Added Redis backend, issue #55

platypush/backend/redis.py

@@ -0,0 +1,53 @@
+import logging
+import json
+
+from redis import Redis
+
+from platypush.backend import Backend
+from platypush.message import Message
+
+
+class RedisBackend(Backend):
+    """
+    Backend that reads messages from a configured Redis queue
+    (default: `platypush_bus_mq`) and posts them to the application bus.
+    Very useful when you have plugin whose code is executed in another process
+    and can't post events or requests to the application bus.
+    """
+
+    def __init__(self, queue='platypush_bus_mq', redis_args={}, *args, **kwargs):
+        """
+        Params:
+            queue -- Queue to poll for new messages
+            redis_args -- Arguments that will be passed to the redis-py
+                constructor (e.g. host, port, password),
+                see http://redis-py.readthedocs.io/en/latest/
+        """
+        super().__init__(*args, **kwargs)
+
+        self.queue = queue
+        self.redis_args = redis_args
+        self.redis = Redis(**self.redis_args)
+
+
+    def send_message(self, msg):
+        self.redis.rpush(self.queue, msg)
+
+
+    def run(self):
+        super().run()
+
+        logging.info('Initialized Redis backend on queue {} with arguments {}'.
+                     format(self.queue, self.redis_args))
+
+        while not self.should_stop():
+            try:
+                msg = self.redis.blpop(self.queue)
+                msg = Message.build(json.loads(msg[1].decode('utf-8')))
+                self.bus.post(msg)
+            except Exception as e:
+                logging.exception(e)
+
+
+# vim:sw=4:ts=4:et:
+