public void ProcessTrade(Trade sale)
 {
     //Thread.Sleep(300);
     if (sale.QuantitySold > 0)
         _salesByPerson.AddOrUpdate(sale.Person, sale.QuantitySold, (key, value) => value + sale.QuantitySold);
     else
         _purchasesByPerson.AddOrUpdate(sale.Person, -sale.QuantitySold, (key, value) => value - sale.QuantitySold);
 }
 public void AddTrade(Trade transaction)
 {
     _queue.Add(transaction);
 }