Struct HlcHeader 

pub struct HlcHeader {
    pub magic: u64,
    pub capacity: u64,
    pub global_fence_physical: AtomicU64,
    pub global_fence_logical: AtomicU64,
    pub last_fence_epoch: AtomicU64,
    pub cached_us: AtomicU64,
    /* private fields */
}

Fields

magic: u64

capacity: u64

global_fence_physical: AtomicU64

global_fence_logical: AtomicU64

last_fence_epoch: AtomicU64

cached_us: AtomicU64

Shared cross-process cached wall clock. Each process publishes its own 250 us-fresh local cache here via fetch_max, so every process mapping this MMF reads the freshest timestamp across all of them - reconciling the per-process cache phase on a single host (where the hardware clock is shared, so there is no real skew, only phase). Monotonic by construction. Occupies 8 of the former 16 pad bytes, so the header size and magic are unchanged.