248 lines
9.6 KiB
C
248 lines
9.6 KiB
C
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/*
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* Copyright (C) Igor Sysoev
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* Copyright (C) NGINX, Inc.
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*/
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#ifndef _NXT_BUF_H_INCLUDED_
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#define _NXT_BUF_H_INCLUDED_
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/*
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* There are four types of buffers. They are different sizes, so they
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* should be allocated by appropriate nxt_buf_XXX_alloc() function.
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*
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* 1) Memory-only buffers, their size is less than nxt_buf_t size, it
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* is equal to offsetof(nxt_buf_t, file_pos), that is it is nxt_buf_t
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* without file and mmap part. The buffers are frequently used, so
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* the reduction allows to save 20-32 bytes depending on platform.
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*
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* 2) Memory/file buffers, on Unix their size is exactly nxt_buf_t size,
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* since nxt_mem_map_file_ctx_t() is empty macro. On Windows the size
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* equals offsetof(nxt_buf_t, mmap), that is it is nxt_buf_t without
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* memory map context part. The buffers can contain both memory and
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* file pointers at once, or only memory or file pointers.
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*
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* 3) Memory mapped buffers are similar to the memory/file buffers. Their
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* size is exactly nxt_buf_t size. The buffers can contain both memory
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* and file pointers at once, or only memory or file pointers. If a
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* buffer is not currently mapped in memory, its mapping size is stored
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* in the mem.end field and available via nxt_buf_mem_size() macro.
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*
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* 4) Sync buffers, their size is the same size as memory-only buffers
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* size. A sync buffer can be smaller but for memory pool cache
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* purpose it is better to allocate it as frequently used memory-only
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* buffer. The buffers are used to synchronize pipeline processing
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* completion, because data buffers in the pipeline can be completed
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* and freed before their final output will even be passed to a peer.
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* For this purpose a sync buffer is allocated with the stop flag which
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* stops buffer chain completion processing on the sync buffer in
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* nxt_sendbuf_update() and nxt_sendbuf_completion().
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* Clearing the stop flag allows to continue completion processing.
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*
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* The last flag means the end of the output and must be set only
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* in a sync buffer. The last flag is not permitted in memory and
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* file buffers since it requires special handling while conversion
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* one buffer to another.
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*
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* The nxt_buf_used_size() macro treats a sync buffer as a memory-only
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* buffer which has NULL pointers, thus the buffer content size is zero.
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* If allocated size of sync buffer would be lesser than memory-only
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* buffer, then the special memory flag would be required because
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* currently presence of memory part is indicated by non-NULL pointer
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* to a content in memory.
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*
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* All types of buffers can have the flush flag that means the buffer
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* should be sent as much as possible.
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*/
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typedef struct {
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u_char *pos;
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u_char *free;
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u_char *start;
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u_char *end;
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} nxt_buf_mem_t;
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struct nxt_buf_s {
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void *data;
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nxt_work_handler_t completion_handler;
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nxt_buf_t *parent;
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/*
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* The next link, flags, and nxt_buf_mem_t should
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* reside together to improve cache locality.
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*/
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nxt_buf_t *next;
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uint32_t retain;
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/*
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* Used by nxt_mem_cache_free() to return buffer
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* in appropriate memory pool cache.
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*/
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uint8_t size;
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uint8_t is_file; /* 1 bit */
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uint16_t is_mmap:1;
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uint16_t is_sync:1;
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uint16_t is_nobuf:1;
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uint16_t is_flush:1;
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uint16_t is_last:1;
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nxt_buf_mem_t mem;
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/* The file and mmap parts are not allocated by nxt_buf_mem_alloc(). */
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nxt_file_t *file;
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nxt_off_t file_pos;
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nxt_off_t file_end;
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/* The mmap part is not allocated by nxt_buf_file_alloc(). */
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nxt_mem_map_file_ctx_t (mmap)
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};
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#define NXT_BUF_MEM_SIZE offsetof(nxt_buf_t, file)
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#define NXT_BUF_SYNC_SIZE NXT_BUF_MEM_SIZE
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#define NXT_BUF_MMAP_SIZE sizeof(nxt_buf_t)
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#define NXT_BUF_FILE_SIZE sizeof(nxt_buf_t)
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#define NXT_BUF_SYNC_NOBUF 1
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#define NXT_BUF_SYNC_FLUSH 2
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#define NXT_BUF_SYNC_LAST 4
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#define \
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nxt_buf_is_mem(b) \
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((b)->mem.pos != NULL)
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#define \
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nxt_buf_is_file(b) \
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((b)->is_file)
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#define \
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nxt_buf_set_file(b) \
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(b)->is_file = 1
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#define \
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nxt_buf_clear_file(b) \
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(b)->is_file = 0
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#define \
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nxt_buf_is_mmap(b) \
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((b)->is_mmap)
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#define \
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nxt_buf_set_mmap(b) \
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(b)->is_mmap = 1
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#define \
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nxt_buf_clear_mmap(b) \
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(b)->is_mmap = 0
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#define \
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nxt_buf_is_sync(b) \
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((b)->is_sync)
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#define \
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nxt_buf_set_sync(b) \
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(b)->is_sync = 1
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#define \
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nxt_buf_clear_sync(b) \
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(b)->is_sync = 0
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#define \
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nxt_buf_is_nobuf(b) \
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((b)->is_nobuf)
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#define \
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nxt_buf_set_nobuf(b) \
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(b)->is_nobuf = 1
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#define \
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nxt_buf_clear_nobuf(b) \
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(b)->is_nobuf = 0
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#define \
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nxt_buf_is_flush(b) \
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((b)->is_flush)
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#define \
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nxt_buf_set_flush(b) \
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(b)->is_flush = 1
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#define \
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nxt_buf_clear_flush(b) \
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(b)->is_flush = 0
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#define \
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nxt_buf_is_last(b) \
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((b)->is_last)
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#define \
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nxt_buf_set_last(b) \
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(b)->is_last = 1
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#define \
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nxt_buf_clear_last(b) \
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(b)->is_last = 0
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#define \
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nxt_buf_mem_set_size(bm, size) \
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do { \
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(bm)->start = 0; \
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(bm)->end = (void *) size; \
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} while (0)
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#define \
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nxt_buf_mem_size(bm) \
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((bm)->end - (bm)->start)
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#define \
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nxt_buf_mem_used_size(bm) \
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((bm)->free - (bm)->pos)
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#define \
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nxt_buf_mem_free_size(bm) \
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((bm)->end - (bm)->free)
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#define \
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nxt_buf_used_size(b) \
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(nxt_buf_is_file(b) ? (b)->file_end - (b)->file_pos: \
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nxt_buf_mem_used_size(&(b)->mem))
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NXT_EXPORT void nxt_buf_mem_init(nxt_buf_t *b, void *start, size_t size);
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NXT_EXPORT nxt_buf_t *nxt_buf_mem_alloc(nxt_mem_pool_t *mp, size_t size,
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nxt_uint_t flags);
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NXT_EXPORT nxt_buf_t *nxt_buf_file_alloc(nxt_mem_pool_t *mp, size_t size,
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nxt_uint_t flags);
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NXT_EXPORT nxt_buf_t *nxt_buf_mmap_alloc(nxt_mem_pool_t *mp, size_t size);
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NXT_EXPORT nxt_buf_t *nxt_buf_sync_alloc(nxt_mem_pool_t *mp, nxt_uint_t flags);
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#define \
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nxt_buf_free(mp, b) \
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nxt_mem_cache_free0((mp), (b), (b)->size)
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NXT_EXPORT void nxt_buf_chain_add(nxt_buf_t **head, nxt_buf_t *in);
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NXT_EXPORT size_t nxt_buf_chain_length(nxt_buf_t *b);
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#endif /* _NXT_BUF_H_INCLIDED_ */
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