rt: switch io::handle refs with scheduler:Handle (#5128)

The `schedule::Handle` reference is the internal runtime handle. This
patch replaces owned refs to `runtime::io::Handle` with
`scheduler::Handle`.

tokio/src/io/async_fd.rs

@@ -1,5 +1,6 @@
 use crate::io::Interest;
-use crate::runtime::io::{Handle, ReadyEvent, Registration};
+use crate::runtime::io::{ReadyEvent, Registration};
+use crate::runtime::scheduler;
 
 use mio::unix::SourceFd;
 use std::io;
@@ -200,12 +201,13 @@ impl<T: AsRawFd> AsyncFd<T> {
     where
         T: AsRawFd,
     {
-        Self::new_with_handle_and_interest(inner, Handle::current(), interest)
+        Self::new_with_handle_and_interest(inner, scheduler::Handle::current(), interest)
     }
 
+    #[track_caller]
     pub(crate) fn new_with_handle_and_interest(
         inner: T,
-        handle: Handle,
+        handle: scheduler::Handle,
         interest: Interest,
     ) -> io::Result<Self> {
         let fd = inner.as_raw_fd();

tokio/src/io/bsd/poll_aio.rs

@@ -1,7 +1,8 @@
 //! Use POSIX AIO futures with Tokio.
 
 use crate::io::interest::Interest;
-use crate::runtime::io::{Handle, ReadyEvent, Registration};
+use crate::runtime::io::{ReadyEvent, Registration};
+use crate::runtime::scheduler;
 use mio::event::Source;
 use mio::Registry;
 use mio::Token;
@@ -118,7 +119,7 @@ impl<E: AioSource> Aio<E> {
 
     fn new_with_interest(io: E, interest: Interest) -> io::Result<Self> {
         let mut io = MioSource(io);
-        let handle = Handle::current();
+        let handle = scheduler::Handle::current();
         let registration = Registration::new_with_interest_and_handle(&mut io, interest, handle)?;
         Ok(Self { io, registration })
     }

tokio/src/io/poll_evented.rs

@@ -1,5 +1,6 @@
 use crate::io::interest::Interest;
-use crate::runtime::io::{Handle, Registration};
+use crate::runtime::io::Registration;
+use crate::runtime::scheduler;
 
 use mio::event::Source;
 use std::fmt;
@@ -103,13 +104,14 @@ impl<E: Source> PollEvented<E> {
     #[track_caller]
     #[cfg_attr(feature = "signal", allow(unused))]
     pub(crate) fn new_with_interest(io: E, interest: Interest) -> io::Result<Self> {
-        Self::new_with_interest_and_handle(io, interest, Handle::current())
+        Self::new_with_interest_and_handle(io, interest, scheduler::Handle::current())
     }
 
+    #[track_caller]
     pub(crate) fn new_with_interest_and_handle(
         mut io: E,
         interest: Interest,
-        handle: Handle,
+        handle: scheduler::Handle,
     ) -> io::Result<Self> {
         let registration = Registration::new_with_interest_and_handle(&mut io, interest, handle)?;
         Ok(Self {

tokio/src/runtime/context.rs

@@ -24,24 +24,6 @@ pub(crate) fn current() -> Handle {
     }
 }
 
-cfg_io_driver! {
-    #[track_caller]
-    pub(crate) fn io_handle() -> crate::runtime::driver::IoHandle {
-        match CONTEXT.try_with(|ctx| {
-            let ctx = ctx.borrow();
-            ctx.as_ref()
-                .expect(crate::util::error::CONTEXT_MISSING_ERROR)
-                .inner
-                .driver()
-                .io
-                .clone()
-        }) {
-            Ok(io_handle) => io_handle,
-            Err(_) => panic!("{}", crate::util::error::THREAD_LOCAL_DESTROYED_ERROR),
-        }
-    }
-}
-
 cfg_signal_internal! {
     #[cfg(unix)]
     pub(crate) fn signal_handle() -> crate::runtime::driver::SignalHandle {

tokio/src/runtime/driver.rs

@@ -82,10 +82,11 @@ impl Handle {
     }
 
     cfg_io_driver! {
+        #[track_caller]
         pub(crate) fn io(&self) -> &crate::runtime::io::Handle {
             self.io
                 .as_ref()
-                .expect("A Tokio 1.x context was found, but I/O is disabled. Call `enable_io` on the runtime builder to enable I/O.")
+                .expect("A Tokio 1.x context was found, but IO is disabled. Call `enable_io` on the runtime builder to enable IO.")
         }
     }
 
@@ -170,14 +171,6 @@ cfg_io_driver! {
             }
         }
 
-        #[track_caller]
-        pub(crate) fn expect(self, msg: &'static str) -> crate::runtime::io::Handle {
-            match self {
-                IoHandle::Enabled(v) => v,
-                IoHandle::Disabled(..) => panic!("{}", msg),
-            }
-        }
-
         pub(crate) fn as_ref(&self) -> Option<&crate::runtime::io::Handle> {
             match self {
                 IoHandle::Enabled(v) => Some(v),

tokio/src/runtime/handle.rs

@@ -96,7 +96,9 @@ impl Handle {
     /// ```
     #[track_caller]
     pub fn current() -> Self {
-        context::current()
+        Handle {
+            inner: scheduler::Handle::current(),
+        }
     }
 
     /// Returns a Handle view over the currently running Runtime

tokio/src/runtime/io/mod.rs

@@ -236,38 +236,6 @@ impl fmt::Debug for Driver {
     }
 }
 
-// ===== impl Handle =====
-
-cfg_rt! {
-    impl Handle {
-        /// Returns a handle to the current reactor.
-        ///
-        /// # Panics
-        ///
-        /// This function panics if there is no current reactor set and `rt` feature
-        /// flag is not enabled.
-        #[track_caller]
-        pub(crate) fn current() -> Self {
-            crate::runtime::context::io_handle().expect("A Tokio 1.x context was found, but IO is disabled. Call `enable_io` on the runtime builder to enable IO.")
-        }
-    }
-}
-
-cfg_not_rt! {
-    impl Handle {
-        /// Returns a handle to the current reactor.
-        ///
-        /// # Panics
-        ///
-        /// This function panics if there is no current reactor set, or if the `rt`
-        /// feature flag is not enabled.
-        #[track_caller]
-        pub(crate) fn current() -> Self {
-            panic!("{}", crate::util::error::CONTEXT_MISSING_ERROR)
-        }
-    }
-}
-
 cfg_net! {
     cfg_metrics! {
         impl Handle {

tokio/src/runtime/io/registration.rs

@@ -2,6 +2,7 @@
 
 use crate::io::interest::Interest;
 use crate::runtime::io::{Direction, Handle, ReadyEvent, ScheduledIo};
+use crate::runtime::scheduler;
 use crate::util::slab;
 
 use mio::event::Source;
@@ -43,8 +44,8 @@ cfg_io_driver! {
     /// [`poll_write_ready`]: method@Self::poll_write_ready`
     #[derive(Debug)]
     pub(crate) struct Registration {
-        /// Handle to the associated driver.
-        handle: Handle,
+        /// Handle to the associated runtime.
+        handle: scheduler::Handle,
 
         /// Reference to state stored by the driver.
         shared: slab::Ref<ScheduledIo>,
@@ -66,12 +67,13 @@ impl Registration {
     ///
     /// - `Ok` if the registration happened successfully
     /// - `Err` if an error was encountered during registration
+    #[track_caller]
     pub(crate) fn new_with_interest_and_handle(
         io: &mut impl Source,
         interest: Interest,
-        handle: Handle,
+        handle: scheduler::Handle,
     ) -> io::Result<Registration> {
-        let shared = handle.inner.add_source(io, interest)?;
+        let shared = handle.io().inner.add_source(io, interest)?;
 
         Ok(Registration { handle, shared })
     }
@@ -93,7 +95,7 @@ impl Registration {
     ///
     /// `Err` is returned if an error is encountered.
     pub(crate) fn deregister(&mut self, io: &mut impl Source) -> io::Result<()> {
-        self.handle.inner.deregister_source(io)
+        self.handle().inner.deregister_source(io)
     }
 
     pub(crate) fn clear_readiness(&self, event: ReadyEvent) {
@@ -146,7 +148,7 @@ impl Registration {
         let coop = ready!(crate::coop::poll_proceed(cx));
         let ev = ready!(self.shared.poll_readiness(cx, direction));
 
-        if self.handle.inner.is_shutdown() {
+        if self.handle().inner.is_shutdown() {
             return Poll::Ready(Err(gone()));
         }
 
@@ -195,6 +197,10 @@ impl Registration {
             res => res,
         }
     }
+
+    fn handle(&self) -> &Handle {
+        self.handle.io()
+    }
 }
 
 impl Drop for Registration {
@@ -224,7 +230,7 @@ cfg_io_readiness! {
             pin!(fut);
 
             crate::future::poll_fn(|cx| {
-                if self.handle.inner.is_shutdown() {
+                if self.handle().inner.is_shutdown() {
                     return Poll::Ready(Err(io::Error::new(
                         io::ErrorKind::Other,
                         crate::util::error::RUNTIME_SHUTTING_DOWN_ERROR

tokio/src/runtime/scheduler/mod.rs

@@ -40,6 +40,13 @@ impl Handle {
         }
     }
 
+    cfg_io_driver! {
+        #[track_caller]
+        pub(crate) fn io(&self) -> &crate::runtime::io::Handle {
+            self.driver().io()
+        }
+    }
+
     cfg_time! {
         #[track_caller]
         pub(crate) fn time(&self) -> &crate::runtime::time::Handle {
@@ -62,6 +69,11 @@ cfg_rt! {
     use crate::util::RngSeedGenerator;
 
     impl Handle {
+        #[track_caller]
+        pub(crate) fn current() -> Handle {
+            crate::runtime::context::current().inner
+        }
+
         pub(crate) fn blocking_spawner(&self) -> &blocking::Spawner {
             match self {
                 Handle::CurrentThread(h) => &h.blocking_spawner,
@@ -156,3 +168,12 @@ cfg_rt! {
         }
     }
 }
+
+cfg_not_rt! {
+    impl Handle {
+        #[track_caller]
+        pub(crate) fn current() -> Handle {
+            panic!("{}", crate::util::error::CONTEXT_MISSING_ERROR)
+        }
+    }
+}