signal: refactor Windows registrations to be lazy (#1001)

- Use `Handle::default` over `Handle::current` for consistent semantics
- Make all `windows::Event` constructors lazily invoke `global_init`
  so they can be safely constructed off-task
- Don't assume the reactor is alive and event registration will be done
  when calling `global_init`

Add windows regression tests. Unfortunately, Windows doesn't have a
reliable way of programmatically sending CTRL_C or CTRL_BREAK events
to a progress, so the tests can only exercise our internal machinery by
invoking the handler that we register with the OS

Fixes #999

4 files changed, 121 insertions, 53 deletions

diff --git a/tokio-signal/CHANGELOG.md b/tokio-signal/CHANGELOG.md
index 56920565..5014fb4d 100644
--- a/tokio-signal/CHANGELOG.md
+++ b/tokio-signal/CHANGELOG.md
@@ -1,3 +1,11 @@
+# 0.2.9
+
+### Fixed
+- `windows::Event` performs internal registrations lazily, so now it can be
+constructed outside of a running task
+- remove usage of deprecated `Handle::current` in default `windows::Event`
+constructors
+
 # 0.2.8 (March 22, 2019)
 
 ### Fixed
diff --git a/tokio-signal/Cargo.toml b/tokio-signal/Cargo.toml
index e6ec22a3..275aefd4 100644
--- a/tokio-signal/Cargo.toml
+++ b/tokio-signal/Cargo.toml
@@ -38,4 +38,4 @@ tokio = "0.1.8"
 
 [target.'cfg(windows)'.dependencies.winapi]
 version = "0.3"
-features = ["minwindef", "wincon"]
+features = ["consoleapi", "minwindef", "wincon"]
diff --git a/tokio-signal/examples/ctrl-c.rs b/tokio-signal/examples/ctrl-c.rs
index 45ad82b9..6d6adfd7 100644
--- a/tokio-signal/examples/ctrl-c.rs
+++ b/tokio-signal/examples/ctrl-c.rs
@@ -53,7 +53,12 @@ fn main() -> Result<(), Box<std::error::Error>> {
     // Up until now, we haven't really DONE anything, just prepared
     // now it's time to actually schedule, and thus execute, the stream
     // on our event loop
-    tokio::runtime::current_thread::block_on_all(future)?;
+    // FIXME(1000): windows uses a global driver task which doesn't terminate
+    // on its own, so if we use block_on_all our application will never exit
+    //tokio::runtime::current_thread::block_on_all(future)?;
+    tokio::runtime::current_thread::Runtime::new()
+        .expect("failed to start runtime on current thread")
+        .block_on(future)?;
 
     println!("Stream ended, quiting the program.");
     Ok(())
diff --git a/tokio-signal/src/windows.rs b/tokio-signal/src/windows.rs
index c30f8736..8e1cd49e 100644
--- a/tokio-signal/src/windows.rs
+++ b/tokio-signal/src/windows.rs
@@ -16,21 +16,18 @@ use std::sync::atomic::{AtomicBool, Ordering};
 use std::sync::{Once, ONCE_INIT};
 
 use self::winapi::shared::minwindef::*;
+use self::winapi::um::consoleapi::SetConsoleCtrlHandler;
 use self::winapi::um::wincon::*;
 use futures::future;
 use futures::stream::Fuse;
 use futures::sync::mpsc;
 use futures::sync::oneshot;
-use futures::{Async, Future, IntoFuture, Poll, Stream};
+use futures::{Async, Future, Poll, Stream};
 use mio::Ready;
 use tokio_reactor::{Handle, PollEvented};
 
 use IoFuture;
 
-extern "system" {
-    fn SetConsoleCtrlHandler(HandlerRoutine: usize, Add: BOOL) -> BOOL;
-}
-
 static INIT: Once = ONCE_INIT;
 static mut GLOBAL_STATE: *mut GlobalState = 0 as *mut _;
 
@@ -85,7 +82,7 @@ impl Event {
     /// This function will register a handler via `SetConsoleCtrlHandler` and
     /// deliver notifications to the returned stream.
     pub fn ctrl_c() -> IoFuture<Event> {
-        Event::ctrl_c_handle(&Handle::current())
+        Event::ctrl_c_handle(&Handle::default())
     }
 
     /// Creates a new stream listening for the `CTRL_C_EVENT` events.
@@ -101,7 +98,7 @@ impl Event {
     /// This function will register a handler via `SetConsoleCtrlHandler` and
     /// deliver notifications to the returned stream.
     pub fn ctrl_break() -> IoFuture<Event> {
-        Event::ctrl_break_handle(&Handle::current())
+        Event::ctrl_break_handle(&Handle::default())
     }
 
     /// Creates a new stream listening for the `CTRL_BREAK_EVENT` events.
@@ -113,11 +110,17 @@ impl Event {
     }
 
     fn new(signum: DWORD, handle: &Handle) -> IoFuture<Event> {
-        let mut init = None;
-        INIT.call_once(|| {
-            init = Some(global_init(handle));
-        });
-        let new_signal = future::lazy(move || {
+        let handle = handle.clone();
+        let new_signal = future::poll_fn(move || {
+            let mut init = None;
+            INIT.call_once(|| {
+                init = Some(global_init(&handle));
+            });
+
+            if let Some(Err(e)) = init {
+                return Err(e);
+            }
+
             let (tx, rx) = oneshot::channel();
             let msg = Message::NewEvent(signum, tx);
             let res = unsafe { (*GLOBAL_STATE).tx.clone().unbounded_send(msg) };
@@ -125,12 +128,10 @@ impl Event {
                 "failed to request a new signal stream, did the \
                  first event loop go away?",
             );
-            rx.then(|r| r.unwrap())
+            Ok(Async::Ready(rx.then(|r| r.unwrap())))
         });
-        match init {
-            Some(init) => Box::new(init.into_future().and_then(|()| new_signal)),
-            None => Box::new(new_signal),
-        }
+
+        Box::new(new_signal.flatten())
     }
 }
 
@@ -145,11 +146,7 @@ impl Stream for Event {
         self.reg.clear_read_ready(Ready::readable())?;
         self.reg
             .get_ref()
-            .inner
-            .borrow()
-            .as_ref()
-            .unwrap()
-            .1
+            .readiness
             .set_readiness(mio::Ready::empty())
             .expect("failed to set readiness");
         Ok(Async::Ready(Some(())))
@@ -157,12 +154,12 @@ impl Stream for Event {
 }
 
 fn global_init(handle: &Handle) -> io::Result<()> {
+    let reg = MyRegistration::new();
+    let ready = reg.readiness.clone();
+
     let (tx, rx) = mpsc::unbounded();
-    let reg = MyRegistration {
-        inner: RefCell::new(None),
-    };
     let reg = try!(PollEvented::new_with_handle(reg, handle));
-    let ready = reg.get_ref().inner.borrow().as_ref().unwrap().1.clone();
+
     unsafe {
         let state = Box::new(GlobalState {
             ready: ready,
@@ -176,7 +173,7 @@ fn global_init(handle: &Handle) -> io::Result<()> {
         });
         GLOBAL_STATE = Box::into_raw(state);
 
-        let rc = SetConsoleCtrlHandler(handler as usize, TRUE);
+        let rc = SetConsoleCtrlHandler(Some(handler), TRUE);
         if rc == 0 {
             Box::from_raw(GLOBAL_STATE);
             GLOBAL_STATE = 0 as *mut _;
@@ -238,9 +235,9 @@ impl DriverTask {
 
             // Acquire the (registration, set_readiness) pair by... assuming
             // we're on the event loop (true because of the spawn above).
-            let reg = MyRegistration {
-                inner: RefCell::new(None),
-            };
+            let reg = MyRegistration::new();
+            let ready = reg.readiness.clone();
+
             let reg = match PollEvented::new_with_handle(reg, &self.handle) {
                 Ok(reg) => reg,
                 Err(e) => {
@@ -252,7 +249,6 @@ impl DriverTask {
             // Create the `Event` to pass back and then also keep a handle to
             // the `SetReadiness` for ourselves internally.
             let (tx, rx) = oneshot::channel();
-            let ready = reg.get_ref().inner.borrow_mut().as_mut().unwrap().1.clone();
             drop(complete.send(Ok(Event {
                 reg: reg,
                 _finished: tx,
@@ -268,13 +264,9 @@ impl DriverTask {
         self.reg.clear_read_ready(Ready::readable())?;
         self.reg
             .get_ref()
-            .inner
-            .borrow()
-            .as_ref()
-            .unwrap()
-            .1
+            .readiness
             .set_readiness(mio::Ready::empty())
-            .unwrap();
+            .expect("failed to set readiness");
 
         if unsafe { (*GLOBAL_STATE).ctrl_c.ready.swap(false, Ordering::SeqCst) } {
             for task in self.ctrl_c.tasks.iter() {
@@ -305,15 +297,27 @@ unsafe extern "system" fn handler(ty: DWORD) -> BOOL {
         FALSE
     } else {
         drop((*GLOBAL_STATE).ready.set_readiness(mio::Ready::readable()));
-        // TODO: this will report that we handled a CTRL_BREAK_EVENT when in
-        //       fact we may not have any streams actually created for that
+        // TODO(1000): this will report that we handled a CTRL_BREAK_EVENT when
+        //       in fact we may not have any streams actually created for that
         //       event.
         TRUE
     }
 }
 
 struct MyRegistration {
-    inner: RefCell<Option<(mio::Registration, mio::SetReadiness)>>,
+    registration: mio::Registration,
+    readiness: mio::SetReadiness,
+}
+
+impl MyRegistration {
+    fn new() -> Self {
+        let (registration, readiness) = mio::Registration::new2();
+
+        Self {
+            registration,
+            readiness,
+        }
+    }
 }
 
 impl mio::Evented for MyRegistration {
@@ -324,23 +328,74 @@ impl mio::Evented for MyRegistration {
         events: mio::Ready,
         opts: mio::PollOpt,
     ) -> io::Result<()> {
-        let reg = mio::Registration::new2();
-        reg.0.register(poll, token, events, opts)?;
-        *self.inner.borrow_mut() = Some(reg);
-        Ok(())
+        self.registration.register(poll, token, events, opts)
     }
 
     fn reregister(
         &self,
-        _poll: &mio::Poll,
-        _token: mio::Token,
-        _events: mio::Ready,
-        _opts: mio::PollOpt,
+        poll: &mio::Poll,
+        token: mio::Token,
+        events: mio::Ready,
+        opts: mio::PollOpt,
     ) -> io::Result<()> {
-        Ok(())
+        self.registration.reregister(poll, token, events, opts)
     }
 
-    fn deregister(&self, _poll: &mio::Poll) -> io::Result<()> {
-        Ok(())
+    fn deregister(&self, poll: &mio::Poll) -> io::Result<()> {
+        mio::Evented::deregister(&self.registration, poll)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    extern crate tokio;
+
+    use self::tokio::runtime::current_thread;
+    use self::tokio::timer::Timeout;
+    use super::*;
+    use std::time::Duration;
+
+    fn with_timeout<F: Future>(future: F) -> impl Future<Item = F::Item, Error = F::Error> {
+        Timeout::new(future, Duration::from_secs(1)).map_err(|e| {
+            if e.is_timer() {
+                panic!("failed to register timer");
+            } else if e.is_elapsed() {
+                panic!("timed out")
+            } else {
+                e.into_inner().expect("missing inner error")
+            }
+        })
+    }
+
+    #[test]
+    fn ctrl_c_and_ctrl_break() {
+        // FIXME(1000): combining into one test due to a restriction where the
+        // first event loop cannot go away
+        let mut rt = current_thread::Runtime::new().unwrap();
+        let event_ctrl_c = rt
+            .block_on(with_timeout(Event::ctrl_c()))
+            .expect("failed to run future");
+
+        // Windows doesn't have a good programmatic way of sending events
+        // like sending signals on Unix, so we'll stub out the actual OS
+        // integration and test that our handling works.
+        unsafe {
+            super::handler(CTRL_C_EVENT);
+        }
+
+        rt.block_on(with_timeout(event_ctrl_c.into_future()))
+            .ok()
+            .expect("failed to run event");
+
+        let event_ctrl_break = rt
+            .block_on(with_timeout(Event::ctrl_break()))
+            .expect("failed to run future");
+        unsafe {
+            super::handler(CTRL_BREAK_EVENT);
+        }
+
+        rt.block_on(with_timeout(event_ctrl_break.into_future()))
+            .ok()
+            .expect("failed to run event");
     }
 }