Struct SettlementCache 

pub struct SettlementCache { /* private fields */ }

Available on crate feature cache only.

Chain-agnostic deduplication cache for facilitator settlement requests.

Wraps TtlSet with the canonical x402 v2 TTL (DEFAULT_SETTLEMENT_TTL) and capacity (DEFAULT_SETTLEMENT_CAPACITY). Used by every chain crate to defend against duplicate / replayed /settle calls within the on-chain replay window:

• EVM exact — keyed by chain:nonce_hex (the EIP-3009 nonce binds one-shot to a single token + payer pair).
• EVM upto — keyed by chain:permit2_nonce_hex.
• SVM exact — keyed by the base64 transaction payload.

The cache is in-memory only. A facilitator deployment that spans multiple processes must either pin requests to a single worker or replace this cache with a Redis-backed implementation by wiring its own TtlSet-equivalent through the same trait surface.

Implementations

impl SettlementCache

pub fn new() -> Self

Constructs a cache with the spec-recommended TTL and capacity.

pub fn with_params(ttl: Duration, capacity: u64) -> Self

Constructs a cache with custom TTL and capacity.

pub fn reserve(&self, key: impl Into<String>) -> Duplicate

Atomically reserves the key. Returns Duplicate::No when newly inserted (caller may proceed) or Duplicate::Yes when the key is already present (caller must abort with DuplicateSettlement).

Increments the r402_settlement_cache_reserve_total counter with outcome=inserted|duplicate when the metrics feature is enabled.

pub fn entry_count(&self) -> u64

Returns the approximate current entry count (observability hook).

Trait Implementations

impl Clone for SettlementCache

fn clone(&self) -> SettlementCache

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for SettlementCache

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for SettlementCache

fn default() -> Self

Returns the “default value” for a type.