feat: refactor distributed-key-value-store example (#5652)

## Description

ref #4449 

Refactored distributed-key-value-store example to use `tokio` instead of
`async-std`

## Change checklist

<!-- Please add a Changelog entry in the appropriate crates and bump the
crate versions if needed. See
<https://github.com/libp2p/rust-libp2p/blob/master/docs/release.md#development-between-releases>-->

- [x] I have performed a self-review of my own code
- [x] I have made corresponding changes to the documentation
- [x] I have added tests that prove my fix is effective or that my
feature works
- [x] A changelog entry has been made in the appropriate crates

examples/distributed-key-value-store/Cargo.toml

@@ -9,10 +9,10 @@ license = "MIT"
 release = false
 
 [dependencies]
-async-std = { version = "1.12", features = ["attributes"] }
+tokio = { workspace = true, features = ["full"] }
 async-trait = "0.1"
 futures = { workspace = true }
-libp2p = { path = "../../libp2p", features = [ "async-std", "dns", "kad", "mdns", "noise", "macros", "tcp", "yamux"] }
+libp2p = { path = "../../libp2p", features = [ "tokio", "dns", "kad", "mdns", "noise", "macros", "tcp", "yamux"] }
 tracing = { workspace = true }
 tracing-subscriber = { workspace = true, features = ["env-filter"] }
 

examples/distributed-key-value-store/src/main.rs

@@ -20,8 +20,7 @@
 
 #![doc = include_str!("../README.md")]
 
-use async_std::io;
-use futures::{prelude::*, select};
+use futures::stream::StreamExt;
 use libp2p::kad;
 use libp2p::kad::store::MemoryStore;
 use libp2p::kad::Mode;
@@ -32,9 +31,13 @@ use libp2p::{
 };
 use std::error::Error;
 use std::time::Duration;
+use tokio::{
+    io::{self, AsyncBufReadExt},
+    select,
+};
 use tracing_subscriber::EnvFilter;
 
-#[async_std::main]
+#[tokio::main]
 async fn main() -> Result<(), Box<dyn Error>> {
     let _ = tracing_subscriber::fmt()
         .with_env_filter(EnvFilter::from_default_env())
@@ -44,11 +47,11 @@ async fn main() -> Result<(), Box<dyn Error>> {
     #[derive(NetworkBehaviour)]
     struct Behaviour {
         kademlia: kad::Behaviour<MemoryStore>,
-        mdns: mdns::async_io::Behaviour,
+        mdns: mdns::tokio::Behaviour,
     }
 
     let mut swarm = libp2p::SwarmBuilder::with_new_identity()
-        .with_async_std()
+        .with_tokio()
         .with_tcp(
             tcp::Config::default(),
             noise::Config::new,
@@ -60,7 +63,7 @@ async fn main() -> Result<(), Box<dyn Error>> {
                     key.public().to_peer_id(),
                     MemoryStore::new(key.public().to_peer_id()),
                 ),
-                mdns: mdns::async_io::Behaviour::new(
+                mdns: mdns::tokio::Behaviour::new(
                     mdns::Config::default(),
                     key.public().to_peer_id(),
                 )?,
@@ -72,15 +75,17 @@ async fn main() -> Result<(), Box<dyn Error>> {
     swarm.behaviour_mut().kademlia.set_mode(Some(Mode::Server));
 
     // Read full lines from stdin
-    let mut stdin = io::BufReader::new(io::stdin()).lines().fuse();
+    let mut stdin = io::BufReader::new(io::stdin()).lines();
 
     // Listen on all interfaces and whatever port the OS assigns.
     swarm.listen_on("/ip4/0.0.0.0/tcp/0".parse()?)?;
 
     // Kick it off.
     loop {
         select! {
-        line = stdin.select_next_some() => handle_input_line(&mut swarm.behaviour_mut().kademlia, line.expect("Stdin not to close")),
+        Ok(Some(line)) = stdin.next_line() => {
+            handle_input_line(&mut swarm.behaviour_mut().kademlia, line);
+        }
         event = swarm.select_next_some() => match event {
             SwarmEvent::NewListenAddr { address, .. } => {
                 println!("Listening in {address:?}");