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HarmonyOS Next Financial System: Generic-based transaction core development

In HarmonyOS Next development, building an efficient and secure financial system is crucial, and the generic design concept can bring strong flexibility and scalability to the transaction core of the financial system.As a technical expert who has been deeply involved in the field of financial technology for many years, I will discuss in depth how to use generic technology to develop the core of financial system transactions, including key aspects such as type abstraction, transaction security guarantee, and performance optimization.

Chapter 1: Type Abstraction

In the financial system, different financial products and businesses involve multiple currency types, and using generics can achieve a highly reusable code structure.By defining the Account<T: Currency> generic class, you can abstract the general logic related to the account, where T represents a specific currency type and T must follow the Currency protocol.

protocol Currency {
// Define methods and attributes related to currency, such as currency symbols, minimum units, etc.
    func symbol() -> String
    func minUnit() -> Decimal
}

class Account<T: Currency> {
    private var balance: Decimal
    private var currency: T

    init(initialBalance: Decimal, currency: T) {
        self.balance = initialBalance
        self.currency = currency
    }

    func deposit(amount: Decimal) {
        if amount > 0 {
            self.balance += amount
        }
    }

    func withdraw(amount: Decimal) -> Bool {
        if amount > 0 && amount <= self.balance {
            self.balance -= amount
            return true
        }
        return false
    }

    func getBalance() -> String {
        return "\(self.balance) \(self.currency.symbol())"
    }
}
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In the above code, the properties and methods of the Account class depend on the generic parameter T.Regardless of the specific currency type (as long as it complies with the Currency protocol), the logic of the Account class can be reused.For example, you can define different currency types such as RMB and US dollar, and then create corresponding account instances:

struct RMB: Currency {
    func symbol() -> String {
        return "¥"
    }

    func minUnit() -> Decimal {
        return Decimal(0.01)
    }
}

struct USD: Currency {
    func symbol() -> String {
        return "$"
    }

    func minUnit() -> Decimal {
        return Decimal(0.01)
    }
}

let rmbAccount = Account<RMB>(initialBalance: Decimal(1000), currency: RMB())
let usdAccount = Account<USD>(initialBalance: Decimal(200), currency: USD())
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This type abstraction method greatly improves the maintainability and scalability of the code. When you need to add a new currency type, you only need to implement the Currency protocol without modifying the core logic of the Account class.

Chapter 2: Transaction Security

Financial transactions have extremely high requirements for data consistency and integrity. Immutable variables combined with software transaction memory (STM) are an effective solution to ensure transaction security.Immutable variables ensure that data is not accidentally modified when concurrent operations, while STM provides an atomic transaction processing mechanism.

import std.stm.*

func transfer<TA: Currency, TB: Currency>(from: Account<TA>, to: Account<TB>, amount: Decimal) {
    atomic {
        if from.withdraw(amount: amount) {
            to.deposit(amount: amount)
        }
    }
}
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In the transfer function, use the atomic block to wrap the funds transfer operation.The code in the atomic block will be executed as an atomic operation, either all succeed or all fail.In a concurrent environment, when multiple threads perform transfer operations at the same time, STM will ensure the atomicity and isolation of each transaction to avoid data inconsistency.For example, when multiple threads try to transfer money from one account to another at the same time, the STM coordinates these operations to ensure that the balance changes in each account are correct and there will be no duplicate deductions or funds loss.

Chapter 3: Performance pressure measurement

In a financial system, handling large-scale transaction records is a huge challenge to system performance.VArray, as a value type array, has unique performance advantages compared to traditional reference type arrays when storing a large number of transaction records.By optimizing the VArray memory of million-level transaction records, the performance of the system can be significantly improved.

struct Transaction {
    var amount: Decimal
    var timestamp: Int64
    var fromAccount: String
    var toAccount: String
}

func testVArrayPerformance() {
    let numTransactions = 1000000
    var transactions: VArray<Transaction, $numTransactions> = VArray(item: Transaction(amount: Decimal(0), timestamp: 0, fromAccount: "", toAccount: ""))

    for (i in 0..numTransactions) {
        transactions[i] = Transaction(amount: Decimal(i), timestamp: Int64(i), fromAccount: "account\(i)", toAccount: "account\((i + 1) % numTransactions)")
    }

// Simulate the processing of transaction records, such as counting the total transaction amount
    var totalAmount: Decimal = Decimal(0)
    for (transaction in transactions) {
        totalAmount += transaction.amount
    }

println("Total Amount of Million-level Transaction Records: \(totalAmount)")
}
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In the above code, use VArray to store millions of transaction records.Because VArray continuously stores data on the stack, access speed is fast and reduces the overhead of heap memory allocation and garbage collection, thereby improving the processing efficiency of large transaction records.In actual financial systems, the rapid processing and storage of transaction records are key indicators of system performance. By rationally using VArray for memory optimization, the overall performance of the system can be effectively improved.

The core of financial system transactions is developed based on generics, code reuse is realized through type abstraction, transaction security is ensured using immutable variables and STMs, and performance pressure measurement and optimization with the help of VArray can be constructed to build an efficient, secure and scalable financial system to meet the complex and changing business needs of the financial industry.

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