Delay until await returns a True-CodePudding

Delay until await returns a True

I have looked at many examples of Delaying a for while loop until a result is gained; but can't come up with a solution that will not hang the system forever if the boolean variable is not attained.

I have used Thread.Sleep but it stops the await thread from returning a result. I need someone to assist me in finding a solution where the system will wait for the "LoadedShopifyProduct" to be true then continue with the "Button1.click".

*** You will see that the try variable stops once 40 is reached so I really don't know whether the products have been loaded. Is there a better option then Thread.Sleep?

Private Sub TEST
            Show()
            TopMost = True
            Dim HasInternet As Boolean = crm.HaveInternetConnection() :'check if there is internet
            If HasInternet = False Then
                Me.Close()
                Exit sub
            End If
            Form1.LoadShopifyProducts():'calls the Async routine
            Dim trys As Short = 0
            While LoadedShopifyProducts = False And HasInternet = True And trys < 40
                Form1.ToolStripStatusLabel1.Text = "Tries : " & trys & " -> Shopify Products Not loaded ! Please wait a few seconds"
                Application.DoEvents()
                Thread.Sleep(2000)
                trys = trys   1
            End While
            Button1.PerformClick() : 'do next 
End Sub
Public Async Sub LoadShopifyProducts()        
        Dim HasInternet As Boolean = crm.HaveInternetConnection()
        If HasInternet = True Then
            TimesShopifyLoad = TimesShopifyLoad   1
            
            Dim BaseURL = Para(Val(TermNumber), 580)
            Dim Key = Para(Val(TermNumber), 581)

            Dim shopifyClient As New ShopifyApi(BaseURL, Key)
            shopifyClient.Initialise()

            'retrieve all Products from Shopify API
            allShopifyProducts = Await shopifyClient.GetAllProducts()
            'also collate a master list of all Variants from the list of Products returned above to allow searching by SKU which only appears on the variant
            allShopifyVariants = Await shopifyClient.GetAllVariants(allShopifyProducts)
           
           LoadedShopifyProducts = True :' after await set ---> to true ! ! 
            CountShopify = allShopifyVariants.Count
        
            ToolStripStatusLabel1.Text = "( Shopify : " & allShopifyVariants.Count & " ) Times:" & Str(TimesShopifyLoad)
        End If
End Sub

CodePudding user response：

Here's how you would do the basic version of what you want:

Private Async Sub Button1_Click(sender As Object, args As EventArgs)
    If crm.HaveInternetConnection() Then
        Dim variants = Await GetShopifyProducts(Para(Val(TermNumber), 580), Para(Val(TermNumber), 581))
        ' Do something with the variants
    End If
End Sub

Private Async Function GetShopifyProducts(BaseURL As String, Key As String) As Task(Of ShopifyVariant())
    Dim shopifyClient As New ShopifyApi(BaseURL, Key)
    shopifyClient.Initialise()
    Dim products = Await shopifyClient.GetAllProducts()
    Dim variants = Await shopifyClient.GetAllVariants(products)
    Return variants
End Function

If you needed to repeat the call every 2 seconds until a condition is met, then it looks like this:

Private Async Sub Button1_Click(sender As Object, args As EventArgs)
    Me.Timer1.Interval = 2000
    Me.Timer1.Enabled = True
End Sub

Private Async Sub Timer1_Tick(sender As Object, args As EventArgs)
    If crm.HaveInternetConnection() Then
        Dim variants = Await GetShopifyProducts(Para(Val(TermNumber), 580), Para(Val(TermNumber), 581))
        ' Do something with the variants
        If TurnOffTimerCondition Then
            Me.Timer1.Enabled = False
        End If
    End If
End Sub

Private Async Function GetShopifyProducts(BaseURL As String, Key As String) As Task(Of ShopifyVariant())
    Dim shopifyClient As New ShopifyApi(BaseURL, Key)
    shopifyClient.Initialise()
    Dim products = Await shopifyClient.GetAllProducts()
    Dim variants = Await shopifyClient.GetAllVariants(products)
    Return variants
End Function

Update with example timeout:

Private Async Sub Button1_Click(sender As Object, args As EventArgs)
    If Me.Timer1.Enabled = False Then
        Me.Timer1.Interval = 2000
        Me.Timer1.Enabled = True
        sw = Stopwatch.StartNew()
    End If
End Sub

Private Async Sub Timer1_Tick(sender As Object, args As EventArgs)
    If crm.HaveInternetConnection() Then
        Dim variants = Await GetShopifyProducts(Para(Val(TermNumber), 580), Para(Val(TermNumber), 581))
        ' Do something with the variants
        If sw.Elapsed > TimeSpan.FromSeconds(60) Then
            Me.Timer1.Enabled = False
            MessageBox.Show("not met in 60 seconds")
        End If
    End If
End Sub

CodePudding user response：

You can use a background worker and call you function from background workers do work at an event. by using a background worker you can prevent the system from hangup and also can show some progress bars before calling the background worker and hiding on completion.