Method for maintaining account consistency

摘要

In an account transaction such as an ATM transaction, a server in communication with an ATM stores a copy of the account balance. Before processing the transaction, the server reads the balance from memory and determines whether the account contains sufficient funds for the transaction. In order to prevent overdrawing of the account, the server makes any balance update predicated on the fact that the current balance in the account database is the same as the balance of the local copy of the account. If the account balance stored in the database is not the same, the server rolls back the request and updates the account balance stored in the local copy. This process continues until either the account balance is updated or the transaction is aborted.