100 lines
3.0 KiB
Python
100 lines
3.0 KiB
Python
import json
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from typing import Any, Dict, Optional, Union
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from redis import Redis
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from platypush.backend import Backend
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from platypush.message import Message
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from platypush.utils import get_redis_conf
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class RedisBackend(Backend):
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"""
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Backend that reads messages from a configured Redis queue (default:
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``platypush/backend/redis``) and forwards them to the application bus.
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Useful when you have plugin whose code is executed in another process
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and can't post events or requests to the application bus.
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"""
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def __init__(
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self,
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*args,
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queue: str = 'platypush/backend/redis',
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redis_args: Optional[Dict[str, Any]] = None,
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**kwargs
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):
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"""
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:param queue: Name of the Redis queue to listen to (default:
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``platypush/backend/redis``).
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:param redis_args: Arguments that will be passed to the redis-py
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constructor (e.g. host, port, password). See
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https://redis-py.readthedocs.io/en/latest/connections.html#redis.Redis
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for supported parameters.
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"""
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super().__init__(*args, **kwargs)
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self.redis_args = redis_args or get_redis_conf()
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self.queue = queue
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self.redis: Optional[Redis] = None
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def send_message(
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self, msg: Union[str, Message], queue_name: Optional[str] = None, **_
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):
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"""
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Send a message to a Redis queue.
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:param msg: Message to send, as a ``Message`` object or a string.
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:param queue_name: Queue name to send the message to (default:
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configured ``queue`` value).
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"""
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if not self.redis:
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self.logger.warning('The Redis backend is not yet running.')
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return
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self.redis.rpush(queue_name or self.queue, str(msg))
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def get_message(self, queue_name: Optional[str] = None) -> Optional[Message]:
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queue = queue_name or self.queue
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assert self.redis, 'The Redis backend is not yet running.'
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data = self.redis.blpop(queue, timeout=1)
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if data is None:
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return None
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msg = data[1].decode()
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try:
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msg = Message.build(msg)
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except Exception as e:
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self.logger.debug(str(e))
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try:
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msg = json.loads(msg)
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except Exception as ee:
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self.logger.exception(ee)
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return msg
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def run(self):
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super().run()
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self.logger.info(
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'Initialized Redis backend on queue %s with arguments %s',
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self.queue,
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self.redis_args,
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)
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with Redis(**self.redis_args) as self.redis:
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while not self.should_stop():
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try:
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msg = self.get_message()
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if not msg:
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continue
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self.logger.info('Received message on the Redis backend: %s', msg)
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self.on_message(msg)
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except Exception as e:
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self.logger.exception(e)
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self.logger.info('Redis backend terminated')
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# vim:sw=4:ts=4:et:
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