deno/src/workers.rs

// Copyright 2018 the Deno authors. All rights reserved. MIT license.
use isolate::Buf;
use isolate::Isolate;
use isolate::IsolateState;
use isolate::WorkerChannels;
use js_errors::JSError;
use ops;
use resources;
use snapshot;
use tokio_util;

use futures::sync::mpsc;
use futures::sync::oneshot;
use futures::Future;
use std::sync::Arc;
use std::thread;

/// Rust interface for WebWorkers.
pub struct Worker {
  isolate: Isolate,
}

impl Worker {
  pub fn new(parent_state: &Arc<IsolateState>) -> (Self, WorkerChannels) {
    let (worker_in_tx, worker_in_rx) = mpsc::channel::<Buf>(1);
    let (worker_out_tx, worker_out_rx) = mpsc::channel::<Buf>(1);

    let internal_channels = (worker_out_tx, worker_in_rx);
    let external_channels = (worker_in_tx, worker_out_rx);

    let state = Arc::new(IsolateState::new(
      parent_state.flags.clone(),
      parent_state.argv.clone(),
      Some(internal_channels),
    ));

    let snapshot = snapshot::deno_snapshot();
    let isolate = Isolate::new(snapshot, state, ops::dispatch);

    let worker = Worker { isolate };
    (worker, external_channels)
  }

  pub fn execute(&self, js_source: &str) -> Result<(), JSError> {
    self.isolate.execute(js_source)
  }

  pub fn event_loop(&self) -> Result<(), JSError> {
    self.isolate.event_loop()
  }
}

pub fn spawn(
  state: Arc<IsolateState>,
  js_source: String,
) -> resources::Resource {
  // TODO This function should return a Future, so that the caller can retrieve
  // the JSError if one is thrown. Currently it just prints to stderr and calls
  // exit(1).
  // let (js_error_tx, js_error_rx) = oneshot::channel::<JSError>();
  let (p, c) = oneshot::channel::<resources::Resource>();
  let builder = thread::Builder::new().name("worker".to_string());
  let _tid = builder
    .spawn(move || {
      let (worker, external_channels) = Worker::new(&state);

      let resource = resources::add_worker(external_channels);
      p.send(resource.clone()).unwrap();

      tokio_util::init(|| {
        (|| -> Result<(), JSError> {
          worker.execute("denoMain()")?;
          worker.execute("workerMain()")?;
          worker.execute(&js_source)?;
          worker.event_loop()?;
          Ok(())
        })().or_else(|err: JSError| -> Result<(), JSError> {
          eprintln!("{}", err.to_string());
          std::process::exit(1)
        }).unwrap();
      });

      resource.close();
    }).unwrap();

  let resource = c.wait().unwrap();

  resource
}

#[cfg(test)]
mod tests {
  use super::*;

  #[test]
  fn test_spawn() {
    let resource = spawn(
      IsolateState::mock(),
      r#"
      onmessage = function(e) {
        let s = new TextDecoder().decode(e.data);;
        console.log("msg from main script", s);
        if (s == "exit") {
          close();
          return;
        } else {
          console.assert(s === "hi");
        }
        postMessage(new Uint8Array([1, 2, 3]));
        console.log("after postMessage");
      }
    "#.into(),
    );
    let msg = String::from("hi").into_boxed_str().into_boxed_bytes();

    let r = resources::worker_post_message(resource.rid, msg).wait();
    assert!(r.is_ok());

    let maybe_msg =
      resources::worker_recv_message(resource.rid).wait().unwrap();
    assert!(maybe_msg.is_some());
    assert_eq!(*maybe_msg.unwrap(), [1, 2, 3]);

    let msg = String::from("exit").into_boxed_str().into_boxed_bytes();
    let r = resources::worker_post_message(resource.rid, msg).wait();
    assert!(r.is_ok());
  }

  #[test]
  fn removed_from_resource_table_on_close() {
    let resource =
      spawn(IsolateState::mock(), "onmessage = () => close();".into());

    assert_eq!(
      resources::get_type(resource.rid),
      Some("worker".to_string())
    );

    let msg = String::from("hi").into_boxed_str().into_boxed_bytes();
    let r = resources::worker_post_message(resource.rid, msg).wait();
    assert!(r.is_ok());
    println!("rid {:?}", resource.rid);

    // TODO Need a way to get a future for when a resource closes.
    // For now, just sleep for a bit.
    // resource.close();
    thread::sleep(std::time::Duration::from_millis(1000));
    assert_eq!(resources::get_type(resource.rid), None);
  }
}