diff options
Diffstat (limited to 'third_party/rust/tokio/src/io/async_fd.rs')
| -rw-r--r-- | third_party/rust/tokio/src/io/async_fd.rs | 660 |
1 files changed, 660 insertions, 0 deletions
diff --git a/third_party/rust/tokio/src/io/async_fd.rs b/third_party/rust/tokio/src/io/async_fd.rs new file mode 100644 index 0000000000..93f9cb458a --- /dev/null +++ b/third_party/rust/tokio/src/io/async_fd.rs @@ -0,0 +1,660 @@ +use crate::io::driver::{Handle, Interest, ReadyEvent, Registration}; + +use mio::unix::SourceFd; +use std::io; +use std::os::unix::io::{AsRawFd, RawFd}; +use std::{task::Context, task::Poll}; + +/// Associates an IO object backed by a Unix file descriptor with the tokio +/// reactor, allowing for readiness to be polled. The file descriptor must be of +/// a type that can be used with the OS polling facilities (ie, `poll`, `epoll`, +/// `kqueue`, etc), such as a network socket or pipe, and the file descriptor +/// must have the nonblocking mode set to true. +/// +/// Creating an AsyncFd registers the file descriptor with the current tokio +/// Reactor, allowing you to directly await the file descriptor being readable +/// or writable. Once registered, the file descriptor remains registered until +/// the AsyncFd is dropped. +/// +/// The AsyncFd takes ownership of an arbitrary object to represent the IO +/// object. It is intended that this object will handle closing the file +/// descriptor when it is dropped, avoiding resource leaks and ensuring that the +/// AsyncFd can clean up the registration before closing the file descriptor. +/// The [`AsyncFd::into_inner`] function can be used to extract the inner object +/// to retake control from the tokio IO reactor. +/// +/// The inner object is required to implement [`AsRawFd`]. This file descriptor +/// must not change while [`AsyncFd`] owns the inner object, i.e. the +/// [`AsRawFd::as_raw_fd`] method on the inner type must always return the same +/// file descriptor when called multiple times. Failure to uphold this results +/// in unspecified behavior in the IO driver, which may include breaking +/// notifications for other sockets/etc. +/// +/// Polling for readiness is done by calling the async functions [`readable`] +/// and [`writable`]. These functions complete when the associated readiness +/// condition is observed. Any number of tasks can query the same `AsyncFd` in +/// parallel, on the same or different conditions. +/// +/// On some platforms, the readiness detecting mechanism relies on +/// edge-triggered notifications. This means that the OS will only notify Tokio +/// when the file descriptor transitions from not-ready to ready. For this to +/// work you should first try to read or write and only poll for readiness +/// if that fails with an error of [`std::io::ErrorKind::WouldBlock`]. +/// +/// Tokio internally tracks when it has received a ready notification, and when +/// readiness checking functions like [`readable`] and [`writable`] are called, +/// if the readiness flag is set, these async functions will complete +/// immediately. This however does mean that it is critical to ensure that this +/// ready flag is cleared when (and only when) the file descriptor ceases to be +/// ready. The [`AsyncFdReadyGuard`] returned from readiness checking functions +/// serves this function; after calling a readiness-checking async function, +/// you must use this [`AsyncFdReadyGuard`] to signal to tokio whether the file +/// descriptor is no longer in a ready state. +/// +/// ## Use with to a poll-based API +/// +/// In some cases it may be desirable to use `AsyncFd` from APIs similar to +/// [`TcpStream::poll_read_ready`]. The [`AsyncFd::poll_read_ready`] and +/// [`AsyncFd::poll_write_ready`] functions are provided for this purpose. +/// Because these functions don't create a future to hold their state, they have +/// the limitation that only one task can wait on each direction (read or write) +/// at a time. +/// +/// # Examples +/// +/// This example shows how to turn [`std::net::TcpStream`] asynchronous using +/// `AsyncFd`. It implements `read` as an async fn, and `AsyncWrite` as a trait +/// to show how to implement both approaches. +/// +/// ```no_run +/// use futures::ready; +/// use std::io::{self, Read, Write}; +/// use std::net::TcpStream; +/// use std::pin::Pin; +/// use std::task::{Context, Poll}; +/// use tokio::io::AsyncWrite; +/// use tokio::io::unix::AsyncFd; +/// +/// pub struct AsyncTcpStream { +/// inner: AsyncFd<TcpStream>, +/// } +/// +/// impl AsyncTcpStream { +/// pub fn new(tcp: TcpStream) -> io::Result<Self> { +/// tcp.set_nonblocking(true)?; +/// Ok(Self { +/// inner: AsyncFd::new(tcp)?, +/// }) +/// } +/// +/// pub async fn read(&self, out: &mut [u8]) -> io::Result<usize> { +/// loop { +/// let mut guard = self.inner.readable().await?; +/// +/// match guard.try_io(|inner| inner.get_ref().read(out)) { +/// Ok(result) => return result, +/// Err(_would_block) => continue, +/// } +/// } +/// } +/// } +/// +/// impl AsyncWrite for AsyncTcpStream { +/// fn poll_write( +/// self: Pin<&mut Self>, +/// cx: &mut Context<'_>, +/// buf: &[u8] +/// ) -> Poll<io::Result<usize>> { +/// loop { +/// let mut guard = ready!(self.inner.poll_write_ready(cx))?; +/// +/// match guard.try_io(|inner| inner.get_ref().write(buf)) { +/// Ok(result) => return Poll::Ready(result), +/// Err(_would_block) => continue, +/// } +/// } +/// } +/// +/// fn poll_flush( +/// self: Pin<&mut Self>, +/// cx: &mut Context<'_>, +/// ) -> Poll<io::Result<()>> { +/// // tcp flush is a no-op +/// Poll::Ready(Ok(())) +/// } +/// +/// fn poll_shutdown( +/// self: Pin<&mut Self>, +/// cx: &mut Context<'_>, +/// ) -> Poll<io::Result<()>> { +/// self.inner.get_ref().shutdown(std::net::Shutdown::Write)?; +/// Poll::Ready(Ok(())) +/// } +/// } +/// ``` +/// +/// [`readable`]: method@Self::readable +/// [`writable`]: method@Self::writable +/// [`AsyncFdReadyGuard`]: struct@self::AsyncFdReadyGuard +/// [`TcpStream::poll_read_ready`]: struct@crate::net::TcpStream +pub struct AsyncFd<T: AsRawFd> { + registration: Registration, + inner: Option<T>, +} + +/// Represents an IO-ready event detected on a particular file descriptor that +/// has not yet been acknowledged. This is a `must_use` structure to help ensure +/// that you do not forget to explicitly clear (or not clear) the event. +/// +/// This type exposes an immutable reference to the underlying IO object. +#[must_use = "You must explicitly choose whether to clear the readiness state by calling a method on ReadyGuard"] +pub struct AsyncFdReadyGuard<'a, T: AsRawFd> { + async_fd: &'a AsyncFd<T>, + event: Option<ReadyEvent>, +} + +/// Represents an IO-ready event detected on a particular file descriptor that +/// has not yet been acknowledged. This is a `must_use` structure to help ensure +/// that you do not forget to explicitly clear (or not clear) the event. +/// +/// This type exposes a mutable reference to the underlying IO object. +#[must_use = "You must explicitly choose whether to clear the readiness state by calling a method on ReadyGuard"] +pub struct AsyncFdReadyMutGuard<'a, T: AsRawFd> { + async_fd: &'a mut AsyncFd<T>, + event: Option<ReadyEvent>, +} + +const ALL_INTEREST: Interest = Interest::READABLE.add(Interest::WRITABLE); + +impl<T: AsRawFd> AsyncFd<T> { + #[inline] + /// Creates an AsyncFd backed by (and taking ownership of) an object + /// implementing [`AsRawFd`]. The backing file descriptor is cached at the + /// time of creation. + /// + /// This method must be called in the context of a tokio runtime. + pub fn new(inner: T) -> io::Result<Self> + where + T: AsRawFd, + { + Self::with_interest(inner, ALL_INTEREST) + } + + #[inline] + /// Creates new instance as `new` with additional ability to customize interest, + /// allowing to specify whether file descriptor will be polled for read, write or both. + pub fn with_interest(inner: T, interest: Interest) -> io::Result<Self> + where + T: AsRawFd, + { + Self::new_with_handle_and_interest(inner, Handle::current(), interest) + } + + pub(crate) fn new_with_handle_and_interest( + inner: T, + handle: Handle, + interest: Interest, + ) -> io::Result<Self> { + let fd = inner.as_raw_fd(); + + let registration = + Registration::new_with_interest_and_handle(&mut SourceFd(&fd), interest, handle)?; + + Ok(AsyncFd { + registration, + inner: Some(inner), + }) + } + + /// Returns a shared reference to the backing object of this [`AsyncFd`]. + #[inline] + pub fn get_ref(&self) -> &T { + self.inner.as_ref().unwrap() + } + + /// Returns a mutable reference to the backing object of this [`AsyncFd`]. + #[inline] + pub fn get_mut(&mut self) -> &mut T { + self.inner.as_mut().unwrap() + } + + fn take_inner(&mut self) -> Option<T> { + let fd = self.inner.as_ref().map(AsRawFd::as_raw_fd); + + if let Some(fd) = fd { + let _ = self.registration.deregister(&mut SourceFd(&fd)); + } + + self.inner.take() + } + + /// Deregisters this file descriptor and returns ownership of the backing + /// object. + pub fn into_inner(mut self) -> T { + self.take_inner().unwrap() + } + + /// Polls for read readiness. + /// + /// If the file descriptor is not currently ready for reading, this method + /// will store a clone of the [`Waker`] from the provided [`Context`]. When the + /// file descriptor becomes ready for reading, [`Waker::wake`] will be called. + /// + /// Note that on multiple calls to [`poll_read_ready`] or + /// [`poll_read_ready_mut`], only the `Waker` from the `Context` passed to the + /// most recent call is scheduled to receive a wakeup. (However, + /// [`poll_write_ready`] retains a second, independent waker). + /// + /// This method is intended for cases where creating and pinning a future + /// via [`readable`] is not feasible. Where possible, using [`readable`] is + /// preferred, as this supports polling from multiple tasks at once. + /// + /// This method takes `&self`, so it is possible to call this method + /// concurrently with other methods on this struct. This method only + /// provides shared access to the inner IO resource when handling the + /// [`AsyncFdReadyGuard`]. + /// + /// [`poll_read_ready`]: method@Self::poll_read_ready + /// [`poll_read_ready_mut`]: method@Self::poll_read_ready_mut + /// [`poll_write_ready`]: method@Self::poll_write_ready + /// [`readable`]: method@Self::readable + /// [`Context`]: struct@std::task::Context + /// [`Waker`]: struct@std::task::Waker + /// [`Waker::wake`]: method@std::task::Waker::wake + pub fn poll_read_ready<'a>( + &'a self, + cx: &mut Context<'_>, + ) -> Poll<io::Result<AsyncFdReadyGuard<'a, T>>> { + let event = ready!(self.registration.poll_read_ready(cx))?; + + Ok(AsyncFdReadyGuard { + async_fd: self, + event: Some(event), + }) + .into() + } + + /// Polls for read readiness. + /// + /// If the file descriptor is not currently ready for reading, this method + /// will store a clone of the [`Waker`] from the provided [`Context`]. When the + /// file descriptor becomes ready for reading, [`Waker::wake`] will be called. + /// + /// Note that on multiple calls to [`poll_read_ready`] or + /// [`poll_read_ready_mut`], only the `Waker` from the `Context` passed to the + /// most recent call is scheduled to receive a wakeup. (However, + /// [`poll_write_ready`] retains a second, independent waker). + /// + /// This method is intended for cases where creating and pinning a future + /// via [`readable`] is not feasible. Where possible, using [`readable`] is + /// preferred, as this supports polling from multiple tasks at once. + /// + /// This method takes `&mut self`, so it is possible to access the inner IO + /// resource mutably when handling the [`AsyncFdReadyMutGuard`]. + /// + /// [`poll_read_ready`]: method@Self::poll_read_ready + /// [`poll_read_ready_mut`]: method@Self::poll_read_ready_mut + /// [`poll_write_ready`]: method@Self::poll_write_ready + /// [`readable`]: method@Self::readable + /// [`Context`]: struct@std::task::Context + /// [`Waker`]: struct@std::task::Waker + /// [`Waker::wake`]: method@std::task::Waker::wake + pub fn poll_read_ready_mut<'a>( + &'a mut self, + cx: &mut Context<'_>, + ) -> Poll<io::Result<AsyncFdReadyMutGuard<'a, T>>> { + let event = ready!(self.registration.poll_read_ready(cx))?; + + Ok(AsyncFdReadyMutGuard { + async_fd: self, + event: Some(event), + }) + .into() + } + + /// Polls for write readiness. + /// + /// If the file descriptor is not currently ready for writing, this method + /// will store a clone of the [`Waker`] from the provided [`Context`]. When the + /// file descriptor becomes ready for writing, [`Waker::wake`] will be called. + /// + /// Note that on multiple calls to [`poll_write_ready`] or + /// [`poll_write_ready_mut`], only the `Waker` from the `Context` passed to the + /// most recent call is scheduled to receive a wakeup. (However, + /// [`poll_read_ready`] retains a second, independent waker). + /// + /// This method is intended for cases where creating and pinning a future + /// via [`writable`] is not feasible. Where possible, using [`writable`] is + /// preferred, as this supports polling from multiple tasks at once. + /// + /// This method takes `&self`, so it is possible to call this method + /// concurrently with other methods on this struct. This method only + /// provides shared access to the inner IO resource when handling the + /// [`AsyncFdReadyGuard`]. + /// + /// [`poll_read_ready`]: method@Self::poll_read_ready + /// [`poll_write_ready`]: method@Self::poll_write_ready + /// [`poll_write_ready_mut`]: method@Self::poll_write_ready_mut + /// [`writable`]: method@Self::readable + /// [`Context`]: struct@std::task::Context + /// [`Waker`]: struct@std::task::Waker + /// [`Waker::wake`]: method@std::task::Waker::wake + pub fn poll_write_ready<'a>( + &'a self, + cx: &mut Context<'_>, + ) -> Poll<io::Result<AsyncFdReadyGuard<'a, T>>> { + let event = ready!(self.registration.poll_write_ready(cx))?; + + Ok(AsyncFdReadyGuard { + async_fd: self, + event: Some(event), + }) + .into() + } + + /// Polls for write readiness. + /// + /// If the file descriptor is not currently ready for writing, this method + /// will store a clone of the [`Waker`] from the provided [`Context`]. When the + /// file descriptor becomes ready for writing, [`Waker::wake`] will be called. + /// + /// Note that on multiple calls to [`poll_write_ready`] or + /// [`poll_write_ready_mut`], only the `Waker` from the `Context` passed to the + /// most recent call is scheduled to receive a wakeup. (However, + /// [`poll_read_ready`] retains a second, independent waker). + /// + /// This method is intended for cases where creating and pinning a future + /// via [`writable`] is not feasible. Where possible, using [`writable`] is + /// preferred, as this supports polling from multiple tasks at once. + /// + /// This method takes `&mut self`, so it is possible to access the inner IO + /// resource mutably when handling the [`AsyncFdReadyMutGuard`]. + /// + /// [`poll_read_ready`]: method@Self::poll_read_ready + /// [`poll_write_ready`]: method@Self::poll_write_ready + /// [`poll_write_ready_mut`]: method@Self::poll_write_ready_mut + /// [`writable`]: method@Self::readable + /// [`Context`]: struct@std::task::Context + /// [`Waker`]: struct@std::task::Waker + /// [`Waker::wake`]: method@std::task::Waker::wake + pub fn poll_write_ready_mut<'a>( + &'a mut self, + cx: &mut Context<'_>, + ) -> Poll<io::Result<AsyncFdReadyMutGuard<'a, T>>> { + let event = ready!(self.registration.poll_write_ready(cx))?; + + Ok(AsyncFdReadyMutGuard { + async_fd: self, + event: Some(event), + }) + .into() + } + + async fn readiness(&self, interest: Interest) -> io::Result<AsyncFdReadyGuard<'_, T>> { + let event = self.registration.readiness(interest).await?; + + Ok(AsyncFdReadyGuard { + async_fd: self, + event: Some(event), + }) + } + + async fn readiness_mut( + &mut self, + interest: Interest, + ) -> io::Result<AsyncFdReadyMutGuard<'_, T>> { + let event = self.registration.readiness(interest).await?; + + Ok(AsyncFdReadyMutGuard { + async_fd: self, + event: Some(event), + }) + } + + /// Waits for the file descriptor to become readable, returning a + /// [`AsyncFdReadyGuard`] that must be dropped to resume read-readiness + /// polling. + /// + /// This method takes `&self`, so it is possible to call this method + /// concurrently with other methods on this struct. This method only + /// provides shared access to the inner IO resource when handling the + /// [`AsyncFdReadyGuard`]. + #[allow(clippy::needless_lifetimes)] // The lifetime improves rustdoc rendering. + pub async fn readable<'a>(&'a self) -> io::Result<AsyncFdReadyGuard<'a, T>> { + self.readiness(Interest::READABLE).await + } + + /// Waits for the file descriptor to become readable, returning a + /// [`AsyncFdReadyMutGuard`] that must be dropped to resume read-readiness + /// polling. + /// + /// This method takes `&mut self`, so it is possible to access the inner IO + /// resource mutably when handling the [`AsyncFdReadyMutGuard`]. + #[allow(clippy::needless_lifetimes)] // The lifetime improves rustdoc rendering. + pub async fn readable_mut<'a>(&'a mut self) -> io::Result<AsyncFdReadyMutGuard<'a, T>> { + self.readiness_mut(Interest::READABLE).await + } + + /// Waits for the file descriptor to become writable, returning a + /// [`AsyncFdReadyGuard`] that must be dropped to resume write-readiness + /// polling. + /// + /// This method takes `&self`, so it is possible to call this method + /// concurrently with other methods on this struct. This method only + /// provides shared access to the inner IO resource when handling the + /// [`AsyncFdReadyGuard`]. + #[allow(clippy::needless_lifetimes)] // The lifetime improves rustdoc rendering. + pub async fn writable<'a>(&'a self) -> io::Result<AsyncFdReadyGuard<'a, T>> { + self.readiness(Interest::WRITABLE).await + } + + /// Waits for the file descriptor to become writable, returning a + /// [`AsyncFdReadyMutGuard`] that must be dropped to resume write-readiness + /// polling. + /// + /// This method takes `&mut self`, so it is possible to access the inner IO + /// resource mutably when handling the [`AsyncFdReadyMutGuard`]. + #[allow(clippy::needless_lifetimes)] // The lifetime improves rustdoc rendering. + pub async fn writable_mut<'a>(&'a mut self) -> io::Result<AsyncFdReadyMutGuard<'a, T>> { + self.readiness_mut(Interest::WRITABLE).await + } +} + +impl<T: AsRawFd> AsRawFd for AsyncFd<T> { + fn as_raw_fd(&self) -> RawFd { + self.inner.as_ref().unwrap().as_raw_fd() + } +} + +impl<T: std::fmt::Debug + AsRawFd> std::fmt::Debug for AsyncFd<T> { + fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result { + f.debug_struct("AsyncFd") + .field("inner", &self.inner) + .finish() + } +} + +impl<T: AsRawFd> Drop for AsyncFd<T> { + fn drop(&mut self) { + let _ = self.take_inner(); + } +} + +impl<'a, Inner: AsRawFd> AsyncFdReadyGuard<'a, Inner> { + /// Indicates to tokio that the file descriptor is no longer ready. The + /// internal readiness flag will be cleared, and tokio will wait for the + /// next edge-triggered readiness notification from the OS. + /// + /// It is critical that this function not be called unless your code + /// _actually observes_ that the file descriptor is _not_ ready. Do not call + /// it simply because, for example, a read succeeded; it should be called + /// when a read is observed to block. + /// + /// [`drop`]: method@std::mem::drop + pub fn clear_ready(&mut self) { + if let Some(event) = self.event.take() { + self.async_fd.registration.clear_readiness(event); + } + } + + /// This method should be invoked when you intentionally want to keep the + /// ready flag asserted. + /// + /// While this function is itself a no-op, it satisfies the `#[must_use]` + /// constraint on the [`AsyncFdReadyGuard`] type. + pub fn retain_ready(&mut self) { + // no-op + } + + /// Performs the provided IO operation. + /// + /// If `f` returns a [`WouldBlock`] error, the readiness state associated + /// with this file descriptor is cleared, and the method returns + /// `Err(TryIoError::WouldBlock)`. You will typically need to poll the + /// `AsyncFd` again when this happens. + /// + /// This method helps ensure that the readiness state of the underlying file + /// descriptor remains in sync with the tokio-side readiness state, by + /// clearing the tokio-side state only when a [`WouldBlock`] condition + /// occurs. It is the responsibility of the caller to ensure that `f` + /// returns [`WouldBlock`] only if the file descriptor that originated this + /// `AsyncFdReadyGuard` no longer expresses the readiness state that was queried to + /// create this `AsyncFdReadyGuard`. + /// + /// [`WouldBlock`]: std::io::ErrorKind::WouldBlock + // Alias for old name in 0.x + #[cfg_attr(docsrs, doc(alias = "with_io"))] + pub fn try_io<R>( + &mut self, + f: impl FnOnce(&'a AsyncFd<Inner>) -> io::Result<R>, + ) -> Result<io::Result<R>, TryIoError> { + let result = f(self.async_fd); + + if let Err(e) = result.as_ref() { + if e.kind() == io::ErrorKind::WouldBlock { + self.clear_ready(); + } + } + + match result { + Err(err) if err.kind() == io::ErrorKind::WouldBlock => Err(TryIoError(())), + result => Ok(result), + } + } + + /// Returns a shared reference to the inner [`AsyncFd`]. + pub fn get_ref(&self) -> &'a AsyncFd<Inner> { + self.async_fd + } + + /// Returns a shared reference to the backing object of the inner [`AsyncFd`]. + pub fn get_inner(&self) -> &'a Inner { + self.get_ref().get_ref() + } +} + +impl<'a, Inner: AsRawFd> AsyncFdReadyMutGuard<'a, Inner> { + /// Indicates to tokio that the file descriptor is no longer ready. The + /// internal readiness flag will be cleared, and tokio will wait for the + /// next edge-triggered readiness notification from the OS. + /// + /// It is critical that this function not be called unless your code + /// _actually observes_ that the file descriptor is _not_ ready. Do not call + /// it simply because, for example, a read succeeded; it should be called + /// when a read is observed to block. + /// + /// [`drop`]: method@std::mem::drop + pub fn clear_ready(&mut self) { + if let Some(event) = self.event.take() { + self.async_fd.registration.clear_readiness(event); + } + } + + /// This method should be invoked when you intentionally want to keep the + /// ready flag asserted. + /// + /// While this function is itself a no-op, it satisfies the `#[must_use]` + /// constraint on the [`AsyncFdReadyGuard`] type. + pub fn retain_ready(&mut self) { + // no-op + } + + /// Performs the provided IO operation. + /// + /// If `f` returns a [`WouldBlock`] error, the readiness state associated + /// with this file descriptor is cleared, and the method returns + /// `Err(TryIoError::WouldBlock)`. You will typically need to poll the + /// `AsyncFd` again when this happens. + /// + /// This method helps ensure that the readiness state of the underlying file + /// descriptor remains in sync with the tokio-side readiness state, by + /// clearing the tokio-side state only when a [`WouldBlock`] condition + /// occurs. It is the responsibility of the caller to ensure that `f` + /// returns [`WouldBlock`] only if the file descriptor that originated this + /// `AsyncFdReadyGuard` no longer expresses the readiness state that was queried to + /// create this `AsyncFdReadyGuard`. + /// + /// [`WouldBlock`]: std::io::ErrorKind::WouldBlock + pub fn try_io<R>( + &mut self, + f: impl FnOnce(&mut AsyncFd<Inner>) -> io::Result<R>, + ) -> Result<io::Result<R>, TryIoError> { + let result = f(self.async_fd); + + if let Err(e) = result.as_ref() { + if e.kind() == io::ErrorKind::WouldBlock { + self.clear_ready(); + } + } + + match result { + Err(err) if err.kind() == io::ErrorKind::WouldBlock => Err(TryIoError(())), + result => Ok(result), + } + } + + /// Returns a shared reference to the inner [`AsyncFd`]. + pub fn get_ref(&self) -> &AsyncFd<Inner> { + self.async_fd + } + + /// Returns a mutable reference to the inner [`AsyncFd`]. + pub fn get_mut(&mut self) -> &mut AsyncFd<Inner> { + self.async_fd + } + + /// Returns a shared reference to the backing object of the inner [`AsyncFd`]. + pub fn get_inner(&self) -> &Inner { + self.get_ref().get_ref() + } + + /// Returns a mutable reference to the backing object of the inner [`AsyncFd`]. + pub fn get_inner_mut(&mut self) -> &mut Inner { + self.get_mut().get_mut() + } +} + +impl<'a, T: std::fmt::Debug + AsRawFd> std::fmt::Debug for AsyncFdReadyGuard<'a, T> { + fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result { + f.debug_struct("ReadyGuard") + .field("async_fd", &self.async_fd) + .finish() + } +} + +impl<'a, T: std::fmt::Debug + AsRawFd> std::fmt::Debug for AsyncFdReadyMutGuard<'a, T> { + fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result { + f.debug_struct("MutReadyGuard") + .field("async_fd", &self.async_fd) + .finish() + } +} + +/// The error type returned by [`try_io`]. +/// +/// This error indicates that the IO resource returned a [`WouldBlock`] error. +/// +/// [`WouldBlock`]: std::io::ErrorKind::WouldBlock +/// [`try_io`]: method@AsyncFdReadyGuard::try_io +#[derive(Debug)] +pub struct TryIoError(()); |