Caching has always been a critical component of building performant and scalable applications. In .NET 9, Microsoft introduced Hybrid Cache, a revolutionary approach to caching that bridges the gap between in-memory and distributed caching. This new abstraction simplifies managing multi-level caches, offering developers the flexibility and performance they need for modern applications. In this article, we’ll demonstrate how to set up, register, configure, and use Hybrid Cache, including examples of the DefaultHybridCache implementation.

What is Hybrid Cache?

Hybrid Cache in .NET 9 combines the best of in-memory caching (fast, local access) and distributed caching (durability and shared state across servers). It introduces an abstract class, HybridCache, and its default implementation, DefaultHybridCache. This abstraction enables seamless integration of various caching layers, allowing developers to write clean, scalable, and maintainable code. Key features include:

• Multi-Level Caching: Combines in-memory and distributed cache layers for optimized performance.
• Eviction by Tags: Supports advanced scenarios like targeted eviction of cache entries.
• Serialization Flexibility: Offers support for custom serializers for cache keys and values.
• Asynchronous Operations: Designed for async-only workflows to align with modern application patterns.

Real-World Use Cases

• E-Commerce Platforms
  Hybrid Cache can be a game-changer for online retail applications, which require quick access to frequently used data, such as product details and user sessions. The in-memory cache layer ensures ultra-fast responses for active sessions, while the distributed cache layer maintains consistency across multiple nodes for scalability during peak shopping seasons.
• Content Delivery Networks (CDNs)
  CDNs benefit from Hybrid Cache by caching static assets locally for faster delivery to end-users while maintaining a distributed cache for dynamic, personalized content. This multi-level approach ensures high-speed access and reduced load on the origin servers.
• Financial Applications
  In fintech, data consistency and speed are critical. Hybrid Cache supports secure, high-performance caching for sensitive data like transaction records and account balances, ensuring both speed and fault tolerance in distributed systems.
• Microservices Architectures
  In microservices-based applications, where services often run in different environments, Hybrid Cache bridges the gap by providing local in-memory caching for individual services and a shared distributed cache for inter-service communication.

Advantages of Hybrid Cache in .NET 9

• Performance Optimization: Reduces database hits and network latency by leveraging in-memory caching for hot data.
• Cost Efficiency: Minimizes cloud infrastructure costs by optimizing data storage and retrieval mechanisms.
• Developer Productivity: Simplifies implementation with a unified caching API, reducing boilerplate code.
• Flexibility: Allows granular control over caching strategies, such as tiered eviction policies and serialization options.

Setting Up Hybrid Cache

Prerequisites

1. .NET 9 SDK installed on your machine.
2. A project where caching is required (e.g., ASP.NET Core application).
3. NuGet packages for distributed caching providers, such as Microsoft.Extensions.Caching.StackExchangeRedis.

Example: Install Required NuGet Packages

Run the following command to add the necessary packages:

dotnet add package Microsoft.Extensions.Caching.StackExchangeRedis
dotnet add package Microsoft.Extensions.Caching.Memory

Registering Hybrid Cache in .NET 9

To use Hybrid Cache, first register the services in the Program.cs file.

Example: Register Hybrid Cache Services

using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Caching.Hybrid;

var builder = WebApplication.CreateBuilder(args);

// Add memory cache
builder.Services.AddMemoryCache();

// Add Redis distributed cache
builder.Services.AddStackExchangeRedisCache(options =>
{
    options.Configuration = "localhost:6379"; // Replace with your Redis server connection string
});

// Add Hybrid Cache
builder.Services.AddHybridCache(options =>
{
    options.DefaultCacheDuration = TimeSpan.FromMinutes(5); // Set default cache duration
});

Configuring Hybrid Cache

Hybrid Cache allows for customization, such as eviction policies and serializers.

Example: Configure Hybrid Cache Services

builder.Services.Configure<HybridCacheOptions>(options =>
{
    options.DefaultCacheDuration = TimeSpan.FromMinutes(10); // Custom duration
    options.Serializer = new JsonHybridCacheSerializer(); // Use JSON serialization
    options.EvictionPolicy = HybridCacheEvictionPolicy.FirstLevel | HybridCacheEvictionPolicy.SecondLevel;
});

Using Hybrid Cache

Once registered, Hybrid Cache can be injected and used in your services or controllers.

Example: Storing and Retrieving Data with Hybrid Cache

using Microsoft.Extensions.Caching.Hybrid;

public class ProductService
{
    private readonly IHybridCache _hybridCache;

    public ProductService(IHybridCache hybridCache)
    {
        _hybridCache = hybridCache;
    }

    public async Task<Product> GetProductAsync(int productId)
    {
        // Cache key
        string cacheKey = $"Product_{productId}";

        // Try to get the product from cache
        var product = await _hybridCache.GetAsync<Product>(cacheKey);

        if (product == null)
        {
            // Simulate retrieving data from database
            product = new Product
            {
                Id = productId,
                Name = "Sample Product",
                Price = 99.99
            };

            // Store the product in cache
            await _hybridCache.SetAsync(cacheKey, product, TimeSpan.FromMinutes(5));
        }

        return product;
    }
}

The introduction of Hybrid Cache in .NET 9 marks a significant advancement in caching technology, providing developers with a powerful tool to build high-performance and scalable applications. By combining in-memory and distributed caches, Hybrid Cache bridges the gap between speed and reliability, catering to diverse application scenarios. Whether you’re optimizing an e-commerce platform, building a microservices architecture, or developing a CDN, Hybrid Cache offers the flexibility and power to elevate your application performance.