Function async_io::os::unix::reactor_fd

pub fn reactor_fd() -> Option<BorrowedFd<'static>>

Get a file descriptor that can be used to wait for readiness in an external runtime.

This file descriptor is equivalent to the one used by the underlying epoll/kqueue/event ports instance for polling. The intention is that this file descriptor can be registered into an external runtime (like calloop or GLib) so that async-io can be seamlessly polled alongside the other runtime.

Not every backend used on unix has an associated file descriptor, however. While epoll, kqueue and event ports have a file descriptor as a backend, on some Unix systems async-io will use the poll() system call instead. Since there are no file descriptors intrinsically associated with poll(), this function will return None.

There is presently no way to stop the “async-io” thread from being launched, so the reactor will still be continiously polled on that thread. This fact should be kept in mind by anyone looking to integrate async-io into another runtime using this function.

It is possible to use this function to call raw system calls on the underlying event source. This is generally not recommended, since registered event sources may conflict with async-io’s existing scheme for managing sources. The behavior resulting from this is not specified, but will not result in undefined behavior. This could include panics, incorrect results, aborts, memory leaks, and non-termination.

Example

#![cfg(unix)]

use async_io::os::unix::reactor_fd;

my_runtime::register(reactor_fd().unwrap());