joystream/storage-node/src/services/caching/tokenNonceKeeper.ts

import NodeCache from 'node-cache'

// Expiration period in seconds for the local nonce cache.
const TokenExpirationPeriod = 30 // seconds

// Max nonce number in local cache
const MaxNonces = 100000

// Local in-memory cache for nonces.
const nonceCache = new NodeCache({
  stdTTL: TokenExpirationPeriod,
  deleteOnExpire: true,
  maxKeys: MaxNonces,
})

/**
 * Constructs and returns an expiration time for a token.
 */
export function getTokenExpirationTime(): number {
  return Date.now() + 1000 * TokenExpirationPeriod
}

/**
 * Creates nonce string using the high precision process time and registers
 * it in the local in-memory cache with expiration time.
 *
 * @returns nonce string.
 */
export function createNonce(): string {
  const nonce = process.hrtime.bigint().toString()

  nonceCache.set(nonce, null, TokenExpirationPeriod)

  return nonce
}

/**
 * Removes the nonce from the local cache.
 *
 * @param nonce - nonce string.
 * @returns true if nonce was present in local cache.
 */
export function checkRemoveNonce(nonce: string): boolean {
  const deletedEntries = nonceCache.del(nonce)

  return deletedEntries > 0
}