Mercurial > hg > nginx-site
comparison xml/en/docs/http/ngx_http_proxy_module.xml @ 1910:41cf2c2d8c5c
Cache: support for stale-while-revalidate and stale-if-error.
author | Yaroslav Zhuravlev <yar@nginx.com> |
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date | Wed, 15 Feb 2017 23:17:00 +0300 |
parents | 399d0e188195 |
children | ec4af97e4403 |
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1909:399d0e188195 | 1910:41cf2c2d8c5c |
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8 <!DOCTYPE module SYSTEM "../../../../dtd/module.dtd"> | 8 <!DOCTYPE module SYSTEM "../../../../dtd/module.dtd"> |
9 | 9 |
10 <module name="Module ngx_http_proxy_module" | 10 <module name="Module ngx_http_proxy_module" |
11 link="/en/docs/http/ngx_http_proxy_module.html" | 11 link="/en/docs/http/ngx_http_proxy_module.html" |
12 lang="en" | 12 lang="en" |
13 rev="55"> | 13 rev="56"> |
14 | 14 |
15 <section id="summary"> | 15 <section id="summary"> |
16 | 16 |
17 <para> | 17 <para> |
18 The <literal>ngx_http_proxy_module</literal> module allows passing | 18 The <literal>ngx_http_proxy_module</literal> module allows passing |
638 <context>server</context> | 638 <context>server</context> |
639 <context>location</context> | 639 <context>location</context> |
640 | 640 |
641 <para> | 641 <para> |
642 Determines in which cases a stale cached response can be used | 642 Determines in which cases a stale cached response can be used |
643 when an error occurs during communication with the proxied server. | 643 during communication with the proxied server. |
644 The directive’s parameters match the parameters of the | 644 The directive’s parameters match the parameters of the |
645 <link id="proxy_next_upstream"/> directive. | 645 <link id="proxy_next_upstream"/> directive. |
646 </para> | 646 </para> |
647 | 647 |
648 <para> | 648 <para> |
649 The <literal>error</literal> parameter also permits | 649 The <literal>error</literal> parameter also permits |
650 using a stale cached response if a proxied server to process a request | 650 using a stale cached response if a proxied server to process a request |
651 cannot be selected. | 651 cannot be selected. |
652 The same behavior can be enabled with the | |
653 “<link url="https://tools.ietf.org/html/rfc5861#section-4">stale-if-error</link>” | |
654 extension of the <header>Cache-Control</header> response header field (1.11.10) | |
655 for a specified number of seconds after the response became stale, | |
656 however, this has lower priority than using the directive parameter. | |
652 </para> | 657 </para> |
653 | 658 |
654 <para id="proxy_cache_use_stale_updating"> | 659 <para id="proxy_cache_use_stale_updating"> |
655 Additionally, the <literal>updating</literal> parameter permits | 660 Additionally, the <literal>updating</literal> parameter permits |
656 using a stale cached response if it is currently being updated. | 661 using a stale cached response if it is currently being updated. |
657 This allows minimizing the number of accesses to proxied servers | 662 This allows minimizing the number of accesses to proxied servers |
658 when updating cached data. | 663 when updating cached data. |
664 The same behavior can be enabled with the | |
665 “<link url="https://tools.ietf.org/html/rfc5861#section-3">stale-while-revalidate</link>” | |
666 extension of the <header>Cache-Control</header> response header field (1.11.10) | |
667 for a specified number of seconds after the response became stale, | |
668 however, this has lower priority than using the directive parameter. | |
659 </para> | 669 </para> |
660 | 670 |
661 <para> | 671 <para> |
662 To minimize the number of accesses to proxied servers when | 672 To minimize the number of accesses to proxied servers when |
663 populating a new cache element, the <link id="proxy_cache_lock"/> | 673 populating a new cache element, the <link id="proxy_cache_lock"/> |