Merge pull request #357 from alexheretic/flush-writes-less

Rework to remove implicit flushes

.gitignore

@@ -1,2 +1,3 @@
 target
 Cargo.lock
+.vscode

CHANGELOG.md

@@ -1,3 +1,18 @@
+# Unreleased (0.20.0)
+- Remove many implicit flushing behaviours. In general reading and writing messages will no 
+  longer flush until calling `flush`. An exception is automatic responses (e.g. pongs) 
+  which will continue to be written and flushed when reading and writing.
+  This allows writing a batch of messages and flushing once.
+- Add `WebSocket::read`, `write`, `send`, `flush`. Deprecate `read_message`, `write_message`, `write_pending`.
+- Add `FrameSocket::read`, `write`, `send`, `flush`. Remove `read_frame`, `write_frame`, `write_pending`. 
+  Note: Previous use of `write_frame` may be replaced with `send`.
+- Add `WebSocketContext::read`, `write`, `flush`. Remove `read_message`, `write_message`, `write_pending`.
+  Note: Previous use of `write_message` may be replaced with `write` + `flush`.
+- Remove `send_queue`, replaced with using the frame write buffer to achieve similar results.
+  * Add `WebSocketConfig::max_write_buffer_size`. Deprecate `max_send_queue`.
+  * Add `Error::WriteBufferFull`. Remove `Error::SendQueueFull`.
+    Note: `WriteBufferFull` returns the message that could not be written as a `Message::Frame`.
+
 # 0.19.0
 
 - Update TLS dependencies.

Cargo.toml

@@ -67,6 +67,10 @@ rand = "0.8.4"
 name = "buffer"
 harness = false
 
+[[bench]]
+name = "write"
+harness = false
+
 [[example]]
 name = "client"
 required-features = ["handshake"]

README.md

@@ -14,11 +14,11 @@ fn main () {
         spawn (move || {
             let mut websocket = accept(stream.unwrap()).unwrap();
             loop {
-                let msg = websocket.read_message().unwrap();
+                let msg = websocket.read().unwrap();
 
                 // We do not want to send back ping/pong messages.
                 if msg.is_binary() || msg.is_text() {
-                    websocket.write_message(msg).unwrap();
+                    websocket.send(msg).unwrap();
                 }
             }
         });

benches/write.rs

@@ -0,0 +1,67 @@
+//! Benchmarks for write performance.
+use criterion::{BatchSize, Criterion};
+use std::{
+    hint,
+    io::{self, Read, Write},
+    time::{Duration, Instant},
+};
+use tungstenite::{Message, WebSocket};
+
+const MOCK_WRITE_LEN: usize = 8 * 1024 * 1024;
+
+/// `Write` impl that simulates fast writes and slow flushes.
+///
+/// Buffers up to 8 MiB fast on `write`. Each `flush` takes ~100ns.
+struct MockSlowFlushWrite(Vec<u8>);
+
+impl Read for MockSlowFlushWrite {
+    fn read(&mut self, _: &mut [u8]) -> io::Result<usize> {
+        Err(io::Error::new(io::ErrorKind::WouldBlock, "reads not supported"))
+    }
+}
+impl Write for MockSlowFlushWrite {
+    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
+        if self.0.len() + buf.len() > MOCK_WRITE_LEN {
+            self.flush()?;
+        }
+        self.0.extend(buf);
+        Ok(buf.len())
+    }
+
+    fn flush(&mut self) -> io::Result<()> {
+        if !self.0.is_empty() {
+            // simulate 100ns io
+            let a = Instant::now();
+            while a.elapsed() < Duration::from_nanos(100) {
+                hint::spin_loop();
+            }
+            self.0.clear();
+        }
+        Ok(())
+    }
+}
+
+fn benchmark(c: &mut Criterion) {
+    // Writes 100k small json text messages then flushes
+    c.bench_function("write 100k small texts then flush", |b| {
+        let mut ws = WebSocket::from_raw_socket(
+            MockSlowFlushWrite(Vec::with_capacity(MOCK_WRITE_LEN)),
+            tungstenite::protocol::Role::Server,
+            None,
+        );
+
+        b.iter_batched(
+            || (0..100_000).map(|i| Message::Text(format!("{{\"id\":{i}}}"))),
+            |batch| {
+                for msg in batch {
+                    ws.write(msg).unwrap();
+                }
+                ws.flush().unwrap();
+            },
+            BatchSize::SmallInput,
+        )
+    });
+}
+
+criterion::criterion_group!(write_benches, benchmark);
+criterion::criterion_main!(write_benches);

examples/autobahn-client.rs

@@ -7,7 +7,7 @@ const AGENT: &str = "Tungstenite";
 
 fn get_case_count() -> Result<u32> {
     let (mut socket, _) = connect(Url::parse("ws://localhost:9001/getCaseCount").unwrap())?;
-    let msg = socket.read_message()?;
+    let msg = socket.read()?;
     socket.close(None)?;
     Ok(msg.into_text()?.parse::<u32>().unwrap())
 }
@@ -26,9 +26,9 @@ fn run_test(case: u32) -> Result<()> {
         Url::parse(&format!("ws://localhost:9001/runCase?case={}&agent={}", case, AGENT)).unwrap();
     let (mut socket, _) = connect(case_url)?;
     loop {
-        match socket.read_message()? {
+        match socket.read()? {
             msg @ Message::Text(_) | msg @ Message::Binary(_) => {
-                socket.write_message(msg)?;
+                socket.send(msg)?;
             }
             Message::Ping(_) | Message::Pong(_) | Message::Close(_) | Message::Frame(_) => {}
         }

examples/autobahn-server.rs

@@ -17,9 +17,9 @@ fn handle_client(stream: TcpStream) -> Result<()> {
     let mut socket = accept(stream).map_err(must_not_block)?;
     info!("Running test");
     loop {
-        match socket.read_message()? {
+        match socket.read()? {
             msg @ Message::Text(_) | msg @ Message::Binary(_) => {
-                socket.write_message(msg)?;
+                socket.send(msg)?;
             }
             Message::Ping(_) | Message::Pong(_) | Message::Close(_) | Message::Frame(_) => {}
         }

examples/client.rs

@@ -14,9 +14,9 @@ fn main() {
         println!("* {}", header);
     }
 
-    socket.write_message(Message::Text("Hello WebSocket".into())).unwrap();
+    socket.send(Message::Text("Hello WebSocket".into())).unwrap();
     loop {
-        let msg = socket.read_message().expect("Error reading message");
+        let msg = socket.read().expect("Error reading message");
         println!("Received: {}", msg);
     }
     // socket.close(None);

examples/server.rs

@@ -28,9 +28,9 @@ fn main() {
             let mut websocket = accept_hdr(stream.unwrap(), callback).unwrap();
 
             loop {
-                let msg = websocket.read_message().unwrap();
+                let msg = websocket.read().unwrap();
                 if msg.is_binary() || msg.is_text() {
-                    websocket.write_message(msg).unwrap();
+                    websocket.send(msg).unwrap();
                 }
             }
         });

examples/srv_accept_unmasked_frames.rs

@@ -27,20 +27,18 @@ fn main() {
             };
 
             let config = Some(WebSocketConfig {
-                max_send_queue: None,
-                max_message_size: None,
-                max_frame_size: None,
                 // This setting allows to accept client frames which are not masked
                 // This is not in compliance with RFC 6455 but might be handy in some
                 // rare cases where it is necessary to integrate with existing/legacy
                 // clients which are sending unmasked frames
                 accept_unmasked_frames: true,
+                ..<_>::default()
             });
 
             let mut websocket = accept_hdr_with_config(stream.unwrap(), callback, config).unwrap();
 
             loop {
-                let msg = websocket.read_message().unwrap();
+                let msg = websocket.read().unwrap();
                 if msg.is_binary() || msg.is_text() {
                     println!("received message {}", msg);
                 }

fuzz/fuzz_targets/read_message_client.rs

@@ -33,5 +33,5 @@ fuzz_target!(|data: &[u8]| {
     //let vector: Vec<u8> = data.into();
     let cursor = Cursor::new(data);
     let mut socket = WebSocket::from_raw_socket(WriteMoc(cursor), Role::Client, None);
-    socket.read_message().ok();
+    socket.read().ok();
 });

fuzz/fuzz_targets/read_message_server.rs

@@ -33,5 +33,5 @@ fuzz_target!(|data: &[u8]| {
     //let vector: Vec<u8> = data.into();
     let cursor = Cursor::new(data);
     let mut socket = WebSocket::from_raw_socket(WriteMoc(cursor), Role::Server, None);
-    socket.read_message().ok();
+    socket.read().ok();
 });

src/error.rs

@@ -53,9 +53,9 @@ pub enum Error {
     /// Protocol violation.
     #[error("WebSocket protocol error: {0}")]
     Protocol(#[from] ProtocolError),
-    /// Message send queue full.
-    #[error("Send queue is full")]
-    SendQueueFull(Message),
+    /// Message write buffer is full.
+    #[error("Write buffer is full")]
+    WriteBufferFull(Message),
     /// UTF coding error.
     #[error("UTF-8 encoding error")]
     Utf8,

src/protocol/frame/mod.rs

@@ -6,15 +6,14 @@ pub mod coding;
 mod frame;
 mod mask;
 
-use std::io::{Error as IoError, ErrorKind as IoErrorKind, Read, Write};
-
-use log::*;
-
-pub use self::frame::{CloseFrame, Frame, FrameHeader};
 use crate::{
     error::{CapacityError, Error, Result},
-    ReadBuffer,
+    Message, ReadBuffer,
 };
+use log::*;
+use std::io::{Error as IoError, ErrorKind as IoErrorKind, Read, Write};
+
+pub use self::frame::{CloseFrame, Frame, FrameHeader};
 
 /// A reader and writer for WebSocket frames.
 #[derive(Debug)]
@@ -57,7 +56,7 @@ where
     Stream: Read,
 {
     /// Read a frame from stream.
-    pub fn read_frame(&mut self, max_size: Option<usize>) -> Result<Option<Frame>> {
+    pub fn read(&mut self, max_size: Option<usize>) -> Result<Option<Frame>> {
         self.codec.read_frame(&mut self.stream, max_size)
     }
 }
@@ -66,18 +65,28 @@ impl<Stream> FrameSocket<Stream>
 where
     Stream: Write,
 {
+    /// Writes and immediately flushes a frame.
+    /// Equivalent to calling [`write`](Self::write) then [`flush`](Self::flush).
+    pub fn send(&mut self, frame: Frame) -> Result<()> {
+        self.write(frame)?;
+        self.flush()
+    }
+
     /// Write a frame to stream.
     ///
-    /// This function guarantees that the frame is queued regardless of any errors.
-    /// There is no need to resend the frame. In order to handle WouldBlock or Incomplete,
-    /// call write_pending() afterwards.
-    pub fn write_frame(&mut self, frame: Frame) -> Result<()> {
+    /// A subsequent call should be made to [`flush`](Self::flush) to flush writes.
+    ///
+    /// This function guarantees that the frame is queued unless [`Error::WriteBufferFull`]
+    /// is returned.
+    /// In order to handle WouldBlock or Incomplete, call [`flush`](Self::flush) afterwards.
+    pub fn write(&mut self, frame: Frame) -> Result<()> {
         self.codec.write_frame(&mut self.stream, frame)
     }
 
-    /// Complete pending write, if any.
-    pub fn write_pending(&mut self) -> Result<()> {
-        self.codec.write_pending(&mut self.stream)
+    /// Flush writes.
+    pub fn flush(&mut self) -> Result<()> {
+        self.codec.write_out_buffer(&mut self.stream)?;
+        Ok(self.stream.flush()?)
     }
 }
 
@@ -88,6 +97,8 @@ pub(super) struct FrameCodec {
     in_buffer: ReadBuffer,
     /// Buffer to send packets to the network.
     out_buffer: Vec<u8>,
+    /// Capacity limit for `out_buffer`.
+    max_out_buffer_len: usize,
     /// Header and remaining size of the incoming packet being processed.
     header: Option<(FrameHeader, u64)>,
 }
@@ -95,7 +106,12 @@ pub(super) struct FrameCodec {
 impl FrameCodec {
     /// Create a new frame codec.
     pub(super) fn new() -> Self {
-        Self { in_buffer: ReadBuffer::new(), out_buffer: Vec::new(), header: None }
+        Self {
+            in_buffer: ReadBuffer::new(),
+            out_buffer: Vec::new(),
+            max_out_buffer_len: usize::MAX,
+            header: None,
+        }
     }
 
     /// Create a new frame codec from partially read data.
@@ -103,10 +119,22 @@ impl FrameCodec {
         Self {
             in_buffer: ReadBuffer::from_partially_read(part),
             out_buffer: Vec::new(),
+            max_out_buffer_len: usize::MAX,
             header: None,
         }
     }
 
+    /// Sets a maximum size for the out buffer.
+    pub(super) fn with_max_out_buffer_len(mut self, max: usize) -> Self {
+        self.max_out_buffer_len = max;
+        self
+    }
+
+    /// Sets a maximum size for the out buffer.
+    pub(super) fn set_max_out_buffer_len(&mut self, max: usize) {
+        self.max_out_buffer_len = max;
+    }
+
     /// Read a frame from the provided stream.
     pub(super) fn read_frame<Stream>(
         &mut self,
@@ -166,18 +194,28 @@ impl FrameCodec {
     }
 
     /// Write a frame to the provided stream.
+    ///
+    /// Does **not** flush.
     pub(super) fn write_frame<Stream>(&mut self, stream: &mut Stream, frame: Frame) -> Result<()>
     where
         Stream: Write,
     {
+        if frame.len() + self.out_buffer.len() > self.max_out_buffer_len {
+            return Err(Error::WriteBufferFull(Message::Frame(frame)));
+        }
+
         trace!("writing frame {}", frame);
+
         self.out_buffer.reserve(frame.len());
         frame.format(&mut self.out_buffer).expect("Bug: can't write to vector");
-        self.write_pending(stream)
+
+        self.write_out_buffer(stream)
     }
 
-    /// Complete pending write, if any.
-    pub(super) fn write_pending<Stream>(&mut self, stream: &mut Stream) -> Result<()>
+    /// Write any buffered frames to the provided stream.
+    ///
+    /// Does **not** flush.
+    pub(super) fn write_out_buffer<Stream>(&mut self, stream: &mut Stream) -> Result<()>
     where
         Stream: Write,
     {
@@ -193,16 +231,8 @@ impl FrameCodec {
             }
             self.out_buffer.drain(0..len);
         }
-        stream.flush()?;
-        Ok(())
-    }
-}
 
-#[cfg(test)]
-impl FrameCodec {
-    /// Returns the size of the output buffer.
-    pub(super) fn output_buffer_len(&self) -> usize {
-        self.out_buffer.len()
+        Ok(())
     }
 }
 
@@ -224,11 +254,11 @@ mod tests {
         let mut sock = FrameSocket::new(raw);
 
         assert_eq!(
-            sock.read_frame(None).unwrap().unwrap().into_data(),
+            sock.read(None).unwrap().unwrap().into_data(),
             vec![0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07]
         );
-        assert_eq!(sock.read_frame(None).unwrap().unwrap().into_data(), vec![0x03, 0x02, 0x01]);
-        assert!(sock.read_frame(None).unwrap().is_none());
+        assert_eq!(sock.read(None).unwrap().unwrap().into_data(), vec![0x03, 0x02, 0x01]);
+        assert!(sock.read(None).unwrap().is_none());
 
         let (_, rest) = sock.into_inner();
         assert_eq!(rest, vec![0x99]);
@@ -239,7 +269,7 @@ mod tests {
         let raw = Cursor::new(vec![0x02, 0x03, 0x04, 0x05, 0x06, 0x07]);
         let mut sock = FrameSocket::from_partially_read(raw, vec![0x82, 0x07, 0x01]);
         assert_eq!(
-            sock.read_frame(None).unwrap().unwrap().into_data(),
+            sock.read(None).unwrap().unwrap().into_data(),
             vec![0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07]
         );
     }
@@ -249,10 +279,10 @@ mod tests {
         let mut sock = FrameSocket::new(Vec::new());
 
         let frame = Frame::ping(vec![0x04, 0x05]);
-        sock.write_frame(frame).unwrap();
+        sock.send(frame).unwrap();
 
         let frame = Frame::pong(vec![0x01]);
-        sock.write_frame(frame).unwrap();
+        sock.send(frame).unwrap();
 
         let (buf, _) = sock.into_inner();
         assert_eq!(buf, vec![0x89, 0x02, 0x04, 0x05, 0x8a, 0x01, 0x01]);
@@ -264,7 +294,7 @@ mod tests {
             0x83, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x00, 0x00, 0x00, 0x00,
         ]);
         let mut sock = FrameSocket::new(raw);
-        let _ = sock.read_frame(None); // should not crash
+        let _ = sock.read(None); // should not crash
     }
 
     #[test]
@@ -272,7 +302,7 @@ mod tests {
         let raw = Cursor::new(vec![0x82, 0x07, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07]);
         let mut sock = FrameSocket::new(raw);
         assert!(matches!(
-            sock.read_frame(Some(5)),
+            sock.read(Some(5)),
             Err(Error::Capacity(CapacityError::MessageTooLong { size: 7, max_size: 5 }))
         ));
     }

src/protocol/message.rs

@@ -185,7 +185,7 @@ impl Message {
         Message::Text(string.into())
     }
 
-    /// Create a new binary WebSocket message by converting to Vec<u8>.
+    /// Create a new binary WebSocket message by converting to `Vec<u8>`.
     pub fn binary<B>(bin: B) -> Message
     where
         B: Into<Vec<u8>>,

src/protocol/mod.rs

@@ -6,13 +6,6 @@ mod message;
 
 pub use self::{frame::CloseFrame, message::Message};
 
-use log::*;
-use std::{
-    collections::VecDeque,
-    io::{ErrorKind as IoErrorKind, Read, Write},
-    mem::replace,
-};
-
 use self::{
     frame::{
         coding::{CloseCode, Control as OpCtl, Data as OpData, OpCode},
@@ -24,6 +17,11 @@ use crate::{
     error::{Error, ProtocolError, Result},
     util::NonBlockingResult,
 };
+use log::*;
+use std::{
+    io::{ErrorKind as IoErrorKind, Read, Write},
+    mem::replace,
+};
 
 /// Indicates a Client or Server role of the websocket
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
@@ -37,10 +35,12 @@ pub enum Role {
 /// The configuration for WebSocket connection.
 #[derive(Debug, Clone, Copy)]
 pub struct WebSocketConfig {
-    /// The size of the send queue. You can use it to turn on/off the backpressure features. `None`
-    /// means here that the size of the queue is unlimited. The default value is the unlimited
-    /// queue.
+    /// Does nothing, instead use `max_write_buffer_size`.
+    #[deprecated]
     pub max_send_queue: Option<usize>,
+    /// The max size of the write buffer in bytes. Setting this can provide backpressure.
+    /// The default value is unlimited.
+    pub max_write_buffer_size: usize,
     /// The maximum size of a message. `None` means no size limit. The default value is 64 MiB
     /// which should be reasonably big for all normal use-cases but small enough to prevent
     /// memory eating by a malicious user.
@@ -60,8 +60,10 @@ pub struct WebSocketConfig {
 
 impl Default for WebSocketConfig {
     fn default() -> Self {
+        #[allow(deprecated)]
         WebSocketConfig {
             max_send_queue: None,
+            max_write_buffer_size: usize::MAX,
             max_message_size: Some(64 << 20),
             max_frame_size: Some(16 << 20),
             accept_unmasked_frames: false,
@@ -73,6 +75,8 @@ impl Default for WebSocketConfig {
 ///
 /// This is THE structure you want to create to be able to speak the WebSocket protocol.
 /// It may be created by calling `connect`, `accept` or `client` functions.
+///
+/// Use [`WebSocket::read`], [`WebSocket::send`] to received and send messages.
 #[derive(Debug)]
 pub struct WebSocket<Stream> {
     /// The underlying socket.
@@ -146,82 +150,116 @@ impl<Stream> WebSocket<Stream> {
 impl<Stream: Read + Write> WebSocket<Stream> {
     /// Read a message from stream, if possible.
     ///
-    /// This will queue responses to ping and close messages to be sent. It will call
-    /// `write_pending` before trying to read in order to make sure that those responses
-    /// make progress even if you never call `write_pending`. That does mean that they
-    /// get sent out earliest on the next call to `read_message`, `write_message` or `write_pending`.
+    /// This will also queue responses to ping and close messages. These responses
+    /// will be written and flushed on the next call to [`read`](Self::read),
+    /// [`write`](Self::write) or [`flush`](Self::flush).
     ///
-    /// ## Closing the connection
+    /// # Closing the connection
     /// When the remote endpoint decides to close the connection this will return
     /// the close message with an optional close frame.
     ///
-    /// You should continue calling `read_message`, `write_message` or `write_pending` to drive
-    /// the reply to the close frame until [Error::ConnectionClosed] is returned. Once that happens
-    /// it is safe to drop the underlying connection.
-    pub fn read_message(&mut self) -> Result<Message> {
-        self.context.read_message(&mut self.socket)
+    /// You should continue calling [`read`](Self::read), [`write`](Self::write) or
+    /// [`flush`](Self::flush) to drive the reply to the close frame until [`Error::ConnectionClosed`]
+    /// is returned. Once that happens it is safe to drop the underlying connection.
+    pub fn read(&mut self) -> Result<Message> {
+        self.context.read(&mut self.socket)
+    }
+
+    /// Writes and immediately flushes a message.
+    /// Equivalent to calling [`write`](Self::write) then [`flush`](Self::flush).
+    pub fn send(&mut self, message: Message) -> Result<()> {
+        self.write(message)?;
+        self.flush()
     }
 
-    /// Send a message to stream, if possible.
+    /// Write a message to the provided stream, if possible.
     ///
-    /// WebSocket will buffer a configurable number of messages at a time, except to reply to Ping
-    /// requests. A Pong reply will jump the queue because the
-    /// [websocket RFC](https://tools.ietf.org/html/rfc6455#section-5.5.2) specifies it should be sent
-    /// as soon as is practical.
+    /// A subsequent call should be made to [`flush`](Self::flush) to flush writes.
     ///
-    /// Note that upon receiving a ping message, tungstenite cues a pong reply automatically.
-    /// When you call either `read_message`, `write_message` or `write_pending` next it will try to send
-    /// that pong out if the underlying connection can take more data. This means you should not
-    /// respond to ping frames manually.
+    /// In the event of stream write failure the message frame will be stored
+    /// in the write buffer and will try again on the next call to [`write`](Self::write)
+    /// or [`flush`](Self::flush).
+    ///
+    /// If the write buffer would exceed the configured [`WebSocketConfig::max_write_buffer_size`]
+    /// [`Err(WriteBufferFull(msg_frame))`](Error::WriteBufferFull) is returned.
+    ///
+    /// This call will generally not flush. However, if there are queued automatic messages
+    /// they will be written and eagerly flushed.
+    ///
+    /// For example, upon receiving ping messages tungstenite queues pong replies automatically.
+    /// The next call to [`read`](Self::read), [`write`](Self::write) or [`flush`](Self::flush)
+    /// will write & flush the pong reply. This means you should not respond to ping frames manually.
     ///
     /// You can however send pong frames manually in order to indicate a unidirectional heartbeat
     /// as described in [RFC 6455](https://tools.ietf.org/html/rfc6455#section-5.5.3). Note that
-    /// if `read_message` returns a ping, you should call `write_pending` until it doesn't return
-    /// WouldBlock before passing a pong to `write_message`, otherwise the response to the
-    /// ping will not be sent, but rather replaced by your custom pong message.
+    /// if [`read`](Self::read) returns a ping, you should [`flush`](Self::flush) before passing
+    /// a custom pong to [`write`](Self::write), otherwise the automatic queued response to the
+    /// ping will not be sent as it will be replaced by your custom pong message.
     ///
-    /// ## Errors
-    /// - If the WebSocket's send queue is full, `SendQueueFull` will be returned
-    /// along with the passed message. Otherwise, the message is queued and Ok(()) is returned.
-    /// - If the connection is closed and should be dropped, this will return [Error::ConnectionClosed].
-    /// - If you try again after [Error::ConnectionClosed] was returned either from here or from `read_message`,
-    ///   [Error::AlreadyClosed] will be returned. This indicates a program error on your part.
-    /// - [Error::Io] is returned if the underlying connection returns an error
+    /// # Errors
+    /// - If the WebSocket's write buffer is full, [`Error::WriteBufferFull`] will be returned
+    ///   along with the equivalent passed message frame.
+    /// - If the connection is closed and should be dropped, this will return [`Error::ConnectionClosed`].
+    /// - If you try again after [`Error::ConnectionClosed`] was returned either from here or from
+    ///   [`read`](Self::read), [`Error::AlreadyClosed`] will be returned. This indicates a program
+    ///   error on your part.
+    /// - [`Error::Io`] is returned if the underlying connection returns an error
     ///   (consider these fatal except for WouldBlock).
-    /// - [Error::Capacity] if your message size is bigger than the configured max message size.
-    pub fn write_message(&mut self, message: Message) -> Result<()> {
-        self.context.write_message(&mut self.socket, message)
+    /// - [`Error::Capacity`] if your message size is bigger than the configured max message size.
+    pub fn write(&mut self, message: Message) -> Result<()> {
+        self.context.write(&mut self.socket, message)
     }
 
-    /// Flush the pending send queue.
-    pub fn write_pending(&mut self) -> Result<()> {
-        self.context.write_pending(&mut self.socket)
+    /// Flush writes.
+    ///
+    /// Ensures all messages previously passed to [`write`](Self::write) and automatic
+    /// queued pong responses are written & flushed into the underlying stream.
+    pub fn flush(&mut self) -> Result<()> {
+        self.context.flush(&mut self.socket)
     }
 
     /// Close the connection.
     ///
     /// This function guarantees that the close frame will be queued.
     /// There is no need to call it again. Calling this function is
-    /// the same as calling `write_message(Message::Close(..))`.
+    /// the same as calling `write(Message::Close(..))`.
     ///
-    /// After queuing the close frame you should continue calling `read_message` or
-    /// `write_pending` to drive the close handshake to completion.
+    /// After queuing the close frame you should continue calling [`read`](Self::read) or
+    /// [`flush`](Self::flush) to drive the close handshake to completion.
     ///
     /// The websocket RFC defines that the underlying connection should be closed
     /// by the server. Tungstenite takes care of this asymmetry for you.
     ///
     /// When the close handshake is finished (we have both sent and received
-    /// a close message), `read_message` or `write_pending` will return
+    /// a close message), [`read`](Self::read) or [`flush`](Self::flush) will return
     /// [Error::ConnectionClosed] if this endpoint is the server.
     ///
     /// If this endpoint is a client, [Error::ConnectionClosed] will only be
     /// returned after the server has closed the underlying connection.
     ///
     /// It is thus safe to drop the underlying connection as soon as [Error::ConnectionClosed]
-    /// is returned from `read_message` or `write_pending`.
+    /// is returned from [`read`](Self::read) or [`flush`](Self::flush).
     pub fn close(&mut self, code: Option<CloseFrame>) -> Result<()> {
         self.context.close(&mut self.socket, code)
     }
+
+    /// Old name for [`read`](Self::read).
+    #[deprecated(note = "Use `read`")]
+    pub fn read_message(&mut self) -> Result<Message> {
+        self.read()
+    }
+
+    /// Old name for [`send`](Self::send).
+    #[deprecated(note = "Use `send`")]
+    pub fn write_message(&mut self, message: Message) -> Result<()> {
+        self.send(message)
+    }
+
+    /// Old name for [`flush`](Self::flush).
+    #[deprecated(note = "Use `flush`")]
+    pub fn write_pending(&mut self) -> Result<()> {
+        self.flush()
+    }
 }
 
 /// A context for managing WebSocket stream.
@@ -235,10 +273,8 @@ pub struct WebSocketContext {
     state: WebSocketState,
     /// Receive: an incomplete message being processed.
     incomplete: Option<IncompleteMessage>,
-    /// Send: a data send queue.
-    send_queue: VecDeque<Frame>,
-    /// Send: an OOB pong message.
-    pong: Option<Frame>,
+    /// Send in addition to regular messages E.g. "pong" or "close".
+    additional_send: Option<Frame>,
     /// The configuration for the websocket session.
     config: WebSocketConfig,
 }
@@ -246,28 +282,32 @@ pub struct WebSocketContext {
 impl WebSocketContext {
     /// Create a WebSocket context that manages a post-handshake stream.
     pub fn new(role: Role, config: Option<WebSocketConfig>) -> Self {
+        let config = config.unwrap_or_default();
+
         WebSocketContext {
             role,
-            frame: FrameCodec::new(),
+            frame: FrameCodec::new().with_max_out_buffer_len(config.max_write_buffer_size),
             state: WebSocketState::Active,
             incomplete: None,
-            send_queue: VecDeque::new(),
-            pong: None,
-            config: config.unwrap_or_default(),
+            additional_send: None,
+            config,
         }
     }
 
     /// Create a WebSocket context that manages an post-handshake stream.
     pub fn from_partially_read(part: Vec<u8>, role: Role, config: Option<WebSocketConfig>) -> Self {
+        let config = config.unwrap_or_default();
         WebSocketContext {
-            frame: FrameCodec::from_partially_read(part),
-            ..WebSocketContext::new(role, config)
+            frame: FrameCodec::from_partially_read(part)
+                .with_max_out_buffer_len(config.max_write_buffer_size),
+            ..WebSocketContext::new(role, Some(config))
         }
     }
 
     /// Change the configuration.
     pub fn set_config(&mut self, set_func: impl FnOnce(&mut WebSocketConfig)) {
-        set_func(&mut self.config)
+        set_func(&mut self.config);
+        self.frame.set_max_out_buffer_len(self.config.max_write_buffer_size);
     }
 
     /// Read the configuration.
@@ -294,17 +334,23 @@ impl WebSocketContext {
     ///
     /// This function sends pong and close responses automatically.
     /// However, it never blocks on write.
-    pub fn read_message<Stream>(&mut self, stream: &mut Stream) -> Result<Message>
+    pub fn read<Stream>(&mut self, stream: &mut Stream) -> Result<Message>
     where
         Stream: Read + Write,
     {
         // Do not read from already closed connections.
-        self.state.check_active()?;
+        self.state.check_not_terminated()?;
 
         loop {
-            // Since we may get ping or close, we need to reply to the messages even during read.
-            // Thus we call write_pending() but ignore its blocking.
-            self.write_pending(stream).no_block()?;
+            if self.additional_send.is_some() {
+                // Since we may get ping or close, we need to reply to the messages even during read.
+                // Thus we flush but ignore its blocking.
+                self.flush(stream).no_block()?;
+            } else if self.role == Role::Server && !self.state.can_read() {
+                self.state = WebSocketState::Terminated;
+                return Err(Error::ConnectionClosed);
+            }
+
             // If we get here, either write blocks or we have nothing to write.
             // Thus if read blocks, just let it return WouldBlock.
             if let Some(message) = self.read_message_frame(stream)? {
@@ -314,78 +360,94 @@ impl WebSocketContext {
         }
     }
 
-    /// Send a message to the provided stream, if possible.
+    /// Write a message to the provided stream.
+    ///
+    /// A subsequent call should be made to [`flush`](Self::flush) to flush writes.
     ///
-    /// WebSocket will buffer a configurable number of messages at a time, except to reply to Ping
-    /// and Close requests. If the WebSocket's send queue is full, `SendQueueFull` will be returned
-    /// along with the passed message. Otherwise, the message is queued and Ok(()) is returned.
+    /// In the event of stream write failure the message frame will be stored
+    /// in the write buffer and will try again on the next call to [`write`](Self::write)
+    /// or [`flush`](Self::flush).
     ///
-    /// Note that only the last pong frame is stored to be sent, and only the
-    /// most recent pong frame is sent if multiple pong frames are queued.
-    pub fn write_message<Stream>(&mut self, stream: &mut Stream, message: Message) -> Result<()>
+    /// If the write buffer would exceed the configured [`WebSocketConfig::max_write_buffer_size`]
+    /// [`Err(WriteBufferFull(msg_frame))`](Error::WriteBufferFull) is returned.
+    pub fn write<Stream>(&mut self, stream: &mut Stream, message: Message) -> Result<()>
     where
         Stream: Read + Write,
     {
         // When terminated, return AlreadyClosed.
-        self.state.check_active()?;
+        self.state.check_not_terminated()?;
 
         // Do not write after sending a close frame.
         if !self.state.is_active() {
             return Err(Error::Protocol(ProtocolError::SendAfterClosing));
         }
 
-        if let Some(max_send_queue) = self.config.max_send_queue {
-            if self.send_queue.len() >= max_send_queue {
-                // Try to make some room for the new message.
-                // Do not return here if write would block, ignore WouldBlock silently
-                // since we must queue the message anyway.
-                self.write_pending(stream).no_block()?;
-            }
-
-            if self.send_queue.len() >= max_send_queue {
-                return Err(Error::SendQueueFull(message));
-            }
-        }
-
         let frame = match message {
             Message::Text(data) => Frame::message(data.into(), OpCode::Data(OpData::Text), true),
             Message::Binary(data) => Frame::message(data, OpCode::Data(OpData::Binary), true),
             Message::Ping(data) => Frame::ping(data),
             Message::Pong(data) => {
-                self.pong = Some(Frame::pong(data));
-                return self.write_pending(stream);
+                self.set_additional(Frame::pong(data));
+                // Note: user pongs can be user flushed so no need to flush here
+                return self._write(stream, None).map(|_| ());
             }
             Message::Close(code) => return self.close(stream, code),
             Message::Frame(f) => f,
         };
 
-        self.send_queue.push_back(frame);
-        self.write_pending(stream)
+        let should_flush = self._write(stream, Some(frame))?;
+        if should_flush {
+            self.flush(stream)?;
+        }
+        Ok(())
+    }
+
+    /// Flush writes.
+    ///
+    /// Ensures all messages previously passed to [`write`](Self::write) and automatically
+    /// queued pong responses are written & flushed into the `stream`.
+    #[inline]
+    pub fn flush<Stream>(&mut self, stream: &mut Stream) -> Result<()>
+    where
+        Stream: Read + Write,
+    {
+        self._write(stream, None)?;
+        Ok(stream.flush()?)
     }
 
-    /// Flush the pending send queue.
-    pub fn write_pending<Stream>(&mut self, stream: &mut Stream) -> Result<()>
+    /// Writes any data in the out_buffer, `additional_send` and given `data`.
+    ///
+    /// Does **not** flush.
+    ///
+    /// Returns true if the write contents indicate we should flush immediately.
+    fn _write<Stream>(&mut self, stream: &mut Stream, data: Option<Frame>) -> Result<bool>
     where
         Stream: Read + Write,
     {
-        // First, make sure we have no pending frame sending.
-        self.frame.write_pending(stream)?;
+        match data {
+            Some(data) => self.write_one_frame(stream, data)?,
+            None => self.frame.write_out_buffer(stream)?,
+        }
 
         // Upon receipt of a Ping frame, an endpoint MUST send a Pong frame in
         // response, unless it already received a Close frame. It SHOULD
         // respond with Pong frame as soon as is practical. (RFC 6455)
-        if let Some(pong) = self.pong.take() {
-            trace!("Sending pong reply");
-            self.send_one_frame(stream, pong)?;
-        }
-        // If we have any unsent frames, send them.
-        trace!("Frames still in queue: {}", self.send_queue.len());
-        while let Some(data) = self.send_queue.pop_front() {
-            self.send_one_frame(stream, data)?;
-        }
-
-        // If we get to this point, the send queue is empty and the underlying socket is still
-        // willing to take more data.
+        let should_flush = if let Some(msg) = self.additional_send.take() {
+            trace!("Sending pong/close");
+            match self.write_one_frame(stream, msg) {
+                Err(Error::WriteBufferFull(Message::Frame(msg))) => {
+                    // if an system message would exceed the buffer put it back in
+                    // `additional_send` for retry. Otherwise returning this error
+                    // may not make sense to the user, e.g. calling `flush`.
+                    self.set_additional(msg);
+                    false
+                }
+                Err(err) => return Err(err),
+                Ok(_) => true,
+            }
+        } else {
+            false
+        };
 
         // If we're closing and there is nothing to send anymore, we should close the connection.
         if self.role == Role::Server && !self.state.can_read() {
@@ -398,7 +460,7 @@ impl WebSocketContext {
             self.state = WebSocketState::Terminated;
             Err(Error::ConnectionClosed)
         } else {
-            Ok(())
+            Ok(should_flush)
         }
     }
 
@@ -414,11 +476,11 @@ impl WebSocketContext {
         if let WebSocketState::Active = self.state {
             self.state = WebSocketState::ClosedByUs;
             let frame = Frame::close(code);
-            self.send_queue.push_back(frame);
+            self._write(stream, Some(frame))?;
         } else {
             // Already closed, nothing to do.
         }
-        self.write_pending(stream)
+        Ok(stream.flush()?)
     }
 
     /// Try to decode one message frame. May return None.
@@ -487,7 +549,7 @@ impl WebSocketContext {
                             let data = frame.into_data();
                             // No ping processing after we sent a close frame.
                             if self.state.is_active() {
-                                self.pong = Some(Frame::pong(data.clone()));
+                                self.set_additional(Frame::pong(data.clone()));
                             }
                             Ok(Some(Message::Ping(data)))
                         }
@@ -571,7 +633,7 @@ impl WebSocketContext {
 
                 let reply = Frame::close(close.clone());
                 debug!("Replying to close with {:?}", reply);
-                self.send_queue.push_back(reply);
+                self.set_additional(reply);
 
                 Some(close)
             }
@@ -588,8 +650,8 @@ impl WebSocketContext {
         }
     }
 
-    /// Send a single pending frame.
-    fn send_one_frame<Stream>(&mut self, stream: &mut Stream, mut frame: Frame) -> Result<()>
+    /// Write a single frame into the stream via the write-buffer.
+    fn write_one_frame<Stream>(&mut self, stream: &mut Stream, mut frame: Frame) -> Result<()>
     where
         Stream: Read + Write,
     {
@@ -605,6 +667,17 @@ impl WebSocketContext {
         trace!("Sending frame: {:?}", frame);
         self.frame.write_frame(stream, frame).check_connection_reset(self.state)
     }
+
+    /// Replace `additional_send` if it is currently a `Pong` message.
+    fn set_additional(&mut self, add: Frame) {
+        let empty_or_pong = self
+            .additional_send
+            .as_ref()
+            .map_or(true, |f| f.header().opcode == OpCode::Control(OpCtl::Pong));
+        if empty_or_pong {
+            self.additional_send.replace(add);
+        }
+    }
 }
 
 /// The current connection state.
@@ -636,7 +709,7 @@ impl WebSocketState {
     }
 
     /// Check if the state is active, return error if not.
-    fn check_active(self) -> Result<()> {
+    fn check_not_terminated(self) -> Result<()> {
         match self {
             WebSocketState::Terminated => Err(Error::AlreadyClosed),
             _ => Ok(()),
@@ -688,64 +761,6 @@ mod tests {
         }
     }
 
-    struct WouldBlockStreamMoc;
-
-    impl io::Write for WouldBlockStreamMoc {
-        fn write(&mut self, _: &[u8]) -> io::Result<usize> {
-            Err(io::Error::new(io::ErrorKind::WouldBlock, "would block"))
-        }
-        fn flush(&mut self) -> io::Result<()> {
-            Err(io::Error::new(io::ErrorKind::WouldBlock, "would block"))
-        }
-    }
-
-    impl io::Read for WouldBlockStreamMoc {
-        fn read(&mut self, _: &mut [u8]) -> io::Result<usize> {
-            Err(io::Error::new(io::ErrorKind::WouldBlock, "would block"))
-        }
-    }
-
-    #[test]
-    fn queue_logic() {
-        // Create a socket with the queue size of 1.
-        let mut socket = WebSocket::from_raw_socket(
-            WouldBlockStreamMoc,
-            Role::Client,
-            Some(WebSocketConfig { max_send_queue: Some(1), ..Default::default() }),
-        );
-
-        // Test message that we're going to send.
-        let message = Message::Binary(vec![0xFF; 1024]);
-
-        // Helper to check the error.
-        let assert_would_block = |error| {
-            if let Error::Io(io_error) = error {
-                assert_eq!(io_error.kind(), io::ErrorKind::WouldBlock);
-            } else {
-                panic!("Expected WouldBlock error");
-            }
-        };
-
-        // The first attempt of writing must not fail, since the queue is empty at start.
-        // But since the underlying mock object always returns `WouldBlock`, so is the result.
-        assert_would_block(dbg!(socket.write_message(message.clone()).unwrap_err()));
-
-        // Any subsequent attempts must return an error telling that the queue is full.
-        for _i in 0..100 {
-            assert!(matches!(
-                socket.write_message(message.clone()).unwrap_err(),
-                Error::SendQueueFull(..)
-            ));
-        }
-
-        // The size of the output buffer must not be bigger than the size of that message
-        // that we managed to write to the output buffer at first. Since we could not make
-        // any progress (because of the logic of the moc buffer), the size remains unchanged.
-        if socket.context.frame.output_buffer_len() > message.len() {
-            panic!("Too many frames in the queue");
-        }
-    }
-
     #[test]
     fn receive_messages() {
         let incoming = Cursor::new(vec![
@@ -754,10 +769,10 @@ mod tests {
             0x03,
         ]);
         let mut socket = WebSocket::from_raw_socket(WriteMoc(incoming), Role::Client, None);
-        assert_eq!(socket.read_message().unwrap(), Message::Ping(vec![1, 2]));
-        assert_eq!(socket.read_message().unwrap(), Message::Pong(vec![3]));
-        assert_eq!(socket.read_message().unwrap(), Message::Text("Hello, World!".into()));
-        assert_eq!(socket.read_message().unwrap(), Message::Binary(vec![0x01, 0x02, 0x03]));
+        assert_eq!(socket.read().unwrap(), Message::Ping(vec![1, 2]));
+        assert_eq!(socket.read().unwrap(), Message::Pong(vec![3]));
+        assert_eq!(socket.read().unwrap(), Message::Text("Hello, World!".into()));
+        assert_eq!(socket.read().unwrap(), Message::Binary(vec![0x01, 0x02, 0x03]));
     }
 
     #[test]
@@ -770,7 +785,7 @@ mod tests {
         let mut socket = WebSocket::from_raw_socket(WriteMoc(incoming), Role::Client, Some(limit));
 
         assert!(matches!(
-            socket.read_message(),
+            socket.read(),
             Err(Error::Capacity(CapacityError::MessageTooLong { size: 13, max_size: 10 }))
         ));
     }
@@ -782,7 +797,7 @@ mod tests {
         let mut socket = WebSocket::from_raw_socket(WriteMoc(incoming), Role::Client, Some(limit));
 
         assert!(matches!(
-            socket.read_message(),
+            socket.read(),
             Err(Error::Capacity(CapacityError::MessageTooLong { size: 3, max_size: 2 }))
         ));
     }

tests/connection_reset.rs

@@ -52,27 +52,27 @@ fn test_server_close() {
     do_test(
         3012,
         |mut cli_sock| {
-            cli_sock.write_message(Message::Text("Hello WebSocket".into())).unwrap();
+            cli_sock.send(Message::Text("Hello WebSocket".into())).unwrap();
 
-            let message = cli_sock.read_message().unwrap(); // receive close from server
+            let message = cli_sock.read().unwrap(); // receive close from server
             assert!(message.is_close());
 
-            let err = cli_sock.read_message().unwrap_err(); // now we should get ConnectionClosed
+            let err = cli_sock.read().unwrap_err(); // now we should get ConnectionClosed
             match err {
                 Error::ConnectionClosed => {}
                 _ => panic!("unexpected error: {:?}", err),
             }
         },
         |mut srv_sock| {
-            let message = srv_sock.read_message().unwrap();
+            let message = srv_sock.read().unwrap();
             assert_eq!(message.into_data(), b"Hello WebSocket");
 
             srv_sock.close(None).unwrap(); // send close to client
 
-            let message = srv_sock.read_message().unwrap(); // receive acknowledgement
+            let message = srv_sock.read().unwrap(); // receive acknowledgement
             assert!(message.is_close());
 
-            let err = srv_sock.read_message().unwrap_err(); // now we should get ConnectionClosed
+            let err = srv_sock.read().unwrap_err(); // now we should get ConnectionClosed
             match err {
                 Error::ConnectionClosed => {}
                 _ => panic!("unexpected error: {:?}", err),
@@ -86,26 +86,26 @@ fn test_evil_server_close() {
     do_test(
         3013,
         |mut cli_sock| {
-            cli_sock.write_message(Message::Text("Hello WebSocket".into())).unwrap();
+            cli_sock.send(Message::Text("Hello WebSocket".into())).unwrap();
 
             sleep(Duration::from_secs(1));
 
-            let message = cli_sock.read_message().unwrap(); // receive close from server
+            let message = cli_sock.read().unwrap(); // receive close from server
             assert!(message.is_close());
 
-            let err = cli_sock.read_message().unwrap_err(); // now we should get ConnectionClosed
+            let err = cli_sock.read().unwrap_err(); // now we should get ConnectionClosed
             match err {
                 Error::ConnectionClosed => {}
                 _ => panic!("unexpected error: {:?}", err),
             }
         },
         |mut srv_sock| {
-            let message = srv_sock.read_message().unwrap();
+            let message = srv_sock.read().unwrap();
             assert_eq!(message.into_data(), b"Hello WebSocket");
 
             srv_sock.close(None).unwrap(); // send close to client
 
-            let message = srv_sock.read_message().unwrap(); // receive acknowledgement
+            let message = srv_sock.read().unwrap(); // receive acknowledgement
             assert!(message.is_close());
             // and now just drop the connection without waiting for `ConnectionClosed`
             srv_sock.get_mut().set_linger(Some(Duration::from_secs(0))).unwrap();
@@ -119,32 +119,32 @@ fn test_client_close() {
     do_test(
         3014,
         |mut cli_sock| {
-            cli_sock.write_message(Message::Text("Hello WebSocket".into())).unwrap();
+            cli_sock.send(Message::Text("Hello WebSocket".into())).unwrap();
 
-            let message = cli_sock.read_message().unwrap(); // receive answer from server
+            let message = cli_sock.read().unwrap(); // receive answer from server
             assert_eq!(message.into_data(), b"From Server");
 
             cli_sock.close(None).unwrap(); // send close to server
 
-            let message = cli_sock.read_message().unwrap(); // receive acknowledgement from server
+            let message = cli_sock.read().unwrap(); // receive acknowledgement from server
             assert!(message.is_close());
 
-            let err = cli_sock.read_message().unwrap_err(); // now we should get ConnectionClosed
+            let err = cli_sock.read().unwrap_err(); // now we should get ConnectionClosed
             match err {
                 Error::ConnectionClosed => {}
                 _ => panic!("unexpected error: {:?}", err),
             }
         },
         |mut srv_sock| {
-            let message = srv_sock.read_message().unwrap();
+            let message = srv_sock.read().unwrap();
             assert_eq!(message.into_data(), b"Hello WebSocket");
 
-            srv_sock.write_message(Message::Text("From Server".into())).unwrap();
+            srv_sock.send(Message::Text("From Server".into())).unwrap();
 
-            let message = srv_sock.read_message().unwrap(); // receive close from client
+            let message = srv_sock.read().unwrap(); // receive close from client
             assert!(message.is_close());
 
-            let err = srv_sock.read_message().unwrap_err(); // now we should get ConnectionClosed
+            let err = srv_sock.read().unwrap_err(); // now we should get ConnectionClosed
             match err {
                 Error::ConnectionClosed => {}
                 _ => panic!("unexpected error: {:?}", err),

tests/no_send_after_close.rs

@@ -29,10 +29,10 @@ fn test_no_send_after_close() {
     let client_thread = spawn(move || {
         let (mut client, _) = connect(Url::parse("ws://localhost:3013/socket").unwrap()).unwrap();
 
-        let message = client.read_message().unwrap(); // receive close from server
+        let message = client.read().unwrap(); // receive close from server
         assert!(message.is_close());
 
-        let err = client.read_message().unwrap_err(); // now we should get ConnectionClosed
+        let err = client.read().unwrap_err(); // now we should get ConnectionClosed
         match err {
             Error::ConnectionClosed => {}
             _ => panic!("unexpected error: {:?}", err),
@@ -44,7 +44,7 @@ fn test_no_send_after_close() {
 
     client_handler.close(None).unwrap(); // send close to client
 
-    let err = client_handler.write_message(Message::Text("Hello WebSocket".into()));
+    let err = client_handler.send(Message::Text("Hello WebSocket".into()));
 
     assert!(err.is_err());
 

tests/receive_after_init_close.rs

@@ -29,12 +29,12 @@ fn test_receive_after_init_close() {
     let client_thread = spawn(move || {
         let (mut client, _) = connect(Url::parse("ws://localhost:3013/socket").unwrap()).unwrap();
 
-        client.write_message(Message::Text("Hello WebSocket".into())).unwrap();
+        client.send(Message::Text("Hello WebSocket".into())).unwrap();
 
-        let message = client.read_message().unwrap(); // receive close from server
+        let message = client.read().unwrap(); // receive close from server
         assert!(message.is_close());
 
-        let err = client.read_message().unwrap_err(); // now we should get ConnectionClosed
+        let err = client.read().unwrap_err(); // now we should get ConnectionClosed
         match err {
             Error::ConnectionClosed => {}
             _ => panic!("unexpected error: {:?}", err),
@@ -47,12 +47,12 @@ fn test_receive_after_init_close() {
     client_handler.close(None).unwrap(); // send close to client
 
     // This read should succeed even though we already initiated a close
-    let message = client_handler.read_message().unwrap();
+    let message = client_handler.read().unwrap();
     assert_eq!(message.into_data(), b"Hello WebSocket");
 
-    assert!(client_handler.read_message().unwrap().is_close()); // receive acknowledgement
+    assert!(client_handler.read().unwrap().is_close()); // receive acknowledgement
 
-    let err = client_handler.read_message().unwrap_err(); // now we should get ConnectionClosed
+    let err = client_handler.read().unwrap_err(); // now we should get ConnectionClosed
     match err {
         Error::ConnectionClosed => {}
         _ => panic!("unexpected error: {:?}", err),