FusionCache

FusionCache is an easy to use, fast and robust hybrid cache with advanced resiliency features.

It was born after years of dealing with all sorts of different types of caches: memory caching, distributed caching, http caching, CDNs, browser cache, offline cache, you name it. So I've tried to put together these experiences and came up with FusionCache.

Being a hybrid cache means it can transparently work as either a normal memory cache (L1) or as a multi-level cache (L1+L2), where the distributed 2nd level (L2) can be any implementation of the standard IDistributedCache interface: this will get us better cold starts, better horizontal scalability, more resiliency and overall better performance.

FusionCache also includes an optional backplane for realtime sync between multiple nodes and advanced resiliency features like cache stampede protection, a fail-safe mechanism, soft/hard timeouts, eager refresh, full observability via logging and OpenTelemetry and much more.

🏆 Award

On August 2021, FusionCache received the Google Open Source Peer Bonus Award: here is the official blogpost.

📕 Getting Started

With 🦄 A Gentle Introduction you'll get yourself comfortable with the overall concepts.

Want to start using it immediately? There's a ⭐ Quick Start for you.

Curious about what you can achieve from start to finish? There's a 👩‍🏫 Step By Step guide.

In search of all the docs? There's a page for that, too.

📺 Media

More into videos?

I've been lucky enough to be invited on some shows and podcasts here and there: you can find them in the Media section.

A good example is when the fine folks at On .NET invited me on the show to allow me to mumbling random caching stuff.

✔ Features

These are the key features of FusionCache:

• 🛡️ Cache Stampede: automatic protection from the Cache Stampede problem
• 🔀 2nd level: an optional 2nd level handled transparently, with any implementation of IDistributedCache
• 💣 Fail-Safe: a mechanism to avoids transient failures, by reusing an expired entry as a temporary fallback
• ⏱ Soft/Hard Timeouts: a slow factory (or distributed cache) will not slow down your application, and no data will be wasted
• 📢 Backplane: in a multi-node scenario, it can notify the other nodes about changes in the cache, so all will be in-sync
• ↩️ Auto-Recovery: automatic handling of transient issues with retries and sync logic
• 🧙‍♂️ Adaptive Caching: for when you don't know upfront the cache duration, as it depends on the value being cached itself
• 🔂 Conditional Refresh: like HTTP Conditional Requests, but for caching
• 🦅 Eager Refresh: start a non-blocking background refresh before the expiration occurs
• 🔃 Dependency Injection + Builder: native support for Dependency Injection, with a nice fluent interface including a Builder support
• 📛 Named Caches: easily work with multiple named caches, even if differently configured
• ♊ Auto-Clone: be sure that cached values returned can be safely modified
• 🔭 OpenTelemetry: native observability support via OpenTelemetry
• 🚀 Background Distributed Operations: distributed operations can easily be executed in the background, safely, for better performance
• 📜 Logging: comprehensive, structured and customizable, via the standard ILogger interface
• 💫 Fully sync/async: native support for both the synchronous and asynchronous programming model
• 📞 Events: a comprehensive set of events, both at a high level and at lower levels (memory/distributed)
• 🧩 Plugins: extend FusionCache with additional behavior like adding support for metrics, statistics, etc...

⭐ Quick Start

FusionCache can be installed via the nuget UI (search for the ZiggyCreatures.FusionCache package) or via the nuget package manager console:

PM> Install-Package ZiggyCreatures.FusionCache

As an example, imagine having a method that retrieves a product from your database:

Product GetProductFromDb(int id) {
	// YOUR DATABASE CALL HERE
}

💡 This is using the sync programming model, but it would be equally valid with the newer async one for even better performance.

To start using FusionCache the first thing is create a cache instance:

var cache = new FusionCache(new FusionCacheOptions());

If instead you are using DI (Dependency Injection) use this:

services.AddFusionCache();

We can also specify some global options, like a default FusionCacheEntryOptions object to serve as a default for each call we'll make, with a duration of 2 minutes and a Low priority:

var cache = new FusionCache(new FusionCacheOptions() {
	DefaultEntryOptions = new FusionCacheEntryOptions {
		Duration = TimeSpan.FromMinutes(2),
		Priority = CacheItemPriority.Low
	}
});

Or, using DI, like this:

services.AddFusionCache()
	.WithDefaultEntryOptions(new FusionCacheEntryOptions {
		Duration = TimeSpan.FromMinutes(2),
		Priority = CacheItemPriority.Low
	})
;

Now, to get the product from the cache and, if not there, get it from the database in an optimized way and cache it for 30 sec simply do this:

var id = 42;

cache.GetOrSet<Product>(
	$"product:{id}",
	_ => GetProductFromDb(id),
	TimeSpan.FromSeconds(30)
);

That's it 🎉

🖥️ Simulator

Distributed systems are, in general, quite complex to understand.

When using FusionCache with the distributed cache, the backplane and auto-recovery the Simulator can help us seeing the whole picture.

🧰 Supported Platforms

FusionCache targets .NET Standard 2.0 so any compatible .NET implementation is fine: this means .NET Framework (the old one), .NET Core 2+ and .NET 5/6+ (the new ones), Mono 5.4+ and more (see here for a complete rundown).

NOTE: if you are running on .NET Framework 4.6.1 and want to use .NET Standard packages Microsoft suggests to upgrade to .NET Framework 4.7.2 or higher (see the .NET Standard Documentation) to avoid some known dependency issues.

💼 Is it Production Ready :tm: ?

Yes!

FusionCache is being used in production on real world projects for years, happily handling millions of requests.

Considering that the FusionCache packages have been downloaded more than 6 million times (thanks everybody!) it may very well be used even more.

And again, if you are using it please ✉ drop me a line, I'd like to know!