ActionBlock<TInput>.Completion 屬性

定義

命名空間:

System.Threading.Tasks.Dataflow

組件:

System.Threading.Tasks.Dataflow.dll

取得 Task 物件，表示非同步作業和資料流程區塊的完成。

public:
 property System::Threading::Tasks::Task ^ Completion { System::Threading::Tasks::Task ^ get(); };

public System.Threading.Tasks.Task Completion { get; }

member this.Completion : System.Threading.Tasks.Task

Public ReadOnly Property Completion As Task

屬性值

Task

已完成的工作。

實作

Completion

範例

下列範例示範如何使用 Completion 屬性來等候所有訊息透過網路傳播。 此程式碼範例是 如何：在資料流程區塊主題中指定平行處理原則程度 之較大範例的一部分。

// Performs several computations by using dataflow and returns the elapsed
// time required to perform the computations.
static TimeSpan TimeDataflowComputations(int maxDegreeOfParallelism,
   int messageCount)
{
   // Create an ActionBlock<int> that performs some work.
   var workerBlock = new ActionBlock<int>(
      // Simulate work by suspending the current thread.
      millisecondsTimeout => Thread.Sleep(millisecondsTimeout),
      // Specify a maximum degree of parallelism.
      new ExecutionDataflowBlockOptions
      {
         MaxDegreeOfParallelism = maxDegreeOfParallelism
      });

   // Compute the time that it takes for several messages to
   // flow through the dataflow block.

   Stopwatch stopwatch = new Stopwatch();
   stopwatch.Start();

   for (int i = 0; i < messageCount; i++)
   {
      workerBlock.Post(1000);
   }
   workerBlock.Complete();

   // Wait for all messages to propagate through the network.
   workerBlock.Completion.Wait();

   // Stop the timer and return the elapsed number of milliseconds.
   stopwatch.Stop();
   return stopwatch.Elapsed;
}

' Demonstrates how to specify the maximum degree of parallelism 
' when using dataflow.
Friend Class Program
   ' Performs several computations by using dataflow and returns the elapsed
   ' time required to perform the computations.
   Private Shared Function TimeDataflowComputations(ByVal maxDegreeOfParallelism As Integer, ByVal messageCount As Integer) As TimeSpan
      ' Create an ActionBlock<int> that performs some work.
      Dim workerBlock = New ActionBlock(Of Integer)(Function(millisecondsTimeout) Pause(millisecondsTimeout), New ExecutionDataflowBlockOptions() With { .MaxDegreeOfParallelism = maxDegreeOfParallelism})
         ' Simulate work by suspending the current thread.
         ' Specify a maximum degree of parallelism.

      ' Compute the time that it takes for several messages to 
      ' flow through the dataflow block.

      Dim stopwatch As New Stopwatch()
      stopwatch.Start()

      For i As Integer = 0 To messageCount - 1
         workerBlock.Post(1000)
      Next i
      workerBlock.Complete()

      ' Wait for all messages to propagate through the network.
      workerBlock.Completion.Wait()

      ' Stop the timer and return the elapsed number of milliseconds.
      stopwatch.Stop()
      Return stopwatch.Elapsed
   End Function

   Private Shared Function Pause(ByVal obj As Object)
      Thread.Sleep(obj)
      Return Nothing
   End Function

備註

資料流程區塊在目前未處理訊息時視為已完成，且當資料流程區塊保證不會再處理任何訊息時。 當相關聯的區塊完成時，傳回的 Task 會轉換為已完成的狀態。 當區塊根據資料流程區塊定義的語意順利完成處理時，它會轉換為 RanToCompletion 狀態。 當資料流程區塊因為未處理的例外狀況而提前完成處理時，它會轉換成 Faulted Canceled 狀態，而資料流程區塊在收到取消要求之後，會提前完成處理。 如果工作在 狀態中 Faulted 完成，其 Exception 屬性會 AggregateException 傳回例外狀況，其中包含導致區塊失敗的一或多個例外狀況。