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use std::io;
use std::process::Command;
use std::sync::{Arc, Condvar, Mutex};
use std::thread::{Builder, JoinHandle};
#[derive(Debug)]
pub struct Client {
inner: Arc<Inner>,
}
#[derive(Debug)]
struct Inner {
count: Mutex<usize>,
cvar: Condvar,
}
#[derive(Debug)]
pub struct Acquired(());
impl Client {
pub fn new(limit: usize) -> io::Result<Client> {
Ok(Client {
inner: Arc::new(Inner {
count: Mutex::new(limit),
cvar: Condvar::new(),
}),
})
}
pub unsafe fn open(_s: &str) -> Option<Client> {
None
}
pub fn acquire(&self) -> io::Result<Acquired> {
let mut lock = self.inner.count.lock().unwrap_or_else(|e| e.into_inner());
while *lock == 0 {
lock = self
.inner
.cvar
.wait(lock)
.unwrap_or_else(|e| e.into_inner());
}
*lock -= 1;
Ok(Acquired(()))
}
pub fn release(&self, _data: Option<&Acquired>) -> io::Result<()> {
let mut lock = self.inner.count.lock().unwrap_or_else(|e| e.into_inner());
*lock += 1;
drop(lock);
self.inner.cvar.notify_one();
Ok(())
}
pub fn string_arg(&self) -> String {
panic!(
"On this platform there is no cross process jobserver support,
so Client::configure is not supported."
);
}
pub fn available(&self) -> io::Result<usize> {
let lock = self.inner.count.lock().unwrap_or_else(|e| e.into_inner());
Ok(*lock)
}
pub fn configure(&self, _cmd: &mut Command) {
unreachable!();
}
}
#[derive(Debug)]
pub struct Helper {
thread: JoinHandle<()>,
}
pub(crate) fn spawn_helper(
client: crate::Client,
state: Arc<super::HelperState>,
mut f: Box<dyn FnMut(io::Result<crate::Acquired>) + Send>,
) -> io::Result<Helper> {
let thread = Builder::new().spawn(move || {
state.for_each_request(|_| f(client.acquire()));
})?;
Ok(Helper { thread: thread })
}
impl Helper {
pub fn join(self) {
// TODO: this is not correct if the thread is blocked in
// `client.acquire()`.
drop(self.thread.join());
}
}