README.md

Composable Async

Create, compose and inject asynchronous behaviors in .Net Framework and .Net Core.

Goal

• Create asynchronous behavior such as fiber, rate limiter, circuit breaker.

• Compose these behaviors and use them as building blocks with aspect oriented programming.

• Provide a lightweight way inject these behaviors to transform POCOs in actors.

Create asynchronous behavior

Asynchronous behaviors are implemented using IDispatcher abstraction.

Composable Async provides various dispatchers implementation:

Retry

// Create dispatcher that catch all ArgumentException and retry for ever with a delay of 200 ms
var retryDispatcher = RetryPolicy.For<ArgumentException>()
			.WithWaitBetweenRetry(TimeSpan.FromSeconds(0.2))
			.ForEver();

See more at ComposableAsync.Resilient

Circuit-Breaker

// Create dispatcher that catch all ArgumentException and retry for ever with a delay of 200 ms
var retryDispatcher = CircuitBreakerPolicy.For<TimeoutException>()
			.WithRetryAndTimeout(10, TimeSpan.FromMilliseconds(500));

See more at ComposableAsync.Resilient

Fiber

// Create dispatcher that dispatch all action on the same thread
var fiberDispatcher = Fiber.CreateMonoThreadedFiber();

See more at ComposableAsync.Concurrent

RateLimiter

// Create dispatcher that dispatch all action on the same thread
var timeConstraint = TimeLimiter.GetFromMaxCountByInterval(5, TimeSpan.FromSeconds(1));

See more at RateLimiter

Compose dispatchers

Use then extension methods to create a dispatcher that will execute sequentially dispatchers

/// <summary>
/// Returns a composed dispatcher applying the given dispatchers sequentially
/// </summary>
/// <param name="dispatcher"></param>
/// <param name="others"></param>
/// <returns></returns>
public static IDispatcher Then(this IDispatcher dispatcher, IEnumerable<IDispatcher> others)

var composed = fiberDispatcher.Then(timeConstraint);

Use dispatchers

Await dispatcher

await fiberDispatcher;
// After the await, the code executes in the dispatcher context
// In this case the code will execute on the fiber thread
Console.WriteLine($"This is fiber thread {Thread.CurrentThread.ManagedThreadId}");

As httpDelegateHandler

Transform a dispatcher into HttpMessageHandler with AsDelegatingHandler extension method:

/// Using time limiter nuget
var handler = TimeLimiter
	.GetFromMaxCountByInterval(60, TimeSpan.FromMinutes(1))
	.AsDelegatingHandler();
var client = new HttpClient(handler);

As wrapper for proxy Factory

Using ComposableAsync.Factory, with this option all methods call to the proxyfied object are wrapped using the provided dispatcher.

var retryDispatcher = RetryPolicy.For<SystemException>().ForEver();

var originalObject = new BusinessObject();
var proxyFactory = new ProxyFactory(retryDispatcher);
var proxyObject = proxyFactory.Build<IBusinessObject>(originalObject);

// The call to the originalObject will be wrapped into a retry policy for SystemException
var res = await proxyObject.Execute(cancellationToken);

Actors

ComposableAsync.Concurrent also provides an actor factory based on fiber and proxy factory.

// Instantiate actor factory
var builder = new ActorFactoryBuilder();
var factory = builder.GetActorFactory(shared: false);
// When shared is true, all actor leaves in the same thread,
// when shared is false, each actor leaves in its own thread.

// Instantiate an actor from a POCO
var fooActor = fact.Build<IFoo>(new ConcreteFoo());

See more at ComposableAsync.Concurrent

Nuget

For core functionality:

Install-Package ComposableAsync.Core

For factories:

Install-Package ComposableAsync.Factory

For actors:

Install-Package ComposableAsync.Concurrent

For retry and circuit-breaker:

Install-Package ComposableAsync.Resilient

Go nuget packages