Feature/5790 participate in cache key generation

src/Orchard.Web/Modules/Orchard.OutputCache/Filters/OutputCacheFilter.cs

@@ -41,6 +41,7 @@ public class OutputCacheFilter : FilterProvider, IActionFilter, IResultFilter, I
         private readonly ICacheService _cacheService;
         private readonly ISignals _signals;
         private readonly ShellSettings _shellSettings;
+        private readonly ICachingEventHandler _cachingEvents;
         private bool _isDisposed = false;
 
         public ILogger Logger { get; set; }
@@ -55,7 +56,8 @@ public OutputCacheFilter(
             IClock clock,
             ICacheService cacheService,
             ISignals signals,
-            ShellSettings shellSettings) {
+            ShellSettings shellSettings,
+            ICachingEventHandler cachingEvents) {
 
             _cacheManager = cacheManager;
             _cacheStorageProvider = cacheStorageProvider;
@@ -67,6 +69,7 @@ public OutputCacheFilter(
             _cacheService = cacheService;
             _signals = signals;
             _shellSettings = shellSettings;
+            _cachingEvents = cachingEvents;
 
             Logger = NullLogger.Instance;
         }
@@ -610,6 +613,9 @@ protected virtual string ComputeCacheKey(string tenant, string absoluteUrl, IEnu
                 }
             }
 
+            //make CacheKey morphable by external modules
+            _cachingEvents.KeyGenerated(keyBuilder);
+
             return keyBuilder.ToString();
         }
 

src/Orchard.Web/Modules/Orchard.OutputCache/ICachingEventHandler.cs

@@ -0,0 +1,12 @@
+using Orchard.Events;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Web;
+
+namespace Orchard.OutputCache {
+    public interface ICachingEventHandler : IEventHandler {
+        void KeyGenerated(StringBuilder key);
+    }
+}

src/Orchard.Web/Modules/Orchard.OutputCache/Orchard.OutputCache.csproj

@@ -103,6 +103,7 @@
     <Content Include="Web.config" />
     <Content Include="Scripts\Web.config" />
     <Content Include="Styles\Web.config" />
+    <Compile Include="ICachingEventHandler.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
     <Content Include="Module.txt" />
   </ItemGroup>