| use crate::{sys, Token}; |
| |
| use std::fmt; |
| |
| /// A readiness event. |
| /// |
| /// `Event` is a readiness state paired with a [`Token`]. It is returned by |
| /// [`Poll::poll`]. |
| /// |
| /// For more documentation on polling and events, see [`Poll`]. |
| /// |
| /// [`Poll::poll`]: ../struct.Poll.html#method.poll |
| /// [`Poll`]: ../struct.Poll.html |
| /// [`Token`]: ../struct.Token.html |
| #[derive(Clone)] |
| #[repr(transparent)] |
| pub struct Event { |
| inner: sys::Event, |
| } |
| |
| impl Event { |
| /// Returns the event's token. |
| pub fn token(&self) -> Token { |
| sys::event::token(&self.inner) |
| } |
| |
| /// Returns true if the event contains readable readiness. |
| /// |
| /// # Notes |
| /// |
| /// Out-of-band (OOB) data also triggers readable events. But most |
| /// applications don't actually read OOB data, this could leave an |
| /// application open to a Denial-of-Service (Dos) attack, see |
| /// <https://github.com/sandstorm-io/sandstorm-website/blob/58f93346028c0576e8147627667328eaaf4be9fa/_posts/2015-04-08-osx-security-bug.md>. |
| /// However because Mio uses edge-triggers it will not result in an infinite |
| /// loop as described in the article above. |
| pub fn is_readable(&self) -> bool { |
| sys::event::is_readable(&self.inner) |
| } |
| |
| /// Returns true if the event contains writable readiness. |
| pub fn is_writable(&self) -> bool { |
| sys::event::is_writable(&self.inner) |
| } |
| |
| /// Returns true if the event contains error readiness. |
| /// |
| /// Error events occur when the socket enters an error state. In this case, |
| /// the socket will also receive a readable or writable event. Reading or |
| /// writing to the socket will result in an error. |
| /// |
| /// # Notes |
| /// |
| /// Method is available on all platforms, but not all platforms trigger the |
| /// error event. |
| /// |
| /// The table below shows what flags are checked on what OS. |
| /// |
| /// | [OS selector] | Flag(s) checked | |
| /// |---------------|-----------------| |
| /// | [epoll] | `EPOLLERR` | |
| /// | [kqueue] | `EV_ERROR` and `EV_EOF` with `fflags` set to `0`. | |
| /// |
| /// [OS selector]: ../struct.Poll.html#implementation-notes |
| /// [epoll]: https://man7.org/linux/man-pages/man7/epoll.7.html |
| /// [kqueue]: https://www.freebsd.org/cgi/man.cgi?query=kqueue&sektion=2 |
| pub fn is_error(&self) -> bool { |
| sys::event::is_error(&self.inner) |
| } |
| |
| /// Returns true if the event contains read closed readiness. |
| /// |
| /// # Notes |
| /// |
| /// Read closed readiness can be expected after any of the following have |
| /// occurred: |
| /// * The local stream has shutdown the read half of its socket |
| /// * The local stream has shutdown both the read half and the write half |
| /// of its socket |
| /// * The peer stream has shutdown the write half its socket; this sends a |
| /// `FIN` packet that has been received by the local stream |
| /// |
| /// Method is a best effort implementation. While some platforms may not |
| /// return readiness when read half is closed, it is guaranteed that |
| /// false-positives will not occur. |
| /// |
| /// The table below shows what flags are checked on what OS. |
| /// |
| /// | [OS selector] | Flag(s) checked | |
| /// |---------------|-----------------| |
| /// | [epoll] | `EPOLLHUP`, or | |
| /// | | `EPOLLIN` and `EPOLLRDHUP` | |
| /// | [kqueue] | `EV_EOF` | |
| /// |
| /// [OS selector]: ../struct.Poll.html#implementation-notes |
| /// [epoll]: https://man7.org/linux/man-pages/man7/epoll.7.html |
| /// [kqueue]: https://www.freebsd.org/cgi/man.cgi?query=kqueue&sektion=2 |
| pub fn is_read_closed(&self) -> bool { |
| sys::event::is_read_closed(&self.inner) |
| } |
| |
| /// Returns true if the event contains write closed readiness. |
| /// |
| /// # Notes |
| /// |
| /// On [epoll] this is essentially a check for `EPOLLHUP` flag as the |
| /// local stream shutting down its write half does not trigger this event. |
| /// |
| /// On [kqueue] the local stream shutting down the write half of its |
| /// socket will trigger this event. |
| /// |
| /// Method is a best effort implementation. While some platforms may not |
| /// return readiness when write half is closed, it is guaranteed that |
| /// false-positives will not occur. |
| /// |
| /// The table below shows what flags are checked on what OS. |
| /// |
| /// | [OS selector] | Flag(s) checked | |
| /// |---------------|-----------------| |
| /// | [epoll] | `EPOLLHUP`, or | |
| /// | | only `EPOLLERR`, or | |
| /// | | `EPOLLOUT` and `EPOLLERR` | |
| /// | [kqueue] | `EV_EOF` | |
| /// |
| /// [OS selector]: ../struct.Poll.html#implementation-notes |
| /// [epoll]: https://man7.org/linux/man-pages/man7/epoll.7.html |
| /// [kqueue]: https://www.freebsd.org/cgi/man.cgi?query=kqueue&sektion=2 |
| pub fn is_write_closed(&self) -> bool { |
| sys::event::is_write_closed(&self.inner) |
| } |
| |
| /// Returns true if the event contains priority readiness. |
| /// |
| /// # Notes |
| /// |
| /// Method is available on all platforms, but not all platforms trigger the |
| /// priority event. |
| /// |
| /// The table below shows what flags are checked on what OS. |
| /// |
| /// | [OS selector] | Flag(s) checked | |
| /// |---------------|-----------------| |
| /// | [epoll] | `EPOLLPRI` | |
| /// | [kqueue] | *Not supported* | |
| /// |
| /// [OS selector]: ../struct.Poll.html#implementation-notes |
| /// [epoll]: https://man7.org/linux/man-pages/man7/epoll.7.html |
| /// [kqueue]: https://www.freebsd.org/cgi/man.cgi?query=kqueue&sektion=2 |
| #[inline] |
| pub fn is_priority(&self) -> bool { |
| sys::event::is_priority(&self.inner) |
| } |
| |
| /// Returns true if the event contains AIO readiness. |
| /// |
| /// # Notes |
| /// |
| /// Method is available on all platforms, but not all platforms support AIO. |
| /// |
| /// The table below shows what flags are checked on what OS. |
| /// |
| /// | [OS selector] | Flag(s) checked | |
| /// |---------------|-----------------| |
| /// | [epoll] | *Not supported* | |
| /// | [kqueue]<sup>1</sup> | `EVFILT_AIO` | |
| /// |
| /// 1: Only supported on DragonFly BSD, FreeBSD, iOS and macOS. |
| /// |
| /// [OS selector]: ../struct.Poll.html#implementation-notes |
| /// [epoll]: https://man7.org/linux/man-pages/man7/epoll.7.html |
| /// [kqueue]: https://www.freebsd.org/cgi/man.cgi?query=kqueue&sektion=2 |
| pub fn is_aio(&self) -> bool { |
| sys::event::is_aio(&self.inner) |
| } |
| |
| /// Returns true if the event contains LIO readiness. |
| /// |
| /// # Notes |
| /// |
| /// Method is available on all platforms, but only FreeBSD supports LIO. On |
| /// FreeBSD this method checks the `EVFILT_LIO` flag. |
| pub fn is_lio(&self) -> bool { |
| sys::event::is_lio(&self.inner) |
| } |
| |
| /// Create a reference to an `Event` from a platform specific event. |
| pub(crate) fn from_sys_event_ref(sys_event: &sys::Event) -> &Event { |
| unsafe { |
| // This is safe because the memory layout of `Event` is |
| // the same as `sys::Event` due to the `repr(transparent)` attribute. |
| &*(sys_event as *const sys::Event as *const Event) |
| } |
| } |
| } |
| |
| /// When the [alternate] flag is enabled this will print platform specific |
| /// details, for example the fields of the `kevent` structure on platforms that |
| /// use `kqueue(2)`. Note however that the output of this implementation is |
| /// **not** consider a part of the stable API. |
| /// |
| /// [alternate]: fmt::Formatter::alternate |
| impl fmt::Debug for Event { |
| fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { |
| let alternate = f.alternate(); |
| let mut d = f.debug_struct("Event"); |
| d.field("token", &self.token()) |
| .field("readable", &self.is_readable()) |
| .field("writable", &self.is_writable()) |
| .field("error", &self.is_error()) |
| .field("read_closed", &self.is_read_closed()) |
| .field("write_closed", &self.is_write_closed()) |
| .field("priority", &self.is_priority()) |
| .field("aio", &self.is_aio()) |
| .field("lio", &self.is_lio()); |
| |
| if alternate { |
| struct EventDetails<'a>(&'a sys::Event); |
| |
| impl<'a> fmt::Debug for EventDetails<'a> { |
| fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { |
| sys::event::debug_details(f, self.0) |
| } |
| } |
| |
| d.field("details", &EventDetails(&self.inner)).finish() |
| } else { |
| d.finish() |
| } |
| } |
| } |
