Re: Synchronization Problem

[norm]

Ken Hornstein <kenh@pobox.com> writes:
>>fetchmail runs off a deamon and deposits emails which are in fine nmh format
>>but do not have a numeric names. So I run this script:
>>[...]
>>But after the scan is complete and before I do the rmm, the script might
>>have put a new message in +inbox, which rmm would remove.
>
>There aren't _wonderful_ solutions, because this is a higher-level problem;
>other programs can change the state of your inbox between commands.
>Unless you want to do something like Kevin Cosgrove suggested, this is
>fundamental to your design.  You could do some higher-level locking
>where you prevent your script from running while you read your inbox.

I solved my particular problem by realizing that inc works fine when I point
it to a file containing just one message and no message dividers.

But it does illustrate what I think might be a more fundamental problem with
nmh: there is no way for that a user-written script can participate in nmh's
internal locking mechanism -- or if there is I don't recall where it is
documented. So I wonder if there is some way that this problem could be
resolved. Would it be very hard to implement a couple of new nmh commands?
Maybe something like this:

     nmhlock  [ -timeout milliseconds] (returns a token in stdout)
     nmhunlock token

    Norman Shapiro