Path: utzoo!attcan!uunet!husc6!bbn!mailrus!b-tech!zeeff
From: zeeff@b-tech.ann-arbor.mi.us (Jon Zeeff)
Newsgroups: comp.unix.xenix
Subject: Re: Shared Memory Problem
Message-ID: <4918@b-tech.ann-arbor.mi.us>
Date: 5 Nov 88 17:13:44 GMT
References: <3246@ucdavis.ucdavis.edu>
Reply-To: zeeff@b-tech.ann-arbor.mi.us (Jon Zeeff)
Organization: Branch Technology Ann Arbor, MI
Lines: 23

In article <3246@ucdavis.ucdavis.edu> tuck@iris.ucdavis.edu (Devon Tuck) writes:
>in FORTRAN, to our Xenix 386/20 system.  It is necessary for at least 3
>different programs to have access to an input buffer which is constantly
>being filled. 

>The closest solution I have found, is to create a host subroutine which
>passes the buffer array of a program into  shared memory, loads it with the
>new information, and then returns it.  The problem with this is, the loop
>which checks for this new information will most probably be an infinite
>loop,

If I understand your situation correctly, you want several programs to 
wait on an update of a shared memory segment without sitting in an 
polling loop.  One way to do this would be to create a fifo (with 
mknod(1)) for each process and write a byte to each of them when you 
update the segment.  The other processes can do a blocking read on the 
fifo.  This is just the first thing that came to mind - there are 
probably other ways to do this.  


-- 
Jon Zeeff      			Ann Arbor, MI
umix!b-tech!zeeff  		zeeff@b-tech.ann-arbor.mi.us