Struct SagaIdempotencyLru 

pub struct SagaIdempotencyLru {
    entries: VecDeque<((u64, CommandKind), Command)>,
    cap: usize,
}

Idempotency LRU keyed by (saga_id, CommandKind). Stores the resulting Report* Command so a duplicate dispatch re-emits the same reply payload without re-running the action.

Implementation: simple VecDeque of (key, report) pairs. Front is oldest, back is most-recent. Linear scan on lookup is fine at cap=256: the entire scan is a few microseconds and only happens once per saga command (a human-rate event).

Fields

entries: VecDeque<((u64, CommandKind), Command)>

cap: usize

Implementations

impl SagaIdempotencyLru

pub fn new(cap: usize) -> Self

pub fn with_default_cap() -> Self

pub fn get(&mut self, saga_id: u64, kind: CommandKind) -> Option<Command>

Look up the cached Report for (saga_id, kind). On hit, promotes the entry to most-recent (back of the deque) and returns a clone of the cached Report. On miss, returns None.

pub fn insert(&mut self, saga_id: u64, kind: CommandKind, report: Command)

Cache the Report for (saga_id, kind). If at capacity, drops the oldest entry (front). If a duplicate key exists, updates in place + promotes (defensive — caller usually hits via get first; this branch covers a race where two duplicate commands raced through get with both seeing miss).

pub fn len(&self) -> usize

Current number of entries (for tests + diagnostics).

Trait Implementations

impl Default for SagaIdempotencyLru

fn default() -> Self

Returns the “default value” for a type.