Update tokio-tungstenite 0.20

Deprecate WebSocketUpgrade::max_send_queue
Add WebSocketUpgrade::write_buffer_size, max_write_buffer_size

axum/Cargo.toml

@@ -61,7 +61,7 @@ serde_path_to_error = { version = "0.1.8", optional = true }
 serde_urlencoded = { version = "0.7", optional = true }
 sha1 = { version = "0.10", optional = true }
 tokio = { package = "tokio", version = "1.25.0", features = ["time"], optional = true }
-tokio-tungstenite = { version = "0.19", optional = true }
+tokio-tungstenite = { version = "0.20", optional = true }
 tracing = { version = "0.1", default-features = false, optional = true }
 
 [dependencies.tower-http]

axum/src/extract/ws.rs

@@ -157,9 +157,37 @@ impl<F> std::fmt::Debug for WebSocketUpgrade<F> {
 }
 
 impl<F> WebSocketUpgrade<F> {
-    /// Set the size of the internal message send queue.
-    pub fn max_send_queue(mut self, max: usize) -> Self {
-        self.config.max_send_queue = Some(max);
+    /// Does nothing, instead use `max_write_buffer_size`.
+    #[deprecated]
+    pub fn max_send_queue(self, _: usize) -> Self {
+        self
+    }
+
+    /// The target minimum size of the write buffer to reach before writing the data
+    /// to the underlying stream.
+    /// The default value is 128 KiB.
+    ///
+    /// If set to `0` each message will be eagerly written to the underlying stream.
+    /// It is often more optimal to allow them to buffer a little, hence the default value.
+    ///
+    /// Note: [`flush`](SinkExt::flush) will always fully write the buffer regardless.
+    pub fn write_buffer_size(mut self, size: usize) -> Self {
+        self.config.write_buffer_size = size;
+        self
+    }
+
+    /// The max size of the write buffer in bytes. Setting this can provide backpressure
+    /// in the case the write buffer is filling up due to write errors.
+    /// The default value is unlimited.
+    ///
+    /// Note: The write buffer only builds up past [`write_buffer_size`](Self::write_buffer_size)
+    /// when writes to the underlying stream are failing. So the **write buffer can not
+    /// fill up if you are not observing write errors even if not flushing**.
+    ///
+    /// Note: Should always be at least [`write_buffer_size + 1 message`](Self::write_buffer_size)
+    /// and probably a little more depending on error handling strategy.
+    pub fn max_write_buffer_size(mut self, max: usize) -> Self {
+        self.config.max_write_buffer_size = max;
         self
     }
 

examples/testing-websockets/Cargo.toml

@@ -9,4 +9,4 @@ axum = { path = "../../axum", features = ["ws"] }
 futures = "0.3"
 hyper = { version = "0.14", features = ["full"] }
 tokio = { version = "1.0", features = ["full"] }
-tokio-tungstenite = "0.19"
+tokio-tungstenite = "0.20"

examples/websockets/Cargo.toml

@@ -10,7 +10,7 @@ futures = "0.3"
 futures-util = { version = "0.3", default-features = false, features = ["sink", "std"] }
 headers = "0.3"
 tokio = { version = "1.0", features = ["full"] }
-tokio-tungstenite = "0.19"
+tokio-tungstenite = "0.20"
 tower = { version = "0.4", features = ["util"] }
 tower-http = { version = "0.4.0", features = ["fs", "trace"] }
 tracing = "0.1"