Log diagnostic info about search for localization resources

src/Microsoft.Extensions.Localization.Abstractions/LocalizedString.cs

@@ -27,6 +27,18 @@ public LocalizedString(string name, string value)
         /// <param name="value">The actual string.</param>
         /// <param name="resourceNotFound">Whether the string was not found in a resource. Set this to <c>true</c> to indicate an alternate string value was used.</param>
         public LocalizedString(string name, string value, bool resourceNotFound)
+            : this(name, value, resourceNotFound, searchedLocation: null)
+        {
+        }
+
+        /// <summary>
+        /// Creates a new <see cref="LocalizedString"/>.
+        /// </summary>
+        /// <param name="name">The name of the string in the resource it was loaded from.</param>
+        /// <param name="value">The actual string.</param>
+        /// <param name="resourceNotFound">Whether the string was not found in a resource. Set this to <c>true</c> to indicate an alternate string value was used.</param>
+        /// <param name="searchedLocation">The location which was searched for a localization value.</param>
+        public LocalizedString(string name, string value, bool resourceNotFound, string searchedLocation)
         {
             if (name == null)
             {
@@ -41,6 +53,7 @@ public LocalizedString(string name, string value, bool resourceNotFound)
             Name = name;
             Value = value;
             ResourceNotFound = resourceNotFound;
+            SearchedLocation = searchedLocation;
         }
 
         public static implicit operator string(LocalizedString localizedString)
@@ -63,6 +76,11 @@ public static implicit operator string(LocalizedString localizedString)
         /// </summary>
         public bool ResourceNotFound { get; }
 
+        /// <summary>
+        /// The location which was searched for a localization value.
+        /// </summary>
+        public string SearchedLocation { get; }
+
         /// <summary>
         /// Returns the actual string.
         /// </summary>

src/Microsoft.Extensions.Localization/Internal/ResourceManagerStringLocalizerLoggerExtensions.cs

@@ -0,0 +1,27 @@
+// Copyright (c) .NET Foundation. All rights reserved. 
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information. 
+
+using System;
+using System.Globalization;
+using Microsoft.Extensions.Logging;
+
+namespace Microsoft.Extensions.Localization.Internal
+{
+    internal static class ResourceManagerStringLocalizerLoggerExtensions
+    {
+        private static readonly Action<ILogger, string, string, CultureInfo, Exception> _searchedLocation;
+
+        static ResourceManagerStringLocalizerLoggerExtensions()
+        {
+            _searchedLocation = LoggerMessage.Define<string, string, CultureInfo>(
+                LogLevel.Debug,
+                1,
+                $"{nameof(ResourceManagerStringLocalizer)} searched for '{{Key}}' in '{{LocationSearched}}' with culture '{{Culture}}'.");
+        }
+
+        public static void SearchedLocation(this ILogger logger, string key, string searchedLocation, CultureInfo culture)
+        {
+            _searchedLocation(logger, key, searchedLocation, culture, null);
+        }
+    }
+}

src/Microsoft.Extensions.Localization/Microsoft.Extensions.Localization.csproj

@@ -15,6 +15,7 @@
     <ProjectReference Include="..\Microsoft.Extensions.Localization.Abstractions\Microsoft.Extensions.Localization.Abstractions.csproj" />
     <PackageReference Include="Microsoft.Extensions.DependencyInjection.Abstractions" Version="1.2.0-*" />
     <PackageReference Include="Microsoft.Extensions.Options" Version="1.2.0-*" />
+    <PackageReference Include="Microsoft.Extensions.Logging.Abstractions" Version="1.2.0-*" />
   </ItemGroup>
 
   <ItemGroup Condition=" '$(TargetFramework)' == 'netstandard1.3' ">

src/Microsoft.Extensions.Localization/ResourceManagerStringLocalizer.cs

@@ -8,6 +8,7 @@
 using System.Reflection;
 using System.Resources;
 using Microsoft.Extensions.Localization.Internal;
+using Microsoft.Extensions.Logging;
 
 namespace Microsoft.Extensions.Localization
 {
@@ -23,6 +24,7 @@ public class ResourceManagerStringLocalizer : IStringLocalizer
         private readonly ResourceManager _resourceManager;
         private readonly IResourceStringProvider _resourceStringProvider;
         private readonly string _resourceBaseName;
+        private readonly ILogger _logger;
 
         /// <summary>
         /// Creates a new <see cref="ResourceManagerStringLocalizer"/>.
@@ -31,16 +33,19 @@ public class ResourceManagerStringLocalizer : IStringLocalizer
         /// <param name="resourceAssembly">The <see cref="Assembly"/> that contains the strings as embedded resources.</param>
         /// <param name="baseName">The base name of the embedded resource that contains the strings.</param>
         /// <param name="resourceNamesCache">Cache of the list of strings for a given resource assembly name.</param>
+        /// <param name="logger">The <see cref="ILogger"/>.</param>
         public ResourceManagerStringLocalizer(
             ResourceManager resourceManager,
             Assembly resourceAssembly,
             string baseName,
-            IResourceNamesCache resourceNamesCache)
+            IResourceNamesCache resourceNamesCache,
+            ILogger logger)
             : this(
                 resourceManager,
                 new AssemblyWrapper(resourceAssembly),
                 baseName,
-                resourceNamesCache)
+                resourceNamesCache,
+                logger)
         {
         }
 
@@ -51,12 +56,14 @@ public ResourceManagerStringLocalizer(
             ResourceManager resourceManager,
             AssemblyWrapper resourceAssemblyWrapper,
             string baseName,
-            IResourceNamesCache resourceNamesCache)
+            IResourceNamesCache resourceNamesCache,
+            ILogger logger)
             : this(
                   resourceManager,
                   new AssemblyResourceStringProvider(resourceNamesCache, resourceAssemblyWrapper, baseName),
                   baseName,
-                  resourceNamesCache)
+                  resourceNamesCache,
+                  logger)
         {
         }
 
@@ -67,7 +74,8 @@ public ResourceManagerStringLocalizer(
             ResourceManager resourceManager,
             IResourceStringProvider resourceStringProvider,
             string baseName,
-            IResourceNamesCache resourceNamesCache)
+            IResourceNamesCache resourceNamesCache,
+            ILogger logger)
         {
             if (resourceManager == null)
             {
@@ -89,10 +97,16 @@ public ResourceManagerStringLocalizer(
                 throw new ArgumentNullException(nameof(resourceNamesCache));
             }
 
+            if (logger == null)
+            {
+                throw new ArgumentNullException(nameof(logger));
+            }
+
             _resourceStringProvider = resourceStringProvider;
             _resourceManager = resourceManager;
             _resourceBaseName = baseName;
             _resourceNamesCache = resourceNamesCache;
+            _logger = logger;
         }
 
         /// <inheritdoc />
@@ -107,7 +121,7 @@ public virtual LocalizedString this[string name]
 
                 var value = GetStringSafely(name, null);
 
-                return new LocalizedString(name, value ?? name, resourceNotFound: value == null);
+                return new LocalizedString(name, value ?? name, resourceNotFound: value == null, searchedLocation: _resourceBaseName);
             }
         }
 
@@ -124,7 +138,7 @@ public virtual LocalizedString this[string name]
                 var format = GetStringSafely(name, null);
                 var value = string.Format(format ?? name, arguments);
 
-                return new LocalizedString(name, value, resourceNotFound: format == null);
+                return new LocalizedString(name, value, resourceNotFound: format == null, searchedLocation: _resourceBaseName);
             }
         }
 
@@ -140,13 +154,15 @@ public IStringLocalizer WithCulture(CultureInfo culture)
                     _resourceManager,
                     _resourceStringProvider,
                     _resourceBaseName,
-                    _resourceNamesCache)
+                    _resourceNamesCache,
+                    _logger)
                 : new ResourceManagerWithCultureStringLocalizer(
                     _resourceManager,
                     _resourceStringProvider,
                     _resourceBaseName,
                     _resourceNamesCache,
-                    culture);
+                    culture,
+                    _logger);
         }
 
         /// <inheritdoc />
@@ -173,7 +189,7 @@ protected IEnumerable<LocalizedString> GetAllStrings(bool includeParentCultures,
             foreach (var name in resourceNames)
             {
                 var value = GetStringSafely(name, culture);
-                yield return new LocalizedString(name, value ?? name, resourceNotFound: value == null);
+                yield return new LocalizedString(name, value ?? name, resourceNotFound: value == null, searchedLocation: _resourceBaseName);
             }
         }
 
@@ -191,7 +207,11 @@ protected string GetStringSafely(string name, CultureInfo culture)
                 throw new ArgumentNullException(nameof(name));
             }
 
-            var cacheKey = $"name={name}&culture={(culture ?? CultureInfo.CurrentUICulture).Name}";
+            var keyCulture = culture ?? CultureInfo.CurrentUICulture;
+
+            var cacheKey = $"name={name}&culture={keyCulture.Name}";
+
+            _logger.SearchedLocation(name, _resourceBaseName, keyCulture);
 
             if (_missingManifestCache.ContainsKey(cacheKey))
             {

src/Microsoft.Extensions.Localization/ResourceManagerStringLocalizerFactory.cs

@@ -6,6 +6,7 @@
 using System.IO;
 using System.Reflection;
 using System.Resources;
+using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Options;
 
 namespace Microsoft.Extensions.Localization
@@ -24,20 +25,30 @@ public class ResourceManagerStringLocalizerFactory : IStringLocalizerFactory
         private readonly ConcurrentDictionary<string, ResourceManagerStringLocalizer> _localizerCache =
             new ConcurrentDictionary<string, ResourceManagerStringLocalizer>();
         private readonly string _resourcesRelativePath;
+        private readonly ILoggerFactory _loggerFactory;
 
         /// <summary>
         /// Creates a new <see cref="ResourceManagerStringLocalizer"/>.
         /// </summary>
         /// <param name="localizationOptions">The <see cref="IOptions{LocalizationOptions}"/>.</param>
+        /// <param name="loggerFactory">The <see cref="ILoggerFactory"/>.</param>
         public ResourceManagerStringLocalizerFactory(
-            IOptions<LocalizationOptions> localizationOptions)
+            IOptions<LocalizationOptions> localizationOptions,
+            ILoggerFactory loggerFactory)
         {
             if (localizationOptions == null)
             {
                 throw new ArgumentNullException(nameof(localizationOptions));
             }
 
+            if (loggerFactory == null)
+            {
+                throw new ArgumentNullException(nameof(loggerFactory));
+            }
+
             _resourcesRelativePath = localizationOptions.Value.ResourcesPath ?? string.Empty;
+            _loggerFactory = loggerFactory;
+
             if (!string.IsNullOrEmpty(_resourcesRelativePath))
             {
                 _resourcesRelativePath = _resourcesRelativePath.Replace(Path.AltDirectorySeparatorChar, '.')
@@ -180,7 +191,8 @@ protected virtual ResourceManagerStringLocalizer CreateResourceManagerStringLoca
                 new ResourceManager(baseName, assembly),
                 assembly,
                 baseName,
-                _resourceNamesCache);
+                _resourceNamesCache,
+                _loggerFactory.CreateLogger<ResourceManagerStringLocalizer>());
         }
 
         /// <summary>

src/Microsoft.Extensions.Localization/ResourceManagerWithCultureStringLocalizer.cs

@@ -7,6 +7,7 @@
 using System.Reflection;
 using System.Resources;
 using Microsoft.Extensions.Localization.Internal;
+using Microsoft.Extensions.Logging;
 
 namespace Microsoft.Extensions.Localization
 {
@@ -26,13 +27,15 @@ public class ResourceManagerWithCultureStringLocalizer : ResourceManagerStringLo
         /// <param name="baseName">The base name of the embedded resource that contains the strings.</param>
         /// <param name="resourceNamesCache">Cache of the list of strings for a given resource assembly name.</param>
         /// <param name="culture">The specific <see cref="CultureInfo"/> to use.</param>
+        /// <param name="logger">The <see cref="ILogger"/>.</param>
         internal ResourceManagerWithCultureStringLocalizer(
             ResourceManager resourceManager,
             IResourceStringProvider resourceStringProvider,
             string baseName,
             IResourceNamesCache resourceNamesCache,
-            CultureInfo culture)
-            : base(resourceManager, resourceStringProvider, baseName, resourceNamesCache)
+            CultureInfo culture,
+            ILogger logger)
+            : base(resourceManager, resourceStringProvider, baseName, resourceNamesCache, logger)
         {
             if (resourceManager == null)
             {
@@ -70,13 +73,15 @@ internal ResourceManagerWithCultureStringLocalizer(
         /// <param name="baseName">The base name of the embedded resource that contains the strings.</param>
         /// <param name="resourceNamesCache">Cache of the list of strings for a given resource assembly name.</param>
         /// <param name="culture">The specific <see cref="CultureInfo"/> to use.</param>
+        /// <param name="logger">The <see cref="ILogger"/>.</param>
         public ResourceManagerWithCultureStringLocalizer(
             ResourceManager resourceManager,
             Assembly resourceAssembly,
             string baseName,
             IResourceNamesCache resourceNamesCache,
-            CultureInfo culture)
-            : base(resourceManager, resourceAssembly, baseName, resourceNamesCache)
+            CultureInfo culture,
+            ILogger logger)
+            : base(resourceManager, resourceAssembly, baseName, resourceNamesCache, logger)
         {
             if (resourceManager == null)
             {

test/Microsoft.AspNetCore.Localization.Tests/Microsoft.AspNetCore.Localization.Tests.csproj

@@ -10,6 +10,7 @@
   <ItemGroup>
     <ProjectReference Include="..\..\src\Microsoft.AspNetCore.Localization\Microsoft.AspNetCore.Localization.csproj" />
     <PackageReference Include="Microsoft.AspNetCore.TestHost" Version="1.2.0-*" />
+    <PackageReference Include="Microsoft.Extensions.Logging" Version="1.2.0-*" />
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="15.0.0-*" />
     <PackageReference Include="xunit" Version="2.2.0-*" />
     <PackageReference Include="xunit.runner.visualstudio" Version="2.2.0-*" />

test/Microsoft.Extensions.Localization.Tests/Microsoft.Extensions.Localization.Tests.csproj

@@ -9,7 +9,9 @@
 
   <ItemGroup>
     <ProjectReference Include="..\..\src\Microsoft.Extensions.Localization\Microsoft.Extensions.Localization.csproj" />
+    <PackageReference Include="Microsoft.AspNetCore.Testing" Version="1.2.0-*" />
     <PackageReference Include="Microsoft.Extensions.DependencyInjection" Version="1.2.0-*" />
+    <PackageReference Include="Microsoft.Extensions.Logging.Testing" Version="1.2.0-*" />
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="15.0.0-*" />
     <PackageReference Include="Moq" Version="4.6.36-*" />
     <PackageReference Include="xunit" Version="2.2.0-*" />