perf: eager poll async ops in Isolate (#3046)

cli/js/dispatch_json.ts

@@ -75,11 +75,17 @@ export async function sendAsync(
   const promiseId = nextPromiseId();
   args = Object.assign(args, { promiseId });
   const promise = util.createResolvable<Ok>();
-  promiseTable.set(promiseId, promise);
 
   const argsUi8 = encode(args);
-  const resUi8 = core.dispatch(opId, argsUi8, zeroCopy);
-  util.assert(resUi8 == null);
+  const buf = core.dispatch(opId, argsUi8, zeroCopy);
+  if (buf) {
+    // Sync result.
+    const res = decode(buf);
+    promise.resolve(res);
+  } else {
+    // Async result.
+    promiseTable.set(promiseId, promise);
+  }
 
   const res = await promise;
   return unwrapResponse(res);

cli/js/dispatch_minimal.ts

@@ -61,8 +61,20 @@ export function sendAsyncMinimal(
   scratch32[1] = arg;
   scratch32[2] = 0; // result
   const promise = util.createResolvable<number>();
+  const buf = core.dispatch(opId, scratchBytes, zeroCopy);
+  if (buf) {
+    const buf32 = new Int32Array(
+      buf.buffer,
+      buf.byteOffset,
+      buf.byteLength / 4
+    );
+    const record = recordFromBufMinimal(opId, buf32);
+    // Sync result.
+    promise.resolve(record.result);
+  } else {
+    // Async result.
     promiseTableMin.set(promiseId, promise);
-  core.dispatch(opId, scratchBytes, zeroCopy);
+  }
   return promise;
 }
 

cli/lib.rs

@@ -298,13 +298,17 @@ fn eval_command(flags: DenoFlags, argv: Vec<String>) {
 }
 
 fn bundle_command(flags: DenoFlags, argv: Vec<String>) {
-  let (mut _worker, state) = create_worker_and_state(flags, argv);
+  let (worker, state) = create_worker_and_state(flags, argv);
 
   let main_module = state.main_module().unwrap();
   assert!(state.argv.len() >= 3);
   let out_file = state.argv[2].clone();
   debug!(">>>>> bundle_async START");
-  let bundle_future = state
+  // NOTE: we need to poll `worker` otherwise TS compiler worker won't run properly
+  let main_future = lazy(move || {
+    worker.then(move |result| {
+      js_check(result);
+      state
         .ts_compiler
         .bundle_async(state.clone(), main_module.to_string(), out_file)
         .map_err(|err| {
@@ -315,8 +319,10 @@ fn bundle_command(flags: DenoFlags, argv: Vec<String>) {
         .and_then(move |_| {
           debug!(">>>>> bundle_async END");
           Ok(())
+        })
+    })
   });
-  tokio_util::run(bundle_future);
+  tokio_util::run(main_future);
 }
 
 fn run_repl(flags: DenoFlags, argv: Vec<String>) {

cli/tokio_util.rs

@@ -7,6 +7,7 @@ use futures::Poll;
 use std::io;
 use std::mem;
 use std::net::SocketAddr;
+use std::ops::FnOnce;
 use tokio;
 use tokio::net::TcpStream;
 use tokio::runtime;
@@ -78,6 +79,7 @@ where
 
 #[derive(Debug)]
 enum AcceptState {
+  Eager(Resource),
   Pending(Resource),
   Empty,
 }
@@ -85,7 +87,7 @@ enum AcceptState {
 /// Simply accepts a connection.
 pub fn accept(r: Resource) -> Accept {
   Accept {
-    state: AcceptState::Pending(r),
+    state: AcceptState::Eager(r),
   }
 }
 
@@ -107,6 +109,16 @@ impl Future for Accept {
       // in TcpListener resource.
       // In this way, when the listener is closed, the task can be
       // notified to error out (instead of stuck forever).
+      AcceptState::Eager(ref mut r) => match r.poll_accept() {
+        Ok(futures::prelude::Async::Ready(t)) => t,
+        Ok(futures::prelude::Async::NotReady) => {
+          self.state = AcceptState::Pending(r.to_owned());
+          return Ok(futures::prelude::Async::NotReady);
+        }
+        Err(e) => {
+          return Err(e);
+        }
+      },
       AcceptState::Pending(ref mut r) => match r.poll_accept() {
         Ok(futures::prelude::Async::Ready(t)) => {
           r.untrack_task();
@@ -126,8 +138,8 @@ impl Future for Accept {
     };
 
     match mem::replace(&mut self.state, AcceptState::Empty) {
-      AcceptState::Pending(_) => Ok((stream, addr).into()),
       AcceptState::Empty => panic!("invalid internal state"),
+      _ => Ok((stream, addr).into()),
     }
   }
 }
@@ -166,3 +178,16 @@ where
 {
   f.map_err(|err| panic!("Future got unexpected error: {:?}", err))
 }
+
+#[cfg(test)]
+pub fn run_in_task<F>(f: F)
+where
+  F: FnOnce() + Send + 'static,
+{
+  let fut = futures::future::lazy(move || {
+    f();
+    futures::future::ok(())
+  });
+
+  run(fut)
+}

cli/worker.rs

@@ -263,7 +263,7 @@ mod tests {
 
   #[test]
   fn test_worker_messages() {
-    tokio_util::init(|| {
+    tokio_util::run_in_task(|| {
       let mut worker = create_test_worker();
       let source = r#"
         onmessage = function(e) {
@@ -314,7 +314,7 @@ mod tests {
 
   #[test]
   fn removed_from_resource_table_on_close() {
-    tokio_util::init(|| {
+    tokio_util::run_in_task(|| {
       let mut worker = create_test_worker();
       worker
         .execute("onmessage = () => { delete window.onmessage; }")
@@ -349,7 +349,7 @@ mod tests {
 
   #[test]
   fn execute_mod_resolve_error() {
-    tokio_util::init(|| {
+    tokio_util::run_in_task(|| {
       // "foo" is not a valid module specifier so this should return an error.
       let mut worker = create_test_worker();
       let module_specifier =
@@ -361,7 +361,7 @@ mod tests {
 
   #[test]
   fn execute_mod_002_hello() {
-    tokio_util::init(|| {
+    tokio_util::run_in_task(|| {
       // This assumes cwd is project root (an assumption made throughout the
       // tests).
       let mut worker = create_test_worker();

core/examples/http_bench.js

@@ -43,11 +43,25 @@ function send(promiseId, opId, arg, zeroCopy = null) {
 function sendAsync(opId, arg, zeroCopy = null) {
   const promiseId = nextPromiseId++;
   const p = createResolvable();
+  const buf = send(promiseId, opId, arg, zeroCopy);
+  if (buf) {
+    const record = recordFromBuf(buf);
+    // Sync result.
+    p.resolve(record.result);
+  } else {
+    // Async result.
     promiseMap.set(promiseId, p);
-  send(promiseId, opId, arg, zeroCopy);
+  }
   return p;
 }
 
+/** Returns i32 number */
+function sendSync(opId, arg) {
+  const buf = send(0, opId, arg);
+  const record = recordFromBuf(buf);
+  return record.result;
+}
+
 function recordFromBuf(buf) {
   assert(buf.byteLength === 3 * 4);
   const buf32 = new Int32Array(buf.buffer, buf.byteOffset, buf.byteLength / 4);
@@ -58,13 +72,6 @@ function recordFromBuf(buf) {
   };
 }
 
-/** Returns i32 number */
-function sendSync(opId, arg) {
-  const buf = send(0, opId, arg);
-  const record = recordFromBuf(buf);
-  return record.result;
-}
-
 function handleAsyncMsgFromRust(opId, buf) {
   const record = recordFromBuf(buf);
   const { promiseId, result } = record;

core/isolate.rs

@@ -315,6 +315,21 @@ impl Isolate {
       PinnedBuf::new(zero_copy_buf),
     );
 
+    let op = match op {
+      Op::Async(mut fut) => {
+        // Tries to greedily poll async ops once. Often they are immediately ready, in
+        // which case they can be turned into a sync op before we return to V8. This
+        // can save a boundary crossing.
+        #[allow(clippy::match_wild_err_arm)]
+        match fut.poll() {
+          Err(_) => panic!("unexpected op error"),
+          Ok(Ready(buf)) => Op::Sync(buf),
+          Ok(NotReady) => Op::Async(fut),
+        }
+      }
+      Op::Sync(buf) => Op::Sync(buf),
+    };
+
     debug_assert_eq!(isolate.shared.size(), 0);
     match op {
       Op::Sync(buf) => {
@@ -748,8 +763,34 @@ pub mod tests {
     )
   }
 
+  struct DelayedFuture {
+    counter: u32,
+    buf: Box<[u8]>,
+  }
+
+  impl DelayedFuture {
+    pub fn new(buf: Box<[u8]>) -> Self {
+      DelayedFuture { counter: 0, buf }
+    }
+  }
+
+  impl Future for DelayedFuture {
+    type Item = Box<[u8]>;
+    type Error = ();
+
+    fn poll(&mut self) -> Poll<Self::Item, Self::Error> {
+      if self.counter > 0 {
+        return Ok(Async::Ready(self.buf.clone()));
+      }
+
+      self.counter += 1;
+      Ok(Async::NotReady)
+    }
+  }
+
   pub enum Mode {
     AsyncImmediate,
+    AsyncDelayed,
     OverflowReqSync,
     OverflowResSync,
     OverflowReqAsync,
@@ -772,6 +813,12 @@ pub mod tests {
             let buf = vec![43u8, 0, 0, 0].into_boxed_slice();
             Op::Async(Box::new(futures::future::ok(buf)))
           }
+          Mode::AsyncDelayed => {
+            assert_eq!(control.len(), 1);
+            assert_eq!(control[0], 42);
+            let buf = vec![43u8, 0, 0, 0].into_boxed_slice();
+            Op::Async(Box::new(DelayedFuture::new(buf)))
+          }
           Mode::OverflowReqSync => {
             assert_eq!(control.len(), 100 * 1024 * 1024);
             let buf = vec![43u8, 0, 0, 0].into_boxed_slice();
@@ -789,7 +836,7 @@ pub mod tests {
           Mode::OverflowReqAsync => {
             assert_eq!(control.len(), 100 * 1024 * 1024);
             let buf = vec![43u8, 0, 0, 0].into_boxed_slice();
-            Op::Async(Box::new(futures::future::ok(buf)))
+            Op::Async(Box::new(DelayedFuture::new(buf)))
           }
           Mode::OverflowResAsync => {
             assert_eq!(control.len(), 1);
@@ -798,7 +845,7 @@ pub mod tests {
             vec.resize(100 * 1024 * 1024, 0);
             vec[0] = 4;
             let buf = vec.into_boxed_slice();
-            Op::Async(Box::new(futures::future::ok(buf)))
+            Op::Async(Box::new(DelayedFuture::new(buf)))
           }
         }
       };
@@ -889,6 +936,50 @@ pub mod tests {
     run_in_task(|| {
       let (mut isolate, dispatch_count) = setup(Mode::AsyncImmediate);
 
+      js_check(isolate.execute(
+        "setup2.js",
+        r#"
+         let nrecv = 0;
+         Deno.core.setAsyncHandler((opId, buf) => {
+           nrecv++;
+         });
+         "#,
+      ));
+      assert_eq!(dispatch_count.load(Ordering::Relaxed), 0);
+      js_check(isolate.execute(
+        "check1.js",
+        r#"
+         assert(nrecv == 0);
+         let control = new Uint8Array([42]);
+         const res1 = Deno.core.send(1, control);
+         assert(res1);
+         assert(nrecv == 0);
+         "#,
+      ));
+      assert_eq!(dispatch_count.load(Ordering::Relaxed), 1);
+      assert_eq!(dispatch_count.load(Ordering::Relaxed), 1);
+      js_check(isolate.execute(
+        "check2.js",
+        r#"
+         assert(nrecv == 0);
+         Deno.core.send(1, control);
+         assert(nrecv == 0);
+         "#,
+      ));
+      assert_eq!(dispatch_count.load(Ordering::Relaxed), 2);
+      assert_eq!(dispatch_count.load(Ordering::Relaxed), 2);
+      assert_eq!(Async::Ready(()), isolate.poll().unwrap());
+      js_check(isolate.execute("check3.js", "assert(nrecv == 0)"));
+      // We are idle, so the next poll should be the last.
+      assert_eq!(Async::Ready(()), isolate.poll().unwrap());
+    });
+  }
+
+  #[test]
+  fn test_poll_async_delayed_ops() {
+    run_in_task(|| {
+      let (mut isolate, dispatch_count) = setup(Mode::AsyncDelayed);
+
       js_check(isolate.execute(
         "setup2.js",
         r#"

core/libdeno/api.cc

@@ -165,7 +165,7 @@ void deno_respond(Deno* d_, void* user_data, deno_op_id op_id, deno_buf buf) {
   if (d->current_args_ != nullptr) {
     // Synchronous response.
     // Note op_id is not passed back in the case of synchronous response.
-    if (buf.data_ptr != nullptr) {
+    if (buf.data_ptr != nullptr && buf.data_len > 0) {
       auto ab = deno::ImportBuf(d, buf);
       d->current_args_->GetReturnValue().Set(ab);
     }