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/file-sharing/src/network.rs

@@ -9,11 +9,10 @@ use libp2p::{
     multiaddr::Protocol,
     noise,
     request_response::{self, ProtocolSupport, RequestId, ResponseChannel},
-    swarm::{NetworkBehaviour, Swarm, SwarmBuilder, SwarmEvent},
-    tcp, yamux, PeerId, Transport,
+    swarm::{NetworkBehaviour, Swarm, SwarmEvent},
+    tcp, yamux, PeerId,
 };
 
-use libp2p::core::upgrade::Version;
 use libp2p::StreamProtocol;
 use serde::{Deserialize, Serialize};
 use std::collections::{hash_map, HashMap, HashSet};
@@ -41,18 +40,18 @@ pub(crate) async fn new(
     };
     let peer_id = id_keys.public().to_peer_id();
 
-    let transport = tcp::async_io::Transport::default()
-        .upgrade(Version::V1Lazy)
-        .authenticate(noise::Config::new(&id_keys)?)
-        .multiplex(yamux::Config::default())
-        .boxed();
-
-    // Build the Swarm, connecting the lower layer transport logic with the
-    // higher layer network behaviour logic.
-    let mut swarm = SwarmBuilder::with_async_std_executor(
-        transport,
-        Behaviour {
-            kademlia: kad::Behaviour::new(peer_id, kad::record::store::MemoryStore::new(peer_id)),
+    let mut swarm = libp2p::SwarmBuilder::with_existing_identity(id_keys)
+        .with_async_std()
+        .with_tcp(
+            tcp::Config::default(),
+            noise::Config::new,
+            yamux::Config::default,
+        )?
+        .with_behaviour(|key| Behaviour {
+            kademlia: kad::Behaviour::new(
+                peer_id,
+                kad::store::MemoryStore::new(key.public().to_peer_id()),
+            ),
             request_response: request_response::cbor::Behaviour::new(
                 [(
                     StreamProtocol::new("/file-exchange/1"),
@@ -60,10 +59,8 @@ pub(crate) async fn new(
                 )],
                 request_response::Config::default(),
             ),
-        },
-        peer_id,
-    )
-    .build();
+        })?
+        .build();
 
     swarm
         .behaviour_mut()