January 19, 2016

Nginx指令介绍

详细信息请查看Nginx 原文档(English[#ref1]_, 淘宝中文版[2])

Proxy_cache相关指令

proxy_cache

prox_cache zone_name | off;

为cache指定一个共享存储区。相同的存储区可以在不同的地方使用。如果设定为off可以关闭从上级配置中继承的cache定义。

共享存储区域”zone_name“是由指令proxy_cache_path定义的。

proxy_cache_path

proxy_cache_path  path [levels=levels] keys_zone=name:size
                    [inactive=time] [max_size=size] [loader_files=number]
                    [loader_sleep=time] [loader_threshold=time];

设定缓存的存储路径和其他一些参数。被缓存的数据都存储在文件中。存储在缓存区的key和文件名是通过被代理的URL的MD5值处理后得到的。参数`levels`用于定义缓存的存放级别的。例如：下面的指令：

proxy_cache_path /data/nginx/cache *levels*=1:2 keys_zone=one:10m;

被缓存的文件在缓存区中是这样存放的:

/data/nginx/cache/c/29/b7f54b2df7773722d382f4809d650*29c*

A cached response is first written to a temporary file, then a file is renamed. Starting from version 0.8.9 temporary files and the cache can be put on different file systems but be aware that in this case a file is copied across two file systems instead of the cheap rename operation. It is thus recommended that for any given location both cache and a directory holding temporary files set by the proxy_temp_path directive are put on the same file system. 缓存的响应首先写入到一个临时文件，然后进行重命名。

In addition, all active keys and information about data are stored in a shared memory zone, whose name and size are configured by the keys_zone parameter. Cached data that are not accessed during the time specified by the inactive parameter get removed from the cache regardless of their freshness. By default, inactive is set to 10 minutes.

The special process “cache manager” monitors the maximum cache size set by the max_size parameter; when this size is exceeded it removes the least recently used data.

A minute after the start the special process “cache loader” is activated that loads information about previously cached data stored on file system into a cache zone. A load is done in iterations. During one iteration no more than loader_files items are loaded (by default, 100). Besides, the duration of one iteration is limited by the loader_threshold parameter (by default, 200 milliseconds). A pause is made between iterations, configured by the loader_sleep parameter (by default, 50 milliseconds).

proxy_cache_bypass

proxy_cache_bypass string ...;

定义在哪些情况下，响应数据不从缓存中取得。当至少有一个字符参数不为空(“”)且不等于”0”，响应就不会从缓存中提取。

proxy_cache_bypass的功能与下面的proxy_no_cache相同。

proxy_no_cache

proxy_no_cache string ...;

与proxy_cache_bypass相同。

proxy_cache_key

proxy_cacke_key $scheme$proxy_host$request_uri;

proxy_cache_valid

proxy_cache_valid 200 302 10m;
proxy_cache_valid 404 1m;
proxy_cache_valid any 1m;

proxy_cache_lock

proxy_cache_lock on | off

proxy_cache_lock_timeout

proxy_cache_lock_timeout 5s

proxy_cache_min_uses

proxy_cache_min_uses 1;

proxy_cache_use_stale

proxy_cache_use_stale error | timeout | invalid_header | updating | http_500
                        | http_502 | http_503 | http_504 | http_404 | off ...;

proxy_cache_methods

proxy_cache_methods GET | HEAD | POST ...;

问题

  • proxy cache的流程是什么样的？
  • proxy_cache, proxy_temp_path, proxy_store三种存储有什么差别？