88 lines
2.7 KiB
Python
88 lines
2.7 KiB
Python
from __future__ import annotations
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import hashlib
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from dataclasses import dataclass
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from enum import Enum
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from typing import Awaitable, Callable, Self
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from framework import Framework
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from protocol.connection import (
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DuplexConnection,
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MixSimplexConnection,
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SimplexConnection,
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)
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from protocol.error import PeeringDegreeReached
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@dataclass
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class GossipConfig:
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# Expected number of peers each node must connect to if there are enough peers available in the network.
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peering_degree: int
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class Gossip:
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"""
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A gossip channel that broadcasts messages to all connected peers.
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Peers are connected via DuplexConnection.
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"""
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def __init__(
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self,
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framework: Framework,
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config: GossipConfig,
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handler: Callable[[bytes], Awaitable[None]],
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):
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self.framework = framework
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self.config = config
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self.conns: list[DuplexConnection] = []
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# A handler to process inbound messages.
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self.handler = handler
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self.packet_cache: set[bytes] = set()
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# A set just for gathering a reference of tasks to prevent them from being garbage collected.
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# https://docs.python.org/3/library/asyncio-task.html#asyncio.create_task
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self.tasks: set[Awaitable] = set()
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def can_accept_conn(self) -> bool:
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return len(self.conns) < self.config.peering_degree
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def add_conn(self, inbound: SimplexConnection, outbound: SimplexConnection):
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if not self.can_accept_conn():
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# For simplicity of the spec, reject the connection if the peering degree is reached.
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raise PeeringDegreeReached()
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conn = DuplexConnection(
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inbound,
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outbound,
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)
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self.conns.append(conn)
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task = self.framework.spawn(self.__process_inbound_conn(conn))
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self.tasks.add(task)
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async def __process_inbound_conn(self, conn: DuplexConnection):
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while True:
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msg = await conn.recv()
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if self.__check_update_cache(msg):
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continue
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await self.process_inbound_msg(msg)
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async def process_inbound_msg(self, msg: bytes):
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await self.gossip(msg)
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await self.handler(msg)
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async def gossip(self, msg: bytes):
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"""
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Gossip a message to all connected peers.
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"""
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for conn in self.conns:
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await conn.send(msg)
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def __check_update_cache(self, packet: bytes) -> bool:
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"""
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Add a message to the cache, and return True if the message was already in the cache.
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"""
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hash = hashlib.sha256(packet).digest()
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if hash in self.packet_cache:
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return True
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self.packet_cache.add(hash)
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return False
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