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258
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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 #include <ngx_config.h>
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7 #include <ngx_core.h>
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8
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9 /*
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10
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11 12
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12 2048 2 11
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13 1024 4 10
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14 512 8 9
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15 256 16 8
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16
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17 128 32 4 32 7
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18
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19 64 64 8 63 6 1
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20 32 128 16 127 5 1
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21 16 256 32 254 4 2
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22 8 512 64 504 3 8
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23
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24 */
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25
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26
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27 #define NGX_SLAB_PAGE_MASK 3
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28 #define NGX_SLAB_PAGE 0
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29 #define NGX_SLAB_BIG 1
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30 #define NGX_SLAB_EXACT 2
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31 #define NGX_SLAB_SMALL 3
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32
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33 #if (NGX_PTR_SIZE == 4)
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34
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35 #define NGX_SLAB_PAGE_FREE 0
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36 #define NGX_SLAB_PAGE_BUSY 0xffffffff
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37 #define NGX_SLAB_PAGE_START 0x80000000
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38
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39 #define NGX_SLAB_SHIFT_MASK 0x0000000f
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40 #define NGX_SLAB_MAP_MASK 0xffff0000
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41 #define NGX_SLAB_MAP_SHIFT 16
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42
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43 #define NGX_SLAB_BUSY 0xffffffff
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44
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45 #else /* (NGX_PTR_SIZE == 8) */
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46
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47 #define NGX_SLAB_PAGE_FREE 0
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48 #define NGX_SLAB_PAGE_BUSY 0xffffffffffffffff
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49 #define NGX_SLAB_PAGE_START 0x8000000000000000
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50
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51 #define NGX_SLAB_SHIFT_MASK 0x000000000000000f
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52 #define NGX_SLAB_MAP_MASK 0xffffffff00000000
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53 #define NGX_SLAB_MAP_SHIFT 32
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54
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55 #define NGX_SLAB_BUSY 0xffffffffffffffff
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56
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57 #endif
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58
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59
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60 #if (NGX_DEBUG_MALLOC)
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61 #define ngx_slab_junk(p, size) ngx_memset(p, 0xD0, size)
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62 #else
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63 #define ngx_slab_junk(p, size)
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64 #endif
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65
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66 static ngx_slab_page_t *ngx_slab_alloc_pages(ngx_slab_pool_t *pool,
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67 ngx_uint_t pages);
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68 static void ngx_slab_free_pages(ngx_slab_pool_t *pool, ngx_slab_page_t *page,
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69 ngx_uint_t pages);
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70
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71
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72 static ngx_uint_t ngx_slab_max_size;
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73 static ngx_uint_t ngx_slab_exact_size;
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74 static ngx_uint_t ngx_slab_exact_shift;
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75
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76
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77 void
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78 ngx_slab_init(ngx_slab_pool_t *pool)
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79 {
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80 u_char *p;
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81 size_t size;
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82 ngx_int_t m;
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83 ngx_uint_t i, n, pages;
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84 ngx_slab_page_t *slots;
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85
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86 /* STUB */
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87 if (ngx_slab_max_size == 0) {
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88 ngx_slab_max_size = ngx_pagesize / 2;
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89 ngx_slab_exact_size = ngx_pagesize / (8 * sizeof(uintptr_t));
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90 for (n = ngx_slab_exact_size; n >>= 1; ngx_slab_exact_shift++) {
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91 /* void */
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92 }
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93 }
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94 /**/
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95
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96 pool->min_size = 1 << pool->min_shift;
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97
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98 p = (u_char *) pool + sizeof(ngx_slab_pool_t);
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99 size = pool->end - p;
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100
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101 ngx_slab_junk(p, size);
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102
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103 slots = (ngx_slab_page_t *) p;
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104 n = ngx_pagesize_shift - pool->min_shift;
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105
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106 for (i = 0; i < n; i++) {
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107 slots[i].slab = 0;
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108 slots[i].next = &slots[i];
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109 slots[i].prev = 0;
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110 }
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111
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112 p += n * sizeof(ngx_slab_page_t);
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113
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114 /* STUB: possible overflow on 64-bit platform */
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115 pages = (ngx_uint_t) ((uint64_t) size * ngx_pagesize
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116 / (ngx_pagesize + sizeof(ngx_slab_page_t))
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117 / ngx_pagesize);
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118
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119 ngx_memzero(p, pages * sizeof(ngx_slab_page_t));
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120
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121 pool->pages = (ngx_slab_page_t *) p;
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122
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123 pool->free.prev = 0;
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124 pool->free.next = (ngx_slab_page_t *) p;
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125
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126 pool->pages->slab = pages;
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127 pool->pages->next = &pool->free;
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128 pool->pages->prev = (uintptr_t) &pool->free;
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129
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130 pool->start = (u_char *)
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131 ngx_align((uintptr_t) p + pages * sizeof(ngx_slab_page_t),
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132 ngx_pagesize);
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133
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134 m = pages - (pool->end - pool->start) / ngx_pagesize;
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135 if (m > 0) {
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136 pages -= m;
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137 pool->pages->slab = pages;
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138 }
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139
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140 #if 0
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141 ngx_log_error(NGX_LOG_ALERT, ngx_cycle->log, 0, "slab: %p, %p, %ui, %d",
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142 pool, pool->start, pages,
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143 (pool->end - pool->start) / ngx_pagesize - pages);
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144 #endif
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145 }
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146
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147
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148 void *
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149 ngx_slab_alloc(ngx_slab_pool_t *pool, size_t size)
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150 {
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272
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151 void *p;
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152
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153 ngx_shmtx_lock(&pool->mutex);
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154
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155 p = ngx_slab_alloc_locked(pool, size);
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156
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157 ngx_shmtx_unlock(&pool->mutex);
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158
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159 return p;
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160 }
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161
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162
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163 void *
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164 ngx_slab_alloc_locked(ngx_slab_pool_t *pool, size_t size)
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165 {
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258
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166 size_t s;
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260
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167 uintptr_t p, n, m, mask, *bitmap;
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168 ngx_uint_t i, slot, shift, map;
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258
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169 ngx_slab_page_t *page, *prev, *slots;
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170
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272
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171 if (size >= ngx_slab_max_size) {
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258
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172
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272
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173 ngx_log_debug1(NGX_LOG_DEBUG_ALLOC, ngx_cycle->log, 0,
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174 "slab alloc: %uz", size);
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175
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258
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176 page = ngx_slab_alloc_pages(pool, (size + ngx_pagesize - 1)
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177 >> ngx_pagesize_shift);
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178 if (page) {
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179 p = (page - pool->pages) << ngx_pagesize_shift;
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180 p += (uintptr_t) pool->start;
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181
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182 } else {
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183 p = 0;
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184 }
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185
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186 goto done;
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187 }
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188
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189 if (size > pool->min_size) {
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190 shift = 1;
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191 for (s = size - 1; s >>= 1; shift++) { /* void */ }
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192 slot = shift - pool->min_shift;
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193
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194 } else {
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195 size = pool->min_size;
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196 shift = pool->min_shift;
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197 slot = 0;
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198 }
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199
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200 ngx_log_debug2(NGX_LOG_DEBUG_ALLOC, ngx_cycle->log, 0,
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201 "slab alloc: %uz slot: %ui", size, slot);
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202
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203 slots = (ngx_slab_page_t *) ((u_char *) pool + sizeof(ngx_slab_pool_t));
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204 page = slots[slot].next;
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205
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206 if (page->next != page) {
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207
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272
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208 if (shift < ngx_slab_exact_shift) {
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258
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209
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210 do {
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211 p = (page - pool->pages) << ngx_pagesize_shift;
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212 bitmap = (uintptr_t *) (pool->start + p);
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213
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214 map = (1 << (ngx_pagesize_shift - shift))
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215 / (sizeof(uintptr_t) * 8);
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216
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217 for (n = 0; n < map; n++) {
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218
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219 if (bitmap[n] != NGX_SLAB_BUSY) {
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220
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221 for (m = 1, i = 0; m; m <<= 1, i++) {
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222 if ((bitmap[n] & m)) {
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223 continue;
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224 }
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225
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226 bitmap[n] |= m;
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272
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227
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228 i = ((n * sizeof(uintptr_t) * 8) << shift)
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229 + (i << shift);
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258
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230
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231 if (bitmap[n] == NGX_SLAB_BUSY) {
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232 for (n = n + 1; n < map; n++) {
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233 if (bitmap[n] != NGX_SLAB_BUSY) {
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234 p = (uintptr_t) bitmap + i;
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235
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236 goto done;
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237 }
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238 }
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239
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240 prev = (ngx_slab_page_t *)
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241 (page->prev & ~NGX_SLAB_PAGE_MASK);
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242 prev->next = page->next;
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243 page->next->prev = page->prev;
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244
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245 page->next = NULL;
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246 page->prev = NGX_SLAB_SMALL;
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247 }
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248
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249 p = (uintptr_t) bitmap + i;
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250
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251 goto done;
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252 }
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253 }
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254 }
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255
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256 page = page->next;
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257
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258 } while (page);
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259
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272
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260 } else if (shift == ngx_slab_exact_shift) {
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258
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261
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262 do {
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263 if (page->slab != NGX_SLAB_BUSY) {
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264
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265 for (m = 1, i = 0; m; m <<= 1, i++) {
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266 if ((page->slab & m)) {
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267 continue;
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268 }
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269
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270 page->slab |= m;
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271
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272 if (page->slab == NGX_SLAB_BUSY) {
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273 prev = (ngx_slab_page_t *)
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274 (page->prev & ~NGX_SLAB_PAGE_MASK);
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275 prev->next = page->next;
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276 page->next->prev = page->prev;
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277
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278 page->next = NULL;
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279 page->prev = NGX_SLAB_EXACT;
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280 }
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281
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282 p = (page - pool->pages) << ngx_pagesize_shift;
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283 p += i << shift;
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284 p += (uintptr_t) pool->start;
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285
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286 goto done;
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287 }
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288 }
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289
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290 page = page->next;
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291
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292 } while (page);
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293
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272
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294 } else { /* shift > ngx_slab_exact_shift */
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258
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295
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296 n = ngx_pagesize_shift - (page->slab & NGX_SLAB_SHIFT_MASK);
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297 n = 1 << n;
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298 n = (1 << n) - 1;
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299 mask = n << NGX_SLAB_MAP_SHIFT;
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300
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301 do {
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302 if ((page->slab & NGX_SLAB_MAP_MASK) != mask) {
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303
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260
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304 for (m = (uintptr_t) 1 << NGX_SLAB_MAP_SHIFT, i = 0;
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258
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305 m & mask;
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306 m <<= 1, i++)
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307 {
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308 if ((page->slab & m)) {
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309 continue;
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310 }
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311
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312 page->slab |= m;
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313
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314 if ((page->slab & NGX_SLAB_MAP_MASK) == mask) {
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315 prev = (ngx_slab_page_t *)
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316 (page->prev & ~NGX_SLAB_PAGE_MASK);
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317 prev->next = page->next;
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318 page->next->prev = page->prev;
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319
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320 page->next = NULL;
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321 page->prev = NGX_SLAB_BIG;
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322 }
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323
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324 p = (page - pool->pages) << ngx_pagesize_shift;
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325 p += i << shift;
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326 p += (uintptr_t) pool->start;
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327
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328 goto done;
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329 }
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330 }
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331
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332 page = page->next;
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333
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334 } while (page);
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335 }
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336 }
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337
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338 page = ngx_slab_alloc_pages(pool, 1);
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339
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340 if (page) {
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272
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341 if (shift < ngx_slab_exact_shift) {
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258
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342 p = (page - pool->pages) << ngx_pagesize_shift;
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343 bitmap = (uintptr_t *) (pool->start + p);
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344
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345 s = 1 << shift;
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346 n = (1 << (ngx_pagesize_shift - shift)) / 8 / s;
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347
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348 if (n == 0) {
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349 n = 1;
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350 }
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351
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352 bitmap[0] = (2 << n) - 1;
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353
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354 map = (1 << (ngx_pagesize_shift - shift)) / (sizeof(uintptr_t) * 8);
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355
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356 for (i = 1; i < map; i++) {
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357 bitmap[i] = 0;
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358 }
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359
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360 page->slab = shift;
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361 page->next = &slots[slot];
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362 page->prev = (uintptr_t) &slots[slot] | NGX_SLAB_SMALL;
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363
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364 slots[slot].next = page;
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365
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366 p = ((page - pool->pages) << ngx_pagesize_shift) + s * n;
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367 p += (uintptr_t) pool->start;
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368
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369 goto done;
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370
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272
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371 } else if (shift == ngx_slab_exact_shift) {
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258
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372
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373 page->slab = 1;
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374 page->next = &slots[slot];
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375 page->prev = (uintptr_t) &slots[slot] | NGX_SLAB_EXACT;
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376
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377 slots[slot].next = page;
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378
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379 p = (page - pool->pages) << ngx_pagesize_shift;
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380 p += (uintptr_t) pool->start;
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381
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382 goto done;
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383
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272
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384 } else { /* shift > ngx_slab_exact_shift */
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258
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385
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260
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386 page->slab = ((uintptr_t) 1 << NGX_SLAB_MAP_SHIFT) | shift;
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258
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387 page->next = &slots[slot];
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388 page->prev = (uintptr_t) &slots[slot] | NGX_SLAB_BIG;
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389
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390 slots[slot].next = page;
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391
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392 p = (page - pool->pages) << ngx_pagesize_shift;
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393 p += (uintptr_t) pool->start;
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394
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395 goto done;
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396 }
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397 }
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398
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399 p = 0;
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400
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401 done:
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402
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403 ngx_log_debug1(NGX_LOG_DEBUG_ALLOC, ngx_cycle->log, 0, "slab alloc: %p", p);
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404
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405 return (void *) p;
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406 }
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407
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408
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409 void
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410 ngx_slab_free(ngx_slab_pool_t *pool, void *p)
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411 {
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272
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412 ngx_shmtx_lock(&pool->mutex);
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413
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414 ngx_slab_free_locked(pool, p);
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415
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416 ngx_shmtx_unlock(&pool->mutex);
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417 }
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418
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419
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420 void
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421 ngx_slab_free_locked(ngx_slab_pool_t *pool, void *p)
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422 {
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258
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423 size_t size;
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424 uintptr_t slab, *bitmap;
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425 ngx_uint_t n, m, type, slot, shift, map;
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426 ngx_slab_page_t *slots, *page;
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427
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428 ngx_log_debug1(NGX_LOG_DEBUG_ALLOC, ngx_cycle->log, 0, "slab free: %p", p);
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429
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430 if ((u_char *) p < pool->start || (u_char *) p > pool->end) {
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431 ngx_log_error(NGX_LOG_ALERT, ngx_cycle->log, 0,
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432 "ngx_slab_free(): outside of pool");
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433 goto fail;
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434 }
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435
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436 n = ((u_char *) p - pool->start) >> ngx_pagesize_shift;
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437 page = &pool->pages[n];
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438 slab = page->slab;
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439 type = page->prev & NGX_SLAB_PAGE_MASK;
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440
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441 switch (type) {
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442
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443 case NGX_SLAB_SMALL:
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444
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445 shift = slab & NGX_SLAB_SHIFT_MASK;
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446 size = 1 << shift;
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447
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448 if ((uintptr_t) p & (size - 1)) {
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449 goto wrong_chunk;
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450 }
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451
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452 n = ((uintptr_t) p & (ngx_pagesize - 1)) >> shift;
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453 m = 1 << (n & (sizeof(uintptr_t) * 8 - 1));
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454 n /= (sizeof(uintptr_t) * 8);
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455 bitmap = (uintptr_t *) ((uintptr_t) p & ~(ngx_pagesize - 1));
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456
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457 if (bitmap[n] & m) {
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458
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459 if (page->next == NULL) {
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460 slots = (ngx_slab_page_t *)
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461 ((u_char *) pool + sizeof(ngx_slab_pool_t));
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462 slot = shift - pool->min_shift;
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463
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464 page->next = slots[slot].next;
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465 slots[slot].next = page;
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466
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467 page->prev = (uintptr_t) &slots[slot] | NGX_SLAB_SMALL;
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468 page->next->prev = (uintptr_t) page | NGX_SLAB_SMALL;
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469 }
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470
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471 bitmap[n] &= ~m;
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472
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473 n = (1 << (ngx_pagesize_shift - shift)) / 8 / (1 << shift);
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474
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475 if (n == 0) {
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476 n = 1;
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477 }
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478
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479 if (bitmap[0] & ~((1 << n) - 1)) {
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480 goto done;
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481 }
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482
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483 map = (1 << (ngx_pagesize_shift - shift)) / (sizeof(uintptr_t) * 8);
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484
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485 for (n = 1; n < map; n++) {
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486 if (bitmap[n]) {
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487 goto done;
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488 }
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489 }
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490
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491 ngx_slab_free_pages(pool, page, 1);
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492
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493 goto done;
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494 }
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495
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496 goto chunk_already_free;
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497
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498 case NGX_SLAB_EXACT:
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499
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500 m = 1 << (((uintptr_t) p & (ngx_pagesize - 1)) >> ngx_slab_exact_shift);
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501 size = ngx_slab_exact_size;
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502
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503 if ((uintptr_t) p & (size - 1)) {
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504 goto wrong_chunk;
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505 }
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506
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507 if (slab & m) {
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508 if (slab == NGX_SLAB_BUSY) {
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509 slots = (ngx_slab_page_t *)
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510 ((u_char *) pool + sizeof(ngx_slab_pool_t));
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511 slot = ngx_slab_exact_shift - pool->min_shift;
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512
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513 page->next = slots[slot].next;
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514 slots[slot].next = page;
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515
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516 page->prev = (uintptr_t) &slots[slot] | NGX_SLAB_EXACT;
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517 page->next->prev = (uintptr_t) page | NGX_SLAB_EXACT;
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518 }
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519
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520 page->slab &= ~m;
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521
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522 if (page->slab) {
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523 goto done;
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524 }
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525
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526 ngx_slab_free_pages(pool, page, 1);
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527
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528 goto done;
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529 }
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530
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531 goto chunk_already_free;
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532
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533 case NGX_SLAB_BIG:
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534
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535 shift = slab & NGX_SLAB_SHIFT_MASK;
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536 size = 1 << shift;
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537
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538 if ((uintptr_t) p & (size - 1)) {
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539 goto wrong_chunk;
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540 }
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541
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542 m = 1 << ((((uintptr_t) p & (ngx_pagesize - 1)) >> shift)
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543 + NGX_SLAB_MAP_SHIFT);
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544
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545 if (slab & m) {
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546
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547 if (page->next == NULL) {
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548 slots = (ngx_slab_page_t *)
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549 ((u_char *) pool + sizeof(ngx_slab_pool_t));
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550 slot = shift - pool->min_shift;
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551
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552 page->next = slots[slot].next;
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553 slots[slot].next = page;
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554
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555 page->prev = (uintptr_t) &slots[slot] | NGX_SLAB_BIG;
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556 page->next->prev = (uintptr_t) page | NGX_SLAB_BIG;
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557 }
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558
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559 page->slab &= ~m;
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560
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561 if (page->slab & NGX_SLAB_MAP_MASK) {
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562 goto done;
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563 }
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564
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565 ngx_slab_free_pages(pool, page, 1);
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566
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567 goto done;
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568 }
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569
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570 goto chunk_already_free;
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571
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572 case NGX_SLAB_PAGE:
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573
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574 if ((uintptr_t) p & (ngx_pagesize - 1)) {
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575 goto wrong_chunk;
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576 }
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577
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578 if (slab == NGX_SLAB_PAGE_FREE) {
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579 ngx_log_error(NGX_LOG_ALERT, ngx_cycle->log, 0,
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580 "ngx_slab_free(): page is already free");
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581 goto fail;
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582 }
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583
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584 if (slab == NGX_SLAB_PAGE_BUSY) {
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585 ngx_log_error(NGX_LOG_ALERT, ngx_cycle->log, 0,
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586 "ngx_slab_free(): pointer to wrong page");
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587 goto fail;
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588 }
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589
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590 n = ((u_char *) p - pool->start) >> ngx_pagesize_shift;
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591 size = slab & ~NGX_SLAB_PAGE_START;
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592
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593 ngx_slab_free_pages(pool, &pool->pages[n], size);
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594
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595 size <<= ngx_pagesize_shift;
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596
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597 goto done;
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598 }
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599
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600 /* not reached */
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601
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602 return;
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603
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604 done:
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605
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606 ngx_slab_junk(p, size);
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607
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608 return;
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609
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610 wrong_chunk:
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611
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612 ngx_log_error(NGX_LOG_ALERT, ngx_cycle->log, 0,
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613 "ngx_slab_free(): pointer to wrong chunk");
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614
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615 goto fail;
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616
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617 chunk_already_free:
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618
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619 ngx_log_error(NGX_LOG_ALERT, ngx_cycle->log, 0,
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620 "ngx_slab_free(): chunk is already free");
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621
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622 fail:
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623
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624 return;
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625 }
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626
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627
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628 static ngx_slab_page_t *
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629 ngx_slab_alloc_pages(ngx_slab_pool_t *pool, ngx_uint_t pages)
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630 {
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631 ngx_slab_page_t *page, *p;
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632
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633 for (page = pool->free.next; page != &pool->free; page = page->next) {
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634
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635 if (page->slab >= pages) {
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636
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637 if (page->slab > pages) {
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638 page[pages].slab = page->slab - pages;
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639 page[pages].next = page->next;
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640 page[pages].prev = page->prev;
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641
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642 p = (ngx_slab_page_t *) page->prev;
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643 p->next = &page[pages];
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644 page->next->prev = (uintptr_t) &page[pages];
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645
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646 } else {
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647 p = (ngx_slab_page_t *) page->prev;
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648 p->next = page->next;
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649 page->next->prev = page->prev;
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650 }
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651
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652 page->slab = pages | NGX_SLAB_PAGE_START;
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653
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654 #if (NGX_DEBUG)
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655 page->next = NULL;
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656 page->prev = NGX_SLAB_PAGE;
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657 #endif
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658
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659 if (--pages == 0) {
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660 return page;
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661 }
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662
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663 for (p = page + 1; pages; pages--) {
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664 p->slab = NGX_SLAB_PAGE_BUSY;
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665 #if (NGX_DEBUG)
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666 p->next = NULL;
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667 p->prev = NGX_SLAB_PAGE;
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668 #endif
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669 p++;
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670 }
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671
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672 return page;
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673 }
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674 }
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675
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676 ngx_log_error(NGX_LOG_ALERT, ngx_cycle->log, NGX_ENOMEM,
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677 "ngx_slab_alloc(): failed");
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272
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678
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258
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679 return NULL;
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680 }
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681
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682
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683 static void
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684 ngx_slab_free_pages(ngx_slab_pool_t *pool, ngx_slab_page_t *page,
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685 ngx_uint_t pages)
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686 {
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687 ngx_slab_page_t *prev;
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688
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689 page->slab = pages--;
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690
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691 if (pages) {
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692 ngx_memzero(&page[1], pages * sizeof(ngx_slab_page_t));
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693 }
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694
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272
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695 if (page->next) {
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696 prev = (ngx_slab_page_t *) (page->prev & ~NGX_SLAB_PAGE_MASK);
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697 prev->next = page->next;
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698 page->next->prev = page->prev;
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699 }
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258
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700
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272
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701 page->prev = (uintptr_t) &pool->free;
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258
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702 page->next = pool->free.next;
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272
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703
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704 page->next->prev = (uintptr_t) page;
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705
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258
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706 pool->free.next = page;
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707 }
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