Redesign RazorViewEngine caching

Fixes #3337

src/Microsoft.AspNet.Mvc.Razor/Compilation/CompilerCache.cs

@@ -8,6 +8,7 @@
 using System.Text;
 using Microsoft.AspNet.FileProviders;
 using Microsoft.Extensions.Caching.Memory;
+using Microsoft.Extensions.Primitives;
 
 namespace Microsoft.AspNet.Mvc.Razor.Compilation
 {
@@ -54,9 +55,10 @@ public CompilerCache(
                 throw new ArgumentNullException(nameof(precompiledViews));
             }
 
+            var expirationTokens = new IChangeToken[0];
             foreach (var item in precompiledViews)
             {
-                var cacheEntry = new CompilerCacheResult(CompilationResult.Successful(item.Value));
+                var cacheEntry = new CompilerCacheResult(CompilationResult.Successful(item.Value), expirationTokens);
                 _cache.Set(GetNormalizedPath(item.Key), cacheEntry);
             }
         }
@@ -95,17 +97,18 @@ private CompilerCacheResult CreateCacheEntry(
             string normalizedPath,
             Func<RelativeFileInfo, CompilationResult> compile)
         {
-            CompilerCacheResult cacheResult;
             var fileInfo = _fileProvider.GetFileInfo(normalizedPath);
             MemoryCacheEntryOptions cacheEntryOptions;
+            CompilerCacheResult cacheResult;
             CompilerCacheResult cacheResultToCache;
             if (!fileInfo.Exists)
             {
-                cacheResultToCache = CompilerCacheResult.FileNotFound;
-                cacheResult = CompilerCacheResult.FileNotFound;
+                var expirationToken = _fileProvider.Watch(normalizedPath);
+                cacheResult = new CompilerCacheResult(new[] { expirationToken });
+                cacheResultToCache = cacheResult;
 
                 cacheEntryOptions = new MemoryCacheEntryOptions();
-                cacheEntryOptions.AddExpirationToken(_fileProvider.Watch(normalizedPath));
+                cacheEntryOptions.AddExpirationToken(expirationToken);
             }
             else
             {
@@ -117,8 +120,11 @@ private CompilerCacheResult CreateCacheEntry(
                 // UncachedCompilationResult. This type has the generated code as a string property and do not want
                 // to cache it. We'll instead cache the unwrapped result.
                 cacheResultToCache = new CompilerCacheResult(
-                    CompilationResult.Successful(compilationResult.CompiledType));
-                cacheResult = new CompilerCacheResult(compilationResult);
+                    CompilationResult.Successful(compilationResult.CompiledType),
+                    cacheEntryOptions.ExpirationTokens);
+                cacheResult = new CompilerCacheResult(
+                    compilationResult,
+                    cacheEntryOptions.ExpirationTokens);
             }
 
             _cache.Set(normalizedPath, cacheResultToCache, cacheEntryOptions);

src/Microsoft.AspNet.Mvc.Razor/Compilation/CompilerCacheResult.cs

@@ -2,6 +2,8 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
+using System.Collections.Generic;
+using Microsoft.Extensions.Primitives;
 
 namespace Microsoft.AspNet.Mvc.Razor.Compilation
 {
@@ -10,38 +12,46 @@ namespace Microsoft.AspNet.Mvc.Razor.Compilation
     /// </summary>
     public class CompilerCacheResult
     {
-        /// <summary>
-        /// Result of <see cref="ICompilerCache"/> when the specified file does not exist in the
-        /// file system.
-        /// </summary>
-        public static CompilerCacheResult FileNotFound { get; } = new CompilerCacheResult();
-
         /// <summary>
         /// Initializes a new instance of <see cref="CompilerCacheResult"/> with the specified
         /// <see cref="CompilationResult"/>.
         /// </summary>
         /// <param name="compilationResult">The <see cref="Compilation.CompilationResult"/> </param>
-        public CompilerCacheResult(CompilationResult compilationResult)
+        public CompilerCacheResult(CompilationResult compilationResult, IList<IChangeToken> expirationTokens)
         {
             if (compilationResult == null)
             {
                 throw new ArgumentNullException(nameof(compilationResult));
             }
 
+            if (expirationTokens == null)
+            {
+                throw new ArgumentNullException(nameof(expirationTokens));
+            }
+
             CompilationResult = compilationResult;
+            ExpirationTokens = expirationTokens;
         }
 
-        /// <summary>
-        /// Initializes a new instance of <see cref="CompilerCacheResult"/> for a failed file lookup.
-        /// </summary>
-        protected CompilerCacheResult()
+        public CompilerCacheResult(IList<IChangeToken> expirationTokens)
         {
+            if (expirationTokens == null)
+            {
+                throw new ArgumentNullException(nameof(expirationTokens));
+            }
+
+            CompilationResult = null;
+            ExpirationTokens = expirationTokens;
         }
 
         /// <summary>
         /// The <see cref="Compilation.CompilationResult"/>.
         /// </summary>
         /// <remarks>This property is null when file lookup failed.</remarks>
         public CompilationResult CompilationResult { get; }
+
+        public IList<IChangeToken> ExpirationTokens { get; }
+
+        public bool IsFoundResult => CompilationResult != null;
     }
 }

src/Microsoft.AspNet.Mvc.Razor/VirtualPathRazorPageFactory.cs → src/Microsoft.AspNet.Mvc.Razor/DefaultRazorPageFactory.cs

@@ -10,7 +10,7 @@ namespace Microsoft.AspNet.Mvc.Razor
     /// Represents a <see cref="IRazorPageFactory"/> that creates <see cref="RazorPage"/> instances
     /// from razor files in the file system.
     /// </summary>
-    public class VirtualPathRazorPageFactory : IRazorPageFactory
+    public class DefaultRazorPageFactory : IRazorPageFactory
     {
         /// <remarks>
         /// This delegate holds on to an instance of <see cref="IRazorCompilationService"/>.
@@ -24,7 +24,7 @@ public class VirtualPathRazorPageFactory : IRazorPageFactory
         /// </summary>
         /// <param name="razorCompilationService">The <see cref="IRazorCompilationService"/>.</param>
         /// <param name="compilerCacheProvider">The <see cref="ICompilerCacheProvider"/>.</param>
-        public VirtualPathRazorPageFactory(
+        public DefaultRazorPageFactory(
             IRazorCompilationService razorCompilationService,
             ICompilerCacheProvider compilerCacheProvider)
         {
@@ -46,7 +46,7 @@ private ICompilerCache CompilerCache
         }
 
         /// <inheritdoc />
-        public IRazorPage CreateInstance(string relativePath)
+        public RazorPageFactoryResult CreateFactory(string relativePath)
         {
             if (relativePath == null)
             {
@@ -58,18 +58,20 @@ public IRazorPage CreateInstance(string relativePath)
                 // For tilde slash paths, drop the leading ~ to make it work with the underlying IFileProvider.
                 relativePath = relativePath.Substring(1);
             }
-
             var result = CompilerCache.GetOrAdd(relativePath, _compileDelegate);
-
-            if (result == CompilerCacheResult.FileNotFound)
+            if (result.IsFoundResult)
             {
-                return null;
+                return new RazorPageFactoryResult(() =>
+                {
+                    var page = (IRazorPage)Activator.CreateInstance(result.CompilationResult.CompiledType);
+                    page.Path = relativePath;
+                    return page;
+                }, result.ExpirationTokens);
+            }
+            else
+            {
+                return new RazorPageFactoryResult(result.ExpirationTokens);
             }
-
-            var page = (IRazorPage)Activator.CreateInstance(result.CompilationResult.CompiledType);
-            page.Path = relativePath;
-
-            return page;
         }
     }
 }

src/Microsoft.AspNet.Mvc.Razor/DependencyInjection/MvcRazorMvcCoreBuilderExtensions.cs

@@ -131,8 +131,6 @@ internal static void AddRazorViewEngineServices(IServiceCollection services)
 
             services.TryAddSingleton<IRazorViewEngine, RazorViewEngine>();
 
-            // Caches view locations that are valid for the lifetime of the application.
-            services.TryAddSingleton<IViewLocationCache, DefaultViewLocationCache>();
             services.TryAdd(ServiceDescriptor.Singleton<IChunkTreeCache>(serviceProvider =>
             {
                 var cachedFileProvider = serviceProvider.GetRequiredService<IOptions<RazorViewEngineOptions>>();
@@ -148,9 +146,8 @@ internal static void AddRazorViewEngineServices(IServiceCollection services)
             // In the default scenario the following services are singleton by virtue of being initialized as part of
             // creating the singleton RazorViewEngine instance.
             services.TryAddTransient<IRazorViewFactory, RazorViewFactory>();
-            services.TryAddTransient<IRazorPageFactory, VirtualPathRazorPageFactory>();
+            services.TryAddTransient<IRazorPageFactory, DefaultRazorPageFactory>();
             services.TryAddTransient<IRazorCompilationService, RazorCompilationService>();
-            services.TryAddTransient<IViewStartProvider, ViewStartProvider>();
             services.TryAddTransient<IMvcRazorHost, MvcRazorHost>();
 
             // This caches Razor page activation details that are valid for the lifetime of the application.

src/Microsoft.AspNet.Mvc.Razor/IRazorPageFactory.cs

@@ -9,10 +9,10 @@ namespace Microsoft.AspNet.Mvc.Razor
     public interface IRazorPageFactory
     {
         /// <summary>
-        /// Creates a <see cref="IRazorPage"/> for the specified path.
+        /// Creates a <see cref="IRazorPage"/> factory for the specified path.
         /// </summary>
         /// <param name="relativePath">The path to locate the page.</param>
-        /// <returns>The IRazorPage instance if it exists, null otherwise.</returns>
-        IRazorPage CreateInstance(string relativePath);
+        /// <returns>The <see cref="RazorPageFactoryResult"/> instance.</returns>
+        RazorPageFactoryResult CreateFactory(string relativePath);
     }
 }