Feature list not refreshed when adding a new module

Update cache manager to rely on a thread static variable to
keep track of nested calls to ICacheManager.Get().

This fixes this particular bug of IExtensionManager caching the list
of available features: instead of storing the result of the computation
in a field (which is incorrect), use the cache manager.

Work Items: 16867

--HG--
branch : dev

src/Orchard/Caching/AcquireContext.cs

@@ -1,7 +1,11 @@
 using System;
 
 namespace Orchard.Caching {
-    public class AcquireContext<TKey> {
+    public interface IAcquireContext {
+        Action<IVolatileToken> Monitor { get; }
+    }
+
+    public class AcquireContext<TKey> : IAcquireContext {
         public AcquireContext(TKey key, Action<IVolatileToken> monitor) {
             Key = key;
             Monitor = monitor;

src/Orchard/Caching/Cache.cs

@@ -17,13 +17,33 @@ namespace Orchard.Caching {
                 k => CreateEntry(k, acquire),
                 // "Update" lamdba
                 (k, currentEntry) => (currentEntry.Tokens.All(t => t.IsCurrent) ? currentEntry : CreateEntry(k, acquire)));
+
+            // Bubble up volatile tokens to parent context
+            if (CacheAquireContext.ThreadInstance != null) {
+                foreach (var token in entry.Tokens)
+                    CacheAquireContext.ThreadInstance.Monitor(token);
+            }
+
             return entry.Result;
         }
 
+
         private static CacheEntry CreateEntry(TKey k, Func<AcquireContext<TKey>, TResult> acquire) {
             var entry = new CacheEntry { Tokens = new List<IVolatileToken>() };
             var context = new AcquireContext<TKey>(k, volatileItem => entry.Tokens.Add(volatileItem));
-            entry.Result = acquire(context);
+
+            IAcquireContext parentContext = null;
+            try {
+                // Push context
+                parentContext = CacheAquireContext.ThreadInstance;
+                CacheAquireContext.ThreadInstance = context;
+
+                entry.Result = acquire(context);
+            }
+            finally {
+                // Pop context
+                CacheAquireContext.ThreadInstance = parentContext;
+            }
             return entry;
         }
 
@@ -32,4 +52,12 @@ namespace Orchard.Caching {
             public IList<IVolatileToken> Tokens { get; set; }
         }
     }
+
+    /// <summary>
+    /// Keep track of nested caches contexts on a given thread
+    /// </summary>
+    internal static class CacheAquireContext {
+        [ThreadStatic]
+        public static IAcquireContext ThreadInstance;
+    }
 }

src/Orchard/Environment/Extensions/ExtensionManager.cs

@@ -1,7 +1,6 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
-using System.Web;
 using Orchard.Caching;
 using Orchard.Environment.Extensions.Folders;
 using Orchard.Environment.Extensions.Loaders;
@@ -16,7 +15,6 @@ namespace Orchard.Environment.Extensions {
         private readonly IEnumerable<IExtensionFolders> _folders;
         private readonly ICacheManager _cacheManager;
         private readonly IEnumerable<IExtensionLoader> _loaders;
-        private IEnumerable<FeatureDescriptor> _featureDescriptors;
 
         public Localizer T { get; set; }
         public ILogger Logger { get; set; }
@@ -40,11 +38,8 @@ namespace Orchard.Environment.Extensions {
         }
 
         public IEnumerable<FeatureDescriptor> AvailableFeatures() {
-            if (_featureDescriptors == null || _featureDescriptors.Count() == 0) {
-                _featureDescriptors = AvailableExtensions().SelectMany(ext => ext.Features).OrderByDependencies(HasDependency).ToReadOnlyCollection();
-                return _featureDescriptors;
-            }
-            return _featureDescriptors;
+            return _cacheManager.Get("...", ctx => 
+                AvailableExtensions().SelectMany(ext => ext.Features).OrderByDependencies(HasDependency).ToReadOnlyCollection());
         }
 
         /// <summary>

src/Orchard/Environment/Extensions/Folders/ExtensionFolders.cs

@@ -47,7 +47,6 @@ namespace Orchard.Environment.Extensions.Folders {
                     foreach (var subfolderPath in subfolderPaths) {
                         var extensionId = Path.GetFileName(subfolderPath.TrimEnd('/', '\\'));
                         var manifestPath = Path.Combine(subfolderPath, _manifestName);
-                        ctx.Monitor(_webSiteFolder.WhenPathChanges(manifestPath));
                         try {
                             var descriptor = GetExtensionDescriptor(path, extensionId, manifestPath);
                             if (descriptor != null)

src/Orchard/FileSystems/VirtualPath/DefaultVirtualPathMonitor.cs

@@ -89,6 +89,10 @@ namespace Orchard.FileSystems.VirtualPath {
             }
             public bool IsCurrent { get; set; }
             public string VirtualPath { get; private set; }
+
+            public override string ToString() {
+                return string.Format("IsCurrent: {0}, VirtualPath: \"{1}\"", IsCurrent, VirtualPath);
+            }
         }
 
         class Thunk {