Make all endpoints to wait one exact endpoint

Question

I am using Moya to handle HTTP operations and normally I have an refreshToken(). I am checking token if expired or not when a request is about happen but the problem is there can be a scenarios that more than one requests. If they are chained with nested types it is not a problem however, it is not likely all the time.

To be more clear lets say I have request1() and request2() and assume that they execute separate operations and can be triggered anytime(for instance one is called in a viewDidLoad(), other one is called in another viewDidLoad()). when this happens and if the token is expired, my refresh request fails. (statusCode: 400) So, my question is, how can I make provider to wait refresh() operation get done?I mean by provider is other endpoints. I want them to wait refresh() endpoint if it is on.

I will be very appreciated if you suggest a way that will make this easier.

Answer 1

I just set an variable called isTokenRefreshing true when i start the refresh() operation and checked it before making a request. If it was true I stored all the requests in an array and when the refresh() is finished I executed another function which basically makes all the stored requests in a for loop.

If anyone wants to see the code I can share. Just let me know.

EDIT

This where I, NetworkManager, handle all my requests. It is in an Singleton class.

    private var awaitingRequests : [NetworkAPI] = []

    func makeRequest(_ request: NetworkAPI){
        if (Token.sharedInstance.isTokenRefreshing && request.requiresToken) {
            self.awaitingRequests.append(request)
            return
        }
        self.provider.request(){ result in ... }
    }

    func executeWaitedRequests(){
        for request in self.awaitingRequests {
            self.makeRequest(request)
        }
    }

NetworkAPI is main enum that I hold my endpoint cases. See the Moya documents if you do not what I am talking about.

And this is where I handle my Token operations.

class Token {

    static let sharedInstance = Token()

    private init(){}

    var isTokenRefreshing: Bool = false

    func refresh(_ completion: @escaping ()->()){

        self.isTokenRefreshing = true
        print("refreshing token")
        let queue = DispatchQueue(label: "com.asd.ads.makeRequest", attributes: DispatchQueue.Attributes.concurrent)
        queue.sync(flags: .barrier, execute: {
            NetworkManager.shared.makeRequest(.refresh(), completionHandler: { (success, error) in
                self.isTokenRefreshing = false
                if success{
                    completion()
                    NetworkManager.shared.executeWaitedRequests()
                }

                print("refrehing ended!")
            })
        })

    }
}