std/sys/sync/condvar/
futex.rsuse crate::sync::atomic::AtomicU32;
use crate::sync::atomic::Ordering::Relaxed;
use crate::sys::futex::{futex_wait, futex_wake, futex_wake_all};
use crate::sys::sync::Mutex;
use crate::time::Duration;
pub struct Condvar {
    futex: AtomicU32,
}
impl Condvar {
    #[inline]
    pub const fn new() -> Self {
        Self { futex: AtomicU32::new(0) }
    }
    pub fn notify_one(&self) {
        self.futex.fetch_add(1, Relaxed);
        futex_wake(&self.futex);
    }
    pub fn notify_all(&self) {
        self.futex.fetch_add(1, Relaxed);
        futex_wake_all(&self.futex);
    }
    pub unsafe fn wait(&self, mutex: &Mutex) {
        self.wait_optional_timeout(mutex, None);
    }
    pub unsafe fn wait_timeout(&self, mutex: &Mutex, timeout: Duration) -> bool {
        self.wait_optional_timeout(mutex, Some(timeout))
    }
    unsafe fn wait_optional_timeout(&self, mutex: &Mutex, timeout: Option<Duration>) -> bool {
        let futex_value = self.futex.load(Relaxed);
        mutex.unlock();
        let r = futex_wait(&self.futex, futex_value, timeout);
        mutex.lock();
        r
    }
}