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From: munnari!csc.anu.oz.au!gih900@UUNET.UU.NET (Geoff Huston)
Newsgroups: news.software.anu-news
Subject: Re: Reading news in a thunderstorm is hazardous.
Message-ID: <8908011544.AA20257@uunet.uu.net>
Date: 1 Aug 89 15:20:25 GMT
Sender: ANU-NEWS Discussion <ANU-NEWS@NDSUVM1.BITNET>
Reply-To: Geoff Huston <munnari!csc.anu.oz.au!gih900@UUNET.UU.NET>
Lines: 47

Re -- Reading news in a thunderstorm is hazardous.
     
>> In article <430@decus.com.au>, sutton@decus.com.au (Colin Sutton) writes:
>>> I am always on teneterhooks reading news from home via dial-up modem,
>>> because if the line goes down, all the items I read are now unread again
>>> ...  Couldn't the NEWSRC file be updated as the news is read? ... I assume
>>> that the file would be kept open, so it wouldn't take long to update. And
>>> news would be quicker to exit too - just close the file.
>
>Actually, the problem seems to be one of insufficient paranoia, and the
>approach you suggest is unfortunately exactly the one which would most
>exacerbate the problem, if it weren't already implemented.  It seems
>that the file is already being kept open - and when something unexpected
>happens the file suffers the consequences.  On our DEC-2060, using NEWS
>(5.2(1213)) and NNTP to get netnews from a Pyramid, if the Pyramid goes
>away unexpectedly, so _may_ your NEWSRC file.  It happens fairly often.
>Therefore, I recommend to our users that they keep a backup copy, which
>is not exactly easy given the filename (^V^?^V[NEWS^V].NEWSRC).
>
>You _really_ want to open the file for read, slurp it up, and close it
>immediately.
     
This is exaclty what NEWS already does - NEWS opens the NEWSRC file and reads
it in - then closes it.
     
>  Then, when the file is safe, you may parse the text in the
>buffer at leisure.  Engage the user in their chosen dialogue and maintain
>the state in the buffer.  When the time comes, open the file for write,
>write it all, and close it immediately.  Open files are very vulnerable;
>closed files are much more likely to survive any odd occurrence.
     
>If you want a command to update the NEWSRC file at the user's whim, then
>that should be reasonably easy to add, and its cost would be obvious to
>the user when they use it, so they could make a rational decision about
>how often to force an update.  It is almost always best to do as little as
>possible without specific direction to do so, if for no other reason than
>to obey The Law of Least Surprise.
     
DIR/RESET does exactly this - it's a case of the wrong command name here!
     
NEWSRC was set up as a text file - not an indexed file - this is both good and
bad - the file contents may be changed using a text editor - BUT updates on the
fly are a complete dump of the NEWS variables into the file as text. It's all a
case of swings and roundabouts.
     
Geoff Huston
gih900@csc.anu.oz.au