//! A monotonic marker for cache invalidation.
/// A cache-invalidation marker: bumped when the underlying data changes,
/// compared by caches to notice they are stale.
#[derive(Clone, Copy, Debug, Default, PartialEq, Eq, Hash)]pubstructGeneration(u64);implGeneration{/// Moves this marker on, invalidating everything built against the old one.
pubfnbump(&mutself){self.0=self.0.wrapping_add(1);}}