Method alloc_one

nodedb/src/control/surrogate/registry.rs:91–105

Allocate a single surrogate. Returns `Exhausted` if the u32 space is full.

(&self)

    /// Allocate a single surrogate. Returns `Exhausted` if the u32 space
    /// is full.
    pub fn alloc_one(&self) -> Result<Surrogate, SurrogateAllocError> {
        let prev = self.counter.fetch_add(1, Ordering::AcqRel);
        if prev > u64::from(u32::MAX) {
            // Restore the counter so future callers also see Exhausted
            // rather than racing past us into a wrapped value. We don't
            // need atomicity with the racing increments — once any caller
            // observes `prev > u32::MAX`, the space is effectively dead.
            self.counter
                .store(u64::from(u32::MAX) + 1, Ordering::Release);
            return Err(SurrogateAllocError::Exhausted);
        }
        self.allocs_since_flush.fetch_add(1, Ordering::AcqRel);
        // Safe: prev <= u32::MAX is guaranteed by the check above.
        Ok(Surrogate::new(prev as u32))
    }

    /// Allocate `n` contiguous surrogates as an inclusive range.
    /// Returns `EmptyBatch` for `n == 0`, `Exhausted` if the batch