index.js

'use strict'

const Lazy_KeyImage = function (
  mutable_keyImagesByCacheKey, // pass a mutable JS dictionary
  tx_pub_key,
  out_index,
  public_address,
  view_key__private,
  spend_key__public,
  spend_key__private,
  coreBridge_instance // must pass this so this fn can remain synchronous
) {
  var cache_index = tx_pub_key + ':' + public_address + ':' + out_index
  const cached__key_image = mutable_keyImagesByCacheKey[cache_index]
  if (
    typeof cached__key_image !== 'undefined' &&
		cached__key_image !== null
  ) {
    return cached__key_image
  }
  var key_image = coreBridge_instance.generate_key_image(
    tx_pub_key,
    view_key__private,
    spend_key__public,
    spend_key__private,
    out_index
  )
  // cache:
  mutable_keyImagesByCacheKey[cache_index] = key_image
  //
  return key_image
}
exports.Lazy_KeyImage = Lazy_KeyImage
//
//
// Managed caches - Can be used by apps which can't send a mutable_keyImagesByCacheKey
const __global_managed_keyImageCaches_by_walletId = {}
function _managedKeyImageCacheWalletIdForWalletWith (public_address) {
  // NOTE: making the assumption that public_address is unique enough to identify a wallet for caching....
  // FIXME: with subaddresses, is that still the case? would we need to split them up by subaddr anyway?
  if (
    public_address == '' ||
		!public_address ||
		typeof public_address === 'undefined'
  ) {
    throw 'managedKeyImageCacheIdentifierForWalletWith: Illegal public_address'
  }
  return '' + public_address
}

const Lazy_KeyImageCacheForWalletWith = function (public_address) {
  var cacheId = _managedKeyImageCacheWalletIdForWalletWith(public_address)
  var cache = __global_managed_keyImageCaches_by_walletId[cacheId]
  if (typeof cache === 'undefined' || !cache) {
    cache = {}
    __global_managed_keyImageCaches_by_walletId[cacheId] = cache
  }
  return cache
}
exports.Lazy_KeyImageCacheForWalletWith = Lazy_KeyImageCacheForWalletWith

const DeleteManagedKeyImagesForWalletWith = function (public_address) {
  // IMPORTANT: Ensure you call this method when you want to clear your wallet from
  // memory or delete it, or else you could leak key images and public addresses.
  const cacheId = _managedKeyImageCacheWalletIdForWalletWith(public_address)
  delete __global_managed_keyImageCaches_by_walletId[cacheId]
  //
  const cache = __global_managed_keyImageCaches_by_walletId[cacheId]
  if (typeof cache !== 'undefined') {
    throw 'Key image cache still exists after deletion'
  }
}
exports.DeleteManagedKeyImagesForWalletWith = DeleteManagedKeyImagesForWalletWith