feat(libp2p): add SwarmBuilder

Introduce the new `libp2p::SwarmBuilder`. Users should use the new `libp2p::SwarmBuilder` instead of the now deprecated `libp2p::swarm::SwarmBuilder`. See `libp2p::SwarmBuilder` docs on how to use the new builder.

Fixes #3657.
Fixes #3563.
Fixes #3179.

Pull-Request: #4120.

examples/chat/src/main.rs

@@ -20,14 +20,8 @@
 
 #![doc = include_str!("../README.md")]
 
-use futures::{future::Either, stream::StreamExt};
-use libp2p::{
-    core::{muxing::StreamMuxerBox, transport::OrTransport, upgrade},
-    gossipsub, identity, mdns, noise, quic,
-    swarm::NetworkBehaviour,
-    swarm::{SwarmBuilder, SwarmEvent},
-    tcp, yamux, PeerId, Transport,
-};
+use futures::stream::StreamExt;
+use libp2p::{gossipsub, mdns, noise, swarm::NetworkBehaviour, swarm::SwarmEvent, tcp, yamux};
 use std::collections::hash_map::DefaultHasher;
 use std::error::Error;
 use std::hash::{Hash, Hasher};
@@ -43,58 +37,46 @@ struct MyBehaviour {
 
 #[tokio::main]
 async fn main() -> Result<(), Box<dyn Error>> {
-    // Create a random PeerId
-    env_logger::init();
-    let id_keys = identity::Keypair::generate_ed25519();
-    let local_peer_id = PeerId::from(id_keys.public());
+    let mut swarm = libp2p::SwarmBuilder::with_new_identity()
+        .with_tokio()
+        .with_tcp(
+            tcp::Config::default(),
+            noise::Config::new,
+            yamux::Config::default,
+        )?
+        .with_quic()
+        .with_behaviour(|key| {
+            // To content-address message, we can take the hash of message and use it as an ID.
+            let message_id_fn = |message: &gossipsub::Message| {
+                let mut s = DefaultHasher::new();
+                message.data.hash(&mut s);
+                gossipsub::MessageId::from(s.finish().to_string())
+            };
 
-    // Set up an encrypted DNS-enabled TCP Transport over the yamux protocol.
-    let tcp_transport = tcp::tokio::Transport::new(tcp::Config::default().nodelay(true))
-        .upgrade(upgrade::Version::V1Lazy)
-        .authenticate(noise::Config::new(&id_keys).expect("signing libp2p-noise static keypair"))
-        .multiplex(yamux::Config::default())
-        .timeout(std::time::Duration::from_secs(20))
-        .boxed();
-    let quic_transport = quic::tokio::Transport::new(quic::Config::new(&id_keys));
-    let transport = OrTransport::new(quic_transport, tcp_transport)
-        .map(|either_output, _| match either_output {
-            Either::Left((peer_id, muxer)) => (peer_id, StreamMuxerBox::new(muxer)),
-            Either::Right((peer_id, muxer)) => (peer_id, StreamMuxerBox::new(muxer)),
-        })
-        .boxed();
+            // Set a custom gossipsub configuration
+            let gossipsub_config = gossipsub::ConfigBuilder::default()
+                .heartbeat_interval(Duration::from_secs(10)) // This is set to aid debugging by not cluttering the log space
+                .validation_mode(gossipsub::ValidationMode::Strict) // This sets the kind of message validation. The default is Strict (enforce message signing)
+                .message_id_fn(message_id_fn) // content-address messages. No two messages of the same content will be propagated.
+                .build()
+                .map_err(|msg| io::Error::new(io::ErrorKind::Other, msg))?; // Temporary hack because `build` does not return a proper `std::error::Error`.
 
-    // To content-address message, we can take the hash of message and use it as an ID.
-    let message_id_fn = |message: &gossipsub::Message| {
-        let mut s = DefaultHasher::new();
-        message.data.hash(&mut s);
-        gossipsub::MessageId::from(s.finish().to_string())
-    };
+            // build a gossipsub network behaviour
+            let gossipsub = gossipsub::Behaviour::new(
+                gossipsub::MessageAuthenticity::Signed(key.clone()),
+                gossipsub_config,
+            )?;
 
-    // Set a custom gossipsub configuration
-    let gossipsub_config = gossipsub::ConfigBuilder::default()
-        .heartbeat_interval(Duration::from_secs(10)) // This is set to aid debugging by not cluttering the log space
-        .validation_mode(gossipsub::ValidationMode::Strict) // This sets the kind of message validation. The default is Strict (enforce message signing)
-        .message_id_fn(message_id_fn) // content-address messages. No two messages of the same content will be propagated.
-        .build()
-        .expect("Valid config");
+            let mdns =
+                mdns::tokio::Behaviour::new(mdns::Config::default(), key.public().to_peer_id())?;
+            Ok(MyBehaviour { gossipsub, mdns })
+        })?
+        .build();
 
-    // build a gossipsub network behaviour
-    let mut gossipsub = gossipsub::Behaviour::new(
-        gossipsub::MessageAuthenticity::Signed(id_keys),
-        gossipsub_config,
-    )
-    .expect("Correct configuration");
     // Create a Gossipsub topic
     let topic = gossipsub::IdentTopic::new("test-net");
     // subscribes to our topic
-    gossipsub.subscribe(&topic)?;
-
-    // Create a Swarm to manage peers and events
-    let mut swarm = {
-        let mdns = mdns::tokio::Behaviour::new(mdns::Config::default(), local_peer_id)?;
-        let behaviour = MyBehaviour { gossipsub, mdns };
-        SwarmBuilder::with_tokio_executor(transport, behaviour, local_peer_id).build()
-    };
+    swarm.behaviour_mut().gossipsub.subscribe(&topic)?;
 
     // Read full lines from stdin
     let mut stdin = io::BufReader::new(io::stdin()).lines();