ZeroAlloc.Mediator 1.1.3

ZeroAlloc.Mediator

ZeroAlloc.Mediator is a source-generated, zero-allocation mediator for .NET 8 and .NET 10. It supports request/response, notifications, and streaming without reflection or dynamic dispatch. The source generator eliminates the runtime overhead that reflection-based mediators incur by wiring all dispatch at compile time — no dictionaries, no virtual dispatch, no delegate allocation per request.

Install

dotnet add package ZeroAlloc.Mediator

The generator package must also be added as an analyzer:

<PackageReference Include="ZeroAlloc.Mediator.Generator" Version="*" OutputItemType="Analyzer" ReferenceOutputAssembly="false" />

Example

// 1. Define a request record and its expected response type
public readonly record struct CreateOrder(string Product, int Qty) : IRequest<OrderId>;

// 2. Implement a handler — constructor-injected dependencies are supported
public class CreateOrderHandler(IOrderRepository repo) : IRequestHandler<CreateOrder, OrderId>
{
    public async ValueTask<OrderId> Handle(CreateOrder request, CancellationToken ct)
    {
        var id = await repo.InsertAsync(request.Product, request.Qty, ct);
        return new OrderId(id);
    }
}

// 3. Register IMediator with DI (the generator emits MediatorService automatically)
services.AddSingleton<IMediator, MediatorService>();

// 4. Send the request and use the result — fully strongly-typed, zero allocation
public class OrderController(IMediator mediator)
{
    public async Task<IResult> PlaceOrder(CreateOrder cmd, CancellationToken ct)
    {
        var id = await mediator.Send(cmd, ct);   // returns OrderId, no boxing
        return Results.Created($"/orders/{id}", id);
    }
}

Performance

ZeroAlloc.Mediator is 26–65x faster than MediatR with zero heap allocation on all synchronous paths (.NET 10, BenchmarkDotNet).

See docs/performance.md for the full benchmark table and zero-allocation design explanation.

Features

• Request/Response — strongly-typed Send overloads per request type
• Notifications — sequential or parallel ([ParallelNotification]) dispatch
• Streaming — IAsyncEnumerable<T> via CreateStream
• Pipeline Behaviors — compile-time inlined middleware chain (logging, validation, etc.)
• Polymorphic Notifications — base interface handlers are automatically included in concrete notification dispatch
• Analyzer Diagnostics — missing handlers, duplicates, and misconfigurations are build errors/warnings
• Zero Allocation — ValueTask, readonly record struct, static dispatch, no closures
• Native AOT Compatible — no reflection at runtime; all dispatch is resolved at compile time by the source generator

Documentation

License

MIT