README.md

EF Core 3.1.x, 5.x & 6.x Second Level Cache Interceptor

Second level caching is a query cache. The results of EF commands will be stored in the cache, so that the same EF commands will retrieve their data from the cache rather than executing them against the database again.

Install via NuGet

To install EFCoreSecondLevelCacheInterceptor, run the following command in the Package Manager Console:

PM> Install-Package EFCoreSecondLevelCacheInterceptor

You can also view the package page on NuGet.

Usage (1 & 2 are mandatory)

1- Register a preferred cache provider:

Using the built-in In-Memory cache provider

namespace EFCoreSecondLevelCacheInterceptor.AspNetCoreSample
{
    public class Startup
    {
        private readonly string _contentRootPath;

        public Startup(IConfiguration configuration, IWebHostEnvironment env)
        {
            _contentRootPath = env.ContentRootPath;
            Configuration = configuration;
        }

        public IConfiguration Configuration { get; }

        public void ConfigureServices(IServiceCollection services)
        {
            services.AddEFSecondLevelCache(options =>
                options.UseMemoryCacheProvider().DisableLogging(true)

            // Please use the `CacheManager.Core` or `EasyCaching.Redis` for the Redis cache provider.
            );

            var connectionString = Configuration["ConnectionStrings:ApplicationDbContextConnection"];
            if (connectionString.Contains("%CONTENTROOTPATH%"))
            {
                connectionString = connectionString.Replace("%CONTENTROOTPATH%", _contentRootPath);
            }
            services.AddConfiguredMsSqlDbContext(connectionString);

            services.AddControllersWithViews();
        }
    }
}

Using EasyCaching.Core as the cache provider

Here you can use the EasyCaching.Core, as a highly configurable cache manager too. To use its in-memory caching mechanism, add this entry to the .csproj file:

  <ItemGroup>
    <PackageReference Include="EasyCaching.InMemory" Version="1.1.0" />
  </ItemGroup>

Then register its required services:

namespace EFSecondLevelCache.Core.AspNetCoreSample
{
    public class Startup
    {
        public void ConfigureServices(IServiceCollection services)
        {
            const string providerName1 = "InMemory1";
            services.AddEFSecondLevelCache(options =>
                    options.UseEasyCachingCoreProvider(providerName1, isHybridCache: false).DisableLogging(true)
            );

            // Add an in-memory cache service provider
            // More info: https://easycaching.readthedocs.io/en/latest/In-Memory/
            services.AddEasyCaching(options =>
            {
                // use memory cache with your own configuration
                options.UseInMemory(config =>
                {
                    config.DBConfig = new InMemoryCachingOptions
                    {
                        // scan time, default value is 60s
                        ExpirationScanFrequency = 60,
                        // total count of cache items, default value is 10000
                        SizeLimit = 100,

                        // enable deep clone when reading object from cache or not, default value is true.
                        EnableReadDeepClone = false,
                        // enable deep clone when writing object to cache or not, default value is false.
                        EnableWriteDeepClone = false,
                    };
                    // the max random second will be added to cache's expiration, default value is 120
                    config.MaxRdSecond = 120;
                    // whether enable logging, default is false
                    config.EnableLogging = false;
                    // mutex key's alive time(ms), default is 5000
                    config.LockMs = 5000;
                    // when mutex key alive, it will sleep some time, default is 300
                    config.SleepMs = 300;
                }, providerName1);
            });
        }
    }
}

If you want to use the Redis as the preferred cache provider with EasyCaching.Core, first install the following package:

  <ItemGroup>
    <PackageReference Include="EasyCaching.Redis" Version="1.1.0" />
  </ItemGroup>

And then register its required services:

namespace EFSecondLevelCache.Core.AspNetCoreSample
{
    public class Startup
    {
        public void ConfigureServices(IServiceCollection services)
        {
            const string providerName1 = "Redis1";
            services.AddEFSecondLevelCache(options =>
                    options.UseEasyCachingCoreProvider(providerName1, isHybridCache: false).DisableLogging(true)
            );

            // More info: https://easycaching.readthedocs.io/en/latest/Redis/
            services.AddEasyCaching(option =>
            {
                option.UseRedis(config =>
                {
                    config.DBConfig.AllowAdmin = true;
                    config.DBConfig.SyncTimeout = 10000;
                    config.DBConfig.AsyncTimeout = 10000;
                    config.DBConfig.Endpoints.Add(new EasyCaching.Core.Configurations.ServerEndPoint("127.0.0.1", 6379));
                }, providerName1);
            });
        }
    }
}

Using CacheManager.Core as the cache provider [It's not actively maintained]

Also here you can use the CacheManager.Core, as a highly configurable cache manager too. To use its in-memory caching mechanism, add these entries to the .csproj file:

  <ItemGroup>
    <PackageReference Include="CacheManager.Core" Version="1.2.0" />
    <PackageReference Include="CacheManager.Microsoft.Extensions.Caching.Memory" Version="1.2.0" />
    <PackageReference Include="CacheManager.Serialization.Json" Version="1.2.0" />
  </ItemGroup>

Then register its required services:

namespace EFSecondLevelCache.Core.AspNetCoreSample
{
    public class Startup
    {
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddEFSecondLevelCache(options =>
                options.UseCacheManagerCoreProvider().DisableLogging(true)
            );

            // Add an in-memory cache service provider
            services.AddSingleton(typeof(ICacheManager<>), typeof(BaseCacheManager<>));
            services.AddSingleton(typeof(ICacheManagerConfiguration),
                new CacheManager.Core.ConfigurationBuilder()
                        .WithJsonSerializer()
                        .WithMicrosoftMemoryCacheHandle(instanceName: "MemoryCache1")
                        .Build());
        }
    }
}

If you want to use the Redis as the preferred cache provider with CacheManager.Core, first install the CacheManager.StackExchange.Redis package and then register its required services:

// Add Redis cache service provider
var jss = new JsonSerializerSettings
{
    NullValueHandling = NullValueHandling.Ignore,
    ReferenceLoopHandling = ReferenceLoopHandling.Ignore,
    TypeNameHandling = TypeNameHandling.Auto,
    Converters = { new SpecialTypesConverter() }
};

const string redisConfigurationKey = "redis";
services.AddSingleton(typeof(ICacheManagerConfiguration),
    new CacheManager.Core.ConfigurationBuilder()
        .WithJsonSerializer(serializationSettings: jss, deserializationSettings: jss)
        .WithUpdateMode(CacheUpdateMode.Up)
        .WithRedisConfiguration(redisConfigurationKey, config =>
        {
            config.WithAllowAdmin()
                .WithDatabase(0)
                .WithEndpoint("localhost", 6379)
                // Enables keyspace notifications to react on eviction/expiration of items.
                // Make sure that all servers are configured correctly and 'notify-keyspace-events' is at least set to 'Exe', otherwise CacheManager will not retrieve any events.
                // You can try 'Egx' or 'eA' value for the `notify-keyspace-events` too.
                // See https://redis.io/topics/notifications#configuration for configuration details.
                .EnableKeyspaceEvents();
        })
        .WithMaxRetries(100)
        .WithRetryTimeout(50)
        .WithRedisCacheHandle(redisConfigurationKey)
        .Build());
services.AddSingleton(typeof(ICacheManager<>), typeof(BaseCacheManager<>));

services.AddEFSecondLevelCache(options =>
    options.UseCacheManagerCoreProvider().DisableLogging(true)
);

Here is the definition of the SpecialTypesConverter.

Using a custom cache provider

If you don't want to use the above cache providers, implement your custom IEFCacheServiceProvider and then introduce it using the options.UseCustomCacheProvider<T>() method.

2- Add SecondLevelCacheInterceptor to your DbContextOptionsBuilder pipeline:

    public static class MsSqlServiceCollectionExtensions
    {
        public static IServiceCollection AddConfiguredMsSqlDbContext(this IServiceCollection services, string connectionString)
        {
            services.AddDbContextPool<ApplicationDbContext>((serviceProvider, optionsBuilder) =>
                    optionsBuilder
                        .UseSqlServer(
                            connectionString,
                            sqlServerOptionsBuilder =>
                            {
                                sqlServerOptionsBuilder
                                    .CommandTimeout((int)TimeSpan.FromMinutes(3).TotalSeconds)
                                    .EnableRetryOnFailure()
                                    .MigrationsAssembly(typeof(MsSqlServiceCollectionExtensions).Assembly.FullName);
                            })
                        .AddInterceptors(serviceProvider.GetRequiredService<SecondLevelCacheInterceptor>()));
            return services;
        }
    }

3- Setting up the cache invalidation:

This library doesn't need any settings for the cache invalidation. It watches for all of the CRUD operations using its interceptor and then invalidates the related cache entries automatically. But if you want to invalidate the whole cache manually, inject the IEFCacheServiceProvider service and then call its ClearAllCachedEntries() method.

4- To cache the results of the normal queries like:

var post1 = context.Posts
                   .Where(x => x.Id > 0)
                   .OrderBy(x => x.Id)
                   .FirstOrDefault();

We can use the new Cacheable() extension method:

var post1 = context.Posts
                   .Where(x => x.Id > 0)
                   .OrderBy(x => x.Id)
                   .Cacheable(CacheExpirationMode.Sliding, TimeSpan.FromMinutes(5))
                   .FirstOrDefault();  // Async methods are supported too.

NOTE: It doesn't matter where the Cacheable method is located in this expression tree. It just adds the standard TagWith method to mark this query as Cacheable. Later SecondLevelCacheInterceptor will use this tag to identify the Cacheable queries.

Also it's possible to set the Cacheable() method's settings globally:

services.AddEFSecondLevelCache(options => options.UseMemoryCacheProvider(CacheExpirationMode.Absolute, TimeSpan.FromMinutes(5)).DisableLogging(true));

In this case the above query will become:

var post1 = context.Posts
                   .Where(x => x.Id > 0)
                   .OrderBy(x => x.Id)
                   .Cacheable()
                   .FirstOrDefault();  // Async methods are supported too.

If you specify the settings of the Cacheable() method explicitly such as Cacheable(CacheExpirationMode.Sliding, TimeSpan.FromMinutes(5)), its setting will override the global setting.

Caching all of the queries

To cache all of the system's queries, just set the CacheAllQueries() method:

namespace EFCoreSecondLevelCacheInterceptor.AspNetCoreSample
{
    public class Startup
    {
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddEFSecondLevelCache(options =>
            {
                options.UseMemoryCacheProvider().DisableLogging(true);
                options.CacheAllQueries(CacheExpirationMode.Absolute, TimeSpan.FromMinutes(30));
            });

            // ...

This will put the whole system's queries in cache. In this case calling the Cacheable() methods won't be necessary. If you specify the Cacheable() method, its setting will override this global setting. If you want to exclude some of the queries from this global cache, apply the NotCacheable() method to them.

Caching some of the queries

To cache some of the system's queries based on their entity-types or table-names, use CacheQueriesContainingTypes or CacheQueriesContainingTableNames methods:

namespace EFCoreSecondLevelCacheInterceptor.AspNetCoreSample
{
    public class Startup
    {
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddEFSecondLevelCache(options =>
            {
                options.UseMemoryCacheProvider().DisableLogging(true)
                    /*.CacheQueriesContainingTypes(
                        CacheExpirationMode.Absolute, TimeSpan.FromMinutes(30),
                        typeof(Post), typeof(Product), typeof(User)
                        )*/
                    .CacheQueriesContainingTableNames(
                        CacheExpirationMode.Absolute, TimeSpan.FromMinutes(30),
                        "posts", "products", "users"
                        );
            });

            // ...

This will put the the specified system's queries in cache. In this case calling the Cacheable() methods won't be necessary. If you specify the Cacheable() method, its setting will override this global setting. If you want to exclude some of the queries from this global cache, apply the NotCacheable() method to them.

Skip caching of some of the queries

To skip caching some of the system's queries based on their SQL commands, set the SkipCachingCommands predicate:

namespace EFCoreSecondLevelCacheInterceptor.AspNetCoreSample
{
    public class Startup
    {
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddEFSecondLevelCache(options =>
            {
                options.UseMemoryCacheProvider().DisableLogging(true)
                        // How to skip caching specific commands
                       .SkipCachingCommands(commandText =>
                                commandText.Contains("NEWID()", StringComparison.InvariantCultureIgnoreCase));
            });
            // ...

Skip caching of some of the queries based on their results

To skip caching some of the system's queries based on their results, set the SkipCachingResults predicate:

namespace EFCoreSecondLevelCacheInterceptor.AspNetCoreSample
{
    public class Startup
    {
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddEFSecondLevelCache(options =>
            {
                options.UseMemoryCacheProvider().DisableLogging(true)
                        // Don't cache null values. Remove this optional setting if it's not necessary.
                        .SkipCachingResults(result =>
                                result.Value == null || (result.Value is EFTableRows rows && rows.RowsCount == 0));
            });
            // ...

Skip caching some of the queries based on their table names

To do not cache some of the system's queries based on their entity-types or table-names, use CacheAllQueriesExceptContainingTypes or CacheAllQueriesExceptContainingTableNames methods:

namespace EFCoreSecondLevelCacheInterceptor.AspNetCoreSample
{
    public class Startup
    {
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddEFSecondLevelCache(options =>
            {
                options.UseMemoryCacheProvider().DisableLogging(true)
                    /*.CacheAllQueriesExceptContainingTypes(
                        CacheExpirationMode.Absolute, TimeSpan.FromMinutes(30),
                        typeof(Post), typeof(Product), typeof(User)
                        )*/
                    .CacheAllQueriesExceptContainingTableNames(
                        CacheExpirationMode.Absolute, TimeSpan.FromMinutes(30),
                        "posts", "products", "users"
                        );
            });

            // ...

This will not put the the specified system's queries in cache. In this case calling the Cacheable() methods won't be necessary. If you specify the Cacheable() method, its setting will override this global setting.

Skip invalidating the related cache entries of a given query

Sometimes you don't want to invalidate the cache immediately, such when you are updating a post's likes or views count. In this case to skip invalidating the related cache entries of a given CRUD command, set the SkipCacheInvalidationCommands predicate:

namespace EFCoreSecondLevelCacheInterceptor.AspNetCoreSample
{
    public class Startup
    {
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddEFSecondLevelCache(options =>
            {
                options.UseMemoryCacheProvider().DisableLogging(true)
                    .SkipCacheInvalidationCommands(commandText =>
                                // How to skip invalidating the related cache entries of this query
                                commandText.Contains("NEWID()", StringComparison.InvariantCultureIgnoreCase));
            });
            // ...

Does it work?!

You should enable the logging system to see the behind the scene of the caching interceptor. First set the DisableLogging(false):

 services.AddEFSecondLevelCache(options =>
                options.UseMemoryCacheProvider().DisableLogging(false)

And then change the log level to Debug in your appsettings.json file:

{
  "Logging": {
    "LogLevel": {
      "Default": "Debug",
      "System": "Debug",
      "Microsoft": "Debug",
      "Microsoft.Hosting.Lifetime": "Debug"
    }
  }
}

Now after running a query multiple times, you should have these logged lines:

Suppressed result with a TableRows[ee20d2d7-ffc7-4ff9-9484-e8d4eecde53e] from the cache[KeyHash: EB153BD4, CacheDependencies: Page.].
Using the TableRows[ee20d2d7-ffc7-4ff9-9484-e8d4eecde53e] from the cache.

Notes:

• Having the Suppressed the result with the TableRows message means the caching interceptor is working fine.
• The next Executed DbCommand means nothing and it always will be logged by EF.
• At the beginning there will be a lot of internal commands executed by the EF to run migrations, etc. Ignore these commands, because you will see the Suppressed the result with the TableRows messages for the frequently running queries.
• Also you should verify it with a real DB profiler. It will log the 1st executed query and then on the 2nd run, you won't see it anymore.

Samples

• Console App Sample
• ASP.NET Core App Sample
• Tests

Guidance

When to use

Good candidates for query caching are global site settings and public data, such as infrequently changing articles or comments. It can also be beneficial to cache data specific to a user so long as the cache expires frequently enough relative to the size of the user base that memory consumption remains acceptable. Small, per-user data that frequently exceeds the cache's lifetime, such as a user's photo path, is better held in user claims, which are stored in cookies, than in this cache.

Scope

This cache is scoped to the application, not the current user. It does not use session variables. Accordingly, when retrieving cached per-user data, be sure queries in include code such as .Where(x => .... && x.UserId == id).

Invalidation

This cache is updated when an entity is changed (insert, update, or delete) via a DbContext that uses this library. If the database is updated through some other means, such as a stored procedure or trigger, the cache becomes stale.