At 8:15 am +0100 18/2/02, Bertrand Delacretaz wrote:
Thanks for your reply, Bertrand,
>On Saturday 16 February 2002 14:27, Jeremy Quinn wrote:
>>. . .
>> I suspect I ought to be Serialising into a temporary file and
>> replacing the original only after everything has worked.
>
>Makes sense, AFAIK renaming a file is an atomic operation on all
>current OSes.
That's good to hear ...
>>. . .
>> How do I block the process of a second simultaneous request?
>> Do I 'syncronize' the temporary file?
>
>If you want to do this in memory (which makes sense in your case I
>think), you have to have all instances of your component synchronize on
>a shared java object that maps to the absolute filename of the
>file you're writing.
>
>One problem in this case is making sure the lock on your file is
>released if the file writing operation fails, probably using a lock
>validity timeout .
>
>In a monolithic program you'd create a Singleton component (a static
>single-instance object) to handle such locks. I suspect such mechanisms
>already exist in Avalon, but I'm not familiar enough with it to tell
>you where to look. Maybe some Avalon guru can help you here?
Thanks for your suggestions.
While I am working out how to do this the right way, I'll fix the
Transformer so that it writes to a temporary file as above, and if another
person attempts to simultaneously overwrite, I can just throw an Excpetion
and have them try again later. I would like to work out how to do this
properly though ;)
Thanks
regards Jeremy
--
___________________________________________________________________
Jeremy Quinn Karma Divers
webSpace Design
HyperMedia Research Centre
<mailto:[EMAIL PROTECTED]> <http://www.media.demon.co.uk>
<phone:+44.[0].20.7737.6831> <pager:[EMAIL PROTECTED]>
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