TPL Dataflow Transform block post to batch block followed by actionblock

问题

I have a TPL Dataflow based application, that worked fine using only a batch block, then an action block.

I've added in a TransformBlock to try and trasnform the data from the source before posting to the batch block, but my action block is never getting hit. There are no errors or exceptions being thrown.

I am unsure if I need to complete my transform block, as it only seems to be being hit once.

Is there a step that I need to add to my transform code other than returning an object of the output type?

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Threading.Tasks.Dataflow;

namespace DataflowTest
{
    class Program
    {
        public const int BATCH_SIZE = 10;
        static void Main(string[] args)
        {
            Console.WriteLine("Application started");

            //Create the pipeline of actions
            var transformBlock = new TransformBlock<string, string>(input => TransformString(input), new ExecutionDataflowBlockOptions { MaxDegreeOfParallelism = 1 });
            var batchBlock = new BatchBlock<string>(BATCH_SIZE);
            var uploadFilesToAzureBlock = new ActionBlock<IEnumerable<string>>(strings => OutputStrings(strings), new ExecutionDataflowBlockOptions { MaxDegreeOfParallelism = 1 });

            Console.WriteLine("Blocks created");

            //link the actions
            transformBlock.LinkTo(batchBlock);
            batchBlock.LinkTo(uploadFilesToAzureBlock);
            batchBlock.Completion.ContinueWith(obj => uploadFilesToAzureBlock.Complete());

            Console.WriteLine("Blocks linked");

            var testInputs = new List<string>
            {
                "Kyle",
                "Stephen",
                "Jon",
                "Conor",
                "Adrian",
                "Marty",
                "Richard",
                "Norbert",
                "Kerri",
                "Mark",
                "Declan",
                "Ray",
                "Paul",
                "Andrew",
                "Rachel",
                "David",
                "Darrell"
            };

            Console.WriteLine("Data created");

            var i = 0;
            foreach (var name in testInputs)
            {
                Console.WriteLine("Posting name {0}", i);
                transformBlock.Post(name);
                i++;
            }

            batchBlock.Complete();
            uploadFilesToAzureBlock.Completion.Wait();

            Console.WriteLine("Finishing");
            Console.ReadKey();
        }

        private static void OutputStrings(IEnumerable<string> strings)
        {
            Console.WriteLine("Beginning Batch...");

            foreach (var s in strings)
            {
                Console.WriteLine(s);
            }

            Console.WriteLine("Completing Batch...");
        }

        private static string TransformString(string input)
        {
            return input += " has been processed";
        }
    }
}

回答1:

As mentioned by "usr" above, I had not propagated the completion of the blocks. The following code works perfectly.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Threading.Tasks.Dataflow;

namespace DataflowTest
{
    class Program
    {
        public const int BATCH_SIZE = 10;
        static void Main(string[] args)
        {
            Console.WriteLine("Application started");

            //Create the pipeline of actions
            var transformBlock = new TransformBlock<string, string>(input => TransformString(input), new ExecutionDataflowBlockOptions { MaxDegreeOfParallelism = 2 });
            var batchBlock = new BatchBlock<string>(BATCH_SIZE);
            var outputStringsBlock = new ActionBlock<IEnumerable<string>>(strings => OutputStrings(strings), new ExecutionDataflowBlockOptions { MaxDegreeOfParallelism = 2 });

            Console.WriteLine("Blocks created");

            //link the actions
            transformBlock.LinkTo(batchBlock, new DataflowLinkOptions { PropagateCompletion = true });
            batchBlock.LinkTo(outputStringsBlock, new DataflowLinkOptions { PropagateCompletion = true });
            batchBlock.Completion.ContinueWith(obj => outputStringsBlock.Complete());

            Console.WriteLine("Blocks linked");

            var testInputs = new List<string>
            {
                "Kyle",
                "Stephen",
                "Jon",
                "Conor",
                "Adrian",
                "Marty",
                "Richard",
                "Norbert",
                "Kerri",
                "Mark",
                "Declan",
                "Ray",
                "Paul",
                "Andrew",
                "Rachel",
                "David",
                "Darrell"
            };

            Console.WriteLine("Data created");

            var i = 0;
            foreach (var name in testInputs)
            {
                Console.WriteLine("Posting name {0}", i);
                transformBlock.Post(name);
                i++;
            }

            transformBlock.Complete();
            outputStringsBlock.Completion.Wait();

            Console.WriteLine("Finishing");
            Console.ReadKey();
        }

        private static void OutputStrings(IEnumerable<string> strings)
        {
            Console.WriteLine("Beginning Batch...");
            Console.WriteLine("");

            foreach (var s in strings)
            {
                Console.WriteLine(s);
            }

            Console.WriteLine("");
            Console.WriteLine("Completing Batch...");
        }

        private static string TransformString(string input)
        {
            return input += " has been processed";
        }
    }
}

来源：https://stackoverflow.com/questions/31804794/tpl-dataflow-transform-block-post-to-batch-block-followed-by-actionblock