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Date:	13 Feb 2001 14:17:56 -0500
Message-ID:	<20010213191756.15822.qmail@lizard.curl.com>
From:	jik-cygwin AT curl DOT com
To:	lhall AT rfk DOT com
CC:	cygwin AT cygwin DOT com
In-reply-to:	<4.3.1.2.20010213140154.019d99c8@pop.ma.ultranet.com>
	(lhall AT rfk DOT com)
Subject:	Re: Optimizing away "ReadFile" calls when Make calls stat()
References:	<4 DOT 3 DOT 1 DOT 2 DOT 20010213134821 DOT 019a7130 AT pop DOT ma DOT ultranet DOT com>
	<4 DOT 3 DOT 1 DOT 2 DOT 20010213134821 DOT 019a7130 AT pop DOT ma DOT ultranet DOT com> <4 DOT 3 DOT 1 DOT 2 DOT 20010213140154 DOT 019d99c8 AT pop DOT ma DOT ultranet DOT com>

>  Date: Tue, 13 Feb 2001 14:08:58 -0500
>  From: "Larry Hall (RFK Partners, Inc)" <lhall AT rfk DOT com>
>  
>  >1) The cache would have to be automatically invalidated whenever the
>  >    file is changed, and you'd thus need to check if a file has changed
>  >    before using the cache, and those checks would themselves take
>  >    time.
>  
>  I'd submit that while this may be true in general, it shouldn't be in the
>  case of symbolic links and executables.  These attributes don't really change
>  or, if they do, they change in a very defined way which should make it 
>  possible to track.

Yikes, I don't agree with that at all.

Non-deterministic behavior is *much* worse than slow behavior.  It
would be *impossible* for Cygwin to track every single change to
symbolic links and/or executable files, since people can modify such
files without going through Cygwin at all (e.g., modifying them
directly with a Windows app, or modifying such a file on a SAMBA mount
through Linux).

Since it's impossible for Cygwin to know when such files are changed
out from under it, it *must* check them, or at least check if they
have been changed, each time they are accessed.

  jik

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