Integrate main commits into feature/v3 branch.

src/Microsoft.FeatureManagement.AspNetCore/Microsoft.FeatureManagement.AspNetCore.csproj

@@ -4,7 +4,7 @@
   <!-- Official Version -->
   <PropertyGroup>
     <MajorVersion>2</MajorVersion>
-    <MinorVersion>3</MinorVersion>
+    <MinorVersion>4</MinorVersion>
     <PatchVersion>0</PatchVersion>
   </PropertyGroup>
 

src/Microsoft.FeatureManagement/FeatureFilters/PercentageFilter.cs

@@ -48,7 +48,7 @@ public Task<bool> EvaluateAsync(FeatureFilterEvaluationContext context, Cancella
 
             if (result)
             {
-                result = (RandomGenerator.NextDouble() * 100) <= settings.Value;
+                result = (RandomGenerator.NextDouble() * 100) < settings.Value;
             }
 
             return Task.FromResult(result);

src/Microsoft.FeatureManagement/FeatureManagementError.cs

@@ -18,6 +18,11 @@ public enum FeatureManagementError
         /// </summary>
         AmbiguousFeatureFilter,
 
+        /// <summary>
+        /// A feature that was requested for evaluation was not found.
+        /// </summary>
+        MissingFeature,
+
         /// <summary>
         /// A feature filter being used in feature evaluation is invalid.
         /// </summary>
@@ -43,11 +48,6 @@ public enum FeatureManagementError
         /// </summary>
         InvalidFeatureVariantAssigner,
 
-        /// <summary>
-        /// A feature that was requested for evaluation was not found.
-        /// </summary>
-        MissingFeature,
-
         /// <summary>
         /// A dynamic feature does not have any feature variants registered.
         /// </summary>

src/Microsoft.FeatureManagement/FeatureManagementOptions.cs

@@ -11,7 +11,15 @@ public class FeatureManagementOptions
         /// <summary>
         /// Controls the behavior of feature evaluation when dependent feature filters are missing.
         /// If missing feature filters are not ignored an exception will be thrown when attempting to evaluate a feature that depends on a missing feature filter.
+        /// The default value is false.
         /// </summary>
         public bool IgnoreMissingFeatureFilters { get; set; }
+
+        /// <summary>
+        /// Controls the behavior of feature evaluation when the target feature is missing.
+        /// If missing features are not ignored an exception will be thrown when attempting to evaluate them.
+        /// The default value is true.
+        /// </summary>
+        public bool IgnoreMissingFeatures { get; set; } = true;
     }
 }

src/Microsoft.FeatureManagement/FeatureManager.cs

@@ -161,6 +161,19 @@ private async Task<bool> IsEnabledAsync<TContext>(string feature, TContext appCo
                     }
                 }
             }
+            else
+            {
+                string errorMessage = $"The feature declaration for the feature '{feature}' was not found.";
+
+                if (!_options.IgnoreMissingFeatures)
+                {
+                    throw new FeatureManagementException(FeatureManagementError.MissingFeature, errorMessage);
+                }
+                else
+                {
+                    _logger.LogWarning(errorMessage);
+                }
+            }
 
             foreach (ISessionManager sessionManager in _sessionManagers)
             {

src/Microsoft.FeatureManagement/FeatureManagerSnapshot.cs

@@ -2,6 +2,7 @@
 // Licensed under the MIT license.
 //
 using System;
+using System.Collections.Concurrent;
 using System.Collections.Generic;
 using System.Runtime.CompilerServices;
 using System.Threading;
@@ -15,7 +16,7 @@ namespace Microsoft.FeatureManagement
     class FeatureManagerSnapshot : IFeatureManagerSnapshot
     {
         private readonly IFeatureManager _featureManager;
-        private readonly IDictionary<string, bool> _flagCache = new Dictionary<string, bool>();
+        private readonly ConcurrentDictionary<string, Task<bool>> _flagCache = new ConcurrentDictionary<string, Task<bool>>();
         private IEnumerable<string> _featureFlagNames;
 
         public FeatureManagerSnapshot(IFeatureManager featureManager)
@@ -43,36 +44,18 @@ public async IAsyncEnumerable<string> GetFeatureFlagNamesAsync([EnumeratorCancel
             }
         }
 
-        public async Task<bool> IsEnabledAsync(string feature, CancellationToken cancellationToken)
+        public Task<bool> IsEnabledAsync(string feature, CancellationToken cancellationToken)
         {
-            //
-            // First, check local cache
-            if (_flagCache.ContainsKey(feature))
-            {
-                return _flagCache[feature];
-            }
-
-            bool enabled = await _featureManager.IsEnabledAsync(feature, cancellationToken).ConfigureAwait(false);
-
-            _flagCache[feature] = enabled;
-
-            return enabled;
+            return _flagCache.GetOrAdd(
+                feature,
+                (key) => _featureManager.IsEnabledAsync(key, cancellationToken));
         }
 
-        public async Task<bool> IsEnabledAsync<TContext>(string feature, TContext context, CancellationToken cancellationToken)
+        public Task<bool> IsEnabledAsync<TContext>(string feature, TContext context, CancellationToken cancellationToken)
         {
-            //
-            // First, check local cache
-            if (_flagCache.ContainsKey(feature))
-            {
-                return _flagCache[feature];
-            }
-
-            bool enabled = await _featureManager.IsEnabledAsync(feature, context, cancellationToken).ConfigureAwait(false);
-
-            _flagCache[feature] = enabled;
-
-            return enabled;
+            return _flagCache.GetOrAdd(
+                feature,
+                (key) => _featureManager.IsEnabledAsync(key, context, cancellationToken));
         }
     }
 }

src/Microsoft.FeatureManagement/FilterAliasAttribute.cs

@@ -18,7 +18,7 @@ public FilterAliasAttribute(string alias)
         {
             if (string.IsNullOrEmpty(alias))
             {
-                throw new ArgumentNullException(alias);
+                throw new ArgumentNullException(nameof(alias));
             }
 
             Alias = alias;

src/Microsoft.FeatureManagement/Microsoft.FeatureManagement.csproj

@@ -3,10 +3,9 @@
 
   <!-- Official Version -->
   <PropertyGroup>
-    <MajorVersion>3</MajorVersion>
-    <MinorVersion>0</MinorVersion>
+    <MajorVersion>2</MajorVersion>
+    <MinorVersion>4</MinorVersion>
     <PatchVersion>0</PatchVersion>
-    <PreviewVersion>-preview</PreviewVersion>
   </PropertyGroup>
 
   <Import Project="..\..\build\Versioning.props" />