64 lines
1.6 KiB
Python
64 lines
1.6 KiB
Python
import logging
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from collections import defaultdict
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from itertools import chain
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from threading import Thread, RLock
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ALL_EVENTS = '*'
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class EventBus:
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def __init__(self):
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self.listeners = defaultdict(list)
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self.lock = RLock()
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self.logger =logging.getLogger(__name__)
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def fire(self, event):
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assert isinstance(event, Event), "event needs to be an instance of Event"
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# We dont want the eventbus to be blocking,
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# We dont want the eventbus to crash when one of its listeners throws an Exception
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# So run in a thread
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def run():
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self.lock.acquire()
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self.logger.info("{} event received: {}".format(event.eventType, event.data))
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for callback in chain(self.listeners[ALL_EVENTS], self.listeners[event.eventType]):
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callback(event)
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if event.removeListener:
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if callback in self.listeners[ALL_EVENTS]:
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self.listeners[ALL_EVENTS].remove(callback)
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if callback in self.listeners[event.eventType]:
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self.listeners[event.eventType].remove(callback)
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event.removeListener = False
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if event.stopPropegating:
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break
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self.lock.release()
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Thread(target=run).start()
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def listen(self, event_type, callback):
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self.lock.acquire()
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self.listeners[event_type].append(callback)
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self.logger.info("New listener added for event {}. Total: {}".format(event_type, len(self.listeners[event_type])))
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self.lock.release()
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class Event:
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def __init__(self, eventType, data):
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self.eventType = eventType
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self.data = data
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self.stopPropegating = False
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self.removeListener = False
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def __str__(self):
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return str([self.eventType, self.data])
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