Organize dispatch a bit (#2796)

Just some clean up reorganization around flatbuffer/minimal dispatch
code. This is prep for adding a JSON dispatcher.

1 files changed, 48 insertions, 0 deletions

diff --git a/cli/ops/utils.rs b/cli/ops/utils.rs
new file mode 100644
index 000000000..a9b0b442c
--- /dev/null
+++ b/cli/ops/utils.rs
@@ -0,0 +1,48 @@
+use crate::tokio_util;
+use deno::Buf;
+use deno::ErrBox;
+use deno::Op;
+use deno::OpResult;
+use futures::Poll;
+
+pub type CliOpResult = OpResult<ErrBox>;
+
+#[inline]
+pub fn ok_buf(buf: Buf) -> CliOpResult {
+  Ok(Op::Sync(buf))
+}
+
+#[inline]
+pub fn empty_buf() -> Buf {
+  Box::new([])
+}
+
+// This is just type conversion. Implement From trait?
+// See https://github.com/tokio-rs/tokio/blob/ffd73a64e7ec497622b7f939e38017afe7124dc4/tokio-fs/src/lib.rs#L76-L85
+fn convert_blocking<F>(f: F) -> Poll<Buf, ErrBox>
+where
+  F: FnOnce() -> Result<Buf, ErrBox>,
+{
+  use futures::Async::*;
+  match tokio_threadpool::blocking(f) {
+    Ok(Ready(Ok(v))) => Ok(v.into()),
+    Ok(Ready(Err(err))) => Err(err),
+    Ok(NotReady) => Ok(NotReady),
+    Err(err) => panic!("blocking error {}", err),
+  }
+}
+
+pub fn blocking<F>(is_sync: bool, f: F) -> CliOpResult
+where
+  F: 'static + Send + FnOnce() -> Result<Buf, ErrBox>,
+{
+  if is_sync {
+    let result_buf = f()?;
+    Ok(Op::Sync(result_buf))
+  } else {
+    Ok(Op::Async(Box::new(futures::sync::oneshot::spawn(
+      tokio_util::poll_fn(move || convert_blocking(f)),
+      &tokio_executor::DefaultExecutor::current(),
+    ))))
+  }
+}