Remove dead futures2 code. (#538)

The futures 0.2 crate is not intended for widespread usage. Also, the
futures team is exploring the compat shim route.

If futures 0.3 support is added to Tokio 0.1, then a different
integration route will be explored, making the current code unhelpful.

src/executor/mod.rs

@@ -61,9 +61,6 @@ pub use tokio_executor::{Executor, DefaultExecutor, SpawnError};
 use futures::{Future, IntoFuture};
 use futures::future::{self, FutureResult};
 
-#[cfg(feature = "unstable-futures")]
-use futures2;
-
 /// Return value from the `spawn` function.
 ///
 /// Currently this value doesn't actually provide any functionality. However, it
@@ -133,15 +130,6 @@ where F: Future<Item = (), Error = ()> + 'static + Send
     Spawn(())
 }
 
-/// Like `spawn`, but compatible with futures 0.2
-#[cfg(feature = "unstable-futures")]
-pub fn spawn2<F>(f: F) -> Spawn
-    where F: futures2::Future<Item = (), Error = futures2::Never> + 'static + Send
-{
-    ::tokio_executor::spawn2(f);
-    Spawn(())
-}
-
 impl IntoFuture for Spawn {
     type Future = FutureResult<(), ()>;
     type Item = ();
@@ -151,14 +139,3 @@ impl IntoFuture for Spawn {
         future::ok(())
     }
 }
-
-#[cfg(feature = "unstable-futures")]
-impl futures2::IntoFuture for Spawn {
-    type Future = futures2::future::FutureResult<(), ()>;
-    type Item = ();
-    type Error = ();
-
-    fn into_future(self) -> Self::Future {
-        futures2::future::ok(())
-    }
-}

src/lib.rs

@@ -80,9 +80,6 @@ extern crate tokio_timer;
 extern crate tokio_tcp;
 extern crate tokio_udp;
 
-#[cfg(feature = "unstable-futures")]
-extern crate futures2;
-
 pub mod clock;
 pub mod executor;
 pub mod fs;
@@ -93,9 +90,6 @@ pub mod timer;
 pub mod util;
 
 pub use executor::spawn;
-#[cfg(feature = "unstable-futures")]
-pub use executor::spawn2;
-
 pub use runtime::run;
 
 pub mod io {

src/runtime/mod.rs

@@ -129,8 +129,6 @@ use tokio_threadpool as threadpool;
 
 use futures;
 use futures::future::Future;
-#[cfg(feature = "unstable-futures")]
-use futures2;
 
 /// Handle to the Tokio runtime.
 ///
@@ -215,18 +213,6 @@ where F: Future<Item = (), Error = ()> + Send + 'static,
     runtime.shutdown_on_idle().wait().unwrap();
 }
 
-/// Start the Tokio runtime using the supplied future to bootstrap execution.
-///
-/// Identical to `run` but works with futures 0.2-style futures.
-#[cfg(feature = "unstable-futures")]
-pub fn run2<F>(future: F)
-    where F: futures2::Future<Item = (), Error = futures2::Never> + Send + 'static,
-{
-    let mut runtime = Runtime::new().unwrap();
-    runtime.spawn2(future);
-    runtime.shutdown_on_idle().wait().unwrap();
-}
-
 impl Runtime {
     /// Create a new runtime instance with default configuration values.
     ///
@@ -353,19 +339,6 @@ impl Runtime {
         self
     }
 
-    /// Spawn a futures 0.2-style future onto the Tokio runtime.
-    ///
-    /// Otherwise identical to `spawn`
-    #[cfg(feature = "unstable-futures")]
-    pub fn spawn2<F>(&mut self, future: F) -> &mut Self
-        where F: futures2::Future<Item = (), Error = futures2::Never> + Send + 'static,
-    {
-        futures2::executor::Executor::spawn(
-            self.inner_mut().pool.sender_mut(), Box::new(future)
-        ).unwrap();
-        self
-    }
-
     /// Run a future to completion on the Tokio runtime.
     ///
     /// This runs the given future on the runtime, blocking until it is

src/runtime/task_executor.rs

@@ -2,8 +2,6 @@
 use tokio_threadpool::Sender;
 
 use futures::future::{self, Future};
-#[cfg(feature = "unstable-futures")]
-use futures2;
 
 /// Executes futures on the runtime
 ///
@@ -74,25 +72,4 @@ impl ::executor::Executor for TaskExecutor {
     {
         self.inner.spawn(future)
     }
-
-    #[cfg(feature = "unstable-futures")]
-    fn spawn2(&mut self, future: Box<futures2::Future<Item = (), Error = futures2::Never> + Send>)
-        -> Result<(), futures2::executor::SpawnError>
-    {
-        self.inner.spawn2(future)
-    }
-}
-
-#[cfg(feature = "unstable-futures")]
-type Task2 = Box<futures2::Future<Item = (), Error = futures2::Never> + Send>;
-
-#[cfg(feature = "unstable-futures")]
-impl futures2::executor::Executor for TaskExecutor {
-    fn spawn(&mut self, f: Task2) -> Result<(), futures2::executor::SpawnError> {
-        futures2::executor::Executor::spawn(&mut self.inner, f)
-    }
-
-    fn status(&self) -> Result<(), futures2::executor::SpawnError> {
-        futures2::executor::Executor::status(&self.inner)
-    }
 }