Enable sending Continuations from actix-ws (#431)

* Enable sending continuations from an actix-ws Session

* actix-ws: Allow sending continuations from Session

* Convert ignored doctests to no_run doctests

---------

Co-authored-by: Rob Ede <robjtede@icloud.com>

actix-ws/CHANGELOG.md

@@ -4,6 +4,7 @@
 
 - Remove type parameters from `Session::{text, binary}()` methods, replacing with equivalent `impl Trait` parameters.
 - `Session::text()` now receives an `impl Into<ByteString>`, making broadcasting text messages more efficient.
+- Allow sending continuations via `Session::continuation()`
 
 ## 0.2.5
 

actix-ws/src/fut.rs

@@ -65,10 +65,13 @@ impl MessageStream {
 
     /// Wait for the next item from the message stream
     ///
-    /// ```rust,ignore
+    /// ```rust,no_run
+    /// # use actix_ws::MessageStream;
+    /// # async fn test(mut stream: MessageStream) {
     /// while let Some(Ok(msg)) = stream.recv().await {
     ///     // handle message
     /// }
+    /// # }
     /// ```
     pub async fn recv(&mut self) -> Option<Result<Message, ProtocolError>> {
         poll_fn(|cx| Pin::new(&mut *self).poll_next(cx)).await

actix-ws/src/lib.rs

@@ -8,7 +8,7 @@
 #![doc(html_favicon_url = "https://actix.rs/favicon.ico")]
 #![cfg_attr(docsrs, feature(doc_auto_cfg))]
 
-pub use actix_http::ws::{CloseCode, CloseReason, Message, ProtocolError};
+pub use actix_http::ws::{CloseCode, CloseReason, Item, Message, ProtocolError};
 use actix_http::{
     body::{BodyStream, MessageBody},
     ws::handshake,

actix-ws/src/session.rs

@@ -3,7 +3,7 @@ use std::sync::{
     Arc,
 };
 
-use actix_http::ws::{CloseReason, Message};
+use actix_http::ws::{CloseReason, Item, Message};
 use actix_web::web::Bytes;
 use bytestring::ByteString;
 use tokio::sync::mpsc::Sender;
@@ -45,10 +45,13 @@ impl Session {
 
     /// Send text into the websocket
     ///
-    /// ```rust,ignore
+    /// ```rust,no_run
+    /// # use actix_ws::Session;
+    /// # async fn test(mut session: Session) {
     /// if session.text("Some text").await.is_err() {
     ///     // session closed
     /// }
+    /// # }
     /// ```
     pub async fn text(&mut self, msg: impl Into<ByteString>) -> Result<(), Closed> {
         self.pre_check();
@@ -64,10 +67,13 @@ impl Session {
 
     /// Send raw bytes into the websocket
     ///
-    /// ```rust,ignore
-    /// if session.binary(b"some bytes").await.is_err() {
+    /// ```rust,no_run
+    /// # use actix_ws::Session;
+    /// # async fn test(mut session: Session) {
+    /// if session.binary(&b"some bytes"[..]).await.is_err() {
     ///     // session closed
     /// }
+    /// # }
     /// ```
     pub async fn binary(&mut self, msg: impl Into<Bytes>) -> Result<(), Closed> {
         self.pre_check();
@@ -86,10 +92,13 @@ impl Session {
     /// For many applications, it will be important to send regular pings to keep track of if the
     /// client has disconnected
     ///
-    /// ```rust,ignore
+    /// ```rust,no_run
+    /// # use actix_ws::Session;
+    /// # async fn test(mut session: Session) {
     /// if session.ping(b"").await.is_err() {
     ///     // session is closed
     /// }
+    /// # }
     /// ```
     pub async fn ping(&mut self, msg: &[u8]) -> Result<(), Closed> {
         self.pre_check();
@@ -105,13 +114,16 @@ impl Session {
 
     /// Pong the client
     ///
-    /// ```rust,ignore
+    /// ```rust,no_run
+    /// # use actix_ws::{Message, Session};
+    /// # async fn test(mut session: Session, msg: Message) {
     /// match msg {
     ///     Message::Ping(bytes) => {
     ///         let _ = session.pong(&bytes).await;
     ///     }
     ///     _ => (),
     /// }
+    /// # }
     pub async fn pong(&mut self, msg: &[u8]) -> Result<(), Closed> {
         self.pre_check();
         if let Some(inner) = self.inner.as_mut() {
@@ -124,12 +136,47 @@ impl Session {
         }
     }
 
+    /// Manually control sending continuations
+    ///
+    /// Be wary of this method. Continuations represent multiple frames that, when combined, are
+    /// presented as a single message. They are useful when the entire contents of a message are
+    /// not avilable all at once. However, continuations MUST NOT be interrupted by other Text or
+    /// Binary messages. Control messages such as Ping, Pong, or Close are allowed to interrupt a
+    /// continuation.
+    ///
+    /// Continuations must be initialized with a First variant, and must be terminated by a Last
+    /// variant, with only Continue variants sent in between.
+    ///
+    /// ```rust,no_run
+    /// # use actix_ws::{Item, Session};
+    /// # async fn test(mut session: Session) -> Result<(), Box<dyn std::error::Error>> {
+    /// session.continuation(Item::FirstText("Hello".into())).await?;
+    /// session.continuation(Item::Continue(b", World"[..].into())).await?;
+    /// session.continuation(Item::Last(b"!"[..].into())).await?;
+    /// # Ok(())
+    /// # }
+    /// ```
+    pub async fn continuation(&mut self, msg: Item) -> Result<(), Closed> {
+        self.pre_check();
+        if let Some(inner) = self.inner.as_mut() {
+            inner
+                .send(Message::Continuation(msg))
+                .await
+                .map_err(|_| Closed)
+        } else {
+            Err(Closed)
+        }
+    }
+
     /// Send a close message, and consume the session
     ///
     /// All clones will return `Err(Closed)` if used after this call
     ///
-    /// ```rust,ignore
+    /// ```rust,no_run
+    /// # use actix_ws::{Closed, Session};
+    /// # async fn test(mut session: Session) -> Result<(), Closed> {
     /// session.close(None).await
+    /// # }
     /// ```
     pub async fn close(mut self, reason: Option<CloseReason>) -> Result<(), Closed> {
         self.pre_check();