1 2 /* 3 * Copyright (C) Igor Sysoev 4 * Copyright (C) NGINX, Inc. 5 */ 6 7 #ifndef _NXT_BUF_H_INCLUDED_ 8 #define _NXT_BUF_H_INCLUDED_ 9 10 11 /* 12 * There are four types of buffers. They are different sizes, so they 13 * should be allocated by appropriate nxt_buf_XXX_alloc() function. 14 * 15 * 1) Memory-only buffers, their size is less than nxt_buf_t size, it 16 * is equal to offsetof(nxt_buf_t, file_pos), that is it is nxt_buf_t 17 * without file and mmap part. The buffers are frequently used, so 18 * the reduction allows to save 20-32 bytes depending on platform. 19 * 20 * 2) Memory/file buffers, on Unix their size is exactly nxt_buf_t size, 21 * since nxt_mem_map_file_ctx_t() is empty macro. On Windows the size 22 * equals offsetof(nxt_buf_t, mmap), that is it is nxt_buf_t without 23 * memory map context part. The buffers can contain both memory and 24 * file pointers at once, or only memory or file pointers. 25 * 26 * 3) Memory mapped buffers are similar to the memory/file buffers. Their 27 * size is exactly nxt_buf_t size. The buffers can contain both memory 28 * and file pointers at once, or only memory or file pointers. If a 29 * buffer is not currently mapped in memory, its mapping size is stored 30 * in the mem.end field and available via nxt_buf_mem_size() macro. 31 * 32 * 4) Sync buffers, their size is the same size as memory-only buffers 33 * size. A sync buffer can be smaller but for memory pool cache 34 * purpose it is better to allocate it as frequently used memory-only 35 * buffer. The buffers are used to synchronize pipeline processing 36 * completion, because data buffers in the pipeline can be completed 37 * and freed before their final output will even be passed to a peer. 38 * For this purpose a sync buffer is allocated with the stop flag which 39 * stops buffer chain completion processing on the sync buffer in 40 * nxt_sendbuf_update() and nxt_sendbuf_completion(). 41 * Clearing the stop flag allows to continue completion processing. 42 * 43 * The last flag means the end of the output and must be set only 44 * in a sync buffer. The last flag is not permitted in memory and 45 * file buffers since it requires special handling while conversion 46 * one buffer to another. 47 * 48 * The nxt_buf_used_size() macro treats a sync buffer as a memory-only 49 * buffer which has NULL pointers, thus the buffer content size is zero. 50 * If allocated size of sync buffer would be lesser than memory-only 51 * buffer, then the special memory flag would be required because 52 * currently presence of memory part is indicated by non-NULL pointer 53 * to a content in memory. 54 * 55 * All types of buffers can have the flush flag that means the buffer 56 * should be sent as much as possible. 57 */ 58 59 typedef struct { 60 u_char *pos; 61 u_char *free; 62 u_char *start; 63 u_char *end; 64 } nxt_buf_mem_t; 65 66 67 struct nxt_buf_s { 68 void *data; 69 nxt_work_handler_t completion_handler; 70 nxt_buf_t *parent; 71 72 /* 73 * The next link, flags, and nxt_buf_mem_t should 74 * reside together to improve cache locality. 75 */ 76 nxt_buf_t *next; 77 78 uint32_t retain; 79 /* 80 * Used by nxt_mem_cache_free() to return buffer 81 * in appropriate memory pool cache. 82 */ 83 uint8_t size; 84 85 uint8_t is_file; /* 1 bit */ 86 87 uint16_t is_mmap:1; 88 89 uint16_t is_sync:1; 90 uint16_t is_nobuf:1; 91 uint16_t is_flush:1; 92 uint16_t is_last:1; 93 94 nxt_buf_mem_t mem; 95 96 /* The file and mmap parts are not allocated by nxt_buf_mem_alloc(). */ 97 nxt_file_t *file; 98 nxt_off_t file_pos; 99 nxt_off_t file_end; 100 101 /* The mmap part is not allocated by nxt_buf_file_alloc(). */ 102 nxt_mem_map_file_ctx_t (mmap) 103 }; 104 105 106 #define NXT_BUF_MEM_SIZE offsetof(nxt_buf_t, file) 107 #define NXT_BUF_SYNC_SIZE NXT_BUF_MEM_SIZE 108 #define NXT_BUF_MMAP_SIZE sizeof(nxt_buf_t) 109 #define NXT_BUF_FILE_SIZE sizeof(nxt_buf_t) 110 111 112 #define NXT_BUF_SYNC_NOBUF 1 113 #define NXT_BUF_SYNC_FLUSH 2 114 #define NXT_BUF_SYNC_LAST 4 115 116 117 #define \ 118 nxt_buf_is_mem(b) \ 119 ((b)->mem.pos != NULL) 120 121 122 #define \ 123 nxt_buf_is_file(b) \ 124 ((b)->is_file) 125 126 #define \ 127 nxt_buf_set_file(b) \ 128 (b)->is_file = 1 129 130 #define \ 131 nxt_buf_clear_file(b) \ 132 (b)->is_file = 0 133 134 135 #define \ 136 nxt_buf_is_mmap(b) \ 137 ((b)->is_mmap) 138 139 #define \ 140 nxt_buf_set_mmap(b) \ 141 (b)->is_mmap = 1 142 143 #define \ 144 nxt_buf_clear_mmap(b) \ 145 (b)->is_mmap = 0 146 147 148 #define \ 149 nxt_buf_is_sync(b) \ 150 ((b)->is_sync) 151 152 #define \ 153 nxt_buf_set_sync(b) \ 154 (b)->is_sync = 1 155 156 #define \ 157 nxt_buf_clear_sync(b) \ 158 (b)->is_sync = 0 159 160 161 #define \ 162 nxt_buf_is_nobuf(b) \ 163 ((b)->is_nobuf) 164 165 #define \ 166 nxt_buf_set_nobuf(b) \ 167 (b)->is_nobuf = 1 168 169 #define \ 170 nxt_buf_clear_nobuf(b) \ 171 (b)->is_nobuf = 0 172 173 174 #define \ 175 nxt_buf_is_flush(b) \ 176 ((b)->is_flush) 177 178 #define \ 179 nxt_buf_set_flush(b) \ 180 (b)->is_flush = 1 181 182 #define \ 183 nxt_buf_clear_flush(b) \ 184 (b)->is_flush = 0 185 186 187 #define \ 188 nxt_buf_is_last(b) \ 189 ((b)->is_last) 190 191 #define \ 192 nxt_buf_set_last(b) \ 193 (b)->is_last = 1 194 195 #define \ 196 nxt_buf_clear_last(b) \ 197 (b)->is_last = 0 198 199 200 #define \ 201 nxt_buf_mem_set_size(bm, size) \ 202 do { \ 203 (bm)->start = 0; \ 204 (bm)->end = (void *) size; \ 205 } while (0) 206 207 208 #define \ 209 nxt_buf_mem_size(bm) \ 210 ((bm)->end - (bm)->start) 211 212 213 #define \ 214 nxt_buf_mem_used_size(bm) \ 215 ((bm)->free - (bm)->pos) 216 217 218 #define \ 219 nxt_buf_mem_free_size(bm) \ 220 ((bm)->end - (bm)->free) 221 222 223 #define \ 224 nxt_buf_used_size(b) \ 225 (nxt_buf_is_file(b) ? (b)->file_end - (b)->file_pos: \ 226 nxt_buf_mem_used_size(&(b)->mem)) 227 228 229 NXT_EXPORT nxt_buf_t *nxt_buf_mem_alloc(nxt_mem_pool_t *mp, size_t size, 230 nxt_uint_t flags); 231 NXT_EXPORT nxt_buf_t *nxt_buf_file_alloc(nxt_mem_pool_t *mp, size_t size, 232 nxt_uint_t flags); 233 NXT_EXPORT nxt_buf_t *nxt_buf_mmap_alloc(nxt_mem_pool_t *mp, size_t size); 234 NXT_EXPORT nxt_buf_t *nxt_buf_sync_alloc(nxt_mem_pool_t *mp, nxt_uint_t flags); 235 236 237 #define \ 238 nxt_buf_free(mp, b) \ 239 nxt_mem_cache_free0((mp), (b), (b)->size) 240 241 242 NXT_EXPORT void nxt_buf_chain_add(nxt_buf_t **head, nxt_buf_t *in); 243 NXT_EXPORT size_t nxt_buf_chain_length(nxt_buf_t *b); 244 245 246 #endif /* _NXT_BUF_H_INCLIDED_ */ 247