Re: Checking file modification dates in NSDocument
Re: Checking file modification dates in NSDocument
- Subject: Re: Checking file modification dates in NSDocument
- From: Sanford Selznick <email@hidden>
- Date: Fri, 28 Jul 2006 13:01:22 -0700
At 11:40 AM -0700 7/28/06, Jordan Krushen wrote:
PS - I've read TN2037 and don't want to implement file locking.
Then you're aware that all of the other work you're doing is
ultimately for nothing, due to the inherent race condition between
when you check for changes and when you commit the new file? If you
don't use locks, then this code will quite possibly still destroy data
under heavy use. You say you don't want to use locks, but you're
writing code to ultimately do the same thing -- with the difference
being that locks will prevent corruption, while your code will not.
You are right, of course. File Locking is the right solution.
Unfortunately it's a royal pain the butt. And every app has to do it.
So, why isn't this built into Cocoa? TN2037 says exclusive locks are
automatic in the framework, but I can clearly open/write the same
document from two instances of my Cocoa app:
"By accessing files through the application frameworks (Carbon,
Cocoa, Java), in versions of the OS supporting the advisory locks
feature in frameworks, this will be provided automatically if you use
the framework's file access methods."
A bold statement. But it doesn't appear to be true. Cocoa is
clearly tracking my document... I can rename it in the Finder and
watch MyDocument's window update. So why isn't the file locked for
writing by others?
So what's the solution? Stop using NSDocument?
Or perhaps: how does one patch NSDocument to do File Locking?
Or am I using the wrong Cocoa file access methods?
Thank you,
Sanford
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