Ngx_srcache v0.12: new config directives and bug fixes

Hi, all!

I’m happy to announce that ngx_srcache v0.12 has just been released.
You can download the release tarball from the download page below:

http://github.com/agentzh/srcache-nginx-module/downloads

Special thanks go to Andre (shoki) for contributing a lot for this
release :slight_smile:

Here goes the complete change log:

  • now we properly support fetch/store subrequests with internal
    redirection in them. main requests with internal redirection will
    still not be stored into the cache if there is a cache miss. thanks
    Liseen Wan for reporting it.

  • fixed spots that trigger the unused-but-set-variable warning by gcc
    4.6.

  • added srcache_store_skip and srcache_fetch_skip directives to skip
    cache fetching or storing based on variables that are set and not
    empty nor 0. thanks Andre. Examples of using Lua to set $nocache to
    avoid storing URIs that contain /tmp:

set_by_lua $nocache ’
if string.match(ngx.var.request_uri, “/tmp”) then
return “true”
else
return “”
end’;

srcache_store_skip $nocache;

  • added new directive srcache_store_max_size. thanks Andre.

  • made our filter optimization work with nginx HUP by clearing the
    ngx_http_srcache_used flag at nginx pre-config callback. thanks Marcus
    Clyne.

  • now we skip NULL chains in our output filters and also removed the
    SUBREQUEST_IN_MEMORY flag for our srcache_store subrequests because it
    will cause mysterious hanging issues when memcached returns
    CLIENT_ERROR for “get”.

The ngx_srcache module provides a transparent caching layer for
arbitrary nginx locations (like those use an upstream or even serve
static disk files). Usually, the ngx_memc module is used together with
this module to provide a concrete caching storage backend. But
technically, any modules that provide a REST interface can be used as
the fetching and storage subrequests used by ngx_srcache, for example,
ngx_redis2.

For main requests, the srcache_fetch directive works at the end of the
access phase, so the standard access module’s “allow” and “deny”
direcives run before ours, which is usually the desired behavior for
security reasons.

You can find the complete documentation on the project page hosted on
GitHub:

http://github.com/agentzh/srcache-nginx-module

This module has been heavily used in our production environment for
more than a year, as illustrated in the following chart:

http://agentzh.org/misc/slides/perl-lz-apps/index.html#23

Several outside users have also reported success in their production
use.

Also, this module is included and enabled by default in our
ngx_openresty bundle: http://openresty.org

Enjoy!
-agentzh