[squid-users] TCP_REFRESH_UNMODIFIED instead of TCP_IMS_HIT? "Revalidation failed"

Hi all!

First, I am pretty new to proxies, so please bare with me if I'm doing
something completely wrong. What I want to do:

I have a VPN tunnel between two sides and a server serving java webstart
jars on one side and I want to cache these on the other side. Because
the jars should always be the same as on the original server, I want
them to be stale all the time, so that squid checks the last modified
date and returns the jar from cache only if the dates are equal. So far
so good.

What I have done:

I used the standard squid (3.1.16) config on my gentoo system and put a
refresh_pattern instead of the default refresh_patterns (I only want to
cache jars):

refresh_pattern -i \.(jar)\??(.*?)$ 0 0% 99999 reload-into-ims refresh-ims

and set the following options:

coredump_dir /squid_cache
cache_replacement_policy heap LFUDA
cache_dir ufs /squid_cache 2000 16 256

maximum_object_size 256 MB

Testing with a browser: The first time I request a jar I get X-Cache:
MISS and X-Cache-Lookup: MISS which is perfectly fine but after that it
gets interesting:

HTTP/1.0 200 OK
Date: Tue, 29 Nov 2011 13:37:59 GMT
Content-Type: application/java-archive
Content-Length: 66245
Last-Modified: Tue, 29 Nov 2011 12:21:04 GMT
Server: Jetty(6.1.16)
Warning: 110 squid/3.1.16 "Response is stale", 111 squid/3.1.16
"Revalidation failed"
X-Cache: HIT from proxytest
X-Cache-Lookup: HIT from proxytest:3128
Via: 1.0 proxytest (squid/3.1.16)
Connection: keep-alive

Why do I get a "Revalidation failed"? I took a look at the headers
between proxy and original server -> the original server sends a HTTP
1.1 304. So the revalidation should succeed, right? If I take a look at
the squid log, it says:

1322573879.858 8 192.168.100.215 TCP_REFRESH_UNMODIFIED/200 66658
GET http://bla.bla.bla:8080/afdc3604/lib/commons-logging-1.1.1.jar -
DIRECT/192.168.100.199 application/java-archive

So I get the jar file not from cache, but DIRECT from the original
server. Why? The file is unmodified. Shouldn't I get a TCP_IMS_HIT?

If I change the refresh_pattern so that the file is not stale at any
time I get it from cache just fine, so cache is working basically. But
the revalidation just doesn't work and I have no idea why?

Any hints?

TIA,
David
Received on Tue Nov 29 2011 - 14:20:05 MST