async/await on many forms ping function - vb.net

Question

I have some problem and couldn't see so far what i am doing wrong. My application user can open some form multiple times and within each of it i want to make ping time to time to some remote host then show status on status bar, therefore to not block main thread and ui i decided to go asyn/await. Unfortunetly within 'DoWork' method 'StartNew' is highlited within this line:
Await Task.Factory.StartNew(IsDestinationReachable(IPAddress))
Severity Code Description Project File Line Suppression State
Error BC36645 Data type(s) of the type parameter(s) in method 'Public
Overloads Function StartNew(Of TResult)([function] As Func(Of
TResult)) As Task(Of TResult)' cannot be inferred from these
arguments. Specifying the data type(s) explicitly might correct this
error.
And by the way is it right way i am doing it? Check my code below:
Public Class FrmDrukujEtykiete
Private Property IPAddress As String
Private WithEvents mytimer As Timer
Sub New(ipaddress As String)
InitializeComponent()
AddHandler mytimer.Tick, AddressOf dowork
mytimer.Interval = 6000
mytimer.Enabled = True
mytimer.Start()
Me.IPAddress = ipaddress
End Sub
Public Async Sub dowork(sender As Object, e As EventArgs)
Dim MMOO As Task(Of Boolean) = Await Task.Factory.StartNew(IsDestinationReachable(IPAddress))
If MMOO.Result Then
tsPingResultIcon.BackColor = Color.Green
tsPingResultIcon.Text = "OK - Remote ip reachable"
Else
tsPingResultIcon.BackColor = Color.Red
tsPingResultIcon.Text = "NOT OK - Remote ip NOT reachable"
End If
End Sub
Public Function IsDestinationReachable(ByVal hostnameOrAddress As String) As Boolean
Dim reachable As Boolean = False
Try
reachable = My.Computer.Network.IsAvailable AndAlso My.Computer.Network.Ping(hostnameOrAddress)
Catch pingException As System.Net.NetworkInformation.PingException
Catch genericNetworkException As System.Net.NetworkInformation.NetworkInformationException
' Fail silently and return false
End Try
Return reachable
End Function
End Class
EDIT:
i think i was able to make it happen - one thing which still considering me is why when user opening new form before it show up its about 4 seconds... second thing is it correct - i mean can you check my code is there any wrong task conception usage? Generally working...
Public Class FrmDrukujEtykiete
Private etykieta As New Etykieta
Private Property IPAddress As String
Private WithEvents mytimer As New Timer
Sub New(ipaddress As String)
InitializeComponent()
Me.IPAddress = ipaddress
AddHandler mytimer.Tick, AddressOf dowork
mytimer.Interval = 6000
mytimer.Enabled = True
mytimer.Start()
DoSomethingElse()
End Sub
Private Sub DoSomethingElse()
For i = 1 To 100000
' Threading.Thread.Sleep(1000)
ListBox1.Items.Add(i)
Next
End Sub
Private Sub btnWyjdz_Click(sender As Object, e As EventArgs) Handles btnWyjdz.Click
Close()
End Sub
Public Async Sub dowork(sender As Object, e As EventArgs)
Dim tsk As Task(Of Boolean) = Task.Factory.StartNew(Of Boolean)(Function()
'--Run lenghty task
Dim reachable = False
Try
reachable = My.Computer.Network.IsAvailable AndAlso My.Computer.Network.Ping(IPAddress)
Catch pingException As System.Net.NetworkInformation.PingException
Catch genericNetworkException As System.Net.NetworkInformation.NetworkInformationException
' Fail silently and return false
End Try
Return reachable
End Function)
Await tsk
ListBox2.Items.Add("a teraz zmiana")
If tsk.Result Then
tsPingResultIcon.BackColor = Color.Green
tsPingResultIcon.Text = "OK - Remote ip reachable"
Else
tsPingResultIcon.BackColor = Color.Red
tsPingResultIcon.Text = "NOT OK - Remote ip NOT reachable"
End If
End Sub
Public Function IsDestinationReachable(ByVal hostnameOrAddress As String)
Dim reachable = False
Try
reachable = My.Computer.Network.IsAvailable AndAlso My.Computer.Network.Ping(hostnameOrAddress)
Catch pingException As System.Net.NetworkInformation.PingException
Catch genericNetworkException As System.Net.NetworkInformation.NetworkInformationException
' Fail silently and return false
End Try
Return reachable
End Function
End Class

Answer 1

Your updated code is not typically how you would use Async/Await. More usual would be something like:
Public Async Sub dowork(sender As Object, e As EventArgs)
Dim isReachable As Boolean = Await Task.Factory.StartNew(Function() IsDestinationReachable(IPAddress))
If isReachable Then
tsPingResultIcon.BackColor = Color.Green
tsPingResultIcon.Text = "OK - Remote ip reachable"
Else
tsPingResultIcon.BackColor = Color.Red
tsPingResultIcon.Text = "NOT OK - Remote ip NOT reachable"
End If
End Sub
The Await suspends the method until the task completes and then returns the result of the task, so there is no need to hold onto the Task object and use .Result. While the method is suspended, execution of the non-Awaiting code continues on the main thread, and the method is resumed on the main thread when the async method completes.
However, since network IO is naturally async, you would be better off using the Ping.SendPingAsync method instead of Task.Factory.StartNew. That would be something like this (untested code):
Public Async Sub dowork(sender As Object, e As EventArgs)
Dim isReachable As Boolean = Await IsDestinationReachable(IPAddress)
If isReachable Then
tsPingResultIcon.BackColor = Color.Green
tsPingResultIcon.Text = "OK - Remote ip reachable"
Else
tsPingResultIcon.BackColor = Color.Red
tsPingResultIcon.Text = "NOT OK - Remote ip NOT reachable"
End If
End Sub
Public Async Function IsDestinationReachable(ByVal hostnameOrAddress As String) As Boolean
Dim reachable As Boolean = False
Try
If My.Computer.Network.IsAvailable Then
Dim pinger As Ping = New Ping()
Dim result As PingReply = Await pinger.SendPingAsync(hostnameOrAddress)
reachable = result.Status = IPStatus.Success
End If
Catch pingException As System.Net.NetworkInformation.PingException
Catch genericNetworkException As System.Net.NetworkInformation.NetworkInformationException
' Fail silently and return false
End Try
Return reachable
End Function