Method try_reserve

nodedb-mem/src/governor.rs:72–88

Attempt a CAS-based reservation. Returns the `Arc` to the counter on success so the token can hold a reference for drop-release.

(&self, size: usize)

    /// Attempt a CAS-based reservation. Returns the `Arc` to the counter on
    /// success so the token can hold a reference for drop-release.
    fn try_reserve(&self, size: usize) -> Option<Arc<AtomicUsize>> {
        loop {
            let current = self.allocated.load(Ordering::Relaxed);
            if current + size > self.limit {
                return None;
            }
            match self.allocated.compare_exchange_weak(
                current,
                current + size,
                Ordering::AcqRel,
                Ordering::Relaxed,
            ) {
                Ok(_) => return Some(Arc::clone(&self.allocated)),
                Err(_) => continue,
            }
        }
    }

    fn available(&self) -> usize {
        let alloc = self.allocated.load(Ordering::Relaxed);