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000136_icon-group-sender _Fri Jun 14 08:53:07 1996.msg
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Received: by cheltenham.cs.arizona.edu; Fri, 14 Jun 1996 08:18:43 MST
Date: Fri, 14 Jun 1996 08:53:07 +0200
From: karczma@calvin.info.unicaen.fr (Jerzy Karczmarczuk)
Message-Id: <9606140653.AA00140@canardo.unicaen.fr>
To: icon-group@cs.arizona.edu
Subject: Locking files
X-Sun-Charset: US-ASCII
Errors-To: icon-group-errors@cs.arizona.edu
Status: O
David Harrison writes:
> I am using Icon 9.1 on an SGI IRIX 5.3 machine. Is there support for
> locking files? I am using Icon to process CGI requests from a web
> server. Since multiple people might access the programs at once,
> I would like to lock the file processing phases of these programs.
> I didn't see anything right off hand in the documentation.
>
> David Harrison, Molecular Simulations
I am not sure whether FCNTL is supported by Icon on all Unix
platforms, and so the selective locks you might program by hand,
but don't forget that there is a cheap way of locking something
globally used for ages: the *creation* of a special "lock" file
just before entering the critical section (if it is absent,
otherwise sleep/wait), and the destruction after.
This has nothing to do in principle with Icon. But it suggests
another question. Does Icon support DBM or some other not-so-low
level of database management? I found already several times that the
explosion of web programs and the 100-fold increase in the number of
people who do something in the domain without being extremely
technically oriented gurus, increased the number of not very
secure programs, because the nice, user-friendly and high-level
languages lack some tools adapted to the non-cooperative
environments.
And worried people will still use Perl...
Jerzy Karczmarczuk
Dept.of Comp. Sci., University of Caen, Normandy, France.