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From: Achim Gratz <Stromeko@nexgo.de>
Subject: Re: [TEST] sqlite3-3.7.17-1 (Cygwin 1.7.19 locking feature)
Date: Thu, 06 Jun 2013 20:17:12 +0200
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Message-ID: <87ppvzdryv.fsf@Rainer.invalid>
References: <51ACF886.10301@etr-usa.com> <51AD3BB4.2010601@acm.org>	<20130604084128.GB19572@calimero.vinschen.de>	<20130604093749.GA32667@calimero.vinschen.de>	<51AF9A32.2030706@etr-usa.com>	<20130606172218.GD13320@calimero.vinschen.de>
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Corinna Vinschen writes:
> In theory this scenario could be worked around in Cygwin by bookkeeping
> the present locks, plus a piece of code which unlocks all existing locks
> in the given range when a lock or unlock request is coming in.  However,
> the really dismal fact is, that an unlock before a lock would never be
> atomic.  If the F_SETLK request unlocks an existing lock and then
> another process gets a lock in the requested range, the first process
> ends up with a failed fcntl call and no lock at all.

Thanks for the explanation, I'm beginning to see what the backoff / retry
code in SQLite on WIndows is supposed to be doing (hopefully).


Regards,
Achim.
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