refactor(rt): replace spawn and run with wrapped functions

src/rt.rs

@@ -8,4 +8,48 @@
 
 pub use futures::{Future, Stream};
 pub use futures::future::{lazy, poll_fn};
-pub use tokio::{run, spawn};
+use tokio;
+
+use self::inner::Spawn;
+
+/// Spawns a future on the default executor.
+///
+/// # Panics
+///
+/// This function will panic if the default executor is not set.
+///
+/// # Note
+///
+/// The `Spawn` return type is not currently meant for anything other than
+/// to reserve adding new trait implementations to it later. It can be
+/// ignored for now.
+pub fn spawn<F>(f: F) -> Spawn
+where
+    F: Future<Item=(), Error=()> + Send + 'static,
+{
+    tokio::spawn(f);
+    Spawn {
+        _inner: (),
+    }
+}
+
+/// Start the Tokio runtime using the supplied future to bootstrap execution.
+///
+/// # Example
+///
+/// See the [server documentation](::server) for an example of its usage.
+pub fn run<F>(f: F)
+where
+    F: Future<Item=(), Error=()> + Send + 'static
+{
+    tokio::run(f);
+}
+
+// Make the `Spawn` type an unnameable, so we can add
+// methods or trait impls to it later without a breaking change.
+mod inner {
+    #[allow(missing_debug_implementations)]
+    pub struct Spawn {
+        pub(super) _inner: (),
+    }
+}