2 files changed, 340 insertions, 0 deletions

diff --git a/crates/ra_vfs/src/io/mod.rs b/crates/ra_vfs/src/io/mod.rs
new file mode 100644
index 000000000..6d5af7690
--- /dev/null
+++ b/crates/ra_vfs/src/io/mod.rs
@@ -0,0 +1,212 @@
+use std::{
+    fmt, fs,
+    path::{Path, PathBuf},
+    sync::Arc,
+    thread,
+};
+
+use crossbeam_channel::{Receiver, Sender};
+use parking_lot::Mutex;
+use relative_path::RelativePathBuf;
+use thread_worker::WorkerHandle;
+use walkdir::{DirEntry, WalkDir};
+
+mod watcher;
+use watcher::Watcher;
+pub use watcher::WatcherChange;
+
+use crate::VfsRoot;
+
+pub(crate) enum Task {
+    AddRoot {
+        root: VfsRoot,
+        path: PathBuf,
+        filter: Box<Fn(&DirEntry) -> bool + Send>,
+    },
+    /// this variant should only be created by the watcher
+    HandleChange(WatcherChange),
+    LoadChange(WatcherChange),
+    Watch {
+        dir: PathBuf,
+        filter: Box<Fn(&DirEntry) -> bool + Send>,
+    },
+}
+
+#[derive(Debug)]
+pub struct AddRootResult {
+    pub(crate) root: VfsRoot,
+    pub(crate) files: Vec<(RelativePathBuf, String)>,
+}
+
+#[derive(Debug)]
+pub enum WatcherChangeData {
+    Create { path: PathBuf, text: String },
+    Write { path: PathBuf, text: String },
+    Remove { path: PathBuf },
+}
+
+pub enum TaskResult {
+    AddRoot(AddRootResult),
+    HandleChange(WatcherChange),
+    LoadChange(WatcherChangeData),
+    NoOp,
+}
+
+impl fmt::Debug for TaskResult {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        f.write_str("TaskResult { ... }")
+    }
+}
+
+pub(crate) struct Worker {
+    worker: thread_worker::Worker<Task, TaskResult>,
+    worker_handle: WorkerHandle,
+    watcher: Arc<Mutex<Option<Watcher>>>,
+}
+
+impl Worker {
+    pub(crate) fn start() -> Worker {
+        let watcher = Arc::new(Mutex::new(None));
+        let watcher_clone = watcher.clone();
+        let (worker, worker_handle) =
+            thread_worker::spawn("vfs", 128, move |input_receiver, output_sender| {
+                input_receiver
+                    .into_iter()
+                    .map(|t| handle_task(t, &watcher_clone))
+                    .try_for_each(|it| output_sender.send(it))
+                    .unwrap()
+            });
+        match Watcher::start(worker.inp.clone()) {
+            Ok(w) => {
+                watcher.lock().replace(w);
+            }
+            Err(e) => log::error!("could not start watcher: {}", e),
+        };
+        Worker {
+            worker,
+            worker_handle,
+            watcher,
+        }
+    }
+
+    pub(crate) fn sender(&self) -> &Sender<Task> {
+        &self.worker.inp
+    }
+
+    pub(crate) fn receiver(&self) -> &Receiver<TaskResult> {
+        &self.worker.out
+    }
+
+    pub(crate) fn shutdown(self) -> thread::Result<()> {
+        if let Some(watcher) = self.watcher.lock().take() {
+            let _ = watcher.shutdown();
+        }
+        let _ = self.worker.shutdown();
+        self.worker_handle.shutdown()
+    }
+}
+
+fn watch(
+    watcher: &Arc<Mutex<Option<Watcher>>>,
+    dir: &Path,
+    filter_entry: impl Fn(&DirEntry) -> bool,
+    emit_for_existing: bool,
+) {
+    let mut watcher = watcher.lock();
+    let watcher = match *watcher {
+        Some(ref mut w) => w,
+        None => {
+            // watcher dropped or couldn't start
+            return;
+        }
+    };
+    watcher.watch_recursive(dir, filter_entry, emit_for_existing)
+}
+
+fn handle_task(task: Task, watcher: &Arc<Mutex<Option<Watcher>>>) -> TaskResult {
+    match task {
+        Task::AddRoot { root, path, filter } => {
+            watch(watcher, &path, &*filter, false);
+            log::debug!("loading {} ...", path.as_path().display());
+            let files = load_root(path.as_path(), &*filter);
+            log::debug!("... loaded {}", path.as_path().display());
+            TaskResult::AddRoot(AddRootResult { root, files })
+        }
+        Task::HandleChange(change) => {
+            // forward as is because Vfs has to decide if we should load it
+            TaskResult::HandleChange(change)
+        }
+        Task::LoadChange(change) => {
+            log::debug!("loading {:?} ...", change);
+            match load_change(change) {
+                Some(data) => TaskResult::LoadChange(data),
+                None => TaskResult::NoOp,
+            }
+        }
+        Task::Watch { dir, filter } => {
+            watch(watcher, &dir, &*filter, true);
+            TaskResult::NoOp
+        }
+    }
+}
+
+fn load_root(root: &Path, filter: &dyn Fn(&DirEntry) -> bool) -> Vec<(RelativePathBuf, String)> {
+    let mut res = Vec::new();
+    for entry in WalkDir::new(root).into_iter().filter_entry(filter) {
+        let entry = match entry {
+            Ok(entry) => entry,
+            Err(e) => {
+                log::warn!("watcher error: {}", e);
+                continue;
+            }
+        };
+        if !entry.file_type().is_file() {
+            continue;
+        }
+        let path = entry.path();
+        let text = match fs::read_to_string(path) {
+            Ok(text) => text,
+            Err(e) => {
+                log::warn!("watcher error: {}", e);
+                continue;
+            }
+        };
+        let path = RelativePathBuf::from_path(path.strip_prefix(root).unwrap()).unwrap();
+        res.push((path.to_owned(), text))
+    }
+    res
+}
+
+fn load_change(change: WatcherChange) -> Option<WatcherChangeData> {
+    let data = match change {
+        WatcherChange::Create(path) => {
+            if path.is_dir() {
+                return None;
+            }
+            let text = match fs::read_to_string(&path) {
+                Ok(text) => text,
+                Err(e) => {
+                    log::warn!("watcher error \"{}\": {}", path.display(), e);
+                    return None;
+                }
+            };
+            WatcherChangeData::Create { path, text }
+        }
+        WatcherChange::Write(path) => {
+            let text = match fs::read_to_string(&path) {
+                Ok(text) => text,
+                Err(e) => {
+                    log::warn!("watcher error \"{}\": {}", path.display(), e);
+                    return None;
+                }
+            };
+            WatcherChangeData::Write { path, text }
+        }
+        WatcherChange::Remove(path) => WatcherChangeData::Remove { path },
+        WatcherChange::Rescan => {
+            // this should be handled by Vfs::handle_task
+            return None;
+        }
+    };
+    Some(data)
+}
diff --git a/crates/ra_vfs/src/io/watcher.rs b/crates/ra_vfs/src/io/watcher.rs
new file mode 100644
index 000000000..e33298477
--- /dev/null
+++ b/crates/ra_vfs/src/io/watcher.rs
@@ -0,0 +1,128 @@
+use crate::io;
+use crossbeam_channel::Sender;
+use drop_bomb::DropBomb;
+use notify::{DebouncedEvent, RecommendedWatcher, RecursiveMode, Watcher as NotifyWatcher};
+use std::{
+    path::{Path, PathBuf},
+    sync::mpsc,
+    thread,
+    time::Duration,
+};
+use walkdir::{DirEntry, WalkDir};
+
+#[derive(Debug)]
+pub enum WatcherChange {
+    Create(PathBuf),
+    Write(PathBuf),
+    Remove(PathBuf),
+    Rescan,
+}
+
+fn handle_change_event(
+    ev: DebouncedEvent,
+    sender: &Sender<io::Task>,
+) -> Result<(), Box<std::error::Error>> {
+    match ev {
+        DebouncedEvent::NoticeWrite(_)
+        | DebouncedEvent::NoticeRemove(_)
+        | DebouncedEvent::Chmod(_) => {
+            // ignore
+        }
+        DebouncedEvent::Rescan => {
+            sender.send(io::Task::HandleChange(WatcherChange::Rescan))?;
+        }
+        DebouncedEvent::Create(path) => {
+            sender.send(io::Task::HandleChange(WatcherChange::Create(path)))?;
+        }
+        DebouncedEvent::Write(path) => {
+            sender.send(io::Task::HandleChange(WatcherChange::Write(path)))?;
+        }
+        DebouncedEvent::Remove(path) => {
+            sender.send(io::Task::HandleChange(WatcherChange::Remove(path)))?;
+        }
+        DebouncedEvent::Rename(src, dst) => {
+            sender.send(io::Task::HandleChange(WatcherChange::Remove(src)))?;
+            sender.send(io::Task::HandleChange(WatcherChange::Create(dst)))?;
+        }
+        DebouncedEvent::Error(err, path) => {
+            // TODO should we reload the file contents?
+            log::warn!("watcher error \"{}\", {:?}", err, path);
+        }
+    }
+    Ok(())
+}
+
+const WATCHER_DELAY: Duration = Duration::from_millis(250);
+
+pub(crate) struct Watcher {
+    watcher: RecommendedWatcher,
+    thread: thread::JoinHandle<()>,
+    bomb: DropBomb,
+    sender: Sender<io::Task>,
+}
+
+impl Watcher {
+    pub(crate) fn start(
+        output_sender: Sender<io::Task>,
+    ) -> Result<Watcher, Box<std::error::Error>> {
+        let (input_sender, input_receiver) = mpsc::channel();
+        let watcher = notify::watcher(input_sender, WATCHER_DELAY)?;
+        let sender = output_sender.clone();
+        let thread = thread::spawn(move || {
+            input_receiver
+                .into_iter()
+                // forward relevant events only
+                .try_for_each(|change| handle_change_event(change, &output_sender))
+                .unwrap()
+        });
+        Ok(Watcher {
+            watcher,
+            thread,
+            sender,
+            bomb: DropBomb::new(format!("Watcher was not shutdown")),
+        })
+    }
+
+    pub fn watch_recursive(
+        &mut self,
+        dir: &Path,
+        filter_entry: impl Fn(&DirEntry) -> bool,
+        emit_for_contents: bool,
+    ) {
+        for res in WalkDir::new(dir).into_iter().filter_entry(filter_entry) {
+            match res {
+                Ok(entry) => {
+                    if entry.path().is_dir() {
+                        match self.watcher.watch(dir, RecursiveMode::NonRecursive) {
+                            Ok(()) => log::debug!("watching \"{}\"", dir.display()),
+                            Err(e) => log::warn!("could not watch \"{}\": {}", dir.display(), e),
+                        }
+                    }
+                    if emit_for_contents && entry.depth() > 0 {
+                        // emit as create because we haven't seen it yet
+                        if let Err(e) =
+                            self.sender
+                                .send(io::Task::HandleChange(WatcherChange::Create(
+                                    entry.path().to_path_buf(),
+                                )))
+                        {
+                            log::warn!("watcher error: {}", e)
+                        }
+                    }
+                }
+                Err(e) => log::warn!("watcher error: {}", e),
+            }
+        }
+    }
+
+    pub fn shutdown(mut self) -> thread::Result<()> {
+        self.bomb.defuse();
+        drop(self.watcher);
+        let res = self.thread.join();
+        match &res {
+            Ok(()) => log::info!("... Watcher terminated with ok"),
+            Err(_) => log::error!("... Watcher terminated with err"),
+        }
+        res
+    }
+}