共计 3874 个字符,预计需要花费 10 分钟才能阅读完成。
本文以 floodsub 为例,探讨如何在 libp2p-rs 上开发新协定,具体代码请查看源码。
实现两个 trait
在 libp2p-rs 中,swarm 提供了两个 trait:
- Notifiee 用于接管 swarm 的告诉,当有新的连贯创立或者连贯敞开时,swarm 会调用 connected() 或者 disconnected();
- ProtocolHandler 用于读写协定的数据,协定协商胜利后,swarm 会调用 handle()。
/// Notifiee is an trait for an object wishing to receive notifications from swarm
pub trait Notifiee {
/// called when a connection opened
fn connected(&mut self, _conn: &mut Connection) {}
/// called when a connection closed
fn disconnected(&mut self, _conn: &mut Connection) {}}
/// Common trait for upgrades that can be applied on inbound substreams, outbound substreams,
/// or both.
/// Possible upgrade on a connection or substream.
#[async_trait]
pub trait ProtocolHandler: UpgradeInfo + Notifiee {
/// After we have determined that the remote supports one of the protocols we support, this
/// method is called to start handling the inbound. Swarm will start invoking this method
/// in a newly spawned task.
///
/// The `info` is the identifier of the protocol, as produced by `protocol_info`.
async fn handle(&mut self, stream: Substream, info: <Self as UpgradeInfo>::Info) -> Result<(), Box<dyn Error>>;
/// This is to provide a clone method for the trait object.
fn box_clone(&self) -> IProtocolHandler;
}
floodsub handler 实现 Notifiee 和 ProtocolHandler
#[derive(Clone)]
pub struct Handler {
incoming_tx: mpsc::UnboundedSender<RPC>,
new_peer: mpsc::UnboundedSender<PeerEvent>,
}
impl Handler {pub(crate) fn new(incoming_tx: mpsc::UnboundedSender<RPC>, new_peer: mpsc::UnboundedSender<PeerEvent>) -> Self {Handler { incoming_tx, new_peer}
}
}
impl UpgradeInfo for Handler {type Info = &'static [u8];
fn protocol_info(&self) -> Vec<Self::Info> {vec![FLOOD_SUB_ID]
}
}
impl Notifiee for Handler {fn connected(&mut self, conn: &mut Connection) {let peer_id = conn.remote_peer();
let mut new_peers = self.new_peer.clone();
task::spawn(async move {let _ = new_peers.send(PeerEvent::NewPeer(peer_id)).await;
});
}
}
#[async_trait]
impl ProtocolHandler for Handler {async fn handle(&mut self, mut stream: Substream, _info: <Self as UpgradeInfo>::Info) -> Result<(), Box<dyn Error>> {
loop {
/* recv, decode and send to msg process mainloop */
self.incoming_tx.send(rpc).await.map_err(|_| FloodsubDecodeError::ProtocolExit)?;
}
}
fn box_clone(&self) -> IProtocolHandler {Box::new(self.clone())
}
}
注册到 swarm
let floodsub = FloodSub::new(FloodsubConfig::new(local_peer_id));
let handler = floodsub.handler();
let mut swarm = Swarm::new(local_key.public()).with_protocol(Box::new(handler))
还须要做什么
简略的协定,比方 echo,那么所有事件都在 ProtocolHandler.handle() 中解决即可,到这里就完结了。
略微简单的协定,比方 floodsub,最好将 swarm 的告诉和收到的数据,发送到音讯解决主循环进行解决,实时更新状态;
impl floodsub {pub fn start(mut self, control: Swarm_Control) {self.control = Some(control);
// well, self 'move' explicitly,
let mut floodsub = self;
task::spawn(async move {let _ = floodsub.process_loop().await;
});
}
/// Message Process Loop.
pub async fn process_loop(&mut self) -> Result<()> {
loop {
select! {cmd = self.peer_rx.next() => {self.handle_peer_event(cmd).await;
}
rpc = self.incoming_rx.next() => {self.handle_incoming_rpc(rpc).await?;
}
cmd = self.control_rx.next() => {self.on_control_command(cmd).await?;
}
sub = self.cancel_rx.next() => {self.un_subscribe(sub).await?;
}
}
}
}
}
从下面能够看到,floodsub 音讯解决主循环运行在一个 task 外面,start() 时须要将 self 传递进去,因而后续的公布订阅等操作只能通过 channel 发消息,这就是 control 和 handler 包裹 channel 的起因。
#[derive(Clone)]
pub struct Control {
config: FloodsubConfig,
control_sender: mpsc::UnboundedSender<ControlCommand>,
}
impl Control {
/// Subscribe to messages on a given topic.
pub async fn subscribe(&mut self, topic: Topic) -> Option<Subscription> {let (tx, rx) = oneshot::channel();
self.control_sender
.send(ControlCommand::Subscribe(topic, tx))
.await
.expect("control send subscribe");
rx.await.expect("Subscribe")
}
}
当新的连贯创立时,floodsub 会被动创立流,协商通过后向对方发送本节点感兴趣的 topic。因而这里须要 swarm 的 control。
self.control.as_mut().unwrap().new_stream(pid, vec![FLOOD_SUB_ID]).await;
总结
在 libp2p-rs 下面开发简略的协定,只须要两步,对于略微简单的协定,须要 handler 和 control 这类包裹 channel 的构造,将音讯发送到协定音讯解决主循环,以驱动整个协定的运行,实现特定的性能。
Netwarps 由国内资深的云计算和分布式技术开发团队组成,该团队在金融、电力、通信及互联网行业有十分丰盛的落地教训。Netwarps 目前在深圳、北京均设立了研发核心,团队规模 30+,其中大部分为具备十年以上开发教训的技术人员,别离来自互联网、金融、云计算、区块链以及科研机构等业余畛域。
Netwarps 专一于平安存储技术产品的研发与利用,次要产品有去中心化文件系统(DFS)、去中心化计算平台(DCP),致力于提供基于去中心化网络技术实现的分布式存储和分布式计算平台,具备高可用、低功耗和低网络的技术特点,实用于物联网、工业互联网等场景。
公众号:Netwarps