# pylint: disable=no-name-in-module import asyncio from lru import LRU from .pb import rpc_pb2 from .pubsub_notifee import PubsubNotifee class Pubsub(): # pylint: disable=too-many-instance-attributes, no-member def __init__(self, host, router, my_id, cache_size=None): """ Construct a new Pubsub object, which is responsible for handling all Pubsub-related messages and relaying messages as appropriate to the Pubsub router (which is responsible for choosing who to send messages to). Since the logic for choosing peers to send pubsub messages to is in the router, the same Pubsub impl can back floodsub, gossipsub, etc. """ self.host = host self.router = router self.my_id = my_id # Attach this new Pubsub object to the router self.router.attach(self) # Register a notifee self.peer_queue = asyncio.Queue() self.host.get_network().notify(PubsubNotifee(self.peer_queue)) # Register stream handlers for each pubsub router protocol to handle # the pubsub streams opened on those protocols self.protocols = self.router.get_protocols() for protocol in self.protocols: self.host.set_stream_handler(protocol, self.stream_handler) # Use asyncio queues for proper context switching self.incoming_msgs_from_peers = asyncio.Queue() self.outgoing_messages = asyncio.Queue() # keeps track of seen messages as LRU cache if cache_size is None: self.cache_size = 128 else: self.cache_size = cache_size self.seen_messages = LRU(self.cache_size) # Map of topics we are subscribed to blocking queues # for when the given topic receives a message self.my_topics = {} # Map of topic to peers to keep track of what peers are subscribed to self.peer_topics = {} # Create peers map, which maps peer_id (as string) to stream (to a given peer) self.peers = {} # Call handle peer to keep waiting for updates to peer queue asyncio.ensure_future(self.handle_peer_queue()) def get_hello_packet(self): """ Generate subscription message with all topics we are subscribed to only send hello packet if we have subscribed topics """ packet = rpc_pb2.RPC() if self.my_topics: for topic_id in self.my_topics: packet.subscriptions.extend([rpc_pb2.RPC.SubOpts( subscribe=True, topicid=topic_id)]) return packet.SerializeToString() async def continuously_read_stream(self, stream): """ Read from input stream in an infinite loop. Process messages from other nodes :param stream: stream to continously read from """ # TODO check on types here peer_id = str(stream.mplex_conn.peer_id) while True: incoming = (await stream.read()) rpc_incoming = rpc_pb2.RPC() rpc_incoming.ParseFromString(incoming) should_publish = False if rpc_incoming.publish: # deal with RPC.publish for message in rpc_incoming.publish: id_in_seen_msgs = (message.seqno, message.from_id) if id_in_seen_msgs not in self.seen_messages: should_publish = True self.seen_messages[id_in_seen_msgs] = 1 await self.handle_talk(message) if rpc_incoming.subscriptions: # deal with RPC.subscriptions # We don't need to relay the subscription to our # peers because a given node only needs its peers # to know that it is subscribed to the topic (doesn't # need everyone to know) for message in rpc_incoming.subscriptions: self.handle_subscription(peer_id, message) if should_publish: # relay message to peers with router await self.router.publish(peer_id, incoming) if rpc_incoming.control: # Pass rpc to router so router could perform custom logic await self.router.handle_rpc(rpc_incoming, peer_id) # Force context switch await asyncio.sleep(0) async def stream_handler(self, stream): """ Stream handler for pubsub. Gets invoked whenever a new stream is created on one of the supported pubsub protocols. :param stream: newly created stream """ # Add peer # Map peer to stream peer_id = stream.mplex_conn.peer_id self.peers[str(peer_id)] = stream self.router.add_peer(peer_id, stream.get_protocol()) # Send hello packet hello = self.get_hello_packet() await stream.write(hello) # Pass stream off to stream reader asyncio.ensure_future(self.continuously_read_stream(stream)) async def handle_peer_queue(self): """ Continuously read from peer queue and each time a new peer is found, open a stream to the peer using a supported pubsub protocol TODO: Handle failure for when the peer does not support any of the pubsub protocols we support """ while True: peer_id = await self.peer_queue.get() # Open a stream to peer on existing connection # (we know connection exists since that's the only way # an element gets added to peer_queue) stream = await self.host.new_stream(peer_id, self.protocols) # Add Peer # Map peer to stream self.peers[str(peer_id)] = stream self.router.add_peer(peer_id, stream.get_protocol()) # Send hello packet hello = self.get_hello_packet() await stream.write(hello) # Pass stream off to stream reader asyncio.ensure_future(self.continuously_read_stream(stream)) # Force context switch await asyncio.sleep(0) def handle_subscription(self, origin_id, sub_message): """ Handle an incoming subscription message from a peer. Update internal mapping to mark the peer as subscribed or unsubscribed to topics as defined in the subscription message :param origin_id: id of the peer who subscribe to the message :param sub_message: RPC.SubOpts """ if sub_message.subscribe: if sub_message.topicid not in self.peer_topics: self.peer_topics[sub_message.topicid] = [origin_id] elif origin_id not in self.peer_topics[sub_message.topicid]: # Add peer to topic self.peer_topics[sub_message.topicid].append(origin_id) else: if sub_message.topicid in self.peer_topics: if origin_id in self.peer_topics[sub_message.topicid]: self.peer_topics[sub_message.topicid].remove(origin_id) async def handle_talk(self, publish_message): """ Put incoming message from a peer onto my blocking queue :param talk: RPC.Message format """ # Check if this message has any topics that we are subscribed to for topic in publish_message.topicIDs: if topic in self.my_topics: # we are subscribed to a topic this message was sent for, # so add message to the subscription output queue # for each topic await self.my_topics[topic].put(publish_message) async def subscribe(self, topic_id): """ Subscribe ourself to a topic :param topic_id: topic_id to subscribe to """ # Already subscribed if topic_id in self.my_topics: return self.my_topics[topic_id] # Map topic_id to blocking queue self.my_topics[topic_id] = asyncio.Queue() # Create subscribe message packet = rpc_pb2.RPC() packet.subscriptions.extend([rpc_pb2.RPC.SubOpts( subscribe=True, topicid=topic_id.encode('utf-8') )]) # Send out subscribe message to all peers await self.message_all_peers(packet.SerializeToString()) # Tell router we are joining this topic await self.router.join(topic_id) # Return the asyncio queue for messages on this topic return self.my_topics[topic_id] async def unsubscribe(self, topic_id): """ Unsubscribe ourself from a topic :param topic_id: topic_id to unsubscribe from """ # Return if we already unsubscribed from the topic if topic_id not in self.my_topics: return # Remove topic_id from map if present del self.my_topics[topic_id] # Create unsubscribe message packet = rpc_pb2.RPC() packet.subscriptions.extend([rpc_pb2.RPC.SubOpts( subscribe=False, topicid=topic_id.encode('utf-8') )]) # Send out unsubscribe message to all peers await self.message_all_peers(packet.SerializeToString()) # Tell router we are leaving this topic await self.router.leave(topic_id) async def message_all_peers(self, rpc_msg): """ Broadcast a message to peers :param raw_msg: raw contents of the message to broadcast """ # Broadcast message for peer in self.peers: stream = self.peers[peer] # Write message to stream await stream.write(rpc_msg)