Re: gcj: SignalListener, process pid, ...

[Andrew Haley <aph at redhat dot com>]

Tom Tromey writes:
 > >>>>> "Erik" == Erik Poupaert <erik.poupaert@freestyler-toolkit.org> writes:
 > 
 > Erik> For long-running processes (serverside programs) on linux, I
 > Erik> need to "signal" them with -HUP to reread their config files,
 > Erik> and "-TERM" to stop operating. How can I respond to signals in
 > Erik> gcj? I mean, is there a class like "SignalListener" anywhere?
 > Erik> Do I need to wrap something with CNI? Has anybody done that
 > Erik> already?
 > 
 > I don't know of any existing code to do it.  You'd have to write it
 > yourself.

This is tricky because an asynchronous signal handler can't do
anything that might try to acquire a lock because it might block.
That means that notify() couldn't be directly used.  I guess the
handler could set a static variable somewhere.  That's probably
adequate for this particular job.

 > Erik> Has anybody already created a CNI-based posix-oriented library
 > Erik> that makes the classical unix concepts available in gcj
 > Erik> (environment vars, signals, pid, essential areas in libc,...). I
 > Erik> wonder how you can write decent server programs for unix/linux,
 > Erik> without it?
 > 
 > People have talked about POSIX wrappers for java (and libgcj), but I
 > don't recall seeing an implementation.  There's a thread about this in
 > our archives (which you participated in :-), e.g.:
 > 
 >     http://gcc.gnu.org/ml/java/2003-04/msg00441.html

Surely it's a simple matter to write native methods -- that's what
JNI/CNI is for.  If this is a server for POSIX, who will care that
it's not 100% Pure Java (TM) ?

Andrew.