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'<snippet01>
Imports System
Imports System.Collections.Generic
Imports System.Linq
Imports System.Text
Imports System.Threading
Imports System.Threading.Tasks
Class Program
Shared words1() = New String() {"brown", "jumped", "the", "fox", "quick"}
Shared words2() = New String() {"dog", "lazy", "the", "over"}
Shared solution = "the quick brown fox jumped over the lazy dog."
Shared success = False
Shared barrier = New Barrier(2, Sub(b)
Dim sb = New StringBuilder()
For i As Integer = 0 To words1.Length - 1
sb.Append(words1(i))
sb.Append(" ")
Next
For i As Integer = 0 To words2.Length - 1
sb.Append(words2(i))
If (i < words2.Length - 1) Then
sb.Append(" ")
End If
Next
sb.Append(".")
System.Diagnostics.Trace.WriteLine(sb.ToString())
Console.CursorLeft = 0
Console.Write("Current phase: {0}", barrier.CurrentPhaseNumber)
If (String.CompareOrdinal(solution, sb.ToString()) = 0) Then
success = True
Console.WriteLine()
Console.WriteLine("The solution was found in {0} attempts", barrier.CurrentPhaseNumber)
End If
End Sub)
Shared Sub Main()
Dim t1 = New Thread(Sub() Solve(words1))
Dim t2 = New Thread(Sub() Solve(words2))
t1.Start()
t2.Start()
' Keep the console window open.
Console.ReadLine()
End Sub
' Use Knuth-Fisher-Yates shuffle to randomly reorder each array.
' For simplicity, we require that both wordArrays be solved in the same phase.
' Success of right or left side only is not stored and does not count.
Shared Sub Solve(ByVal wordArray As String())
While success = False
Dim rand = New Random()
For i As Integer = 0 To wordArray.Length - 1
Dim swapIndex As Integer = rand.Next(i + 1)
Dim temp As String = wordArray(i)
wordArray(i) = wordArray(swapIndex)
wordArray(swapIndex) = temp
Next
' We need to stop here to examine results
' of all thread activity. This is done in the post-phase
' delegate that is defined in the Barrier constructor.
barrier.SignalAndWait()
End While
End Sub
End Class
'</snippet01>
Class BarrierDemo
Friend success As Boolean
Friend someCondition As Boolean
Dim results() As Byte
Dim myData()() As Byte
Function ProcessData(ByVal d As Byte())
Return New Byte()
End Function
'<snippet02>
' Create the Barrier object, and supply a post-phase delegate
' to be invoked at the end of each phase.
Dim barrier = New Barrier(2, Sub(bar)
' Examine results from all threads, determine
' whether to continue, create inputs for next phase, etc.
If (someCondition) Then
success = True
End If
End Sub)
' Define the work that each thread will perform. (Threads do not
' have to all execute the same method.)
Sub CrunchNumbers(ByVal partitionNum As Integer)
' Up to System.Int64.MaxValue phases are supported. We assume
' in this code that the problem will be solved before that.
While (success = False)
' Begin phase:
' Process data here on each thread, and optionally
' store results, for example:
results(partitionNum) = ProcessData(myData(partitionNum))
' End phase:
' After all threads arrive,post-phase delegate
' is invoked, then threads are unblocked. Overloads
' accept a timeout value and/or CancellationToken.
barrier.SignalAndWait()
End While
End Sub
' Perform n tasks to run in in parallel. For simplicity
' all threads execute the same method in this example.
Shared Sub Main()
Dim app = New BarrierDemo()
Dim t1 = New Thread(Sub() app.CrunchNumbers(0))
Dim t2 = New Thread(Sub() app.CrunchNumbers(1))
t1.Start()
t2.Start()
End Sub
'</snippet02>
End Class