support resume_gateway_url

Docs PR: discord/discord-api-docs#5282

twilight-gateway/src/compression/inflater.rs

@@ -6,7 +6,7 @@
 //!
 //! # Resizing buffers
 //!
-//! Buffers are resized after some heurestics:
+//! Buffers are resized after some heuristics:
 //!
 //! - if the data does not fit the buffer size is doubled; or
 //! - at most once per minute the buffer will be resized down to the size of the
@@ -34,7 +34,7 @@ const INTERNAL_BUFFER_SIZE: usize = 32 * 1024;
 #[derive(Debug)]
 pub struct Inflater {
     /// Zlib decompressor, which can have a considerable heap size given the
-    /// main way this saves memory is by having a directonary to look up data.
+    /// main way this saves memory is by having a dictionary to look up data.
     decompress: Decompress,
     /// Buffer for storing compressed data. Data is stored here via [`extend`].
     ///

twilight-gateway/src/config.rs

@@ -294,6 +294,11 @@ impl ConfigBuilder {
     }
 
     /// Set the proxy URL for connecting to the gateway.
+    ///
+    /// When reconnecting, the shard will always use this URL instead of
+    /// [`resume_gateway_url`]. Proper reconnection is left to the proxy.
+    ///
+    /// [`resume_gateway_url`]: twilight_model::gateway::payload::incoming::Ready::resume_gateway_url
     #[allow(clippy::missing_const_for_fn)]
     pub fn gateway_url(mut self, gateway_url: String) -> Self {
         self.inner.gateway_url = Some(gateway_url);

twilight-gateway/src/shard.rs

@@ -40,12 +40,19 @@
 //! then the previous steps are taken and the resultant message is deserialized
 //! into a [`GatewayEvent`].
 //!
+//! # Reconnecting
+//!
+//! If a custom gateway URL is used when reconnecting, the shard will always
+//! prefer it over the [`resume_gateway_url`]. Proper reconnection is left to
+//! the proxy.
+//!
+//! [`GatewayEvent`]: twilight_model::gateway::event::GatewayEvent
+//! [`resume_gateway_url`]: twilight_model::gateway::payload::incoming::Ready::resume_gateway_url
 //! [command]: crate::Command
 //! [is enabled]: Config::ratelimit_messages
 //! [processed]: Shard::process
-//! [websocket message]: crate::message::Message
 //! [websocket connection]: Shard::connection
-//! [`GatewayEvent`]: twilight_model::gateway::event::GatewayEvent
+//! [websocket message]: crate::message::Message
 
 use crate::{
     channel::{MessageChannel, MessageSender},
@@ -122,7 +129,7 @@ pub enum ConnectionStatus {
     /// Shard has fatally closed.
     ///
     /// Possible reasons may be due to [failed authentication],
-    /// [invalid intents], or other reasons. Refer to the documtation for
+    /// [invalid intents], or other reasons. Refer to the documentation for
     /// [`CloseCode`] for possible reasons.
     ///
     /// [failed authentication]: CloseCode::AuthenticationFailed
@@ -197,6 +204,8 @@ struct MinimalEvent<T> {
 /// [`Ready`]: twilight_model::gateway::payload::incoming::Ready
 #[derive(Deserialize)]
 struct MinimalReady {
+    /// Used for resuming connections.
+    resume_gateway_url: String,
     /// ID of the new identified session.
     session_id: String,
 }
@@ -305,6 +314,8 @@ pub struct Shard {
     /// Command ratelimiter, if it was enabled via
     /// [`Config::ratelimit_messages`].
     ratelimiter: Option<CommandRatelimiter>,
+    /// Used for resuming connections.
+    resume_gateway_url: Option<String>,
     /// Active session of the shard.
     ///
     /// The shard may not have an active session if it hasn't completed a full
@@ -394,6 +405,7 @@ impl Shard {
             id: shard_id,
             latency: Latency::new(),
             ratelimiter: None,
+            resume_gateway_url: None,
             session,
             status: ConnectionStatus::Connected,
             user_channel: MessageChannel::new(),
@@ -840,6 +852,7 @@ impl Shard {
                     source: None,
                 })?;
 
+                self.resume_gateway_url = Some(event.data.resume_gateway_url);
                 self.status = ConnectionStatus::Connected;
                 self.session = Some(Session::new(sequence, event.data.session_id));
             }
@@ -894,17 +907,21 @@ impl Shard {
     ) -> Result<(), ReceiveMessageError> {
         future::reconnect_delay(reconnect_attempts).await;
 
-        self.connection =
-            connection::connect(self.id(), self.config.gateway_url(), self.config.tls())
-                .await
-                .map_err(|source| {
-                    self.status = ConnectionStatus::Disconnected {
-                        close_code,
-                        reconnect_attempts: reconnect_attempts + 1,
-                    };
+        let maybe_gateway_url = self
+            .config
+            .gateway_url()
+            .or(self.resume_gateway_url.as_deref());
 
-                    ReceiveMessageError::from_reconnect(source)
-                })?;
+        self.connection = connection::connect(self.id(), maybe_gateway_url, self.config.tls())
+            .await
+            .map_err(|source| {
+                self.status = ConnectionStatus::Disconnected {
+                    close_code,
+                    reconnect_attempts: reconnect_attempts + 1,
+                };
+
+                ReceiveMessageError::from_reconnect(source)
+            })?;
         self.compression.reset();
         self.status = ConnectionStatus::Connected;
 

twilight-model/src/gateway/payload/incoming/ready.rs

@@ -5,6 +5,7 @@ use serde::{Deserialize, Serialize};
 pub struct Ready {
     pub application: PartialApplication,
     pub guilds: Vec<UnavailableGuild>,
+    pub resume_gateway_url: String,
     pub session_id: String,
     #[serde(skip_serializing_if = "Option::is_none")]
     pub shard: Option<[u64; 2]>,
@@ -44,6 +45,7 @@ mod tests {
                 id: Id::new(100),
             },
             guilds,
+            resume_gateway_url: "wss://gateway.discord.gg".into(),
             session_id: "foo".to_owned(),
             shard: Some([4, 7]),
             user: CurrentUser {
@@ -106,6 +108,8 @@ mod tests {
                 Token::Bool(true),
                 Token::StructEnd,
                 Token::SeqEnd,
+                Token::Str("resume_gateway_url"),
+                Token::Str("wss://gateway.discord.gg"),
                 Token::Str("session_id"),
                 Token::Str("foo"),
                 Token::Str("shard"),

twilight-standby/src/lib.rs

@@ -1324,6 +1324,7 @@ mod tests {
                 id: Id::new(1),
             },
             guilds: Vec::new(),
+            resume_gateway_url: "wss://gateway.discord.gg".into(),
             session_id: String::new(),
             shard: Some([5, 7]),
             user: CurrentUser {