3 files changed, 99 insertions, 66 deletions

diff --git a/crates/ra_vfs/Cargo.toml b/crates/ra_vfs/Cargo.toml
index 2fe3102ab..fdaf31b9c 100644
--- a/crates/ra_vfs/Cargo.toml
+++ b/crates/ra_vfs/Cargo.toml
@@ -13,8 +13,6 @@ log = "0.4.6"
 notify = "4.0.9"
 parking_lot = "0.7.0"
 
-thread_worker = { path = "../thread_worker" }
-
 [dev-dependencies]
 tempfile = "3"
 flexi_logger = "0.10.0"
diff --git a/crates/ra_vfs/src/io.rs b/crates/ra_vfs/src/io.rs
index 8eb148a38..b6a057697 100644
--- a/crates/ra_vfs/src/io.rs
+++ b/crates/ra_vfs/src/io.rs
@@ -3,8 +3,9 @@ use std::{
     path::{Path, PathBuf},
     sync::{mpsc, Arc},
     time::Duration,
+    thread,
 };
-use crossbeam_channel::{Sender, unbounded, RecvError, select};
+use crossbeam_channel::{Sender, Receiver, unbounded, RecvError, select};
 use relative_path::RelativePathBuf;
 use walkdir::WalkDir;
 use notify::{DebouncedEvent, RecommendedWatcher, RecursiveMode, Watcher as _Watcher};
@@ -46,7 +47,40 @@ enum ChangeKind {
 
 const WATCHER_DELAY: Duration = Duration::from_millis(250);
 
-pub(crate) type Worker = thread_worker::Worker<Task, VfsTask>;
+// Like thread::JoinHandle, but joins the thread on drop.
+//
+// This is useful because it guarantees the absence of run-away threads, even if
+// code panics. This is important, because we might seem panics in the test and
+// we might be used in an IDE context, where a failed component is just
+// restarted.
+//
+// Because all threads are joined, care must be taken to avoid deadlocks. That
+// typically means ensuring that channels are dropped before the threads.
+struct ScopedThread(Option<thread::JoinHandle<()>>);
+
+impl ScopedThread {
+    fn spawn(name: String, f: impl FnOnce() + Send + 'static) -> ScopedThread {
+        let handle = thread::Builder::new().name(name).spawn(f).unwrap();
+        ScopedThread(Some(handle))
+    }
+}
+
+impl Drop for ScopedThread {
+    fn drop(&mut self) {
+        let res = self.0.take().unwrap().join();
+        if !thread::panicking() {
+            res.unwrap();
+        }
+    }
+}
+
+pub(crate) struct Worker {
+    // XXX: it's important to drop `sender` before `_thread` to avoid deadlock.
+    pub(crate) sender: Sender<Task>,
+    _thread: ScopedThread,
+    pub(crate) receiver: Receiver<VfsTask>,
+}
+
 pub(crate) fn start(roots: Arc<Roots>) -> Worker {
     // This is a pretty elaborate setup of threads & channels! It is
     // explained by the following concerns:
@@ -55,69 +89,70 @@ pub(crate) fn start(roots: Arc<Roots>) -> Worker {
     //    * we want to read all files from a single thread, to guarantee that
     //      we always get fresher versions and never go back in time.
     //    * we want to tear down everything neatly during shutdown.
-    Worker::spawn(
-        "vfs",
-        128,
-        // This are the channels we use to communicate with outside world.
-        // If `input_receiver` is closed we need to tear ourselves down.
-        // `output_sender` should not be closed unless the parent died.
-        move |input_receiver, output_sender| {
-            // Make sure that the destruction order is
-            //
-            // * notify_sender
-            // * _thread
-            // * watcher_sender
-            //
-            // this is required to avoid deadlocks.
-
-            // These are the corresponding crossbeam channels
-            let (watcher_sender, watcher_receiver) = unbounded();
-            let _thread;
-            {
-                // These are `std` channels notify will send events to
-                let (notify_sender, notify_receiver) = mpsc::channel();
-
-                let mut watcher = notify::watcher(notify_sender, WATCHER_DELAY)
-                    .map_err(|e| log::error!("failed to spawn notify {}", e))
-                    .ok();
-                // Start a silly thread to transform between two channels
-                _thread = thread_worker::ScopedThread::spawn("notify-convertor", move || {
-                    notify_receiver
-                        .into_iter()
-                        .for_each(|event| convert_notify_event(event, &watcher_sender))
-                });
-
-                // Process requests from the called or notifications from
-                // watcher until the caller says stop.
-                loop {
-                    select! {
-                        // Received request from the caller. If this channel is
-                        // closed, we should shutdown everything.
-                        recv(input_receiver) -> t => match t {
-                            Err(RecvError) => {
-                                drop(input_receiver);
-                                break
-                            },
-                            Ok(Task::AddRoot { root }) => {
-                                watch_root(watcher.as_mut(), &output_sender, &*roots, root);
-                            }
-                        },
-                        // Watcher send us changes. If **this** channel is
-                        // closed, the watcher has died, which indicates a bug
-                        // -- escalate!
-                        recv(watcher_receiver) -> event => match event {
-                            Err(RecvError) => panic!("watcher is dead"),
-                            Ok((path, change)) => {
-                                handle_change(watcher.as_mut(), &output_sender, &*roots, path, change);
-                            }
+    let _thread;
+    // This are the channels we use to communicate with outside world.
+    // If `input_receiver` is closed we need to tear ourselves down.
+    // `output_sender` should not be closed unless the parent died.
+    let (input_sender, input_receiver) = unbounded();
+    let (output_sender, output_receiver) = unbounded();
+
+    _thread = ScopedThread::spawn("vfs".to_string(), move || {
+        // Make sure that the destruction order is
+        //
+        // * notify_sender
+        // * _thread
+        // * watcher_sender
+        //
+        // this is required to avoid deadlocks.
+
+        // These are the corresponding crossbeam channels
+        let (watcher_sender, watcher_receiver) = unbounded();
+        let _notify_thread;
+        {
+            // These are `std` channels notify will send events to
+            let (notify_sender, notify_receiver) = mpsc::channel();
+
+            let mut watcher = notify::watcher(notify_sender, WATCHER_DELAY)
+                .map_err(|e| log::error!("failed to spawn notify {}", e))
+                .ok();
+            // Start a silly thread to transform between two channels
+            _notify_thread = ScopedThread::spawn("notify-convertor".to_string(), move || {
+                notify_receiver
+                    .into_iter()
+                    .for_each(|event| convert_notify_event(event, &watcher_sender))
+            });
+
+            // Process requests from the called or notifications from
+            // watcher until the caller says stop.
+            loop {
+                select! {
+                    // Received request from the caller. If this channel is
+                    // closed, we should shutdown everything.
+                    recv(input_receiver) -> t => match t {
+                        Err(RecvError) => {
+                            drop(input_receiver);
+                            break
                         },
-                    }
+                        Ok(Task::AddRoot { root }) => {
+                            watch_root(watcher.as_mut(), &output_sender, &*roots, root);
+                        }
+                    },
+                    // Watcher send us changes. If **this** channel is
+                    // closed, the watcher has died, which indicates a bug
+                    // -- escalate!
+                    recv(watcher_receiver) -> event => match event {
+                        Err(RecvError) => panic!("watcher is dead"),
+                        Ok((path, change)) => {
+                            handle_change(watcher.as_mut(), &output_sender, &*roots, path, change);
+                        }
+                    },
                 }
             }
-            // Drain pending events: we are not interested in them anyways!
-            watcher_receiver.into_iter().for_each(|_| ());
-        },
-    )
+        }
+        // Drain pending events: we are not interested in them anyways!
+        watcher_receiver.into_iter().for_each(|_| ());
+    });
+    Worker { sender: input_sender, _thread, receiver: output_receiver }
 }
 
 fn watch_root(
diff --git a/crates/ra_vfs/src/lib.rs b/crates/ra_vfs/src/lib.rs
index 3cd11c9f6..808c138df 100644
--- a/crates/ra_vfs/src/lib.rs
+++ b/crates/ra_vfs/src/lib.rs
@@ -92,7 +92,7 @@ impl Vfs {
 
         for root in roots.iter() {
             root2files.insert(root, Default::default());
-            worker.sender().send(io::Task::AddRoot { root }).unwrap();
+            worker.sender.send(io::Task::AddRoot { root }).unwrap();
         }
         let res = Vfs { roots, files: Vec::new(), root2files, worker, pending_changes: Vec::new() };
         let vfs_roots = res.roots.iter().collect();
@@ -170,7 +170,7 @@ impl Vfs {
     }
 
     pub fn task_receiver(&self) -> &Receiver<VfsTask> {
-        self.worker.receiver()
+        &self.worker.receiver
     }
 
     pub fn handle_task(&mut self, task: VfsTask) {