2 files changed, 130 insertions, 0 deletions
diff --git a/cli/ops/fs_events.rs b/cli/ops/fs_events.rs
new file mode 100644
index 000000000..471556b5a
--- /dev/null
+++ b/cli/ops/fs_events.rs
@@ -0,0 +1,129 @@
+// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
+use super::dispatch_json::{Deserialize, JsonOp, Value};
+use crate::deno_error::bad_resource;
+use crate::ops::json_op;
+use crate::state::State;
+use deno_core::*;
+use futures::future::poll_fn;
+use futures::future::FutureExt;
+use notify::event::Event as NotifyEvent;
+use notify::Error as NotifyError;
+use notify::EventKind;
+use notify::RecommendedWatcher;
+use notify::RecursiveMode;
+use notify::Watcher;
+use serde::Serialize;
+use std::convert::From;
+use std::path::PathBuf;
+use tokio::sync::mpsc;
+
+pub fn init(i: &mut Isolate, s: &State) {
+  i.register_op(
+    "fs_events_open",
+    s.core_op(json_op(s.stateful_op(op_fs_events_open))),
+  );
+  i.register_op(
+    "fs_events_poll",
+    s.core_op(json_op(s.stateful_op(op_fs_events_poll))),
+  );
+}
+
+struct FsEventsResource {
+  #[allow(unused)]
+  watcher: RecommendedWatcher,
+  receiver: mpsc::Receiver<Result<FsEvent, ErrBox>>,
+}
+
+/// Represents a file system event.
+///
+/// We do not use the event directly from the notify crate. We flatten
+/// the structure into this simpler structure. We want to only make it more
+/// complex as needed.
+///
+/// Feel free to expand this struct as long as you can add tests to demonstrate
+/// the complexity.
+#[derive(Serialize, Debug)]
+struct FsEvent {
+  kind: String,
+  paths: Vec<PathBuf>,
+}
+
+impl From<NotifyEvent> for FsEvent {
+  fn from(e: NotifyEvent) -> Self {
+    let kind = match e.kind {
+      EventKind::Any => "any",
+      EventKind::Access(_) => "access",
+      EventKind::Create(_) => "create",
+      EventKind::Modify(_) => "modify",
+      EventKind::Remove(_) => "remove",
+      EventKind::Other => todo!(), // What's this for? Leaving it out for now.
+    }
+    .to_string();
+    FsEvent {
+      kind,
+      paths: e.paths,
+    }
+  }
+}
+
+pub fn op_fs_events_open(
+  state: &State,
+  args: Value,
+  _zero_copy: Option<ZeroCopyBuf>,
+) -> Result<JsonOp, ErrBox> {
+  #[derive(Deserialize)]
+  struct OpenArgs {
+    recursive: bool,
+    paths: Vec<String>,
+  }
+  let args: OpenArgs = serde_json::from_value(args)?;
+  let (sender, receiver) = mpsc::channel::<Result<FsEvent, ErrBox>>(16);
+  let sender = std::sync::Mutex::new(sender);
+  let mut watcher: RecommendedWatcher =
+    Watcher::new_immediate(move |res: Result<NotifyEvent, NotifyError>| {
+      let res2 = res.map(FsEvent::from).map_err(ErrBox::from);
+      let mut sender = sender.lock().unwrap();
+      futures::executor::block_on(sender.send(res2)).expect("fs events error");
+    })?;
+  let recursive_mode = if args.recursive {
+    RecursiveMode::Recursive
+  } else {
+    RecursiveMode::NonRecursive
+  };
+  for path in &args.paths {
+    state.check_read(&PathBuf::from(path))?;
+    watcher.watch(path, recursive_mode)?;
+  }
+  let resource = FsEventsResource { watcher, receiver };
+  let table = &mut state.borrow_mut().resource_table;
+  let rid = table.add("fsEvents", Box::new(resource));
+  Ok(JsonOp::Sync(json!(rid)))
+}
+
+pub fn op_fs_events_poll(
+  state: &State,
+  args: Value,
+  _zero_copy: Option<ZeroCopyBuf>,
+) -> Result<JsonOp, ErrBox> {
+  #[derive(Deserialize)]
+  struct PollArgs {
+    rid: u32,
+  }
+  let PollArgs { rid } = serde_json::from_value(args)?;
+  let state = state.clone();
+  let f = poll_fn(move |cx| {
+    let resource_table = &mut state.borrow_mut().resource_table;
+    let watcher = resource_table
+      .get_mut::<FsEventsResource>(rid)
+      .ok_or_else(bad_resource)?;
+    watcher
+      .receiver
+      .poll_recv(cx)
+      .map(|maybe_result| match maybe_result {
+        Some(Ok(value)) => Ok(json!({ "value": value, "done": false })),
+        Some(Err(err)) => Err(err),
+        None => Ok(json!({ "done": true })),
+      })
+  });
+  Ok(JsonOp::Async(f.boxed_local()))
+}
diff --git a/cli/ops/mod.rs b/cli/ops/mod.rs
index dd772cd9a..7746143db 100644
--- a/cli/ops/mod.rs
+++ b/cli/ops/mod.rs
@@ -13,6 +13,7 @@ pub mod errors;
 pub mod fetch;
 pub mod files;
 pub mod fs;
+pub mod fs_events;
 pub mod io;
 pub mod net;
 pub mod os;