Make IO thread-safe.

Each IO handle has a home event loop, which created it.
When a task wants to use an IO handle, it must first make sure it is on that home event loop.
It uses the scheduler handle in the IO handle to send itself there before starting the IO action.
Once the IO action completes, the task restores its previous home state.
If it is an AnySched task, then it will be executed on the new scheduler.
If it has a normal home, then it will return there before executing any more code after the IO action.

src/libstd/rt/io/timer.rs

@@ -41,7 +41,7 @@ impl Timer {
 }
 
 impl RtioTimer for Timer {
-    fn sleep(&self, msecs: u64) {
+    fn sleep(&mut self, msecs: u64) {
         (**self).sleep(msecs);
     }
 }
@@ -50,15 +50,11 @@ impl RtioTimer for Timer {
 mod test {
     use super::*;
     use rt::test::*;
-    use option::{Some, None};
     #[test]
     fn test_io_timer_sleep_simple() {
         do run_in_newsched_task {
             let timer = Timer::new();
-            match timer {
-                Some(t) => t.sleep(1),
-                None => assert!(false)
-            }
+            do timer.map_move |mut t| { t.sleep(1) };
         }
     }
-}
+}

src/libstd/rt/rtio.rs

@@ -22,7 +22,7 @@ pub type RemoteCallbackObject = uvio::UvRemoteCallback;
 pub type IoFactoryObject = uvio::UvIoFactory;
 pub type RtioTcpStreamObject = uvio::UvTcpStream;
 pub type RtioTcpListenerObject = uvio::UvTcpListener;
-pub type RtioUdpSocketObject = uvio::HomedUvUdpSocket; //uvio::UvUdpSocket;
+pub type RtioUdpSocketObject = uvio::UvUdpSocket;
 pub type RtioTimerObject = uvio::UvTimer;
 
 pub trait EventLoop {
@@ -88,5 +88,5 @@ pub trait RtioUdpSocket : RtioSocket {
 }
 
 pub trait RtioTimer {
-    fn sleep(&self, msecs: u64);
+    fn sleep(&mut self, msecs: u64);
 }