1 files changed, 119 insertions, 89 deletions

diff --git a/crates/flycheck/src/lib.rs b/crates/flycheck/src/lib.rs
index 92ec4f92e..1023d3040 100644
--- a/crates/flycheck/src/lib.rs
+++ b/crates/flycheck/src/lib.rs
@@ -5,8 +5,9 @@
 use std::{
     fmt,
     io::{self, BufReader},
+    ops,
     path::PathBuf,
-    process::{Command, Stdio},
+    process::{self, Command, Stdio},
     time::Duration,
 };
 
@@ -49,8 +50,8 @@ impl fmt::Display for FlycheckConfig {
 #[derive(Debug)]
 pub struct FlycheckHandle {
     // XXX: drop order is significant
-    cmd_send: Sender<Restart>,
-    handle: jod_thread::JoinHandle,
+    sender: Sender<Restart>,
+    thread: jod_thread::JoinHandle,
 }
 
 impl FlycheckHandle {
@@ -59,16 +60,15 @@ impl FlycheckHandle {
         config: FlycheckConfig,
         workspace_root: PathBuf,
     ) -> FlycheckHandle {
-        let (cmd_send, cmd_recv) = unbounded::<Restart>();
-        let handle = jod_thread::spawn(move || {
-            FlycheckActor::new(sender, config, workspace_root).run(cmd_recv);
-        });
-        FlycheckHandle { cmd_send, handle }
+        let actor = FlycheckActor::new(sender, config, workspace_root);
+        let (sender, receiver) = unbounded::<Restart>();
+        let thread = jod_thread::spawn(move || actor.run(receiver));
+        FlycheckHandle { sender, thread }
     }
 
     /// Schedule a re-start of the cargo check worker.
     pub fn update(&self) {
-        self.cmd_send.send(Restart).unwrap();
+        self.sender.send(Restart).unwrap();
     }
 }
 
@@ -85,7 +85,7 @@ pub enum Message {
 pub enum Progress {
     DidStart,
     DidCheckCrate(String),
-    DidFinish,
+    DidFinish(io::Result<()>),
     DidCancel,
 }
 
@@ -100,8 +100,7 @@ struct FlycheckActor {
     /// doesn't provide a way to read sub-process output without blocking, so we
     /// have to wrap sub-processes output handling in a thread and pass messages
     /// back over a channel.
-    // XXX: drop order is significant
-    check_process: Option<(Receiver<cargo_metadata::Message>, jod_thread::JoinHandle)>,
+    cargo_handle: Option<CargoHandle>,
 }
 
 enum Event {
@@ -115,29 +114,36 @@ impl FlycheckActor {
         config: FlycheckConfig,
         workspace_root: PathBuf,
     ) -> FlycheckActor {
-        FlycheckActor { sender, config, workspace_root, check_process: None }
+        FlycheckActor { sender, config, workspace_root, cargo_handle: None }
     }
     fn next_event(&self, inbox: &Receiver<Restart>) -> Option<Event> {
-        let check_chan = self.check_process.as_ref().map(|(chan, _thread)| chan);
+        let check_chan = self.cargo_handle.as_ref().map(|cargo| &cargo.receiver);
         select! {
             recv(inbox) -> msg => msg.ok().map(Event::Restart),
             recv(check_chan.unwrap_or(&never())) -> msg => Some(Event::CheckEvent(msg.ok())),
         }
     }
-    fn run(&mut self, inbox: Receiver<Restart>) {
+    fn run(mut self, inbox: Receiver<Restart>) {
         while let Some(event) = self.next_event(&inbox) {
             match event {
                 Event::Restart(Restart) => {
                     while let Ok(Restart) = inbox.recv_timeout(Duration::from_millis(50)) {}
+
                     self.cancel_check_process();
-                    self.check_process = Some(self.start_check_process());
-                    self.send(Message::Progress(Progress::DidStart));
+
+                    let mut command = self.check_command();
+                    command.stdout(Stdio::piped()).stderr(Stdio::null()).stdin(Stdio::null());
+                    if let Ok(child) = command.spawn().map(JodChild) {
+                        self.cargo_handle = Some(CargoHandle::spawn(child));
+                        self.send(Message::Progress(Progress::DidStart));
+                    }
                 }
                 Event::CheckEvent(None) => {
                     // Watcher finished, replace it with a never channel to
                     // avoid busy-waiting.
-                    assert!(self.check_process.take().is_some());
-                    self.send(Message::Progress(Progress::DidFinish));
+                    let cargo_handle = self.cargo_handle.take().unwrap();
+                    let res = cargo_handle.join();
+                    self.send(Message::Progress(Progress::DidFinish(res)));
                 }
                 Event::CheckEvent(Some(message)) => match message {
                     cargo_metadata::Message::CompilerArtifact(msg) => {
@@ -162,11 +168,11 @@ impl FlycheckActor {
         self.cancel_check_process();
     }
     fn cancel_check_process(&mut self) {
-        if self.check_process.take().is_some() {
+        if self.cargo_handle.take().is_some() {
             self.send(Message::Progress(Progress::DidCancel));
         }
     }
-    fn start_check_process(&self) -> (Receiver<cargo_metadata::Message>, jod_thread::JoinHandle) {
+    fn check_command(&self) -> Command {
         let mut cmd = match &self.config {
             FlycheckConfig::CargoCommand {
                 command,
@@ -198,33 +204,7 @@ impl FlycheckActor {
             }
         };
         cmd.current_dir(&self.workspace_root);
-
-        let (message_send, message_recv) = unbounded();
-        let thread = jod_thread::spawn(move || {
-            // If we trigger an error here, we will do so in the loop instead,
-            // which will break out of the loop, and continue the shutdown
-            let res = run_cargo(cmd, &mut |message| {
-                // Skip certain kinds of messages to only spend time on what's useful
-                match &message {
-                    cargo_metadata::Message::CompilerArtifact(artifact) if artifact.fresh => {
-                        return true
-                    }
-                    cargo_metadata::Message::BuildScriptExecuted(_)
-                    | cargo_metadata::Message::Unknown => return true,
-                    _ => {}
-                }
-
-                // if the send channel was closed, we want to shutdown
-                message_send.send(message).is_ok()
-            });
-
-            if let Err(err) = res {
-                // FIXME: make the `message_send` to be `Sender<Result<CheckEvent, CargoError>>`
-                // to display user-caused misconfiguration errors instead of just logging them here
-                log::error!("Cargo watcher failed {:?}", err);
-            }
-        });
-        (message_recv, thread)
+        cmd
     }
 
     fn send(&self, check_task: Message) {
@@ -232,54 +212,104 @@ impl FlycheckActor {
     }
 }
 
-fn run_cargo(
-    mut command: Command,
-    on_message: &mut dyn FnMut(cargo_metadata::Message) -> bool,
-) -> io::Result<()> {
-    let mut child =
-        command.stdout(Stdio::piped()).stderr(Stdio::null()).stdin(Stdio::null()).spawn()?;
+struct CargoHandle {
+    child: JodChild,
+    #[allow(unused)]
+    thread: jod_thread::JoinHandle<io::Result<bool>>,
+    receiver: Receiver<cargo_metadata::Message>,
+}
 
-    // We manually read a line at a time, instead of using serde's
-    // stream deserializers, because the deserializer cannot recover
-    // from an error, resulting in it getting stuck, because we try to
-    // be resillient against failures.
-    //
-    // Because cargo only outputs one JSON object per line, we can
-    // simply skip a line if it doesn't parse, which just ignores any
-    // erroneus output.
-    let stdout = BufReader::new(child.stdout.take().unwrap());
-    let mut read_at_least_one_message = false;
-    for message in cargo_metadata::Message::parse_stream(stdout) {
-        let message = match message {
-            Ok(message) => message,
-            Err(err) => {
-                log::error!("Invalid json from cargo check, ignoring ({})", err);
-                continue;
-            }
-        };
+impl CargoHandle {
+    fn spawn(mut child: JodChild) -> CargoHandle {
+        let child_stdout = child.stdout.take().unwrap();
+        let (sender, receiver) = unbounded();
+        let actor = CargoActor::new(child_stdout, sender);
+        let thread = jod_thread::spawn(move || actor.run());
+        CargoHandle { child, thread, receiver }
+    }
+    fn join(mut self) -> io::Result<()> {
+        // It is okay to ignore the result, as it only errors if the process is already dead
+        let _ = self.child.kill();
+        let exit_status = self.child.wait()?;
+        let read_at_least_one_message = self.thread.join()?;
+        if !exit_status.success() && !read_at_least_one_message {
+            // FIXME: Read the stderr to display the reason, see `read2()` reference in PR comment:
+            // https://github.com/rust-analyzer/rust-analyzer/pull/3632#discussion_r395605298
+            return Err(io::Error::new(
+                io::ErrorKind::Other,
+                format!(
+                    "Cargo watcher failed,the command produced no valid metadata (exit code: {:?})",
+                    exit_status
+                ),
+            ));
+        }
+        Ok(())
+    }
+}
+
+struct CargoActor {
+    child_stdout: process::ChildStdout,
+    sender: Sender<cargo_metadata::Message>,
+}
+
+impl CargoActor {
+    fn new(
+        child_stdout: process::ChildStdout,
+        sender: Sender<cargo_metadata::Message>,
+    ) -> CargoActor {
+        CargoActor { child_stdout, sender }
+    }
+    fn run(self) -> io::Result<bool> {
+        // We manually read a line at a time, instead of using serde's
+        // stream deserializers, because the deserializer cannot recover
+        // from an error, resulting in it getting stuck, because we try to
+        // be resilient against failures.
+        //
+        // Because cargo only outputs one JSON object per line, we can
+        // simply skip a line if it doesn't parse, which just ignores any
+        // erroneus output.
+        let stdout = BufReader::new(self.child_stdout);
+        let mut read_at_least_one_message = false;
+        for message in cargo_metadata::Message::parse_stream(stdout) {
+            let message = match message {
+                Ok(message) => message,
+                Err(err) => {
+                    log::error!("Invalid json from cargo check, ignoring ({})", err);
+                    continue;
+                }
+            };
 
-        read_at_least_one_message = true;
+            read_at_least_one_message = true;
 
-        if !on_message(message) {
-            break;
+            // Skip certain kinds of messages to only spend time on what's useful
+            match &message {
+                cargo_metadata::Message::CompilerArtifact(artifact) if artifact.fresh => (),
+                cargo_metadata::Message::BuildScriptExecuted(_)
+                | cargo_metadata::Message::Unknown => (),
+                _ => self.sender.send(message).unwrap(),
+            }
         }
+        Ok(read_at_least_one_message)
     }
+}
 
-    // It is okay to ignore the result, as it only errors if the process is already dead
-    let _ = child.kill();
+struct JodChild(process::Child);
 
-    let exit_status = child.wait()?;
-    if !exit_status.success() && !read_at_least_one_message {
-        // FIXME: Read the stderr to display the reason, see `read2()` reference in PR comment:
-        // https://github.com/rust-analyzer/rust-analyzer/pull/3632#discussion_r395605298
-        return Err(io::Error::new(
-            io::ErrorKind::Other,
-            format!(
-                "the command produced no valid metadata (exit code: {:?}): {:?}",
-                exit_status, command
-            ),
-        ));
+impl ops::Deref for JodChild {
+    type Target = process::Child;
+    fn deref(&self) -> &process::Child {
+        &self.0
     }
+}
 
-    Ok(())
+impl ops::DerefMut for JodChild {
+    fn deref_mut(&mut self) -> &mut process::Child {
+        &mut self.0
+    }
+}
+
+impl Drop for JodChild {
+    fn drop(&mut self) {
+        let _ = self.0.kill();
+    }
 }