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Date: Wed, 17 Aug 2005 16:11:01 -0400
From: Brian Akins <brian.akins@turner.com>
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To: dev@httpd.apache.org
Subject: Re: [PATCH] mod_disk_cache deterministic tempfiles
References: <BF290A20.1AFF%Brian.Akins@turner.com> <430398AA.2040609@sharp.fm>
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Graham Leggett wrote:

> This is very cool. On my list of things to do was to handle something 
> similar for serving from the cache as well - again to avoid a thundering 
> herd against backend servers while a file is being cached.


I have the thought that we could also serve files that have "recently 
expired" (recent being configurable) if the object was being cached. 
Psudocode:

if(expired < (now - recent)) {
	if(stat(tmpfile) {
		if(mtime_is_resonable) {
			serve_old_file;	
		} else {
			unlimk(tempfile)
		}
	}
}

This would also allow only one request through to "refresh" the object 
and protect against a "hung" worker (bad backend server, database, whatever)


-- 
Brian Akins
Lead Systems Engineer
CNN Internet Technologies