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1866
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1 /*
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2 ** $Id: lgc.c,v 2.140 2013/03/16 21:10:18 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 /*
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48 ** macro to adjust 'pause': 'pause' is actually used like
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49 ** 'pause / PAUSEADJ' (value chosen by tests)
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50 */
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51 #define PAUSEADJ 100
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52
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53
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54 /*
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55 ** 'makewhite' erases all color bits plus the old bit and then
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56 ** sets only the current white bit
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57 */
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58 #define maskcolors (~(bit2mask(BLACKBIT, OLDBIT) | WHITEBITS))
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59 #define makewhite(g,x) \
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60 (gch(x)->marked = cast_byte((gch(x)->marked & maskcolors) | luaC_white(g)))
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61
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62 #define white2gray(x) resetbits(gch(x)->marked, WHITEBITS)
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63 #define black2gray(x) resetbit(gch(x)->marked, BLACKBIT)
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64
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65
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66 #define isfinalized(x) testbit(gch(x)->marked, FINALIZEDBIT)
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67
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68 #define checkdeadkey(n) lua_assert(!ttisdeadkey(gkey(n)) || ttisnil(gval(n)))
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69
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70
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71 #define checkconsistency(obj) \
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72 lua_longassert(!iscollectable(obj) || righttt(obj))
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73
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74
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75 #define markvalue(g,o) { checkconsistency(o); \
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76 if (valiswhite(o)) reallymarkobject(g,gcvalue(o)); }
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77
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78 #define markobject(g,t) { if ((t) && iswhite(obj2gco(t))) \
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79 reallymarkobject(g, obj2gco(t)); }
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80
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81 static void reallymarkobject (global_State *g, GCObject *o);
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82
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83
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84 /*
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85 ** {======================================================
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86 ** Generic functions
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87 ** =======================================================
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88 */
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89
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90
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91 /*
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92 ** one after last element in a hash array
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93 */
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94 #define gnodelast(h) gnode(h, cast(size_t, sizenode(h)))
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95
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96
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97 /*
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98 ** link table 'h' into list pointed by 'p'
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99 */
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100 #define linktable(h,p) ((h)->gclist = *(p), *(p) = obj2gco(h))
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101
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102
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103 /*
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104 ** if key is not marked, mark its entry as dead (therefore removing it
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105 ** from the table)
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106 */
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107 static void removeentry (Node *n) {
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108 lua_assert(ttisnil(gval(n)));
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109 if (valiswhite(gkey(n)))
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110 setdeadvalue(gkey(n)); /* unused and unmarked key; remove it */
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111 }
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112
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113
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114 /*
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115 ** tells whether a key or value can be cleared from a weak
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116 ** table. Non-collectable objects are never removed from weak
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117 ** tables. Strings behave as `values', so are never removed too. for
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118 ** other objects: if really collected, cannot keep them; for objects
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119 ** being finalized, keep them in keys, but not in values
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120 */
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121 static int iscleared (global_State *g, const TValue *o) {
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122 if (!iscollectable(o)) return 0;
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123 else if (ttisstring(o)) {
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124 markobject(g, rawtsvalue(o)); /* strings are `values', so are never weak */
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125 return 0;
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126 }
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127 else return iswhite(gcvalue(o));
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128 }
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129
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130
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131 /*
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132 ** barrier that moves collector forward, that is, mark the white object
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133 ** being pointed by a black object.
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134 */
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135 void luaC_barrier_ (lua_State *L, GCObject *o, GCObject *v) {
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136 global_State *g = G(L);
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137 lua_assert(isblack(o) && iswhite(v) && !isdead(g, v) && !isdead(g, o));
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138 lua_assert(g->gcstate != GCSpause);
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139 lua_assert(gch(o)->tt != LUA_TTABLE);
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140 if (keepinvariantout(g)) /* must keep invariant? */
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141 reallymarkobject(g, v); /* restore invariant */
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142 else { /* sweep phase */
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143 lua_assert(issweepphase(g));
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144 makewhite(g, o); /* mark main obj. as white to avoid other barriers */
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145 }
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146 }
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147
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148
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149 /*
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150 ** barrier that moves collector backward, that is, mark the black object
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151 ** pointing to a white object as gray again. (Current implementation
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152 ** only works for tables; access to 'gclist' is not uniform across
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153 ** different types.)
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154 */
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155 void luaC_barrierback_ (lua_State *L, GCObject *o) {
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156 global_State *g = G(L);
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157 lua_assert(isblack(o) && !isdead(g, o) && gch(o)->tt == LUA_TTABLE);
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158 black2gray(o); /* make object gray (again) */
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159 gco2t(o)->gclist = g->grayagain;
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160 g->grayagain = o;
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161 }
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162
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163
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164 /*
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165 ** barrier for prototypes. When creating first closure (cache is
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166 ** NULL), use a forward barrier; this may be the only closure of the
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167 ** prototype (if it is a "regular" function, with a single instance)
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168 ** and the prototype may be big, so it is better to avoid traversing
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169 ** it again. Otherwise, use a backward barrier, to avoid marking all
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170 ** possible instances.
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171 */
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172 LUAI_FUNC void luaC_barrierproto_ (lua_State *L, Proto *p, Closure *c) {
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173 global_State *g = G(L);
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174 lua_assert(isblack(obj2gco(p)));
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175 if (p->cache == NULL) { /* first time? */
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176 luaC_objbarrier(L, p, c);
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177 }
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178 else { /* use a backward barrier */
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179 black2gray(obj2gco(p)); /* make prototype gray (again) */
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180 p->gclist = g->grayagain;
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181 g->grayagain = obj2gco(p);
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182 }
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183 }
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184
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185
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186 /*
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187 ** check color (and invariants) for an upvalue that was closed,
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188 ** i.e., moved into the 'allgc' list
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189 */
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190 void luaC_checkupvalcolor (global_State *g, UpVal *uv) {
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191 GCObject *o = obj2gco(uv);
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192 lua_assert(!isblack(o)); /* open upvalues are never black */
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193 if (isgray(o)) {
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194 if (keepinvariant(g)) {
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195 resetoldbit(o); /* see MOVE OLD rule */
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196 gray2black(o); /* it is being visited now */
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197 markvalue(g, uv->v);
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198 }
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199 else {
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200 lua_assert(issweepphase(g));
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201 makewhite(g, o);
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202 }
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203 }
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204 }
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205
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206
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207 /*
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208 ** create a new collectable object (with given type and size) and link
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209 ** it to '*list'. 'offset' tells how many bytes to allocate before the
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210 ** object itself (used only by states).
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211 */
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212 GCObject *luaC_newobj (lua_State *L, int tt, size_t sz, GCObject **list,
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213 int offset) {
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214 global_State *g = G(L);
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215 char *raw = cast(char *, luaM_newobject(L, novariant(tt), sz));
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216 GCObject *o = obj2gco(raw + offset);
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217 if (list == NULL)
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218 list = &g->allgc; /* standard list for collectable objects */
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219 gch(o)->marked = luaC_white(g);
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220 gch(o)->tt = tt;
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221 gch(o)->next = *list;
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222 *list = o;
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223 return o;
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224 }
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225
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226 /* }====================================================== */
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227
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228
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229
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230 /*
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231 ** {======================================================
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232 ** Mark functions
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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 ** mark an object. Userdata, strings, and closed upvalues are visited
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239 ** and turned black here. Other objects are marked gray and added
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240 ** to appropriate list to be visited (and turned black) later. (Open
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241 ** upvalues are already linked in 'headuv' list.)
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242 */
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243 static void reallymarkobject (global_State *g, GCObject *o) {
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244 lu_mem size;
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245 white2gray(o);
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246 switch (gch(o)->tt) {
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247 case LUA_TSHRSTR:
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248 case LUA_TLNGSTR: {
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249 size = sizestring(gco2ts(o));
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250 break; /* nothing else to mark; make it black */
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251 }
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252 case LUA_TUSERDATA: {
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253 Table *mt = gco2u(o)->metatable;
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254 markobject(g, mt);
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255 markobject(g, gco2u(o)->env);
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256 size = sizeudata(gco2u(o));
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257 break;
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258 }
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259 case LUA_TUPVAL: {
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260 UpVal *uv = gco2uv(o);
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261 markvalue(g, uv->v);
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262 if (uv->v != &uv->u.value) /* open? */
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263 return; /* open upvalues remain gray */
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264 size = sizeof(UpVal);
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265 break;
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266 }
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267 case LUA_TLCL: {
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268 gco2lcl(o)->gclist = g->gray;
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269 g->gray = o;
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270 return;
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271 }
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272 case LUA_TCCL: {
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273 gco2ccl(o)->gclist = g->gray;
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274 g->gray = o;
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275 return;
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276 }
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277 case LUA_TTABLE: {
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278 linktable(gco2t(o), &g->gray);
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279 return;
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280 }
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281 case LUA_TTHREAD: {
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282 gco2th(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_TPROTO: {
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287 gco2p(o)->gclist = g->gray;
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288 g->gray = o;
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289 return;
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290 }
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291 default: lua_assert(0); return;
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292 }
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293 gray2black(o);
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294 g->GCmemtrav += size;
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295 }
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296
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297
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298 /*
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299 ** mark metamethods for basic types
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300 */
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301 static void markmt (global_State *g) {
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302 int i;
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303 for (i=0; i < LUA_NUMTAGS; i++)
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304 markobject(g, g->mt[i]);
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305 }
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306
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307
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308 /*
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309 ** mark all objects in list of being-finalized
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310 */
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311 static void markbeingfnz (global_State *g) {
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312 GCObject *o;
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313 for (o = g->tobefnz; o != NULL; o = gch(o)->next) {
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314 makewhite(g, o);
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315 reallymarkobject(g, o);
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316 }
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317 }
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318
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319
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320 /*
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321 ** mark all values stored in marked open upvalues. (See comment in
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322 ** 'lstate.h'.)
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323 */
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324 static void remarkupvals (global_State *g) {
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325 UpVal *uv;
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326 for (uv = g->uvhead.u.l.next; uv != &g->uvhead; uv = uv->u.l.next) {
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327 if (isgray(obj2gco(uv)))
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328 markvalue(g, uv->v);
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329 }
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330 }
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331
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332
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333 /*
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334 ** mark root set and reset all gray lists, to start a new
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335 ** incremental (or full) collection
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336 */
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337 static void restartcollection (global_State *g) {
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338 g->gray = g->grayagain = NULL;
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339 g->weak = g->allweak = g->ephemeron = NULL;
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340 markobject(g, g->mainthread);
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341 markvalue(g, &g->l_registry);
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342 markmt(g);
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343 markbeingfnz(g); /* mark any finalizing object left from previous cycle */
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344 }
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345
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346 /* }====================================================== */
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347
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348
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349 /*
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350 ** {======================================================
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351 ** Traverse functions
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352 ** =======================================================
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353 */
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354
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355 static void traverseweakvalue (global_State *g, Table *h) {
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356 Node *n, *limit = gnodelast(h);
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357 /* if there is array part, assume it may have white values (do not
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358 traverse it just to check) */
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359 int hasclears = (h->sizearray > 0);
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360 for (n = gnode(h, 0); n < limit; n++) {
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361 checkdeadkey(n);
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362 if (ttisnil(gval(n))) /* entry is empty? */
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363 removeentry(n); /* remove it */
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364 else {
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365 lua_assert(!ttisnil(gkey(n)));
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366 markvalue(g, gkey(n)); /* mark key */
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367 if (!hasclears && iscleared(g, gval(n))) /* is there a white value? */
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368 hasclears = 1; /* table will have to be cleared */
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369 }
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370 }
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371 if (hasclears)
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372 linktable(h, &g->weak); /* has to be cleared later */
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373 else /* no white values */
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374 linktable(h, &g->grayagain); /* no need to clean */
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375 }
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376
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377
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378 static int traverseephemeron (global_State *g, Table *h) {
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379 int marked = 0; /* true if an object is marked in this traversal */
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380 int hasclears = 0; /* true if table has white keys */
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381 int prop = 0; /* true if table has entry "white-key -> white-value" */
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382 Node *n, *limit = gnodelast(h);
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383 int i;
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384 /* traverse array part (numeric keys are 'strong') */
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385 for (i = 0; i < h->sizearray; i++) {
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386 if (valiswhite(&h->array[i])) {
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387 marked = 1;
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388 reallymarkobject(g, gcvalue(&h->array[i]));
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389 }
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390 }
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391 /* traverse hash part */
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392 for (n = gnode(h, 0); n < limit; n++) {
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393 checkdeadkey(n);
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394 if (ttisnil(gval(n))) /* entry is empty? */
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395 removeentry(n); /* remove it */
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396 else if (iscleared(g, gkey(n))) { /* key is not marked (yet)? */
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397 hasclears = 1; /* table must be cleared */
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398 if (valiswhite(gval(n))) /* value not marked yet? */
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399 prop = 1; /* must propagate again */
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400 }
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401 else if (valiswhite(gval(n))) { /* value not marked yet? */
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402 marked = 1;
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403 reallymarkobject(g, gcvalue(gval(n))); /* mark it now */
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404 }
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405 }
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406 if (prop)
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407 linktable(h, &g->ephemeron); /* have to propagate again */
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408 else if (hasclears) /* does table have white keys? */
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|
409 linktable(h, &g->allweak); /* may have to clean white keys */
|
|
|
410 else /* no white keys */
|
|
|
411 linktable(h, &g->grayagain); /* no need to clean */
|
|
|
412 return marked;
|
|
|
413 }
|
|
|
414
|
|
|
415
|
|
|
416 static void traversestrongtable (global_State *g, Table *h) {
|
|
|
417 Node *n, *limit = gnodelast(h);
|
|
|
418 int i;
|
|
|
419 for (i = 0; i < h->sizearray; i++) /* traverse array part */
|
|
|
420 markvalue(g, &h->array[i]);
|
|
|
421 for (n = gnode(h, 0); n < limit; n++) { /* traverse hash part */
|
|
|
422 checkdeadkey(n);
|
|
|
423 if (ttisnil(gval(n))) /* entry is empty? */
|
|
|
424 removeentry(n); /* remove it */
|
|
|
425 else {
|
|
|
426 lua_assert(!ttisnil(gkey(n)));
|
|
|
427 markvalue(g, gkey(n)); /* mark key */
|
|
|
428 markvalue(g, gval(n)); /* mark value */
|
|
|
429 }
|
|
|
430 }
|
|
|
431 }
|
|
|
432
|
|
|
433
|
|
|
434 static lu_mem traversetable (global_State *g, Table *h) {
|
|
|
435 const char *weakkey, *weakvalue;
|
|
|
436 const TValue *mode = gfasttm(g, h->metatable, TM_MODE);
|
|
|
437 markobject(g, h->metatable);
|
|
|
438 if (mode && ttisstring(mode) && /* is there a weak mode? */
|
|
|
439 ((weakkey = strchr(svalue(mode), 'k')),
|
|
|
440 (weakvalue = strchr(svalue(mode), 'v')),
|
|
|
441 (weakkey || weakvalue))) { /* is really weak? */
|
|
|
442 black2gray(obj2gco(h)); /* keep table gray */
|
|
|
443 if (!weakkey) /* strong keys? */
|
|
|
444 traverseweakvalue(g, h);
|
|
|
445 else if (!weakvalue) /* strong values? */
|
|
|
446 traverseephemeron(g, h);
|
|
|
447 else /* all weak */
|
|
|
448 linktable(h, &g->allweak); /* nothing to traverse now */
|
|
|
449 }
|
|
|
450 else /* not weak */
|
|
|
451 traversestrongtable(g, h);
|
|
|
452 return sizeof(Table) + sizeof(TValue) * h->sizearray +
|
|
|
453 sizeof(Node) * cast(size_t, sizenode(h));
|
|
|
454 }
|
|
|
455
|
|
|
456
|
|
|
457 static int traverseproto (global_State *g, Proto *f) {
|
|
|
458 int i;
|
|
|
459 if (f->cache && iswhite(obj2gco(f->cache)))
|
|
|
460 f->cache = NULL; /* allow cache to be collected */
|
|
|
461 markobject(g, f->source);
|
|
|
462 for (i = 0; i < f->sizek; i++) /* mark literals */
|
|
|
463 markvalue(g, &f->k[i]);
|
|
|
464 for (i = 0; i < f->sizeupvalues; i++) /* mark upvalue names */
|
|
|
465 markobject(g, f->upvalues[i].name);
|
|
|
466 for (i = 0; i < f->sizep; i++) /* mark nested protos */
|
|
|
467 markobject(g, f->p[i]);
|
|
|
468 for (i = 0; i < f->sizelocvars; i++) /* mark local-variable names */
|
|
|
469 markobject(g, f->locvars[i].varname);
|
|
|
470 return sizeof(Proto) + sizeof(Instruction) * f->sizecode +
|
|
|
471 sizeof(Proto *) * f->sizep +
|
|
|
472 sizeof(TValue) * f->sizek +
|
|
|
473 sizeof(int) * f->sizelineinfo +
|
|
|
474 sizeof(LocVar) * f->sizelocvars +
|
|
|
475 sizeof(Upvaldesc) * f->sizeupvalues;
|
|
|
476 }
|
|
|
477
|
|
|
478
|
|
|
479 static lu_mem traverseCclosure (global_State *g, CClosure *cl) {
|
|
|
480 int i;
|
|
|
481 for (i = 0; i < cl->nupvalues; i++) /* mark its upvalues */
|
|
|
482 markvalue(g, &cl->upvalue[i]);
|
|
|
483 return sizeCclosure(cl->nupvalues);
|
|
|
484 }
|
|
|
485
|
|
|
486 static lu_mem traverseLclosure (global_State *g, LClosure *cl) {
|
|
|
487 int i;
|
|
|
488 markobject(g, cl->p); /* mark its prototype */
|
|
|
489 for (i = 0; i < cl->nupvalues; i++) /* mark its upvalues */
|
|
|
490 markobject(g, cl->upvals[i]);
|
|
|
491 return sizeLclosure(cl->nupvalues);
|
|
|
492 }
|
|
|
493
|
|
|
494
|
|
|
495 static lu_mem traversestack (global_State *g, lua_State *th) {
|
|
|
496 StkId o = th->stack;
|
|
|
497 if (o == NULL)
|
|
|
498 return 1; /* stack not completely built yet */
|
|
|
499 for (; o < th->top; o++)
|
|
|
500 markvalue(g, o);
|
|
|
501 if (g->gcstate == GCSatomic) { /* final traversal? */
|
|
|
502 StkId lim = th->stack + th->stacksize; /* real end of stack */
|
|
|
503 for (; o < lim; o++) /* clear not-marked stack slice */
|
|
|
504 setnilvalue(o);
|
|
|
505 }
|
|
|
506 return sizeof(lua_State) + sizeof(TValue) * th->stacksize;
|
|
|
507 }
|
|
|
508
|
|
|
509
|
|
|
510 /*
|
|
|
511 ** traverse one gray object, turning it to black (except for threads,
|
|
|
512 ** which are always gray).
|
|
|
513 */
|
|
|
514 static void propagatemark (global_State *g) {
|
|
|
515 lu_mem size;
|
|
|
516 GCObject *o = g->gray;
|
|
|
517 lua_assert(isgray(o));
|
|
|
518 gray2black(o);
|
|
|
519 switch (gch(o)->tt) {
|
|
|
520 case LUA_TTABLE: {
|
|
|
521 Table *h = gco2t(o);
|
|
|
522 g->gray = h->gclist; /* remove from 'gray' list */
|
|
|
523 size = traversetable(g, h);
|
|
|
524 break;
|
|
|
525 }
|
|
|
526 case LUA_TLCL: {
|
|
|
527 LClosure *cl = gco2lcl(o);
|
|
|
528 g->gray = cl->gclist; /* remove from 'gray' list */
|
|
|
529 size = traverseLclosure(g, cl);
|
|
|
530 break;
|
|
|
531 }
|
|
|
532 case LUA_TCCL: {
|
|
|
533 CClosure *cl = gco2ccl(o);
|
|
|
534 g->gray = cl->gclist; /* remove from 'gray' list */
|
|
|
535 size = traverseCclosure(g, cl);
|
|
|
536 break;
|
|
|
537 }
|
|
|
538 case LUA_TTHREAD: {
|
|
|
539 lua_State *th = gco2th(o);
|
|
|
540 g->gray = th->gclist; /* remove from 'gray' list */
|
|
|
541 th->gclist = g->grayagain;
|
|
|
542 g->grayagain = o; /* insert into 'grayagain' list */
|
|
|
543 black2gray(o);
|
|
|
544 size = traversestack(g, th);
|
|
|
545 break;
|
|
|
546 }
|
|
|
547 case LUA_TPROTO: {
|
|
|
548 Proto *p = gco2p(o);
|
|
|
549 g->gray = p->gclist; /* remove from 'gray' list */
|
|
|
550 size = traverseproto(g, p);
|
|
|
551 break;
|
|
|
552 }
|
|
|
553 default: lua_assert(0); return;
|
|
|
554 }
|
|
|
555 g->GCmemtrav += size;
|
|
|
556 }
|
|
|
557
|
|
|
558
|
|
|
559 static void propagateall (global_State *g) {
|
|
|
560 while (g->gray) propagatemark(g);
|
|
|
561 }
|
|
|
562
|
|
|
563
|
|
|
564 static void propagatelist (global_State *g, GCObject *l) {
|
|
|
565 lua_assert(g->gray == NULL); /* no grays left */
|
|
|
566 g->gray = l;
|
|
|
567 propagateall(g); /* traverse all elements from 'l' */
|
|
|
568 }
|
|
|
569
|
|
|
570 /*
|
|
|
571 ** retraverse all gray lists. Because tables may be reinserted in other
|
|
|
572 ** lists when traversed, traverse the original lists to avoid traversing
|
|
|
573 ** twice the same table (which is not wrong, but inefficient)
|
|
|
574 */
|
|
|
575 static void retraversegrays (global_State *g) {
|
|
|
576 GCObject *weak = g->weak; /* save original lists */
|
|
|
577 GCObject *grayagain = g->grayagain;
|
|
|
578 GCObject *ephemeron = g->ephemeron;
|
|
|
579 g->weak = g->grayagain = g->ephemeron = NULL;
|
|
|
580 propagateall(g); /* traverse main gray list */
|
|
|
581 propagatelist(g, grayagain);
|
|
|
582 propagatelist(g, weak);
|
|
|
583 propagatelist(g, ephemeron);
|
|
|
584 }
|
|
|
585
|
|
|
586
|
|
|
587 static void convergeephemerons (global_State *g) {
|
|
|
588 int changed;
|
|
|
589 do {
|
|
|
590 GCObject *w;
|
|
|
591 GCObject *next = g->ephemeron; /* get ephemeron list */
|
|
|
592 g->ephemeron = NULL; /* tables will return to this list when traversed */
|
|
|
593 changed = 0;
|
|
|
594 while ((w = next) != NULL) {
|
|
|
595 next = gco2t(w)->gclist;
|
|
|
596 if (traverseephemeron(g, gco2t(w))) { /* traverse marked some value? */
|
|
|
597 propagateall(g); /* propagate changes */
|
|
|
598 changed = 1; /* will have to revisit all ephemeron tables */
|
|
|
599 }
|
|
|
600 }
|
|
|
601 } while (changed);
|
|
|
602 }
|
|
|
603
|
|
|
604 /* }====================================================== */
|
|
|
605
|
|
|
606
|
|
|
607 /*
|
|
|
608 ** {======================================================
|
|
|
609 ** Sweep Functions
|
|
|
610 ** =======================================================
|
|
|
611 */
|
|
|
612
|
|
|
613
|
|
|
614 /*
|
|
|
615 ** clear entries with unmarked keys from all weaktables in list 'l' up
|
|
|
616 ** to element 'f'
|
|
|
617 */
|
|
|
618 static void clearkeys (global_State *g, GCObject *l, GCObject *f) {
|
|
|
619 for (; l != f; l = gco2t(l)->gclist) {
|
|
|
620 Table *h = gco2t(l);
|
|
|
621 Node *n, *limit = gnodelast(h);
|
|
|
622 for (n = gnode(h, 0); n < limit; n++) {
|
|
|
623 if (!ttisnil(gval(n)) && (iscleared(g, gkey(n)))) {
|
|
|
624 setnilvalue(gval(n)); /* remove value ... */
|
|
|
625 removeentry(n); /* and remove entry from table */
|
|
|
626 }
|
|
|
627 }
|
|
|
628 }
|
|
|
629 }
|
|
|
630
|
|
|
631
|
|
|
632 /*
|
|
|
633 ** clear entries with unmarked values from all weaktables in list 'l' up
|
|
|
634 ** to element 'f'
|
|
|
635 */
|
|
|
636 static void clearvalues (global_State *g, GCObject *l, GCObject *f) {
|
|
|
637 for (; l != f; l = gco2t(l)->gclist) {
|
|
|
638 Table *h = gco2t(l);
|
|
|
639 Node *n, *limit = gnodelast(h);
|
|
|
640 int i;
|
|
|
641 for (i = 0; i < h->sizearray; i++) {
|
|
|
642 TValue *o = &h->array[i];
|
|
|
643 if (iscleared(g, o)) /* value was collected? */
|
|
|
644 setnilvalue(o); /* remove value */
|
|
|
645 }
|
|
|
646 for (n = gnode(h, 0); n < limit; n++) {
|
|
|
647 if (!ttisnil(gval(n)) && iscleared(g, gval(n))) {
|
|
|
648 setnilvalue(gval(n)); /* remove value ... */
|
|
|
649 removeentry(n); /* and remove entry from table */
|
|
|
650 }
|
|
|
651 }
|
|
|
652 }
|
|
|
653 }
|
|
|
654
|
|
|
655
|
|
|
656 static void freeobj (lua_State *L, GCObject *o) {
|
|
|
657 switch (gch(o)->tt) {
|
|
|
658 case LUA_TPROTO: luaF_freeproto(L, gco2p(o)); break;
|
|
|
659 case LUA_TLCL: {
|
|
|
660 luaM_freemem(L, o, sizeLclosure(gco2lcl(o)->nupvalues));
|
|
|
661 break;
|
|
|
662 }
|
|
|
663 case LUA_TCCL: {
|
|
|
664 luaM_freemem(L, o, sizeCclosure(gco2ccl(o)->nupvalues));
|
|
|
665 break;
|
|
|
666 }
|
|
|
667 case LUA_TUPVAL: luaF_freeupval(L, gco2uv(o)); break;
|
|
|
668 case LUA_TTABLE: luaH_free(L, gco2t(o)); break;
|
|
|
669 case LUA_TTHREAD: luaE_freethread(L, gco2th(o)); break;
|
|
|
670 case LUA_TUSERDATA: luaM_freemem(L, o, sizeudata(gco2u(o))); break;
|
|
|
671 case LUA_TSHRSTR:
|
|
|
672 G(L)->strt.nuse--;
|
|
|
673 /* go through */
|
|
|
674 case LUA_TLNGSTR: {
|
|
|
675 luaM_freemem(L, o, sizestring(gco2ts(o)));
|
|
|
676 break;
|
|
|
677 }
|
|
|
678 default: lua_assert(0);
|
|
|
679 }
|
|
|
680 }
|
|
|
681
|
|
|
682
|
|
|
683 #define sweepwholelist(L,p) sweeplist(L,p,MAX_LUMEM)
|
|
|
684 static GCObject **sweeplist (lua_State *L, GCObject **p, lu_mem count);
|
|
|
685
|
|
|
686
|
|
|
687 /*
|
|
|
688 ** sweep the (open) upvalues of a thread and resize its stack and
|
|
|
689 ** list of call-info structures.
|
|
|
690 */
|
|
|
691 static void sweepthread (lua_State *L, lua_State *L1) {
|
|
|
692 if (L1->stack == NULL) return; /* stack not completely built yet */
|
|
|
693 sweepwholelist(L, &L1->openupval); /* sweep open upvalues */
|
|
|
694 luaE_freeCI(L1); /* free extra CallInfo slots */
|
|
|
695 /* should not change the stack during an emergency gc cycle */
|
|
|
696 if (G(L)->gckind != KGC_EMERGENCY)
|
|
|
697 luaD_shrinkstack(L1);
|
|
|
698 }
|
|
|
699
|
|
|
700
|
|
|
701 /*
|
|
|
702 ** sweep at most 'count' elements from a list of GCObjects erasing dead
|
|
|
703 ** objects, where a dead (not alive) object is one marked with the "old"
|
|
|
704 ** (non current) white and not fixed.
|
|
|
705 ** In non-generational mode, change all non-dead objects back to white,
|
|
|
706 ** preparing for next collection cycle.
|
|
|
707 ** In generational mode, keep black objects black, and also mark them as
|
|
|
708 ** old; stop when hitting an old object, as all objects after that
|
|
|
709 ** one will be old too.
|
|
|
710 ** When object is a thread, sweep its list of open upvalues too.
|
|
|
711 */
|
|
|
712 static GCObject **sweeplist (lua_State *L, GCObject **p, lu_mem count) {
|
|
|
713 global_State *g = G(L);
|
|
|
714 int ow = otherwhite(g);
|
|
|
715 int toclear, toset; /* bits to clear and to set in all live objects */
|
|
|
716 int tostop; /* stop sweep when this is true */
|
|
|
717 if (isgenerational(g)) { /* generational mode? */
|
|
|
718 toclear = ~0; /* clear nothing */
|
|
|
719 toset = bitmask(OLDBIT); /* set the old bit of all surviving objects */
|
|
|
720 tostop = bitmask(OLDBIT); /* do not sweep old generation */
|
|
|
721 }
|
|
|
722 else { /* normal mode */
|
|
|
723 toclear = maskcolors; /* clear all color bits + old bit */
|
|
|
724 toset = luaC_white(g); /* make object white */
|
|
|
725 tostop = 0; /* do not stop */
|
|
|
726 }
|
|
|
727 while (*p != NULL && count-- > 0) {
|
|
|
728 GCObject *curr = *p;
|
|
|
729 int marked = gch(curr)->marked;
|
|
|
730 if (isdeadm(ow, marked)) { /* is 'curr' dead? */
|
|
|
731 *p = gch(curr)->next; /* remove 'curr' from list */
|
|
|
732 freeobj(L, curr); /* erase 'curr' */
|
|
|
733 }
|
|
|
734 else {
|
|
|
735 if (testbits(marked, tostop))
|
|
|
736 return NULL; /* stop sweeping this list */
|
|
|
737 if (gch(curr)->tt == LUA_TTHREAD)
|
|
|
738 sweepthread(L, gco2th(curr)); /* sweep thread's upvalues */
|
|
|
739 /* update marks */
|
|
|
740 gch(curr)->marked = cast_byte((marked & toclear) | toset);
|
|
|
741 p = &gch(curr)->next; /* go to next element */
|
|
|
742 }
|
|
|
743 }
|
|
|
744 return (*p == NULL) ? NULL : p;
|
|
|
745 }
|
|
|
746
|
|
|
747
|
|
|
748 /*
|
|
|
749 ** sweep a list until a live object (or end of list)
|
|
|
750 */
|
|
|
751 static GCObject **sweeptolive (lua_State *L, GCObject **p, int *n) {
|
|
|
752 GCObject ** old = p;
|
|
|
753 int i = 0;
|
|
|
754 do {
|
|
|
755 i++;
|
|
|
756 p = sweeplist(L, p, 1);
|
|
|
757 } while (p == old);
|
|
|
758 if (n) *n += i;
|
|
|
759 return p;
|
|
|
760 }
|
|
|
761
|
|
|
762 /* }====================================================== */
|
|
|
763
|
|
|
764
|
|
|
765 /*
|
|
|
766 ** {======================================================
|
|
|
767 ** Finalization
|
|
|
768 ** =======================================================
|
|
|
769 */
|
|
|
770
|
|
|
771 static void checkSizes (lua_State *L) {
|
|
|
772 global_State *g = G(L);
|
|
|
773 if (g->gckind != KGC_EMERGENCY) { /* do not change sizes in emergency */
|
|
|
774 int hs = g->strt.size / 2; /* half the size of the string table */
|
|
|
775 if (g->strt.nuse < cast(lu_int32, hs)) /* using less than that half? */
|
|
|
776 luaS_resize(L, hs); /* halve its size */
|
|
|
777 luaZ_freebuffer(L, &g->buff); /* free concatenation buffer */
|
|
|
778 }
|
|
|
779 }
|
|
|
780
|
|
|
781
|
|
|
782 static GCObject *udata2finalize (global_State *g) {
|
|
|
783 GCObject *o = g->tobefnz; /* get first element */
|
|
|
784 lua_assert(isfinalized(o));
|
|
|
785 g->tobefnz = gch(o)->next; /* remove it from 'tobefnz' list */
|
|
|
786 gch(o)->next = g->allgc; /* return it to 'allgc' list */
|
|
|
787 g->allgc = o;
|
|
|
788 resetbit(gch(o)->marked, SEPARATED); /* mark that it is not in 'tobefnz' */
|
|
|
789 lua_assert(!isold(o)); /* see MOVE OLD rule */
|
|
|
790 if (!keepinvariantout(g)) /* not keeping invariant? */
|
|
|
791 makewhite(g, o); /* "sweep" object */
|
|
|
792 return o;
|
|
|
793 }
|
|
|
794
|
|
|
795
|
|
|
796 static void dothecall (lua_State *L, void *ud) {
|
|
|
797 UNUSED(ud);
|
|
|
798 luaD_call(L, L->top - 2, 0, 0);
|
|
|
799 }
|
|
|
800
|
|
|
801
|
|
|
802 static void GCTM (lua_State *L, int propagateerrors) {
|
|
|
803 global_State *g = G(L);
|
|
|
804 const TValue *tm;
|
|
|
805 TValue v;
|
|
|
806 setgcovalue(L, &v, udata2finalize(g));
|
|
|
807 tm = luaT_gettmbyobj(L, &v, TM_GC);
|
|
|
808 if (tm != NULL && ttisfunction(tm)) { /* is there a finalizer? */
|
|
|
809 int status;
|
|
|
810 lu_byte oldah = L->allowhook;
|
|
|
811 int running = g->gcrunning;
|
|
|
812 L->allowhook = 0; /* stop debug hooks during GC metamethod */
|
|
|
813 g->gcrunning = 0; /* avoid GC steps */
|
|
|
814 setobj2s(L, L->top, tm); /* push finalizer... */
|
|
|
815 setobj2s(L, L->top + 1, &v); /* ... and its argument */
|
|
|
816 L->top += 2; /* and (next line) call the finalizer */
|
|
|
817 status = luaD_pcall(L, dothecall, NULL, savestack(L, L->top - 2), 0);
|
|
|
818 L->allowhook = oldah; /* restore hooks */
|
|
|
819 g->gcrunning = running; /* restore state */
|
|
|
820 if (status != LUA_OK && propagateerrors) { /* error while running __gc? */
|
|
|
821 if (status == LUA_ERRRUN) { /* is there an error object? */
|
|
|
822 const char *msg = (ttisstring(L->top - 1))
|
|
|
823 ? svalue(L->top - 1)
|
|
|
824 : "no message";
|
|
|
825 luaO_pushfstring(L, "error in __gc metamethod (%s)", msg);
|
|
|
826 status = LUA_ERRGCMM; /* error in __gc metamethod */
|
|
|
827 }
|
|
|
828 luaD_throw(L, status); /* re-throw error */
|
|
|
829 }
|
|
|
830 }
|
|
|
831 }
|
|
|
832
|
|
|
833
|
|
|
834 /*
|
|
|
835 ** move all unreachable objects (or 'all' objects) that need
|
|
|
836 ** finalization from list 'finobj' to list 'tobefnz' (to be finalized)
|
|
|
837 */
|
|
|
838 static void separatetobefnz (lua_State *L, int all) {
|
|
|
839 global_State *g = G(L);
|
|
|
840 GCObject **p = &g->finobj;
|
|
|
841 GCObject *curr;
|
|
|
842 GCObject **lastnext = &g->tobefnz;
|
|
|
843 /* find last 'next' field in 'tobefnz' list (to add elements in its end) */
|
|
|
844 while (*lastnext != NULL)
|
|
|
845 lastnext = &gch(*lastnext)->next;
|
|
|
846 while ((curr = *p) != NULL) { /* traverse all finalizable objects */
|
|
|
847 lua_assert(!isfinalized(curr));
|
|
|
848 lua_assert(testbit(gch(curr)->marked, SEPARATED));
|
|
|
849 if (!(iswhite(curr) || all)) /* not being collected? */
|
|
|
850 p = &gch(curr)->next; /* don't bother with it */
|
|
|
851 else {
|
|
|
852 l_setbit(gch(curr)->marked, FINALIZEDBIT); /* won't be finalized again */
|
|
|
853 *p = gch(curr)->next; /* remove 'curr' from 'finobj' list */
|
|
|
854 gch(curr)->next = *lastnext; /* link at the end of 'tobefnz' list */
|
|
|
855 *lastnext = curr;
|
|
|
856 lastnext = &gch(curr)->next;
|
|
|
857 }
|
|
|
858 }
|
|
|
859 }
|
|
|
860
|
|
|
861
|
|
|
862 /*
|
|
|
863 ** if object 'o' has a finalizer, remove it from 'allgc' list (must
|
|
|
864 ** search the list to find it) and link it in 'finobj' list.
|
|
|
865 */
|
|
|
866 void luaC_checkfinalizer (lua_State *L, GCObject *o, Table *mt) {
|
|
|
867 global_State *g = G(L);
|
|
|
868 if (testbit(gch(o)->marked, SEPARATED) || /* obj. is already separated... */
|
|
|
869 isfinalized(o) || /* ... or is finalized... */
|
|
|
870 gfasttm(g, mt, TM_GC) == NULL) /* or has no finalizer? */
|
|
|
871 return; /* nothing to be done */
|
|
|
872 else { /* move 'o' to 'finobj' list */
|
|
|
873 GCObject **p;
|
|
|
874 GCheader *ho = gch(o);
|
|
|
875 if (g->sweepgc == &ho->next) { /* avoid removing current sweep object */
|
|
|
876 lua_assert(issweepphase(g));
|
|
|
877 g->sweepgc = sweeptolive(L, g->sweepgc, NULL);
|
|
|
878 }
|
|
|
879 /* search for pointer pointing to 'o' */
|
|
|
880 for (p = &g->allgc; *p != o; p = &gch(*p)->next) { /* empty */ }
|
|
|
881 *p = ho->next; /* remove 'o' from root list */
|
|
|
882 ho->next = g->finobj; /* link it in list 'finobj' */
|
|
|
883 g->finobj = o;
|
|
|
884 l_setbit(ho->marked, SEPARATED); /* mark it as such */
|
|
|
885 if (!keepinvariantout(g)) /* not keeping invariant? */
|
|
|
886 makewhite(g, o); /* "sweep" object */
|
|
|
887 else
|
|
|
888 resetoldbit(o); /* see MOVE OLD rule */
|
|
|
889 }
|
|
|
890 }
|
|
|
891
|
|
|
892 /* }====================================================== */
|
|
|
893
|
|
|
894
|
|
|
895 /*
|
|
|
896 ** {======================================================
|
|
|
897 ** GC control
|
|
|
898 ** =======================================================
|
|
|
899 */
|
|
|
900
|
|
|
901
|
|
|
902 /*
|
|
|
903 ** set a reasonable "time" to wait before starting a new GC cycle;
|
|
|
904 ** cycle will start when memory use hits threshold
|
|
|
905 */
|
|
|
906 static void setpause (global_State *g, l_mem estimate) {
|
|
|
907 l_mem debt, threshold;
|
|
|
908 estimate = estimate / PAUSEADJ; /* adjust 'estimate' */
|
|
|
909 threshold = (g->gcpause < MAX_LMEM / estimate) /* overflow? */
|
|
|
910 ? estimate * g->gcpause /* no overflow */
|
|
|
911 : MAX_LMEM; /* overflow; truncate to maximum */
|
|
|
912 debt = -cast(l_mem, threshold - gettotalbytes(g));
|
|
|
913 luaE_setdebt(g, debt);
|
|
|
914 }
|
|
|
915
|
|
|
916
|
|
|
917 #define sweepphases \
|
|
|
918 (bitmask(GCSsweepstring) | bitmask(GCSsweepudata) | bitmask(GCSsweep))
|
|
|
919
|
|
|
920
|
|
|
921 /*
|
|
|
922 ** enter first sweep phase (strings) and prepare pointers for other
|
|
|
923 ** sweep phases. The calls to 'sweeptolive' make pointers point to an
|
|
|
924 ** object inside the list (instead of to the header), so that the real
|
|
|
925 ** sweep do not need to skip objects created between "now" and the start
|
|
|
926 ** of the real sweep.
|
|
|
927 ** Returns how many objects it swept.
|
|
|
928 */
|
|
|
929 static int entersweep (lua_State *L) {
|
|
|
930 global_State *g = G(L);
|
|
|
931 int n = 0;
|
|
|
932 g->gcstate = GCSsweepstring;
|
|
|
933 lua_assert(g->sweepgc == NULL && g->sweepfin == NULL);
|
|
|
934 /* prepare to sweep strings, finalizable objects, and regular objects */
|
|
|
935 g->sweepstrgc = 0;
|
|
|
936 g->sweepfin = sweeptolive(L, &g->finobj, &n);
|
|
|
937 g->sweepgc = sweeptolive(L, &g->allgc, &n);
|
|
|
938 return n;
|
|
|
939 }
|
|
|
940
|
|
|
941
|
|
|
942 /*
|
|
|
943 ** change GC mode
|
|
|
944 */
|
|
|
945 void luaC_changemode (lua_State *L, int mode) {
|
|
|
946 global_State *g = G(L);
|
|
|
947 if (mode == g->gckind) return; /* nothing to change */
|
|
|
948 if (mode == KGC_GEN) { /* change to generational mode */
|
|
|
949 /* make sure gray lists are consistent */
|
|
|
950 luaC_runtilstate(L, bitmask(GCSpropagate));
|
|
|
951 g->GCestimate = gettotalbytes(g);
|
|
|
952 g->gckind = KGC_GEN;
|
|
|
953 }
|
|
|
954 else { /* change to incremental mode */
|
|
|
955 /* sweep all objects to turn them back to white
|
|
|
956 (as white has not changed, nothing extra will be collected) */
|
|
|
957 g->gckind = KGC_NORMAL;
|
|
|
958 entersweep(L);
|
|
|
959 luaC_runtilstate(L, ~sweepphases);
|
|
|
960 }
|
|
|
961 }
|
|
|
962
|
|
|
963
|
|
|
964 /*
|
|
|
965 ** call all pending finalizers
|
|
|
966 */
|
|
|
967 static void callallpendingfinalizers (lua_State *L, int propagateerrors) {
|
|
|
968 global_State *g = G(L);
|
|
|
969 while (g->tobefnz) {
|
|
|
970 resetoldbit(g->tobefnz);
|
|
|
971 GCTM(L, propagateerrors);
|
|
|
972 }
|
|
|
973 }
|
|
|
974
|
|
|
975
|
|
|
976 void luaC_freeallobjects (lua_State *L) {
|
|
|
977 global_State *g = G(L);
|
|
|
978 int i;
|
|
|
979 separatetobefnz(L, 1); /* separate all objects with finalizers */
|
|
|
980 lua_assert(g->finobj == NULL);
|
|
|
981 callallpendingfinalizers(L, 0);
|
|
|
982 g->currentwhite = WHITEBITS; /* this "white" makes all objects look dead */
|
|
|
983 g->gckind = KGC_NORMAL;
|
|
|
984 sweepwholelist(L, &g->finobj); /* finalizers can create objs. in 'finobj' */
|
|
|
985 sweepwholelist(L, &g->allgc);
|
|
|
986 for (i = 0; i < g->strt.size; i++) /* free all string lists */
|
|
|
987 sweepwholelist(L, &g->strt.hash[i]);
|
|
|
988 lua_assert(g->strt.nuse == 0);
|
|
|
989 }
|
|
|
990
|
|
|
991
|
|
|
992 static l_mem atomic (lua_State *L) {
|
|
|
993 global_State *g = G(L);
|
|
|
994 l_mem work = -cast(l_mem, g->GCmemtrav); /* start counting work */
|
|
|
995 GCObject *origweak, *origall;
|
|
|
996 lua_assert(!iswhite(obj2gco(g->mainthread)));
|
|
|
997 markobject(g, L); /* mark running thread */
|
|
|
998 /* registry and global metatables may be changed by API */
|
|
|
999 markvalue(g, &g->l_registry);
|
|
|
1000 markmt(g); /* mark basic metatables */
|
|
|
1001 /* remark occasional upvalues of (maybe) dead threads */
|
|
|
1002 remarkupvals(g);
|
|
|
1003 propagateall(g); /* propagate changes */
|
|
|
1004 work += g->GCmemtrav; /* stop counting (do not (re)count grays) */
|
|
|
1005 /* traverse objects caught by write barrier and by 'remarkupvals' */
|
|
|
1006 retraversegrays(g);
|
|
|
1007 work -= g->GCmemtrav; /* restart counting */
|
|
|
1008 convergeephemerons(g);
|
|
|
1009 /* at this point, all strongly accessible objects are marked. */
|
|
|
1010 /* clear values from weak tables, before checking finalizers */
|
|
|
1011 clearvalues(g, g->weak, NULL);
|
|
|
1012 clearvalues(g, g->allweak, NULL);
|
|
|
1013 origweak = g->weak; origall = g->allweak;
|
|
|
1014 work += g->GCmemtrav; /* stop counting (objects being finalized) */
|
|
|
1015 separatetobefnz(L, 0); /* separate objects to be finalized */
|
|
|
1016 markbeingfnz(g); /* mark objects that will be finalized */
|
|
|
1017 propagateall(g); /* remark, to propagate `preserveness' */
|
|
|
1018 work -= g->GCmemtrav; /* restart counting */
|
|
|
1019 convergeephemerons(g);
|
|
|
1020 /* at this point, all resurrected objects are marked. */
|
|
|
1021 /* remove dead objects from weak tables */
|
|
|
1022 clearkeys(g, g->ephemeron, NULL); /* clear keys from all ephemeron tables */
|
|
|
1023 clearkeys(g, g->allweak, NULL); /* clear keys from all allweak tables */
|
|
|
1024 /* clear values from resurrected weak tables */
|
|
|
1025 clearvalues(g, g->weak, origweak);
|
|
|
1026 clearvalues(g, g->allweak, origall);
|
|
|
1027 g->currentwhite = cast_byte(otherwhite(g)); /* flip current white */
|
|
|
1028 work += g->GCmemtrav; /* complete counting */
|
|
|
1029 return work; /* estimate of memory marked by 'atomic' */
|
|
|
1030 }
|
|
|
1031
|
|
|
1032
|
|
|
1033 static lu_mem singlestep (lua_State *L) {
|
|
|
1034 global_State *g = G(L);
|
|
|
1035 switch (g->gcstate) {
|
|
|
1036 case GCSpause: {
|
|
|
1037 /* start to count memory traversed */
|
|
|
1038 g->GCmemtrav = g->strt.size * sizeof(GCObject*);
|
|
|
1039 lua_assert(!isgenerational(g));
|
|
|
1040 restartcollection(g);
|
|
|
1041 g->gcstate = GCSpropagate;
|
|
|
1042 return g->GCmemtrav;
|
|
|
1043 }
|
|
|
1044 case GCSpropagate: {
|
|
|
1045 if (g->gray) {
|
|
|
1046 lu_mem oldtrav = g->GCmemtrav;
|
|
|
1047 propagatemark(g);
|
|
|
1048 return g->GCmemtrav - oldtrav; /* memory traversed in this step */
|
|
|
1049 }
|
|
|
1050 else { /* no more `gray' objects */
|
|
|
1051 lu_mem work;
|
|
|
1052 int sw;
|
|
|
1053 g->gcstate = GCSatomic; /* finish mark phase */
|
|
|
1054 g->GCestimate = g->GCmemtrav; /* save what was counted */;
|
|
|
1055 work = atomic(L); /* add what was traversed by 'atomic' */
|
|
|
1056 g->GCestimate += work; /* estimate of total memory traversed */
|
|
|
1057 sw = entersweep(L);
|
|
|
1058 return work + sw * GCSWEEPCOST;
|
|
|
1059 }
|
|
|
1060 }
|
|
|
1061 case GCSsweepstring: {
|
|
|
1062 int i;
|
|
|
1063 for (i = 0; i < GCSWEEPMAX && g->sweepstrgc + i < g->strt.size; i++)
|
|
|
1064 sweepwholelist(L, &g->strt.hash[g->sweepstrgc + i]);
|
|
|
1065 g->sweepstrgc += i;
|
|
|
1066 if (g->sweepstrgc >= g->strt.size) /* no more strings to sweep? */
|
|
|
1067 g->gcstate = GCSsweepudata;
|
|
|
1068 return i * GCSWEEPCOST;
|
|
|
1069 }
|
|
|
1070 case GCSsweepudata: {
|
|
|
1071 if (g->sweepfin) {
|
|
|
1072 g->sweepfin = sweeplist(L, g->sweepfin, GCSWEEPMAX);
|
|
|
1073 return GCSWEEPMAX*GCSWEEPCOST;
|
|
|
1074 }
|
|
|
1075 else {
|
|
|
1076 g->gcstate = GCSsweep;
|
|
|
1077 return 0;
|
|
|
1078 }
|
|
|
1079 }
|
|
|
1080 case GCSsweep: {
|
|
|
1081 if (g->sweepgc) {
|
|
|
1082 g->sweepgc = sweeplist(L, g->sweepgc, GCSWEEPMAX);
|
|
|
1083 return GCSWEEPMAX*GCSWEEPCOST;
|
|
|
1084 }
|
|
|
1085 else {
|
|
|
1086 /* sweep main thread */
|
|
|
1087 GCObject *mt = obj2gco(g->mainthread);
|
|
|
1088 sweeplist(L, &mt, 1);
|
|
|
1089 checkSizes(L);
|
|
|
1090 g->gcstate = GCSpause; /* finish collection */
|
|
|
1091 return GCSWEEPCOST;
|
|
|
1092 }
|
|
|
1093 }
|
|
|
1094 default: lua_assert(0); return 0;
|
|
|
1095 }
|
|
|
1096 }
|
|
|
1097
|
|
|
1098
|
|
|
1099 /*
|
|
|
1100 ** advances the garbage collector until it reaches a state allowed
|
|
|
1101 ** by 'statemask'
|
|
|
1102 */
|
|
|
1103 void luaC_runtilstate (lua_State *L, int statesmask) {
|
|
|
1104 global_State *g = G(L);
|
|
|
1105 while (!testbit(statesmask, g->gcstate))
|
|
|
1106 singlestep(L);
|
|
|
1107 }
|
|
|
1108
|
|
|
1109
|
|
|
1110 static void generationalcollection (lua_State *L) {
|
|
|
1111 global_State *g = G(L);
|
|
|
1112 lua_assert(g->gcstate == GCSpropagate);
|
|
|
1113 if (g->GCestimate == 0) { /* signal for another major collection? */
|
|
|
1114 luaC_fullgc(L, 0); /* perform a full regular collection */
|
|
|
1115 g->GCestimate = gettotalbytes(g); /* update control */
|
|
|
1116 }
|
|
|
1117 else {
|
|
|
1118 lu_mem estimate = g->GCestimate;
|
|
|
1119 luaC_runtilstate(L, bitmask(GCSpause)); /* run complete (minor) cycle */
|
|
|
1120 g->gcstate = GCSpropagate; /* skip restart */
|
|
|
1121 if (gettotalbytes(g) > (estimate / 100) * g->gcmajorinc)
|
|
|
1122 g->GCestimate = 0; /* signal for a major collection */
|
|
|
1123 else
|
|
|
1124 g->GCestimate = estimate; /* keep estimate from last major coll. */
|
|
|
1125
|
|
|
1126 }
|
|
|
1127 setpause(g, gettotalbytes(g));
|
|
|
1128 lua_assert(g->gcstate == GCSpropagate);
|
|
|
1129 }
|
|
|
1130
|
|
|
1131
|
|
|
1132 static void incstep (lua_State *L) {
|
|
|
1133 global_State *g = G(L);
|
|
|
1134 l_mem debt = g->GCdebt;
|
|
|
1135 int stepmul = g->gcstepmul;
|
|
|
1136 if (stepmul < 40) stepmul = 40; /* avoid ridiculous low values (and 0) */
|
|
|
1137 /* convert debt from Kb to 'work units' (avoid zero debt and overflows) */
|
|
|
1138 debt = (debt / STEPMULADJ) + 1;
|
|
|
1139 debt = (debt < MAX_LMEM / stepmul) ? debt * stepmul : MAX_LMEM;
|
|
|
1140 do { /* always perform at least one single step */
|
|
|
1141 lu_mem work = singlestep(L); /* do some work */
|
|
|
1142 debt -= work;
|
|
|
1143 } while (debt > -GCSTEPSIZE && g->gcstate != GCSpause);
|
|
|
1144 if (g->gcstate == GCSpause)
|
|
|
1145 setpause(g, g->GCestimate); /* pause until next cycle */
|
|
|
1146 else {
|
|
|
1147 debt = (debt / stepmul) * STEPMULADJ; /* convert 'work units' to Kb */
|
|
|
1148 luaE_setdebt(g, debt);
|
|
|
1149 }
|
|
|
1150 }
|
|
|
1151
|
|
|
1152
|
|
|
1153 /*
|
|
|
1154 ** performs a basic GC step
|
|
|
1155 */
|
|
|
1156 void luaC_forcestep (lua_State *L) {
|
|
|
1157 global_State *g = G(L);
|
|
|
1158 int i;
|
|
|
1159 if (isgenerational(g)) generationalcollection(L);
|
|
|
1160 else incstep(L);
|
|
|
1161 /* run a few finalizers (or all of them at the end of a collect cycle) */
|
|
|
1162 for (i = 0; g->tobefnz && (i < GCFINALIZENUM || g->gcstate == GCSpause); i++)
|
|
|
1163 GCTM(L, 1); /* call one finalizer */
|
|
|
1164 }
|
|
|
1165
|
|
|
1166
|
|
|
1167 /*
|
|
|
1168 ** performs a basic GC step only if collector is running
|
|
|
1169 */
|
|
|
1170 void luaC_step (lua_State *L) {
|
|
|
1171 global_State *g = G(L);
|
|
|
1172 if (g->gcrunning) luaC_forcestep(L);
|
|
|
1173 else luaE_setdebt(g, -GCSTEPSIZE); /* avoid being called too often */
|
|
|
1174 }
|
|
|
1175
|
|
|
1176
|
|
|
1177
|
|
|
1178 /*
|
|
|
1179 ** performs a full GC cycle; if "isemergency", does not call
|
|
|
1180 ** finalizers (which could change stack positions)
|
|
|
1181 */
|
|
|
1182 void luaC_fullgc (lua_State *L, int isemergency) {
|
|
|
1183 global_State *g = G(L);
|
|
|
1184 int origkind = g->gckind;
|
|
|
1185 lua_assert(origkind != KGC_EMERGENCY);
|
|
|
1186 if (isemergency) /* do not run finalizers during emergency GC */
|
|
|
1187 g->gckind = KGC_EMERGENCY;
|
|
|
1188 else {
|
|
|
1189 g->gckind = KGC_NORMAL;
|
|
|
1190 callallpendingfinalizers(L, 1);
|
|
|
1191 }
|
|
|
1192 if (keepinvariant(g)) { /* may there be some black objects? */
|
|
|
1193 /* must sweep all objects to turn them back to white
|
|
|
1194 (as white has not changed, nothing will be collected) */
|
|
|
1195 entersweep(L);
|
|
|
1196 }
|
|
|
1197 /* finish any pending sweep phase to start a new cycle */
|
|
|
1198 luaC_runtilstate(L, bitmask(GCSpause));
|
|
|
1199 luaC_runtilstate(L, ~bitmask(GCSpause)); /* start new collection */
|
|
|
1200 luaC_runtilstate(L, bitmask(GCSpause)); /* run entire collection */
|
|
|
1201 if (origkind == KGC_GEN) { /* generational mode? */
|
|
|
1202 /* generational mode must be kept in propagate phase */
|
|
|
1203 luaC_runtilstate(L, bitmask(GCSpropagate));
|
|
|
1204 }
|
|
|
1205 g->gckind = origkind;
|
|
|
1206 setpause(g, gettotalbytes(g));
|
|
|
1207 if (!isemergency) /* do not run finalizers during emergency GC */
|
|
|
1208 callallpendingfinalizers(L, 1);
|
|
|
1209 }
|
|
|
1210
|
|
|
1211 /* }====================================================== */
|
|
|
1212
|
|
|
1213
|
