Caching Appenders

Caching Appenders

• .Cache(...)
• .CacheAllItems(...)
• .InvalidateCache(...)
• .ReadOrCache(...)

Cache Keys

Cache keys can be provided as a string or a function. In the latter case, the function accepts the result of the chain and returns a string.

.CacheAllItems(...) is a special case. It only operates on lists of objects and generates a cache key for each object seperately.

Example of a Caching Repository

In this example you can see the interplay between caching individual records and caching collections using CacheAllItems.

public class EmployeeCachingRepository
{

    private const string TableName = "HR.Employee";
    private const string AllCacheKey = "HR.Employee ALL";

    public IClass1DataSource Source { get; private set; }
    public CachePolicy Policy { get; private set; }

    public EmployeeCachingRepository(IClass1DataSource source, CachePolicy policy = null)
    {
        Source = source;
        Policy = policy;
    }

    protected string CacheKey(int id)
    {
        return $"HR.Employee EmployeeKey={id}";
    }

    protected string CacheKey(Employee entity)
    {
        return CacheKey(entity.EmployeeKey.Value);
    }

    public Employee Get(int id)
    {
        return Source.GetByKey(TableName, id).ToObject<Employee>().ReadOrCache(CacheKey(id), policy: Policy).Execute();
    }

    public IList<Employee> GetAll()
    {
        return Source.From(TableName).ToCollection<Employee>().CacheAllItems((Employee x) => CacheKey(x), policy: Policy).ReadOrCache(AllCacheKey, policy: Policy).Execute();
    }

    public Employee Insert(Employee entity)
    {
        return Source.Insert(TableName, entity).ToObject<Employee>().InvalidateCache(AllCacheKey).Cache((Employee x) => CacheKey(x), policy: Policy).Execute();
    }

    public Employee Update(Employee entity)
    {
        return Source.Update(TableName, entity).ToObject<Employee>().Cache(CacheKey(entity)).InvalidateCache(AllCacheKey).Execute();
    }

    public void Delete(int id)
    {
        Source.DeleteByKey(TableName, id).InvalidateCache(CacheKey(id)).InvalidateCache(AllCacheKey).Execute();
    }
}

Internals

The caching appenders use the data source to access a cache. Currently that data source is hard-coded to use .NET's built-in MemoryCache.

Roadmap

The current plan is to allow the caching framework to be swapped out.