56 lines
1.5 KiB
Rust
56 lines
1.5 KiB
Rust
//! Uses the `timerfd` crate to sleep using an OS timer.
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//!
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//! Run with:
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//!
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//! ```
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//! cargo run --example linux-timerfd
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//! ```
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#[cfg(target_os = "linux")]
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fn main() -> std::io::Result<()> {
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use std::io;
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use std::os::unix::io::AsRawFd;
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use std::time::{Duration, Instant};
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use async_io::Async;
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use futures_lite::future;
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use timerfd::{SetTimeFlags, TimerFd, TimerState};
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/// Converts a [`nix::Error`] into [`std::io::Error`].
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fn io_err(err: nix::Error) -> io::Error {
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match err {
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nix::Error::Sys(code) => code.into(),
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err => io::Error::new(io::ErrorKind::Other, Box::new(err)),
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}
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}
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/// Sleeps using an OS timer.
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async fn sleep(dur: Duration) -> io::Result<()> {
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// Create an OS timer.
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let mut timer = TimerFd::new()?;
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timer.set_state(TimerState::Oneshot(dur), SetTimeFlags::Default);
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// When the OS timer fires, a 64-bit integer can be read from it.
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Async::new(timer)?
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.read_with(|t| nix::unistd::read(t.as_raw_fd(), &mut [0u8; 8]).map_err(io_err))
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.await?;
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Ok(())
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}
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future::block_on(async {
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let start = Instant::now();
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println!("Sleeping...");
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// Sleep for a second using an OS timer.
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sleep(Duration::from_secs(1)).await?;
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println!("Woke up after {:?}", start.elapsed());
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Ok(())
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})
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}
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#[cfg(not(target_os = "linux"))]
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fn main() {
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println!("This example works only on Linux!");
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}
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