Struct NotificationSlot 

pub struct NotificationSlot { /* private fields */ }

Per-source notification slot with atomic sequence counter.

Occupies exactly one cache line (64 bytes) to prevent false sharing when multiple slots are stored contiguously in NotificationHub.

Layout

offset  0: sequence   (AtomicU64, 8 bytes)
offset  8: source_id  (u32, 4 bytes)
offset 12: active     (AtomicBool, 1 byte)
offset 13: _pad       ([u8; 51])
total: 64 bytes = 1 cache line

Thread Safety

• notify() is called from Ring 0 (single writer per slot).
• current_sequence() is called from Ring 1 (readers).
• deactivate() / reactivate() are Ring 2 lifecycle operations.

Implementations

impl NotificationSlot

pub const fn new(source_id: u32) -> Self

Creates a new notification slot for the given source.

Initial state: sequence = 0, active = true.

pub fn notify(&self) -> u64

Increments the sequence counter and returns the new value.

This is the Ring 0 hot-path operation: a single fetch_add with Release ordering so that Ring 1 readers see the updated sequence.

pub fn current_sequence(&self) -> u64

Returns the current sequence number (Acquire load).

pub fn source_id(&self) -> u32

Returns the source identifier.

pub fn is_active(&self) -> bool

Returns true if this slot is active.

pub fn deactivate(&self)

Marks this slot as inactive (Ring 2 lifecycle operation).

Inactive slots are skipped by NotificationHub::notify_source.

pub fn reactivate(&self)

Re-activates a previously deactivated slot (Ring 2 lifecycle operation).