Re: MAIL_USE_FLOCK and Debian.

[Richard Stallman]

    If I understand the situation correctly, I'm not sure this is anything
    that actually can be decided automatically.  The problem is that in
    the final analysis, the policies with respect to locking may come down
    to a local administrative decision.

I think that is even more reason to control the decision at run time.
Binaries are often moved from machine to machine, on a given platform.
People will, for instance, install the Debian Emacs package on various
Debian systems, some of which use liblockfile and some of which don't.

A run-time configuration option is much more powerful and convenient.

So the code should compile support for using liblockfile whenever
liblockfile is defined, and should compile the other method as well
(whichever other method is used now), and the final choice would be
controlled by an environment variable or a file installed with Emacs.

It would be ok to extend this idea of run-time choice to the question
of whether to use flock.  The idea would be that there are three
possible methods, and the code for each one would be compiled whenever
the platform permits that, and the final choice would be made at run
time.

The variable MAIL_USE_FLOCK would then help control the default
setting for the run-time choice.


Do you agree?  Would you like to implement it?