNUSED(ud);
|
|
|
807 luaD_call(L, L->top - 2, 0, 0);
|
|
|
808 }
|
|
|
809
|
|
|
810
|
|
|
811 static void GCTM (lua_State *L, int propagateerrors) {
|
|
|
812 global_State *g = G(L);
|
|
|
813 const TValue *tm;
|
|
|
814 TValue v;
|
|
|
815 setgcovalue(L, &v, udata2finalize(g));
|
|
|
816 tm = luaT_gettmbyobj(L, &v, TM_GC);
|
|
|
817 if (tm != NULL && ttisfunction(tm)) { /* is there a finalizer? */
|
|
|
818 int status;
|
|
|
819 lu_byte oldah = L->allowhook;
|
|
|
820 int running = g->gcrunning;
|
|
|
821 L->allowhook = 0; /* stop debug hooks during GC metamethod */
|
|
|
822 g->gcrunning = 0; /* avoid GC steps */
|
|
|
823 setobj2s(L, L->top, tm); /* push finalizer... */
|
|
|
824 setobj2s(L, L->top + 1, &v); /* ... and its argument */
|
|
|
825 L->top += 2; /* and (next line) call the finalizer */
|
|
|
826 status = luaD_pcall(L, dothecall, NULL, savestack(L, L->top - 2), 0);
|
|
|
827 L->allowhook = oldah; /* restore hooks */
|
|
|
828 g->gcrunning = running; /* restore state */
|
|
|
829 if (status != LUA_OK && propagateerrors) { /* error while running __gc? */
|
|
|
830 if (status == LUA_ERRRUN) { /* is there an error object? */
|
|
|
831 const char *msg = (ttisstring(L->top - 1))
|
|
|
832 ? svalue(L->top - 1)
|
|
|
833 : "no message";
|
|
|
834 luaO_pushfstring(L, "error in __gc metamethod (%s)", msg);
|
|
|
835 status = LUA_ERRGCMM; /* error in __gc metamethod */
|
|
|
836 }
|
|
|
837 luaD_throw(L, status); /* re-throw error */
|
|
|
838 }
|
|
|
839 }
|
|
|
840 }
|
|
|
841
|
|
|
842
|
|
|
843 /*
|
|
|
844 ** move all unreachable objects (or 'all' objects) that need
|
|
|
845 ** finalization from list 'finobj' to list 'tobefnz' (to be finalized)
|
|
|
846 */
|
|
|
847 static void separatetobefnz (lua_State *L, int all) {
|
|
|
848 global_State *g = G(L);
|
|
|
849 GCObject **p = &g->finobj;
|
|
|
850 GCObject *curr;
|
|
|
851 GCObject **lastnext = &g->tobefnz;
|
|
|
852 /* find last 'next' field in 'tobefnz' list (to add elements in its end) */
|
|
|
853 while (*lastnext != NULL)
|
|
|
854 lastnext = &gch(*lastnext)->next;
|
|
|
855 while ((curr = *p) != NULL) { /* traverse all finalizable objects */
|
|
|
856 lua_assert(!isfinalized(curr));
|
|
|
857 lua_assert(testbit(gch(curr)->marked, SEPARATED));
|
|
|
858 if (!(all || iswhite(curr))) /* not being collected? */
|
|
|
859 p = &gch(curr)->next; /* don't bother with it */
|
|
|
860 else {
|
|
|
861 l_setbit(gch(curr)->marked, FINALIZEDBIT); /* won't be finalized again */
|
|
|
862 *p = gch(curr)->next; /* remove 'curr' from 'finobj' list */
|
|
|
863 gch(curr)->next = *lastnext; /* link at the end of 'tobefnz' list */
|
|
|
864 *lastnext = curr;
|
|
|
865 lastnext = &gch(curr)->next;
|
|
|
866 }
|
|
|
867 }
|
|
|
868 }
|
|
|
869
|
|
|
870
|
|
|
871 /*
|
|
|
872 ** if object 'o' has a finalizer, remove it from 'allgc' list (must
|
|
|
873 ** search the list to find it) and link it in 'finobj' list.
|
|
|
874 */
|
|
|
875 void luaC_checkfinalizer (lua_State *L, GCObject *o, Table *mt) {
|
|
|
876 global_State *g = G(L);
|
|
|
877 if (testbit(gch(o)->marked, SEPARATED) || /* obj. is already separated... */
|
|
|
878 isfinalized(o) || /* ... or is finalized... */
|
|
|
879 gfasttm(g, mt, TM_GC) == NULL) /* or has no finalizer? */
|
|
|
880 return; /* nothing to be done */
|
|
|
881 else { /* move 'o' to 'finobj' list */
|
|
|
882 GCObject **p;
|
|
|
883 GCheader *ho = gch(o);
|
|
|
884 if (g->sweepgc == &ho->next) { /* avoid removing current sweep object */
|
|
|
885 lua_assert(issweepphase(g));
|
|
|
886 g->sweepgc = sweeptolive(L, g->sweepgc, NULL);
|
|
|
887 }
|
|
|
888 /* search for pointer pointing to 'o' */
|
|
|
889 for (p = &g->allgc; *p != o; p = &gch(*p)->next) { /* empty */ }
|
|
|
890 *p = ho->next; /* remove 'o' from root list */
|
|
|
891 ho->next = g->finobj; /* link it in list 'finobj' */
|
|
|
892 g->finobj = o;
|
|
|
893 l_setbit(ho->marked, SEPARATED); /* mark it as such */
|
|
|
894 if (!keepinvariant(g)) /* not keeping invariant? */
|
|
|
895 makewhite(g, o); /* "sweep" object */
|
|
|
896 else
|
|
|
897 resetoldbit(o); /* see MOVE OLD rule */
|
|
|
898 }
|
|
|
899 }
|
|
|
900
|
|
|
901 /* }====================================================== */
|
|
|
902
|
|
|
903
|
|
|
904 /*
|
|
|
905 ** {======================================================
|
|
|
906 ** GC control
|
|
|
907 ** =======================================================
|
|
|
908 */
|
|
|
909
|
|
|
910
|
|
|
911 #define sweepphases \
|
|
|
912 (bitmask(GCSsweepstring) | bitmask(GCSsweepudata) | bitmask(GCSsweep))
|
|
|
913
|
|
|
914
|
|
|
915 /*
|
|
|
916 ** enter first sweep phase (strings) and prepare pointers for other
|
|
|
917 ** sweep phases. The calls to 'sweeptolive' make pointers point to an
|
|
|
918 ** object inside the list (instead of to the header), so that the real
|
|
|
919 ** sweep do not need to skip objects created between "now" and the start
|
|
|
920 ** of the real sweep.
|
|
|
921 ** Returns how many objects it sweeped.
|
|
|
922 */
|
|
|
923 static int entersweep (lua_State *L) {
|
|
|
924 global_State *g = G(L);
|
|
|
925 int n = 0;
|
|
|
926 g->gcstate = GCSsweepstring;
|
|
|
927 lua_assert(g->sweepgc == NULL && g->sweepfin == NULL);
|
|
|
928 /* prepare to sweep strings, finalizable objects, and regular objects */
|
|
|
929 g->sweepstrgc = 0;
|
|
|
930 g->sweepfin = sweeptolive(L, &g->finobj, &n);
|
|
|
931 g->sweepgc = sweeptolive(L, &g->allgc, &n);
|
|
|
932 return n;
|
|
|
933 }
|
|
|
934
|
|
|
935
|
|
|
936 /*
|
|
|
937 ** change GC mode
|
|
|
938 */
|
|
|
939 void luaC_changemode (lua_State *L, int mode) {
|
|
|
940 global_State *g = G(L);
|
|
|
941 if (mode == g->gckind) return; /* nothing to change */
|
|
|
942 if (mode == KGC_GEN) { /* change to generational mode */
|
|
|
943 /* make sure gray lists are consistent */
|
|
|
944 luaC_runtilstate(L, bitmask(GCSpropagate));
|
|
|
945 g->GCestimate = gettotalbytes(g);
|
|
|
946 g->gckind = KGC_GEN;
|
|
|
947 }
|
|
|
948 else { /* change to incremental mode */
|
|
|
949 /* sweep all objects to turn them back to white
|
|
|
950 (as white has not changed, nothing extra will be collected) */
|
|
|
951 g->gckind = KGC_NORMAL;
|
|
|
952 entersweep(L);
|
|
|
953 luaC_runtilstate(L, ~sweepphases);
|
|
|
954 }
|
|
|
955 }
|
|
|
956
|
|
|
957
|
|
|
958 /*
|
|
|
959 ** call all pending finalizers
|
|
|
960 */
|
|
|
961 static void callallpendingfinalizers (lua_State *L, int propagateerrors) {
|
|
|
962 global_State *g = G(L);
|
|
|
963 while (g->tobefnz) {
|
|
|
964 resetoldbit(g->tobefnz);
|
|
|
965 GCTM(L, propagateerrors);
|
|
|
966 }
|
|
|
967 }
|
|
|
968
|
|
|
969
|
|
|
970 void luaC_freeallobjects (lua_State *L) {
|
|
|
971 global_State *g = G(L);
|
|
|
972 int i;
|
|
|
973 separatetobefnz(L, 1); /* separate all objects with finalizers */
|
|
|
974 lua_assert(g->finobj == NULL);
|
|
|
975 callallpendingfinalizers(L, 0);
|
|
|
976 g->currentwhite = WHITEBITS; /* this "white" makes all objects look dead */
|
|
|
977 g->gckind = KGC_NORMAL;
|
|
|
978 sweepwholelist(L, &g->finobj); /* finalizers can create objs. in 'finobj' */
|
|
|
979 sweepwholelist(L, &g->allgc);
|
|
|
980 for (i = 0; i < g->strt.size; i++) /* free all string lists */
|
|
|
981 sweepwholelist(L, &g->strt.hash[i]);
|
|
|
982 lua_assert(g->strt.nuse == 0);
|
|
|
983 }
|
|
|
984
|
|
|
985
|
|
|
986 static l_mem atomic (lua_State *L) {
|
|
|
987 global_State *g = G(L);
|
|
|
988 l_mem work = -g->GCmemtrav; /* start counting work */
|
|
|
989 GCObject *origweak, *origall;
|
|
|
990 lua_assert(!iswhite(obj2gco(g->mainthread)));
|
|
|
991 markobject(g, L); /* mark running thread */
|
|
|
992 /* registry and global metatables may be changed by API */
|
|
|
993 markvalue(g, &g->l_registry);
|
|
|
994 markmt(g); /* mark basic metatables */
|
|
|
995 /* remark occasional upvalues of (maybe) dead threads */
|
|
|
996 remarkupvals(g);
|
|
|
997 propagateall(g); /* propagate changes */
|
|
|
998 work += g->GCmemtrav; /* stop counting (do not (re)count grays) */
|
|
|
999 /* traverse objects caught by write barrier and by 'remarkupvals' */
|
|
|
1000 retraversegrays(g);
|
|
|
1001 work -= g->GCmemtrav; /* restart counting */
|
|
|
1002 convergeephemerons(g);
|
|
|
1003 /* at this point, all strongly accessible objects are marked. */
|
|
|
1004 /* clear values from weak tables, before checking finalizers */
|
|
|
1005 clearvalues(g, g->weak, NULL);
|
|
|
1006 clearvalues(g, g->allweak, NULL);
|
|
|
1007 origweak = g->weak; origall = g->allweak;
|
|
|
1008 work += g->GCmemtrav; /* stop counting (objects being finalized) */
|
|
|
1009 separatetobefnz(L, 0); /* separate objects to be finalized */
|
|
|
1010 markbeingfnz(g); /* mark objects that will be finalized */
|
|
|
1011 propagateall(g); /* remark, to propagate `preserveness' */
|
|
|
1012 work -= g->GCmemtrav; /* restart counting */
|
|
|
1013 convergeephemerons(g);
|
|
|
1014 /* at this point, all resurrected objects are marked. */
|
|
|
1015 /* remove dead objects from weak tables */
|
|
|
1016 clearkeys(g, g->ephemeron, NULL); /* clear keys from all ephemeron tables */
|
|
|
1017 clearkeys(g, g->allweak, NULL); /* clear keys from all allweak tables */
|
|
|
1018 /* clear values from resurrected weak tables */
|
|
|
1019 clearvalues(g, g->weak, origweak);
|
|
|
1020 clearvalues(g, g->allweak, origall);
|
|
|
1021 g->currentwhite = cast_byte(otherwhite(g)); /* flip current white */
|
|
|
1022 work += g->GCmemtrav; /* complete counting */
|
|
|
1023 return work; /* estimate of memory marked by 'atomic' */
|
|
|
1024 }
|
|
|
1025
|
|
|
1026
|
|
|
1027 static lu_mem singlestep (lua_State *L) {
|
|
|
1028 global_State *g = G(L);
|
|
|
1029 switch (g->gcstate) {
|
|
|
1030 case GCSpause: {
|
|
|
1031 g->GCmemtrav = 0; /* start to count memory traversed */
|
|
|
1032 if (!isgenerational(g))
|
|
|
1033 markroot(g); /* start a new collection */
|
|
|
1034 /* in any case, root must be marked at this point */
|
|
|
1035 lua_assert(!iswhite(obj2gco(g->mainthread))
|
|
|
1036 && !iswhite(gcvalue(&g->l_registry)));
|
|
|
1037 g->gcstate = GCSpropagate;
|
|
|
1038 return g->GCmemtrav;
|
|
|
1039 }
|
|
|
1040 case GCSpropagate: {
|
|
|
1041 if (g->gray) {
|
|
|
1042 lu_mem oldtrav = g->GCmemtrav;
|
|
|
1043 propagatemark(g);
|
|
|
1044 return g->GCmemtrav - oldtrav; /* memory traversed in this step */
|
|
|
1045 }
|
|
|
1046 else { /* no more `gray' objects */
|
|
|
1047 lu_mem work;
|
|
|
1048 int sw;
|
|
|
1049 g->gcstate = GCSatomic; /* finish mark phase */
|
|
|
1050 g->GCestimate = g->GCmemtrav; /* save what was counted */;
|
|
|
1051 work = atomic(L); /* add what was traversed by 'atomic' */
|
|
|
1052 g->GCestimate += work; /* estimate of total memory traversed */
|
|
|
1053 sw = entersweep(L);
|
|
|
1054 return work + sw * GCSWEEPCOST;
|
|
|
1055 }
|
|
|
1056 }
|
|
|
1057 case GCSsweepstring: {
|
|
|
1058 int i;
|
|
|
1059 for (i = 0; i < GCSWEEPMAX && g->sweepstrgc + i < g->strt.size; i++)
|
|
|
1060 sweepwholelist(L, &g->strt.hash[g->sweepstrgc + i]);
|
|
|
1061 g->sweepstrgc += i;
|
|
|
1062 if (g->sweepstrgc >= g->strt.size) /* no more strings to sweep? */
|
|
|
1063 g->gcstate = GCSsweepudata;
|
|
|
1064 return i * GCSWEEPCOST;
|
|
|
1065 }
|
|
|
1066 case GCSsweepudata: {
|
|
|
1067 if (g->sweepfin) {
|
|
|
1068 g->sweepfin = sweeplist(L, g->sweepfin, GCSWEEPMAX);
|
|
|
1069 return GCSWEEPMAX*GCSWEEPCOST;
|
|
|
1070 }
|
|
|
1071 else {
|
|
|
1072 g->gcstate = GCSsweep;
|
|
|
1073 return 0;
|
|
|
1074 }
|
|
|
1075 }
|
|
|
1076 case GCSsweep: {
|
|
|
1077 if (g->sweepgc) {
|
|
|
1078 g->sweepgc = sweeplist(L, g->sweepgc, GCSWEEPMAX);
|
|
|
1079 return GCSWEEPMAX*GCSWEEPCOST;
|
|
|
1080 }
|
|
|
1081 else {
|
|
|
1082 /* sweep main thread */
|
|
|
1083 GCObject *mt = obj2gco(g->mainthread);
|
|
|
1084 sweeplist(L, &mt, 1);
|
|
|
1085 checkSizes(L);
|
|
|
1086 g->gcstate = GCSpause; /* finish collection */
|
|
|
1087 return GCSWEEPCOST;
|
|
|
1088 }
|
|
|
1089 }
|
|
|
1090 default: lua_assert(0); return 0;
|
|
|
1091 }
|
|
|
1092 }
|
|
|
1093
|
|
|
1094
|
|
|
1095 /*
|
|
|
1096 ** advances the garbage collector until it reaches a state allowed
|
|
|
1097 ** by 'statemask'
|
|
|
1098 */
|
|
|
1099 void luaC_runtilstate (lua_State *L, int statesmask) {
|
|
|
1100 global_State *g = G(L);
|
|
|
1101 while (!testbit(statesmask, g->gcstate))
|
|
|
1102 singlestep(L);
|
|
|
1103 }
|
|
|
1104
|
|
|
1105
|
|
|
1106 static void generationalcollection (lua_State *L) {
|
|
|
1107 global_State *g = G(L);
|
|
|
1108 if (g->GCestimate == 0) { /* signal for another major collection? */
|
|
|
1109 luaC_fullgc(L, 0); /* perform a full regular collection */
|
|
|
1110 g->GCestimate = gettotalbytes(g); /* update control */
|
|
|
1111 }
|
|
|
1112 else {
|
|
|
1113 lu_mem estimate = g->GCestimate;
|
|
|
1114 luaC_runtilstate(L, ~bitmask(GCSpause)); /* run complete cycle */
|
|
|
1115 luaC_runtilstate(L, bitmask(GCSpause));
|
|
|
1116 if (gettotalbytes(g) > (estimate / 100) * g->gcmajorinc)
|
|
|
1117 g->GCestimate = 0; /* signal for a major collection */
|
|
|
1118 }
|
|
|
1119 luaE_setdebt(g, stddebt(g));
|
|
|
1120 }
|
|
|
1121
|
|
|
1122
|
|
|
1123 static void incstep (lua_State *L) {
|
|
|
1124 global_State *g = G(L);
|
|
|
1125 l_mem debt = g->GCdebt;
|
|
|
1126 int stepmul = g->gcstepmul;
|
|
|
1127 if (stepmul < 40) stepmul = 40; /* avoid ridiculous low values */
|
|
|
1128 /* convert debt from Kb to 'work units' (avoid zero debt and overflows) */
|
|
|
1129 debt = (debt / STEPMULADJ) + 1;
|
|
|
1130 debt = (debt < MAX_LMEM / stepmul) ? debt * stepmul : MAX_LMEM;
|
|
|
1131 do { /* always perform at least one single step */
|
|
|
1132 lu_mem work = singlestep(L); /* do some work */
|
|
|
1133 debt -= work;
|
|
|
1134 } while (debt > -GCSTEPSIZE && g->gcstate != GCSpause);
|
|
|
1135 if (g->gcstate == GCSpause)
|
|
|
1136 debt = stddebtest(g, g->GCestimate); /* pause until next cycle */
|
|
|
1137 else
|
|
|
1138 debt = (debt / stepmul) * STEPMULADJ; /* convert 'work units' to Kb */
|
|
|
1139 luaE_setdebt(g, debt);
|
|
|
1140 }
|
|
|
1141
|
|
|
1142
|
|
|
1143 /*
|
|
|
1144 ** performs a basic GC step
|
|
|
1145 */
|
|
|
1146 void luaC_forcestep (lua_State *L) {
|
|
|
1147 global_State *g = G(L);
|
|
|
1148 int i;
|
|
|
1149 if (isgenerational(g)) generationalcollection(L);
|
|
|
1150 else incstep(L);
|
|
|
1151 /* run a few finalizers (or all of them at the end of a collect cycle) */
|
|
|
1152 for (i = 0; g->tobefnz && (i < GCFINALIZENUM || g->gcstate == GCSpause); i++)
|
|
|
1153 GCTM(L, 1); /* call one finalizer */
|
|
|
1154 }
|
|
|
1155
|
|
|
1156
|
|
|
1157 /*
|
|
|
1158 ** performs a basic GC step only if collector is running
|
|
|
1159 */
|
|
|
1160 void luaC_step (lua_State *L) {
|
|
|
1161 global_State *g = G(L);
|
|
|
1162 if (g->gcrunning) luaC_forcestep(L);
|
|
|
1163 else luaE_setdebt(g, -GCSTEPSIZE); /* avoid being called too often */
|
|
|
1164 }
|
|
|
1165
|
|
|
1166
|
|
|
1167
|
|
|
1168 /*
|
|
|
1169 ** performs a full GC cycle; if "isemergency", does not call
|
|
|
1170 ** finalizers (which could change stack positions)
|
|
|
1171 */
|
|
|
1172 void luaC_fullgc (lua_State *L, int isemergency) {
|
|
|
1173 global_State *g = G(L);
|
|
|
1174 int origkind = g->gckind;
|
|
|
1175 int someblack = keepinvariant(g);
|
|
|
1176 lua_assert(origkind != KGC_EMERGENCY);
|
|
|
1177 if (isemergency) /* do not run finalizers during emergency GC */
|
|
|
1178 g->gckind = KGC_EMERGENCY;
|
|
|
1179 else {
|
|
|
1180 g->gckind = KGC_NORMAL;
|
|
|
1181 callallpendingfinalizers(L, 1);
|
|
|
1182 }
|
|
|
1183 if (someblack) { /* may there be some black objects? */
|
|
|
1184 /* must sweep all objects to turn them back to white
|
|
|
1185 (as white has not changed, nothing will be collected) */
|
|
|
1186 entersweep(L);
|
|
|
1187 }
|
|
|
1188 /* finish any pending sweep phase to start a new cycle */
|
|
|
1189 luaC_runtilstate(L, bitmask(GCSpause));
|
|
|
1190 /* run entire collector */
|
|
|
1191 luaC_runtilstate(L, ~bitmask(GCSpause));
|
|
|
1192 luaC_runtilstate(L, bitmask(GCSpause));
|
|
|
1193 if (origkind == KGC_GEN) { /* generational mode? */
|
|
|
1194 /* generational mode must always start in propagate phase */
|
|
|
1195 luaC_runtilstate(L, bitmask(GCSpropagate));
|
|
|
1196 }
|
|
|
1197 g->gckind = origkind;
|
|
|
1198 luaE_setdebt(g, stddebt(g));
|
|
|
1199 if (!isemergency) /* do not run finalizers during emergency GC */
|
|
|
1200 callallpendingfinalizers(L, 1);
|
|
|
1201 }
|
|
|
1202
|
|
|
1203 /* }====================================================== */
|
|
|
1204
|
|
|
1205
|
