terom@31: """
terom@31:     Syslog handling.
terom@31: """
terom@31: 
terom@43: import select
terom@43: 
terom@31: import logging; log = logging.getLogger('pvl.syslog.source')
terom@31: 
terom@31: class SyslogSource (object) :
terom@31:     """
terom@31:         A source of syslog items.
terom@31:     """
terom@31:     
terom@43:     def __init__ (self, source, parser, poll=None) :
terom@31:         """
terom@31:             Using given underlying line source.
terom@43: 
terom@43:                 source          - file-like object with poll() and iter()
terom@43:                 parser          - process() bytes -> messages
terom@43:                 poll            - using given polling style:
terom@43:                     True            - select() source
terom@43:                     float           - given interval
terom@43:                     None/False      - single-shot
terom@31:         """
terom@31: 
terom@31:         self.source = source
terom@31:         self.parser = parser
terom@31: 
terom@43:         self._poll = poll
terom@31: 
terom@31:     def __iter__ (self) :
terom@31:         """
terom@31:             Read syslog messages from source.
terom@31:         """
terom@31:         
terom@31:         # directly iter across source
terom@43:         for item in self.parser(self.source) :
terom@31:             yield item
terom@43:         
terom@43:     def poll (self, timeout=None) :
terom@43:         """
terom@43:             Poll source for input, with given timeout in seconds (float).
terom@43: 
terom@43:             A timeout of None indicates to block forever, False indicates to never block.
terom@43: 
terom@43:             Returns True if we have input waiting, False on timeout with no input. None on indeterminate.
terom@43:         """
terom@43: 
terom@43:         read = write = ()
terom@43:         
terom@43:         if timeout is True :
terom@43:             timeout = None
terom@43:             read += (self.source, )
terom@43: 
terom@43:         elif timeout is False :
terom@43:             timeout = 0.0
terom@43: 
terom@43:         log.debug("%f", timeout)
terom@43:     
terom@43:         # select
terom@43:         read, write, ex = select.select(read, write, [], timeout)
terom@43: 
terom@43:         if read :
terom@43:             return True
terom@43: 
terom@43:         else :
terom@43:             # timeout
terom@43:             return False
terom@43: 
terom@43:     def loop (self) :
terom@43:         """
terom@43:             Continuously read items from syslog source, blocking as suitable.
terom@43: 
terom@43:             Returns once no more lines are available.
terom@43: 
terom@43:             XXX: reconnect?
terom@43:         """
terom@43:         
terom@43:         # mainloop
terom@43:         while True :
terom@43:             # pull in messages
terom@43:             for item in self :
terom@43:                 yield item
terom@31:             
terom@43:             # poll
terom@43:             if self._poll :
terom@43:                 # wait
terom@43:                 self.poll(self._poll)
terom@43:             else :
terom@43:                 # done
terom@43:                 break
terom@43: 
terom@43:             log.debug("tick")
terom@43: 
terom@43:         log.debug("exit")
terom@43:     
terom@43:     def stop (self) :
terom@43:         """
terom@43:             Stop loop after current iteration.
terom@43:         """
terom@43: 
terom@43:         self._poll = False
terom@43: 
terom@43:     def main (self) :
terom@43:         """
terom@43:             Mainloop.
terom@43:         """
terom@43: 
terom@43:         # TODO: SIGINT -> stop()
terom@43:         return loop()