Fix connection & handler shutdown when using KeepAlive::Now. (#1072)

* Fix connection & handler shutdown when using `KeepAlive::Now`.

Delay::new(Instant::now()) is never immediately ready, resulting in
`KeepAlive::Now` to have no effect, since the delay is re-created on
every execution of `poll()` in the `NodeHandlerWrapper`. It can also
send the node handler into a busy-loop, since every newly
created Delay will trigger a task wakeup, which creates a new Delay
with Instant::now(), and so forth.

The use of `Delay::new(Instant::now())` for "immediate" connection shutdown
is therefore removed here entirely. An important assumption is thereby
that as long as the node handler non-empty `negotiating_in` and `negotiating_out`,
the handler is not dependent on such a Delay for task wakeup.

* Trigger CI.

core/src/protocols_handler/node_handler.rs

@@ -31,7 +31,7 @@ use crate::{
     }
 };
 use futures::prelude::*;
-use std::{error, fmt, time::{Duration, Instant}};
+use std::{error, fmt, time::Duration};
 use tokio_timer::{Delay, Timeout};
 
 /// Prototype for a `NodeHandlerWrapper`.
@@ -64,7 +64,7 @@ where
             negotiating_out: Vec::new(),
             queued_dial_upgrades: Vec::new(),
             unique_dial_upgrade_id: 0,
-            connection_shutdown: None,
+            shutdown: Shutdown::None,
         }
     }
 }
@@ -85,7 +85,7 @@ where
             negotiating_out: Vec::new(),
             queued_dial_upgrades: Vec::new(),
             unique_dial_upgrade_id: 0,
-            connection_shutdown: None,
+            shutdown: Shutdown::None,
         }
     }
 }
@@ -112,9 +112,26 @@ where
     queued_dial_upgrades: Vec<(u64, TProtoHandler::OutboundProtocol)>,
     /// Unique identifier assigned to each queued dial upgrade.
     unique_dial_upgrade_id: u64,
-    /// When a connection has been deemed useless, will contain `Some` with a `Delay` to when it
-    /// should be shut down.
-    connection_shutdown: Option<Delay>,
+    /// The currently planned connection & handler shutdown.
+    shutdown: Shutdown,
+}
+
+/// The options for a planned connection & handler shutdown.
+///
+/// A shutdown is planned anew based on the the return value of
+/// [`ProtocolsHandler::connection_keep_alive`] of the underlying handler
+/// after every invocation of [`ProtocolsHandler::poll`].
+///
+/// A planned shutdown is always postponed for as long as there are ingoing
+/// or outgoing substreams being negotiated, i.e. it is a graceful, "idle"
+/// shutdown.
+enum Shutdown {
+    /// No shutdown is planned.
+    None,
+    /// A shut down is planned as soon as possible.
+    Asap,
+    /// A shut down is planned for when a `Delay` has elapsed.
+    Later(Delay)
 }
 
 /// Error generated by the `NodeHandlerWrapper`.
@@ -257,10 +274,12 @@ where
         // calls on `self.handler`.
         let poll_result = self.handler.poll()?;
 
-        self.connection_shutdown = match self.handler.connection_keep_alive() {
-            KeepAlive::Until(expiration) => Some(Delay::new(expiration)),
-            KeepAlive::Now => Some(Delay::new(Instant::now())),
-            KeepAlive::Forever => None,
+        // Ask the handler whether it wants the connection (and the handler itself)
+        // to be kept alive, which determines the planned shutdown, if any.
+        self.shutdown = match self.handler.connection_keep_alive() {
+            KeepAlive::Until(t) => Shutdown::Later(Delay::new(t)),
+            KeepAlive::Now => Shutdown::Asap,
+            KeepAlive::Forever => Shutdown::None
         };
 
         match poll_result {
@@ -282,21 +301,18 @@ where
             Async::NotReady => (),
         };
 
-        // Check the `connection_shutdown`.
-        if let Some(mut connection_shutdown) = self.connection_shutdown.take() {
-            // If we're negotiating substreams, let's delay the closing.
+        // Check if the connection (and handler) should be shut down.
+        // As long as we're still negotiating substreams, shutdown is always postponed.
         if self.negotiating_in.is_empty() && self.negotiating_out.is_empty() {
-                match connection_shutdown.poll() {
-                    Ok(Async::Ready(_)) | Err(_) => {
-                        return Err(NodeHandlerWrapperError::UselessTimeout);
-                    },
-                    Ok(Async::NotReady) => {
-                        self.connection_shutdown = Some(connection_shutdown);
+            match self.shutdown {
+                Shutdown::None => {},
+                Shutdown::Asap => return Err(NodeHandlerWrapperError::UselessTimeout),
+                Shutdown::Later(ref mut delay) => match delay.poll() {
+                    Ok(Async::Ready(_)) | Err(_) =>
+                        return Err(NodeHandlerWrapperError::UselessTimeout),
+                    Ok(Async::NotReady) => {}
                 }
             }
-            } else {
-                self.connection_shutdown = Some(connection_shutdown);
-            }
         }
 
         Ok(Async::NotReady)

core/tests/raw_swarm_simult.rs

@@ -76,7 +76,7 @@ where
 
     }
 
-    fn connection_keep_alive(&self) -> KeepAlive { KeepAlive::Now }
+    fn connection_keep_alive(&self) -> KeepAlive { KeepAlive::Forever }
 
     fn poll(&mut self) -> Poll<ProtocolsHandlerEvent<Self::OutboundProtocol, Self::OutboundOpenInfo, Self::OutEvent>, Self::Error> {
         Ok(Async::NotReady)

protocols/identify/src/identify.rs

@@ -220,60 +220,60 @@ pub enum IdentifyEvent {
 #[cfg(test)]
 mod tests {
     use crate::{Identify, IdentifyEvent};
-    use futures::prelude::*;
-    use libp2p_core::identity;
+    use futures::{future, prelude::*};
     use libp2p_core::{
+        identity,
+        PeerId,
         upgrade::{self, OutboundUpgradeExt, InboundUpgradeExt},
+        muxing::StreamMuxer,
         Multiaddr,
         Swarm,
         Transport
     };
+    use libp2p_tcp::TcpConfig;
+    use libp2p_secio::SecioConfig;
+    use libp2p_mplex::MplexConfig;
     use rand::Rng;
-    use std::io;
+    use std::{fmt, io};
+    use tokio::runtime::current_thread;
+
+    fn transport() -> (identity::PublicKey, impl Transport<
+        Output = (PeerId, impl StreamMuxer<Substream = impl Send, OutboundSubstream = impl Send>),
+        Listener = impl Send,
+        ListenerUpgrade = impl Send,
+        Dial = impl Send,
+        Error = impl fmt::Debug
+    > + Clone) {
+        let id_keys = identity::Keypair::generate_ed25519();
+        let pubkey = id_keys.public();
+        let transport = TcpConfig::new()
+            .nodelay(true)
+            .with_upgrade(SecioConfig::new(id_keys))
+            .and_then(move |out, endpoint| {
+                let peer_id = out.remote_key.into_peer_id();
+                let peer_id2 = peer_id.clone();
+                let upgrade = MplexConfig::default()
+                    .map_outbound(move |muxer| (peer_id, muxer))
+                    .map_inbound(move |muxer| (peer_id2, muxer));
+                upgrade::apply(out.stream, upgrade, endpoint)
+            });
+        (pubkey, transport)
+    }
 
     #[test]
     fn periodic_id_works() {
-        let node1_key = identity::Keypair::generate_ed25519();
-        let node1_public_key = node1_key.public();
-        let node2_key = identity::Keypair::generate_ed25519();
-        let node2_public_key = node2_key.public();
-
-        let mut swarm1 = {
-            // TODO: make creating the transport more elegant ; literaly half of the code of the test
-            //       is about creating the transport
-            let local_peer_id = node1_public_key.clone().into_peer_id();
-            let transport = libp2p_tcp::TcpConfig::new()
-                .with_upgrade(libp2p_secio::SecioConfig::new(node1_key))
-                .and_then(move |out, endpoint| {
-                    let peer_id = out.remote_key.into_peer_id();
-                    let peer_id2 = peer_id.clone();
-                    let upgrade = libp2p_mplex::MplexConfig::default()
-                        .map_outbound(move |muxer| (peer_id, muxer))
-                        .map_inbound(move |muxer| (peer_id2, muxer));
-                    upgrade::apply(out.stream, upgrade, endpoint)
-                })
-                .map_err(|_| -> io::Error { panic!() });
-
-            Swarm::new(transport, Identify::new("a".to_string(), "b".to_string(), node1_public_key.clone()), local_peer_id)
+        let (mut swarm1, pubkey1) = {
+            let (pubkey, transport) = transport();
+            let protocol = Identify::new("a".to_string(), "b".to_string(), pubkey.clone());
+            let swarm = Swarm::new(transport, protocol, pubkey.clone().into_peer_id());
+            (swarm, pubkey)
         };
 
-        let mut swarm2 = {
-            // TODO: make creating the transport more elegant ; literaly half of the code of the test
-            //       is about creating the transport
-            let local_peer_id = node2_public_key.clone().into();
-            let transport = libp2p_tcp::TcpConfig::new()
-                .with_upgrade(libp2p_secio::SecioConfig::new(node2_key))
-                .and_then(move |out, endpoint| {
-                    let peer_id = out.remote_key.into_peer_id();
-                    let peer_id2 = peer_id.clone();
-                    let upgrade = libp2p_mplex::MplexConfig::default()
-                        .map_outbound(move |muxer| (peer_id, muxer))
-                        .map_inbound(move |muxer| (peer_id2, muxer));
-                    upgrade::apply(out.stream, upgrade, endpoint)
-                })
-                .map_err(|_| -> io::Error { panic!() });
-
-            Swarm::new(transport, Identify::new("c".to_string(), "d".to_string(), node2_public_key.clone()), local_peer_id)
+        let (mut swarm2, pubkey2) = {
+            let (pubkey, transport) = transport();
+            let protocol = Identify::new("c".to_string(), "d".to_string(), pubkey.clone());
+            let swarm = Swarm::new(transport, protocol, pubkey.clone().into_peer_id());
+            (swarm, pubkey)
         };
 
         let addr: Multiaddr = {
@@ -282,51 +282,45 @@ mod tests {
         };
 
         Swarm::listen_on(&mut swarm1, addr.clone()).unwrap();
-        Swarm::dial_addr(&mut swarm2, addr).unwrap();
+        Swarm::dial_addr(&mut swarm2, addr.clone()).unwrap();
 
-        let mut swarm1_good = false;
-        let mut swarm2_good = false;
-
-        tokio::runtime::current_thread::Runtime::new()
-            .unwrap()
-            .block_on(futures::future::poll_fn(move || -> Result<_, io::Error> {
+        // nb. Either swarm may receive the `Identified` event first, upon which
+        // it will permit the connection to be closed, as defined by
+        // `PeriodicIdHandler::connection_keep_alive`. Hence the test succeeds if
+        // either `Identified` event arrives correctly.
+        current_thread::Runtime::new().unwrap().block_on(
+            future::poll_fn(move || -> Result<_, io::Error> {
                 loop {
-                    let mut swarm1_not_ready = false;
                     match swarm1.poll().unwrap() {
                         Async::Ready(Some(IdentifyEvent::Identified { info, .. })) => {
-                            assert_eq!(info.public_key, node2_public_key);
+                            assert_eq!(info.public_key, pubkey2);
                             assert_eq!(info.protocol_version, "c");
                             assert_eq!(info.agent_version, "d");
                             assert!(!info.protocols.is_empty());
                             assert!(info.listen_addrs.is_empty());
-                            swarm1_good = true;
+                            return Ok(Async::Ready(()))
                         },
                         Async::Ready(Some(IdentifyEvent::SendBack { result: Ok(()), .. })) => (),
-                        Async::Ready(_) => panic!(),
-                        Async::NotReady => swarm1_not_ready = true,
+                        Async::Ready(e) => panic!("{:?}", e),
+                        Async::NotReady => {}
                     }
 
                     match swarm2.poll().unwrap() {
                         Async::Ready(Some(IdentifyEvent::Identified { info, .. })) => {
-                            assert_eq!(info.public_key, node1_public_key);
+                            assert_eq!(info.public_key, pubkey1);
                             assert_eq!(info.protocol_version, "a");
                             assert_eq!(info.agent_version, "b");
                             assert!(!info.protocols.is_empty());
                             assert_eq!(info.listen_addrs.len(), 1);
-                            swarm2_good = true;
+                            return Ok(Async::Ready(()))
                         },
                         Async::Ready(Some(IdentifyEvent::SendBack { result: Ok(()), .. })) => (),
-                        Async::Ready(_) => panic!(),
-                        Async::NotReady if swarm1_not_ready => break,
-                        Async::NotReady => ()
+                        Async::Ready(e) => panic!("{:?}", e),
+                        Async::NotReady => break
                     }
                 }
 
-                if swarm1_good && swarm2_good {
-                    Ok(Async::Ready(()))
-                } else {
                 Ok(Async::NotReady)
-                }
             }))
             .unwrap();
     }