1 files changed, 110 insertions, 0 deletions
diff --git a/cli/ops/dispatch_minimal.rs b/cli/ops/dispatch_minimal.rs
new file mode 100644
index 000000000..be2cafea4
--- /dev/null
+++ b/cli/ops/dispatch_minimal.rs
@@ -0,0 +1,110 @@
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+// Do not add flatbuffer dependencies to this module.
+//! Connects to js/dispatch_minimal.ts sendAsyncMinimal This acts as a faster
+//! alternative to flatbuffers using a very simple list of int32s to lay out
+//! messages. The first i32 is used to determine if a message a flatbuffer
+//! message or a "minimal" message.
+use crate::state::ThreadSafeState;
+use deno::Buf;
+use deno::CoreOp;
+use deno::ErrBox;
+use deno::Op;
+use deno::PinnedBuf;
+use futures::Future;
+
+#[derive(Copy, Clone, Debug, PartialEq)]
+// This corresponds to RecordMinimal on the TS side.
+pub struct Record {
+  pub promise_id: i32,
+  pub arg: i32,
+  pub result: i32,
+}
+
+impl Into<Buf> for Record {
+  fn into(self) -> Buf {
+    let vec = vec![self.promise_id, self.arg, self.result];
+    let buf32 = vec.into_boxed_slice();
+    let ptr = Box::into_raw(buf32) as *mut [u8; 3 * 4];
+    unsafe { Box::from_raw(ptr) }
+  }
+}
+
+pub fn parse_min_record(bytes: &[u8]) -> Option<Record> {
+  if bytes.len() % std::mem::size_of::<i32>() != 0 {
+    return None;
+  }
+  let p = bytes.as_ptr();
+  #[allow(clippy::cast_ptr_alignment)]
+  let p32 = p as *const i32;
+  let s = unsafe { std::slice::from_raw_parts(p32, bytes.len() / 4) };
+
+  if s.len() != 3 {
+    return None;
+  }
+  let ptr = s.as_ptr();
+  let ints = unsafe { std::slice::from_raw_parts(ptr, 3) };
+  Some(Record {
+    promise_id: ints[0],
+    arg: ints[1],
+    result: ints[2],
+  })
+}
+
+#[test]
+fn test_parse_min_record() {
+  let buf = vec![1, 0, 0, 0, 3, 0, 0, 0, 4, 0, 0, 0];
+  assert_eq!(
+    parse_min_record(&buf),
+    Some(Record {
+      promise_id: 1,
+      arg: 3,
+      result: 4,
+    })
+  );
+
+  let buf = vec![];
+  assert_eq!(parse_min_record(&buf), None);
+
+  let buf = vec![5];
+  assert_eq!(parse_min_record(&buf), None);
+}
+
+pub type MinimalOp = dyn Future<Item = i32, Error = ErrBox> + Send;
+pub type Dispatcher = fn(i32, Option<PinnedBuf>) -> Box<MinimalOp>;
+
+pub fn dispatch(
+  d: Dispatcher,
+  state: &ThreadSafeState,
+  control: &[u8],
+  zero_copy: Option<PinnedBuf>,
+) -> CoreOp {
+  let mut record = parse_min_record(control).unwrap();
+  let is_sync = record.promise_id == 0;
+
+  let state = state.clone();
+
+  let rid = record.arg;
+  let min_op = d(rid, zero_copy);
+
+  let fut = Box::new(min_op.then(move |result| -> Result<Buf, ()> {
+    match result {
+      Ok(r) => {
+        record.result = r;
+      }
+      Err(err) => {
+        // TODO(ry) The dispatch_minimal doesn't properly pipe errors back to
+        // the caller.
+        debug!("swallowed err {}", err);
+        record.result = -1;
+      }
+    }
+    let buf: Buf = record.into();
+    state.metrics_op_completed(buf.len());
+    Ok(buf)
+  }));
+  if is_sync {
+    Op::Sync(fut.wait().unwrap())
+  } else {
+    Op::Async(fut)
+  }
+}