ActionBlock<TInput>.Completion 属性

定义

命名空间:

System.Threading.Tasks.Dataflow

程序集:

System.Threading.Tasks.Dataflow.dll

Source:

ActionBlock.cs

获取一个 Task 对象，该对象表示数据流块的异步操作和完成。

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

属性值

Task

已完成任务。

实现

Completion

示例

以下示例演示如何使用 Completion 属性等待所有消息通过网络传播。 此代码示例是针对 如何：在数据流块中指定并行度 主题提供的更大示例的一部分。

// 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

注解

如果数据流块当前未处理消息，并且已保证不再处理消息，则数据流块被视为已完成。 当关联的块完成时，返回 Task 的 将转换为已完成状态。 当块根据数据流块定义的语义成功完成其处理时，它将转换为 RanToCompletion 状态。 当数据流块由于未经处理的异常而提前完成处理时，它将转换到 Faulted 状态;当数据流块在收到取消请求后提前完成处理时，它将转换到 Canceled 状态。 如果任务在 状态中 Faulted 完成，其 Exception 属性将返回一个 AggregateException 异常，其中包含导致块失败的一个或多个异常。