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refactor: make Epoll take BorrowedFd #2232

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refactor: make Epoll take BorrowedFd #2232

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02f11dc
refactor: make Epoll take BorrowedFd
SteveLauC Nov 27, 2023
23e6f4c
update test and changelog
SteveLauC Nov 28, 2023
de313b3
update test func name
SteveLauC Nov 28, 2023
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48 changes: 34 additions & 14 deletions src/sys/epoll.rs
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Expand Up @@ -3,7 +3,8 @@ pub use crate::poll_timeout::PollTimeout as EpollTimeout;
use crate::Result;
use libc::{self, c_int};
use std::mem;
use std::os::unix::io::{AsFd, AsRawFd, FromRawFd, OwnedFd, RawFd};
use std::os::fd::{AsFd, BorrowedFd};
use std::os::unix::io::{AsRawFd, FromRawFd, OwnedFd, RawFd};

libc_bitflags!(
pub struct EpollFlags: c_int {
Expand Down Expand Up @@ -85,7 +86,7 @@ impl EpollEvent {
///
/// // Create eventfd & Add event
/// let eventfd = eventfd(0, EfdFlags::empty())?;
/// epoll.add(&eventfd, EpollEvent::new(EpollFlags::EPOLLIN,DATA))?;
/// epoll.add(eventfd.as_fd(), EpollEvent::new(EpollFlags::EPOLLIN,DATA))?;
///
/// // Arm eventfd & Time wait
/// write(&eventfd, &1u64.to_ne_bytes())?;
Expand All @@ -102,37 +103,50 @@ impl EpollEvent {
/// # }
/// ```
#[derive(Debug)]
pub struct Epoll(pub OwnedFd);
impl Epoll {
#[repr(transparent)]
pub struct Epoll<'fd> {
epoll_fd: OwnedFd,
_fds: std::marker::PhantomData<*mut &'fd ()>,
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@SteveLauC SteveLauC Nov 27, 2023 •
edited

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We cannot use _fds: std::marker::PhantomData<BorrowedFd<'fd>> here or the following code would compile without any issue:

use nix::sys::epoll::{Epoll, EpollCreateFlags, EpollEvent};
use nix::unistd::pipe;

fn main() {
    let (r, _w) = pipe().unwrap();
    let epoll = Epoll::new(EpollCreateFlags::empty()).unwrap();
    epoll.add(r, EpollEvent::empty()).unwrap();

    drop(r);
    drop(epoll);
}

I haven't figured out the reason, but using an invariant type here would work

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Friendly ping @asomers, do you have any idea about this?

}

impl<'fd> Epoll<'fd> {
/// Creates a new epoll instance and returns a file descriptor referring to that instance.
///
/// [`epoll_create1`](https://man7.org/linux/man-pages/man2/epoll_create1.2.html).
pub fn new(flags: EpollCreateFlags) -> Result<Self> {
let res = unsafe { libc::epoll_create1(flags.bits()) };
let fd = Errno::result(res)?;
let owned_fd = unsafe { OwnedFd::from_raw_fd(fd) };
Ok(Self(owned_fd))

Ok(Self {
epoll_fd: owned_fd,
_fds: std::marker::PhantomData,
})
}
/// Add an entry to the interest list of the epoll file descriptor for
/// specified in events.
///
/// [`epoll_ctl`](https://man7.org/linux/man-pages/man2/epoll_ctl.2.html) with `EPOLL_CTL_ADD`.
pub fn add<Fd: AsFd>(&self, fd: Fd, mut event: EpollEvent) -> Result<()> {
pub fn add(
&self,
fd: BorrowedFd<'fd>,
mut event: EpollEvent,
) -> Result<()> {
self.epoll_ctl(EpollOp::EpollCtlAdd, fd, &mut event)
}
/// Remove (deregister) the target file descriptor `fd` from the interest list.
///
/// [`epoll_ctl`](https://man7.org/linux/man-pages/man2/epoll_ctl.2.html) with `EPOLL_CTL_DEL` .
pub fn delete<Fd: AsFd>(&self, fd: Fd) -> Result<()> {
pub fn delete(&self, fd: BorrowedFd<'fd>) -> Result<()> {
self.epoll_ctl(EpollOp::EpollCtlDel, fd, None)
}
/// Change the settings associated with `fd` in the interest list to the new settings specified
/// in `event`.
///
/// [`epoll_ctl`](https://man7.org/linux/man-pages/man2/epoll_ctl.2.html) with `EPOLL_CTL_MOD`.
pub fn modify<Fd: AsFd>(
pub fn modify(
&self,
fd: Fd,
fd: BorrowedFd<'fd>,
event: &mut EpollEvent,
) -> Result<()> {
self.epoll_ctl(EpollOp::EpollCtlMod, fd, event)
Expand All @@ -148,7 +162,7 @@ impl Epoll {
) -> Result<usize> {
let res = unsafe {
libc::epoll_wait(
self.0.as_raw_fd(),
self.epoll_fd.as_raw_fd(),
events.as_mut_ptr().cast(),
events.len() as c_int,
timeout.into().into(),
Expand All @@ -164,10 +178,10 @@ impl Epoll {
/// When possible prefer [`Epoll::add`], [`Epoll::delete`] and [`Epoll::modify`].
///
/// [`epoll_ctl`](https://man7.org/linux/man-pages/man2/epoll_ctl.2.html)
fn epoll_ctl<'a, Fd: AsFd, T>(
fn epoll_ctl<'a, T>(
&self,
op: EpollOp,
fd: Fd,
fd: BorrowedFd<'fd>,
event: T,
) -> Result<()>
where
Expand All @@ -179,16 +193,22 @@ impl Epoll {
.unwrap_or(std::ptr::null_mut());
unsafe {
Errno::result(libc::epoll_ctl(
self.0.as_raw_fd(),
self.epoll_fd.as_raw_fd(),
op as c_int,
fd.as_fd().as_raw_fd(),
fd.as_raw_fd(),
ptr,
))
.map(drop)
}
}
}

impl AsFd for Epoll<'_> {
fn as_fd(&self) -> BorrowedFd<'_> {
self.epoll_fd.as_fd()
}
}

#[deprecated(since = "0.27.0", note = "Use Epoll::new() instead")]
#[inline]
pub fn epoll_create() -> Result<RawFd> {
Expand Down