perf(ext/websocket): Make send sync for non-stream websockets (#19376)

No need to go through the async machinery for `send(String | Buffer)` --
we can fire and forget, and then route any send errors into the async
call we're already making (`op_ws_next_event`).

Early benchmark on MacOS:

Before: 155.8k msg/sec
After: 166.2k msg/sec (+6.6%)

Co-authored-by: Bartek Iwańczuk <biwanczuk@gmail.com>

ext/websocket/01_websocket.js

@@ -23,12 +23,10 @@ const primordials = globalThis.__bootstrap.primordials;
 const {
   ArrayBufferPrototype,
   ArrayBufferIsView,
-  ArrayBufferPrototypeGetByteLength,
   ArrayPrototypeJoin,
   ArrayPrototypeMap,
   ArrayPrototypeSome,
   DataView,
-  DataViewPrototypeGetByteLength,
   ErrorPrototypeToString,
   ObjectDefineProperties,
   ObjectPrototypeIsPrototypeOf,
@@ -46,7 +44,6 @@ const {
   PromisePrototypeCatch,
   SymbolFor,
   TypedArrayPrototypeGetByteLength,
-  TypedArrayPrototypeGetSymbolToStringTag,
 } = primordials;
 const op_ws_check_permission_and_cancel_handle =
   core.ops.op_ws_check_permission_and_cancel_handle;
@@ -57,6 +54,7 @@ const {
   op_ws_send_text,
   op_ws_next_event,
   op_ws_send_ping,
+  op_ws_get_buffered_amount,
 } = core.ensureFastOps();
 
 webidl.converters["sequence<DOMString> or DOMString"] = (
@@ -111,7 +109,6 @@ const _role = Symbol("[[role]]");
 const _extensions = Symbol("[[extensions]]");
 const _protocol = Symbol("[[protocol]]");
 const _binaryType = Symbol("[[binaryType]]");
-const _bufferedAmount = Symbol("[[bufferedAmount]]");
 const _eventLoop = Symbol("[[eventLoop]]");
 
 const _server = Symbol("[[server]]");
@@ -179,10 +176,13 @@ class WebSocket extends EventTarget {
     }
   }
 
-  [_bufferedAmount] = 0;
   get bufferedAmount() {
     webidl.assertBranded(this, WebSocketPrototype);
-    return this[_bufferedAmount];
+    if (this[_readyState] === OPEN) {
+      return op_ws_get_buffered_amount(this[_rid]);
+    } else {
+      return 0;
+    }
   }
 
   constructor(url, protocols = []) {
@@ -318,55 +318,25 @@ class WebSocket extends EventTarget {
       throw new DOMException("readyState not OPEN", "InvalidStateError");
     }
 
-    /**
-     * @param {ArrayBufferView} view
-     * @param {number} byteLength
-     */
-    const sendTypedArray = (view, byteLength) => {
-      this[_bufferedAmount] += byteLength;
-      PromisePrototypeThen(
-        op_ws_send_binary(
-          this[_rid],
-          view,
-        ),
-        () => {
-          this[_bufferedAmount] -= byteLength;
-        },
-      );
-    };
-
     if (ObjectPrototypeIsPrototypeOf(BlobPrototype, data)) {
       PromisePrototypeThen(
         // deno-lint-ignore prefer-primordials
         data.slice().arrayBuffer(),
         (ab) =>
-          sendTypedArray(
+          op_ws_send_binary(
+            this[_rid],
             new DataView(ab),
-            ArrayBufferPrototypeGetByteLength(ab),
           ),
       );
     } else if (ArrayBufferIsView(data)) {
-      if (TypedArrayPrototypeGetSymbolToStringTag(data) === undefined) {
-        // DataView
-        sendTypedArray(data, DataViewPrototypeGetByteLength(data));
-      } else {
-        // TypedArray
-        sendTypedArray(data, TypedArrayPrototypeGetByteLength(data));
-      }
+      op_ws_send_binary(this[_rid], data);
     } else if (ObjectPrototypeIsPrototypeOf(ArrayBufferPrototype, data)) {
-      sendTypedArray(data, ArrayBufferPrototypeGetByteLength(data));
+      op_ws_send_binary(this[_rid], data);
     } else {
       const string = String(data);
-      const d = core.encode(string);
-      this[_bufferedAmount] += TypedArrayPrototypeGetByteLength(d);
-      PromisePrototypeThen(
-        op_ws_send_text(
-          this[_rid],
-          string,
-        ),
-        () => {
-          this[_bufferedAmount] -= TypedArrayPrototypeGetByteLength(d);
-        },
+      op_ws_send_text(
+        this[_rid],
+        string,
       );
     }
   }

ext/websocket/02_websocketstream.js

@@ -34,8 +34,8 @@ const {
   Uint8ArrayPrototype,
 } = primordials;
 const {
-  op_ws_send_text,
-  op_ws_send_binary,
+  op_ws_send_text_async,
+  op_ws_send_binary_async,
   op_ws_next_event,
   op_ws_create,
   op_ws_close,
@@ -210,11 +210,11 @@ class WebSocketStream {
             const writable = new WritableStream({
               write: async (chunk) => {
                 if (typeof chunk === "string") {
-                  await op_ws_send_text(this[_rid], chunk);
+                  await op_ws_send_text_async(this[_rid], chunk);
                 } else if (
                   ObjectPrototypeIsPrototypeOf(Uint8ArrayPrototype, chunk)
                 ) {
-                  await op_ws_send_binary(this[_rid], chunk);
+                  await op_ws_send_binary_async(this[_rid], chunk);
                 } else {
                   throw new TypeError(
                     "A chunk may only be either a string or an Uint8Array",

ext/websocket/lib.rs

@@ -281,8 +281,10 @@ where
   }
 
   let resource = ServerWebSocket {
+    buffered: Cell::new(0),
+    errored: Cell::new(None),
     ws: AsyncRefCell::new(FragmentCollector::new(stream)),
-    closed: Rc::new(Cell::new(false)),
+    closed: Cell::new(false),
     tx_lock: AsyncRefCell::new(()),
   };
   let mut state = state.borrow_mut();
@@ -315,18 +317,20 @@ pub enum MessageKind {
 }
 
 pub struct ServerWebSocket {
+  buffered: Cell<usize>,
+  errored: Cell<Option<AnyError>>,
   ws: AsyncRefCell<FragmentCollector<WebSocketStream>>,
-  closed: Rc<Cell<bool>>,
+  closed: Cell<bool>,
   tx_lock: AsyncRefCell<()>,
 }
 
 impl ServerWebSocket {
   #[inline]
   pub async fn write_frame(
-    self: Rc<Self>,
+    self: &Rc<Self>,
     frame: Frame,
   ) -> Result<(), AnyError> {
-    let _lock = RcRef::map(&self, |r| &r.tx_lock).borrow_mut().await;
+    let _lock = RcRef::map(self, |r| &r.tx_lock).borrow_mut().await;
     // SAFETY: fastwebsockets only needs a mutable reference to the WebSocket
     // to populate the write buffer. We encounter an await point when writing
     // to the socket after the frame has already been written to the buffer.
@@ -361,8 +365,10 @@ pub fn ws_create_server_stream(
   ws.set_auto_pong(true);
 
   let ws_resource = ServerWebSocket {
+    buffered: Cell::new(0),
+    errored: Cell::new(None),
     ws: AsyncRefCell::new(FragmentCollector::new(ws)),
-    closed: Rc::new(Cell::new(false)),
+    closed: Cell::new(false),
     tx_lock: AsyncRefCell::new(()),
   };
 
@@ -370,8 +376,48 @@ pub fn ws_create_server_stream(
   Ok(rid)
 }
 
-#[op]
-pub async fn op_ws_send_binary(
+#[op(fast)]
+pub fn op_ws_send_binary(
+  state: &mut OpState,
+  rid: ResourceId,
+  data: ZeroCopyBuf,
+) {
+  let resource = state.resource_table.get::<ServerWebSocket>(rid).unwrap();
+  let data = data.to_vec();
+  let len = data.len();
+  resource.buffered.set(resource.buffered.get() + len);
+  deno_core::task::spawn(async move {
+    if let Err(err) = resource
+      .write_frame(Frame::new(true, OpCode::Binary, None, data))
+      .await
+    {
+      resource.errored.set(Some(err));
+    } else {
+      resource.buffered.set(resource.buffered.get() - len);
+    }
+  });
+}
+
+#[op(fast)]
+pub fn op_ws_send_text(state: &mut OpState, rid: ResourceId, data: String) {
+  let resource = state.resource_table.get::<ServerWebSocket>(rid).unwrap();
+  let len = data.len();
+  resource.buffered.set(resource.buffered.get() + len);
+  deno_core::task::spawn(async move {
+    if let Err(err) = resource
+      .write_frame(Frame::new(true, OpCode::Text, None, data.into_bytes()))
+      .await
+    {
+      resource.errored.set(Some(err));
+    } else {
+      resource.buffered.set(resource.buffered.get() - len);
+    }
+  });
+}
+
+/// Async version of send. Does not update buffered amount as we rely on the socket itself for backpressure.
+#[op(fast)]
+pub async fn op_ws_send_binary_async(
   state: Rc<RefCell<OpState>>,
   rid: ResourceId,
   data: ZeroCopyBuf,
@@ -380,13 +426,15 @@ pub async fn op_ws_send_binary(
     .borrow_mut()
     .resource_table
     .get::<ServerWebSocket>(rid)?;
+  let data = data.to_vec();
   resource
-    .write_frame(Frame::new(true, OpCode::Binary, None, data.to_vec()))
+    .write_frame(Frame::new(true, OpCode::Binary, None, data))
     .await
 }
 
-#[op]
-pub async fn op_ws_send_text(
+/// Async version of send. Does not update buffered amount as we rely on the socket itself for backpressure.
+#[op(fast)]
+pub async fn op_ws_send_text_async(
   state: Rc<RefCell<OpState>>,
   rid: ResourceId,
   data: String,
@@ -400,6 +448,16 @@ pub async fn op_ws_send_text(
     .await
 }
 
+#[op(fast)]
+pub fn op_ws_get_buffered_amount(state: &mut OpState, rid: ResourceId) -> u32 {
+  state
+    .resource_table
+    .get::<ServerWebSocket>(rid)
+    .unwrap()
+    .buffered
+    .get() as u32
+}
+
 #[op]
 pub async fn op_ws_send_pong(
   state: Rc<RefCell<OpState>>,
@@ -441,8 +499,7 @@ pub async fn op_ws_close(
     .map(|reason| Frame::close(code.unwrap_or(1005), reason.as_bytes()))
     .unwrap_or_else(|| Frame::close_raw(vec![]));
 
-  let cell = Rc::clone(&resource.closed);
-  cell.set(true);
+  resource.closed.set(true);
   resource.write_frame(frame).await?;
   Ok(())
 }
@@ -457,6 +514,10 @@ pub async fn op_ws_next_event(
     .resource_table
     .get::<ServerWebSocket>(rid)?;
 
+  if let Some(err) = resource.errored.take() {
+    return Err(err);
+  }
+
   let mut ws = RcRef::map(&resource, |r| &r.ws).borrow_mut().await;
   loop {
     let val = match ws.read_frame().await {
@@ -519,8 +580,11 @@ deno_core::extension!(deno_websocket,
     op_ws_next_event,
     op_ws_send_binary,
     op_ws_send_text,
+    op_ws_send_binary_async,
+    op_ws_send_text_async,
     op_ws_send_ping,
     op_ws_send_pong,
+    op_ws_get_buffered_amount,
   ],
   esm = [ "01_websocket.js", "02_websocketstream.js" ],
   options = {