1 files changed, 128 insertions, 0 deletions

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
+    }
+}