1 | /*
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2 | ** pool.c - memory pool
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3 | **
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4 | ** See Copyright Notice in mruby.h
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5 | */
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6 |
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7 | #include <stddef.h>
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8 | #include <stdint.h>
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9 | #include <string.h>
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10 | #include "mruby.h"
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11 |
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12 | /* configuration section */
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13 | /* allocated memory address should be multiple of POOL_ALIGNMENT */
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14 | /* or undef it if alignment does not matter */
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15 | #ifndef POOL_ALIGNMENT
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16 | #define POOL_ALIGNMENT 4
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17 | #endif
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18 | /* page size of memory pool */
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19 | #ifndef POOL_PAGE_SIZE
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20 | #define POOL_PAGE_SIZE 16000
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21 | #endif
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22 | /* end of configuration section */
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23 |
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24 | struct mrb_pool_page {
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25 | struct mrb_pool_page *next;
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26 | size_t offset;
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27 | size_t len;
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28 | void *last;
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29 | char page[];
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30 | };
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31 |
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32 | struct mrb_pool {
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33 | mrb_state *mrb;
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34 | struct mrb_pool_page *pages;
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35 | };
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36 |
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37 | #undef TEST_POOL
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38 | #ifdef TEST_POOL
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39 |
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40 | #define mrb_malloc_simple(m,s) malloc(s)
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41 | #define mrb_free(m,p) free(p)
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42 | #endif
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43 |
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44 | #ifdef POOL_ALIGNMENT
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45 | # define ALIGN_PADDING(x) ((SIZE_MAX - (x) + 1) & (POOL_ALIGNMENT - 1))
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46 | #else
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47 | # define ALIGN_PADDING(x) (0)
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48 | #endif
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49 |
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50 | MRB_API mrb_pool*
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51 | mrb_pool_open(mrb_state *mrb)
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52 | {
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53 | mrb_pool *pool = (mrb_pool *)mrb_malloc_simple(mrb, sizeof(mrb_pool));
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54 |
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55 | if (pool) {
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56 | pool->mrb = mrb;
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57 | pool->pages = NULL;
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58 | }
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59 |
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60 | return pool;
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61 | }
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62 |
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63 | MRB_API void
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64 | mrb_pool_close(mrb_pool *pool)
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65 | {
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66 | struct mrb_pool_page *page, *tmp;
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67 |
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68 | if (!pool) return;
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69 | page = pool->pages;
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70 | while (page) {
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71 | tmp = page;
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72 | page = page->next;
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73 | mrb_free(pool->mrb, tmp);
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74 | }
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75 | mrb_free(pool->mrb, pool);
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76 | }
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77 |
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78 | static struct mrb_pool_page*
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79 | page_alloc(mrb_pool *pool, size_t len)
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80 | {
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81 | struct mrb_pool_page *page;
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82 |
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83 | if (len < POOL_PAGE_SIZE)
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84 | len = POOL_PAGE_SIZE;
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85 | page = (struct mrb_pool_page *)mrb_malloc_simple(pool->mrb, sizeof(struct mrb_pool_page)+len);
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86 | if (page) {
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87 | page->offset = 0;
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88 | page->len = len;
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89 | }
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90 |
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91 | return page;
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92 | }
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93 |
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94 | MRB_API void*
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95 | mrb_pool_alloc(mrb_pool *pool, size_t len)
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96 | {
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97 | struct mrb_pool_page *page;
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98 | size_t n;
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99 |
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100 | if (!pool) return NULL;
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101 | len += ALIGN_PADDING(len);
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102 | page = pool->pages;
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103 | while (page) {
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104 | if (page->offset + len <= page->len) {
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105 | n = page->offset;
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106 | page->offset += len;
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107 | page->last = (char*)page->page+n;
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108 | return page->last;
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109 | }
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110 | page = page->next;
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111 | }
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112 | page = page_alloc(pool, len);
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113 | if (!page) return NULL;
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114 | page->offset = len;
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115 | page->next = pool->pages;
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116 | pool->pages = page;
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117 |
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118 | page->last = (void*)page->page;
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119 | return page->last;
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120 | }
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121 |
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122 | MRB_API mrb_bool
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123 | mrb_pool_can_realloc(mrb_pool *pool, void *p, size_t len)
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124 | {
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125 | struct mrb_pool_page *page;
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126 |
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127 | if (!pool) return FALSE;
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128 | len += ALIGN_PADDING(len);
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129 | page = pool->pages;
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130 | while (page) {
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131 | if (page->last == p) {
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132 | size_t beg;
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133 |
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134 | beg = (char*)p - page->page;
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135 | if (beg + len > page->len) return FALSE;
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136 | return TRUE;
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137 | }
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138 | page = page->next;
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139 | }
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140 | return FALSE;
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141 | }
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142 |
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143 | MRB_API void*
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144 | mrb_pool_realloc(mrb_pool *pool, void *p, size_t oldlen, size_t newlen)
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145 | {
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146 | struct mrb_pool_page *page;
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147 | void *np;
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148 |
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149 | if (!pool) return NULL;
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150 | oldlen += ALIGN_PADDING(oldlen);
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151 | newlen += ALIGN_PADDING(newlen);
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152 | page = pool->pages;
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153 | while (page) {
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154 | if (page->last == p) {
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155 | size_t beg;
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156 |
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157 | beg = (char*)p - page->page;
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158 | if (beg + oldlen != page->offset) break;
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159 | if (beg + newlen > page->len) {
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160 | page->offset = beg;
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161 | break;
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162 | }
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163 | page->offset = beg + newlen;
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164 | return p;
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165 | }
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166 | page = page->next;
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167 | }
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168 | np = mrb_pool_alloc(pool, newlen);
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169 | if (np == NULL) {
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170 | return NULL;
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171 | }
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172 | memcpy(np, p, oldlen);
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173 | return np;
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174 | }
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175 |
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176 | #ifdef TEST_POOL
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177 | int
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178 | main(void)
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179 | {
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180 | int i, len = 250;
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181 | mrb_pool *pool;
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182 | void *p;
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183 |
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184 | pool = mrb_pool_open(NULL);
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185 | p = mrb_pool_alloc(pool, len);
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186 | for (i=1; i<20; i++) {
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187 | printf("%p (len=%d) %ud\n", p, len, mrb_pool_can_realloc(pool, p, len*2));
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188 | p = mrb_pool_realloc(pool, p, len, len*2);
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189 | len *= 2;
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190 | }
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191 | mrb_pool_close(pool);
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192 | return 0;
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193 | }
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194 | #endif
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