AsyncEnumerator 1.4.2

Introduces IAsyncEnumerable, IAsyncEnumerator, ForEachAsync(), and ParallelForEachAsync()
GitHub: https://github.com/tyrotoxin/AsyncEnumerable

PROBLEM SPACE

Helps to (a) create an element provider, where producing an element can take a lot of time
due to dependency on other asynchronous events (e.g. wait handles, network streams), and
(b) a consumer that processes those element as soon as they are ready without blocking
the thread (the processing is scheduled on a worker thread instead).


EXAMPLE

using System.Collections.Async;

static IAsyncEnumerable<int> ProduceAsyncNumbers(int start, int end)
{
 return new AsyncEnumerable<int>(async yield => {

   // Just to show that ReturnAsync can be used multiple times
   await yield.ReturnAsync(start);

   for (int number = start + 1; number <= end; number++)
     await yield.ReturnAsync(number);

   // You can break the enumeration loop with the following call:
   yield.Break();

   // This won't be executed due to the loop break above
   await yield.ReturnAsync(12345);
 });
}

// Just to compare with synchronous version of enumerator
static IEnumerable<int> ProduceNumbers(int start, int end)
{
 yield return start;

 for (int number = start + 1; number <= end; number++)
   yield return number;

 yield break;

 yield return 12345;
}

static async Task ConsumeNumbersAsync()
{
 var asyncEnumerableCollection = ProduceAsyncNumbers(start: 1, end: 10);
 await asyncEnumerableCollection.ForEachAsync(async number => {
   await Console.Out.WriteLineAsync($"{number}");
 });
}

// Just to compare with synchronous version of enumeration
static void ConsumeNumbers()
{
 // NOTE: IAsyncEnumerable is derived from IEnumerable, so you can use either
 var enumerableCollection = ProduceAsyncNumbers(start: 1, end: 10);
 //var enumerableCollection = ProduceNumbers(start: 1, end: 10);

 foreach (var number in enumerableCollection) {
   Console.Out.WriteLine($"{number}");
 }
}