robust locking

[Conor P. Cahill]

In article <2320 at cirrusl.UUCP> dhesi%cirrusl at oliveb.ATC.olivetti.com (Rahul Dhesi) writes:
>A very simple mechanism can be used to ensure that such race conditions
>don't occur. Create a lock file that contains both process id and host
>name.  If a second process wants to create the same lock, it checks any
>existing lock file.  If the lock file exists, and the host name in it
>is that of the current host, then the process id in it can be tested to
>see if it is that of an existing process (and if not, that process
>crashed and the lock file can be superseded).  But if the host name in
>the lock file is that of a different host, we refuse to supersede the
>lock.

But if you allow both processes to run on different hosts, you need to 
modify the other parts of rn that deal with the .newsrc and other related
status/setup files.  You will run into real problems when two processes 
try to write out different .newsrc files.


-- 
Conor P. Cahill            (703)430-9247        Virtual Technologies, Inc.,
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