Struct MonitorGuard 

pub struct MonitorGuard<'a, T> { /* private fields */ }

Guard returned by Monitor::lock.

MonitorGuard is the monitor-specific counterpart of parking_lot::MutexGuard. While it exists, the protected state is locked. Dropping the guard releases the lock. It implements Deref and DerefMut, so callers can read and mutate the protected state as if they held &T or &mut T.

Unlike a raw MutexGuard, this guard also remembers the monitor that created it. That lets Self::wait and Self::wait_timeout release and reacquire the correct mutex with the correct condition variable.

Type Parameters

• T - The state protected by the monitor.

Example

use qubit_lock::lock::Monitor;

let monitor = Monitor::new(Vec::new());
{
    let mut items = monitor.lock();
    items.push("first");
}

assert_eq!(monitor.read(|items| items.len()), 1);

Implementations

impl<'a, T> MonitorGuard<'a, T>

pub fn wait(self) -> Self

Waits for a notification while temporarily releasing the monitor lock.

This method consumes the current guard, calls the underlying parking_lot::Condvar::wait, and returns the guard after the lock has been reacquired. It is intended for explicit guarded-suspension loops where the caller needs to inspect or update state before and after waiting.

The method may block indefinitely if no notification is sent. Callers should still use it inside a loop that re-checks the protected state so notifications that do not make progress are handled correctly.

Returns

A new guard holding the monitor lock after the wait returns.

Example

use std::{
    sync::Arc,
    thread,
};

use qubit_lock::lock::Monitor;

let monitor = Arc::new(Monitor::new(false));
let waiter_monitor = Arc::clone(&monitor);

let waiter = thread::spawn(move || {
    let mut ready = waiter_monitor.lock();
    while !*ready {
        ready = ready.wait();
    }
    *ready = false;
});

{
    let mut ready = monitor.lock();
    *ready = true;
}
monitor.notify_one();

waiter.join().expect("waiter should finish");
assert!(!monitor.read(|ready| *ready));

pub fn wait_timeout(self, timeout: Duration) -> (Self, WaitTimeoutStatus)

Waits for a notification or timeout while temporarily releasing the lock.

This method consumes the current guard, calls the underlying parking_lot::Condvar::wait_for, and returns the guard after the lock has been reacquired. The status reports whether the wait reached the timeout boundary or returned earlier.

A WaitTimeoutStatus::Woken result does not prove that another thread changed the state. A WaitTimeoutStatus::TimedOut result also does not remove the need to inspect the state, because another thread may have changed it while this thread was reacquiring the lock.

Arguments

• timeout - Maximum duration to wait before returning WaitTimeoutStatus::TimedOut.

Returns

A tuple containing the reacquired guard and the timed-wait status.

Example

use std::time::Duration;

use qubit_lock::lock::{Monitor, WaitTimeoutStatus};

let monitor = Monitor::new(0);
let guard = monitor.lock();
let (guard, status) = guard.wait_timeout(Duration::from_millis(1));

assert_eq!(*guard, 0);
assert_eq!(status, WaitTimeoutStatus::TimedOut);

Trait Implementations

impl<T> Deref for MonitorGuard<'_, T>

fn deref(&self) -> &Self::Target

Returns an immutable reference to the protected state.

type Target = T

The resulting type after dereferencing.

impl<T> DerefMut for MonitorGuard<'_, T>

fn deref_mut(&mut self) -> &mut Self::Target

Returns a mutable reference to the protected state.