11 files changed, 291 insertions, 60 deletions

diff --git a/cli/fmt_errors.rs b/cli/fmt_errors.rs
index 83e417fe2..9979eeb29 100644
--- a/cli/fmt_errors.rs
+++ b/cli/fmt_errors.rs
@@ -151,6 +151,12 @@ impl JSError {
   }
 }
 
+impl Into<V8Exception> for JSError {
+  fn into(self) -> V8Exception {
+    self.0
+  }
+}
+
 impl DisplayFormatter for JSError {
   fn format_category_and_code(&self) -> String {
     "".to_string()
diff --git a/cli/js/dispatch.ts b/cli/js/dispatch.ts
index d658c5de7..7e6709dc6 100644
--- a/cli/js/dispatch.ts
+++ b/cli/js/dispatch.ts
@@ -42,8 +42,11 @@ export let OP_QUERY_PERMISSION: number;
 export let OP_REVOKE_PERMISSION: number;
 export let OP_REQUEST_PERMISSION: number;
 export let OP_CREATE_WORKER: number;
-export let OP_HOST_GET_WORKER_CLOSED: number;
+export let OP_HOST_GET_WORKER_LOADED: number;
 export let OP_HOST_POST_MESSAGE: number;
+export let OP_HOST_POLL_WORKER: number;
+export let OP_HOST_CLOSE_WORKER: number;
+export let OP_HOST_RESUME_WORKER: number;
 export let OP_HOST_GET_MESSAGE: number;
 export let OP_WORKER_POST_MESSAGE: number;
 export let OP_WORKER_GET_MESSAGE: number;
diff --git a/cli/js/globals.ts b/cli/js/globals.ts
index c7f3b23f2..f090afcd4 100644
--- a/cli/js/globals.ts
+++ b/cli/js/globals.ts
@@ -150,6 +150,7 @@ window.performance = new performanceUtil.Performance();
 // This variable functioning correctly depends on `declareAsLet`
 // in //tools/ts_library_builder/main.ts
 window.onmessage = workers.onmessage;
+window.onerror = workers.onerror;
 
 window.workerMain = workers.workerMain;
 window.workerClose = workers.workerClose;
diff --git a/cli/js/lib.deno_runtime.d.ts b/cli/js/lib.deno_runtime.d.ts
index 8740af062..109c0367d 100644
--- a/cli/js/lib.deno_runtime.d.ts
+++ b/cli/js/lib.deno_runtime.d.ts
@@ -1986,6 +1986,7 @@ declare interface Window {
   Response: typeof __fetch.Response;
   performance: __performanceUtil.Performance;
   onmessage: (e: { data: any }) => void;
+  onerror: undefined | typeof onerror;
   workerMain: typeof __workers.workerMain;
   workerClose: typeof __workers.workerClose;
   postMessage: typeof __workers.postMessage;
@@ -2036,6 +2037,7 @@ declare const Request: __domTypes.RequestConstructor;
 declare const Response: typeof __fetch.Response;
 declare const performance: __performanceUtil.Performance;
 declare let onmessage: (e: { data: any }) => void;
+declare let onerror: (e: Event) => void;
 declare const workerMain: typeof __workers.workerMain;
 declare const workerClose: typeof __workers.workerClose;
 declare const postMessage: typeof __workers.postMessage;
@@ -3293,7 +3295,7 @@ declare namespace __workers {
   export function workerClose(): void;
   export function workerMain(): Promise<void>;
   export interface Worker {
-    onerror?: () => void;
+    onerror?: (e: Event) => void;
     onmessage?: (e: { data: any }) => void;
     onmessageerror?: () => void;
     postMessage(data: any): void;
@@ -3311,7 +3313,7 @@ declare namespace __workers {
     private readonly id;
     private isClosing;
     private readonly isClosedPromise;
-    onerror?: () => void;
+    onerror?: (e: Event) => void;
     onmessage?: (data: any) => void;
     onmessageerror?: () => void;
     constructor(specifier: string, options?: DenoWorkerOptions);
diff --git a/cli/js/workers.ts b/cli/js/workers.ts
index 27f873100..d1d8f78e2 100644
--- a/cli/js/workers.ts
+++ b/cli/js/workers.ts
@@ -2,11 +2,12 @@
 /* eslint-disable @typescript-eslint/no-explicit-any */
 import * as dispatch from "./dispatch.ts";
 import { sendAsync, sendSync } from "./dispatch_json.ts";
-import { log } from "./util.ts";
+import { log, createResolvable, Resolvable } from "./util.ts";
 import { TextDecoder, TextEncoder } from "./text_encoding.ts";
 import { window } from "./window.ts";
 import { blobURLMap } from "./url.ts";
 import { blobBytesWeakMap } from "./blob.ts";
+import { EventTarget } from "./event_target.ts";
 
 const encoder = new TextEncoder();
 const decoder = new TextDecoder();
@@ -26,7 +27,7 @@ function createWorker(
   includeDenoNamespace: boolean,
   hasSourceCode: boolean,
   sourceCode: Uint8Array
-): number {
+): { id: number; loaded: boolean } {
   return sendSync(dispatch.OP_CREATE_WORKER, {
     specifier,
     includeDenoNamespace,
@@ -35,8 +36,20 @@ function createWorker(
   });
 }
 
-async function hostGetWorkerClosed(id: number): Promise<void> {
-  await sendAsync(dispatch.OP_HOST_GET_WORKER_CLOSED, { id });
+async function hostGetWorkerLoaded(id: number): Promise<any> {
+  return await sendAsync(dispatch.OP_HOST_GET_WORKER_LOADED, { id });
+}
+
+async function hostPollWorker(id: number): Promise<any> {
+  return await sendAsync(dispatch.OP_HOST_POLL_WORKER, { id });
+}
+
+function hostCloseWorker(id: number): void {
+  sendSync(dispatch.OP_HOST_CLOSE_WORKER, { id });
+}
+
+function hostResumeWorker(id: number): void {
+  sendSync(dispatch.OP_HOST_RESUME_WORKER, { id });
 }
 
 function hostPostMessage(id: number, data: any): void {
@@ -56,6 +69,7 @@ async function hostGetMessage(id: number): Promise<any> {
 
 // Stuff for workers
 export const onmessage: (e: { data: any }) => void = (): void => {};
+export const onerror: (e: { data: any }) => void = (): void => {};
 
 export function postMessage(data: any): void {
   const dataIntArray = encodeMessage(data);
@@ -88,25 +102,41 @@ export async function workerMain(): Promise<void> {
       break;
     }
 
-    if (window["onmessage"]) {
-      const event = { data };
-      const result: void | Promise<void> = window.onmessage(event);
+    let result: void | Promise<void>;
+    const event = { data };
+
+    try {
+      result = window.onmessage(event);
       if (result && "then" in result) {
         await result;
       }
-    }
-
-    if (!window["onmessage"]) {
-      break;
+      if (!window["onmessage"]) {
+        break;
+      }
+    } catch (e) {
+      if (window["onerror"]) {
+        const result = window.onerror(
+          e.message,
+          e.fileName,
+          e.lineNumber,
+          e.columnNumber,
+          e
+        );
+        if (result === true) {
+          continue;
+        }
+      }
+      throw e;
     }
   }
 }
 
 export interface Worker {
-  onerror?: () => void;
+  onerror?: (e: any) => void;
   onmessage?: (e: { data: any }) => void;
   onmessageerror?: () => void;
   postMessage(data: any): void;
+  // TODO(bartlomieju): remove this
   closed: Promise<void>;
 }
 
@@ -122,15 +152,18 @@ export interface DenoWorkerOptions extends WorkerOptions {
   noDenoNamespace?: boolean;
 }
 
-export class WorkerImpl implements Worker {
+export class WorkerImpl extends EventTarget implements Worker {
   private readonly id: number;
   private isClosing = false;
-  private readonly isClosedPromise: Promise<void>;
-  public onerror?: () => void;
+  private messageBuffer: any[] = [];
+  private ready = false;
+  private readonly isClosedPromise: Resolvable<void>;
+  public onerror?: (e: any) => void;
   public onmessage?: (data: any) => void;
   public onmessageerror?: () => void;
 
   constructor(specifier: string, options?: DenoWorkerOptions) {
+    super();
     let hasSourceCode = false;
     let sourceCode = new Uint8Array();
 
@@ -152,24 +185,87 @@ export class WorkerImpl implements Worker {
       sourceCode = blobBytes!;
     }
 
-    this.id = createWorker(
+    const { id, loaded } = createWorker(
       specifier,
       includeDenoNamespace,
       hasSourceCode,
       sourceCode
     );
-    this.run();
-    this.isClosedPromise = hostGetWorkerClosed(this.id);
-    this.isClosedPromise.then((): void => {
-      this.isClosing = true;
-    });
+    this.id = id;
+    this.ready = loaded;
+    this.isClosedPromise = createResolvable();
+    this.poll();
   }
 
   get closed(): Promise<void> {
     return this.isClosedPromise;
   }
 
+  private handleError(e: any): boolean {
+    const event = new window.Event("error", { cancelable: true });
+    event.message = e.message;
+    event.lineNumber = e.lineNumber ? e.lineNumber + 1 : null;
+    event.columnNumber = e.columnNumber ? e.columnNumber + 1 : null;
+    event.fileName = e.fileName;
+    event.error = null;
+
+    let handled = false;
+    if (this.onerror) {
+      this.onerror(event);
+      if (event.defaultPrevented) {
+        handled = true;
+      }
+    }
+
+    return handled;
+  }
+
+  async poll(): Promise<void> {
+    // If worker has not been immediately executed
+    // then let's await it's readiness
+    if (!this.ready) {
+      const result = await hostGetWorkerLoaded(this.id);
+
+      if (result.error) {
+        if (!this.handleError(result.error)) {
+          throw new Error(result.error.message);
+        }
+        return;
+      }
+    }
+
+    // drain messages
+    for (const data of this.messageBuffer) {
+      hostPostMessage(this.id, data);
+    }
+    this.messageBuffer = [];
+    this.ready = true;
+    this.run();
+
+    while (true) {
+      const result = await hostPollWorker(this.id);
+
+      if (result.error) {
+        if (!this.handleError(result.error)) {
+          throw Error(result.error.message);
+        } else {
+          hostResumeWorker(this.id);
+        }
+      } else {
+        this.isClosing = true;
+        hostCloseWorker(this.id);
+        this.isClosedPromise.resolve();
+        break;
+      }
+    }
+  }
+
   postMessage(data: any): void {
+    if (!this.ready) {
+      this.messageBuffer.push(data);
+      return;
+    }
+
     hostPostMessage(this.id, data);
   }
 
@@ -180,7 +276,6 @@ export class WorkerImpl implements Worker {
         log("worker got null message. quitting.");
         break;
       }
-      // TODO(afinch7) stop this from eating messages before onmessage has been assigned
       if (this.onmessage) {
         const event = { data };
         this.onmessage(event);
diff --git a/cli/ops/workers.rs b/cli/ops/workers.rs
index 6ebaa141f..eeffb3930 100644
--- a/cli/ops/workers.rs
+++ b/cli/ops/workers.rs
@@ -4,12 +4,15 @@ use crate::deno_error::bad_resource;
 use crate::deno_error::js_check;
 use crate::deno_error::DenoError;
 use crate::deno_error::ErrorKind;
+use crate::deno_error::GetErrorKind;
+use crate::fmt_errors::JSError;
 use crate::ops::json_op;
 use crate::startup_data;
 use crate::state::ThreadSafeState;
 use crate::worker::Worker;
 use deno_core::*;
 use futures;
+use futures::channel::mpsc;
 use futures::future::FutureExt;
 use futures::future::TryFutureExt;
 use futures::sink::SinkExt;
@@ -19,7 +22,6 @@ use std::convert::From;
 use std::future::Future;
 use std::pin::Pin;
 use std::sync::atomic::Ordering;
-use std::sync::mpsc;
 use std::task::Context;
 use std::task::Poll;
 
@@ -29,8 +31,20 @@ pub fn init(i: &mut Isolate, s: &ThreadSafeState) {
     s.core_op(json_op(s.stateful_op(op_create_worker))),
   );
   i.register_op(
-    "host_get_worker_closed",
-    s.core_op(json_op(s.stateful_op(op_host_get_worker_closed))),
+    "host_get_worker_loaded",
+    s.core_op(json_op(s.stateful_op(op_host_get_worker_loaded))),
+  );
+  i.register_op(
+    "host_poll_worker",
+    s.core_op(json_op(s.stateful_op(op_host_poll_worker))),
+  );
+  i.register_op(
+    "host_close_worker",
+    s.core_op(json_op(s.stateful_op(op_host_close_worker))),
+  );
+  i.register_op(
+    "host_resume_worker",
+    s.core_op(json_op(s.stateful_op(op_host_resume_worker))),
   );
   i.register_op(
     "host_post_message",
@@ -155,37 +169,36 @@ fn op_create_worker(
   js_check(worker.execute("workerMain()"));
 
   let worker_id = parent_state.add_child_worker(worker.clone());
-  let response = json!(worker_id);
 
   // Has provided source code, execute immediately.
   if has_source_code {
     js_check(worker.execute(&source_code));
-    return Ok(JsonOp::Sync(response));
+    return Ok(JsonOp::Sync(json!({"id": worker_id, "loaded": true})));
   }
 
-  // TODO(bartlomieju): this should spawn mod execution on separate tokio task
-  // and block on receving message on a channel or even use sync channel /shrug
-  let (sender, receiver) = mpsc::sync_channel::<Result<(), ErrBox>>(1);
+  let (mut sender, receiver) = mpsc::channel::<Result<(), ErrBox>>(1);
+
+  // TODO(bartlomieju): this future should be spawned on the separate thread,
+  // dedicated to that worker
   let fut = async move {
     let result = worker
       .execute_mod_async(&module_specifier, None, false)
       .await;
-    sender.send(result).expect("Failed to send message");
+    sender.send(result).await.expect("Failed to send message");
   }
   .boxed();
   tokio::spawn(fut);
-
-  let result = receiver.recv().expect("Failed to receive message");
-  result?;
-  Ok(JsonOp::Sync(response))
+  let mut table = state.loading_workers.lock().unwrap();
+  table.insert(worker_id, receiver);
+  Ok(JsonOp::Sync(json!({"id": worker_id, "loaded": false})))
 }
 
-struct GetWorkerClosedFuture {
+struct WorkerPollFuture {
   state: ThreadSafeState,
   rid: ResourceId,
 }
 
-impl Future for GetWorkerClosedFuture {
+impl Future for WorkerPollFuture {
   type Output = Result<(), ErrBox>;
 
   fn poll(self: Pin<&mut Self>, cx: &mut Context) -> Poll<Self::Output> {
@@ -203,39 +216,114 @@ impl Future for GetWorkerClosedFuture {
   }
 }
 
+fn serialize_worker_result(result: Result<(), ErrBox>) -> Value {
+  if let Err(error) = result {
+    match error.kind() {
+      ErrorKind::JSError => {
+        let error = error.downcast::<JSError>().unwrap();
+        let exception: V8Exception = error.into();
+        json!({"error": {
+          "message": exception.message,
+          "fileName": exception.script_resource_name,
+          "lineNumber": exception.line_number,
+          "columnNumber": exception.start_column,
+        }})
+      }
+      _ => json!({"error": {
+        "message": error.to_string(),
+      }}),
+    }
+  } else {
+    json!({"ok": true})
+  }
+}
+
 #[derive(Deserialize)]
-struct HostGetWorkerClosedArgs {
+struct WorkerArgs {
   id: i32,
 }
 
-/// Return when the worker closes
-fn op_host_get_worker_closed(
+fn op_host_get_worker_loaded(
+  state: &ThreadSafeState,
+  args: Value,
+  _data: Option<PinnedBuf>,
+) -> Result<JsonOp, ErrBox> {
+  let args: WorkerArgs = serde_json::from_value(args)?;
+  let id = args.id as u32;
+  let mut table = state.loading_workers.lock().unwrap();
+  let mut receiver = table.remove(&id).unwrap();
+
+  let op = async move {
+    let result = receiver.next().await.unwrap();
+    Ok(serialize_worker_result(result))
+  };
+
+  Ok(JsonOp::Async(op.boxed()))
+}
+
+fn op_host_poll_worker(
   state: &ThreadSafeState,
   args: Value,
   _data: Option<PinnedBuf>,
 ) -> Result<JsonOp, ErrBox> {
-  let args: HostGetWorkerClosedArgs = serde_json::from_value(args)?;
+  let args: WorkerArgs = serde_json::from_value(args)?;
   let id = args.id as u32;
   let state_ = state.clone();
 
-  let future = GetWorkerClosedFuture {
+  let future = WorkerPollFuture {
     state: state.clone(),
     rid: id,
   };
-  let op = future.then(move |_result| {
-    let mut workers_table = state_.workers.lock().unwrap();
-    let maybe_worker = workers_table.remove(&id);
-    if let Some(worker) = maybe_worker {
-      let mut channels = worker.state.worker_channels.lock().unwrap();
-      channels.sender.close_channel();
-      channels.receiver.close();
-    };
-    futures::future::ok(json!({}))
-  });
 
+  let op = async move {
+    let result = future.await;
+
+    if result.is_err() {
+      let mut workers_table = state_.workers.lock().unwrap();
+      let worker = workers_table.get_mut(&id).unwrap();
+      worker.clear_exception();
+    }
+
+    Ok(serialize_worker_result(result))
+  };
   Ok(JsonOp::Async(op.boxed()))
 }
 
+fn op_host_close_worker(
+  state: &ThreadSafeState,
+  args: Value,
+  _data: Option<PinnedBuf>,
+) -> Result<JsonOp, ErrBox> {
+  let args: WorkerArgs = serde_json::from_value(args)?;
+  let id = args.id as u32;
+  let state_ = state.clone();
+
+  let mut workers_table = state_.workers.lock().unwrap();
+  let maybe_worker = workers_table.remove(&id);
+  if let Some(worker) = maybe_worker {
+    let mut channels = worker.state.worker_channels.lock().unwrap();
+    channels.sender.close_channel();
+    channels.receiver.close();
+  };
+
+  Ok(JsonOp::Sync(json!({})))
+}
+
+fn op_host_resume_worker(
+  state: &ThreadSafeState,
+  args: Value,
+  _data: Option<PinnedBuf>,
+) -> Result<JsonOp, ErrBox> {
+  let args: WorkerArgs = serde_json::from_value(args)?;
+  let id = args.id as u32;
+  let state_ = state.clone();
+
+  let mut workers_table = state_.workers.lock().unwrap();
+  let worker = workers_table.get_mut(&id).unwrap();
+  js_check(worker.execute("workerMain()"));
+  Ok(JsonOp::Sync(json!({})))
+}
+
 #[derive(Deserialize)]
 struct HostGetMessageArgs {
   id: i32,
diff --git a/cli/state.rs b/cli/state.rs
index a4974958b..ed7b8e438 100644
--- a/cli/state.rs
+++ b/cli/state.rs
@@ -53,6 +53,7 @@ pub struct State {
   pub metrics: Metrics,
   pub global_timer: Mutex<GlobalTimer>,
   pub workers: Mutex<HashMap<u32, Worker>>,
+  pub loading_workers: Mutex<HashMap<u32, mpsc::Receiver<Result<(), ErrBox>>>>,
   pub next_worker_id: AtomicUsize,
   pub start_time: Instant,
   pub seeded_rng: Option<Mutex<StdRng>>,
@@ -248,6 +249,7 @@ impl ThreadSafeState {
       metrics: Metrics::default(),
       global_timer: Mutex::new(GlobalTimer::new()),
       workers: Mutex::new(HashMap::new()),
+      loading_workers: Mutex::new(HashMap::new()),
       next_worker_id: AtomicUsize::new(0),
       start_time: Instant::now(),
       seeded_rng,
diff --git a/cli/tests/026_workers.ts b/cli/tests/026_workers.ts
index f45fc4b77..7ac1a0f32 100644
--- a/cli/tests/026_workers.ts
+++ b/cli/tests/026_workers.ts
@@ -11,4 +11,10 @@ jsWorker.onmessage = (e): void => {
   tsWorker.postMessage("Hello World");
 };
 
+jsWorker.onerror = (e: Event): void => {
+  e.preventDefault();
+  console.log("called onerror in script");
+  jsWorker.postMessage("Hello World");
+};
+
 jsWorker.postMessage("Hello World");
diff --git a/cli/tests/026_workers.ts.out b/cli/tests/026_workers.ts.out
index 7538cc867..92f7550ad 100644
--- a/cli/tests/026_workers.ts.out
+++ b/cli/tests/026_workers.ts.out
@@ -1,4 +1,7 @@
 Hello World
+called onerror in worker
+called onerror in script
+Hello World
 Received js: Hello World
 Hello World
 Received ts: Hello World
diff --git a/cli/tests/subdir/test_worker.js b/cli/tests/subdir/test_worker.js
index 53d38ba96..cec5bdf9b 100644
--- a/cli/tests/subdir/test_worker.js
+++ b/cli/tests/subdir/test_worker.js
@@ -1,7 +1,19 @@
+let thrown = false;
+
 onmessage = function(e) {
   console.log(e.data);
 
+  if (thrown === false) {
+    thrown = true;
+    throw new SyntaxError("[test error]");
+  }
+
   postMessage(e.data);
 
   workerClose();
 };
+
+onerror = function() {
+  console.log("called onerror in worker");
+  return false;
+};
diff --git a/cli/worker.rs b/cli/worker.rs
index 2b335127f..7faf17e60 100644
--- a/cli/worker.rs
+++ b/cli/worker.rs
@@ -12,6 +12,7 @@ use futures::future::FutureExt;
 use futures::future::TryFutureExt;
 use futures::sink::SinkExt;
 use futures::stream::StreamExt;
+use futures::task::AtomicWaker;
 use std::env;
 use std::future::Future;
 use std::pin::Pin;
@@ -159,6 +160,11 @@ impl Worker {
       channels: self.external_channels.clone(),
     }
   }
+
+  pub fn clear_exception(&mut self) {
+    let mut isolate = self.isolate.try_lock().unwrap();
+    isolate.clear_exception();
+  }
 }
 
 impl Future for Worker {
@@ -166,8 +172,15 @@ impl Future for Worker {
 
   fn poll(self: Pin<&mut Self>, cx: &mut Context) -> Poll<Self::Output> {
     let inner = self.get_mut();
-    let mut isolate = inner.isolate.try_lock().unwrap();
-    isolate.poll_unpin(cx)
+    let waker = AtomicWaker::new();
+    waker.register(cx.waker());
+    match inner.isolate.try_lock() {
+      Ok(mut isolate) => isolate.poll_unpin(cx),
+      Err(_) => {
+        waker.wake();
+        Poll::Pending
+      }
+    }
   }
 }
 
@@ -436,7 +449,7 @@ mod tests {
 
       let worker_ = worker.clone();
       let worker_future = async move {
-        let result = worker.await;
+        let result = worker_.await;
         println!("workers.rs after resource close");
         result.unwrap();
       }
@@ -446,10 +459,10 @@ mod tests {
       tokio::spawn(worker_future_);
 
       let msg = json!("hi").to_string().into_boxed_str().into_boxed_bytes();
-      let r = block_on(worker_.post_message(msg));
+      let r = block_on(worker.post_message(msg));
       assert!(r.is_ok());
 
-      block_on(worker_future);
+      block_on(worker_future)
     })
   }