using System;

using System.Linq;

using System.Collections.Generic;

using System.Threading.Tasks;

using System.Threading.Tasks.Dataflow;

public class Program

{

    public static async Task Main()

    {

        var computer = new ComplicatedComputation(10);

        Console.WriteLine("Result={0}", await computer.ComputeAsync());

    }

}

​

public class ComplicatedComputation

{

    private readonly int _input;

    private double _result = 0;

    private ITargetBlock<int> _startBlock;

    private IDataflowBlock _endBlock;

    public ComplicatedComputation(int input)

    {

        _input = input;

        var fanOutBlock = new TransformManyBlock<int, int>(x =>

        {

           return Enumerable.Range(1, x).Select(x => x);

        });

​

        var squareBlock = new TransformBlock<int, int>(async x =>

        {

            return x * x;

        }, new ExecutionDataflowBlockOptions { MaxDegreeOfParallelism = 5 });

​

        var addFiveBlock = new TransformBlock<int, int>(x =>

        {

           return x + 5;

        }, new ExecutionDataflowBlockOptions { MaxDegreeOfParallelism = 5 });

​

        var divTwoBlock = new TransformBlock<int, double>(x =>

        {

            return x/2.0;

        }, new ExecutionDataflowBlockOptions { MaxDegreeOfParallelism = 5 });

​

        var sumBlock = new ActionBlock<double>(x =>

        {

            _result += x;

        });

​

        var options = new DataflowLinkOptions { PropagateCompletion = true };

​

        fanOutBlock.LinkTo(squareBlock, options);

        squareBlock.LinkTo(addFiveBlock, options);

        addFiveBlock.LinkTo(divTwoBlock, options);

        divTwoBlock.LinkTo(sumBlock, options);

        _startBlock = fanOutBlock;

        _endBlock = sumBlock;

    }

    public async Task<double> ComputeAsync()

    {

        _startBlock.Post(_input);

        _startBlock.Complete();

        await _endBlock.Completion;

        return _result;

    }

}