https://x.com/NAKANO_Akihito/status/1809346992533041178

monitor_mutex.rs

struct MonitorMutex {
    inner: Mutex<RateLimiter>,
}

impl MonitorMutex {
    fn new(limiter: RateLimiter) -> Self {
        MonitorMutex {
            inner: Mutex::new(limiter),
        }
    }

    fn lock(&self) -> MutexGuard<RateLimiter> {
        let start = Instant::now();
        let guard = self.inner.lock();
        let duration = start.elapsed().as_nanos() as u64;
        println!("MonitorMutex:{}", duration);
        guard
    }
}

impl Deref for MonitorMutex {
    type Target = Mutex<RateLimiter>;

    fn deref(&self) -> &Self::Target {
        &self.inner
    }
}

impl DerefMut for MonitorMutex {
    fn deref_mut(&mut self) -> &mut Self::Target {
        &mut self.inner
    }
}