If refresh_pattern only extends expiration, how to force time-to-live in Squid code?

I've tried to set an exact time-to-live (override origin cache
control) in Squid (2.4 STABLE6) configuration by refresh_pattern,
e.g.:

refresh_pattern   30_minutes_cache_control_url   15   0%   15
override-expire   ignore-max-age

Observed: URL is matched (in log), but objects still cached for 30
minutes, rather than for 15 minutes, as hoped.

If indeed refresh_pattern only extends expiration, I would like to
develop a feature that enforces an exact time-to-live (per URL) in my
local branch of Squid code.

What would be the most reasonable way to do this? How can I force
objects to expire from cache after a given time?

Thanks.
Received on Thu Aug 27 2009 - 02:21:10 MDT