Re: Notification of file system modification arrives too early?
Re: Notification of file system modification arrives too early?
- Subject: Re: Notification of file system modification arrives too early?
- From: Antonio Nunes <email@hidden>
- Date: Sun, 30 May 2010 23:43:19 +0100
On 30 May 2010, at 17:51, Jens Alfke wrote:
>> When a change occurs, I attempt to open the file using the FS API specifying exclusive read + exclusive write access. If it fails, it's likely because some other process still has the file open. I delay a half second or so and try again.
>
> That sounds like a good approach, but it’s not 100% reliable. If the creating process opened the file without requesting an exclusive lock, then your open call will succeed even though the file is still open.
>
> Unfortunately you probably can’t do any better than that, since there’s no cheap way to find out if another process has the file open.
Thanks guys, that makes it sound like my previously mentioned solution/work-around of trying to create a PDFDocument from the URL is the safest solution. The attempt will fail until the file has been fully written, and I only need to read the data, not write to it. Also, as far as I can tell, reading a PDFDocument with initWithURL: (and immediately discarding it if it succeeds) is a fairly cheap operation.
António
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Forgiveness is not an occasional act;
it is a permanent attitude.
--Martin Luther King, Jr
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