2 files changed, 81 insertions, 10 deletions

diff --git a/cli/tests/unit/websocket_test.ts b/cli/tests/unit/websocket_test.ts
index 16384da40..ac33f9d69 100644
--- a/cli/tests/unit/websocket_test.ts
+++ b/cli/tests/unit/websocket_test.ts
@@ -100,7 +100,7 @@ Deno.test(
       promise.resolve();
     };
 
-    await Promise.all([promise, server]);
+    await Promise.all([promise, server.finished]);
     ws.close();
   },
 );
@@ -145,7 +145,57 @@ Deno.test({
   ws.onclose = () => {
     promise.resolve();
   };
-  await Promise.all([promise, server]);
+  await Promise.all([promise, server.finished]);
+});
+
+// https://github.com/denoland/deno/issues/19483
+Deno.test({
+  sanitizeOps: false,
+  sanitizeResources: false,
+}, async function websocketCloseFlushes() {
+  const promise = deferred();
+
+  const ac = new AbortController();
+  const listeningPromise = deferred();
+
+  const server = Deno.serve({
+    handler: (req) => {
+      const { response, socket } = Deno.upgradeWebSocket(req);
+      socket.onopen = () => socket.send("Hello");
+      socket.onmessage = () => {
+        socket.send("Bye");
+        socket.close();
+      };
+      socket.onclose = () => ac.abort();
+      socket.onerror = () => fail();
+      return response;
+    },
+    signal: ac.signal,
+    onListen: () => listeningPromise.resolve(),
+    hostname: "localhost",
+    port: 4247,
+  });
+
+  await listeningPromise;
+
+  const ws = new WebSocket("ws://localhost:4247/");
+  assertEquals(ws.url, "ws://localhost:4247/");
+  let seenBye = false;
+  ws.onerror = () => fail();
+  ws.onmessage = ({ data }) => {
+    if (data == "Hello") {
+      ws.send("Hello!");
+    } else {
+      assertEquals(data, "Bye");
+      seenBye = true;
+    }
+  };
+  ws.onclose = () => {
+    promise.resolve();
+  };
+  await Promise.all([promise, server.finished]);
+
+  assert(seenBye);
 });
 
 Deno.test(
diff --git a/ext/websocket/lib.rs b/ext/websocket/lib.rs
index bcbec2c5e..cbf9f8ff1 100644
--- a/ext/websocket/lib.rs
+++ b/ext/websocket/lib.rs
@@ -6,6 +6,7 @@ use deno_core::error::type_error;
 use deno_core::error::AnyError;
 use deno_core::op;
 use deno_core::url;
+use deno_core::AsyncMutFuture;
 use deno_core::AsyncRefCell;
 use deno_core::ByteString;
 use deno_core::CancelFuture;
@@ -354,12 +355,19 @@ impl ServerWebSocket {
     }
   }
 
+  /// Reserve a lock, but don't wait on it. This gets us our place in line.
+  pub fn reserve_lock(self: &Rc<Self>) -> AsyncMutFuture<()> {
+    RcRef::map(self, |r| &r.tx_lock).borrow_mut()
+  }
+
   #[inline]
   pub async fn write_frame(
     self: &Rc<Self>,
+    lock: AsyncMutFuture<()>,
     frame: Frame,
   ) -> Result<(), AnyError> {
-    let _lock = RcRef::map(self, |r| &r.tx_lock).borrow_mut().await;
+    lock.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.
@@ -407,9 +415,10 @@ pub fn op_ws_send_binary(
   let data = data.to_vec();
   let len = data.len();
   resource.buffered.set(resource.buffered.get() + len);
+  let lock = resource.reserve_lock();
   deno_core::task::spawn(async move {
     if let Err(err) = resource
-      .write_frame(Frame::new(true, OpCode::Binary, None, data))
+      .write_frame(lock, Frame::new(true, OpCode::Binary, None, data))
       .await
     {
       resource.set_error(Some(err.to_string()));
@@ -424,9 +433,13 @@ 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);
+  let lock = resource.reserve_lock();
   deno_core::task::spawn(async move {
     if let Err(err) = resource
-      .write_frame(Frame::new(true, OpCode::Text, None, data.into_bytes()))
+      .write_frame(
+        lock,
+        Frame::new(true, OpCode::Text, None, data.into_bytes()),
+      )
       .await
     {
       resource.set_error(Some(err.to_string()));
@@ -448,8 +461,9 @@ pub async fn op_ws_send_binary_async(
     .resource_table
     .get::<ServerWebSocket>(rid)?;
   let data = data.to_vec();
+  let lock = resource.reserve_lock();
   resource
-    .write_frame(Frame::new(true, OpCode::Binary, None, data))
+    .write_frame(lock, Frame::new(true, OpCode::Binary, None, data))
     .await
 }
 
@@ -464,8 +478,12 @@ pub async fn op_ws_send_text_async(
     .borrow_mut()
     .resource_table
     .get::<ServerWebSocket>(rid)?;
+  let lock = resource.reserve_lock();
   resource
-    .write_frame(Frame::new(true, OpCode::Text, None, data.into_bytes()))
+    .write_frame(
+      lock,
+      Frame::new(true, OpCode::Text, None, data.into_bytes()),
+    )
     .await
 }
 
@@ -488,7 +506,8 @@ pub async fn op_ws_send_pong(
     .borrow_mut()
     .resource_table
     .get::<ServerWebSocket>(rid)?;
-  resource.write_frame(Frame::pong(vec![])).await
+  let lock = resource.reserve_lock();
+  resource.write_frame(lock, Frame::pong(vec![])).await
 }
 
 #[op]
@@ -500,8 +519,9 @@ pub async fn op_ws_send_ping(
     .borrow_mut()
     .resource_table
     .get::<ServerWebSocket>(rid)?;
+  let lock = resource.reserve_lock();
   resource
-    .write_frame(Frame::new(true, OpCode::Ping, None, vec![]))
+    .write_frame(lock, Frame::new(true, OpCode::Ping, None, vec![]))
     .await
 }
 
@@ -521,7 +541,8 @@ pub async fn op_ws_close(
     .unwrap_or_else(|| Frame::close_raw(vec![]));
 
   resource.closed.set(true);
-  resource.write_frame(frame).await?;
+  let lock = resource.reserve_lock();
+  resource.write_frame(lock, frame).await?;
   Ok(())
 }