Module daemon

Asyncore-compatible scheduler delay function.

This is a delay function for sched that, rather than actually sleeping, executes asyncore events happening in the meantime.

After an event has occurred, rather than returning, it raises a SchedulerBreakout exception, which will force the current scheduler.run() invocation to terminate, so that we can also check for signals. The main loop will then call the scheduler run again, which will allow it to actually process any due events.

This is needed because scheduler.run() doesn't support a count=..., as asyncore loop, and the scheduler module documents throwing exceptions from inside the delay function as an allowed usage model.

Shared main function for daemons.

Parameters:

• daemon_name (string) - daemon name
• optionparser (optparse.OptionParser) - initialized optionparser with daemon-specific options (common -f -d options will be handled by this module)
• check_fn (function which accepts (options, args)) - function that checks start conditions and exits if they're not met
• prepare_fn (function which accepts (options, args)) - function that is run before forking, or None; it's result will be passed as the third parameter to exec_fn, or if None was passed in, we will just pass None to exec_fn
• exec_fn (function which accepts (options, args, prepare_results)) - function that's executed with the daemon's pid file held, and runs the daemon itself.
• multithreaded (bool) - Whether the daemon uses threads
• console_logging (boolean) - if True, the daemon will fall back to the system console if logging fails
• default_ssl_cert (string) - Default SSL certificate path
• default_ssl_key (string) - Default SSL key path
• warn_breach (bool) - issue a warning at daemon launch time, before daemonizing, about the possibility of breaking parameter privacy invariants through the otherwise helpful debug logging.