Re: apt experimental breaks w/ webcaching (was Re: apt 0.6 in experimental)
On Fri, Jan 02, 2004 at 05:37:31PM +0000, Colin Watson wrote:
> On Fri, Jan 02, 2004 at 09:11:31AM -0800, Matt Zimmerman wrote:
> > Since Release and Packages/Sources are generated at close to the same
> > time, they should always be about the same age, and the heuristics
> > should apply to them equally.
> They will be the same age on the *server*, but not necessarily in the
> cache, as my example quoted up at the top of this message shows. The
> cachedness or otherwise of an entity is very likely to be an input to the
> caching heuristics.
I don't know what other caches do, but Squid's expiration time heuristics
are based on the modification time of the file:
# FRESH if expires < now, else STALE
# STALE if age > max
# FRESH if lm-factor < percent, else STALE
# FRESH if age < min
# else STALE
expires represents an explicit expiration time, age is the age of the object
in the cache, and lm-factor is based on the last-modified time on the file.
So the age of the object in the cache only comes into play with the max and
min parameters, not when estimating an expiration time when none is
It would be great if the mirrors would supply explicit Expires headers,
since they know when they will be next synched.