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import os, threading
from typing import Any, Dict, Iterator, Set, Tuple
from redis.client import Redis
from common.message_broker.Message import Message
from .._Backend import _Backend
DEFAULT_SERVICE_HOST = '127.0.0.1'
DEFAULT_SERVICE_PORT = 6379
DEFAULT_DATABASE_ID = 0
def get_setting(settings : Dict[str, Any], name : str, default : Any) -> Any:
value = settings.get(name, os.environ.get(name))
return default if value is None else value
class RedisBackend(_Backend):
def __init__(self, **settings) -> None: # pylint: disable=super-init-not-called
host = get_setting(settings, 'REDIS_SERVICE_HOST', DEFAULT_SERVICE_HOST)
port = get_setting(settings, 'REDIS_SERVICE_PORT', DEFAULT_SERVICE_PORT)
dbid = get_setting(settings, 'REDIS_DATABASE_ID', DEFAULT_DATABASE_ID )
self._client = Redis.from_url('redis://{host}:{port}/{dbid}'.format(host=host, port=port, dbid=dbid))
self._terminate = threading.Event()
def terminate(self) -> None:
self._terminate.set()
def publish(self, topic_name : str, message_content : str) -> None:
self._client.publish(topic_name, message_content)
def consume(self, topic_names : Set[str], consume_timeout : float) -> Iterator[Tuple[str, str]]:
pubsub = self._client.pubsub(ignore_subscribe_messages=True)
for topic_name in topic_names: pubsub.subscribe(topic_name)
while not self._terminate.is_set():
message = pubsub.get_message(ignore_subscribe_messages=True, timeout=consume_timeout)
if message is None: continue
if message['type'] not in {'message', 'pmessage'}: continue
topic = message['channel'].decode('UTF-8')
content = message['data'].decode('UTF-8')
yield Message(topic, content)
pubsub.unsubscribe()
while pubsub.get_message() is not None: pass
pubsub.close()