Driver: Automate (re)connection logic (#81)

This PR adds several enhancements to Driver connection logic:
* Driver (re)connection attempts now have a default timeout of around 10s.
* The driver will now attempt to retry full connection attempts using a user-provided strategy: currently, this defaults to 5 attempts under an exponential backoff strategy.
* The driver will now fire `DriverDisconnect` events at the end of any session -- this unifies (re)connection failure events with session expiry as seen in #76, which should provide users with enough detail to know *which* voice channel to reconnect to. Users still need to be careful to read the session/channel IDs to ensure that they aren't overwriting another join.

This has been tested using `cargo make ready`, and by setting low timeouts to force failures in the voice receive example (with some additional error handlers).

Closes #68.

src/driver/connection/mod.rs

@@ -21,9 +21,9 @@ use error::{Error, Result};
 use flume::Sender;
 use std::{net::IpAddr, str::FromStr, sync::Arc};
 #[cfg(not(feature = "tokio-02-marker"))]
-use tokio::{net::UdpSocket, spawn};
+use tokio::{net::UdpSocket, spawn, time::timeout};
 #[cfg(feature = "tokio-02-marker")]
-use tokio_compat::{net::UdpSocket, spawn};
+use tokio_compat::{net::UdpSocket, spawn, time::timeout};
 use tracing::{debug, info, instrument};
 use url::Url;
 use xsalsa20poly1305::{aead::NewAead, XSalsa20Poly1305 as Cipher};
@@ -42,9 +42,23 @@ pub(crate) struct Connection {
 
 impl Connection {
     pub(crate) async fn new(
+        info: ConnectionInfo,
+        interconnect: &Interconnect,
+        config: &Config,
+        idx: usize,
+    ) -> Result<Connection> {
+        if let Some(t) = config.driver_timeout {
+            timeout(t, Connection::new_inner(info, interconnect, config, idx)).await?
+        } else {
+            Connection::new_inner(info, interconnect, config, idx).await
+        }
+    }
+
+    pub(crate) async fn new_inner(
         mut info: ConnectionInfo,
         interconnect: &Interconnect,
         config: &Config,
+        idx: usize,
     ) -> Result<Connection> {
         let url = generate_url(&mut info.endpoint)?;
 
@@ -207,6 +221,8 @@ impl Connection {
             client,
             ssrc,
             hello.heartbeat_interval,
+            idx,
+            info.clone(),
         ));
 
         spawn(udp_rx::runner(
@@ -226,7 +242,16 @@ impl Connection {
     }
 
     #[instrument(skip(self))]
-    pub async fn reconnect(&mut self) -> Result<()> {
+    pub async fn reconnect(&mut self, config: &Config) -> Result<()> {
+        if let Some(t) = config.driver_timeout {
+            timeout(t, self.reconnect_inner()).await?
+        } else {
+            self.reconnect_inner().await
+        }
+    }
+
+    #[instrument(skip(self))]
+    pub async fn reconnect_inner(&mut self) -> Result<()> {
         let url = generate_url(&mut self.info.endpoint)?;
 
         // Thread may have died, we want to send to prompt a clean exit