ActionBlock<TInput> Class

Definition

Namespace:

System.Threading.Tasks.Dataflow

Assembly:

System.Threading.Tasks.Dataflow.dll

Source:

ActionBlock.cs

Provides a dataflow block that invokes a provided Action<T> delegate for every data element received.

generic <typename TInput>
public ref class ActionBlock sealed : System::Threading::Tasks::Dataflow::ITargetBlock<TInput>

public sealed class ActionBlock<TInput> : System.Threading.Tasks.Dataflow.ITargetBlock<TInput>

type ActionBlock<'Input> = class
    interface IDataflowBlock
    interface ITargetBlock<'Input>

Public NotInheritable Class ActionBlock(Of TInput)
Implements ITargetBlock(Of TInput)

Type Parameters

TInput

The type of data that this ActionBlock<TInput> operates on.

Inheritance

Object

ActionBlock<TInput>

Implements

IDataflowBlock ITargetBlock<TInput>

Examples

The following example shows the use of the ActionBlock<TInput> class to perform several computations using dataflow blocks, and returns the elapsed time required to perform the computations. This code example is part of a larger example provided for the How to: Specify the Degree of Parallelism in a Dataflow Block article.

// 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

Remarks

Note

The TPL Dataflow Library (the System.Threading.Tasks.Dataflow namespace) is not distributed with .NET. To install the System.Threading.Tasks.Dataflow namespace in Visual Studio, open your project, choose Manage NuGet Packages from the Project menu, and search online for the System.Threading.Tasks.Dataflow package. Alternatively, to install it using the .NET Core CLI, run dotnet add package System.Threading.Tasks.Dataflow.

Constructors

ActionBlock<TInput>(Action<TInput>)	Initializes a new instance of the ActionBlock<TInput> class with the specified action.
ActionBlock<TInput>(Action<TInput>, ExecutionDataflowBlockOptions)	Initializes a new instance of the ActionBlock<TInput> class with the specified action and configuration options.
ActionBlock<TInput>(Func<TInput,Task>)	Initializes a new instance of the ActionBlock<TInput> class with the specified action.
ActionBlock<TInput>(Func<TInput,Task>, ExecutionDataflowBlockOptions)	Initializes a new instance of the ActionBlock<TInput> class with the specified action and configuration options.

Properties

Completion	Gets a Task object that represents the asynchronous operation and completion of the dataflow block.
InputCount	Gets the number of input items waiting to be processed by this block.

Methods

Complete()	Signals to the dataflow block that it shouldn't accept or produce any more messages and shouldn't consume any more postponed messages.
Equals(Object)	Determines whether the specified object is equal to the current object. (Inherited from Object)
GetHashCode()	Serves as the default hash function. (Inherited from Object)
GetType()	Gets the Type of the current instance. (Inherited from Object)
MemberwiseClone()	Creates a shallow copy of the current Object. (Inherited from Object)
Post(TInput)	Posts an item to the target dataflow block.
ToString()	Returns a string that represents the formatted name of this IDataflowBlock instance.

Explicit Interface Implementations

IDataflowBlock.Fault(Exception)	Causes the dataflow block to complete in a faulted state.
ITargetBlock<TInput>.OfferMessage(DataflowMessageHeader, TInput, ISourceBlock<TInput>, Boolean)	Offers a message to the dataflow block, and gives it the opportunity to consume or postpone the message.

Extension Methods

AsObserver<TInput>(ITargetBlock<TInput>)	Creates a new IObserver<T> abstraction over the ITargetBlock<TInput>.
Post<TInput>(ITargetBlock<TInput>, TInput)	Posts an item to the ITargetBlock<TInput>.
SendAsync<TInput>(ITargetBlock<TInput>, TInput)	Asynchronously offers a message to the target message block, allowing for postponement.
SendAsync<TInput>(ITargetBlock<TInput>, TInput, CancellationToken)	Asynchronously offers a message to the target message block, allowing for postponement.