34
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1
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2 /*
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3 * Copyright (C) Igor Sysoev
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4 */
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5
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6
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7 #include <ngx_config.h>
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8 #include <ngx_core.h>
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9
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10
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11 static void *ngx_radix_alloc(ngx_radix_tree_t *tree);
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12
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13
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36
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14 ngx_radix_tree_t *
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38
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15 ngx_radix_tree_create(ngx_pool_t *pool, ngx_int_t preallocate)
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34
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16 {
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36
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17 uint32_t key, mask, inc;
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34
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18 ngx_radix_tree_t *tree;
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19
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20 if (!(tree = ngx_palloc(pool, sizeof(ngx_radix_tree_t)))) {
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21 return NULL;
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22 }
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23
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24 tree->pool = pool;
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25 tree->free = NULL;
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26 tree->start = NULL;
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27 tree->size = 0;
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28
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29 if (!(tree->root = ngx_radix_alloc(tree))) {
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30 return NULL;
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31 }
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32
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33 tree->root->right = NULL;
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34 tree->root->left = NULL;
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35 tree->root->parent = NULL;
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36 tree->root->value = NGX_RADIX_NO_VALUE;
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37
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38
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38 if (preallocate == 0) {
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39 return tree;
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40 }
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41
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36
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42 /*
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43 * We preallocate the first nodes: 0, 1, 00, 01, 10, 11, 000, 001, etc.,
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44 * to increase the TLB hits even if for the first lookup iterations.
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45 * On the 32-bit platforms the 7 preallocated bits takes continuous 4K,
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38
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46 * 8 - 8K, 9 - 16K, etc. On the 64-bit platforms the 6 preallocated bits
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47 * takes continuous 4K, 7 - 8K, 8 - 16K, etc. There is no sense to
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48 * to preallocate more than one page, because further preallocation
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49 * distribute the only bit per page. Instead, the random insertion
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50 * may distribute several bits per page.
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51 *
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52 * Thus, by default we preallocate maximum
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53 * 6 bits on amd64 (64-bit platform and 4K pages)
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54 * 7 bits on i386 (32-bit platform and 4K pages)
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55 * 7 bits on sparc64 in 64-bit mode (8K pages)
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56 * 8 bits on sparc64 in 32-bit mode (8K pages)
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36
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57 */
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58
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38
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59 if (preallocate == -1) {
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60 switch (ngx_pagesize / sizeof(ngx_radix_tree_t)) {
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61
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62 /* amd64 */
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63 case 128:
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64 preallocate = 6;
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65 break;
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66
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67 /* i386, sparc64 */
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68 case 256:
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69 preallocate = 7;
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70 break;
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71
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72 /* sparc64 in 32-bit mode */
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73 default:
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74 preallocate = 8;
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75 }
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76 }
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77
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36
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78 mask = 0;
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79 inc = 0x80000000;
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80
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81 while (preallocate--) {
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82
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83 key = 0;
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84 mask >>= 1;
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85 mask |= 0x80000000;
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86
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87 do {
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88 if (ngx_radix32tree_insert(tree, key, mask, NGX_RADIX_NO_VALUE)
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89 != NGX_OK)
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90 {
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91 return NULL;
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92 }
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93
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94 key += inc;
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95
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96 } while (key);
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97
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98 inc >>= 1;
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99 }
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100
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101 return tree;
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102 }
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103
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104
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36
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105 ngx_int_t
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106 ngx_radix32tree_insert(ngx_radix_tree_t *tree, uint32_t key, uint32_t mask,
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107 uintptr_t value)
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34
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108 {
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109 uint32_t bit;
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110 ngx_radix_node_t *node, *next;
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111
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112 bit = 0x80000000;
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113
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114 node = tree->root;
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115 next = tree->root;
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116
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117 while (bit & mask) {
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118 if (key & bit) {
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119 next = node->right;
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120
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121 } else {
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122 next = node->left;
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123 }
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124
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125 if (next == NULL) {
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126 break;
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127 }
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128
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129 bit >>= 1;
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130 node = next;
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131 }
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132
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133 if (next) {
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134 if (node->value != NGX_RADIX_NO_VALUE) {
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135 return NGX_BUSY;
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136 }
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137
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138 node->value = value;
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139 return NGX_OK;
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140 }
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141
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142 while (bit & mask) {
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143 if (!(next = ngx_radix_alloc(tree))) {
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144 return NGX_ERROR;
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145 }
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146
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147 next->right = NULL;
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148 next->left = NULL;
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149 next->parent = node;
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150 next->value = NGX_RADIX_NO_VALUE;
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151
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152 if (key & bit) {
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153 node->right = next;
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154
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155 } else {
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156 node->left = next;
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157 }
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158
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159 bit >>= 1;
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160 node = next;
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161 }
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162
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163 node->value = value;
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164
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165 return NGX_OK;
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166 }
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167
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168
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36
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169 ngx_int_t
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170 ngx_radix32tree_delete(ngx_radix_tree_t *tree, uint32_t key, uint32_t mask)
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34
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171 {
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172 uint32_t bit;
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173 ngx_radix_node_t *node;
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174
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175 bit = 0x80000000;
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176 node = tree->root;
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177
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178 while (node && (bit & mask)) {
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179 if (key & bit) {
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180 node = node->right;
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181
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182 } else {
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183 node = node->left;
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184 }
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185
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186 bit >>= 1;
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187 }
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188
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189 if (node == NULL) {
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190 return NGX_ERROR;
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191 }
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192
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193 if (node->right || node->left) {
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194 if (node->value != NGX_RADIX_NO_VALUE) {
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195 node->value = NGX_RADIX_NO_VALUE;
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196 return NGX_OK;
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197 }
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198
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199 return NGX_ERROR;
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200 }
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201
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202 for ( ;; ) {
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203 if (node->parent->right == node) {
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204 node->parent->right = NULL;
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205 } else {
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206 node->parent->left = NULL;
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207 }
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208
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209 node->right = tree->free;
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210 tree->free = node;
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211
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212 node = node->parent;
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213
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214 if (node->right
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215 || node->left
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216 || node->value != NGX_RADIX_NO_VALUE
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217 || node->parent == NULL)
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218 {
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219 break;
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220 }
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221 }
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222
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223 return NGX_OK;
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224 }
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225
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226
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36
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227 uintptr_t
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228 ngx_radix32tree_find(ngx_radix_tree_t *tree, uint32_t key)
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34
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229 {
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230 uint32_t bit;
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231 uintptr_t value;
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232 ngx_radix_node_t *node;
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233
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234 bit = 0x80000000;
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235 value = NGX_RADIX_NO_VALUE;
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236 node = tree->root;
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237
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238 while (node) {
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239 if (node->value != NGX_RADIX_NO_VALUE) {
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240 value = node->value;
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241 }
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242
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243 if (key & bit) {
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244 node = node->right;
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245
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246 } else {
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247 node = node->left;
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248 }
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249
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250 bit >>= 1;
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251 }
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252
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253 return value;
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254 }
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255
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256
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36
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257 static void *
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258 ngx_radix_alloc(ngx_radix_tree_t *tree)
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34
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259 {
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260 char *p;
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261
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262 if (tree->free) {
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263 p = (char *) tree->free;
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264 tree->free = tree->free->right;
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265 return p;
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266 }
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267
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268 if (tree->size < sizeof(ngx_radix_node_t)) {
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269 if (!(tree->start = ngx_palloc(tree->pool, ngx_pagesize))) {
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270 return NULL;
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271 }
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272
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273 tree->size = ngx_pagesize;
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274 }
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275
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276 p = tree->start;
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277 tree->start += sizeof(ngx_radix_node_t);
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278 tree->size -= sizeof(ngx_radix_node_t);
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279
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280 return p;
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281 }
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