Question

I would like to start a background task without using the Await keyword. Instead I want to monitor the task at various points and restart it when necessary to update information in the background. Here is the method I am trying to call:

    Public Async Function UpdateVehicleSummaries(p_vehicleID As Int32) As Task(Of Boolean)
        Dim tempVehicle As Koolsoft.MARS.BusinessObjects.Vehicle
        For Each tempVehicle In Vehicles
            If p_vehicleID = 0 Or p_vehicleID = tempVehicle.VehicleID Then
                Await UpdateVehicleStats(tempVehicle)
            End If
        Next

        Return True
    End Function

The code I am trying to start the task doesn’t seem to work and I’m not sure how to provide the parameter. I get an error that “Task(Of Boolean) cannot be converted to System.Action and or an error on the parameter”

    Dim tempTask As Task
    tempTask = New Task(UpdateVehicleSummaries(tempVehicleID))
    tempTask.Start()

Any help would be appreciated.

Answer 1

Since UpdateVehicleSummaries is already asynchronous, you should be abel to just do:

Dim tempTask As Task(Of Boolean) = UpdateVehicleSummaries(tempVehicleID)

The returned Task(Of T) will be “hot” (running), but shouldn’t block, as the Await call will immediately return control flow to the caller at that point.

---

A more typical use of this method, if you need to perform other work while this runs, would be to do the following:

Dim tempTask = UpdateVehicleSummaries(tempVehicleID)

' Do your other work

Dim success = Await tempTask ' Get the boolean result asynchronously...

' use the result