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Date: Wed, 22 Sep 2004 11:52:41 +0200
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To: Sara Golemon <pollita@php.net>
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Subject: Re: [PHP-DEV] realpath() caching
From: cschneid@cschneid.com (Christian Schneider)

Sara Golemon wrote:
>>realpath_cache_ttl - Time to live for cache entry (default 120 seconds; if
>>set to 0 then doesn't refresh).
>>
> Ah, didn't grok the TTL at first glance....  that fairly well negates the
> need for an explicit flush.... If the FS layout needs to change all one
> would have to do is turn down the TTL, make the change, and turn it back up
> after the cache is sure to be cleared...

Hmm.. if I understand correctly then one can only turn it down to 1 
second as 0 means unlimited. So if an application changes the tree it 
would have to sleep(1) for it to happen.

I'd strongly suggest that we have an explicit flush option. And no, I 
don't think restarting the server is an opton as this can't be done from 
inside an application.

BTW: This needs to be well documented as running into caching problems 
can cause a very annoying debugging sessions due to the Heisenbug 
nature. Happened to more than one person I know with filesize() with 
missing clearstatcache() calls. One of PHP's main feature is programmer 
efficiency so we should be careful to add optimizations which make 
things harder for programmers.

- Chris