Mutual exclusion

Mutual exclusion

[chuckw]

Hello All,
	What are the different types of Mutual exclusion primitives available
in linux?  I know there is the pthread mutex and semaphores.  Is there
anything else?

Thanks Much,
Chuck

Re: Mutual exclusion

[Steven Smith]

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> 	What are the different types of Mutual exclusion primitives available
> in linux?  I know there is the pthread mutex and semaphores.  Is there
> anything else?
Off of the top of my head:

1) pthreads spinlocks
2) pthreads barriers
3) pthreads conditional variables
4) pthreads rwlocks
5) SysV semaphore sets
6) SysV message queues
7) fcntl file locks
8) flock file locks
9) You could probably do something with signals as well, if you're careful
10) Or with a load of pipes and suitable ingenuity
11) link() and the dnotify API, if you're feeling somewhat silly
12) flockfile()

These require varying degrees of cleverness to use, and the best one
(as always) depends on what you're using it for. There are probably
more if you look hard enough, as well.

Unless you have somewhat unusual needs, it's probably easiest to
stick to pthreads mutexs and semaphores.

Steven Smith,
sos22@cam.ac.uk.

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Detecting file changes?

[Christopher Quinn]

Hello list.

Is there a way other than polling to detect when a file's contents change?
I was hoping something like select(2).
Any ideas?

Thanks,
Chris

Re: Detecting file changes?

[Billy O'Connor]

   >From billy  Mon Jun 10 16:51:33 2002
   Date:	Mon, 10 Jun 2002 22:47:21 +0100
   From: Christopher Quinn <cq@htec.demon.co.uk>
   X-Accept-Language: en-us, en
   Sender: linux-c-programming-owner@vger.kernel.org
   X-Mailing-List:	linux-c-programming@vger.kernel.org

   Hello list.

   Is there a way other than polling to detect when a file's contents change?
   I was hoping something like select(2).
   Any ideas?

   Thanks,
   Chris

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Check out sgi_fam.  This uses select to monitor file accesses.  One
source would be:

http://mirror.hiwaay.net/redhat/redhat/redhat-7.3-en/os/i386/SRPMS/fam-2.6.7-6.src.rpm

--
Billy O'Connor