[ZODB-Dev] ZEO signal handling cleanup

[Guido van Rossum]

> I'm trying to clean up signal handling in the ZEO storage server.
> 
> Here's the current situation:
> 
>   SIGTERM - terminate cleanly
>   SIGINT  - restart cleanly
>   SIGHUP  - close and reopen the log file
> 
> I propose that in the final ZEO 2 release it will be like this:
> 
>   SIGTERM - terminate cleanly (unchanged)
>   SIGHUP  - restart cleanly
>   SIGUSR1 - close and reopen the log file

I've done this now, except using SIGUSR2 to reopen the log file.

Other changes:

- The pid file only contains the pid of the zdaemon process.

- When using zdaemon, the storage server chdir's into the var
  directory (or INSTANCE_HOME).  The directory name is logged.

--Guido van Rossum (home page: http://www.python.org/~guido/)