Question

我有一个mvc5控制器，它消耗两个分页的远程数据服务。必须串联调用这两个服务 - 当从serviceA返回一页数据时，必须将其发送到serviceB。我的完全连续实现看起来像这样：

var pageNumber = 1;
var totalPages = x;
var results = new List<ProcessedResult>();
do {
    // Get results from service A.
    var initialResults = await serviceA.GetDataPageAsync(pageNumber);

    // Send serviceA's results to service B
    var processedResults = await serviceB.ProcessAsync(initialResults );

    // Save this iteration's results to our result collection.
    results.AddRange(processedResults); 

    //Report our progress so far
    ReportProgress((float)(pageNumber/totalPages)*100);

} while (pageNumber<totalPages);

return View(results)

如何在不中断延续（serviceB跟随每个页面的serviceA）或进度报告的情况下，如何并行（或异步）查询“页面”？感谢。

Answer 1

您可以使用TPL Dataflow。您可以使用其操作和选项（例如MaxDegreeOfParallelism）创建每个块，并使用LinkTo将它们连接在一起：

var aBlock = new TrasnformBlock<int, InitalResult>(
    pageNumber =>  serviceA.GetDataPageAsync(pageNumber),
    new ExecutionDataflowBlockOptions { MaxDegreeOfParallelism = 5});
var bBlock = new TrasnformBlock<InitalResult, ProcessedResult>(async initialResult =>  
{
    var result = await serviceB.ProcessAsync(initialResult);
    // ReportProgress
    return result;
}, new ExecutionDataflowBlockOptions { MaxDegreeOfParallelism = 5});   

aBlock.LinkTo(bBlock, new DataflowLinkOptions { PropagateCompletion = true })

for (int pageNumber = 1; pageNumber < totalPages; pageNumber++)
{
    aBlock.Post(pageNumber);
}

aBlock.Complete();
await aBlock.Completion;

具有进度更新的并行I / O查询

1 个答案: