将基于C# BlockingCollection的代码转换为TPL数据流

Question

我有一个具体的问题，相信可以用TPL数据流解决。我刚接触这个，所以需要你的帮助来加快我的理解。目前我的代码是这样的：

其中Process1、Process2、Process3都是任务。使用阻塞集合将对象从一个块传递到另一个块。我想这样做：

我读到了TransformBlock、ActionBlock和BatchBlock的相关内容。您能帮助我如何使用这些类来实现上述设计吗？

- Subhash Makkena

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请勿以图像形式发布代码。 - VMAtm

相关：TPL Dataflow，JoinBlock限制的替代方案？ - Theodor Zoulias

Answer 1

您没有提供关于Process2和Process3块如何处理输入数据的详细信息，因此我假设它们中的每一个都对原始对象进行了某些独特的转换，以便输出对象列表包含两个过程的合并结果。

using System;
using System.Threading.Tasks;
using System.Threading.Tasks.Dataflow;

namespace TPLDataFlowExample1
{
    class Program
    {
        static void Main(string[] args)
        {
            var inputListOfObjects = new int[] { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };

            // Process1 block
            var process1 = new TransformBlock<int, int>(i => i * 2);
            // Broadcast block which passes objects to Process2 and Process3
            var broadCast = new BroadcastBlock<int>(null);
            // Process2 block
            var process2 = new TransformBlock<int, string>(i => $"Process 2: {i}");
            // Process3 block
            var process3 = new TransformBlock<int, string>(i => $"Process 3: {i}");
            // Just simple action block which will print the result
            var print = new ActionBlock<string>(s => Console.WriteLine(s));

            // Link the output of Process1 block with the input of Broadcast block. Propagate completion to the next block.
            process1.LinkTo(broadCast, new DataflowLinkOptions { PropagateCompletion = true });
            // Link the output of Broadcast block with the input of Process2 block. Propagate completion to the next block.
            broadCast.LinkTo(process2, new DataflowLinkOptions { PropagateCompletion = true });
            // Link the output of Broadcast block with the input of Process3 block. Propagate completion to the next block.
            broadCast.LinkTo(process3, new DataflowLinkOptions { PropagateCompletion = true });
            // Link the output of Process2 block with the input of Print block. 
            process2.LinkTo(print);
            // Link the output of Process2 block with the input of print block. 
            process3.LinkTo(print);

            // We didn't propagate completion to Print block because it must complete when both Process2 and Process3 blocks are in Completed state.
            Task.WhenAll(process2.Completion, process3.Completion).ContinueWith(_ => print.Complete());

            // Post data to the Process1 block
            foreach (var obj in inputListOfObjects)
            {
                process1.Post(obj);
            }

            // Mark the Process1 block as complete
            process1.Complete();
            // Wait for the last block to process all messages
            print.Completion.Wait();
        }
    }
}


// Output:
//
// Process 2: 2
// Process 3: 2
// Process 3: 4
// Process 3: 6
// Process 3: 8
// Process 3: 10
// Process 3: 12
// Process 3: 14
// Process 3: 16
// Process 3: 18
// Process 3: 20
// Process 2: 4
// Process 2: 6
// Process 2: 8
// Process 2: 10
// Process 2: 12
// Process 2: 14
// Process 2: 16
// Process 2: 18
// Process 2: 20
// Press any key to continue . . .

- Alexey Andrushkevich