platypush/platypush/bus/__init__.py
2018-10-23 14:20:29 +00:00

69 lines
2 KiB
Python

import logging
import threading
import time
from queue import Queue
from platypush.config import Config
from platypush.message.event import Event, StopEvent
logger = logging.getLogger(__name__)
class Bus(object):
""" Main local bus where the daemon will listen for new messages """
_MSG_EXPIRY_TIMEOUT = 60.0 # Consider a message on the bus as expired
# after one minute without being picked up
def __init__(self, on_message=None):
self.bus = Queue()
self.on_message = on_message
self.thread_id = threading.get_ident()
def post(self, msg):
""" Sends a message to the bus """
self.bus.put(msg)
def get(self):
""" Reads one message from the bus """
return self.bus.get()
def stop(self):
""" Stops the bus by sending a STOP event """
evt = StopEvent(target=Config.get('device_id'),
origin=Config.get('device_id'),
thread_id=self.thread_id)
self.post(evt)
def poll(self):
"""
Reads messages from the bus until either stop event message or KeyboardInterrupt
"""
if not self.on_message:
logger.warning('No message handlers installed, cannot poll')
return
stop=False
while not stop:
msg = self.get()
if msg.timestamp and time.time() - msg.timestamp > self._MSG_EXPIRY_TIMEOUT:
logger.debug('{} seconds old message on the bus expired, ignoring it: {}'
.format(int(time.time()-msg.timestamp), msg))
continue
try:
self.on_message(msg)
except Exception as e:
logger.error('Error on processing message {}'.format(msg))
logger.exception(e)
if isinstance(msg, StopEvent) and msg.targets_me():
logger.info('Received STOP event on the bus')
stop=True
# vim:sw=4:ts=4:et: