| use crate::{event, sys, Events, Interest, Token}; |
| use log::trace; |
| #[cfg(unix)] |
| use std::os::unix::io::{AsRawFd, RawFd}; |
| use std::time::Duration; |
| use std::{fmt, io}; |
| |
| /// Polls for readiness events on all registered values. |
| /// |
| /// `Poll` allows a program to monitor a large number of [`event::Source`]s, |
| /// waiting until one or more become "ready" for some class of operations; e.g. |
| /// reading and writing. An event source is considered ready if it is possible |
| /// to immediately perform a corresponding operation; e.g. [`read`] or |
| /// [`write`]. |
| /// |
| /// To use `Poll`, an `event::Source` must first be registered with the `Poll` |
| /// instance using the [`register`] method on its associated `Register`, |
| /// supplying readiness interest. The readiness interest tells `Poll` which |
| /// specific operations on the handle to monitor for readiness. A `Token` is |
| /// also passed to the [`register`] function. When `Poll` returns a readiness |
| /// event, it will include this token. This associates the event with the |
| /// event source that generated the event. |
| /// |
| /// [`event::Source`]: ./event/trait.Source.html |
| /// [`read`]: ./net/struct.TcpStream.html#method.read |
| /// [`write`]: ./net/struct.TcpStream.html#method.write |
| /// [`register`]: struct.Registry.html#method.register |
| /// |
| /// # Examples |
| /// |
| /// A basic example -- establishing a `TcpStream` connection. |
| /// |
| #[cfg_attr(all(feature = "os-poll", feature = "net"), doc = "```")] |
| #[cfg_attr(not(all(feature = "os-poll", feature = "net")), doc = "```ignore")] |
| /// # use std::error::Error; |
| /// # fn main() -> Result<(), Box<dyn Error>> { |
| /// use mio::{Events, Poll, Interest, Token}; |
| /// use mio::net::TcpStream; |
| /// |
| /// use std::net::{self, SocketAddr}; |
| /// |
| /// // Bind a server socket to connect to. |
| /// let addr: SocketAddr = "127.0.0.1:0".parse()?; |
| /// let server = net::TcpListener::bind(addr)?; |
| /// |
| /// // Construct a new `Poll` handle as well as the `Events` we'll store into |
| /// let mut poll = Poll::new()?; |
| /// let mut events = Events::with_capacity(1024); |
| /// |
| /// // Connect the stream |
| /// let mut stream = TcpStream::connect(server.local_addr()?)?; |
| /// |
| /// // Register the stream with `Poll` |
| /// poll.registry().register(&mut stream, Token(0), Interest::READABLE | Interest::WRITABLE)?; |
| /// |
| /// // Wait for the socket to become ready. This has to happens in a loop to |
| /// // handle spurious wakeups. |
| /// loop { |
| /// poll.poll(&mut events, None)?; |
| /// |
| /// for event in &events { |
| /// if event.token() == Token(0) && event.is_writable() { |
| /// // The socket connected (probably, it could still be a spurious |
| /// // wakeup) |
| /// return Ok(()); |
| /// } |
| /// } |
| /// } |
| /// # } |
| /// ``` |
| /// |
| /// # Portability |
| /// |
| /// Using `Poll` provides a portable interface across supported platforms as |
| /// long as the caller takes the following into consideration: |
| /// |
| /// ### Spurious events |
| /// |
| /// [`Poll::poll`] may return readiness events even if the associated |
| /// event source is not actually ready. Given the same code, this may |
| /// happen more on some platforms than others. It is important to never assume |
| /// that, just because a readiness event was received, that the associated |
| /// operation will succeed as well. |
| /// |
| /// If operation fails with [`WouldBlock`], then the caller should not treat |
| /// this as an error, but instead should wait until another readiness event is |
| /// received. |
| /// |
| /// ### Draining readiness |
| /// |
| /// Once a readiness event is received, the corresponding operation must be |
| /// performed repeatedly until it returns [`WouldBlock`]. Unless this is done, |
| /// there is no guarantee that another readiness event will be delivered, even |
| /// if further data is received for the event source. |
| /// |
| /// [`WouldBlock`]: std::io::ErrorKind::WouldBlock |
| /// |
| /// ### Readiness operations |
| /// |
| /// The only readiness operations that are guaranteed to be present on all |
| /// supported platforms are [`readable`] and [`writable`]. All other readiness |
| /// operations may have false negatives and as such should be considered |
| /// **hints**. This means that if a socket is registered with [`readable`] |
| /// interest and either an error or close is received, a readiness event will |
| /// be generated for the socket, but it **may** only include `readable` |
| /// readiness. Also note that, given the potential for spurious events, |
| /// receiving a readiness event with `read_closed`, `write_closed`, or `error` |
| /// doesn't actually mean that a `read` on the socket will return a result |
| /// matching the readiness event. |
| /// |
| /// In other words, portable programs that explicitly check for [`read_closed`], |
| /// [`write_closed`], or [`error`] readiness should be doing so as an |
| /// **optimization** and always be able to handle an error or close situation |
| /// when performing the actual read operation. |
| /// |
| /// [`readable`]: ./event/struct.Event.html#method.is_readable |
| /// [`writable`]: ./event/struct.Event.html#method.is_writable |
| /// [`error`]: ./event/struct.Event.html#method.is_error |
| /// [`read_closed`]: ./event/struct.Event.html#method.is_read_closed |
| /// [`write_closed`]: ./event/struct.Event.html#method.is_write_closed |
| /// |
| /// ### Registering handles |
| /// |
| /// Unless otherwise noted, it should be assumed that types implementing |
| /// [`event::Source`] will never become ready unless they are registered with |
| /// `Poll`. |
| /// |
| /// For example: |
| /// |
| #[cfg_attr(all(feature = "os-poll", feature = "net"), doc = "```")] |
| #[cfg_attr(not(all(feature = "os-poll", feature = "net")), doc = "```ignore")] |
| /// # use std::error::Error; |
| /// # use std::net; |
| /// # fn main() -> Result<(), Box<dyn Error>> { |
| /// use mio::{Poll, Interest, Token}; |
| /// use mio::net::TcpStream; |
| /// use std::net::SocketAddr; |
| /// use std::time::Duration; |
| /// use std::thread; |
| /// |
| /// let address: SocketAddr = "127.0.0.1:0".parse()?; |
| /// let listener = net::TcpListener::bind(address)?; |
| /// let mut sock = TcpStream::connect(listener.local_addr()?)?; |
| /// |
| /// thread::sleep(Duration::from_secs(1)); |
| /// |
| /// let poll = Poll::new()?; |
| /// |
| /// // The connect is not guaranteed to have started until it is registered at |
| /// // this point |
| /// poll.registry().register(&mut sock, Token(0), Interest::READABLE | Interest::WRITABLE)?; |
| /// # Ok(()) |
| /// # } |
| /// ``` |
| /// |
| /// ### Dropping `Poll` |
| /// |
| /// When the `Poll` instance is dropped it may cancel in-flight operations for |
| /// the registered [event sources], meaning that no further events for them may |
| /// be received. It also means operations on the registered event sources may no |
| /// longer work. It is up to the user to keep the `Poll` instance alive while |
| /// registered event sources are being used. |
| /// |
| /// [event sources]: ./event/trait.Source.html |
| /// |
| /// # Implementation notes |
| /// |
| /// `Poll` is backed by the selector provided by the operating system. |
| /// |
| /// | OS | Selector | |
| /// |---------------|-----------| |
| /// | Android | [epoll] | |
| /// | DragonFly BSD | [kqueue] | |
| /// | FreeBSD | [kqueue] | |
| /// | Linux | [epoll] | |
| /// | NetBSD | [kqueue] | |
| /// | OpenBSD | [kqueue] | |
| /// | Solaris | [epoll] | |
| /// | illumos | [epoll] | |
| /// | Windows | [IOCP] | |
| /// | iOS | [kqueue] | |
| /// | macOS | [kqueue] | |
| /// |
| /// On all supported platforms, socket operations are handled by using the |
| /// system selector. Platform specific extensions (e.g. [`SourceFd`]) allow |
| /// accessing other features provided by individual system selectors. For |
| /// example, Linux's [`signalfd`] feature can be used by registering the FD with |
| /// `Poll` via [`SourceFd`]. |
| /// |
| /// On all platforms except windows, a call to [`Poll::poll`] is mostly just a |
| /// direct call to the system selector. However, [IOCP] uses a completion model |
| /// instead of a readiness model. In this case, `Poll` must adapt the completion |
| /// model Mio's API. While non-trivial, the bridge layer is still quite |
| /// efficient. The most expensive part being calls to `read` and `write` require |
| /// data to be copied into an intermediate buffer before it is passed to the |
| /// kernel. |
| /// |
| /// [epoll]: http://man7.org/linux/man-pages/man7/epoll.7.html |
| /// [kqueue]: https://www.freebsd.org/cgi/man.cgi?query=kqueue&sektion=2 |
| /// [IOCP]: https://msdn.microsoft.com/en-us/library/windows/desktop/aa365198(v=vs.85).aspx |
| /// [`signalfd`]: http://man7.org/linux/man-pages/man2/signalfd.2.html |
| /// [`SourceFd`]: unix/struct.SourceFd.html |
| /// [`Poll::poll`]: struct.Poll.html#method.poll |
| pub struct Poll { |
| registry: Registry, |
| } |
| |
| /// Registers I/O resources. |
| pub struct Registry { |
| selector: sys::Selector, |
| } |
| |
| impl Poll { |
| /// Create a separate `Registry` which can be used to register |
| /// `event::Source`s. |
| pub fn registry(&self) -> &Registry { |
| &self.registry |
| } |
| |
| /// Wait for readiness events |
| /// |
| /// Blocks the current thread and waits for readiness events for any of the |
| /// [`event::Source`]s that have been registered with this `Poll` instance. |
| /// The function will block until either at least one readiness event has |
| /// been received or `timeout` has elapsed. A `timeout` of `None` means that |
| /// `poll` will block until a readiness event has been received. |
| /// |
| /// The supplied `events` will be cleared and newly received readiness events |
| /// will be pushed onto the end. At most `events.capacity()` events will be |
| /// returned. If there are further pending readiness events, they will be |
| /// returned on the next call to `poll`. |
| /// |
| /// A single call to `poll` may result in multiple readiness events being |
| /// returned for a single event source. For example, if a TCP socket becomes |
| /// both readable and writable, it may be possible for a single readiness |
| /// event to be returned with both [`readable`] and [`writable`] readiness |
| /// **OR** two separate events may be returned, one with [`readable`] set |
| /// and one with [`writable`] set. |
| /// |
| /// Note that the `timeout` will be rounded up to the system clock |
| /// granularity (usually 1ms), and kernel scheduling delays mean that |
| /// the blocking interval may be overrun by a small amount. |
| /// |
| /// See the [struct] level documentation for a higher level discussion of |
| /// polling. |
| /// |
| /// [`event::Source`]: ./event/trait.Source.html |
| /// [`readable`]: struct.Interest.html#associatedconstant.READABLE |
| /// [`writable`]: struct.Interest.html#associatedconstant.WRITABLE |
| /// [struct]: struct.Poll.html |
| /// [`iter`]: ./event/struct.Events.html#method.iter |
| /// |
| /// # Notes |
| /// |
| /// This returns any errors without attempting to retry, previous versions |
| /// of Mio would automatically retry the poll call if it was interrupted |
| /// (if `EINTR` was returned). |
| /// |
| /// # Examples |
| /// |
| /// A basic example -- establishing a `TcpStream` connection. |
| /// |
| #[cfg_attr(all(feature = "os-poll", feature = "net"), doc = "```")] |
| #[cfg_attr(not(all(feature = "os-poll", feature = "net")), doc = "```ignore")] |
| /// # use std::error::Error; |
| /// # fn main() -> Result<(), Box<dyn Error>> { |
| /// use mio::{Events, Poll, Interest, Token}; |
| /// use mio::net::TcpStream; |
| /// |
| /// use std::net::{TcpListener, SocketAddr}; |
| /// use std::thread; |
| /// |
| /// // Bind a server socket to connect to. |
| /// let addr: SocketAddr = "127.0.0.1:0".parse()?; |
| /// let server = TcpListener::bind(addr)?; |
| /// let addr = server.local_addr()?.clone(); |
| /// |
| /// // Spawn a thread to accept the socket |
| /// thread::spawn(move || { |
| /// let _ = server.accept(); |
| /// }); |
| /// |
| /// // Construct a new `Poll` handle as well as the `Events` we'll store into |
| /// let mut poll = Poll::new()?; |
| /// let mut events = Events::with_capacity(1024); |
| /// |
| /// // Connect the stream |
| /// let mut stream = TcpStream::connect(addr)?; |
| /// |
| /// // Register the stream with `Poll` |
| /// poll.registry().register( |
| /// &mut stream, |
| /// Token(0), |
| /// Interest::READABLE | Interest::WRITABLE)?; |
| /// |
| /// // Wait for the socket to become ready. This has to happens in a loop to |
| /// // handle spurious wakeups. |
| /// loop { |
| /// poll.poll(&mut events, None)?; |
| /// |
| /// for event in &events { |
| /// if event.token() == Token(0) && event.is_writable() { |
| /// // The socket connected (probably, it could still be a spurious |
| /// // wakeup) |
| /// return Ok(()); |
| /// } |
| /// } |
| /// } |
| /// # } |
| /// ``` |
| /// |
| /// [struct]: # |
| pub fn poll(&mut self, events: &mut Events, timeout: Option<Duration>) -> io::Result<()> { |
| self.registry.selector.select(events.sys(), timeout) |
| } |
| } |
| |
| cfg_os_poll! { |
| impl Poll { |
| /// Return a new `Poll` handle. |
| /// |
| /// This function will make a syscall to the operating system to create |
| /// the system selector. If this syscall fails, `Poll::new` will return |
| /// with the error. |
| /// |
| /// See [struct] level docs for more details. |
| /// |
| /// [struct]: struct.Poll.html |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// # use std::error::Error; |
| /// # fn main() -> Result<(), Box<dyn Error>> { |
| /// use mio::{Poll, Events}; |
| /// use std::time::Duration; |
| /// |
| /// let mut poll = match Poll::new() { |
| /// Ok(poll) => poll, |
| /// Err(e) => panic!("failed to create Poll instance; err={:?}", e), |
| /// }; |
| /// |
| /// // Create a structure to receive polled events |
| /// let mut events = Events::with_capacity(1024); |
| /// |
| /// // Wait for events, but none will be received because no |
| /// // `event::Source`s have been registered with this `Poll` instance. |
| /// poll.poll(&mut events, Some(Duration::from_millis(500)))?; |
| /// assert!(events.is_empty()); |
| /// # Ok(()) |
| /// # } |
| /// ``` |
| pub fn new() -> io::Result<Poll> { |
| sys::Selector::new().map(|selector| Poll { |
| registry: Registry { selector }, |
| }) |
| } |
| } |
| } |
| |
| #[cfg(unix)] |
| impl AsRawFd for Poll { |
| fn as_raw_fd(&self) -> RawFd { |
| self.registry.as_raw_fd() |
| } |
| } |
| |
| impl fmt::Debug for Poll { |
| fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result { |
| fmt.debug_struct("Poll").finish() |
| } |
| } |
| |
| impl Registry { |
| /// Register an [`event::Source`] with the `Poll` instance. |
| /// |
| /// Once registered, the `Poll` instance will monitor the event source for |
| /// readiness state changes. When it notices a state change, it will return |
| /// a readiness event for the handle the next time [`poll`] is called. |
| /// |
| /// See [`Poll`] docs for a high level overview. |
| /// |
| /// # Arguments |
| /// |
| /// `source: &S: event::Source`: This is the source of events that the |
| /// `Poll` instance should monitor for readiness state changes. |
| /// |
| /// `token: Token`: The caller picks a token to associate with the socket. |
| /// When [`poll`] returns an event for the handle, this token is included. |
| /// This allows the caller to map the event to its source. The token |
| /// associated with the `event::Source` can be changed at any time by |
| /// calling [`reregister`]. |
| /// |
| /// See documentation on [`Token`] for an example showing how to pick |
| /// [`Token`] values. |
| /// |
| /// `interest: Interest`: Specifies which operations `Poll` should monitor |
| /// for readiness. `Poll` will only return readiness events for operations |
| /// specified by this argument. |
| /// |
| /// If a socket is registered with readable interest and the socket becomes |
| /// writable, no event will be returned from [`poll`]. |
| /// |
| /// The readiness interest for an `event::Source` can be changed at any time |
| /// by calling [`reregister`]. |
| /// |
| /// # Notes |
| /// |
| /// Callers must ensure that if a source being registered with a `Poll` |
| /// instance was previously registered with that `Poll` instance, then a |
| /// call to [`deregister`] has already occurred. Consecutive calls to |
| /// `register` is unspecified behavior. |
| /// |
| /// Unless otherwise specified, the caller should assume that once an event |
| /// source is registered with a `Poll` instance, it is bound to that `Poll` |
| /// instance for the lifetime of the event source. This remains true even |
| /// if the event source is deregistered from the poll instance using |
| /// [`deregister`]. |
| /// |
| /// [`event::Source`]: ./event/trait.Source.html |
| /// [`poll`]: struct.Poll.html#method.poll |
| /// [`reregister`]: struct.Registry.html#method.reregister |
| /// [`deregister`]: struct.Registry.html#method.deregister |
| /// [`Token`]: struct.Token.html |
| /// |
| /// # Examples |
| /// |
| #[cfg_attr(all(feature = "os-poll", feature = "net"), doc = "```")] |
| #[cfg_attr(not(all(feature = "os-poll", feature = "net")), doc = "```ignore")] |
| /// # use std::error::Error; |
| /// # use std::net; |
| /// # fn main() -> Result<(), Box<dyn Error>> { |
| /// use mio::{Events, Poll, Interest, Token}; |
| /// use mio::net::TcpStream; |
| /// use std::net::SocketAddr; |
| /// use std::time::{Duration, Instant}; |
| /// |
| /// let mut poll = Poll::new()?; |
| /// |
| /// let address: SocketAddr = "127.0.0.1:0".parse()?; |
| /// let listener = net::TcpListener::bind(address)?; |
| /// let mut socket = TcpStream::connect(listener.local_addr()?)?; |
| /// |
| /// // Register the socket with `poll` |
| /// poll.registry().register( |
| /// &mut socket, |
| /// Token(0), |
| /// Interest::READABLE | Interest::WRITABLE)?; |
| /// |
| /// let mut events = Events::with_capacity(1024); |
| /// let start = Instant::now(); |
| /// let timeout = Duration::from_millis(500); |
| /// |
| /// loop { |
| /// let elapsed = start.elapsed(); |
| /// |
| /// if elapsed >= timeout { |
| /// // Connection timed out |
| /// return Ok(()); |
| /// } |
| /// |
| /// let remaining = timeout - elapsed; |
| /// poll.poll(&mut events, Some(remaining))?; |
| /// |
| /// for event in &events { |
| /// if event.token() == Token(0) { |
| /// // Something (probably) happened on the socket. |
| /// return Ok(()); |
| /// } |
| /// } |
| /// } |
| /// # } |
| /// ``` |
| pub fn register<S>(&self, source: &mut S, token: Token, interests: Interest) -> io::Result<()> |
| where |
| S: event::Source + ?Sized, |
| { |
| trace!( |
| "registering event source with poller: token={:?}, interests={:?}", |
| token, |
| interests |
| ); |
| source.register(self, token, interests) |
| } |
| |
| /// Re-register an [`event::Source`] with the `Poll` instance. |
| /// |
| /// Re-registering an event source allows changing the details of the |
| /// registration. Specifically, it allows updating the associated `token` |
| /// and `interests` specified in previous `register` and `reregister` calls. |
| /// |
| /// The `reregister` arguments fully override the previous values. In other |
| /// words, if a socket is registered with [`readable`] interest and the call |
| /// to `reregister` specifies [`writable`], then read interest is no longer |
| /// requested for the handle. |
| /// |
| /// The event source must have previously been registered with this instance |
| /// of `Poll`, otherwise the behavior is unspecified. |
| /// |
| /// See the [`register`] documentation for details about the function |
| /// arguments and see the [`struct`] docs for a high level overview of |
| /// polling. |
| /// |
| /// # Examples |
| /// |
| #[cfg_attr(all(feature = "os-poll", feature = "net"), doc = "```")] |
| #[cfg_attr(not(all(feature = "os-poll", feature = "net")), doc = "```ignore")] |
| /// # use std::error::Error; |
| /// # use std::net; |
| /// # fn main() -> Result<(), Box<dyn Error>> { |
| /// use mio::{Poll, Interest, Token}; |
| /// use mio::net::TcpStream; |
| /// use std::net::SocketAddr; |
| /// |
| /// let poll = Poll::new()?; |
| /// |
| /// let address: SocketAddr = "127.0.0.1:0".parse()?; |
| /// let listener = net::TcpListener::bind(address)?; |
| /// let mut socket = TcpStream::connect(listener.local_addr()?)?; |
| /// |
| /// // Register the socket with `poll`, requesting readable |
| /// poll.registry().register( |
| /// &mut socket, |
| /// Token(0), |
| /// Interest::READABLE)?; |
| /// |
| /// // Reregister the socket specifying write interest instead. Even though |
| /// // the token is the same it must be specified. |
| /// poll.registry().reregister( |
| /// &mut socket, |
| /// Token(0), |
| /// Interest::WRITABLE)?; |
| /// # Ok(()) |
| /// # } |
| /// ``` |
| /// |
| /// [`event::Source`]: ./event/trait.Source.html |
| /// [`struct`]: struct.Poll.html |
| /// [`register`]: struct.Registry.html#method.register |
| /// [`readable`]: ./event/struct.Event.html#is_readable |
| /// [`writable`]: ./event/struct.Event.html#is_writable |
| pub fn reregister<S>(&self, source: &mut S, token: Token, interests: Interest) -> io::Result<()> |
| where |
| S: event::Source + ?Sized, |
| { |
| trace!( |
| "reregistering event source with poller: token={:?}, interests={:?}", |
| token, |
| interests |
| ); |
| source.reregister(self, token, interests) |
| } |
| |
| /// Deregister an [`event::Source`] with the `Poll` instance. |
| /// |
| /// When an event source is deregistered, the `Poll` instance will no longer |
| /// monitor it for readiness state changes. Deregistering clears up any |
| /// internal resources needed to track the handle. After an explicit call |
| /// to this method completes, it is guaranteed that the token previously |
| /// registered to this handle will not be returned by a future poll, so long |
| /// as a happens-before relationship is established between this call and |
| /// the poll. |
| /// |
| /// The event source must have previously been registered with this instance |
| /// of `Poll`, otherwise the behavior is unspecified. |
| /// |
| /// A handle can be passed back to `register` after it has been |
| /// deregistered; however, it must be passed back to the **same** `Poll` |
| /// instance, otherwise the behavior is unspecified. |
| /// |
| /// # Examples |
| /// |
| #[cfg_attr(all(feature = "os-poll", feature = "net"), doc = "```")] |
| #[cfg_attr(not(all(feature = "os-poll", feature = "net")), doc = "```ignore")] |
| /// # use std::error::Error; |
| /// # use std::net; |
| /// # fn main() -> Result<(), Box<dyn Error>> { |
| /// use mio::{Events, Poll, Interest, Token}; |
| /// use mio::net::TcpStream; |
| /// use std::net::SocketAddr; |
| /// use std::time::Duration; |
| /// |
| /// let mut poll = Poll::new()?; |
| /// |
| /// let address: SocketAddr = "127.0.0.1:0".parse()?; |
| /// let listener = net::TcpListener::bind(address)?; |
| /// let mut socket = TcpStream::connect(listener.local_addr()?)?; |
| /// |
| /// // Register the socket with `poll` |
| /// poll.registry().register( |
| /// &mut socket, |
| /// Token(0), |
| /// Interest::READABLE)?; |
| /// |
| /// poll.registry().deregister(&mut socket)?; |
| /// |
| /// let mut events = Events::with_capacity(1024); |
| /// |
| /// // Set a timeout because this poll should never receive any events. |
| /// poll.poll(&mut events, Some(Duration::from_secs(1)))?; |
| /// assert!(events.is_empty()); |
| /// # Ok(()) |
| /// # } |
| /// ``` |
| pub fn deregister<S>(&self, source: &mut S) -> io::Result<()> |
| where |
| S: event::Source + ?Sized, |
| { |
| trace!("deregistering event source from poller"); |
| source.deregister(self) |
| } |
| |
| /// Creates a new independently owned `Registry`. |
| /// |
| /// Event sources registered with this `Registry` will be registered with |
| /// the original `Registry` and `Poll` instance. |
| pub fn try_clone(&self) -> io::Result<Registry> { |
| self.selector |
| .try_clone() |
| .map(|selector| Registry { selector }) |
| } |
| |
| /// Internal check to ensure only a single `Waker` is active per [`Poll`] |
| /// instance. |
| #[cfg(debug_assertions)] |
| pub(crate) fn register_waker(&self) { |
| if self.selector.register_waker() { |
| panic!("Only a single `Waker` can be active per `Poll` instance"); |
| } |
| } |
| } |
| |
| impl fmt::Debug for Registry { |
| fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result { |
| fmt.debug_struct("Registry").finish() |
| } |
| } |
| |
| #[cfg(unix)] |
| impl AsRawFd for Registry { |
| fn as_raw_fd(&self) -> RawFd { |
| self.selector.as_raw_fd() |
| } |
| } |
| |
| /// Get access to the `sys::Selector` from `Registry`. |
| pub(crate) fn selector(registry: &Registry) -> &sys::Selector { |
| ®istry.selector |
| } |
| |
| cfg_os_poll! { |
| #[cfg(unix)] |
| #[test] |
| pub fn as_raw_fd() { |
| let poll = Poll::new().unwrap(); |
| assert!(poll.as_raw_fd() > 0); |
| } |
| } |