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