Avoid holding on to DependencyContext instance

Fixes #4527

src/Microsoft.AspNetCore.Mvc.Razor/Internal/DefaultRoslynCompilationService.cs

@@ -29,12 +29,12 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Internal
     /// </summary>
     public class DefaultRoslynCompilationService : ICompilationService
     {
+        private readonly IHostingEnvironment _hostingEnvironment;
         private readonly IFileProvider _fileProvider;
         private readonly Action<RoslynCompilationContext> _compilationCallback;
         private readonly CSharpParseOptions _parseOptions;
         private readonly CSharpCompilationOptions _compilationOptions;
         private readonly ILogger _logger;
-        private readonly DependencyContext _dependencyContext;
         private object _applicationReferencesLock = new object();
         private bool _applicationReferencesInitialized;
         private List<MetadataReference> _applicationReferences;
@@ -51,26 +51,12 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Internal
             IOptions<RazorViewEngineOptions> optionsAccessor,
             IRazorViewEngineFileProviderAccessor fileProviderAccessor,
             ILoggerFactory loggerFactory)
-            : this(
-                  GetDependencyContext(environment),
-                  optionsAccessor.Value,
-                  fileProviderAccessor,
-                  loggerFactory)
         {
-        }
+            _hostingEnvironment = environment;
-
-        // Internal for unit testing
-        internal DefaultRoslynCompilationService(
-            DependencyContext dependencyContext,
-            RazorViewEngineOptions viewEngineOptions,
-            IRazorViewEngineFileProviderAccessor fileProviderAccessor,
-            ILoggerFactory loggerFactory)
-        {
-            _dependencyContext = dependencyContext;
             _fileProvider = fileProviderAccessor.FileProvider;
-            _compilationCallback = viewEngineOptions.CompilationCallback;
+            _compilationCallback = optionsAccessor.Value.CompilationCallback;
-            _parseOptions = viewEngineOptions.ParseOptions;
+            _parseOptions = optionsAccessor.Value.ParseOptions;
-            _compilationOptions = viewEngineOptions.CompilationOptions;
+            _compilationOptions = optionsAccessor.Value.CompilationOptions;
             _logger = loggerFactory.CreateLogger<DefaultRoslynCompilationService>();
         }
 
@@ -165,6 +151,22 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Internal
             }
         }
 
+        /// <summary>
+        /// Gets the <see cref="DependencyContext"/>.
+        /// </summary>
+        /// <param name="hostingEnvironment">The <see cref="IHostingEnvironment"/>.</param>
+        /// <returns>The <see cref="DependencyContext"/>.</returns>
+        protected virtual DependencyContext GetDependencyContext(IHostingEnvironment hostingEnvironment)
+        {
+            if (hostingEnvironment.ApplicationName != null)
+            {
+                var applicationAssembly = Assembly.Load(new AssemblyName(hostingEnvironment.ApplicationName));
+                return DependencyContext.Load(applicationAssembly);
+            }
+
+            return null;
+        }
+
         private Assembly LoadStream(MemoryStream assemblyStream, MemoryStream pdbStream)
         {
 #if NET451
@@ -241,16 +243,17 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Internal
         private List<MetadataReference> GetApplicationReferences()
         {
             var metadataReferences = new List<MetadataReference>();
-            if (_dependencyContext == null)
+            var dependencyContext = GetDependencyContext(_hostingEnvironment);
+            if (dependencyContext == null)
             {
                 // Avoid null ref if the entry point does not have DependencyContext specified.
                 return metadataReferences;
             }
 
             var libraryPaths = new HashSet<string>(StringComparer.OrdinalIgnoreCase);
-            for (var i = 0; i < _dependencyContext.CompileLibraries.Count; i++)
+            for (var i = 0; i < dependencyContext.CompileLibraries.Count; i++)
             {
-                var library = _dependencyContext.CompileLibraries[i];
+                var library = dependencyContext.CompileLibraries[i];
                 IEnumerable<string> referencePaths;
                 try
                 {
@@ -322,16 +325,5 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Internal
                 mappedLineSpan.EndLinePosition.Line + 1,
                 mappedLineSpan.EndLinePosition.Character + 1);
         }
-
-        private static DependencyContext GetDependencyContext(IHostingEnvironment environment)
-        {
-            if (environment.ApplicationName != null)
-            {
-                var applicationAssembly = Assembly.Load(new AssemblyName(environment.ApplicationName));
-                return DependencyContext.Load(applicationAssembly);
-            }
-
-            return null;
-        }
     }
 }

test/Microsoft.AspNetCore.Mvc.Razor.Test/Internal/DefaultRoslynCompilationServiceTest.cs

@@ -4,12 +4,14 @@
 using System;
 using System.Linq;
 using System.Reflection;
+using Microsoft.AspNetCore.Hosting;
 using Microsoft.AspNetCore.Mvc.Razor.Compilation;
 using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.Text;
 using Microsoft.Extensions.DependencyModel;
 using Microsoft.Extensions.FileProviders;
 using Microsoft.Extensions.Logging.Testing;
+using Microsoft.Extensions.Options;
 using Moq;
 using Xunit;
 
@@ -24,11 +26,10 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Internal
             var content = @"
 public class MyTestType  {}";
 
-            var compilationService = new DefaultRoslynCompilationService(
+            var compilationService = new TestableRoslynCompilationService(
                 GetDependencyContext(),
                 GetOptions(),
-                GetFileProviderAccessor(),
+                GetFileProviderAccessor());
-                NullLoggerFactory.Instance);
             var relativeFileInfo = new RelativeFileInfo(
                 new TestFileInfo { PhysicalPath = "SomePath" },
                 "some-relative-path");
@@ -52,11 +53,10 @@ this should fail";
             var fileProvider = new TestFileProvider();
             var fileInfo = fileProvider.AddFile(viewPath, fileContent);
 
-            var compilationService = new DefaultRoslynCompilationService(
+            var compilationService = new TestableRoslynCompilationService(
                 GetDependencyContext(),
                 GetOptions(),
-                GetFileProviderAccessor(fileProvider),
+                GetFileProviderAccessor(fileProvider));
-                NullLoggerFactory.Instance);
             var relativeFileInfo = new RelativeFileInfo(fileInfo, "some-relative-path");
 
             // Act
@@ -77,11 +77,10 @@ this should fail";
             var fileContent = "file content";
             var content = @"this should fail";
 
-            var compilationService = new DefaultRoslynCompilationService(
+            var compilationService = new TestableRoslynCompilationService(
                 GetDependencyContext(),
                 GetOptions(),
-                GetFileProviderAccessor(),
+                GetFileProviderAccessor());
-                NullLoggerFactory.Instance);
             var relativeFileInfo = new RelativeFileInfo(
                 new TestFileInfo { Content = fileContent },
                 "some-relative-path");
@@ -113,11 +112,10 @@ this should fail";
             var fileProvider = new TestFileProvider();
             fileProvider.AddFile(path, mockFileInfo.Object);
 
-            var compilationService = new DefaultRoslynCompilationService(
+            var compilationService = new TestableRoslynCompilationService(
                 GetDependencyContext(),
                 GetOptions(),
-                GetFileProviderAccessor(),
+                GetFileProviderAccessor());
-                NullLoggerFactory.Instance);
             var relativeFileInfo = new RelativeFileInfo(mockFileInfo.Object, path);
 
             // Act
@@ -146,11 +144,10 @@ public class MyNonCustomDefinedClass {}
             var options = GetOptions();
             options.ParseOptions = options.ParseOptions.WithPreprocessorSymbols("MY_CUSTOM_DEFINE");
 
-            var compilationService = new DefaultRoslynCompilationService(
+            var compilationService = new TestableRoslynCompilationService(
                  GetDependencyContext(),
                  options,
-                 GetFileProviderAccessor(),
+                 GetFileProviderAccessor());
-                 NullLoggerFactory.Instance);
             var relativeFileInfo = new RelativeFileInfo(
                 new TestFileInfo { PhysicalPath = "SomePath" },
                 "some-relative-path");
@@ -174,11 +171,10 @@ public class MyNonCustomDefinedClass {}
             var options = new RazorViewEngineOptions();
             options.FileProviders.Add(fileProvider);
 
-            var compilationService = new DefaultRoslynCompilationService(
+            var compilationService = new TestableRoslynCompilationService(
                  GetDependencyContext(),
                  options,
-                 GetFileProviderAccessor(fileProvider),
+                 GetFileProviderAccessor(fileProvider));
-                 NullLoggerFactory.Instance);
 
             var assemblyName = "random-assembly-name";
 
@@ -261,11 +257,10 @@ public class MyNonCustomDefinedClass {}
             var content = "public class MyTestType  {}";
             RoslynCompilationContext usedCompilation = null;
 
-            var compilationService = new DefaultRoslynCompilationService(
+            var compilationService = new TestableRoslynCompilationService(
                  GetDependencyContext(),
                  GetOptions(callback: c => usedCompilation = c),
-                 GetFileProviderAccessor(),
+                 GetFileProviderAccessor());
-                 NullLoggerFactory.Instance);
 
             var relativeFileInfo = new RelativeFileInfo(
                 new TestFileInfo { PhysicalPath = "SomePath" },
@@ -283,11 +278,10 @@ public class MyNonCustomDefinedClass {}
         {
             // Arrange
             var content = "public class MyTestType  {}";
-            var compilationService = new DefaultRoslynCompilationService(
+            var compilationService = new TestableRoslynCompilationService(
                 dependencyContext: null,
                 viewEngineOptions: GetOptions(),
-                fileProviderAccessor: GetFileProviderAccessor(),
+                fileProviderAccessor: GetFileProviderAccessor());
-                loggerFactory: NullLoggerFactory.Instance);
 
             var relativeFileInfo = new RelativeFileInfo(
                 new TestFileInfo { PhysicalPath = "SomePath" },
@@ -313,11 +307,10 @@ public class MyNonCustomDefinedClass {}
                 new CompilationLibrary[0],
                 new RuntimeLibrary[0],
                 Enumerable.Empty<RuntimeFallbacks>());
-            var compilationService = new DefaultRoslynCompilationService(
+            var compilationService = new TestableRoslynCompilationService(
                 dependencyContext: dependencyContext,
                 viewEngineOptions: GetOptions(),
-                fileProviderAccessor: GetFileProviderAccessor(),
+                fileProviderAccessor: GetFileProviderAccessor());
-                loggerFactory: NullLoggerFactory.Instance);
 
             var relativeFileInfo = new RelativeFileInfo(
                 new TestFileInfo { PhysicalPath = "SomePath" },
@@ -341,11 +334,10 @@ public class MyNonCustomDefinedClass {}
                 context.Compilation = context.Compilation.RemoveAllReferences();
             });
             var content = "public class MyTestType  {}";
-            var compilationService = new DefaultRoslynCompilationService(
+            var compilationService = new TestableRoslynCompilationService(
                 dependencyContext: GetDependencyContext(),
                 viewEngineOptions: options,
-                fileProviderAccessor: GetFileProviderAccessor(),
+                fileProviderAccessor: GetFileProviderAccessor());
-                loggerFactory: NullLoggerFactory.Instance);
 
             var relativeFileInfo = new RelativeFileInfo(
                 new TestFileInfo { PhysicalPath = "SomePath" },
@@ -371,11 +363,10 @@ public class MyNonCustomDefinedClass {}
                     .AddReferences(MetadataReference.CreateFromFile(assemblyLocation));
             });
             var content = "public class MyTestType  {}";
-            var compilationService = new DefaultRoslynCompilationService(
+            var compilationService = new TestableRoslynCompilationService(
                 dependencyContext: null,
                 viewEngineOptions: options,
-                fileProviderAccessor: GetFileProviderAccessor(),
+                fileProviderAccessor: GetFileProviderAccessor());
-                loggerFactory: NullLoggerFactory.Instance);
 
             var relativeFileInfo = new RelativeFileInfo(
                 new TestFileInfo { PhysicalPath = "SomePath" },
@@ -422,5 +413,33 @@ public class MyNonCustomDefinedClass {}
             var assembly = typeof(DefaultRoslynCompilationServiceTest).GetTypeInfo().Assembly;
             return DependencyContext.Load(assembly);
         }
+
+        private class TestableRoslynCompilationService : DefaultRoslynCompilationService
+        {
+            private readonly DependencyContext _dependencyContext;
+
+            public TestableRoslynCompilationService(
+                DependencyContext dependencyContext,
+                RazorViewEngineOptions viewEngineOptions,
+                IRazorViewEngineFileProviderAccessor fileProviderAccessor)
+                : base(
+                      Mock.Of<IHostingEnvironment>(),
+                      GetAccessor(viewEngineOptions),
+                      fileProviderAccessor,
+                      NullLoggerFactory.Instance)
+            {
+                _dependencyContext = dependencyContext;
+            }
+
+            private static IOptions<RazorViewEngineOptions> GetAccessor(RazorViewEngineOptions options)
+            {
+                var optionsAccessor = new Mock<IOptions<RazorViewEngineOptions>>();
+                optionsAccessor.SetupGet(a => a.Value).Returns(options);
+                return optionsAccessor.Object;
+            }
+
+            protected override DependencyContext GetDependencyContext(IHostingEnvironment hostingEnvironment)
+                => _dependencyContext;
+        }
     }
 }