以相反的顺序 Ping

Question

我运行 ping pong example 在两个不同的控制台 windows 就像那个教程中描述的那样。

use libp2p::futures::StreamExt;
use libp2p::ping::{Ping, PingConfig};
use libp2p::swarm::{Swarm, SwarmEvent};
use libp2p::{identity, Multiaddr, PeerId};
use std::error::Error;

#[tokio::main]
async fn main() -> Result<(), Box<dyn Error>> {
    let local_key = identity::Keypair::generate_ed25519();
    let local_peer_id = PeerId::from(local_key.public());
    println!("Local peer id: {:?}", local_peer_id);

    let transport = libp2p::development_transport(local_key).await?;
    let behaviour = Ping::new(PingConfig::new().with_keep_alive(true));
    let mut swarm = Swarm::new(transport, behaviour, local_peer_id);

    swarm.listen_on("/ip4/0.0.0.0/tcp/0".parse()?)?;

    if let Some(addr) = std::env::args().nth(1) {
        let remote: Multiaddr = addr.parse()?;
        swarm.dial(remote)?;
        println!("Dialed {}", addr)
    }

    loop {
        match swarm.select_next_some().await {
            SwarmEvent::NewListenAddr { address, .. } => println!("Listening on {:?}", address),
            SwarmEvent::Behaviour(event) => println!("{:?}", event),
            _ => {}
        }
    }
}

控制台 1：

cargo run
Local peer id: PeerId("12D3KooWGi2AZgQL5sXDx4WYcPbtpXQDJJf2JTzEfHMKoYARohUN")
Listening on "/ip4/127.0.0.1/tcp/53912"
Listening on "/ip4/192.168.100.4/tcp/53912"
Event { peer: PeerId("12D3KooWQTRrShA41Kh7qoQYUc3G63uDZcXPSFw68AmzZqmaaHSh"), result: Ok(Pong) }
Event { peer: PeerId("12D3KooWQTRrShA41Kh7qoQYUc3G63uDZcXPSFw68AmzZqmaaHSh"), result: Ok(Ping { rtt: 1.112947ms }) }
Event { peer: PeerId("12D3KooWQTRrShA41Kh7qoQYUc3G63uDZcXPSFw68AmzZqmaaHSh"), result: Ok(Pong) }
Event { peer: PeerId("12D3KooWQTRrShA41Kh7qoQYUc3G63uDZcXPSFw68AmzZqmaaHSh"), result: Ok(Ping { rtt: 1.682508ms }) }

主机 2

cargo run -- /ip4/192.168.100.4/tcp/53912
Local peer id: PeerId("12D3KooWQTRrShA41Kh7qoQYUc3G63uDZcXPSFw68AmzZqmaaHSh")
Dialed /ip4/192.168.100.4/tcp/53912
Listening on "/ip4/127.0.0.1/tcp/53913"
Listening on "/ip4/192.168.100.4/tcp/53913"
Event { peer: PeerId("12D3KooWGi2AZgQL5sXDx4WYcPbtpXQDJJf2JTzEfHMKoYARohUN"), result: Ok(Pong) }
Event { peer: PeerId("12D3KooWGi2AZgQL5sXDx4WYcPbtpXQDJJf2JTzEfHMKoYARohUN"), result: Ok(Ping { rtt: 869.493µs }) }
Event { peer: PeerId("12D3KooWGi2AZgQL5sXDx4WYcPbtpXQDJJf2JTzEfHMKoYARohUN"), result: Ok(Pong) }
Event { peer: PeerId("12D3KooWGi2AZgQL5sXDx4WYcPbtpXQDJJf2JTzEfHMKoYARohUN"), result: Ok(Ping { rtt: 2.109459ms }) }

令我困惑的是 ping 和 pong 消息的顺序。这个例子创建了两个相互发送乒乓消息的节点。但是为什么每次我运行这些节点时它们都以 Pong msg 开头？我希望首先是 Ping，然后是 Pong 事件。我错过了什么吗？

Answer 1

如果你看一下 protocol source，你会发现协议总是 pings 在前。但是，在该示例中，仅记录了 incoming 事件。因此，两个节点首先发送未记录的 ping，开始接收 pong 响应和 ping 请求.

Answer 2

这似乎完全取决于库的语义：如果您查看 the documentation for PingSuccess（ping 操作的“成功”方面），两个变体是：

Pong Received a ping and sent back a pong.

Ping Sent a ping and received back a pong. Includes the round-trip time.

因此事件不是不对称的：“pong”表示“我收到了一个 ping 并发送了一个 pong”，“ping”表示 我收到了对我的 ping 的响应，这就是它可以报告 RTT 的原因。所以时间线是

ping ->
     <- pong
     triggers PingSuccess::Pong
triggers PingSuccess::Ping

因此您可以在此处看到顺序。

以相反的顺序 Ping

Ping in reverse order

rust

libp2p