Tamir Dresher - Async Streams in C#
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The document discusses asynchronous programming in C#, covering various patterns such as the Event Asynchronous Pattern and the Task Asynchronous Pattern. It highlights the use of async streams and async enumerables, providing code examples for reading lines from a CSV file asynchronously. Additionally, it emphasizes best practices like avoiding synchronous wrappers and using cancellation tokens for efficient async operations.
![Async stream example
public static async Task Main()
{
var records = ReadLines("transactions.csv");
await foreach (var record in records)
{
Console.WriteLine($"Transaction from {record[0]} to {record[1]}");
}
}
public static async IAsyncEnumerable<string[]> ReadLines(string path)
{
var lines = await System.IO.File.ReadAllLinesAsync(path);
foreach (var line in lines)
{
yield return line.Split(',');
}
}](https://image.slidesharecdn.com/tamirdresher-dotnetasyncstreams-210421081726/85/Tamir-Dresher-Async-Streams-in-C-8-320.jpg)
Tamir Dresher - Async Streams in C#
- 1. Async Streams in C# Tamir Dresher Twitter: @tamir_dresher
- 2. 2 System Architect @ @tamir_dresher Tamir Dresher My Books: Software Engineering Lecturer Ruppin Academic Center https://www.israelclouds.com/iasaisrael https://tinyurl.com/Telescopim-YouTube
- 3. Async work in C# .NET 2.0 - Event Asynchronous Pattern (Async method + event) .NET 1.1 Asynchronous Programming Model (Begin/End Methods) .NET 4.5 Task Asynchronous Pattern C# 7.0 Async Main C# 5.0 Async Await C# 8 - Async Streams - Async Disposables Single Value • IObservable<T> , IObserver<T> • Reactive Extensions (Rx)
- 6. Sync over Async Avoid Exposing Synchronous Wrappers for Asynchronous Implementations Sync over async will lead to ThreadPool starvation on high load Thread Pool Thread Request Async IO Thread
- 7. IAsyncEnumerable namespace System.Collections.Generic { public interface IAsyncEnumerable<out T> { IAsyncEnumerator<T> GetAsyncEnumerator( CancellationToken cancellationToken = default); } public interface IAsyncEnumerator<out T> : IAsyncDisposable { ValueTask<bool> MoveNextAsync(); T Current { get; } } } SharpLab namespace System { public interface IAsyncDisposable { ValueTask DisposeAsync(); } } namespace System.Collections.Generic { public interface IEnumerable<out T> : IEnumerable { IEnumerator<T> GetEnumerator(); } public interface IEnumerator<out T> : IDisposable, IEnumerator { bool MoveNext (); T Current { get; } } }
- 8. Async stream example public static async Task Main() { var records = ReadLines("transactions.csv"); await foreach (var record in records) { Console.WriteLine($"Transaction from {record[0]} to {record[1]}"); } } public static async IAsyncEnumerable<string[]> ReadLines(string path) { var lines = await System.IO.File.ReadAllLinesAsync(path); foreach (var line in lines) { yield return line.Split(','); } }
- 9. Summary Single Value Multiple Value Sync T IEnumerable<T> Async Task<T> IAsyncEnumerable<T> IObservable<T> Avoid as much as possible Sync-Over-Async Cancellation - Mark the CancelleationToken parameter with EnumeratorCancellation attribute and use the WithCancellation() extension method propagate the token Use the System.Linq.Async and System.Interactive.Async NuGet packages to add async LINQ operators @tamir_dresher