Mercurial > hg > nginx
annotate src/core/ngx_crc.h @ 8078:5244d3b165ff
SSL: single allocation in session cache on 32-bit platforms.
Given the present typical SSL session sizes, on 32-bit platforms it is
now beneficial to store all data in a single allocation, since rbtree
node + session id + ASN1 representation of a session takes 256 bytes of
shared memory (36 + 32 + 150 = about 218 bytes plus SNI server name).
Storing all data in a single allocation is beneficial for SNI names up to
about 40 characters long and makes it possible to store about 4000 sessions
in one megabyte (instead of about 3000 sessions now). This also slightly
simplifies the code.
author | Maxim Dounin <mdounin@mdounin.ru> |
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date | Wed, 12 Oct 2022 20:14:40 +0300 |
parents | d620f497c50f |
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2 /* |
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3 * Copyright (C) Igor Sysoev |
4412 | 4 * Copyright (C) Nginx, Inc. |
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5 */ |
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8 #ifndef _NGX_CRC_H_INCLUDED_ |
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9 #define _NGX_CRC_H_INCLUDED_ |
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792 | 12 #include <ngx_config.h> |
13 #include <ngx_core.h> | |
14 | |
15 | |
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16 /* 32-bit crc16 */ |
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17 |
776 | 18 static ngx_inline uint32_t |
789 | 19 ngx_crc(u_char *data, size_t len) |
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20 { |
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21 uint32_t sum; |
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23 for (sum = 0; len; len--) { |
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25 /* |
776 | 26 * gcc 2.95.2 x86 and icc 7.1.006 compile |
27 * that operator into the single "rol" opcode, | |
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28 * msvc 6.0sp2 compiles it into four opcodes. |
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29 */ |
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30 sum = sum >> 1 | sum << 31; |
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31 |
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32 sum += *data++; |
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33 } |
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34 |
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35 return sum; |
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36 } |
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37 |
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38 |
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39 #endif /* _NGX_CRC_H_INCLUDED_ */ |