如何:使用平行工作周遊二進位樹狀
下列範例示範可以使用平行工作來周遊樹狀資料結構的兩種方式。 建立樹狀的部分則留待練習。
範例
public class TreeWalk
{
static void Main()
{
Tree<MyClass> tree = new Tree<MyClass>();
// ...populate tree (left as an exercise)
// Define the Action to perform on each node.
Action<MyClass> myAction = x => Console.WriteLine("{0} : {1}", x.Name, x.Number);
// Traverse the tree with parallel tasks.
DoTree(tree, myAction);
}
public class MyClass
{
public string Name { get; set; }
public int Number { get; set; }
}
public class Tree<T>
{
public Tree<T> Left;
public Tree<T> Right;
public T Data;
}
// By using tasks explicitly.
public static void DoTree<T>(Tree<T> tree, Action<T> action)
{
if (tree == null) return;
var left = Task.Factory.StartNew(() => DoTree(tree.Left, action));
var right = Task.Factory.StartNew(() => DoTree(tree.Right, action));
action(tree.Data);
try
{
Task.WaitAll(left, right);
}
catch (AggregateException )
{
//handle exceptions here
}
}
// By using Parallel.Invoke
public static void DoTree2<T>(Tree<T> tree, Action<T> action)
{
if (tree == null) return;
Parallel.Invoke(
() => DoTree2(tree.Left, action),
() => DoTree2(tree.Right, action),
() => action(tree.Data)
);
}
}
Imports System.Threading.Tasks
Public Class TreeWalk
Shared Sub Main()
Dim tree As Tree(Of Person) = New Tree(Of Person)()
' ...populate tree (left as an exercise)
' Define the Action to perform on each node.
Dim myAction As Action(Of Person) = New Action(Of Person)(Sub(x)
Console.WriteLine("{0} : {1} ", x.Name, x.Number)
End Sub)
' Traverse the tree with parallel tasks.
DoTree(tree, myAction)
End Sub
Public Class Person
Public Name As String
Public Number As Integer
End Class
Public Class Tree(Of T)
Public Left As Tree(Of T)
Public Right As Tree(Of T)
Public Data As T
End Class
' By using tasks explicitly.
Public Shared Sub DoTree(Of T)(ByVal myTree As Tree(Of T), ByVal a As Action(Of T))
If myTree Is Nothing Then
Return
End If
Dim left = Task.Factory.StartNew(Sub() DoTree(myTree.Left, a))
Dim right = Task.Factory.StartNew(Sub() DoTree(myTree.Right, a))
a(myTree.Data)
Try
Task.WaitAll(left, right)
Catch ae As AggregateException
'handle exceptions here
End Try
End Sub
' By using Parallel.Invoke
Public Shared Sub DoTree2(Of T)(ByVal myTree As Tree(Of T), ByVal myAct As Action(Of T))
If myTree Is Nothing Then
Return
End If
Parallel.Invoke(
Sub() DoTree2(myTree.Left, myAct),
Sub() DoTree2(myTree.Right, myAct),
Sub() myAct(myTree.Data)
)
End Sub
End Class
這兩個方法的功能相同。 透過使用 StartNew 方法來建立並執行工作,您會收到來自工作的控制代碼,用於等待工作及處理例外狀況。