lsp: Refactor duplex to avoid issues with select! + read_exact

read_exact isn't cancellation safe.

Fixes #504

helix-lsp/src/transport.rs

@@ -5,10 +5,14 @@
 use serde::{Deserialize, Serialize};
 use serde_json::Value;
 use std::collections::HashMap;
+use std::sync::Arc;
 use tokio::{
     io::{AsyncBufRead, AsyncBufReadExt, AsyncReadExt, AsyncWriteExt, BufReader, BufWriter},
     process::{ChildStderr, ChildStdin, ChildStdout},
-    sync::mpsc::{unbounded_channel, Sender, UnboundedReceiver, UnboundedSender},
+    sync::{
+        mpsc::{unbounded_channel, Sender, UnboundedReceiver, UnboundedSender},
+        Mutex,
+    },
 };
 
 #[derive(Debug)]
@@ -35,14 +39,7 @@ enum ServerMessage {
 #[derive(Debug)]
 pub struct Transport {
     id: usize,
-    client_tx: UnboundedSender<(usize, jsonrpc::Call)>,
-    client_rx: UnboundedReceiver<Payload>,
-
-    pending_requests: HashMap<jsonrpc::Id, Sender<Result<Value>>>,
-
-    server_stdin: BufWriter<ChildStdin>,
-    server_stdout: BufReader<ChildStdout>,
-    server_stderr: BufReader<ChildStderr>,
+    pending_requests: Mutex<HashMap<jsonrpc::Id, Sender<Result<Value>>>>,
 }
 
 impl Transport {
@@ -60,15 +57,14 @@ pub fn start(
 
         let transport = Self {
             id,
-            server_stdout,
-            server_stdin,
-            server_stderr,
-            client_tx,
-            client_rx,
-            pending_requests: HashMap::default(),
+            pending_requests: Mutex::new(HashMap::default()),
         };
 
-        tokio::spawn(transport.duplex());
+        let transport = Arc::new(transport);
+
+        tokio::spawn(Self::recv(transport.clone(), server_stdout, client_tx));
+        tokio::spawn(Self::err(transport.clone(), server_stderr));
+        tokio::spawn(Self::send(transport, server_stdin, client_rx));
 
         (rx, tx)
     }
@@ -109,12 +105,12 @@ async fn recv_server_message(
         //TODO: reuse vector
         let mut content = vec![0; content_length];
         reader.read_exact(&mut content).await?;
-        let msg = String::from_utf8(content).context("invalid utf8 from server")?;
+        let msg = std::str::from_utf8(&content).context("invalid utf8 from server")?;
 
         info!("<- {}", msg);
 
         // try parsing as output (server response) or call (server request)
-        let output: serde_json::Result<ServerMessage> = serde_json::from_str(&msg);
+        let output: serde_json::Result<ServerMessage> = serde_json::from_str(msg);
 
         Ok(output?)
     }
@@ -130,40 +126,55 @@ async fn recv_server_error(
         Ok(())
     }
 
-    async fn send_payload_to_server(&mut self, payload: Payload) -> Result<()> {
+    async fn send_payload_to_server(
+        &self,
+        server_stdin: &mut BufWriter<ChildStdin>,
+        payload: Payload,
+    ) -> Result<()> {
         //TODO: reuse string
         let json = match payload {
             Payload::Request { chan, value } => {
-                self.pending_requests.insert(value.id.clone(), chan);
+                self.pending_requests
+                    .lock()
+                    .await
+                    .insert(value.id.clone(), chan);
                 serde_json::to_string(&value)?
             }
             Payload::Notification(value) => serde_json::to_string(&value)?,
             Payload::Response(error) => serde_json::to_string(&error)?,
         };
-        self.send_string_to_server(json).await
+        self.send_string_to_server(server_stdin, json).await
     }
 
-    async fn send_string_to_server(&mut self, request: String) -> Result<()> {
+    async fn send_string_to_server(
+        &self,
+        server_stdin: &mut BufWriter<ChildStdin>,
+        request: String,
+    ) -> Result<()> {
         info!("-> {}", request);
 
         // send the headers
-        self.server_stdin
+        server_stdin
             .write_all(format!("Content-Length: {}\r\n\r\n", request.len()).as_bytes())
             .await?;
 
         // send the body
-        self.server_stdin.write_all(request.as_bytes()).await?;
+        server_stdin.write_all(request.as_bytes()).await?;
 
-        self.server_stdin.flush().await?;
+        server_stdin.flush().await?;
 
         Ok(())
     }
 
-    async fn process_server_message(&mut self, msg: ServerMessage) -> Result<()> {
+    async fn process_server_message(
+        &self,
+        client_tx: &UnboundedSender<(usize, jsonrpc::Call)>,
+        msg: ServerMessage,
+    ) -> Result<()> {
         match msg {
             ServerMessage::Output(output) => self.process_request_response(output).await?,
             ServerMessage::Call(call) => {
-                self.client_tx
+                client_tx
                     .send((self.id, call))
                     .context("failed to send a message to server")?;
                 // let notification = Notification::parse(&method, params);
@@ -172,7 +183,7 @@ async fn process_server_message(&mut self, msg: ServerMessage) -> Result<()> {
         Ok(())
     }
 
-    async fn process_request_response(&mut self, output: jsonrpc::Output) -> Result<()> {
+    async fn process_request_response(&self, output: jsonrpc::Output) -> Result<()> {
         let (id, result) = match output {
             jsonrpc::Output::Success(jsonrpc::Success { id, result, .. }) => {
                 info!("<- {}", result);
@@ -186,6 +197,8 @@ async fn process_request_response(&mut self, output: jsonrpc::Output) -> Result<
 
         let tx = self
             .pending_requests
+            .lock()
+            .await
             .remove(&id)
             .expect("pending_request with id not found!");
 
@@ -200,34 +213,51 @@ async fn process_request_response(&mut self, output: jsonrpc::Output) -> Result<
         Ok(())
     }
 
-    async fn duplex(mut self) {
+    async fn recv(
+        transport: Arc<Self>,
+        mut server_stdout: BufReader<ChildStdout>,
+        client_tx: UnboundedSender<(usize, jsonrpc::Call)>,
+    ) {
         let mut recv_buffer = String::new();
-        let mut err_buffer = String::new();
         loop {
-            tokio::select! {
-                // client -> server
-                msg = self.client_rx.recv() => {
-                    match msg {
-                        Some(msg) => {
-                            self.send_payload_to_server(msg).await.unwrap()
-                        },
-                        None => break
-                    }
+            match Self::recv_server_message(&mut server_stdout, &mut recv_buffer).await {
+                Ok(msg) => {
+                    transport
+                        .process_server_message(&client_tx, msg)
+                        .await
+                        .unwrap();
                 }
-                // server -> client
-                msg = Self::recv_server_message(&mut self.server_stdout, &mut recv_buffer) => {
-                    match msg {
-                        Ok(msg) => {
-                            self.process_server_message(msg).await.unwrap();
-                        }
-                        Err(_) => {
-                            error!("err: <- {:?}", msg);
-                            break;
-                        },
-                    }
+                Err(err) => {
+                    error!("err: <- {:?}", err);
+                    break;
                 }
-                _msg = Self::recv_server_error(&mut self.server_stderr, &mut err_buffer) => {}
             }
         }
     }
+
+    async fn err(_transport: Arc<Self>, mut server_stderr: BufReader<ChildStderr>) {
+        let mut recv_buffer = String::new();
+        loop {
+            match Self::recv_server_error(&mut server_stderr, &mut recv_buffer).await {
+                Ok(_) => {}
+                Err(err) => {
+                    error!("err: <- {:?}", err);
+                    break;
+                }
+            }
+        }
+    }
+
+    async fn send(
+        transport: Arc<Self>,
+        mut server_stdin: BufWriter<ChildStdin>,
+        mut client_rx: UnboundedReceiver<Payload>,
+    ) {
+        while let Some(msg) = client_rx.recv().await {
+            transport
+                .send_payload_to_server(&mut server_stdin, msg)
+                .await
+                .unwrap()
+        }
+    }
 }