refactor(cli): reorganize main.rs and split workers (#8495)

Factored out "init_v8_flags", "init_logger" and 
"get_subcommand" from "main" function.

Also "Worker" was removed in favor of moving 
logic to "MainWorker" and "WebWorker" respectively.

cli/main.rs

@@ -45,6 +45,7 @@ mod tools;
 mod tsc;
 mod tsc_config;
 mod version;
+mod web_worker;
 mod worker;
 
 use crate::file_fetcher::File;
@@ -792,14 +793,7 @@ async fn test_command(
   Ok(())
 }
 
-pub fn main() {
+fn init_v8_flags(v8_flags: &[String]) {
-  #[cfg(windows)]
-  colors::enable_ansi(); // For Windows 10
-
-  let args: Vec<String> = env::args().collect();
-  let flags = flags::flags_from_vec(args);
-
-  if let Some(ref v8_flags) = flags.v8_flags {
   let v8_flags_includes_help = v8_flags
     .iter()
     .any(|flag| flag == "-help" || flag == "--help");
@@ -822,7 +816,8 @@ pub fn main() {
   }
 }
 
-  let log_level = match flags.log_level {
+fn init_logger(maybe_level: Option<Level>) {
+  let log_level = match maybe_level {
     Some(level) => level,
     None => Level::Info, // Default log level
   };
@@ -853,8 +848,12 @@ pub fn main() {
     }
   })
   .init();
+}
 
-  let fut = match flags.clone().subcommand {
+fn get_subcommand(
+  flags: Flags,
+) -> Pin<Box<dyn Future<Output = Result<(), AnyError>>>> {
+  match flags.clone().subcommand {
     DenoSubcommand::Bundle {
       source_file,
       out_file,
@@ -914,7 +913,7 @@ pub fn main() {
         eprintln!("{}", e);
         std::process::exit(1);
       }
-      return;
+      std::process::exit(0);
     }
     DenoSubcommand::Types => {
       let types = get_types(flags.unstable);
@@ -922,7 +921,7 @@ pub fn main() {
         eprintln!("{}", e);
         std::process::exit(1);
       }
-      return;
+      std::process::exit(0);
     }
     DenoSubcommand::Upgrade {
       force,
@@ -934,9 +933,23 @@ pub fn main() {
       tools::upgrade::upgrade_command(dry_run, force, version, output, ca_file)
         .boxed_local()
     }
-  };
+  }
+}
 
-  let result = tokio_util::run_basic(fut);
+pub fn main() {
+  #[cfg(windows)]
+  colors::enable_ansi(); // For Windows 10
+
+  let args: Vec<String> = env::args().collect();
+  let flags = flags::flags_from_vec(args);
+
+  if let Some(ref v8_flags) = flags.v8_flags {
+    init_v8_flags(v8_flags);
+  }
+  init_logger(flags.log_level);
+
+  let subcommand_future = get_subcommand(flags);
+  let result = tokio_util::run_basic(subcommand_future);
   if let Err(err) = result {
     eprintln!("{}: {}", colors::red_bold("error"), err.to_string());
     std::process::exit(1);

cli/ops/web_worker.rs

@@ -1,7 +1,7 @@
 // Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
 
-use crate::worker::WebWorkerHandle;
+use crate::web_worker::WebWorkerHandle;
-use crate::worker::WorkerEvent;
+use crate::web_worker::WorkerEvent;
 use deno_core::futures::channel::mpsc;
 use deno_core::serde_json::json;
 

cli/ops/worker_host.rs

@@ -5,9 +5,9 @@ use crate::ops::io::get_stdio;
 use crate::permissions::Permissions;
 use crate::program_state::ProgramState;
 use crate::tokio_util::create_basic_runtime;
-use crate::worker::WebWorker;
+use crate::web_worker::WebWorker;
-use crate::worker::WebWorkerHandle;
+use crate::web_worker::WebWorkerHandle;
-use crate::worker::WorkerEvent;
+use crate::web_worker::WorkerEvent;
 use deno_core::error::generic_error;
 use deno_core::error::AnyError;
 use deno_core::error::JsError;

cli/tools/repl.rs

@@ -4,7 +4,6 @@ use crate::colors;
 use crate::inspector::InspectorSession;
 use crate::program_state::ProgramState;
 use crate::worker::MainWorker;
-use crate::worker::Worker;
 use deno_core::error::AnyError;
 use deno_core::serde_json::json;
 use deno_core::serde_json::Value;
@@ -280,7 +279,7 @@ impl Highlighter for LineHighlighter {
 }
 
 async fn post_message_and_poll(
-  worker: &mut Worker,
+  worker: &mut MainWorker,
   session: &mut InspectorSession,
   method: &str,
   params: Option<Value>,
@@ -305,7 +304,7 @@ async fn post_message_and_poll(
 }
 
 async fn read_line_and_poll(
-  worker: &mut Worker,
+  worker: &mut MainWorker,
   session: &mut InspectorSession,
   message_rx: &Receiver<(String, Option<Value>)>,
   response_tx: &Sender<Result<Value, AnyError>>,
@@ -425,7 +424,7 @@ pub async fn run(
 
   let history_file = program_state.dir.root.join("deno_history.txt");
 
-  post_message_and_poll(&mut *worker, &mut session, "Runtime.enable", None)
+  post_message_and_poll(&mut worker, &mut session, "Runtime.enable", None)
     .await?;
 
   // Enabling the runtime domain will always send trigger one executionContextCreated for each
@@ -474,7 +473,7 @@ pub async fn run(
 
   while !is_closing(&mut worker, &mut session, context_id).await? {
     let line = read_line_and_poll(
-      &mut *worker,
+      &mut worker,
       &mut session,
       &message_rx,
       &response_tx,
@@ -495,7 +494,7 @@ pub async fn run(
         };
 
         let evaluate_response = post_message_and_poll(
-          &mut *worker,
+          &mut worker,
           &mut session,
           "Runtime.evaluate",
           Some(json!({
@@ -513,7 +512,7 @@ pub async fn run(
             && wrapped_line != line
           {
             post_message_and_poll(
-              &mut *worker,
+              &mut worker,
               &mut session,
               "Runtime.evaluate",
               Some(json!({
@@ -533,7 +532,7 @@ pub async fn run(
 
         if evaluate_exception_details.is_some() {
           post_message_and_poll(
-                    &mut *worker,
+                    &mut worker,
                     &mut session,
                     "Runtime.callFunctionOn",
                     Some(json!({
@@ -546,7 +545,7 @@ pub async fn run(
                   ).await?;
         } else {
           post_message_and_poll(
-                    &mut *worker,
+                    &mut worker,
                     &mut session,
                     "Runtime.callFunctionOn",
                     Some(json!({
@@ -564,7 +563,7 @@ pub async fn run(
         // Deno.inspectArgs.
         let inspect_response =
           post_message_and_poll(
-            &mut *worker,
+            &mut worker,
             &mut session,
             "Runtime.callFunctionOn",
             Some(json!({

cli/web_worker.rs

@@ -0,0 +1,454 @@
+// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
+
+use crate::colors;
+use crate::fmt_errors::PrettyJsError;
+use crate::inspector::DenoInspector;
+use crate::js;
+use crate::metrics::Metrics;
+use crate::module_loader::CliModuleLoader;
+use crate::ops;
+use crate::permissions::Permissions;
+use crate::program_state::ProgramState;
+use crate::source_maps::apply_source_map;
+use deno_core::error::AnyError;
+use deno_core::futures::channel::mpsc;
+use deno_core::futures::future::poll_fn;
+use deno_core::futures::future::FutureExt;
+use deno_core::futures::stream::StreamExt;
+use deno_core::futures::task::AtomicWaker;
+use deno_core::url::Url;
+use deno_core::v8;
+use deno_core::JsRuntime;
+use deno_core::ModuleSpecifier;
+use deno_core::RuntimeOptions;
+use std::env;
+use std::sync::atomic::AtomicBool;
+use std::sync::atomic::Ordering;
+use std::sync::Arc;
+use std::task::Context;
+use std::task::Poll;
+use tokio::sync::Mutex as AsyncMutex;
+
+/// Events that are sent to host from child
+/// worker.
+pub enum WorkerEvent {
+  Message(Box<[u8]>),
+  Error(AnyError),
+  TerminalError(AnyError),
+}
+
+pub struct WorkerChannelsInternal {
+  pub sender: mpsc::Sender<WorkerEvent>,
+  pub receiver: mpsc::Receiver<Box<[u8]>>,
+}
+
+/// Wrapper for `WorkerHandle` that adds functionality
+/// for terminating workers.
+///
+/// This struct is used by host as well as worker itself.
+///
+/// Host uses it to communicate with worker and terminate it,
+/// while worker uses it only to finish execution on `self.close()`.
+#[derive(Clone)]
+pub struct WebWorkerHandle {
+  pub sender: mpsc::Sender<Box<[u8]>>,
+  pub receiver: Arc<AsyncMutex<mpsc::Receiver<WorkerEvent>>>,
+  terminate_tx: mpsc::Sender<()>,
+  terminated: Arc<AtomicBool>,
+  isolate_handle: v8::IsolateHandle,
+}
+
+impl WebWorkerHandle {
+  /// Post message to worker as a host.
+  pub fn post_message(&self, buf: Box<[u8]>) -> Result<(), AnyError> {
+    let mut sender = self.sender.clone();
+    sender.try_send(buf)?;
+    Ok(())
+  }
+
+  /// Get the event with lock.
+  /// Return error if more than one listener tries to get event
+  pub async fn get_event(&self) -> Result<Option<WorkerEvent>, AnyError> {
+    let mut receiver = self.receiver.try_lock()?;
+    Ok(receiver.next().await)
+  }
+
+  pub fn terminate(&self) {
+    // This function can be called multiple times by whomever holds
+    // the handle. However only a single "termination" should occur so
+    // we need a guard here.
+    let already_terminated = self.terminated.swap(true, Ordering::Relaxed);
+
+    if !already_terminated {
+      self.isolate_handle.terminate_execution();
+      let mut sender = self.terminate_tx.clone();
+      // This call should be infallible hence the `expect`.
+      // This might change in the future.
+      sender.try_send(()).expect("Failed to terminate");
+    }
+  }
+}
+
+fn create_channels(
+  isolate_handle: v8::IsolateHandle,
+  terminate_tx: mpsc::Sender<()>,
+) -> (WorkerChannelsInternal, WebWorkerHandle) {
+  let (in_tx, in_rx) = mpsc::channel::<Box<[u8]>>(1);
+  let (out_tx, out_rx) = mpsc::channel::<WorkerEvent>(1);
+  let internal_channels = WorkerChannelsInternal {
+    sender: out_tx,
+    receiver: in_rx,
+  };
+  let external_channels = WebWorkerHandle {
+    sender: in_tx,
+    receiver: Arc::new(AsyncMutex::new(out_rx)),
+    terminated: Arc::new(AtomicBool::new(false)),
+    terminate_tx,
+    isolate_handle,
+  };
+  (internal_channels, external_channels)
+}
+
+/// This struct is an implementation of `Worker` Web API
+///
+/// Each `WebWorker` is either a child of `MainWorker` or other
+/// `WebWorker`.
+pub struct WebWorker {
+  inspector: Option<Box<DenoInspector>>,
+  // Following fields are pub because they are accessed
+  // when creating a new WebWorker instance.
+  pub(crate) internal_channels: WorkerChannelsInternal,
+  pub(crate) js_runtime: JsRuntime,
+  pub(crate) name: String,
+  waker: AtomicWaker,
+  event_loop_idle: bool,
+  terminate_rx: mpsc::Receiver<()>,
+  handle: WebWorkerHandle,
+  pub has_deno_namespace: bool,
+}
+
+impl WebWorker {
+  pub fn new(
+    name: String,
+    permissions: Permissions,
+    main_module: ModuleSpecifier,
+    program_state: Arc<ProgramState>,
+    has_deno_namespace: bool,
+  ) -> Self {
+    let module_loader = CliModuleLoader::new_for_worker();
+    let global_state_ = program_state.clone();
+
+    let js_error_create_fn = Box::new(move |core_js_error| {
+      let source_mapped_error =
+        apply_source_map(&core_js_error, global_state_.clone());
+      PrettyJsError::create(source_mapped_error)
+    });
+
+    let mut js_runtime = JsRuntime::new(RuntimeOptions {
+      module_loader: Some(module_loader),
+      startup_snapshot: Some(js::deno_isolate_init()),
+      js_error_create_fn: Some(js_error_create_fn),
+      get_error_class_fn: Some(&crate::errors::get_error_class_name),
+      ..Default::default()
+    });
+
+    let inspector =
+      if let Some(inspector_server) = &program_state.maybe_inspector_server {
+        Some(DenoInspector::new(
+          &mut js_runtime,
+          Some(inspector_server.clone()),
+        ))
+      } else if program_state.flags.coverage || program_state.flags.repl {
+        Some(DenoInspector::new(&mut js_runtime, None))
+      } else {
+        None
+      };
+
+    let (terminate_tx, terminate_rx) = mpsc::channel::<()>(1);
+    let isolate_handle = js_runtime.v8_isolate().thread_safe_handle();
+    let (internal_channels, handle) =
+      create_channels(isolate_handle, terminate_tx);
+
+    let mut worker = Self {
+      inspector,
+      internal_channels,
+      js_runtime,
+      name,
+      waker: AtomicWaker::new(),
+      event_loop_idle: false,
+      terminate_rx,
+      handle,
+      has_deno_namespace,
+    };
+
+    {
+      let handle = worker.thread_safe_handle();
+      let sender = worker.internal_channels.sender.clone();
+      let js_runtime = &mut worker.js_runtime;
+      // All ops registered in this function depend on these
+      {
+        let op_state = js_runtime.op_state();
+        let mut op_state = op_state.borrow_mut();
+        op_state.put::<Metrics>(Default::default());
+        op_state.put::<Arc<ProgramState>>(program_state.clone());
+        op_state.put::<Permissions>(permissions);
+      }
+
+      ops::web_worker::init(js_runtime, sender.clone(), handle);
+      ops::runtime::init(js_runtime, main_module);
+      ops::fetch::init(js_runtime, program_state.flags.ca_file.as_deref());
+      ops::timers::init(js_runtime);
+      ops::worker_host::init(js_runtime, Some(sender));
+      ops::reg_json_sync(js_runtime, "op_close", deno_core::op_close);
+      ops::reg_json_sync(js_runtime, "op_resources", deno_core::op_resources);
+      ops::reg_json_sync(
+        js_runtime,
+        "op_domain_to_ascii",
+        deno_web::op_domain_to_ascii,
+      );
+      ops::errors::init(js_runtime);
+      ops::io::init(js_runtime);
+      ops::websocket::init(js_runtime);
+
+      if has_deno_namespace {
+        ops::fs_events::init(js_runtime);
+        ops::fs::init(js_runtime);
+        ops::net::init(js_runtime);
+        ops::os::init(js_runtime);
+        ops::permissions::init(js_runtime);
+        ops::plugin::init(js_runtime);
+        ops::process::init(js_runtime);
+        ops::crypto::init(js_runtime, program_state.flags.seed);
+        ops::runtime_compiler::init(js_runtime);
+        ops::signal::init(js_runtime);
+        ops::tls::init(js_runtime);
+        ops::tty::init(js_runtime);
+      }
+    }
+
+    worker
+  }
+
+  /// Same as execute2() but the filename defaults to "$CWD/__anonymous__".
+  pub fn execute(&mut self, js_source: &str) -> Result<(), AnyError> {
+    let path = env::current_dir().unwrap().join("__anonymous__");
+    let url = Url::from_file_path(path).unwrap();
+    self.js_runtime.execute(url.as_str(), js_source)
+  }
+
+  /// Loads, instantiates and executes specified JavaScript module.
+  pub async fn execute_module(
+    &mut self,
+    module_specifier: &ModuleSpecifier,
+  ) -> Result<(), AnyError> {
+    let id = self.js_runtime.load_module(module_specifier, None).await?;
+    self.js_runtime.mod_evaluate(id).await
+  }
+
+  /// Returns a way to communicate with the Worker from other threads.
+  pub fn thread_safe_handle(&self) -> WebWorkerHandle {
+    self.handle.clone()
+  }
+
+  pub fn poll_event_loop(
+    &mut self,
+    cx: &mut Context,
+  ) -> Poll<Result<(), AnyError>> {
+    let terminated = self.handle.terminated.load(Ordering::Relaxed);
+
+    if terminated {
+      return Poll::Ready(Ok(()));
+    }
+
+    if !self.event_loop_idle {
+      let poll_result = {
+        // We always poll the inspector if it exists.
+        let _ = self.inspector.as_mut().map(|i| i.poll_unpin(cx));
+        self.waker.register(cx.waker());
+        self.js_runtime.poll_event_loop(cx)
+      };
+      match poll_result {
+        Poll::Ready(r) => {
+          let terminated = self.handle.terminated.load(Ordering::Relaxed);
+          if terminated {
+            return Poll::Ready(Ok(()));
+          }
+
+          if let Err(e) = r {
+            eprintln!(
+              "{}: Uncaught (in worker \"{}\") {}",
+              colors::red_bold("error"),
+              self.name.to_string(),
+              e.to_string().trim_start_matches("Uncaught "),
+            );
+            let mut sender = self.internal_channels.sender.clone();
+            sender
+              .try_send(WorkerEvent::Error(e))
+              .expect("Failed to post message to host");
+          }
+          self.event_loop_idle = true;
+        }
+        Poll::Pending => {}
+      }
+    }
+
+    if let Poll::Ready(r) = self.terminate_rx.poll_next_unpin(cx) {
+      // terminate_rx should never be closed
+      assert!(r.is_some());
+      return Poll::Ready(Ok(()));
+    }
+
+    if let Poll::Ready(r) = self.internal_channels.receiver.poll_next_unpin(cx)
+    {
+      match r {
+        Some(msg) => {
+          let msg = String::from_utf8(msg.to_vec()).unwrap();
+          let script = format!("workerMessageRecvCallback({})", msg);
+
+          if let Err(e) = self.execute(&script) {
+            // If execution was terminated during message callback then
+            // just ignore it
+            if self.handle.terminated.load(Ordering::Relaxed) {
+              return Poll::Ready(Ok(()));
+            }
+
+            // Otherwise forward error to host
+            let mut sender = self.internal_channels.sender.clone();
+            sender
+              .try_send(WorkerEvent::Error(e))
+              .expect("Failed to post message to host");
+          }
+
+          // Let event loop be polled again
+          self.event_loop_idle = false;
+          self.waker.wake();
+        }
+        None => unreachable!(),
+      }
+    }
+
+    Poll::Pending
+  }
+
+  pub async fn run_event_loop(&mut self) -> Result<(), AnyError> {
+    poll_fn(|cx| self.poll_event_loop(cx)).await
+  }
+}
+
+impl Drop for WebWorker {
+  fn drop(&mut self) {
+    // The Isolate object must outlive the Inspector object, but this is
+    // currently not enforced by the type system.
+    self.inspector.take();
+  }
+}
+
+#[cfg(test)]
+mod tests {
+  use super::*;
+  use crate::program_state::ProgramState;
+  use crate::tokio_util;
+  use deno_core::serde_json::json;
+
+  fn create_test_web_worker() -> WebWorker {
+    let main_module =
+      ModuleSpecifier::resolve_url_or_path("./hello.js").unwrap();
+    let program_state = ProgramState::mock(vec!["deno".to_string()], None);
+    let mut worker = WebWorker::new(
+      "TEST".to_string(),
+      Permissions::allow_all(),
+      main_module,
+      program_state,
+      false,
+    );
+    worker
+      .execute("bootstrap.workerRuntime(\"TEST\", false)")
+      .unwrap();
+    worker
+  }
+
+  #[tokio::test]
+  async fn test_worker_messages() {
+    let (handle_sender, handle_receiver) =
+      std::sync::mpsc::sync_channel::<WebWorkerHandle>(1);
+
+    let join_handle = std::thread::spawn(move || {
+      let mut worker = create_test_web_worker();
+      let source = r#"
+          onmessage = function(e) {
+            console.log("msg from main script", e.data);
+            if (e.data == "exit") {
+              return close();
+            } else {
+              console.assert(e.data === "hi");
+            }
+            postMessage([1, 2, 3]);
+            console.log("after postMessage");
+          }
+          "#;
+      worker.execute(source).unwrap();
+      let handle = worker.thread_safe_handle();
+      handle_sender.send(handle).unwrap();
+      let r = tokio_util::run_basic(worker.run_event_loop());
+      assert!(r.is_ok())
+    });
+
+    let mut handle = handle_receiver.recv().unwrap();
+
+    let msg = json!("hi").to_string().into_boxed_str().into_boxed_bytes();
+    let r = handle.post_message(msg.clone());
+    assert!(r.is_ok());
+
+    let maybe_msg = handle.get_event().await.unwrap();
+    assert!(maybe_msg.is_some());
+
+    let r = handle.post_message(msg.clone());
+    assert!(r.is_ok());
+
+    let maybe_msg = handle.get_event().await.unwrap();
+    assert!(maybe_msg.is_some());
+    match maybe_msg {
+      Some(WorkerEvent::Message(buf)) => {
+        assert_eq!(*buf, *b"[1,2,3]");
+      }
+      _ => unreachable!(),
+    }
+
+    let msg = json!("exit")
+      .to_string()
+      .into_boxed_str()
+      .into_boxed_bytes();
+    let r = handle.post_message(msg);
+    assert!(r.is_ok());
+    let event = handle.get_event().await.unwrap();
+    assert!(event.is_none());
+    handle.sender.close_channel();
+    join_handle.join().expect("Failed to join worker thread");
+  }
+
+  #[tokio::test]
+  async fn removed_from_resource_table_on_close() {
+    let (handle_sender, handle_receiver) =
+      std::sync::mpsc::sync_channel::<WebWorkerHandle>(1);
+
+    let join_handle = std::thread::spawn(move || {
+      let mut worker = create_test_web_worker();
+      worker.execute("onmessage = () => { close(); }").unwrap();
+      let handle = worker.thread_safe_handle();
+      handle_sender.send(handle).unwrap();
+      let r = tokio_util::run_basic(worker.run_event_loop());
+      assert!(r.is_ok())
+    });
+
+    let mut handle = handle_receiver.recv().unwrap();
+
+    let msg = json!("hi").to_string().into_boxed_str().into_boxed_bytes();
+    let r = handle.post_message(msg.clone());
+    assert!(r.is_ok());
+    let event = handle.get_event().await.unwrap();
+    assert!(event.is_none());
+    handle.sender.close_channel();
+
+    join_handle.join().expect("Failed to join worker thread");
+  }
+}

cli/worker.rs

@@ -1,6 +1,5 @@
 // Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
 
-use crate::colors;
 use crate::fmt_errors::PrettyJsError;
 use crate::inspector::DenoInspector;
 use crate::inspector::InspectorSession;
@@ -13,109 +12,39 @@ use crate::permissions::Permissions;
 use crate::program_state::ProgramState;
 use crate::source_maps::apply_source_map;
 use deno_core::error::AnyError;
-use deno_core::futures::channel::mpsc;
 use deno_core::futures::future::poll_fn;
 use deno_core::futures::future::FutureExt;
-use deno_core::futures::stream::StreamExt;
-use deno_core::futures::task::AtomicWaker;
 use deno_core::url::Url;
-use deno_core::v8;
 use deno_core::JsRuntime;
 use deno_core::ModuleId;
 use deno_core::ModuleSpecifier;
 use deno_core::RuntimeOptions;
-use deno_core::Snapshot;
 use std::env;
-use std::ops::Deref;
-use std::ops::DerefMut;
-use std::rc::Rc;
-use std::sync::atomic::AtomicBool;
-use std::sync::atomic::Ordering;
 use std::sync::Arc;
 use std::task::Context;
 use std::task::Poll;
-use tokio::sync::Mutex as AsyncMutex;
 
-/// Events that are sent to host from child
+/// This worker is created and used by almost all
-/// worker.
+/// subcommands in Deno executable.
-pub enum WorkerEvent {
-  Message(Box<[u8]>),
-  Error(AnyError),
-  TerminalError(AnyError),
-}
-
-pub struct WorkerChannelsInternal {
-  pub sender: mpsc::Sender<WorkerEvent>,
-  pub receiver: mpsc::Receiver<Box<[u8]>>,
-}
-
-#[derive(Clone)]
-pub struct WorkerHandle {
-  pub sender: mpsc::Sender<Box<[u8]>>,
-  pub receiver: Arc<AsyncMutex<mpsc::Receiver<WorkerEvent>>>,
-}
-
-impl WorkerHandle {
-  /// Post message to worker as a host.
-  pub fn post_message(&self, buf: Box<[u8]>) -> Result<(), AnyError> {
-    let mut sender = self.sender.clone();
-    sender.try_send(buf)?;
-    Ok(())
-  }
-
-  /// Get the event with lock.
-  /// Return error if more than one listener tries to get event
-  pub async fn get_event(&self) -> Result<Option<WorkerEvent>, AnyError> {
-    let mut receiver = self.receiver.try_lock()?;
-    Ok(receiver.next().await)
-  }
-}
-
-fn create_channels() -> (WorkerChannelsInternal, WorkerHandle) {
-  let (in_tx, in_rx) = mpsc::channel::<Box<[u8]>>(1);
-  let (out_tx, out_rx) = mpsc::channel::<WorkerEvent>(1);
-  let internal_channels = WorkerChannelsInternal {
-    sender: out_tx,
-    receiver: in_rx,
-  };
-  let external_channels = WorkerHandle {
-    sender: in_tx,
-    receiver: Arc::new(AsyncMutex::new(out_rx)),
-  };
-  (internal_channels, external_channels)
-}
-
-/// Worker is a CLI wrapper for `deno_core::Isolate`.
 ///
-/// It provides infrastructure to communicate with a worker and
+/// It provides ops available in the `Deno` namespace.
-/// consequently between workers.
 ///
-/// This struct is meant to be used as a base struct for concrete
+/// All `WebWorker`s created during program execution
-/// type of worker that registers set of ops.
+/// are descendants of this worker.
-///
+pub struct MainWorker {
-/// Currently there are two types of workers:
-///  - `MainWorker`
-///  - `WebWorker`
-pub struct Worker {
-  external_channels: WorkerHandle,
   inspector: Option<Box<DenoInspector>>,
-  // Following fields are pub because they are accessed
+  js_runtime: JsRuntime,
-  // when creating a new WebWorker instance.
-  pub(crate) internal_channels: WorkerChannelsInternal,
-  pub(crate) js_runtime: JsRuntime,
-  pub(crate) name: String,
   should_break_on_first_statement: bool,
-  waker: AtomicWaker,
 }
 
-impl Worker {
+impl MainWorker {
   pub fn new(
-    name: String,
+    program_state: &Arc<ProgramState>,
-    startup_snapshot: Snapshot,
+    main_module: ModuleSpecifier,
-    program_state: Arc<ProgramState>,
+    permissions: Permissions,
-    module_loader: Rc<CliModuleLoader>,
-    is_main: bool,
   ) -> Self {
+    let module_loader =
+      CliModuleLoader::new(program_state.maybe_import_map.clone());
     let global_state_ = program_state.clone();
 
     let js_error_create_fn = Box::new(move |core_js_error| {
@@ -126,7 +55,7 @@ impl Worker {
 
     let mut js_runtime = JsRuntime::new(RuntimeOptions {
       module_loader: Some(module_loader),
-      startup_snapshot: Some(startup_snapshot),
+      startup_snapshot: Some(js::deno_isolate_init()),
       js_error_create_fn: Some(js_error_create_fn),
       get_error_class_fn: Some(&crate::errors::get_error_class_name),
       ..Default::default()
@@ -144,126 +73,15 @@ impl Worker {
         None
       };
 
-    let should_break_on_first_statement = inspector.is_some()
+    let should_break_on_first_statement =
-      && is_main
+      inspector.is_some() && program_state.flags.inspect_brk.is_some();
-      && program_state.flags.inspect_brk.is_some();
 
-    let (internal_channels, external_channels) = create_channels();
+    let mut worker = Self {
-
-    Self {
-      external_channels,
       inspector,
-      internal_channels,
       js_runtime,
-      name,
       should_break_on_first_statement,
-      waker: AtomicWaker::new(),
+    };
-    }
-  }
 
-  /// Same as execute2() but the filename defaults to "$CWD/__anonymous__".
-  pub fn execute(&mut self, js_source: &str) -> Result<(), AnyError> {
-    let path = env::current_dir().unwrap().join("__anonymous__");
-    let url = Url::from_file_path(path).unwrap();
-    self.execute2(url.as_str(), js_source)
-  }
-
-  /// Executes the provided JavaScript source code. The js_filename argument is
-  /// provided only for debugging purposes.
-  pub fn execute2(
-    &mut self,
-    js_filename: &str,
-    js_source: &str,
-  ) -> Result<(), AnyError> {
-    self.js_runtime.execute(js_filename, js_source)
-  }
-
-  /// Loads and instantiates specified JavaScript module.
-  pub async fn preload_module(
-    &mut self,
-    module_specifier: &ModuleSpecifier,
-  ) -> Result<ModuleId, AnyError> {
-    self.js_runtime.load_module(module_specifier, None).await
-  }
-
-  /// Loads, instantiates and executes specified JavaScript module.
-  pub async fn execute_module(
-    &mut self,
-    module_specifier: &ModuleSpecifier,
-  ) -> Result<(), AnyError> {
-    let id = self.preload_module(module_specifier).await?;
-    self.wait_for_inspector_session();
-    self.js_runtime.mod_evaluate(id).await
-  }
-
-  /// Returns a way to communicate with the Worker from other threads.
-  pub fn thread_safe_handle(&self) -> WorkerHandle {
-    self.external_channels.clone()
-  }
-
-  fn wait_for_inspector_session(&mut self) {
-    if self.should_break_on_first_statement {
-      self
-        .inspector
-        .as_mut()
-        .unwrap()
-        .wait_for_session_and_break_on_next_statement()
-    }
-  }
-
-  /// Create new inspector session. This function panics if Worker
-  /// was not configured to create inspector.
-  pub fn create_inspector_session(&mut self) -> Box<InspectorSession> {
-    let inspector = self.inspector.as_mut().unwrap();
-
-    InspectorSession::new(&mut **inspector)
-  }
-
-  pub fn poll_event_loop(
-    &mut self,
-    cx: &mut Context,
-  ) -> Poll<Result<(), AnyError>> {
-    // We always poll the inspector if it exists.
-    let _ = self.inspector.as_mut().map(|i| i.poll_unpin(cx));
-    self.waker.register(cx.waker());
-    self.js_runtime.poll_event_loop(cx)
-  }
-
-  pub async fn run_event_loop(&mut self) -> Result<(), AnyError> {
-    poll_fn(|cx| self.poll_event_loop(cx)).await
-  }
-}
-
-impl Drop for Worker {
-  fn drop(&mut self) {
-    // The Isolate object must outlive the Inspector object, but this is
-    // currently not enforced by the type system.
-    self.inspector.take();
-  }
-}
-
-/// This worker is created and used by Deno executable.
-///
-/// It provides ops available in the `Deno` namespace.
-///
-/// All WebWorkers created during program execution are descendants of
-/// this worker.
-pub struct MainWorker(Worker);
-
-impl MainWorker {
-  pub fn new(
-    program_state: &Arc<ProgramState>,
-    main_module: ModuleSpecifier,
-    permissions: Permissions,
-  ) -> Self {
-    let loader = CliModuleLoader::new(program_state.maybe_import_map.clone());
-    let mut worker = Worker::new(
-      "main".to_string(),
-      js::deno_isolate_init(),
-      program_state.clone(),
-      loader,
-      true,
-    );
     let js_runtime = &mut worker.js_runtime;
     {
       // All ops registered in this function depend on these
@@ -320,266 +138,71 @@ impl MainWorker {
     worker
       .execute("bootstrap.mainRuntime()")
       .expect("Failed to execute bootstrap script");
-    Self(worker)
+    worker
+  }
+
+  /// Same as execute2() but the filename defaults to "$CWD/__anonymous__".
+  pub fn execute(&mut self, js_source: &str) -> Result<(), AnyError> {
+    let path = env::current_dir().unwrap().join("__anonymous__");
+    let url = Url::from_file_path(path).unwrap();
+    self.js_runtime.execute(url.as_str(), js_source)
+  }
+
+  /// Loads and instantiates specified JavaScript module.
+  pub async fn preload_module(
+    &mut self,
+    module_specifier: &ModuleSpecifier,
+  ) -> Result<ModuleId, AnyError> {
+    self.js_runtime.load_module(module_specifier, None).await
+  }
+
+  /// Loads, instantiates and executes specified JavaScript module.
+  pub async fn execute_module(
+    &mut self,
+    module_specifier: &ModuleSpecifier,
+  ) -> Result<(), AnyError> {
+    let id = self.preload_module(module_specifier).await?;
+    self.wait_for_inspector_session();
+    self.js_runtime.mod_evaluate(id).await
+  }
+
+  fn wait_for_inspector_session(&mut self) {
+    if self.should_break_on_first_statement {
+      self
+        .inspector
+        .as_mut()
+        .unwrap()
+        .wait_for_session_and_break_on_next_statement()
     }
   }
 
-impl Deref for MainWorker {
+  /// Create new inspector session. This function panics if Worker
-  type Target = Worker;
+  /// was not configured to create inspector.
-  fn deref(&self) -> &Self::Target {
+  pub fn create_inspector_session(&mut self) -> Box<InspectorSession> {
-    &self.0
+    let inspector = self.inspector.as_mut().unwrap();
-  }
-}
 
-impl DerefMut for MainWorker {
+    InspectorSession::new(&mut **inspector)
-  fn deref_mut(&mut self) -> &mut Self::Target {
-    &mut self.0
-  }
-}
-
-/// Wrapper for `WorkerHandle` that adds functionality
-/// for terminating workers.
-///
-/// This struct is used by host as well as worker itself.
-///
-/// Host uses it to communicate with worker and terminate it,
-/// while worker uses it only to finish execution on `self.close()`.
-#[derive(Clone)]
-pub struct WebWorkerHandle {
-  worker_handle: WorkerHandle,
-  terminate_tx: mpsc::Sender<()>,
-  terminated: Arc<AtomicBool>,
-  isolate_handle: v8::IsolateHandle,
-}
-
-impl Deref for WebWorkerHandle {
-  type Target = WorkerHandle;
-  fn deref(&self) -> &Self::Target {
-    &self.worker_handle
-  }
-}
-
-impl DerefMut for WebWorkerHandle {
-  fn deref_mut(&mut self) -> &mut Self::Target {
-    &mut self.worker_handle
-  }
-}
-
-impl WebWorkerHandle {
-  pub fn terminate(&self) {
-    // This function can be called multiple times by whomever holds
-    // the handle. However only a single "termination" should occur so
-    // we need a guard here.
-    let already_terminated = self.terminated.swap(true, Ordering::Relaxed);
-
-    if !already_terminated {
-      self.isolate_handle.terminate_execution();
-      let mut sender = self.terminate_tx.clone();
-      // This call should be infallible hence the `expect`.
-      // This might change in the future.
-      sender.try_send(()).expect("Failed to terminate");
-    }
-  }
-}
-
-/// This worker is implementation of `Worker` Web API
-///
-/// At the moment this type of worker supports only
-/// communication with parent and creating new workers.
-///
-/// Each `WebWorker` is either a child of `MainWorker` or other
-/// `WebWorker`.
-pub struct WebWorker {
-  worker: Worker,
-  event_loop_idle: bool,
-  terminate_rx: mpsc::Receiver<()>,
-  handle: WebWorkerHandle,
-  pub has_deno_namespace: bool,
-}
-
-impl WebWorker {
-  pub fn new(
-    name: String,
-    permissions: Permissions,
-    main_module: ModuleSpecifier,
-    program_state: Arc<ProgramState>,
-    has_deno_namespace: bool,
-  ) -> Self {
-    let loader = CliModuleLoader::new_for_worker();
-    let mut worker = Worker::new(
-      name,
-      js::deno_isolate_init(),
-      program_state.clone(),
-      loader,
-      false,
-    );
-
-    let terminated = Arc::new(AtomicBool::new(false));
-    let isolate_handle = worker.js_runtime.v8_isolate().thread_safe_handle();
-    let (terminate_tx, terminate_rx) = mpsc::channel::<()>(1);
-
-    let handle = WebWorkerHandle {
-      worker_handle: worker.thread_safe_handle(),
-      terminated,
-      isolate_handle,
-      terminate_tx,
-    };
-
-    let mut web_worker = Self {
-      worker,
-      event_loop_idle: false,
-      terminate_rx,
-      handle,
-      has_deno_namespace,
-    };
-
-    {
-      let handle = web_worker.thread_safe_handle();
-      let sender = web_worker.worker.internal_channels.sender.clone();
-      let js_runtime = &mut web_worker.js_runtime;
-      // All ops registered in this function depend on these
-      {
-        let op_state = js_runtime.op_state();
-        let mut op_state = op_state.borrow_mut();
-        op_state.put::<Metrics>(Default::default());
-        op_state.put::<Arc<ProgramState>>(program_state.clone());
-        op_state.put::<Permissions>(permissions);
-      }
-
-      ops::web_worker::init(js_runtime, sender.clone(), handle);
-      ops::runtime::init(js_runtime, main_module);
-      ops::fetch::init(js_runtime, program_state.flags.ca_file.as_deref());
-      ops::timers::init(js_runtime);
-      ops::worker_host::init(js_runtime, Some(sender));
-      ops::reg_json_sync(js_runtime, "op_close", deno_core::op_close);
-      ops::reg_json_sync(js_runtime, "op_resources", deno_core::op_resources);
-      ops::reg_json_sync(
-        js_runtime,
-        "op_domain_to_ascii",
-        deno_web::op_domain_to_ascii,
-      );
-      ops::errors::init(js_runtime);
-      ops::io::init(js_runtime);
-      ops::websocket::init(js_runtime);
-
-      if has_deno_namespace {
-        ops::fs_events::init(js_runtime);
-        ops::fs::init(js_runtime);
-        ops::net::init(js_runtime);
-        ops::os::init(js_runtime);
-        ops::permissions::init(js_runtime);
-        ops::plugin::init(js_runtime);
-        ops::process::init(js_runtime);
-        ops::crypto::init(js_runtime, program_state.flags.seed);
-        ops::runtime_compiler::init(js_runtime);
-        ops::signal::init(js_runtime);
-        ops::tls::init(js_runtime);
-        ops::tty::init(js_runtime);
-      }
-    }
-
-    web_worker
-  }
-}
-
-impl WebWorker {
-  /// Returns a way to communicate with the Worker from other threads.
-  pub fn thread_safe_handle(&self) -> WebWorkerHandle {
-    self.handle.clone()
-  }
-
-  pub async fn run_event_loop(&mut self) -> Result<(), AnyError> {
-    poll_fn(|cx| self.poll_event_loop(cx)).await
   }
 
   pub fn poll_event_loop(
     &mut self,
     cx: &mut Context,
   ) -> Poll<Result<(), AnyError>> {
-    let worker = &mut self.worker;
+    // We always poll the inspector if it exists.
-
+    let _ = self.inspector.as_mut().map(|i| i.poll_unpin(cx));
-    let terminated = self.handle.terminated.load(Ordering::Relaxed);
+    self.js_runtime.poll_event_loop(cx)
-
-    if terminated {
-      return Poll::Ready(Ok(()));
   }
 
-    if !self.event_loop_idle {
+  pub async fn run_event_loop(&mut self) -> Result<(), AnyError> {
-      match worker.poll_event_loop(cx) {
+    poll_fn(|cx| self.poll_event_loop(cx)).await
-        Poll::Ready(r) => {
-          let terminated = self.handle.terminated.load(Ordering::Relaxed);
-          if terminated {
-            return Poll::Ready(Ok(()));
-          }
-
-          if let Err(e) = r {
-            eprintln!(
-              "{}: Uncaught (in worker \"{}\") {}",
-              colors::red_bold("error"),
-              worker.name.to_string(),
-              e.to_string().trim_start_matches("Uncaught "),
-            );
-            let mut sender = worker.internal_channels.sender.clone();
-            sender
-              .try_send(WorkerEvent::Error(e))
-              .expect("Failed to post message to host");
-          }
-          self.event_loop_idle = true;
-        }
-        Poll::Pending => {}
   }
 }
 
-    if let Poll::Ready(r) = self.terminate_rx.poll_next_unpin(cx) {
+impl Drop for MainWorker {
-      // terminate_rx should never be closed
+  fn drop(&mut self) {
-      assert!(r.is_some());
+    // The Isolate object must outlive the Inspector object, but this is
-      return Poll::Ready(Ok(()));
+    // currently not enforced by the type system.
-    }
+    self.inspector.take();
-
-    if let Poll::Ready(r) =
-      worker.internal_channels.receiver.poll_next_unpin(cx)
-    {
-      match r {
-        Some(msg) => {
-          let msg = String::from_utf8(msg.to_vec()).unwrap();
-          let script = format!("workerMessageRecvCallback({})", msg);
-
-          if let Err(e) = worker.execute(&script) {
-            // If execution was terminated during message callback then
-            // just ignore it
-            if self.handle.terminated.load(Ordering::Relaxed) {
-              return Poll::Ready(Ok(()));
-            }
-
-            // Otherwise forward error to host
-            let mut sender = worker.internal_channels.sender.clone();
-            sender
-              .try_send(WorkerEvent::Error(e))
-              .expect("Failed to post message to host");
-          }
-
-          // Let event loop be polled again
-          self.event_loop_idle = false;
-          worker.waker.wake();
-        }
-        None => unreachable!(),
-      }
-    }
-
-    Poll::Pending
-  }
-}
-
-impl Deref for WebWorker {
-  type Target = Worker;
-  fn deref(&self) -> &Self::Target {
-    &self.worker
-  }
-}
-
-impl DerefMut for WebWorker {
-  fn deref_mut(&mut self) -> &mut Self::Target {
-    &mut self.worker
   }
 }
 
@@ -589,9 +212,6 @@ mod tests {
   use crate::flags::DenoSubcommand;
   use crate::flags::Flags;
   use crate::program_state::ProgramState;
-  use crate::tokio_util;
-  use crate::worker::WorkerEvent;
-  use deno_core::serde_json::json;
 
   fn create_test_worker() -> MainWorker {
     let main_module =
@@ -687,105 +307,4 @@ mod tests {
     let result = worker.execute_module(&module_specifier).await;
     assert!(result.is_ok());
   }
-
-  fn create_test_web_worker() -> WebWorker {
-    let main_module =
-      ModuleSpecifier::resolve_url_or_path("./hello.js").unwrap();
-    let program_state = ProgramState::mock(vec!["deno".to_string()], None);
-    let mut worker = WebWorker::new(
-      "TEST".to_string(),
-      Permissions::allow_all(),
-      main_module,
-      program_state,
-      false,
-    );
-    worker
-      .execute("bootstrap.workerRuntime(\"TEST\", false)")
-      .unwrap();
-    worker
-  }
-  #[tokio::test]
-  async fn test_worker_messages() {
-    let (handle_sender, handle_receiver) =
-      std::sync::mpsc::sync_channel::<WebWorkerHandle>(1);
-
-    let join_handle = std::thread::spawn(move || {
-      let mut worker = create_test_web_worker();
-      let source = r#"
-          onmessage = function(e) {
-            console.log("msg from main script", e.data);
-            if (e.data == "exit") {
-              return close();
-            } else {
-              console.assert(e.data === "hi");
-            }
-            postMessage([1, 2, 3]);
-            console.log("after postMessage");
-          }
-          "#;
-      worker.execute(source).unwrap();
-      let handle = worker.thread_safe_handle();
-      handle_sender.send(handle).unwrap();
-      let r = tokio_util::run_basic(worker.run_event_loop());
-      assert!(r.is_ok())
-    });
-
-    let mut handle = handle_receiver.recv().unwrap();
-
-    let msg = json!("hi").to_string().into_boxed_str().into_boxed_bytes();
-    let r = handle.post_message(msg.clone());
-    assert!(r.is_ok());
-
-    let maybe_msg = handle.get_event().await.unwrap();
-    assert!(maybe_msg.is_some());
-
-    let r = handle.post_message(msg.clone());
-    assert!(r.is_ok());
-
-    let maybe_msg = handle.get_event().await.unwrap();
-    assert!(maybe_msg.is_some());
-    match maybe_msg {
-      Some(WorkerEvent::Message(buf)) => {
-        assert_eq!(*buf, *b"[1,2,3]");
-      }
-      _ => unreachable!(),
-    }
-
-    let msg = json!("exit")
-      .to_string()
-      .into_boxed_str()
-      .into_boxed_bytes();
-    let r = handle.post_message(msg);
-    assert!(r.is_ok());
-    let event = handle.get_event().await.unwrap();
-    assert!(event.is_none());
-    handle.sender.close_channel();
-    join_handle.join().expect("Failed to join worker thread");
-  }
-
-  #[tokio::test]
-  async fn removed_from_resource_table_on_close() {
-    let (handle_sender, handle_receiver) =
-      std::sync::mpsc::sync_channel::<WebWorkerHandle>(1);
-
-    let join_handle = std::thread::spawn(move || {
-      let mut worker = create_test_web_worker();
-      worker.execute("onmessage = () => { close(); }").unwrap();
-      let handle = worker.thread_safe_handle();
-      handle_sender.send(handle).unwrap();
-      let r = tokio_util::run_basic(worker.run_event_loop());
-      assert!(r.is_ok())
-    });
-
-    let mut handle = handle_receiver.recv().unwrap();
-
-    let msg = json!("hi").to_string().into_boxed_str().into_boxed_bytes();
-    let r = handle.post_message(msg.clone());
-    assert!(r.is_ok());
-    let event = handle.get_event().await.unwrap();
-    assert!(event.is_none());
-    handle.sender.close_channel();
-
-    join_handle.join().expect("Failed to join worker thread");
-  }
 }