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|
use std::{
os::fd::{AsFd, AsRawFd, OwnedFd},
slice,
};
use nix::{errno::Errno, fcntl::OFlag, poll, unistd};
use common::error::*;
use super::util::unix;
#[derive(Debug)]
pub struct Jobserver {
tokens: usize,
r: OwnedFd,
w: OwnedFd,
}
impl Jobserver {
pub fn new(tokens: usize) -> Result<Jobserver> {
let (r, w) = unistd::pipe2(OFlag::O_CLOEXEC | OFlag::O_NONBLOCK).context("pipe()")?;
for _ in 0..tokens {
if unistd::write(w.as_fd(), b"+").is_err() {
break;
}
}
unix::set_blocking(&w, true)?;
Ok(Jobserver { tokens, r, w })
}
pub fn wait(&mut self) -> u8 {
loop {
poll::poll(
&mut [poll::PollFd::new(self.r.as_fd(), poll::PollFlags::POLLIN)],
poll::PollTimeout::NONE,
)
.expect("poll()");
let mut token = 0;
match unistd::read(self.r.as_raw_fd(), slice::from_mut(&mut token)) {
Ok(n) => {
assert!(n == 1);
return token;
}
Err(Errno::EAGAIN) => {
// Token was sniped by another task
continue;
}
error @ Err(_) => {
error.expect("read()");
}
}
}
}
pub fn post(&mut self, token: u8) {
let n = unistd::write(self.w.as_fd(), slice::from_ref(&token)).expect("write()");
assert!(n == 1);
}
pub fn set_cloexec(&mut self, cloexec: bool) -> Result<()> {
unix::set_cloexec(&self.r, cloexec)?;
unix::set_cloexec(&self.w, cloexec)?;
Ok(())
}
pub fn to_makeflags(&self) -> String {
format!(
" -j{} --jobserver-auth={},{}",
self.tokens,
self.r.as_raw_fd(),
self.w.as_raw_fd(),
)
}
}
// FIXME Log lost tokens on drop
|
