Aiursoft InMemoryKvDb

Aiursoft InMemoryKvDb is a lightweight, thread-safe, in-memory key-value database with support for automatic Least Recently Used (LRU) cache eviction. It allows for efficient storage and retrieval of key-value pairs while preventing unbounded memory usage by leveraging configurable LRU eviction policies.

This library is ideal for scenarios where you need an in-memory cache that automatically discards the least recently accessed items, such as storing temporary user data, caching API responses, or handling in-memory operations for temporary data processing, without worrying about potential memory overflows.

Why this project

The traditional way to create an In-Memory Key-Value Database in C# is:

public class InMemoryDatabase : ISingletonDependency
{
    private ConcurrentDictionary<Guid, Player> Players { get; } = new();
    
    public Player GetOrAddPlayer(Guid id)
    {
        lock (Players)
        {
            return Players.GetOrAdd(id, _ => new Player(id)
            {
                NickName = "Anonymous " + new Random().Next(1000, 9999)
            });
        }
    }
    
}

However, if a hacker keeps calling GetOrAddPlayer with a new Guid, the Players dictionary will grow infinitely. And cause you OutOfMemoryException.

Installation

First, install Aiursoft.InMemoryKvDb to your ASP.NET Core project from nuget.org:

dotnet add package Aiursoft.InMemoryKvDb

Add the service to your IServiceCollection in Startup.cs (or Program.cs in .NET 6 and later):

Usage Methods

1. AddNamedLruMemoryStore<T, TK>
2. AddNamedLruMemoryStoreManualCreate<T, TK>
3. AddLruMemoryStore<T, TK>
4. AddLruMemoryStoreManualCreate<T, TK>

Differences and How to Choose

• Named vs. Non-Named Stores:

  • Named stores (AddNamedLruMemoryStore and AddNamedLruMemoryStoreManualCreate) allow you to create multiple isolated caches identified by unique names, suitable for scenarios where you need separate caches within the same application.
  • Non-named stores (AddLruMemoryStore and AddLruMemoryStoreManualCreate) are simpler and provide a single cache instance.

• Automatic vs. Manual Key-Value Creation:

  • Automatic creation (AddLruMemoryStore and AddNamedLruMemoryStore) uses an onNotFound function to generate values for missing keys automatically.
  • Manual creation (AddLruMemoryStoreManualCreate and AddNamedLruMemoryStoreManualCreate) requires explicit value creation when adding items, providing greater control over how values are added to the cache.

Example Usages

1. Using AddNamedLruMemoryStore<T, TK>

var services = new ServiceCollection();
services.AddNamedLruMemoryStore<Player, Guid>(
    id => new Player(id, "GeneratedPlayer"),
    maxCachedItemsCount: 5);
var serviceProvider = services.BuildServiceProvider();
var namedProvider = serviceProvider.GetService<NamedLruMemoryStoreProvider<Player, Guid>>();
var store = namedProvider.GetStore("player-store");
var player = store.GetOrAdd(Guid.NewGuid());

2. Using AddNamedLruMemoryStoreManualCreate<T, TK>

var services = new ServiceCollection();
services.AddNamedLruMemoryStoreManualCreate<Player, Guid>(maxCachedItemsCount: 5);
var serviceProvider = services.BuildServiceProvider();
var namedProvider = serviceProvider.GetService<NamedLruMemoryStoreManualCreatedProvider<Player, Guid>>();
var store = namedProvider.GetStore("player-store");
var player = store.GetOrAdd(Guid.NewGuid(), id => new Player(id, "ManualPlayer"));

3. Using AddLruMemoryStore<T, TK>

var services = new ServiceCollection();
services.AddLruMemoryStore<Player, Guid>(
    id => new Player(id, "GeneratedPlayer"),
    maxCachedItemsCount: 3);
var serviceProvider = services.BuildServiceProvider();
var store = serviceProvider.GetService<LruMemoryStore<Player, Guid>>();
var player = store.GetOrAdd(Guid.NewGuid());

4. Using AddLruMemoryStoreManualCreate<T, TK>

var services = new ServiceCollection();
services.AddLruMemoryStoreManualCreate<Player, Guid>(maxCachedItemsCount: 3);
var serviceProvider = services.BuildServiceProvider();
var store = serviceProvider.GetService<LruMemoryStoreManualCreated<Player, Guid>>();
var player = store.GetOrAdd(Guid.NewGuid(), id => new Player(id, "ManualPlayer"));

Choose the appropriate method based on whether you need isolated named stores and whether you prefer automatic or manual value creation.

Contributing

Contributions are welcome! Please open an issue or submit a pull request for any feature requests, bug fixes, or other improvements.