onoff/process.py

   1 import logging
   2 import os
   3 import signal
   4
   5 from gi.repository import GObject
   6
   7 from .common import ST_ACTIVE, ST_TRANSITION, OnoffDevice
   8
   9 logger = logging.getLogger("onoff.process")
  10
  11 class OnoffProcess(OnoffDevice):
  12     def __init__(self, command, start_wait=0, termsig=signal.SIGTERM):
  13         OnoffDevice.__init__(self)
  14         self.command = command
  15         self.start_wait = start_wait
  16         self.termsig = termsig
  17         self.state = 0
  18         self.pid = None
  19         self.starting = None # timeout event during start
  20         self.watch = None # watch event
  21
  22     def start_process(self):
  23         assert self.state == 0
  24         assert self.pid is None
  25         assert self.starting is None
  26         logger.info("starting command %s", " ".join(self.command))
  27         self.state = ST_ACTIVE|ST_TRANSITION
  28         ret = GObject.spawn_async(self.command, flags=GObject.SPAWN_SEARCH_PATH | GObject.SPAWN_DO_NOT_REAP_CHILD)
  29         self.pid = ret[0]
  30         assert self.pid
  31         logger.debug("started as pid %d", self.pid)
  32         self.watch = GObject.child_watch_add(self.pid, self.process_died)
  33         self.starting = GObject.timeout_add(1000 * self.start_wait,
  34                                             self.process_started)
  35         self.changestate(self.state)
  36
  37     def process_died(self, pid, condition):
  38         assert self.state != 0
  39         assert self.pid == pid
  40         assert self.watch is not None
  41         self.state = 0
  42         self.watch = None
  43         self.pid = None
  44         logger.info("process %d died", pid)
  45         self.changestate(self.state)
  46
  47     def process_started(self):
  48         assert self.state == ST_ACTIVE|ST_TRANSITION
  49         assert self.starting is not None
  50         self.state = ST_ACTIVE
  51         self.starting = None
  52         logger.debug("process started")
  53         self.changestate(self.state)
  54
  55     def stop_process(self):
  56         assert self.state & ST_ACTIVE
  57         assert self.pid is not None
  58         if self.state & ST_TRANSITION:
  59             logger.debug("cancelling start notification")
  60             assert self.starting is not None
  61             ret = GObject.source_remove(self.starting)
  62             assert ret
  63             self.starting = None
  64         self.state = ST_TRANSITION
  65         logger.info("killing process %d", self.pid)
  66         os.kill(self.pid, self.termsig)
  67         self.changestate(self.state)
  68
  69     def activate(self):
  70         if self.state == 0:
  71             self.start_process()
  72         else:
  73             logger.debug("not activating from state %d", self.state)
  74
  75     def deactivate(self):
  76         if self.state & ST_ACTIVE:
  77             self.stop_process()
  78         else:
  79             logger.debug("not deactivating from state %d", self.state)
  80
  81     def close(self):
  82         self.deactivate()