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Date: Tue, 4 Jun 2013 10:48:15 +0200
From: Corinna Vinschen <corinna-cygwin AT cygwin DOT com>
To: cygwin AT cygwin DOT com
Subject: Re: sqlite3: bug with monotone
Message-ID: <20130604084815.GD19572@calimero.vinschen.de>
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References: <51A6B6EB DOT 6050309 AT users DOT sourceforge DOT net> <loom DOT 20130530T122354-144 AT post DOT gmane DOT org> <51A7862F DOT 1070507 AT etr-usa DOT com> <51A7D47E DOT 3050502 AT users DOT sourceforge DOT net> <51A7F547 DOT 6020509 AT etr-usa DOT com> <20130531092228 DOT GB30659 AT calimero DOT vinschen DOT de> <51A900EF DOT 2020606 AT etr-usa DOT com> <20130601105741 DOT GC30659 AT calimero DOT vinschen DOT de> <20130602103125 DOT GE13934 AT calimero DOT vinschen DOT de> <51ACD415 DOT 2090709 AT etr-usa DOT com>
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User-Agent: Mutt/1.5.21 (2010-09-15)

On Jun  3 11:36, Warren Young wrote:
> On 6/2/2013 04:31, Corinna Vinschen wrote:
> >I dropped the F_MDLCK idea. Instead I implemented a specific fcntl code
> >to switch to mandatory locking on a file descriptor:
> >
> >   fcntl (fd, F_LCK_MANDATORY, 1);
> 
> Could you add an O_MAND open(2) option as well to turn on the same
> feature?  This will avoid a race condition.

If you call F_LCK_MANDATORY right after open in the opening routine,
there won't be (much of) a race.  I know what you mean (it's the
O_CLOEXEC dilemma) but is it really that important in terms of locking?

> As I see it, the test will proceed in several stages:
> 
> 0. I patch SQLite and run it against both .18 and your snapshot, and
> strace it to verify that fcntl(fd, 0x99, 1) is called and returns 0
> with the snapshot and returns -1 with errno == EINVAL for .18.  Both
> count as "success" so we don't have to require .19.
> 
> 1. I upload it, and Achim and Yaakov try it and see if this new
> build satisfies their use cases.

Well, we will have more than one round of testing, apparently...(*)


Corinna


(*) http://cygwin.com/ml/cygwin/2013-06/msg00042.html

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Maintainer                 cygwin AT cygwin DOT com
Red Hat

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