Struct EventFd

pub struct EventFd { /* private fields */ }

A safe wrapper around Linux eventfd.

Implementations

impl EventFd

pub fn new(flag: i32) -> Result<EventFd, Error>

Create a new EventFd with an initial value.

Arguments

• flag: The initial value used for creating the EventFd. Refer to Linux eventfd.

Examples

extern crate vmm_sys_util;
use vmm_sys_util::eventfd::{EventFd, EFD_NONBLOCK};

EventFd::new(EFD_NONBLOCK).unwrap();

pub fn write(&self, v: u64) -> Result<(), Error>

Add a value to the eventfd’s counter.

When the addition causes the counter overflow, this would either block until a read is performed on the file descriptor, or fail with the error EAGAIN if the file descriptor has been made nonblocking.

Arguments

• v: the value to be added to the eventfd’s counter.

Examples

extern crate vmm_sys_util;
use vmm_sys_util::eventfd::{EventFd, EFD_NONBLOCK};

let evt = EventFd::new(EFD_NONBLOCK).unwrap();
evt.write(55).unwrap();

pub fn read(&self) -> Result<u64, Error>

Read a value from the eventfd.

If the counter is zero, this would either block until the counter becomes nonzero, or fail with the error EAGAIN if the file descriptor has been made nonblocking.

Examples

extern crate vmm_sys_util;
use vmm_sys_util::eventfd::{EventFd, EFD_NONBLOCK};

let evt = EventFd::new(EFD_NONBLOCK).unwrap();
evt.write(55).unwrap();
assert_eq!(evt.read().unwrap(), 55);

pub fn try_clone(&self) -> Result<EventFd, Error>

Clone this EventFd.

This internally creates a new file descriptor and it will share the same underlying count within the kernel.

Examples

extern crate vmm_sys_util;
use vmm_sys_util::eventfd::{EventFd, EFD_NONBLOCK};

let evt = EventFd::new(EFD_NONBLOCK).unwrap();
let evt_clone = evt.try_clone().unwrap();
evt.write(923).unwrap();
assert_eq!(evt_clone.read().unwrap(), 923);

Trait Implementations

impl AsRawFd for EventFd

fn as_raw_fd(&self) -> RawFd

Extracts the raw file descriptor.

impl Debug for EventFd

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl FromRawFd for EventFd

unsafe fn from_raw_fd(fd: RawFd) -> Self

Constructs a new instance of Self from the given raw file descriptor.