py-libp2p/libp2p/pubsub/floodsub.py

133 lines
4.5 KiB
Python

import logging
from typing import Iterable, List, Sequence
from libp2p.network.stream.exceptions import StreamClosed
from libp2p.peer.id import ID
from libp2p.typing import TProtocol
from libp2p.utils import encode_varint_prefixed
from .pb import rpc_pb2
from .pubsub import Pubsub
from .pubsub_router_interface import IPubsubRouter
PROTOCOL_ID = TProtocol("/floodsub/1.0.0")
logger = logging.getLogger("libp2p.pubsub.floodsub")
class FloodSub(IPubsubRouter):
protocols: List[TProtocol]
pubsub: Pubsub
def __init__(self, protocols: Sequence[TProtocol]) -> None:
self.protocols = list(protocols)
self.pubsub = None
def get_protocols(self) -> List[TProtocol]:
"""
:return: the list of protocols supported by the router
"""
return self.protocols
def attach(self, pubsub: Pubsub) -> None:
"""
Attach is invoked by the PubSub constructor to attach the router to a
freshly initialized PubSub instance.
:param pubsub: pubsub instance to attach to
"""
self.pubsub = pubsub
def add_peer(self, peer_id: ID, protocol_id: TProtocol) -> None:
"""
Notifies the router that a new peer has been connected.
:param peer_id: id of peer to add
"""
def remove_peer(self, peer_id: ID) -> None:
"""
Notifies the router that a peer has been disconnected.
:param peer_id: id of peer to remove
"""
async def handle_rpc(self, rpc: rpc_pb2.RPC, sender_peer_id: ID) -> None:
"""
Invoked to process control messages in the RPC envelope. It is invoked
after subscriptions and payload messages have been processed.
:param rpc: rpc message
"""
async def publish(self, msg_forwarder: ID, pubsub_msg: rpc_pb2.Message) -> None:
"""
Invoked to forward a new message that has been validated. This is where
the "flooding" part of floodsub happens.
With flooding, routing is almost trivial: for each incoming message,
forward to all known peers in the topic. There is a bit of logic,
as the router maintains a timed cache of previous messages,
so that seen messages are not further forwarded.
It also never forwards a message back to the source
or the peer that forwarded the message.
:param msg_forwarder: peer ID of the peer who forwards the message to us
:param pubsub_msg: pubsub message in protobuf.
"""
peers_gen = self._get_peers_to_send(
pubsub_msg.topicIDs,
msg_forwarder=msg_forwarder,
origin=ID(pubsub_msg.from_id),
)
rpc_msg = rpc_pb2.RPC(publish=[pubsub_msg])
logger.debug("publishing message %s", pubsub_msg)
for peer_id in peers_gen:
stream = self.pubsub.peers[peer_id]
# FIXME: We should add a `WriteMsg` similar to write delimited messages.
# Ref: https://github.com/libp2p/go-libp2p-pubsub/blob/master/comm.go#L107
try:
await stream.write(encode_varint_prefixed(rpc_msg.SerializeToString()))
except StreamClosed:
logger.debug("Fail to publish message to %s: stream closed", peer_id)
async def join(self, topic: str) -> None:
"""
Join notifies the router that we want to receive and forward messages
in a topic. It is invoked after the subscription announcement.
:param topic: topic to join
"""
async def leave(self, topic: str) -> None:
"""
Leave notifies the router that we are no longer interested in a topic.
It is invoked after the unsubscription announcement.
:param topic: topic to leave
"""
def _get_peers_to_send(
self, topic_ids: Iterable[str], msg_forwarder: ID, origin: ID
) -> Iterable[ID]:
"""
Get the eligible peers to send the data to.
:param msg_forwarder: peer ID of the peer who forwards the message to us.
:param origin: peer id of the peer the message originate from.
:return: a generator of the peer ids who we send data to.
"""
for topic in topic_ids:
if topic not in self.pubsub.peer_topics:
continue
for peer_id in self.pubsub.peer_topics[topic]:
if peer_id in (msg_forwarder, origin):
continue
if peer_id not in self.pubsub.peers:
continue
yield peer_id