Struct UserLabels 

pub struct UserLabels<const E: usize, const N: usize = 4> { /* private fields */ }

Shared registry of every endpoint’s UserLabel LabelList.

Persisted as a single TLV blob under USER_LABELS_KEY — every successful write to any UserLabelHandler re-serialises the whole registry and stores it. Read paths take the lock briefly to copy labels into the TLV builder.

Const generics:

• E — max number of endpoints that may have a LabelList. Bound on the in-memory Vec of per-endpoint slots.
• N — max number of LabelEntry rows per endpoint. Bound on each slot’s inner Vec. Defaults to 4.

Lock holds are bounded — the Mutex<RefCell<_>> is never held across an .await, so the registry is sound under a work-stealing executor.

Implementations

impl<const E: usize, const N: usize> UserLabels<E, N>

pub const fn new() -> UserLabels<E, N>

Create an empty registry. Call Self::load_persist at application startup to populate it from KV.

Prefer Self::init for non-trivial E * N so the registry’s storage can be initialised in-place (typically in a StaticCell) instead of being constructed on the stack and moved. The two paths produce structurally identical instances.

pub fn init() -> impl Init<UserLabels<E, N>>

Return an in-place initialiser for an empty registry. Use this when E * N * size_of::<LabelEntry> is large enough that stack-constructing a Self::new instance and moving it into long-lived storage would overflow the stack or bloat .rodata. Typical usage:

static USER_LABELS: StaticCell<UserLabels<8, 4>> = StaticCell::new();
let user_labels = USER_LABELS.uninit().init_with(UserLabels::init());

pub async fn load_persist<S>( &self, store: S, buf: &mut [u8], ) -> Result<(), Error>

where S: KvBlobStore,

Re-hydrate the registry from store under USER_LABELS_KEY. Call once at application startup, before exposing the data model to commissioners, so subsequent reads see the labels written before the last reboot.

Missing key (first boot, or persistence cleared) is not an error — the registry simply stays empty.

Trait Implementations

impl<const E: usize, const N: usize> Default for UserLabels<E, N>

fn default() -> UserLabels<E, N>

Returns the “default value” for a type.