Midgard is quite a huge framework, and so caching is needed to keep things efficient. To that effect, MidCOM 2.4 in 2005 added a major feature of caching generated pages until they needed reconstructing.

However, with the 2005 technology the caching system proved to be troublesome: Berkeley DB corruption, faulty invalidation mechanisms and other problems. When we started working on MidCOM 2.5 we decided to remove MidCOM’s own content caching infrastructure in favor of using a Squid reverse proxy.

Squid is quite a nice piece of software, but it also mean adding quite a big dependency on top of our software stack, and so lots of smaller sites ran without it.

To remedy that problem we have now revived the content cache with more reliable storage back-ends and invalidation mechanisms. The new system follows some ESI conventions and produces quite nice performance gains.

It is already available in both MidCOM trunk and in latest 2.8 beta packages. To start using it, simply make the following configuration change:

$GLOBALS['midcom_config_local']['cache_module_content_uncached'] = false;

Thanks to Tero Heikkinen for pushing this through!

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