New InMemoryCacheService implementation of ICacheService in Spark

- InMemoryCacheService cache can be used in any .net standard project
- CacheExpires class not longer has depenency on System.Web.Caching.Cache
- Renamed DefaultCacheService to WebCacheService
- Moved NullCacheService to Castle.MonoRail.Views project (it's the only place using it)
- Moved some classes back to Spark project when possible
- Moved markdown dependency back to spark

src/Castle.MonoRail.Views.Spark/Wrappers/HybridCacheService.cs

@@ -32,7 +32,7 @@ public HybridCacheService(IEngineContext context)
             }
             else
             {
-                _fallbackCacheService = new DefaultCacheService(context.UnderlyingContext.Cache);
+                _fallbackCacheService = new WebCacheService(context.UnderlyingContext.Cache);
             }
         }
 

src/Spark.Tests/InMemoryServiceTest.cs

@@ -0,0 +1,88 @@
+using System;
+using System.Threading;
+using Microsoft.Extensions.Caching.Memory;
+using NUnit.Framework;
+
+namespace Spark.Tests
+{
+    [TestFixture]
+    public class InMemoryServiceTest
+    {
+        [Test]
+        public void TestStoreValueThenRetrieveIt()
+        {
+            var service = new InMemoryCacheService(new MemoryCache(new MemoryCacheOptions()));
+
+            var item = new { };
+
+            service.Store("identifier", CacheExpires.Empty, null, item);
+
+            var retrieved = service.Get("identifier");
+
+            Assert.AreSame(item, retrieved);
+        }
+
+        [Test]
+        public void TestStoreValueThenRetrieveItAfterAbsoluteExpiration()
+        {
+            var service = new InMemoryCacheService(new MemoryCache(new MemoryCacheOptions()));
+
+            var item = new { };
+
+            service.Store("identifier", new CacheExpires(DateTime.UtcNow.AddMilliseconds(50)), null, item);
+
+            Thread.Sleep(100);
+
+            var retrieved = service.Get("identifier");
+
+            Assert.IsNull(retrieved);
+        }
+
+        [Test]
+        public void TestStoreValueThenRetrieveItWhenExpirationSlides()
+        {
+            var service = new InMemoryCacheService(new MemoryCache(new MemoryCacheOptions()));
+
+            var item = new { };
+
+            service.Store("identifier", new CacheExpires(TimeSpan.FromMilliseconds(75)), null, item);
+
+            object retrieved;
+
+            for (var i = 0; i < 3; i++)
+            {
+                Thread.Sleep(50);
+
+                retrieved = service.Get("identifier");
+            }
+
+            retrieved = service.Get("identifier");
+
+            Assert.IsNotNull(retrieved);
+
+            Assert.AreSame(item, retrieved);
+        }
+
+        [Test]
+        public void TestStoreValueWithSignal()
+        {
+            var service = new InMemoryCacheService(new MemoryCache(new MemoryCacheOptions()));
+
+            var item = new { };
+
+            var signal = new CacheSignal();
+
+            service.Store("identifier", null, signal, item);
+
+            var retrieved = service.Get("identifier");
+
+            Assert.AreSame(item, retrieved);
+
+            signal.FireChanged();
+
+            retrieved = service.Get("identifier");
+
+            Assert.IsNull(retrieved);
+        }
+    }
+}

src/Spark.Web.Mvc/Extensions/ServiceCollectionExtensions.cs

@@ -69,7 +69,7 @@ public static IServiceCollection AddSpark(this IServiceCollection services, ISpa
                 {
                     if (HttpContext.Current != null && HttpContext.Current.Cache != null)
                     {
-                        return new DefaultCacheService(HttpContext.Current.Cache);
+                        return new WebCacheService(HttpContext.Current.Cache);
                     }
 
                     return null;

src/Spark.Web.Tests/Caching/CacheElementTester.cs

@@ -553,7 +553,6 @@ public void SignalWillExpireOutputCachingEntry()
 <p>2</p>
 </div>"));
             Assert.That(calls, Is.EqualTo(2));
-
         }
     }
 }

src/Spark.Web/Spark.Web.csproj

@@ -28,9 +28,6 @@
     <Reference Include="System.Configuration" />
     <Reference Include="System.Web" />
   </ItemGroup>
-  <ItemGroup>
-    <PackageReference Include="MarkdownSharp" Version="2.0.5" />
-  </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="..\Spark\Spark.csproj" />
   </ItemGroup>

src/Spark.Web/Caching/DefaultCacheService.cs → src/Spark.Web/WebCacheService.cs

@@ -1,25 +1,25 @@
 using System;
 using System.Web.Caching;
 
-namespace Spark.Caching
+namespace Spark
 {
-    public class DefaultCacheService : ICacheService
+    public class WebCacheService : ICacheService
     {
-        private readonly Cache _cache;
+        private readonly Cache cache;
 
-        public DefaultCacheService(Cache cache)
+        public WebCacheService(Cache cache)
         {
-            _cache = cache;
+            this.cache = cache;
         }
 
         public object Get(string identifier)
         {
-            return _cache.Get(identifier);
+            return this.cache.Get(identifier);
         }
 
         public void Store(string identifier, CacheExpires expires, ICacheSignal signal, object item)
         {
-            _cache.Insert(
+            this.cache.Insert(
                 identifier,
                 item,
                 SignalDependency.For(signal),

src/Spark/CacheExpires.cs

@@ -0,0 +1,60 @@
+using System;
+
+namespace Spark
+{
+    /// <summary>
+    /// Represents when a cached entry should expire.
+    /// </summary>
+    public class CacheExpires
+    {
+        /// <summary>
+        /// Constructor for a non expiring cached entry.
+        /// </summary>
+        public CacheExpires()
+        {
+            Absolute = NoAbsoluteExpiration;
+            Sliding = NoSlidingExpiration;
+        }
+
+        /// <summary>
+        /// Constructor for a non cached entry expiring at a specified time.
+        /// </summary>
+        /// <param name="absolute">The time when to invalidate the cached entry.</param>
+        public CacheExpires(DateTime absolute)
+        {
+            Absolute = absolute;
+            Sliding = NoSlidingExpiration;
+        }
+
+        /// <summary>
+        /// Constructor for a cached entry that stays cached as long as it keeps being used.
+        /// </summary>
+        /// <param name="sliding">The timespan of sliding expirations.</param>
+        public CacheExpires(TimeSpan sliding)
+        {
+            Absolute = NoAbsoluteExpiration;
+            Sliding = sliding;
+        }
+
+        /// <summary>
+        /// Constructor for a cached entry that stays cached as long as it keeps being used.
+        /// </summary>
+        /// <param name="sliding">The number of seconds of sliding expirations.</param>
+        public CacheExpires(double sliding)
+            : this(TimeSpan.FromSeconds(sliding))
+        {
+        }
+
+        public DateTime Absolute { get; set; }
+        public TimeSpan Sliding { get; set; }
+
+        public static DateTime NoAbsoluteExpiration => DateTime.MaxValue;
+
+        public static TimeSpan NoSlidingExpiration => TimeSpan.Zero;
+
+        /// <summary>
+        /// Cached entry never to expire.
+        /// </summary>
+        public static CacheExpires Empty { get; } = new();
+    }
+}

src/Spark.Web/CacheSignal.cs → src/Spark/CacheSignal.cs

@@ -19,7 +19,7 @@ public event EventHandler Changed
                 lock (this)
                 {
                     _changed += value;
-                    if (_enabled) 
+                    if (_enabled)
                         return;
 
                     Enable();
@@ -31,7 +31,7 @@ public event EventHandler Changed
                 lock (this)
                 {
                     _changed -= value;
-                    if (_enabled != true || ChangedIsEmpty() == false) 
+                    if (_enabled != true || ChangedIsEmpty() == false)
                         return;
 
                     Disable();
@@ -42,7 +42,7 @@ public event EventHandler Changed
 
         private bool ChangedIsEmpty()
         {
-            return _changed == null || 
+            return _changed == null ||
                    _changed.GetInvocationList().Length == 0;
         }
 
@@ -52,15 +52,15 @@ private bool ChangedIsEmpty()
         /// to call FireChanged.
         /// </summary>
         protected virtual void Enable()
-        {            
+        {
         }
 
         /// <summary>
         /// Optionally implemented by descendant to tear down listening infrastructure
         /// when no cache dependencies remain listenning to the signal.
         /// </summary>
         protected virtual void Disable()
-        {            
+        {
         }
 
         /// <summary>
@@ -69,7 +69,7 @@ protected virtual void Disable()
         /// </summary>
         public void FireChanged()
         {
-            if (_changed != null) 
+            if (_changed != null)
                 _changed(this, EventArgs.Empty);
         }
     }