Adjusts IVarantManager to use ValueTask (#293)

Author: rossgrambo

src/Microsoft.FeatureManagement/FeatureManager.cs

@@ -71,25 +71,25 @@ public FeatureManager(
 
         public Task<bool> IsEnabledAsync(string feature)
         {
-            return IsEnabledWithVariantsAsync<object>(feature, appContext: null, useAppContext: false, CancellationToken.None);
+            return IsEnabledWithVariantsAsync<object>(feature, appContext: null, useAppContext: false, CancellationToken.None).AsTask();
         }
 
         public Task<bool> IsEnabledAsync<TContext>(string feature, TContext appContext)
         {
-            return IsEnabledWithVariantsAsync(feature, appContext, useAppContext: true, CancellationToken.None);
+            return IsEnabledWithVariantsAsync(feature, appContext, useAppContext: true, CancellationToken.None).AsTask();
         }
 
-        public Task<bool> IsEnabledAsync(string feature, CancellationToken cancellationToken)
+        public ValueTask<bool> IsEnabledAsync(string feature, CancellationToken cancellationToken)
         {
             return IsEnabledWithVariantsAsync<object>(feature, appContext: null, useAppContext: false, cancellationToken);
         }
 
-        public Task<bool> IsEnabledAsync<TContext>(string feature, TContext appContext, CancellationToken cancellationToken)
+        public ValueTask<bool> IsEnabledAsync<TContext>(string feature, TContext appContext, CancellationToken cancellationToken)
         {
             return IsEnabledWithVariantsAsync(feature, appContext, useAppContext: true, cancellationToken);
         }
 
-        private async Task<bool> IsEnabledWithVariantsAsync<TContext>(string feature, TContext appContext, bool useAppContext, CancellationToken cancellationToken)
+        private async ValueTask<bool> IsEnabledWithVariantsAsync<TContext>(string feature, TContext appContext, bool useAppContext, CancellationToken cancellationToken)
         {
             bool isFeatureEnabled = false;
 

src/Microsoft.FeatureManagement/FeatureManagerSnapshot.cs

@@ -17,7 +17,7 @@ namespace Microsoft.FeatureManagement
     class FeatureManagerSnapshot : IFeatureManagerSnapshot, IVariantFeatureManagerSnapshot
     {
         private readonly IVariantFeatureManager _featureManager;
-        private readonly ConcurrentDictionary<string, Task<bool>> _flagCache = new ConcurrentDictionary<string, Task<bool>>();
+        private readonly ConcurrentDictionary<string, ValueTask<bool>> _flagCache = new ConcurrentDictionary<string, ValueTask<bool>>();
         private readonly ConcurrentDictionary<string, Variant> _variantCache = new ConcurrentDictionary<string, Variant>();
         private IEnumerable<string> _featureNames;
 
@@ -55,24 +55,24 @@ public Task<bool> IsEnabledAsync(string feature)
         {
             return _flagCache.GetOrAdd(
                 feature,
-                (key) => _featureManager.IsEnabledAsync(key, CancellationToken.None));
+                (key) => _featureManager.IsEnabledAsync(key, CancellationToken.None)).AsTask();
         }
 
         public Task<bool> IsEnabledAsync<TContext>(string feature, TContext context)
         {
             return _flagCache.GetOrAdd(
                 feature,
-                (key) => _featureManager.IsEnabledAsync(key, context, CancellationToken.None));
+                (key) => _featureManager.IsEnabledAsync(key, context, CancellationToken.None)).AsTask();
         }
 
-        public Task<bool> IsEnabledAsync(string feature, CancellationToken cancellationToken)
+        public ValueTask<bool> IsEnabledAsync(string feature, CancellationToken cancellationToken)
         {
             return _flagCache.GetOrAdd(
                 feature,
                 (key) => _featureManager.IsEnabledAsync(key, cancellationToken));
         }
 
-        public Task<bool> IsEnabledAsync<TContext>(string feature, TContext context, CancellationToken cancellationToken)
+        public ValueTask<bool> IsEnabledAsync<TContext>(string feature, TContext context, CancellationToken cancellationToken)
         {
             return _flagCache.GetOrAdd(
                 feature,

src/Microsoft.FeatureManagement/IVariantFeatureManager.cs

@@ -25,7 +25,7 @@ public interface IVariantFeatureManager
         /// <param name="feature">The name of the feature to check.</param>
         /// <param name="cancellationToken">The cancellation token to cancel the operation.</param>
         /// <returns>True if the feature is enabled, otherwise false.</returns>
-        Task<bool> IsEnabledAsync(string feature, CancellationToken cancellationToken);
+        ValueTask<bool> IsEnabledAsync(string feature, CancellationToken cancellationToken);
 
         /// <summary>
         /// Checks whether a given feature is enabled.
@@ -34,7 +34,7 @@ public interface IVariantFeatureManager
         /// <param name="context">A context providing information that can be used to evaluate whether a feature should be on or off.</param>
         /// <param name="cancellationToken">The cancellation token to cancel the operation.</param>
         /// <returns>True if the feature is enabled, otherwise false.</returns>
-        Task<bool> IsEnabledAsync<TContext>(string feature, TContext context, CancellationToken cancellationToken);
+        ValueTask<bool> IsEnabledAsync<TContext>(string feature, TContext context, CancellationToken cancellationToken);
 
         /// <summary>
         /// Gets the assigned variant for a specific feature.