Mercurial > hg > nginx-quic
annotate src/http/modules/ngx_http_empty_gif_module.c @ 4207:4fc91bae6f83
Better recheck of dead upstream servers.
Previously nginx used to mark backend again as live as soon as fail_timeout
passes (10s by default) since last failure. On the other hand, detecting
dead backend takes up to 60s (proxy_connect_timeout) in typical situation
"backend is down and doesn't respond to any packets". This resulted in
suboptimal behaviour in the above situation (up to 23% of requests were
directed to dead backend with default settings).
More detailed description of the problem may be found here (in Russian):
http://mailman.nginx.org/pipermail/nginx-ru/2011-August/042172.html
Fix is to only allow one request after fail_timeout passes, and
mark backend as "live" only if this request succeeds.
Note that with new code backend will not be marked "live" unless "check"
request is completed, and this may take a while in some specific workloads
(e.g. streaming). This is believed to be acceptable.
author | Maxim Dounin <mdounin@mdounin.ru> |
---|---|
date | Wed, 12 Oct 2011 14:22:48 +0000 |
parents | 18f1cb12c6d7 |
children | d620f497c50f |
rev | line source |
---|---|
577 | 1 |
2 /* | |
3 * Copyright (C) Igor Sysoev | |
4 */ | |
5 | |
6 #include <ngx_config.h> | |
7 #include <ngx_core.h> | |
8 #include <ngx_http.h> | |
9 | |
10 | |
11 static char *ngx_http_empty_gif(ngx_conf_t *cf, ngx_command_t *cmd, | |
12 void *conf); | |
13 | |
14 static ngx_command_t ngx_http_empty_gif_commands[] = { | |
15 | |
16 { ngx_string("empty_gif"), | |
17 NGX_HTTP_LOC_CONF|NGX_CONF_NOARGS, | |
18 ngx_http_empty_gif, | |
19 0, | |
20 0, | |
21 NULL }, | |
22 | |
23 ngx_null_command | |
24 }; | |
25 | |
26 | |
27 /* the minimal single pixel transparent GIF, 43 bytes */ | |
28 | |
29 static u_char ngx_empty_gif[] = { | |
30 | |
581 | 31 'G', 'I', 'F', '8', '9', 'a', /* header */ |
577 | 32 |
581 | 33 /* logical screen descriptor */ |
34 0x01, 0x00, /* logical screen width */ | |
35 0x01, 0x00, /* logical screen height */ | |
36 0x80, /* global 1-bit color table */ | |
37 0x01, /* background color #1 */ | |
38 0x00, /* no aspect ratio */ | |
577 | 39 |
581 | 40 /* global color table */ |
41 0x00, 0x00, 0x00, /* #0: black */ | |
42 0xff, 0xff, 0xff, /* #1: white */ | |
577 | 43 |
581 | 44 /* graphic control extension */ |
45 0x21, /* extension introducer */ | |
46 0xf9, /* graphic control label */ | |
47 0x04, /* block size */ | |
48 0x01, /* transparent color is given, */ | |
49 /* no disposal specified, */ | |
50 /* user input is not expected */ | |
51 0x00, 0x00, /* delay time */ | |
52 0x01, /* transparent color #1 */ | |
53 0x00, /* block terminator */ | |
577 | 54 |
581 | 55 /* image descriptor */ |
56 0x2c, /* image separator */ | |
57 0x00, 0x00, /* image left position */ | |
58 0x00, 0x00, /* image top position */ | |
59 0x01, 0x00, /* image width */ | |
60 0x01, 0x00, /* image height */ | |
61 0x00, /* no local color table, no interlaced */ | |
577 | 62 |
581 | 63 /* table based image data */ |
64 0x02, /* LZW minimum code size, */ | |
65 /* must be at least 2-bit */ | |
66 0x02, /* block size */ | |
577 | 67 0x4c, 0x01, /* compressed bytes 01_001_100, 0000000_1 */ |
581 | 68 /* 100: clear code */ |
69 /* 001: 1 */ | |
70 /* 101: end of information code */ | |
71 0x00, /* block terminator */ | |
577 | 72 |
581 | 73 0x3B /* trailer */ |
577 | 74 }; |
75 | |
76 | |
667 | 77 static ngx_http_module_t ngx_http_empty_gif_module_ctx = { |
577 | 78 NULL, /* preconfiguration */ |
79 NULL, /* postconfiguration */ | |
80 | |
81 NULL, /* create main configuration */ | |
82 NULL, /* init main configuration */ | |
83 | |
84 NULL, /* create server configuration */ | |
85 NULL, /* merge server configuration */ | |
86 | |
87 NULL, /* create location configuration */ | |
88 NULL /* merge location configuration */ | |
89 }; | |
90 | |
91 | |
92 ngx_module_t ngx_http_empty_gif_module = { | |
93 NGX_MODULE_V1, | |
94 &ngx_http_empty_gif_module_ctx, /* module context */ | |
95 ngx_http_empty_gif_commands, /* module directives */ | |
96 NGX_HTTP_MODULE, /* module type */ | |
97 NULL, /* init master */ | |
98 NULL, /* init module */ | |
99 NULL, /* init process */ | |
100 NULL, /* init thread */ | |
101 NULL, /* exit thread */ | |
102 NULL, /* exit process */ | |
103 NULL, /* exit master */ | |
104 NGX_MODULE_V1_PADDING | |
105 }; | |
106 | |
107 | |
3635
c0113b6648de
use ngx_http_send_response() in empty_gif
Igor Sysoev <igor@sysoev.ru>
parents:
3516
diff
changeset
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108 static ngx_str_t ngx_http_gif_type = ngx_string("image/gif"); |
c0113b6648de
use ngx_http_send_response() in empty_gif
Igor Sysoev <igor@sysoev.ru>
parents:
3516
diff
changeset
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109 |
c0113b6648de
use ngx_http_send_response() in empty_gif
Igor Sysoev <igor@sysoev.ru>
parents:
3516
diff
changeset
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110 |
577 | 111 static ngx_int_t |
112 ngx_http_empty_gif_handler(ngx_http_request_t *r) | |
113 { | |
3635
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use ngx_http_send_response() in empty_gif
Igor Sysoev <igor@sysoev.ru>
parents:
3516
diff
changeset
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114 ngx_http_complex_value_t cv; |
577 | 115 |
645 | 116 if (!(r->method & (NGX_HTTP_GET|NGX_HTTP_HEAD))) { |
577 | 117 return NGX_HTTP_NOT_ALLOWED; |
118 } | |
119 | |
3635
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use ngx_http_send_response() in empty_gif
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parents:
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120 ngx_memzero(&cv, sizeof(ngx_http_complex_value_t)); |
577 | 121 |
3635
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use ngx_http_send_response() in empty_gif
Igor Sysoev <igor@sysoev.ru>
parents:
3516
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changeset
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122 cv.value.len = sizeof(ngx_empty_gif); |
c0113b6648de
use ngx_http_send_response() in empty_gif
Igor Sysoev <igor@sysoev.ru>
parents:
3516
diff
changeset
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123 cv.value.data = ngx_empty_gif; |
577 | 124 r->headers_out.last_modified_time = 23349600; |
125 | |
3635
c0113b6648de
use ngx_http_send_response() in empty_gif
Igor Sysoev <igor@sysoev.ru>
parents:
3516
diff
changeset
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126 return ngx_http_send_response(r, NGX_HTTP_OK, &ngx_http_gif_type, &cv); |
577 | 127 } |
128 | |
129 | |
130 static char * | |
131 ngx_http_empty_gif(ngx_conf_t *cf, ngx_command_t *cmd, void *conf) | |
132 { | |
133 ngx_http_core_loc_conf_t *clcf; | |
134 | |
135 clcf = ngx_http_conf_get_module_loc_conf(cf, ngx_http_core_module); | |
136 clcf->handler = ngx_http_empty_gif_handler; | |
137 | |
138 return NGX_CONF_OK; | |
139 } |