LVD.ServiceStack.RoutedCacheClient 1.0.0

ServiceStack Routed Cache Client

What

The ServiceStack Routed Cache Client is an ICacheClient implementation (ICacheClientExtended to be more exact) that acts as a facade to a collection of multiple other cache clients. It has minimum overhead and does not store cache values itself, but only routes various cache operations (read, write, flush, remove etc.) to a specific registered client, based on an associated rule (for instance, whether the key starts with a given string).

Why

The main issue for me was (and possibly many others) that I could not register a different cache client for session storage (say, OrmLiteCacheClient), whilst continuing to make use of the standard MemoryCacheClient .

Installation

Available as a NuGet package, here.

Via Package Manager

Install-Package LVD.ServiceStack.RoutedCacheClient -Version 1.0.0

Via .NET CLI

dotnet add package LVD.ServiceStack.RoutedCacheClient --version 1.0.0

How to use

1. Add namespace referance

using LVD.ServiceStackRoutedCacheClient.

2. Create your routed cache client instance

In this example, the default MemoryCacheClient provided by ServiceStack is used as a fallback client.

IRoutedCacheClient routedCacheClient = new DefaultRoutedCacheClient(new MemoryCacheClient());

3. Register your other cache clients

For example, registering a ServiceStack OrmLite cache client for ServiceStack sessions:

OrmLiteCacheClient<CacheEntry> ormLiteCacheClient =
    new OrmLiteCacheClient<CacheEntry>();

routedCacheClient.PushClientWithRule(new KeyStartsWithStringCacheClientRule(ormLiteCacheClient,
    StringComparison.InvariantCultureIgnoreCase,
    "urn:iauthsession:",
    "sess:"));

Or simpler, using PushServiceStackSessionCacheClient(), which automatically registers your provided cache client with a KeyStartsWithStringCacheClientRule and the above prefixes: urn:iauthsession: and sess:.

OrmLiteCacheClient<CacheEntry> ormLiteCacheClient =
    new OrmLiteCacheClient<CacheEntry>();

routedCacheClient.PushServiceStackSessionCacheClient(ormLiteCacheClient);

4. Creating Custom Rules

The library only comes with a handful of rules, but creating your own is as easy as extending the BaseCacheClientRule class and providing an implementation for the bool Match(string key) method.

As an example, here is the implementation of the built-in KeyStartsWithStringCacheClientRule rule:

public class KeyStartsWithStringCacheClientRule : BaseCacheClientRule
{
    private List<string> mTokens = new List<string>();

    private StringComparison mStringComparisonMode;

    public KeyStartsWithStringCacheClientRule(ICacheClient cacheClient,
        StringComparison stringComparisonMode,
        params string[] tokens)
        : base(cacheClient)
    {
        if (tokens == null || tokens.Length == 0)
        throw new ArgumentNullException(nameof(tokens));

        mTokens.AddRange(tokens);
        mStringComparisonMode = stringComparisonMode;
    }

    public override bool Matches(string key)
    {
        if (string.IsNullOrWhiteSpace(key))
        throw new ArgumentNullException(nameof(key));

        foreach (string token in mTokens)
        if (key.StartsWith(token, mStringComparisonMode))
            return true;

        return false;
    }

    public StringComparison StringComparisonMode => mStringComparisonMode;
}