pub const NONCE_CACHE_SHARDS: usize = 16;Expand description
Number of independent shard locks in the nonce cache. Fixed (not
CPU-count-derived) so the worst-case entry bound
(NONCE_CACHE_SHARDS * MAX_NONCE_CACHE_ENTRIES_PER_SHARD) is the
same number on every machine — the GCRA store’s rationale.