Gateway: Add connection timeout, add Config to gateway. (#51)

This change fixes tasks hanging due to rare cases of messages being lost between full Discord reconnections by placing a configurable timeout on the `ConnectionInfo` responses. This is a companion fix to [serenity#1255](https://github.com/serenity-rs/serenity/pull/1255). To make this doable, `Config`s are now used by all versions of `Songbird`/`Call`, and relevant functions are  added to simplify setup with configuration. These are now non-exhaustive, correcting an earlier oversight. For future extensibility, this PR moves the return type of `join`/`join_gateway` into a custom future (no longer leaking flume's `RecvFut` type).

Additionally, this fixes the Makefile's feature sets for driver/gateway-only compilation.

This is a breaking change in:
* the return types of `join`/`join_gateway`
* moving `crate::driver::Config` -> `crate::Config`,
* `Config` and `JoinError` becoming `#[non_breaking]`.

This was tested via `cargo make ready`, and by testing `examples/serenity/voice_receive` with various timeout settings.

src/driver/config.rs

@@ -1,81 +0,0 @@
-use super::{CryptoMode, DecodeMode};
-
-/// Configuration for the inner Driver.
-///
-#[derive(Clone, Debug)]
-pub struct Config {
-    /// Selected tagging mode for voice packet encryption.
-    ///
-    /// Defaults to [`CryptoMode::Normal`].
-    ///
-    /// Changes to this field will not immediately apply if the
-    /// driver is actively connected, but will apply to subsequent
-    /// sessions.
-    ///
-    /// [`CryptoMode::Normal`]: CryptoMode::Normal
-    pub crypto_mode: CryptoMode,
-    /// Configures whether decoding and decryption occur for all received packets.
-    ///
-    /// If voice receiving voice packets, generally you should choose [`DecodeMode::Decode`].
-    /// [`DecodeMode::Decrypt`] is intended for users running their own selective decoding,
-    /// who rely upon [user speaking events], or who need to inspect Opus packets.
-    /// If you're certain you will never need any RT(C)P events, then consider [`DecodeMode::Pass`].
-    ///
-    /// Defaults to [`DecodeMode::Decrypt`]. This is due to per-packet decoding costs,
-    /// which most users will not want to pay, but allowing speaking events which are commonly used.
-    ///
-    /// [`DecodeMode::Decode`]: DecodeMode::Decode
-    /// [`DecodeMode::Decrypt`]: DecodeMode::Decrypt
-    /// [`DecodeMode::Pass`]: DecodeMode::Pass
-    /// [user speaking events]: crate::events::CoreEvent::SpeakingUpdate
-    pub decode_mode: DecodeMode,
-    /// Number of concurrently active tracks to allocate memory for.
-    ///
-    /// This should be set at, or just above, the maximum number of tracks
-    /// you expect your bot will play at the same time. Exceeding the size of
-    /// the internal queue will trigger a larger memory allocation and copy,
-    /// possibly causing the mixer thread to miss a packet deadline.
-    ///
-    /// Defaults to `1`.
-    ///
-    /// Changes to this field in a running driver will only ever increase
-    /// the capacity of the track store.
-    pub preallocated_tracks: usize,
-}
-
-impl Default for Config {
-    fn default() -> Self {
-        Self {
-            crypto_mode: CryptoMode::Normal,
-            decode_mode: DecodeMode::Decrypt,
-            preallocated_tracks: 1,
-        }
-    }
-}
-
-impl Config {
-    /// Sets this `Config`'s chosen cryptographic tagging scheme.
-    pub fn crypto_mode(mut self, crypto_mode: CryptoMode) -> Self {
-        self.crypto_mode = crypto_mode;
-        self
-    }
-
-    /// Sets this `Config`'s received packet decryption/decoding behaviour.
-    pub fn decode_mode(mut self, decode_mode: DecodeMode) -> Self {
-        self.decode_mode = decode_mode;
-        self
-    }
-
-    /// Sets this `Config`'s number of tracks to preallocate.
-    pub fn preallocated_tracks(mut self, preallocated_tracks: usize) -> Self {
-        self.preallocated_tracks = preallocated_tracks;
-        self
-    }
-
-    /// This is used to prevent changes which would invalidate the current session.
-    pub(crate) fn make_safe(&mut self, previous: &Config, connected: bool) {
-        if connected {
-            self.crypto_mode = previous.crypto_mode;
-        }
-    }
-}

src/driver/mod.rs

@@ -11,13 +11,11 @@
 #[cfg(feature = "internals")]
 pub mod bench_internals;
 
-mod config;
 pub(crate) mod connection;
 mod crypto;
 mod decode_mode;
 pub(crate) mod tasks;
 
-pub use config::Config;
 use connection::error::{Error, Result};
 pub use crypto::CryptoMode;
 pub(crate) use crypto::CryptoState;
@@ -29,6 +27,7 @@ use crate::{
     events::EventData,
     input::Input,
     tracks::{self, Track, TrackHandle},
+    Config,
     ConnectionInfo,
     Event,
     EventHandler,
@@ -212,13 +211,19 @@ impl Driver {
         self.send(CoreMessage::SetTrack(None))
     }
 
-    /// Sets the configuration for this driver.
+    /// Sets the configuration for this driver (and parent `Call`, if applicable).
     #[instrument(skip(self))]
     pub fn set_config(&mut self, config: Config) {
         self.config = config.clone();
         self.send(CoreMessage::SetConfig(config))
     }
 
+    /// Returns a view of this driver's configuration.
+    #[instrument(skip(self))]
+    pub fn config(&self) -> &Config {
+        &self.config
+    }
+
     /// Attach a global event handler to an audio context. Global events may receive
     /// any [`EventContext`].
     ///

src/driver/tasks/error.rs

@@ -17,6 +17,7 @@ pub enum Recipient {
 pub type Result<T> = std::result::Result<T, Error>;
 
 #[derive(Debug)]
+#[non_exhaustive]
 pub enum Error {
     Crypto(CryptoError),
     /// Received an illegal voice packet on the voice UDP socket.

src/driver/tasks/mixer.rs

@@ -1,7 +1,8 @@
-use super::{disposal, error::Result, message::*, Config};
+use super::{disposal, error::Result, message::*};
 use crate::{
     constants::*,
     tracks::{PlayMode, Track},
+    Config,
 };
 use audiopus::{
     coder::Encoder as OpusEncoder,

src/driver/tasks/mod.rs

@@ -9,11 +9,8 @@ pub(crate) mod udp_rx;
 pub(crate) mod udp_tx;
 pub(crate) mod ws;
 
-use super::{
-    connection::{error::Error as ConnectionError, Connection},
-    Config,
-};
-use crate::events::CoreContext;
+use super::connection::{error::Error as ConnectionError, Connection};
+use crate::{events::CoreContext, Config};
 use flume::{Receiver, RecvError, Sender};
 use message::*;
 #[cfg(not(feature = "tokio-02-marker"))]

src/driver/tasks/udp_rx.rs

@@ -1,12 +1,9 @@
 use super::{
     error::{Error, Result},
     message::*,
+    Config,
 };
-use crate::{
-    constants::*,
-    driver::{Config, DecodeMode},
-    events::CoreContext,
-};
+use crate::{constants::*, driver::DecodeMode, events::CoreContext};
 use audiopus::{
     coder::Decoder as OpusDecoder,
     error::{Error as OpusError, ErrorCode},