initial suggestions re. compiler server (bug #6565)

[Dave Brolley]

Thanks for your comments!

Frank Ch. Eigler wrote:
> Hi, Dave -
>
> (Background: we're prototyping a compile server split of stap, to
> allow a central network server to perform arbitrary script translation
> and compilation for a machine without local debuginfo nor compiler.
> It'll be useful later for unprivileged user-space probing too.  Some
> prototype code is in bug #6565.)
>
>
> Here are some suggestions about the prototype code.
>
> * The code might as well get checked into git and be developed there;
>   it does not need to be make-install'd or systemtap.spec'd until
>   later.
>   
ok
> * The scripts are not #! /bin/sh but rather technically #! /bin/bash.
>   
ok
> * The wire protocol can probably do everything based on two
>   unidirectional bits of communication: one client->server tar.gz
>   file to encode the arguments, given tapsets, the script; and one
>   server->client tar.gz file to encode the results (.ko/.c files,
>   stdout, stderr).
>   
Thats' essentially what happens now. The extra messages are needed right 
now because of the rsync hack. The
client needs to know where to write files to and where to read them from 
on the server's host.
> * It should be testable now even without networks via dejagnu making
>   two named pipes ("mknod p FOO.1; mknod p FOO.2") and then starting
>   the server & client scripts with redirected stdout/stdin.
>   
I'll look into this.
> * The networking aspect of it need not go through xinetd.  If we can't
>   find a suitable shell-script-invokable tool to create/attach-to
>   listening sockets, then perhaps a few-liner perl script could do the
>   job.  That same perl script can use avahi-publish-service to push
>   the actual (random) listening port number into mdns, so that 65000
>   number need not be hardcoded anywhere.  Clients would find the
>   server by abstract type (not _http._tcp but something like
>   _systemtap._tcp) and name, and particularly with some cleverly
>   chosen TXT description that should identify the server's assigned
>   cross-compilation target.
>
> * The client is not using the right avahi search entry points AFAIK.
>   The avahi-discovery gui can pick up the full address/txt bits, and
>   those are what the client will need to choose its favorite server.
>   There must be some other command-line tool for that.
>   
Yes. I discovered some of this earlier this week, hence my comment about 
fixing the hard coded port number.
> - FChE
>   
Thanks again for you ideas!

Dave