Add write_only argument to Kombu and Redis manager classes

Author: miguelgrinberg

docs/index.rst

@@ -233,10 +233,11 @@ type of installation, each server processes owns the connections to a subset
 of the clients. To make broadcasting work in this environment, the servers
 communicate with each other through the message queue.
 
-The message queue service needs to be installed and configured separately. By
-default, the server uses `Kombu <http://kombu.readthedocs.org/en/latest/>`_
-to access the message queue, so any message queue supported by this package
-can be used. Kombu can be installed with pip::
+The message queue service needs to be installed and configured separately. One
+of the options offered by this package is to use
+`Kombu <http://kombu.readthedocs.org/en/latest/>`_ to access the message
+queue, which means that any message queue supported by this package can be
+used. Kombu can be installed with pip::
 
     pip install kombu
 
@@ -252,29 +253,40 @@ To configure a Socket.IO server to connect to a message queue, the
 following example instructs the server to connect to a Redis service running
 on the same host and on the default port::
 
-    redis = socketio.KombuManager('redis://')
-    sio = socketio.Server(client_manager=redis)
+    mgr = socketio.KombuManager('redis://')
+    sio = socketio.Server(client_manager=mgr)
 
 For a RabbitMQ queue also running on the local server with default
 credentials, the configuration is as follows::
 
-    amqp = socketio.KombuManager('amqp://')
-    sio = socketio.Server(client_manager=amqp)
+    mgr = socketio.KombuManager('amqp://')
+    sio = socketio.Server(client_manager=mgr)
 
-The arguments passed to the ``KombuManager`` constructor are passed directly
-to Kombu's `Connection object
+The URL passed to the ``KombuManager`` constructor is passed directly to
+Kombu's `Connection object
 <http://kombu.readthedocs.org/en/latest/userguide/connections.html>`_, so
 the Kombu documentation should be consulted for information on how to
 connect to the message queue appropriately.
 
+If the use of Kombu is not desired, native Redis support is also offered
+through the ``RedisManager`` class. This class takes the same arguments as
+``KombuManager``, but connects directly to a Redis store using the queue's
+pub/sub functionality::
+
+
+    mgr = socketio.RedisManager('redis://')
+    sio = socketio.Server(client_manager=mgr)
+
 If multiple Sokcet.IO servers are connected to a message queue, they
 automatically communicate with each other and manage a combined client list,
 without any need for additional configuration. To have a process other than
-the server connect to the queue to emit a message, the same ``KombuManager``
-class can be used as standalone object. For example::
+a server connect to the queue to emit a message, the same ``KombuManager``
+and ``RedisManager`` classes can be used as standalone object. In this case,
+the ``write_only`` argument should be set to ``True`` to disable the creation
+of a listening thread. For example::
 
-    # connect to the redis queue
-    redis = socketio.KombuManager('redis://localhost:6379/')
+    # connect to the redis queue through Kombu
+    redis = socketio.KombuManager('redis://', write_only=True)
     
     # emit an event
     redis.emit('my event', data={'foo': 'bar'}, room='my room')

socketio/kombu_manager.py

@@ -31,19 +31,23 @@ class KombuManager(PubSubManager):  # pragma: no cover
                 connection URLs.
     :param channel: The channel name on which the server sends and receives
                     notifications. Must be the same in all the servers.
+    :param write_only: If set ot ``True``, only initialize to emit events. The
+                       default of ``False`` initializes the class for emitting
+                       and receiving.
     """
     name = 'kombu'
 
     def __init__(self, url='amqp://guest:guest@localhost:5672//',
-                 channel='socketio'):
+                 channel='socketio', write_only=False):
         if kombu is None:
             raise RuntimeError('Kombu package is not installed '
                                '(Run "pip install kombu" in your '
                                'virtualenv).')
         self.kombu = kombu.Connection(url)
         self.exchange = kombu.Exchange(channel, type='fanout', durable=False)
         self.queue = kombu.Queue(str(uuid.uuid4()), self.exchange)
-        super(KombuManager, self).__init__(channel=channel)
+        super(KombuManager, self).__init__(channel=channel,
+                                           write_only=write_only)
 
     def _publish(self, data):
         with self.kombu.SimpleQueue(self.queue) as queue:

socketio/pubsub_manager.py

@@ -24,14 +24,16 @@ class PubSubManager(BaseManager):
     """
     name = 'pubsub'
 
-    def __init__(self, channel='socketio'):
+    def __init__(self, channel='socketio', write_only=False):
         super(PubSubManager, self).__init__()
         self.channel = channel
+        self.write_only = write_only
         self.host_id = uuid.uuid4().hex
 
     def initialize(self, server):
         super(PubSubManager, self).initialize(server)
-        self.thread = self.server.start_background_task(self._thread)
+        if not self.write_only:
+            self.thread = self.server.start_background_task(self._thread)
         self.server.logger.info(self.name + ' backend initialized.')
 
     def emit(self, event, data, namespace=None, room=None, skip_sid=None,

socketio/redis_manager.py

@@ -22,20 +22,26 @@ class RedisManager(PubSubManager):  # pragma: no cover
         url = 'redis://hostname:port/0'
         server = socketio.Server(client_manager=socketio.RedisManager(url))
 
-    :param url: The connection URL for the Redis server.
+    :param url: The connection URL for the Redis server. For a default Redis
+                store running on the same host, use ``redis://``.
     :param channel: The channel name on which the server sends and receives
                     notifications. Must be the same in all the servers.
+    :param write_only: If set ot ``True``, only initialize to emit events. The
+                       default of ``False`` initializes the class for emitting
+                       and receiving.
     """
     name = 'redis'
 
-    def __init__(self, url='redis://localhost:6379/0', channel='socketio'):
+    def __init__(self, url='redis://localhost:6379/0', channel='socketio',
+                 write_only=False):
         if redis is None:
             raise RuntimeError('Redis package is not installed '
                                '(Run "pip install redis" in your '
                                'virtualenv).')
         self.redis = redis.Redis.from_url(url)
         self.pubsub = self.redis.pubsub()
-        super(RedisManager, self).__init__(channel=channel)
+        super(RedisManager, self).__init__(channel=channel,
+                                           write_only=write_only)
 
     def _publish(self, data):
         return self.redis.publish(self.channel, pickle.dumps(data))

tests/test_pubsub_manager.py

@@ -29,6 +29,14 @@ def test_custom_init(self):
         self.assertEqual(pubsub.channel, 'foo')
         self.assertEqual(len(pubsub.host_id), 32)
 
+    def test_write_only_init(self):
+        mock_server = mock.MagicMock()
+        pm = pubsub_manager.PubSubManager(write_only=True)
+        pm.initialize(mock_server)
+        self.assertEqual(pm.channel, 'socketio')
+        self.assertEqual(len(pm.host_id), 32)
+        self.assertEqual(pm.server.start_background_task.call_count, 0)
+
     def test_emit(self):
         self.pm.emit('foo', 'bar')
         self.pm._publish.assert_called_once_with(