1:  Imports System.ComponentModel

   2:   

   3:  Public Class BackgroundWorkerQueue

   4:   

   5:      Public Property ContinueOnError As Boolean

   6:      Private Property Queue As Queue(Of QueuedWorker)

   7:      Private Property DoWorkEventHandler As DoWorkEventHandler

   8:      Public Event QueueFinished()

   9:   

  10:      Public Sub New()

  11:          Me.Queue = New Queue(Of QueuedWorker)()

  12:      End Sub

  13:   

  14:      Public Sub Add(ByVal Worker As BackgroundWorker, ByVal Argument As Object, DoWorkEventHandler1 As DoWorkEventHandler)

  15:          DoWorkEventHandler = DoWorkEventHandler1

  16:          Me.Queue.Enqueue(New QueuedWorker(Worker, Argument))

  17:      End Sub

  18:   

  19:      Public Sub RunWorkerAsync()

  20:          Debug.Print("BackgroundWorker.Run(), {0} items in queue.", Me.Queue.Count)

  21:          Dim Q As QueuedWorker = Me.Queue.Dequeue()

  22:          AddHandler Q.Worker.RunWorkerCompleted, New RunWorkerCompletedEventHandler(AddressOf Me.Completed)

  23:          AddHandler Q.Worker.DoWork, DoWorkEventHandler

  24:          Q.Worker.RunWorkerAsync(Q.Argument)

  25:      End Sub

  26:   

  27:      Private Sub Completed(ByVal sender As Object, ByVal e As RunWorkerCompletedEventArgs)

  28:          Debug.Print("BackgroundWorker.Completed()")

  29:          Dim Worker As BackgroundWorker = TryCast(sender, BackgroundWorker)

  30:          If Worker IsNot Nothing Then

  31:              RemoveHandler Worker.RunWorkerCompleted, AddressOf Me.Completed

  32:              RemoveHandler Worker.DoWork, DoWorkEventHandler

  33:              If (Me.ContinueOnError OrElse e.[Error] Is Nothing) AndAlso Me.Queue.Count > 0 Then

  34:                  Me.RunWorkerAsync()

  35:              ElseIf Queue.Count = 0 Then

  36:                  RaiseEvent QueueFinished()

  37:              End If

  38:          End If

  39:      End Sub

  40:  End Class

  41:   

  42:  Public Class QueuedWorker

  43:      Public Property Argument As Object

  44:      Public Property Worker As BackgroundWorker

  45:   

  46:      Public Sub New()

  47:      End Sub

  48:   

  49:      Public Sub New(ByVal Worker1 As BackgroundWorker, ByVal Argument1 As Object)

  50:          Worker = Worker1

  51:          Argument = Argument1

  52:      End Sub

  53:  End Class

 ...    

 306:                  Dim BGWorkerQueue As New BackgroundWorkerQueue

 307:                  AddHandler BGWorkerQueue.QueueFinished, AddressOf BGWorkerQueueFinished

 308:                  Dim BGW3 As New BackgroundWorker

 309:                  For Each Link In LinkCollections

 ...    

 311:                      BGWorkerQueue.Add(BGW3, URL, AddressOf BGW3_DoWork)

 312:                  Next

 313:                  BGWorkerQueue.RunWorkerAsync()

 314:              End If

 315:          End If

 316:      End Sub

 317:   

 319:      Private Sub BGW3_DoWork(sender As Object, e As DoWorkEventArgs)

 ...    

 327:              Download(e.Argument, ...)

 ...    

 330:      End Sub

 ...:   

 342:      Sub BGWorkerQueueFinished()

 ...    

 353:      End Sub

 354: