Date: Mon, 23 Aug 1999 23:27:27 -0400 From: Christopher Masto <chris@netmonger.net> To: Chuck Robey <chuckr@picnic.mat.net> Cc: Garance A Drosihn <drosih@rpi.edu>, "Daniel C. Sobral" <dcs@newsguy.com>, Greg Lehey <grog@lemis.com>, Poul-Henning Kamp <phk@critter.freebsd.dk>, Matthew Dillon <dillon@apollo.backplane.com>, FreeBSD Hackers <hackers@FreeBSD.ORG>, FreeBSD Committers <cvs-committers@FreeBSD.ORG>, Garrett Wollman <wollman@khavrinen.lcs.mit.edu> Subject: Re: Mandatory locking? Message-ID: <19990823232726.B16133@netmonger.net> In-Reply-To: <Pine.BSF.4.10.9908232313540.49952-100000@picnic.mat.net>; from Chuck Robey on Mon, Aug 23, 1999 at 11:16:21PM -0400 References: <19990823231130.A16133@netmonger.net> <Pine.BSF.4.10.9908232313540.49952-100000@picnic.mat.net>
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On Mon, Aug 23, 1999 at 11:16:21PM -0400, Chuck Robey wrote: > On Mon, 23 Aug 1999, Christopher Masto wrote: > > > Bleah.. I can't count the number of times I've seen idiotic code like: > > > > open file > > read data > > close file > > open file for write > > write data > > close file > > > > Mandatory locking of the type above doesn't force such a thing to work. > > What has that code you show above got to do with mandatory locking? > You completely missed the explicit locking calls that you have to make, > to get and release the locks. If you don't make the call, and you have > madatory locking, then your process will sleep until someone else > releases the lock; Exactly. You said that mandatory locking means that user A's correct use of locking means that user B doesn't have to be careful. That's not the case, since A can step in between B's read and write. A's mandatory lock doesn't help. I don't see the use for it. -- Christopher Masto Senior Network Monkey NetMonger Communications chris@netmonger.net info@netmonger.net http://www.netmonger.net Free yourself, free your machine, free the daemon -- http://www.freebsd.org/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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