private async void SynchronizeDb()
{
var accounts = (await AccountProxy.GetAccountsAsync().ConfigureAwait(false)).ToArray();
var registered = _accountCache.Keys.ToArray();
var news = registered.Except(accounts).ToArray();
var olds = accounts.Except(registered).ToArray();
await Task.Run(() => Task.WaitAll(
olds.Select(AccountProxy.RemoveAccountAsync)
.Concat(news.Select(AccountProxy.AddAccountAsync))
.ToArray())).ConfigureAwait(false);
}