owens-christopher@YALE.ARPA.UUCP (09/24/87)
I am toying with the idea of writing file locking code to use the
Apollo system calls. But I want to be philosophically consistent with
what GNU-emacs does now, and I don't want to do it at all if someone
else has already done it. So....
1) Why does GNU-emacs manage its own file-locking instead of using
system built-ins?
2) Where else besides the obvious filelock.c do I need to hook in to
the existing code?
3) Has anybody else already done this?
thanks,
/c
ARPA: Owens-Christopher@cs.yale.edu
UUCP: {decvax,linus,seismo}!yale!Owens-Christopher
BITNET: Owens@yalecsjr@pebbles.bbn.COM (John Robinson) (05/16/88)
The code in filelock.c is nice as far as it goes, but it doesn't really work out so well in an NFS environment. You can imagine the problems: should there be one centralized lock directory across all file servers? this hardly works if there are like-named directories on different machines, and puts one machine at a severe disadvantage every time an emacs user modifies a buffer. At the other extreme is to define PATH_LOCK to be "/tmp/" which only protects you against yourself or other users of your particular machine. I don't really like either of these very much. So what I would like to know is (1) is it possible to use flock() on systems that have it to provide at least some of the interlocking? and/or (2) has anyone come up with a working scheme in NFS (find out what server has the file you are modifying and go to the PATH_LOCK directory on that server)? Other suggestions welcome as well. /jr jr@bbn.com or bbn!jr