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Re: request-route
From: kragen () dnaco net (Kragen Sitaker)
Date: Wed, 30 Jul 1997 23:05:38 -0400


On Tue, 29 Jul 1997, John Macdonald wrote:
Eric Bennett wrote :
|| On Tue, 29 Jul 1997, Zoltan Hidvegi wrote:
|| > lock files in a world-writable directory from a bourne-shell script.
||
|| I have done this by creating directories instead of files: only one mkdir
|| will complete.

Nope, you;ve got it backwards.  To begin, the same basic problem
applies to both.  If an operation succeeds, but the
acknowledgement gets lost on the network, then the time-out
cause a retry which will fail because the target item exists.

I believe that most implementations of NFS maintain a cache of the most
recent few non-idempotent operations (mkdir, rm, rmdir, etc.) and their
results; if the request is retried, the result is resent.  Can someone who
has read the code confirm or deny this?

Kragen



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