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.

10 files changed, 96 insertions, 44 deletions

diff --git a/examples/chat.rs b/examples/chat.rs
index ff364476..a0023730 100644
--- a/examples/chat.rs
+++ b/examples/chat.rs
@@ -18,18 +18,20 @@
 //! messages.
 
 extern crate futures;
+extern crate futures_cpupool;
 extern crate tokio;
 extern crate tokio_io;
 
 use std::collections::HashMap;
-use std::rc::Rc;
-use std::cell::RefCell;
 use std::iter;
 use std::env;
 use std::io::{Error, ErrorKind, BufReader};
+use std::sync::{Arc, Mutex};
 
 use futures::Future;
+use futures::future::Executor;
 use futures::stream::{self, Stream};
+use futures_cpupool::CpuPool;
 use tokio::net::TcpListener;
 use tokio::reactor::Core;
 use tokio_io::io;
@@ -45,9 +47,10 @@ fn main() {
     let socket = TcpListener::bind(&addr, &handle).unwrap();
     println!("Listening on: {}", addr);
 
-    // This is a single-threaded server, so we can just use Rc and RefCell to
-    // store the map of all connections we know about.
-    let connections = Rc::new(RefCell::new(HashMap::new()));
+    // This is currently a multi threaded server.
+    //
+    // Once the same thread executor lands, transition to single threaded.
+    let connections = Arc::new(Mutex::new(HashMap::new()));
 
     let srv = socket.incoming().for_each(move |(stream, addr)| {
         println!("New Connection: {}", addr);
@@ -57,7 +60,7 @@ fn main() {
         // send us messages. Then register our address with the stream to send
         // data to us.
         let (tx, rx) = futures::sync::mpsc::unbounded();
-        connections.borrow_mut().insert(addr, tx);
+        connections.lock().unwrap().insert(addr, tx);
 
         // Define here what we do for the actual I/O. That is, read a bunch of
         // lines from the socket and dispatch them while we also write any lines
@@ -88,7 +91,7 @@ fn main() {
             let connections = connections_inner.clone();
             line.map(move |(reader, message)| {
                 println!("{}: {:?}", addr, message);
-                let mut conns = connections.borrow_mut();
+                let mut conns = connections.lock().unwrap();
                 if let Ok(msg) = message {
                     // For each open connection except the sender, send the
                     // string via the channel.
@@ -114,17 +117,19 @@ fn main() {
             amt.map_err(|_| ())
         });
 
+        let pool = CpuPool::new(1);
+
         // Now that we've got futures representing each half of the socket, we
         // use the `select` combinator to wait for either half to be done to
         // tear down the other. Then we spawn off the result.
         let connections = connections.clone();
         let socket_reader = socket_reader.map_err(|_| ());
         let connection = socket_reader.map(|_| ()).select(socket_writer.map(|_| ()));
-        handle.spawn(connection.then(move |_| {
-            connections.borrow_mut().remove(&addr);
+        pool.execute(connection.then(move |_| {
+            connections.lock().unwrap().remove(&addr);
             println!("Connection {} closed.", addr);
             Ok(())
-        }));
+        })).unwrap();
 
         Ok(())
     });
diff --git a/examples/compress.rs b/examples/compress.rs
index 6b0f1730..8fedf25e 100644
--- a/examples/compress.rs
+++ b/examples/compress.rs
@@ -29,6 +29,7 @@ use std::env;
 use std::net::SocketAddr;
 
 use futures::{Future, Stream, Poll};
+use futures::future::Executor;
 use futures_cpupool::CpuPool;
 use tokio::net::{TcpListener, TcpStream};
 use tokio::reactor::Core;
@@ -53,13 +54,13 @@ fn main() {
     // The compress logic will happen in the function below, but everything's
     // still a future! Each client is spawned to concurrently get processed.
     let server = socket.incoming().for_each(move |(socket, addr)| {
-        handle.spawn(compress(socket, &pool).then(move |result| {
+        pool.execute(compress(socket, &pool).then(move |result| {
             match result {
                 Ok((r, w)) => println!("{}: compressed {} bytes to {}", addr, r, w),
                 Err(e) => println!("{}: failed when compressing: {}", addr, e),
             }
             Ok(())
-        }));
+        })).unwrap();
         Ok(())
     });
 
@@ -70,7 +71,7 @@ fn main() {
 /// `socket` on the `pool` provided, writing it back out to `socket` as it's
 /// available.
 fn compress(socket: TcpStream, pool: &CpuPool)
-    -> Box<Future<Item = (u64, u64), Error = io::Error>>
+    -> Box<Future<Item = (u64, u64), Error = io::Error> + Send>
 {
     use tokio_io::io;
 
diff --git a/examples/connect.rs b/examples/connect.rs
index d5238a53..1c3fcb75 100644
--- a/examples/connect.rs
+++ b/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
diff --git a/examples/echo-threads.rs b/examples/echo-threads.rs
index 63ed47e4..4869d337 100644
--- a/examples/echo-threads.rs
+++ b/examples/echo-threads.rs
@@ -14,6 +14,7 @@
 //!     cargo run --example connect 127.0.0.1:8080
 
 extern crate futures;
+extern crate futures_cpupool;
 extern crate num_cpus;
 extern crate tokio;
 extern crate tokio_io;
@@ -23,8 +24,10 @@ use std::net::{self, SocketAddr};
 use std::thread;
 
 use futures::Future;
+use futures::future::Executor;
 use futures::stream::Stream;
 use futures::sync::mpsc;
+use futures_cpupool::CpuPool;
 use tokio_io::AsyncRead;
 use tokio_io::io::copy;
 use tokio::net::TcpStream;
@@ -69,6 +72,8 @@ fn worker(rx: mpsc::UnboundedReceiver<net::TcpStream>) {
     let mut core = Core::new().unwrap();
     let handle = core.handle();
 
+    let pool = CpuPool::new(1);
+
     let done = rx.for_each(move |socket| {
         // First up when we receive a socket we associate it with our event loop
         // using the `TcpStream::from_stream` API. After that the socket is not
@@ -92,7 +97,7 @@ fn worker(rx: mpsc::UnboundedReceiver<net::TcpStream>) {
 
             Ok(())
         });
-        handle.spawn(msg);
+        pool.execute(msg).unwrap();
 
         Ok(())
     });
diff --git a/examples/echo.rs b/examples/echo.rs
index 9abd9c38..fdf0e4cf 100644
--- a/examples/echo.rs
+++ b/examples/echo.rs
@@ -18,6 +18,7 @@
 //! should be able to see them all make progress simultaneously.
 
 extern crate futures;
+extern crate futures_cpupool;
 extern crate tokio;
 extern crate tokio_io;
 
@@ -25,7 +26,9 @@ use std::env;
 use std::net::SocketAddr;
 
 use futures::Future;
+use futures::future::Executor;
 use futures::stream::Stream;
+use futures_cpupool::CpuPool;
 use tokio_io::AsyncRead;
 use tokio_io::io::copy;
 use tokio::net::TcpListener;
@@ -46,7 +49,7 @@ fn main() {
     //
     // After the event loop is created we acquire a handle to it through the
     // `handle` method. With this handle we'll then later be able to create I/O
-    // objects and spawn futures.
+    // objects.
     let mut core = Core::new().unwrap();
     let handle = core.handle();
 
@@ -58,6 +61,9 @@ fn main() {
     let socket = TcpListener::bind(&addr, &handle).unwrap();
     println!("Listening on: {}", addr);
 
+    // A CpuPool allows futures to be executed concurrently.
+    let pool = CpuPool::new(1);
+
     // Here we convert the `TcpListener` to a stream of incoming connections
     // with the `incoming` method. We then define how to process each element in
     // the stream with the `for_each` method.
@@ -105,16 +111,16 @@ fn main() {
         // And this is where much of the magic of this server happens. We
         // crucially want all clients to make progress concurrently, rather than
         // blocking one on completion of another. To achieve this we use the
-        // `spawn` function on `Handle` to essentially execute some work in the
-        // background.
+        // `execute` function on the `Executor` trait to essentially execute
+        // some work in the background.
         //
         // This function will transfer ownership of the future (`msg` in this
         // case) to the event loop that `handle` points to. The event loop will
         // then drive the future to completion.
         //
-        // Essentially here we're spawning a new task to run concurrently, which
-        // will allow all of our clients to be processed concurrently.
-        handle.spawn(msg);
+        // Essentially here we're executing a new task to run concurrently,
+        // which will allow all of our clients to be processed concurrently.
+        pool.execute(msg).unwrap();
 
         Ok(())
     });
diff --git a/examples/proxy.rs b/examples/proxy.rs
index 05e4c0c3..14a63a7f 100644
--- a/examples/proxy.rs
+++ b/examples/proxy.rs
@@ -17,6 +17,7 @@
 //! the echo server, and you'll be able to see data flowing between them.
 
 extern crate futures;
+extern crate futures_cpupool;
 extern crate tokio;
 extern crate tokio_io;
 
@@ -27,6 +28,8 @@ use std::io::{self, Read, Write};
 
 use futures::stream::Stream;
 use futures::{Future, Poll};
+use futures::future::Executor;
+use futures_cpupool::CpuPool;
 use tokio::net::{TcpListener, TcpStream};
 use tokio::reactor::Core;
 use tokio_io::{AsyncRead, AsyncWrite};
@@ -43,6 +46,8 @@ fn main() {
     let mut l = Core::new().unwrap();
     let handle = l.handle();
 
+    let pool = CpuPool::new(1);
+
     // Create a TCP listener which will listen for incoming connections.
     let socket = TcpListener::bind(&listen_addr, &l.handle()).unwrap();
     println!("Listening on: {}", listen_addr);
@@ -88,7 +93,7 @@ fn main() {
             // Don't panic. Maybe the client just disconnected too soon.
             println!("error: {}", e);
         });
-        handle.spawn(msg);
+        pool.execute(msg).unwrap();
 
         Ok(())
     });
diff --git a/examples/sink.rs b/examples/sink.rs
index 5f42443b..fd1cd82b 100644
--- a/examples/sink.rs
+++ b/examples/sink.rs
@@ -17,6 +17,7 @@
 
 extern crate env_logger;
 extern crate futures;
+extern crate futures_cpupool;
 extern crate tokio;
 extern crate tokio_io;
 
@@ -25,7 +26,9 @@ use std::iter;
 use std::net::SocketAddr;
 
 use futures::Future;
+use futures::future::Executor;
 use futures::stream::{self, Stream};
+use futures_cpupool::CpuPool;
 use tokio_io::IoFuture;
 use tokio::net::{TcpListener, TcpStream};
 use tokio::reactor::Core;
@@ -35,13 +38,15 @@ fn main() {
     let addr = env::args().nth(1).unwrap_or("127.0.0.1:8080".to_string());
     let addr = addr.parse::<SocketAddr>().unwrap();
 
+    let pool = CpuPool::new(1);
+
     let mut core = Core::new().unwrap();
     let handle = core.handle();
     let socket = TcpListener::bind(&addr, &handle).unwrap();
     println!("Listening on: {}", addr);
     let server = socket.incoming().for_each(|(socket, addr)| {
         println!("got a socket: {}", addr);
-        handle.spawn(write(socket).or_else(|_| Ok(())));
+        pool.execute(write(socket).or_else(|_| Ok(()))).unwrap();
         Ok(())
     });
     core.run(server).unwrap();
diff --git a/examples/tinydb.rs b/examples/tinydb.rs
index 61d0fd62..bfb0d123 100644
--- a/examples/tinydb.rs
+++ b/examples/tinydb.rs
@@ -40,17 +40,19 @@
 //!   returning the previous value, if any.
 
 extern crate futures;
+extern crate futures_cpupool;
 extern crate tokio;
 extern crate tokio_io;
 
-use std::cell::RefCell;
 use std::collections::HashMap;
 use std::io::BufReader;
-use std::rc::Rc;
 use std::env;
 use std::net::SocketAddr;
+use std::sync::{Arc, Mutex};
 
 use futures::prelude::*;
+use futures::future::Executor;
+use futures_cpupool::CpuPool;
 use tokio::net::TcpListener;
 use tokio::reactor::Core;
 use tokio_io::AsyncRead;
@@ -58,10 +60,10 @@ use tokio_io::io::{lines, write_all};
 
 /// The in-memory database shared amongst all clients.
 ///
-/// This database will be shared via `Rc`, so to mutate the internal map we're
+/// This database will be shared via `Arc`, so to mutate the internal map we're
 /// also going to use a `RefCell` for interior mutability.
 struct Database {
-    map: RefCell<HashMap<String, String>>,
+    map: Mutex<HashMap<String, String>>,
 }
 
 /// Possible requests our clients can send us
@@ -87,15 +89,18 @@ fn main() {
     let listener = TcpListener::bind(&addr, &handle).expect("failed to bind");
     println!("Listening on: {}", addr);
 
+    // Create a CpuPool to execute tasks
+    let pool = CpuPool::new(1);
+
     // Create the shared state of this server that will be shared amongst all
     // clients. We populate the initial database and then create the `Database`
-    // structure. Note the usage of `Rc` here which will be used to ensure that
+    // structure. Note the usage of `Arc` here which will be used to ensure that
     // each independently spawned client will have a reference to the in-memory
     // database.
     let mut initial_db = HashMap::new();
     initial_db.insert("foo".to_string(), "bar".to_string());
-    let db = Rc::new(Database {
-        map: RefCell::new(initial_db),
+    let db = Arc::new(Database {
+        map: Mutex::new(initial_db),
     });
 
     let done = listener.incoming().for_each(move |(socket, _addr)| {
@@ -125,7 +130,7 @@ fn main() {
                 Err(e) => return Response::Error { msg: e },
             };
 
-            let mut db = db.map.borrow_mut();
+            let mut db = db.map.lock().unwrap();
             match request {
                 Request::Get { key } => {
                     match db.get(&key) {
@@ -154,7 +159,7 @@ fn main() {
         // runs concurrently with all other clients, for now ignoring any errors
         // that we see.
         let msg = writes.then(move |_| Ok(()));
-        handle.spawn(msg);
+        pool.execute(msg).unwrap();
         Ok(())
     });
 
diff --git a/examples/tinyhttp.rs b/examples/tinyhttp.rs
index 043e56d2..2dddaf08 100644
--- a/examples/tinyhttp.rs
+++ b/examples/tinyhttp.rs
@@ -13,6 +13,7 @@
 
 extern crate bytes;
 extern crate futures;
+extern crate futures_cpupool;
 extern crate http;
 extern crate httparse;
 extern crate num_cpus;
@@ -31,8 +32,10 @@ use std::thread;
 
 use bytes::BytesMut;
 use futures::future;
+use futures::future::Executor;
 use futures::sync::mpsc;
 use futures::{Stream, Future, Sink};
+use futures_cpupool::CpuPool;
 use http::{Request, Response, StatusCode};
 use http::header::HeaderValue;
 use tokio::net::TcpStream;
@@ -69,6 +72,8 @@ fn worker(rx: mpsc::UnboundedReceiver<net::TcpStream>) {
     let mut core = Core::new().unwrap();
     let handle = core.handle();
 
+    let pool = CpuPool::new(1);
+
     let done = rx.for_each(move |socket| {
         // Associate each socket we get with our local event loop, and then use
         // the codec support in the tokio-io crate to deal with discrete
@@ -80,10 +85,10 @@ fn worker(rx: mpsc::UnboundedReceiver<net::TcpStream>) {
             let (tx, rx) = socket.framed(Http).split();
             tx.send_all(rx.and_then(respond))
         });
-        handle.spawn(req.then(move |result| {
+        pool.execute(req.then(move |result| {
             drop(result);
             Ok(())
-        }));
+        })).unwrap();
         Ok(())
     });
     core.run(done).unwrap();
@@ -95,7 +100,7 @@ fn worker(rx: mpsc::UnboundedReceiver<net::TcpStream>) {
 /// represents the various handling a server might do. Currently the contents
 /// here are pretty uninteresting.
 fn respond(req: Request<()>)
-    -> Box<Future<Item = Response<String>, Error = io::Error>>
+    -> Box<Future<Item = Response<String>, Error = io::Error> + Send>
 {
     let mut ret = Response::builder();
     let body = match req.uri().path() {
diff --git a/examples/udp-codec.rs b/examples/udp-codec.rs
index 4066060e..65a522ca 100644
--- a/examples/udp-codec.rs
+++ b/examples/udp-codec.rs
@@ -9,11 +9,14 @@
 extern crate tokio;
 extern crate env_logger;
 extern crate futures;
+extern crate futures_cpupool;
 
 use std::io;
 use std::net::SocketAddr;
 
 use futures::{Future, Stream, Sink};
+use futures::future::Executor;
+use futures_cpupool::CpuPool;
 use tokio::net::{UdpSocket, UdpCodec};
 use tokio::reactor::Core;
 
@@ -39,6 +42,8 @@ fn main() {
     let mut core = Core::new().unwrap();
     let handle = core.handle();
 
+    let pool = CpuPool::new(1);
+
     let addr: SocketAddr = "127.0.0.1:0".parse().unwrap();
 
     // Bind both our sockets and then figure out what ports we got.
@@ -73,6 +78,6 @@ fn main() {
     let b = b_sink.send_all(b_stream);
 
     // Spawn the sender of pongs and then wait for our pinger to finish.
-    handle.spawn(b.then(|_| Ok(())));
+    pool.execute(b.then(|_| Ok(()))).unwrap();
     drop(core.run(a));
 }