Remove executor from reactor.

In accordance with tokio-rs/tokio-rfcs#3, the executor functionality of
Tokio is being removed and will be relocated into futures-rs as a
"current thread" executor.

This PR removes task execution from the code base. As a temporary
mesure, all examples and tests are switched to using CpuPool.

Depends on #19.

examples/connect.rs

@@ -15,6 +15,7 @@
 //! stdin/stdout to a server" to get up and running.
 
 extern crate futures;
+extern crate futures_cpupool;
 extern crate tokio;
 extern crate tokio_io;
 extern crate bytes;
@@ -26,6 +27,7 @@ use std::thread;
 
 use futures::sync::mpsc;
 use futures::{Sink, Future, Stream};
+use futures_cpupool::CpuPool;
 use tokio::reactor::Core;
 
 fn main() {
@@ -49,6 +51,8 @@ fn main() {
     let mut core = Core::new().unwrap();
     let handle = core.handle();
 
+    let pool = CpuPool::new(1);
+
     // Right now Tokio doesn't support a handle to stdin running on the event
     // loop, so we farm out that work to a separate thread. This thread will
     // read data (with blocking I/O) from stdin and then send it to the event
@@ -61,9 +65,9 @@ fn main() {
     // our UDP connection to get a stream of bytes we're going to emit to
     // stdout.
     let stdout = if tcp {
-        tcp::connect(&addr, &handle, Box::new(stdin_rx))
+        tcp::connect(&addr, &handle, &pool, Box::new(stdin_rx))
     } else {
-        udp::connect(&addr, &handle, Box::new(stdin_rx))
+        udp::connect(&addr, &handle, &pool, Box::new(stdin_rx))
     };
 
     // And now with our stream of bytes to write to stdout, we execute that in
@@ -83,6 +87,8 @@ mod tcp {
 
     use bytes::{BufMut, BytesMut};
     use futures::{Future, Stream};
+    use futures::future::Executor;
+    use futures_cpupool::CpuPool;
     use tokio::net::TcpStream;
     use tokio::reactor::Handle;
     use tokio_io::AsyncRead;
@@ -90,11 +96,12 @@ mod tcp {
 
     pub fn connect(addr: &SocketAddr,
                    handle: &Handle,
-                   stdin: Box<Stream<Item = Vec<u8>, Error = io::Error>>)
+                   pool: &CpuPool,
+                   stdin: Box<Stream<Item = Vec<u8>, Error = io::Error> + Send>)
         -> Box<Stream<Item = BytesMut, Error = io::Error>>
     {
         let tcp = TcpStream::connect(addr, handle);
-        let handle = handle.clone();
+        let pool = pool.clone();
 
         // After the TCP connection has been established, we set up our client
         // to start forwarding data.
@@ -113,12 +120,12 @@ mod tcp {
         // with us reading data from the stream.
         Box::new(tcp.map(move |stream| {
             let (sink, stream) = stream.framed(Bytes).split();
-            handle.spawn(stdin.forward(sink).then(|result| {
+            pool.execute(stdin.forward(sink).then(|result| {
                 if let Err(e) = result {
                     panic!("failed to write to socket: {}", e)
                 }
                 Ok(())
-            }));
+            })).unwrap();
             stream
         }).flatten_stream())
     }
@@ -167,12 +174,15 @@ mod udp {
 
     use bytes::BytesMut;
     use futures::{Future, Stream};
+    use futures::future::Executor;
+    use futures_cpupool::CpuPool;
     use tokio::net::{UdpCodec, UdpSocket};
     use tokio::reactor::Handle;
 
     pub fn connect(&addr: &SocketAddr,
                    handle: &Handle,
-                   stdin: Box<Stream<Item = Vec<u8>, Error = io::Error>>)
+                   pool: &CpuPool,
+                   stdin: Box<Stream<Item = Vec<u8>, Error = io::Error> + Send>)
         -> Box<Stream<Item = BytesMut, Error = io::Error>>
     {
         // We'll bind our UDP socket to a local IP/port, but for now we
@@ -193,14 +203,14 @@ mod udp {
 
         // All bytes from `stdin` will go to the `addr` specified in our
         // argument list. Like with TCP this is spawned concurrently
-        handle.spawn(stdin.map(move |chunk| {
+        pool.execute(stdin.map(move |chunk| {
             (addr, chunk)
         }).forward(sink).then(|result| {
             if let Err(e) = result {
                 panic!("failed to write to socket: {}", e)
             }
             Ok(())
-        }));
+        })).unwrap();
 
         // With UDP we could receive data from any source, so filter out
         // anything coming from a different address