Benchmarks.md

Compared to MediatR

Note: like MediatR, all handlers are registered as transient with the exception of delegate handlers.

BenchmarkDotNet=v0.13.1, OS=Windows 10.0.22000 (Windows 11)
AMD Ryzen 9 5950X, 1 CPU, 32 logical and 16 physical cores
.NET SDK=6.0.201
  [Host]     : .NET 6.0.3 (6.0.322.12309), X64 RyuJIT
  DefaultJob : .NET 6.0.3 (6.0.322.12309), X64 RyuJIT

Results

Empty Class

public record Ping : IRequest<string>;

Method	Mean	Error	StdDev	Ratio	RatioSD	Gen 0	Allocated
Handler_AsInterface	11.059 ns	0.0446 ns	0.0372 ns	1.00	0.00	0.0014	24 B
Handler_AsClass	7.724 ns	0.0321 ns	0.0251 ns	0.70	0.00	-	-
MediatR_Interface	504.845 ns	2.0148 ns	1.7860 ns	45.66	0.18	0.0849	1,424 B
MediatR_Object	541.339 ns	2.7988 ns	2.4810 ns	48.93	0.26	0.0887	1,496 B
Zapto_Generic	35.229 ns	0.1626 ns	0.1441 ns	3.18	0.02	0.0029	48 B
Zapto_Interface	64.481 ns	0.4158 ns	0.3472 ns	5.83	0.03	0.0081	136 B
Zapto_Object	85.953 ns	0.5875 ns	0.5495 ns	7.77	0.06	0.0081	136 B

Empty Struct

public record struct Ping : IRequest<string>;

Method	Mean	Error	StdDev	Ratio	RatioSD	Gen 0	Allocated
Handler_AsInterface	9.463 ns	0.0331 ns	0.0309 ns	1.00	0.00	-	-
Handler_AsClass	9.583 ns	0.0346 ns	0.0324 ns	1.01	0.00	-	-
MediatR_Interface	509.057 ns	2.5120 ns	2.2268 ns	53.81	0.29	0.0849	1,424 B
MediatR_Object	530.815 ns	4.1636 ns	3.6909 ns	56.12	0.45	0.0887	1,496 B
Zapto_Generic	34.860 ns	0.1928 ns	0.1709 ns	3.69	0.03	0.0014	24 B
Zapto_Interface	63.125 ns	0.5586 ns	0.4952 ns	6.67	0.05	0.0081	136 B
Zapto_Object	82.246 ns	0.5049 ns	0.4723 ns	8.69	0.05	0.0081	136 B

Explanation

Handler

Without any mediator the request is executed directly from the handler.

As class

var handler = new RequestHandler();

var response = await handler.Handle(new Request("parameter"), CancellationToken.None);

As interface

IRequestHandler<Request, string> handler = new RequestHandler();

var response = await handler.Handle(new Request("parameter"), CancellationToken.None);

Generic request parameter

With Zapto, it's possible to send a request with the request and response types. This can be used to avoid boxing, especially when using structs. MediatR has a pull request open to implement this feature, but it hasn't been merged because it's ugly to specify all arguments. If you use atleast C# 9, it's possible to use the source generator to automaticly generate extension methods.

Example

var response = await _mediator.Send<Request, Response>(new Request("parameter"));

// With source generator
var response = await _mediator.RequestAsync("parameter");

Interface

With only the response generic parameter, C# can automaticly detect the response type from the request interface. The downside to this is that you have to find the request type, make a generic type for the handler and box the request.

Example

var response = await _mediator.Send(new Request("parameter"));

Object

It's possible that the request is only an object. In this case the request and response have to be boxed. This is the worst case secenario.

Example

object request = new Request("parameter");

var response = await _mediator.Send(request);

Handler registration

It's possible to register handlers different ways.

Results

Method	Mean	Error	StdDev	Ratio	RatioSD	Gen 0	Allocated
Class	33.79 ns	0.168 ns	0.157 ns	1.00	0.00	0.0014	24 B
Class_Namespace	87.82 ns	1.062 ns	0.993 ns	2.60	0.02	0.0086	144 B
Delegate	34.29 ns	0.094 ns	0.088 ns	1.01	0.00	-	-
Delegate_Namespace	64.41 ns	0.476 ns	0.445 ns	1.91	0.01	0.0072	120 B
Generic	133.90 ns	0.568 ns	0.503 ns	3.96	0.02	0.0057	96 B

Explanation

Class

With the class handler, the implementation is provided in a class.

public sealed class PingHandlerZapto : IRequestHandler<Ping, string>
{
    public ValueTask<string> Handle(Ping request, CancellationToken cancellationToken)
    {
        return new ValueTask<string>("Pong");
    }
}

services.AddRequestHandler<Ping, string, PingHandlerZapto>();

Delegate

With the delagete handler, the implementation is provided through a delegate. This is comparable to ASP.NET Core minimal API.

services.AddRequestHandler((PingDelegate _) => "pong");

Namespace

In addition to the class (or delegate) handler, it's possible to add a custom namespace to execute different handlers for the same request.

var ns = new MediatorNamespace("CustomNamespace")

services.AddRequestHandler<Ping, string, PingHandlerZapto>(ns);

Generic

When your request type has a generic type, you must provide the implementation through a class handler.

public record struct ReturnGeneric<T>(T Value) : IRequest<T>;

public class ReturnStructGenericHandlerZapto<T> : IRequestHandler<ReturnStructGeneric<T>, T>
{
    public ValueTask<T> Handle(ReturnStructGeneric<T> request, CancellationToken cancellationToken)
        => new(request.Value);
}

services.AddRequestHandler(typeof(ReturnStructGenericHandlerZapto<>));