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From Niklas Edmundsson <>
Subject [PATCH] mod_cache 304 on HEAD (bug 41230)
Date Fri, 13 Apr 2007 15:31:12 GMT
On Wed, 11 Apr 2007, Niklas Edmundsson wrote:

> Looking a bit further, I think that something like this would actually be 
> enough:
<snip, included as an attachment>

I have now tested this patch, and it seems to solve the problem. This 
is on httpd-2.2.4 + patch for PR41475 + our mod_disk_cache patches.

Without the patch a HEAD on a cached expired object that isn't 
modified will unconditionally return 304 and furthermore cause the 
cached object to be deleted. We believe that this is the explanation 
to why it has been so hard to track down this bug - it only bites one 
user and that user usually has no clue on what happens, and even if we 
try to reproduce it immediately afterwards it won't trigger.

With the patch stuff works like expected:
- A HEAD on a cached expired object that isn't modified will update
   the cache header and return the proper return code, it follows the
   same code path as other requests on expired unmodified objects.
- A HEAD on a cached expired object that IS modified will remove the
   object from cache and then decline the opportunity to cache the

I request that this is reviewed, commited and proposed for backport to 
httpd 2.2.5.

  Niklas Edmundsson, Admin @ {acc,hpc2n}      |
  "The pain is bad enough. Don't go poetic on me." - Madeline
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