Mercurial > hg > nginx-quic
annotate src/core/ngx_crc.h @ 4385:70ba81827472
Cache locks initial implementation.
New directives: proxy_cache_lock on/off, proxy_cache_lock_timeout. With
proxy_cache_lock set to on, only one request will be allowed to go to
upstream for a particular cache item. Others will wait for a response
to appear in cache (or cache lock released) up to proxy_cache_lock_timeout.
Waiting requests will recheck if they have cached response ready (or are
allowed to run) every 500ms.
Note: we intentionally don't intercept NGX_DECLINED possibly returned by
ngx_http_file_cache_read(). This needs more work (possibly safe, but needs
further investigation). Anyway, it's exceptional situation.
Note: probably there should be a way to disable caching of responses
if there is already one request fetching resource to cache (without waiting
at all). Two possible ways include another cache lock option ("no_cache")
or using proxy_no_cache with some supplied variable.
Note: probably there should be a way to lock updating requests as well. For
now "proxy_cache_use_stale updating" is available.
author | Maxim Dounin <mdounin@mdounin.ru> |
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date | Mon, 26 Dec 2011 11:15:23 +0000 |
parents | 99858705b03f |
children | d620f497c50f |
rev | line source |
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2 /* |
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3 * Copyright (C) Igor Sysoev |
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4 */ |
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7 #ifndef _NGX_CRC_H_INCLUDED_ |
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8 #define _NGX_CRC_H_INCLUDED_ |
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792 | 11 #include <ngx_config.h> |
12 #include <ngx_core.h> | |
13 | |
14 | |
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15 /* 32-bit crc16 */ |
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16 |
776 | 17 static ngx_inline uint32_t |
789 | 18 ngx_crc(u_char *data, size_t len) |
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19 { |
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20 uint32_t sum; |
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22 for (sum = 0; len; len--) { |
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24 /* |
776 | 25 * gcc 2.95.2 x86 and icc 7.1.006 compile |
26 * that operator into the single "rol" opcode, | |
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27 * msvc 6.0sp2 compiles it into four opcodes. |
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28 */ |
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29 sum = sum >> 1 | sum << 31; |
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31 sum += *data++; |
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32 } |
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34 return sum; |
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35 } |
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38 #endif /* _NGX_CRC_H_INCLUDED_ */ |