Auto merge of rust-lang#16226 - Veykril:lsp-server, r=Veykril

internal: Expose whether a channel has been dropped in lsp-server errors

Not the best way to expose this, but this should allow us to give somewhat better errors when the initialization request is malformed, as currently that just results in a channel disconnected error instead of the deserialization error. cc rust-lang/rust-analyzer#15859

Author: bors

Cargo.lock

@@ -88,7 +88,7 @@ test-utils = { path = "./crates/test-utils" }
 # In-tree crates that are published separately and follow semver. See lib/README.md
 line-index = { version = "0.1.1" }
 la-arena = { version = "0.3.1" }
-lsp-server = { version = "0.7.4" }
+lsp-server = { version = "0.7.6" }
 
 # non-local crates
 anyhow = "1.0.75"

Cargo.toml

@@ -172,7 +172,15 @@ fn run_server() -> anyhow::Result<()> {
 
     let (connection, io_threads) = Connection::stdio();
 
-    let (initialize_id, initialize_params) = connection.initialize_start()?;
+    let (initialize_id, initialize_params) = match connection.initialize_start() {
+        Ok(it) => it,
+        Err(e) => {
+            if e.channel_is_disconnected() {
+                io_threads.join()?;
+            }
+            return Err(e.into());
+        }
+    };
     tracing::info!("InitializeParams: {}", initialize_params);
     let lsp_types::InitializeParams {
         root_uri,
@@ -240,7 +248,12 @@ fn run_server() -> anyhow::Result<()> {
 
     let initialize_result = serde_json::to_value(initialize_result).unwrap();
 
-    connection.initialize_finish(initialize_id, initialize_result)?;
+    if let Err(e) = connection.initialize_finish(initialize_id, initialize_result) {
+        if e.channel_is_disconnected() {
+            io_threads.join()?;
+        }
+        return Err(e.into());
+    }
 
     if !config.has_linked_projects() && config.detached_files().is_empty() {
         config.rediscover_workspaces();

crates/rust-analyzer/src/bin/main.rs

@@ -1,6 +1,6 @@
 [package]
 name = "lsp-server"
-version = "0.7.5"
+version = "0.7.6"
 description = "Generic LSP server scaffold."
 license = "MIT OR Apache-2.0"
 repository = "https://github.com/rust-lang/rust-analyzer/tree/master/lib/lsp-server"
@@ -10,7 +10,7 @@ edition = "2021"
 log = "0.4.17"
 serde_json = "1.0.108"
 serde = { version = "1.0.192", features = ["derive"] }
-crossbeam-channel = "0.5.6"
+crossbeam-channel = "0.5.8"
 
 [dev-dependencies]
 lsp-types = "=0.95"

lib/lsp-server/Cargo.toml

@@ -64,7 +64,15 @@ fn main() -> Result<(), Box<dyn Error + Sync + Send>> {
         ..Default::default()
     })
     .unwrap();
-    let initialization_params = connection.initialize(server_capabilities)?;
+    let initialization_params = match connection.initialize(server_capabilities) {
+        Ok(it) => it,
+        Err(e) => {
+            if e.channel_is_disconnected() {
+                io_threads.join()?;
+            }
+            return Err(e.into());
+        }
+    };
     main_loop(connection, initialization_params)?;
     io_threads.join()?;
 

lib/lsp-server/examples/goto_def.rs

@@ -3,7 +3,22 @@ use std::fmt;
 use crate::{Notification, Request};
 
 #[derive(Debug, Clone, PartialEq)]
-pub struct ProtocolError(pub(crate) String);
+pub struct ProtocolError(String, bool);
+
+impl ProtocolError {
+    pub(crate) fn new(msg: impl Into<String>) -> Self {
+        ProtocolError(msg.into(), false)
+    }
+
+    pub(crate) fn disconnected() -> ProtocolError {
+        ProtocolError("disconnected channel".into(), true)
+    }
+
+    /// Whether this error occured due to a disconnected channel.
+    pub fn channel_is_disconnected(&self) -> bool {
+        self.1
+    }
+}
 
 impl std::error::Error for ProtocolError {}
 

lib/lsp-server/src/error.rs

@@ -17,7 +17,7 @@ use std::{
     net::{TcpListener, TcpStream, ToSocketAddrs},
 };
 
-use crossbeam_channel::{Receiver, RecvTimeoutError, Sender};
+use crossbeam_channel::{Receiver, RecvError, RecvTimeoutError, Sender};
 
 pub use crate::{
     error::{ExtractError, ProtocolError},
@@ -158,11 +158,7 @@ impl Connection {
                 Err(RecvTimeoutError::Timeout) => {
                     continue;
                 }
-                Err(e) => {
-                    return Err(ProtocolError(format!(
-                        "expected initialize request, got error: {e}"
-                    )))
-                }
+                Err(RecvTimeoutError::Disconnected) => return Err(ProtocolError::disconnected()),
             };
 
             match msg {
@@ -181,12 +177,14 @@ impl Connection {
                     continue;
                 }
                 msg => {
-                    return Err(ProtocolError(format!("expected initialize request, got {msg:?}")));
+                    return Err(ProtocolError::new(format!(
+                        "expected initialize request, got {msg:?}"
+                    )));
                 }
             };
         }
 
-        return Err(ProtocolError(String::from(
+        return Err(ProtocolError::new(String::from(
             "Initialization has been aborted during initialization",
         )));
     }
@@ -201,12 +199,10 @@ impl Connection {
         self.sender.send(resp.into()).unwrap();
         match &self.receiver.recv() {
             Ok(Message::Notification(n)) if n.is_initialized() => Ok(()),
-            Ok(msg) => {
-                Err(ProtocolError(format!(r#"expected initialized notification, got: {msg:?}"#)))
-            }
-            Err(e) => {
-                Err(ProtocolError(format!("expected initialized notification, got error: {e}",)))
-            }
+            Ok(msg) => Err(ProtocolError::new(format!(
+                r#"expected initialized notification, got: {msg:?}"#
+            ))),
+            Err(RecvError) => Err(ProtocolError::disconnected()),
         }
     }
 
@@ -231,10 +227,8 @@ impl Connection {
                 Err(RecvTimeoutError::Timeout) => {
                     continue;
                 }
-                Err(e) => {
-                    return Err(ProtocolError(format!(
-                        "expected initialized notification, got error: {e}",
-                    )));
+                Err(RecvTimeoutError::Disconnected) => {
+                    return Err(ProtocolError::disconnected());
                 }
             };
 
@@ -243,14 +237,14 @@ impl Connection {
                     return Ok(());
                 }
                 msg => {
-                    return Err(ProtocolError(format!(
+                    return Err(ProtocolError::new(format!(
                         r#"expected initialized notification, got: {msg:?}"#
                     )));
                 }
             }
         }
 
-        return Err(ProtocolError(String::from(
+        return Err(ProtocolError::new(String::from(
             "Initialization has been aborted during initialization",
         )));
     }
@@ -359,9 +353,18 @@ impl Connection {
         match &self.receiver.recv_timeout(std::time::Duration::from_secs(30)) {
             Ok(Message::Notification(n)) if n.is_exit() => (),
             Ok(msg) => {
-                return Err(ProtocolError(format!("unexpected message during shutdown: {msg:?}")))
+                return Err(ProtocolError::new(format!(
+                    "unexpected message during shutdown: {msg:?}"
+                )))
+            }
+            Err(RecvTimeoutError::Timeout) => {
+                return Err(ProtocolError::new(format!("timed out waiting for exit notification")))
+            }
+            Err(RecvTimeoutError::Disconnected) => {
+                return Err(ProtocolError::new(format!(
+                    "channel disconnected waiting for exit notification"
+                )))
             }
-            Err(e) => return Err(ProtocolError(format!("unexpected error during shutdown: {e}"))),
         }
         Ok(true)
     }
@@ -426,7 +429,7 @@ mod tests {
 
         initialize_start_test(TestCase {
             test_messages: vec![notification_msg.clone()],
-            expected_resp: Err(ProtocolError(format!(
+            expected_resp: Err(ProtocolError::new(format!(
                 "expected initialize request, got {:?}",
                 notification_msg
             ))),

lib/lsp-server/src/lib.rs

@@ -264,12 +264,12 @@ fn read_msg_text(inp: &mut dyn BufRead) -> io::Result<Option<String>> {
         let mut parts = buf.splitn(2, ": ");
         let header_name = parts.next().unwrap();
         let header_value =
-            parts.next().ok_or_else(|| invalid_data!("malformed header: {:?}", buf))?;
+            parts.next().ok_or_else(|| invalid_data(format!("malformed header: {:?}", buf)))?;
         if header_name.eq_ignore_ascii_case("Content-Length") {
             size = Some(header_value.parse::<usize>().map_err(invalid_data)?);
         }
     }
-    let size: usize = size.ok_or_else(|| invalid_data!("no Content-Length"))?;
+    let size: usize = size.ok_or_else(|| invalid_data("no Content-Length".to_string()))?;
     let mut buf = buf.into_bytes();
     buf.resize(size, 0);
     inp.read_exact(&mut buf)?;

lib/lsp-server/src/msg.rs

@@ -15,8 +15,7 @@ pub(crate) fn stdio_transport() -> (Sender<Message>, Receiver<Message>, IoThread
     let writer = thread::spawn(move || {
         let stdout = stdout();
         let mut stdout = stdout.lock();
-        writer_receiver.into_iter().try_for_each(|it| it.write(&mut stdout))?;
-        Ok(())
+        writer_receiver.into_iter().try_for_each(|it| it.write(&mut stdout))
     });
     let (reader_sender, reader_receiver) = bounded::<Message>(0);
     let reader = thread::spawn(move || {