Looking for general advice on complex program
cs at zip.com.au
Fri Jul 15 18:37:41 EDT 2011
On 15Jul2011 16:03, Billy Mays <81282ed9a88799d21e77957df2d84bd6514d9af6 at myhashismyemail.com> wrote:
| I remember reading that file locking doesn't work on network mounted
| drives (specifically nfs mounts), but you might be able to simply
| create a 'lock' (mydoc.xml.lock or the like) file for the XML doc in
| question. If that file exists you could either hang or silently
| give up. Not sure if that helps.
There are two approaches to this. Plain old make-a-file won't work - it
is racy (and as mentioned, you can't rely on the various lock
You can create a file while your umask is 0777; it will be non-writable
immediately (no chmod required), preventing another attempt to make it.
My personal habit is to make a directory for the lock; mkdir
also can't happen twice to the same name, you don't need to fiddle you
umask (racy and annoying, and problematic if you're using multiple
threads), _and_ you can put meta info inside it, like pid files etc.
Cameron Simpson <cs at zip.com.au> DoD#743
I had a wierd dream with Ken Thompson in it once.
- George Politis <george at research.canon.com.au>
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