C# Language ActionBlock


Example

(foreach)

This class can be thought of logically as a buffer for data to be processed combined with tasks for processing that data, with the “dataflow block” managing both. In its most basic usage, we can instantiate an ActionBlock and “post” data to it; the delegate provided at the ActionBlock’s construction will be executed asynchronously for every piece of data posted.

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Synchronous Computation

var ab = new ActionBlock<TInput>(i => 
{
    Compute(i);
});
…
ab.Post(1);
ab.Post(2);
ab.Post(3);

Throttling Asynchronous Downloads to at most 5 concurrently

var downloader = new ActionBlock<string>(async url =>
{
    byte [] imageData = await DownloadAsync(url);
    Process(imageData);
}, new DataflowBlockOptions { MaxDegreeOfParallelism = 5 }); 

downloader.Post("http://website.com/path/to/images");
downloader.Post("http://another-website.com/path/to/images");

Introduction to TPL Dataflow by Stephen Toub