Creating async selects to WMI and wait to their co

Question

I read a lot of posts about async methods, but still... I'm a little confused about this. So maybe someone can help me with my case. Right now my code doesn't throw any error, but I know that my code is not good, cause I use async void and I can't wait for all my task to be completed.

So, can someone please help me edit this code:

In my form class, I create Relation:

Relation rel = new Relation(cb_MachineToConnect.Text);

In Relation class:

public Relation(string machineAddress)
    {
        isAsctive = true;
        idCount++;
        relationID = idCount;

        machine = new Machine(machineAddress);
        //I'm using WMI for gettig data from remote machine
        scope = new ManagementScope(string.Format("\\\\{0}\\root\\cimv2", machineAddress));
        scope.Options.Timeout = TimeSpan.FromSeconds(timeOut);

        //In this method, I need run async part of code - WMI selects
        LoadMachineData();
    }

LoadMachineData methode code:

    private async void LoadMachineData()
    {
        try
        {
            scope.Connect();

            try
            {
                //List<Task> taskList = new List<Task>();
                foreach (KeyValuePair<SelectQueryName, SelectQuery> select in SelectQueryes)
                {
                    //And this is it.. I need to run this methods async for better performance. SelectFromWMI is in Relation class and SetWMIproiperties is in Machine class
                    await Task.Run(() => machine.SetWMIProperties(select.Key, SelectFromWMI(select.Value, scope)));
                    //taskList.Add(t);
                    //machine.SetWMIProperties(select.Key, SelectFromWMI(select.Value, scope));
                }
                //I also want to wait for all created Tasks completion, but with this code it is not possible
                //Task.WaitAll(taskList.ToArray());
            }
            catch (Exception ex)
            {
                EventNotifier.LogOnScreen(string.Format("{0}, viz: {1}", ErrorList.GetEIbyID(15).definition, ex.Message));
                EventNotifier.Log(ex, ErrorList.GetEIbyID(15));
            }
        }
        catch (Exception ex)
        {
            EventNotifier.LogOnScreen(string.Format("{0}, viz: {1}", ErrorList.GetEIbyID(16).definition, ex.Message));
            EventNotifier.Log(ex, ErrorList.GetEIbyID(17));
        }
    }

SetWMIProperties(...) in Machine class:

    public void SetWMIProperties(SelectQueryName queryName, List<Dictionary<string, string>> propertiesData)
    {
        foreach (Dictionary<string, string> result in propertiesData)
        {
            switch (queryName)
            {
                case SelectQueryName.DiskModel:

                    disks.Add(result["Model"]);
                    break;

                case SelectQueryName.Drives:

                    drives.Add(new Drive { Name = result["Name"], FreeSpace = Convert.ToInt64(result["FreeSpace"]), Size = Convert.ToInt64(result["Size"]) });
                    break;

                case SelectQueryName.OS:

                    operatingSystem = new OS { BuildNumber = result["BuildNumber"], ProductName = result["Caption"], BitVersion = (result["OSArchitecture"].Contains(((int)OSBitVersion.Win32).ToString())) ? OSBitVersion.Win32 : OSBitVersion.Win64 };
                    break;

                case SelectQueryName.Processor:

                    processor = result["Name"];
                    break;

                case SelectQueryName.RAM:

                    ram = new RAM { TotalVisibleMemorySize = Convert.ToInt64(result["TotalVisibleMemorySize"]), FreePhysicalMemory = Convert.ToInt64(result["FreePhysicalMemory"]) };
                    break;
            }
        }
    }

And the WMI select method in Relation class (in fact, this method should to be truly async, cause WMI select can sometimes be really slow):

    private static List<Dictionary<string, string>> SelectFromWMI(SelectQuery select, ManagementScope wmiScope)
    {
        List<Dictionary<string, string>> result = new List<Dictionary<string, string>>();

        ManagementObjectSearcher searcher = new ManagementObjectSearcher(wmiScope, select);
        ManagementObjectCollection objectCollection = searcher.Get();

        foreach (ManagementObject managementObject in objectCollection)
        {
            result.Add(new Dictionary<string, string>());
            foreach (PropertyData property in managementObject.Properties)
            {
                result.Last().Add(property.Name, property.Value.ToString());
            }
        }

        return result;
    }

Answer 1

To await all your tasks you can use Task.WhenAll():

private async void LoadMachineData()
{
    try
    {
        scope.Connect();

        try
        {
            var tasks = new List<Task>();
            foreach (KeyValuePair<SelectQueryName, SelectQuery> select in SelectQueryes)
            {
                tasks.Add(Task.Run(() => machine.SetWMIProperties(select.Key, SelectFromWMI(select.Value, scope))));
            }

            await Task.WhenAll(tasks);
        }
        catch (Exception ex)
        {
            EventNotifier.LogOnScreen(string.Format("{0}, viz: {1}", ErrorList.GetEIbyID(15).definition, ex.Message));
            EventNotifier.Log(ex, ErrorList.GetEIbyID(15));
        }
    }
    catch (Exception ex)
    {
        EventNotifier.LogOnScreen(string.Format("{0}, viz: {1}", ErrorList.GetEIbyID(16).definition, ex.Message));
        EventNotifier.Log(ex, ErrorList.GetEIbyID(17));
    }
}

To wait for completion of LoadMachineData() you can change it signature to async Task and call as LoadMachineData().Wait(). Is that what you need?