iOS

Question

所以我正在尝试为我的网络调用（第一层）构建一个重试函数。这是函数：

func retry<T>(_ attempts: Int, task: @escaping (_ success: @escaping (T) -> Void, _ failure: @escaping (String) -> Void) -> Void, success: @escaping (T) -> Void, failure: @escaping (String) -> Void) {
    task({ (obj) in
        success(obj)
    }) { (error) in
        print("Error retry left \(attempts)")
        if attempts > 1 {
            self.retry(attempts - 1, task: task, success: success, failure: failure)
        } else {
            failure(error)
        }
    }
}

实现是这样的：

func refreshSession(success: @escaping () -> Void, failure: @escaping (String) -> Void) {
    cameraProtocols?.refreshSession( success: {
        print("calling serverping")
        self.timer = Timer.scheduledTimer(withTimeInterval: 5.0, repeats: true, block: { (timer) in
            self.keepAlive(session: CameraManager.session, success: {
                print("serverping succsess")
                success()
            }, failure: { (error) in
                print(error)
                failure(error)
            })
        })
    }, failure: { (error) in
        print(error)
        failure(error)
    })
}

func keepAlive(session: String, success: @escaping () -> Void, failure: @escaping (String) -> Void) {
    cameraProtocols?.keepAlive(session: CameraManager.session, success: {
        print("server ping done!")
        NotificationCenter.default.post(name: Notification.Name(rawValue: "pingSuccess"), object: nil)
        success()
    }, failure: { (error) in
        print(error)
        self.retry(3, task: { (success, failure) in
            self.refreshSession(success: success, failure: failure)
        }, success: { (success) in
            print("refresh succsed from retry")
            success
        }, failure: { (e) in
            print("refresh failed from retry: \(e)")
            //TODO - handle error logic when to procced with the failure closure
            failure(error)
        })
        NotificationCenter.default.post(name: Notification.Name(rawValue: "faildPing"), object: nil)
    })
}

当我故意使 keepalive 调用失败时，重试不会按预期工作并且永远不会停止。

对新功能有什么建议或者如何修复吗？

Answer 1

我认为 CircuitBreaker Pattern 是您所需要的

断路器背后的基本思想非常简单。您将受保护的函数调用包装在断路器对象中，该对象会监视故障。一旦故障达到某个阈值，断路器就会跳闸，所有对断路器的进一步调用都会出错 return，根本不会进行受保护的调用

见this

Answer 2

所以我设法找到了问题所在。重试函数工作正常，但它会重复，因为我没有在 refreshSession 中停止计时器，所以在重复 3 次后它会重复。

iOS - 重试机制

iOS - retry mechanism

swift

retry-logic