DistributedCache

DistributedCache is an open source caching abstraction layer for .NET which supports Redis, SQL Server, InMemory, with automatic failure recovery, heath checks, automatic table generation (MSSQL), logging and also allows to clear all keys.

It simplifies cache usage by allowing developers to inject it into the application and use it anywhere without having to worry about configuration for an specific infrastructure (InMemory, Redis, SQL server).

It is as fast as a cache interface can be and also includes the feature of CLEAR ALL keys and CLEAR ALL WITH PREFIX which were both missing from IDistributedCache.

---

Usage

Setting/Getting values from cache

Just inject and use the ICache interface to store or obtain values from the cache like the example below:

public class CountryManager
{
    private readonly ICache _cache;

    public CountryManager(ICache cache)
    {
        _cache = cache;
    }

    public async Task<List<CountryData>> GetAllCountriesAsync(CancellationToken cancellationToken)
    {
        var cacheKey = "some cache key";

        var cachedValue = await _cache.GetCacheValueAsync<List<CountryData>>(cacheKey, cancellationToken);
        if (cachedValue != null)
        {
            return cachedValue;
        }

        var dataValue = await GetAllCountriesFromRepositoryAsync();
        _ = _cache.SetCacheValueAsync(cacheKey, dataValue);

        return dataValue;
    }
}

Setting cache TTL

There are 2 ways to achieve that:

1. Using a default TTL (see configuration section)
2. Overriding the default TTL on a case-by-case basis like this:

var ttl = new DistributedCacheEntryOptions
{
    AbsoluteExpirationRelativeToNow = TimeSpan.FromSeconds(60),
    SlidingExpiration = TimeSpan.FromSeconds(30)
};
_ = _cache.SetCacheValueAsync(cacheKey, dataValue, ttl, cancellationToken);

Configuration

Scenario 1: InMemory Cache

This is the most basic, yet common, scenario in which the application uses a cache in memory to increase the performance of a single instance of an application.

services.AddDistributedCache(options =>
{
    options.Configure(CacheType.InMemory);
});

Scenario 2: Redis with automatic failure recovery

This configuration use redis infrastructure and will check if it is healthy, in case of repeated failures (maxErrorsAllowed) it will automatically disable the cache and will check again in the interval given (resetIntervalMinutes).

var connectionString = "some cache connection string";
services.AddDistributedCache(options =>
{
    options.Configure(CacheType.Redis, connectionString, "myApplicationCacheInstance")
        .ConfigureHealthCheck(enabled:true, maxErrorsAllowed:5, resetIntervalMinutes:2);
});