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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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660
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4 * Copyright (C) Nginx, Inc.
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258
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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 #define NGX_SLAB_PAGE_MASK 3
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12 #define NGX_SLAB_PAGE 0
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13 #define NGX_SLAB_BIG 1
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14 #define NGX_SLAB_EXACT 2
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15 #define NGX_SLAB_SMALL 3
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16
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17 #if (NGX_PTR_SIZE == 4)
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18
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19 #define NGX_SLAB_PAGE_FREE 0
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20 #define NGX_SLAB_PAGE_BUSY 0xffffffff
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21 #define NGX_SLAB_PAGE_START 0x80000000
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22
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23 #define NGX_SLAB_SHIFT_MASK 0x0000000f
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24 #define NGX_SLAB_MAP_MASK 0xffff0000
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25 #define NGX_SLAB_MAP_SHIFT 16
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26
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27 #define NGX_SLAB_BUSY 0xffffffff
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28
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29 #else /* (NGX_PTR_SIZE == 8) */
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30
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31 #define NGX_SLAB_PAGE_FREE 0
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32 #define NGX_SLAB_PAGE_BUSY 0xffffffffffffffff
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33 #define NGX_SLAB_PAGE_START 0x8000000000000000
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34
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35 #define NGX_SLAB_SHIFT_MASK 0x000000000000000f
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36 #define NGX_SLAB_MAP_MASK 0xffffffff00000000
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37 #define NGX_SLAB_MAP_SHIFT 32
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38
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39 #define NGX_SLAB_BUSY 0xffffffffffffffff
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40
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41 #endif
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42
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43
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44 #if (NGX_DEBUG_MALLOC)
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358
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45
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646
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46 #define ngx_slab_junk(p, size) ngx_memset(p, 0xA5, size)
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358
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47
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258
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48 #else
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358
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49
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646
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50 #if (NGX_HAVE_DEBUG_MALLOC)
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358
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51
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52 #define ngx_slab_junk(p, size) \
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646
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53 if (ngx_debug_malloc) ngx_memset(p, 0xA5, size)
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358
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54
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55 #else
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56
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258
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57 #define ngx_slab_junk(p, size)
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358
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58
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59 #endif
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60
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258
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61 #endif
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62
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63 static ngx_slab_page_t *ngx_slab_alloc_pages(ngx_slab_pool_t *pool,
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64 ngx_uint_t pages);
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65 static void ngx_slab_free_pages(ngx_slab_pool_t *pool, ngx_slab_page_t *page,
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66 ngx_uint_t pages);
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468
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67 static void ngx_slab_error(ngx_slab_pool_t *pool, ngx_uint_t level,
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68 char *text);
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258
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69
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70
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71 static ngx_uint_t ngx_slab_max_size;
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72 static ngx_uint_t ngx_slab_exact_size;
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73 static ngx_uint_t ngx_slab_exact_shift;
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74
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75
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76 void
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77 ngx_slab_init(ngx_slab_pool_t *pool)
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78 {
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79 u_char *p;
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80 size_t size;
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81 ngx_int_t m;
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82 ngx_uint_t i, n, pages;
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83 ngx_slab_page_t *slots;
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84
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85 /* STUB */
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86 if (ngx_slab_max_size == 0) {
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87 ngx_slab_max_size = ngx_pagesize / 2;
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88 ngx_slab_exact_size = ngx_pagesize / (8 * sizeof(uintptr_t));
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89 for (n = ngx_slab_exact_size; n >>= 1; ngx_slab_exact_shift++) {
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90 /* void */
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91 }
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92 }
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93 /**/
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94
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95 pool->min_size = 1 << pool->min_shift;
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96
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97 p = (u_char *) pool + sizeof(ngx_slab_pool_t);
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98 size = pool->end - p;
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99
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100 ngx_slab_junk(p, size);
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101
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102 slots = (ngx_slab_page_t *) p;
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103 n = ngx_pagesize_shift - pool->min_shift;
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104
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105 for (i = 0; i < n; i++) {
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106 slots[i].slab = 0;
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107 slots[i].next = &slots[i];
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108 slots[i].prev = 0;
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109 }
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110
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111 p += n * sizeof(ngx_slab_page_t);
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112
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348
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113 pages = (ngx_uint_t) (size / (ngx_pagesize + sizeof(ngx_slab_page_t)));
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258
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114
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115 ngx_memzero(p, pages * sizeof(ngx_slab_page_t));
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116
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117 pool->pages = (ngx_slab_page_t *) p;
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118
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119 pool->free.prev = 0;
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120 pool->free.next = (ngx_slab_page_t *) p;
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121
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122 pool->pages->slab = pages;
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123 pool->pages->next = &pool->free;
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124 pool->pages->prev = (uintptr_t) &pool->free;
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125
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126 pool->start = (u_char *)
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274
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127 ngx_align_ptr((uintptr_t) p + pages * sizeof(ngx_slab_page_t),
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258
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128 ngx_pagesize);
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129
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130 m = pages - (pool->end - pool->start) / ngx_pagesize;
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131 if (m > 0) {
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132 pages -= m;
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133 pool->pages->slab = pages;
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134 }
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135
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468
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136 pool->log_ctx = &pool->zero;
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137 pool->zero = '\0';
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258
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138 }
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139
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140
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141 void *
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142 ngx_slab_alloc(ngx_slab_pool_t *pool, size_t size)
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143 {
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272
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144 void *p;
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145
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146 ngx_shmtx_lock(&pool->mutex);
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147
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148 p = ngx_slab_alloc_locked(pool, size);
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149
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150 ngx_shmtx_unlock(&pool->mutex);
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151
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152 return p;
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153 }
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154
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155
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156 void *
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157 ngx_slab_alloc_locked(ngx_slab_pool_t *pool, size_t size)
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158 {
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258
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159 size_t s;
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260
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160 uintptr_t p, n, m, mask, *bitmap;
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161 ngx_uint_t i, slot, shift, map;
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258
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162 ngx_slab_page_t *page, *prev, *slots;
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163
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272
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164 if (size >= ngx_slab_max_size) {
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258
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165
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272
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166 ngx_log_debug1(NGX_LOG_DEBUG_ALLOC, ngx_cycle->log, 0,
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167 "slab alloc: %uz", size);
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168
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258
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169 page = ngx_slab_alloc_pages(pool, (size + ngx_pagesize - 1)
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170 >> ngx_pagesize_shift);
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171 if (page) {
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172 p = (page - pool->pages) << ngx_pagesize_shift;
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173 p += (uintptr_t) pool->start;
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174
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175 } else {
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176 p = 0;
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177 }
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178
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179 goto done;
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180 }
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181
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182 if (size > pool->min_size) {
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183 shift = 1;
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184 for (s = size - 1; s >>= 1; shift++) { /* void */ }
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185 slot = shift - pool->min_shift;
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186
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187 } else {
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188 size = pool->min_size;
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189 shift = pool->min_shift;
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190 slot = 0;
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191 }
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192
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193 ngx_log_debug2(NGX_LOG_DEBUG_ALLOC, ngx_cycle->log, 0,
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194 "slab alloc: %uz slot: %ui", size, slot);
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195
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196 slots = (ngx_slab_page_t *) ((u_char *) pool + sizeof(ngx_slab_pool_t));
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197 page = slots[slot].next;
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198
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199 if (page->next != page) {
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200
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272
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201 if (shift < ngx_slab_exact_shift) {
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258
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202
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203 do {
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204 p = (page - pool->pages) << ngx_pagesize_shift;
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205 bitmap = (uintptr_t *) (pool->start + p);
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206
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207 map = (1 << (ngx_pagesize_shift - shift))
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208 / (sizeof(uintptr_t) * 8);
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209
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210 for (n = 0; n < map; n++) {
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211
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212 if (bitmap[n] != NGX_SLAB_BUSY) {
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213
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214 for (m = 1, i = 0; m; m <<= 1, i++) {
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215 if ((bitmap[n] & m)) {
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216 continue;
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217 }
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218
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219 bitmap[n] |= m;
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272
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220
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221 i = ((n * sizeof(uintptr_t) * 8) << shift)
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222 + (i << shift);
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258
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223
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224 if (bitmap[n] == NGX_SLAB_BUSY) {
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225 for (n = n + 1; n < map; n++) {
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226 if (bitmap[n] != NGX_SLAB_BUSY) {
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227 p = (uintptr_t) bitmap + i;
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228
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229 goto done;
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230 }
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231 }
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232
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233 prev = (ngx_slab_page_t *)
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234 (page->prev & ~NGX_SLAB_PAGE_MASK);
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235 prev->next = page->next;
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236 page->next->prev = page->prev;
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237
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238 page->next = NULL;
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239 page->prev = NGX_SLAB_SMALL;
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240 }
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241
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242 p = (uintptr_t) bitmap + i;
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243
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244 goto done;
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245 }
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246 }
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247 }
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248
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249 page = page->next;
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250
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251 } while (page);
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252
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272
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253 } else if (shift == ngx_slab_exact_shift) {
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258
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254
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255 do {
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256 if (page->slab != NGX_SLAB_BUSY) {
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257
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258 for (m = 1, i = 0; m; m <<= 1, i++) {
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259 if ((page->slab & m)) {
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260 continue;
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261 }
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262
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263 page->slab |= m;
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264
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265 if (page->slab == NGX_SLAB_BUSY) {
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266 prev = (ngx_slab_page_t *)
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267 (page->prev & ~NGX_SLAB_PAGE_MASK);
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268 prev->next = page->next;
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269 page->next->prev = page->prev;
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270
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271 page->next = NULL;
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272 page->prev = NGX_SLAB_EXACT;
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273 }
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274
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275 p = (page - pool->pages) << ngx_pagesize_shift;
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276 p += i << shift;
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277 p += (uintptr_t) pool->start;
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278
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279 goto done;
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280 }
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281 }
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282
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283 page = page->next;
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284
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285 } while (page);
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286
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272
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287 } else { /* shift > ngx_slab_exact_shift */
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258
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288
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289 n = ngx_pagesize_shift - (page->slab & NGX_SLAB_SHIFT_MASK);
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290 n = 1 << n;
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274
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291 n = ((uintptr_t) 1 << n) - 1;
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258
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292 mask = n << NGX_SLAB_MAP_SHIFT;
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293
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294 do {
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295 if ((page->slab & NGX_SLAB_MAP_MASK) != mask) {
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296
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260
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297 for (m = (uintptr_t) 1 << NGX_SLAB_MAP_SHIFT, i = 0;
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258
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298 m & mask;
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299 m <<= 1, i++)
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300 {
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301 if ((page->slab & m)) {
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302 continue;
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303 }
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304
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305 page->slab |= m;
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306
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307 if ((page->slab & NGX_SLAB_MAP_MASK) == mask) {
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308 prev = (ngx_slab_page_t *)
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309 (page->prev & ~NGX_SLAB_PAGE_MASK);
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310 prev->next = page->next;
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311 page->next->prev = page->prev;
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312
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313 page->next = NULL;
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314 page->prev = NGX_SLAB_BIG;
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315 }
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316
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317 p = (page - pool->pages) << ngx_pagesize_shift;
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318 p += i << shift;
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319 p += (uintptr_t) pool->start;
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320
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321 goto done;
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322 }
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323 }
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324
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325 page = page->next;
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326
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327 } while (page);
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328 }
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329 }
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330
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331 page = ngx_slab_alloc_pages(pool, 1);
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332
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333 if (page) {
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272
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334 if (shift < ngx_slab_exact_shift) {
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258
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335 p = (page - pool->pages) << ngx_pagesize_shift;
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336 bitmap = (uintptr_t *) (pool->start + p);
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337
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338 s = 1 << shift;
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339 n = (1 << (ngx_pagesize_shift - shift)) / 8 / s;
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340
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341 if (n == 0) {
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342 n = 1;
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343 }
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344
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345 bitmap[0] = (2 << n) - 1;
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346
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347 map = (1 << (ngx_pagesize_shift - shift)) / (sizeof(uintptr_t) * 8);
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348
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349 for (i = 1; i < map; i++) {
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350 bitmap[i] = 0;
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351 }
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352
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353 page->slab = shift;
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354 page->next = &slots[slot];
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355 page->prev = (uintptr_t) &slots[slot] | NGX_SLAB_SMALL;
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356
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357 slots[slot].next = page;
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358
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359 p = ((page - pool->pages) << ngx_pagesize_shift) + s * n;
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360 p += (uintptr_t) pool->start;
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361
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362 goto done;
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363
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272
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364 } else if (shift == ngx_slab_exact_shift) {
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258
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365
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366 page->slab = 1;
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367 page->next = &slots[slot];
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368 page->prev = (uintptr_t) &slots[slot] | NGX_SLAB_EXACT;
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369
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370 slots[slot].next = page;
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371
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372 p = (page - pool->pages) << ngx_pagesize_shift;
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373 p += (uintptr_t) pool->start;
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374
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375 goto done;
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376
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272
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377 } else { /* shift > ngx_slab_exact_shift */
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258
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378
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260
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379 page->slab = ((uintptr_t) 1 << NGX_SLAB_MAP_SHIFT) | shift;
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258
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380 page->next = &slots[slot];
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381 page->prev = (uintptr_t) &slots[slot] | NGX_SLAB_BIG;
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382
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383 slots[slot].next = page;
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384
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385 p = (page - pool->pages) << ngx_pagesize_shift;
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386 p += (uintptr_t) pool->start;
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387
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388 goto done;
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389 }
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390 }
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391
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392 p = 0;
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393
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394 done:
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395
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396 ngx_log_debug1(NGX_LOG_DEBUG_ALLOC, ngx_cycle->log, 0, "slab alloc: %p", p);
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397
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398 return (void *) p;
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399 }
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400
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401
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402 void
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403 ngx_slab_free(ngx_slab_pool_t *pool, void *p)
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404 {
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272
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405 ngx_shmtx_lock(&pool->mutex);
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406
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407 ngx_slab_free_locked(pool, p);
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408
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409 ngx_shmtx_unlock(&pool->mutex);
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410 }
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411
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412
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413 void
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414 ngx_slab_free_locked(ngx_slab_pool_t *pool, void *p)
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415 {
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258
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416 size_t size;
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274
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417 uintptr_t slab, m, *bitmap;
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418 ngx_uint_t n, type, slot, shift, map;
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258
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419 ngx_slab_page_t *slots, *page;
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420
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421 ngx_log_debug1(NGX_LOG_DEBUG_ALLOC, ngx_cycle->log, 0, "slab free: %p", p);
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422
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423 if ((u_char *) p < pool->start || (u_char *) p > pool->end) {
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468
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424 ngx_slab_error(pool, NGX_LOG_ALERT, "ngx_slab_free(): outside of pool");
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258
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425 goto fail;
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426 }
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427
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428 n = ((u_char *) p - pool->start) >> ngx_pagesize_shift;
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429 page = &pool->pages[n];
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430 slab = page->slab;
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431 type = page->prev & NGX_SLAB_PAGE_MASK;
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432
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433 switch (type) {
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434
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435 case NGX_SLAB_SMALL:
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436
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437 shift = slab & NGX_SLAB_SHIFT_MASK;
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438 size = 1 << shift;
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439
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440 if ((uintptr_t) p & (size - 1)) {
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441 goto wrong_chunk;
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442 }
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443
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444 n = ((uintptr_t) p & (ngx_pagesize - 1)) >> shift;
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274
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445 m = (uintptr_t) 1 << (n & (sizeof(uintptr_t) * 8 - 1));
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258
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446 n /= (sizeof(uintptr_t) * 8);
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447 bitmap = (uintptr_t *) ((uintptr_t) p & ~(ngx_pagesize - 1));
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448
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449 if (bitmap[n] & m) {
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450
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451 if (page->next == NULL) {
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452 slots = (ngx_slab_page_t *)
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453 ((u_char *) pool + sizeof(ngx_slab_pool_t));
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454 slot = shift - pool->min_shift;
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455
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456 page->next = slots[slot].next;
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457 slots[slot].next = page;
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458
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459 page->prev = (uintptr_t) &slots[slot] | NGX_SLAB_SMALL;
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460 page->next->prev = (uintptr_t) page | NGX_SLAB_SMALL;
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461 }
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462
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463 bitmap[n] &= ~m;
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464
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465 n = (1 << (ngx_pagesize_shift - shift)) / 8 / (1 << shift);
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466
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467 if (n == 0) {
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468 n = 1;
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469 }
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470
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274
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471 if (bitmap[0] & ~(((uintptr_t) 1 << n) - 1)) {
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258
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472 goto done;
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473 }
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474
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475 map = (1 << (ngx_pagesize_shift - shift)) / (sizeof(uintptr_t) * 8);
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476
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477 for (n = 1; n < map; n++) {
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478 if (bitmap[n]) {
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479 goto done;
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480 }
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481 }
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482
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483 ngx_slab_free_pages(pool, page, 1);
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484
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485 goto done;
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486 }
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487
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488 goto chunk_already_free;
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489
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490 case NGX_SLAB_EXACT:
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491
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274
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492 m = (uintptr_t) 1 <<
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493 (((uintptr_t) p & (ngx_pagesize - 1)) >> ngx_slab_exact_shift);
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258
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494 size = ngx_slab_exact_size;
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495
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496 if ((uintptr_t) p & (size - 1)) {
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497 goto wrong_chunk;
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498 }
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499
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500 if (slab & m) {
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501 if (slab == NGX_SLAB_BUSY) {
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502 slots = (ngx_slab_page_t *)
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503 ((u_char *) pool + sizeof(ngx_slab_pool_t));
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504 slot = ngx_slab_exact_shift - pool->min_shift;
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505
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506 page->next = slots[slot].next;
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507 slots[slot].next = page;
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508
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509 page->prev = (uintptr_t) &slots[slot] | NGX_SLAB_EXACT;
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510 page->next->prev = (uintptr_t) page | NGX_SLAB_EXACT;
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511 }
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512
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513 page->slab &= ~m;
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514
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515 if (page->slab) {
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516 goto done;
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517 }
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518
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519 ngx_slab_free_pages(pool, page, 1);
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520
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521 goto done;
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522 }
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523
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524 goto chunk_already_free;
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525
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526 case NGX_SLAB_BIG:
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527
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528 shift = slab & NGX_SLAB_SHIFT_MASK;
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529 size = 1 << shift;
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530
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531 if ((uintptr_t) p & (size - 1)) {
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532 goto wrong_chunk;
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533 }
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534
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274
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535 m = (uintptr_t) 1 << ((((uintptr_t) p & (ngx_pagesize - 1)) >> shift)
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536 + NGX_SLAB_MAP_SHIFT);
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258
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537
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538 if (slab & m) {
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539
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540 if (page->next == NULL) {
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541 slots = (ngx_slab_page_t *)
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542 ((u_char *) pool + sizeof(ngx_slab_pool_t));
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543 slot = shift - pool->min_shift;
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544
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545 page->next = slots[slot].next;
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546 slots[slot].next = page;
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547
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548 page->prev = (uintptr_t) &slots[slot] | NGX_SLAB_BIG;
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549 page->next->prev = (uintptr_t) page | NGX_SLAB_BIG;
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550 }
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551
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552 page->slab &= ~m;
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553
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554 if (page->slab & NGX_SLAB_MAP_MASK) {
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555 goto done;
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556 }
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557
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558 ngx_slab_free_pages(pool, page, 1);
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559
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560 goto done;
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561 }
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562
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563 goto chunk_already_free;
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564
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565 case NGX_SLAB_PAGE:
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566
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567 if ((uintptr_t) p & (ngx_pagesize - 1)) {
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568 goto wrong_chunk;
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569 }
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570
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571 if (slab == NGX_SLAB_PAGE_FREE) {
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468
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572 ngx_slab_error(pool, NGX_LOG_ALERT,
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573 "ngx_slab_free(): page is already free");
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258
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574 goto fail;
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575 }
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576
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577 if (slab == NGX_SLAB_PAGE_BUSY) {
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468
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578 ngx_slab_error(pool, NGX_LOG_ALERT,
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579 "ngx_slab_free(): pointer to wrong page");
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258
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580 goto fail;
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581 }
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582
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583 n = ((u_char *) p - pool->start) >> ngx_pagesize_shift;
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584 size = slab & ~NGX_SLAB_PAGE_START;
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585
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586 ngx_slab_free_pages(pool, &pool->pages[n], size);
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587
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480
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588 ngx_slab_junk(p, size << ngx_pagesize_shift);
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258
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589
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480
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590 return;
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258
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591 }
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592
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593 /* not reached */
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594
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595 return;
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596
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597 done:
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598
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599 ngx_slab_junk(p, size);
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600
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601 return;
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602
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603 wrong_chunk:
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604
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468
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605 ngx_slab_error(pool, NGX_LOG_ALERT,
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606 "ngx_slab_free(): pointer to wrong chunk");
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258
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607
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608 goto fail;
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609
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610 chunk_already_free:
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611
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468
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612 ngx_slab_error(pool, NGX_LOG_ALERT,
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613 "ngx_slab_free(): chunk is already free");
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258
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614
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615 fail:
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616
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617 return;
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618 }
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619
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620
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621 static ngx_slab_page_t *
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622 ngx_slab_alloc_pages(ngx_slab_pool_t *pool, ngx_uint_t pages)
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623 {
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624 ngx_slab_page_t *page, *p;
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625
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626 for (page = pool->free.next; page != &pool->free; page = page->next) {
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627
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628 if (page->slab >= pages) {
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629
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630 if (page->slab > pages) {
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631 page[pages].slab = page->slab - pages;
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632 page[pages].next = page->next;
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633 page[pages].prev = page->prev;
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634
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635 p = (ngx_slab_page_t *) page->prev;
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636 p->next = &page[pages];
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637 page->next->prev = (uintptr_t) &page[pages];
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638
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639 } else {
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640 p = (ngx_slab_page_t *) page->prev;
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641 p->next = page->next;
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642 page->next->prev = page->prev;
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643 }
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644
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645 page->slab = pages | NGX_SLAB_PAGE_START;
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646 page->next = NULL;
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647 page->prev = NGX_SLAB_PAGE;
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648
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649 if (--pages == 0) {
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650 return page;
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651 }
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652
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653 for (p = page + 1; pages; pages--) {
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654 p->slab = NGX_SLAB_PAGE_BUSY;
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655 p->next = NULL;
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656 p->prev = NGX_SLAB_PAGE;
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657 p++;
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658 }
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659
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660 return page;
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661 }
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662 }
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663
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468
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664 ngx_slab_error(pool, NGX_LOG_CRIT, "ngx_slab_alloc() failed: no memory");
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272
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665
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258
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666 return NULL;
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667 }
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668
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669
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670 static void
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671 ngx_slab_free_pages(ngx_slab_pool_t *pool, ngx_slab_page_t *page,
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672 ngx_uint_t pages)
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673 {
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674 ngx_slab_page_t *prev;
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675
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676 page->slab = pages--;
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677
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678 if (pages) {
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679 ngx_memzero(&page[1], pages * sizeof(ngx_slab_page_t));
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680 }
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681
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272
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682 if (page->next) {
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683 prev = (ngx_slab_page_t *) (page->prev & ~NGX_SLAB_PAGE_MASK);
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684 prev->next = page->next;
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685 page->next->prev = page->prev;
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686 }
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258
|
687
|
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272
|
688 page->prev = (uintptr_t) &pool->free;
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258
|
689 page->next = pool->free.next;
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272
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690
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|
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691 page->next->prev = (uintptr_t) page;
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|
692
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258
|
693 pool->free.next = page;
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694 }
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468
|
695
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696
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697 static void
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698 ngx_slab_error(ngx_slab_pool_t *pool, ngx_uint_t level, char *text)
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699 {
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700 ngx_log_error(level, ngx_cycle->log, 0, "%s%s", text, pool->log_ctx);
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701 }
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