solana-program-runtime 4.1.0-beta.1

Solana program runtime
Documentation 
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use solana_svm_type_overrides::sync::{Condvar, Mutex};

#[derive(Copy, Clone, Debug, Default, Eq, PartialEq)]
pub struct LoadingTaskCookie(u64);

impl LoadingTaskCookie {
    fn new() -> Self {
        Self(0)
    }

    fn update(&mut self) {
        let LoadingTaskCookie(cookie) = self;
        *cookie = cookie.wrapping_add(1);
    }
}

/// Suspends the thread in case no cooprative loading task was assigned
#[derive(Debug, Default)]
pub struct LoadingTaskWaiter {
    cookie: Mutex<LoadingTaskCookie>,
    cond: Condvar,
}

impl LoadingTaskWaiter {
    pub fn new() -> Self {
        Self {
            cookie: Mutex::new(LoadingTaskCookie::new()),
            cond: Condvar::new(),
        }
    }

    pub fn cookie(&self) -> LoadingTaskCookie {
        *self.cookie.lock().unwrap()
    }

    pub fn notify(&self) {
        let mut cookie = self.cookie.lock().unwrap();
        cookie.update();
        self.cond.notify_all();
    }

    pub fn wait(&self, cookie: LoadingTaskCookie) -> LoadingTaskCookie {
        let cookie_guard = self.cookie.lock().unwrap();
        *self
            .cond
            .wait_while(cookie_guard, |current_cookie| *current_cookie == cookie)
            .unwrap()
    }
}