feat(swarm): allow configuration to idle connection timeout

Previously, a connection would be shut down immediately as soon as its `ConnectionHandler` reports `KeepAlive::No`. As we have gained experience with libp2p, it turned out that this isn't ideal.

For one, tests often need to keep connections alive longer than the configured protocols require. Plus, some usecases require connections to be kept alive in general.

Both of these needs are currently served by the `keep_alive::Behaviour`. That one does essentially nothing other than statically returning `KeepAlive::Yes` from its `ConnectionHandler`.

It makes much more sense to deprecate `keep_alive::Behaviour` and instead allow users to globally configure an `idle_conncetion_timeout` on the `Swarm`. This timeout comes into effect once a `ConnectionHandler` reports `KeepAlive::No`. To start with, this timeout is 0. Together with libp2p#3844, this will allow us to move towards a much more aggressive closing of idle connections, together with a more ergonomic way of opting out of this behaviour.

Fixes libp2p#4121.

Pull-Request: libp2p#4161.

examples/browser-webrtc/src/main.rs

@@ -13,11 +13,12 @@ use libp2p::{
     identity,
     multiaddr::{Multiaddr, Protocol},
     ping,
-    swarm::{keep_alive, NetworkBehaviour, SwarmBuilder, SwarmEvent},
+    swarm::{SwarmBuilder, SwarmEvent},
 };
 use libp2p_webrtc as webrtc;
 use rand::thread_rng;
 use std::net::{Ipv4Addr, SocketAddr};
+use std::time::Duration;
 use tower_http::cors::{Any, CorsLayer};
 
 #[tokio::main]
@@ -36,12 +37,10 @@ async fn main() -> anyhow::Result<()> {
     .map(|(peer_id, conn), _| (peer_id, StreamMuxerBox::new(conn)))
     .boxed();
 
-    let behaviour = Behaviour {
-        ping: ping::Behaviour::new(ping::Config::new()),
-        keep_alive: keep_alive::Behaviour,
-    };
-
-    let mut swarm = SwarmBuilder::with_tokio_executor(transport, behaviour, local_peer_id).build();
+    let mut swarm =
+        SwarmBuilder::with_tokio_executor(transport, ping::Behaviour::default(), local_peer_id)
+            .idle_connection_timeout(Duration::from_secs(30)) // Allows us to observe the pings.
+            .build();
 
     let address_webrtc = Multiaddr::from(Ipv4Addr::UNSPECIFIED)
         .with(Protocol::Udp(0))
@@ -84,12 +83,6 @@ async fn main() -> anyhow::Result<()> {
     Ok(())
 }
 
-#[derive(NetworkBehaviour)]
-struct Behaviour {
-    ping: ping::Behaviour,
-    keep_alive: keep_alive::Behaviour,
-}
-
 #[derive(rust_embed::RustEmbed)]
 #[folder = "$CARGO_MANIFEST_DIR/static"]
 struct StaticFiles;

examples/metrics/src/main.rs

@@ -26,12 +26,13 @@ use futures::stream::StreamExt;
 use libp2p::core::{upgrade::Version, Multiaddr, Transport};
 use libp2p::identity::PeerId;
 use libp2p::metrics::{Metrics, Recorder};
-use libp2p::swarm::{keep_alive, NetworkBehaviour, SwarmBuilder, SwarmEvent};
+use libp2p::swarm::{NetworkBehaviour, SwarmBuilder, SwarmEvent};
 use libp2p::{identify, identity, noise, ping, tcp, yamux};
 use log::info;
 use prometheus_client::registry::Registry;
 use std::error::Error;
 use std::thread;
+use std::time::Duration;
 
 mod http_service;
 
@@ -51,6 +52,7 @@ fn main() -> Result<(), Box<dyn Error>> {
         Behaviour::new(local_pub_key),
         local_peer_id,
     )
+    .idle_connection_timeout(Duration::from_secs(60))
     .build();
 
     swarm.listen_on("/ip4/0.0.0.0/tcp/0".parse()?)?;
@@ -87,13 +89,9 @@ fn main() -> Result<(), Box<dyn Error>> {
 }
 
 /// Our network behaviour.
-///
-/// For illustrative purposes, this includes the [`keep_alive::Behaviour`]) behaviour so the ping actually happen
-/// and can be observed via the metrics.
 #[derive(NetworkBehaviour)]
 struct Behaviour {
     identify: identify::Behaviour,
-    keep_alive: keep_alive::Behaviour,
     ping: ping::Behaviour,
 }
 
@@ -105,7 +103,6 @@ impl Behaviour {
                 "/ipfs/0.1.0".into(),
                 local_pub_key,
             )),
-            keep_alive: keep_alive::Behaviour,
         }
     }
 }

examples/ping-example/src/main.rs

@@ -24,10 +24,11 @@ use futures::prelude::*;
 use libp2p::core::upgrade::Version;
 use libp2p::{
     identity, noise, ping,
-    swarm::{keep_alive, NetworkBehaviour, SwarmBuilder, SwarmEvent},
+    swarm::{SwarmBuilder, SwarmEvent},
     tcp, yamux, Multiaddr, PeerId, Transport,
 };
 use std::error::Error;
+use std::time::Duration;
 
 #[async_std::main]
 async fn main() -> Result<(), Box<dyn Error>> {
@@ -42,7 +43,8 @@ async fn main() -> Result<(), Box<dyn Error>> {
         .boxed();
 
     let mut swarm =
-        SwarmBuilder::with_async_std_executor(transport, Behaviour::default(), local_peer_id)
+        SwarmBuilder::with_async_std_executor(transport, ping::Behaviour::default(), local_peer_id)
+            .idle_connection_timeout(Duration::from_secs(60)) // For illustrative purposes, keep idle connections alive for a minute so we can observe a few pings.
             .build();
 
     // Tell the swarm to listen on all interfaces and a random, OS-assigned
@@ -65,13 +67,3 @@ async fn main() -> Result<(), Box<dyn Error>> {
         }
     }
 }
-
-/// Our network behaviour.
-///
-/// For illustrative purposes, this includes the [`KeepAlive`](keep_alive::Behaviour) behaviour so a continuous sequence of
-/// pings can be observed.
-#[derive(NetworkBehaviour, Default)]
-struct Behaviour {
-    keep_alive: keep_alive::Behaviour,
-    ping: ping::Behaviour,
-}

examples/rendezvous/src/bin/rzv-discover.rs

@@ -24,7 +24,7 @@ use libp2p::{
     identity,
     multiaddr::Protocol,
     noise, ping, rendezvous,
-    swarm::{keep_alive, NetworkBehaviour, SwarmBuilder, SwarmEvent},
+    swarm::{NetworkBehaviour, SwarmBuilder, SwarmEvent},
     tcp, yamux, Multiaddr, PeerId, Transport,
 };
 use std::time::Duration;
@@ -50,10 +50,10 @@ async fn main() {
         MyBehaviour {
             rendezvous: rendezvous::client::Behaviour::new(key_pair.clone()),
             ping: ping::Behaviour::new(ping::Config::new().with_interval(Duration::from_secs(1))),
-            keep_alive: keep_alive::Behaviour,
         },
         PeerId::from(key_pair.public()),
     )
+    .idle_connection_timeout(Duration::from_secs(5))
     .build();
 
     swarm.dial(rendezvous_point_address.clone()).unwrap();
@@ -127,5 +127,4 @@ async fn main() {
 struct MyBehaviour {
     rendezvous: rendezvous::client::Behaviour,
     ping: ping::Behaviour,
-    keep_alive: keep_alive::Behaviour,
 }

examples/rendezvous/src/bin/rzv-identify.rs

@@ -22,7 +22,7 @@ use futures::StreamExt;
 use libp2p::{
     core::transport::upgrade::Version,
     identify, identity, noise, ping, rendezvous,
-    swarm::{keep_alive, NetworkBehaviour, SwarmBuilder, SwarmEvent},
+    swarm::{NetworkBehaviour, SwarmBuilder, SwarmEvent},
     tcp, yamux, Multiaddr, PeerId, Transport,
 };
 use std::time::Duration;
@@ -50,10 +50,10 @@ async fn main() {
             )),
             rendezvous: rendezvous::client::Behaviour::new(key_pair.clone()),
             ping: ping::Behaviour::new(ping::Config::new().with_interval(Duration::from_secs(1))),
-            keep_alive: keep_alive::Behaviour,
         },
         PeerId::from(key_pair.public()),
     )
+    .idle_connection_timeout(Duration::from_secs(5))
     .build();
 
     let _ = swarm.listen_on("/ip4/0.0.0.0/tcp/0".parse().unwrap());
@@ -133,5 +133,4 @@ struct MyBehaviour {
     identify: identify::Behaviour,
     rendezvous: rendezvous::client::Behaviour,
     ping: ping::Behaviour,
-    keep_alive: keep_alive::Behaviour,
 }

examples/rendezvous/src/bin/rzv-register.rs

@@ -22,7 +22,7 @@ use futures::StreamExt;
 use libp2p::{
     core::transport::upgrade::Version,
     identity, noise, ping, rendezvous,
-    swarm::{keep_alive, NetworkBehaviour, SwarmBuilder, SwarmEvent},
+    swarm::{NetworkBehaviour, SwarmBuilder, SwarmEvent},
     tcp, yamux, Multiaddr, PeerId, Transport,
 };
 use std::time::Duration;
@@ -46,10 +46,10 @@ async fn main() {
         MyBehaviour {
             rendezvous: rendezvous::client::Behaviour::new(key_pair.clone()),
             ping: ping::Behaviour::new(ping::Config::new().with_interval(Duration::from_secs(1))),
-            keep_alive: keep_alive::Behaviour,
         },
         PeerId::from(key_pair.public()),
     )
+    .idle_connection_timeout(Duration::from_secs(5))
     .build();
 
     // In production the external address should be the publicly facing IP address of the rendezvous point.
@@ -130,5 +130,4 @@ async fn main() {
 struct MyBehaviour {
     rendezvous: rendezvous::client::Behaviour,
     ping: ping::Behaviour,
-    keep_alive: keep_alive::Behaviour,
 }

examples/rendezvous/src/main.rs

@@ -24,7 +24,7 @@ use futures::StreamExt;
 use libp2p::{
     core::transport::upgrade::Version,
     identify, identity, noise, ping, rendezvous,
-    swarm::{keep_alive, NetworkBehaviour, SwarmBuilder, SwarmEvent},
+    swarm::{NetworkBehaviour, SwarmBuilder, SwarmEvent},
     tcp, yamux, PeerId, Transport,
 };
 use std::time::Duration;
@@ -48,10 +48,10 @@ async fn main() {
             )),
             rendezvous: rendezvous::server::Behaviour::new(rendezvous::server::Config::default()),
             ping: ping::Behaviour::new(ping::Config::new().with_interval(Duration::from_secs(1))),
-            keep_alive: keep_alive::Behaviour,
         },
         PeerId::from(key_pair.public()),
     )
+    .idle_connection_timeout(Duration::from_secs(5))
     .build();
 
     let _ = swarm.listen_on("/ip4/0.0.0.0/tcp/62649".parse().unwrap());
@@ -97,5 +97,4 @@ struct MyBehaviour {
     identify: identify::Behaviour,
     rendezvous: rendezvous::server::Behaviour,
     ping: ping::Behaviour,
-    keep_alive: keep_alive::Behaviour,
 }

interop-tests/src/lib.rs

@@ -3,8 +3,8 @@ use std::time::Duration;
 
 use anyhow::{bail, Context, Result};
 use futures::{FutureExt, StreamExt};
-use libp2p::swarm::{keep_alive, NetworkBehaviour, SwarmEvent};
-use libp2p::{identify, identity, ping, Multiaddr, PeerId};
+use libp2p::swarm::SwarmEvent;
+use libp2p::{identify, identity, ping, swarm::NetworkBehaviour, Multiaddr, PeerId};
 #[cfg(target_arch = "wasm32")]
 use wasm_bindgen::prelude::*;
 
@@ -33,8 +33,7 @@ pub async fn run_test(
     let mut swarm = swarm_builder(
         boxed_transport,
         Behaviour {
-            ping: ping::Behaviour::new(ping::Config::new().with_interval(Duration::from_secs(1))),
-            keep_alive: keep_alive::Behaviour,
+            ping: ping::Behaviour::new(ping::Config::new().with_interval(Duration::from_secs(10))),
             // Need to include identify until https://github.com/status-im/nim-libp2p/issues/924 is resolved.
             identify: identify::Behaviour::new(identify::Config::new(
                 "/interop-tests".to_owned(),
@@ -43,6 +42,7 @@ pub async fn run_test(
         },
         local_peer_id,
     )
+    .idle_connection_timeout(Duration::from_secs(5))
     .build();
 
     log::info!("Running ping test: {}", swarm.local_peer_id());
@@ -242,7 +242,6 @@ impl FromStr for SecProtocol {
 #[derive(NetworkBehaviour)]
 struct Behaviour {
     ping: ping::Behaviour,
-    keep_alive: keep_alive::Behaviour,
     identify: identify::Behaviour,
 }