Epoll type

Author: JonathanWoollett-Light

src/sys/epoll.rs

@@ -2,7 +2,7 @@ use crate::errno::Errno;
 use crate::Result;
 use libc::{self, c_int};
 use std::mem;
-use std::os::unix::io::RawFd;
+use std::os::unix::io::{FromRawFd,RawFd, OwnedFd, AsFd, AsRawFd};
 use std::ptr;
 
 libc_bitflags!(
@@ -26,6 +26,64 @@ libc_bitflags!(
     }
 );
 
+/// A safe wrapper around [`epoll`](https://man7.org/linux/man-pages/man7/epoll.7.html).
+/// ```
+/// # use nix::sys::{epoll::{Epoll, EpollEvent, EpollFlags, EpollCreateFlags}, eventfd::{eventfd, EfdFlags}};
+/// # use nix::unistd::write;
+/// # use std::os::unix::io::{OwnedFd, FromRawFd, AsRawFd, AsFd};
+/// # use std::time::{Instant, Duration};
+/// # fn main() -> nix::Result<()> {
+/// const DATA: u64 = 17;
+/// const MILLIS: u64 = 100;
+/// 
+/// // Create epoll
+/// let epoll = Epoll::new(EpollCreateFlags::empty())?;
+/// 
+/// // Create eventfd & Add event
+/// let eventfd = unsafe { OwnedFd::from_raw_fd(eventfd(0, EfdFlags::empty())?) };
+/// epoll.add(eventfd.as_fd(), EpollEvent::new(EpollFlags::EPOLLIN,DATA))?;
+/// 
+/// // Arm eventfd & Time wait
+/// write(eventfd.as_raw_fd(), &1u64.to_ne_bytes())?;
+/// let now = Instant::now();
+/// 
+/// // Wait on event
+/// let mut events = [EpollEvent::empty()];
+/// epoll.wait(&mut events, MILLIS);
+/// 
+/// // Assert data correct & timeout didn't occur
+/// assert_eq!(events[0].data(), DATA);
+/// assert!(now.elapsed() < Duration::from_millis(MILLIS));
+/// # Ok(())
+/// # }
+/// ```
+#[derive(Debug)]
+pub struct Epoll(pub OwnedFd);
+impl Epoll {
+    /// [`epoll_create1`].
+    pub fn new(flags: EpollCreateFlags) -> Result<Self> {
+        let fd = epoll_create1(flags)?;
+        let owned_fd = unsafe { OwnedFd::from_raw_fd(fd) };
+        Ok(Self(owned_fd))
+    }
+    /// [`epoll_ctl`] with [`EpollOp::EpollCtlAdd`].
+    pub fn add(&self,fd: impl AsFd, mut event: EpollEvent) -> Result<()> {
+        epoll_ctl(self.0.as_raw_fd(),EpollOp::EpollCtlAdd,fd.as_fd().as_raw_fd(),&mut event)
+    }
+    /// [`epoll_ctl`] with [`EpollOp::EpollCtlDel`].
+    pub fn delete(&self, fd: impl AsFd) -> Result<()> {
+        epoll_ctl(self.0.as_raw_fd(),EpollOp::EpollCtlDel,fd.as_fd().as_raw_fd(),None)
+    }
+    /// [`epoll_ctl`] with [`EpollOp::EpollCtlMod`].
+    pub fn modify(&self,fd: impl AsFd, event: &mut EpollEvent) -> Result<()> {
+        epoll_ctl(self.0.as_raw_fd(),EpollOp::EpollCtlMod,fd.as_fd().as_raw_fd(),event)
+    }
+    /// [`epoll_wait`]
+    pub fn wait(&self, events: &mut [EpollEvent], timeout: isize) -> Result<usize> {
+        epoll_wait(self.0.as_raw_fd(),events,timeout)
+    }
+}
+
 #[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)]
 #[repr(i32)]
 #[non_exhaustive]