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Reduce syscalls in blocking_fd

This commit is contained in:
Taiki Endo 2022-12-30 13:39:01 +09:00
parent 73f3f8f308
commit 7980b4696a
1 changed files with 17 additions and 2 deletions
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19
src/lib.rs
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@ -1063,8 +1063,23 @@ impl fmt::Debug for Command {
/// Moves `Fd` out of non-blocking mode.
#[cfg(unix)]
fn blocking_fd(fd: rustix::fd::BorrowedFd<'_>) -> io::Result<()> {
let flags = rustix::fs::fcntl_getfl(fd)?;
rustix::fs::fcntl_setfl(fd, flags & !rustix::fs::OFlags::NONBLOCK)?;
cfg_if::cfg_if! {
// ioctl(FIONBIO) sets the flag atomically, but we use this only on Linux
// for now, as with the standard library, because it seems to behave
// differently depending on the platform.
// https://github.com/rust-lang/rust/commit/efeb42be2837842d1beb47b51bb693c7474aba3d
// https://github.com/libuv/libuv/blob/e9d91fccfc3e5ff772d5da90e1c4a24061198ca0/src/unix/poll.c#L78-L80
// https://github.com/tokio-rs/mio/commit/0db49f6d5caf54b12176821363d154384357e70a
if #[cfg(target_os = "linux")] {
rustix::io::ioctl_fionbio(fd, false)?;
} else {
let previous = rustix::fs::fcntl_getfl(fd)?;
let new = previous & !rustix::fs::OFlags::NONBLOCK;
if new != previous {
rustix::fs::fcntl_setfl(fd, new)?;
}
}
}
Ok(())
}