enumerate keys

BitFaster.Caching.UnitTests/Lru/ClassicLruTests.cs

@@ -56,6 +56,15 @@ public void WhenItemIsAddedCountIsCorrect()
             lru.Count.Should().Be(1);
         }
 
+        [Fact]
+        public void WhenItemsAddedKeysContainsTheKeys()
+        {
+            lru.Count.Should().Be(0);
+            lru.GetOrAdd(1, valueFactory.Create);
+            lru.GetOrAdd(2, valueFactory.Create);
+            lru.Keys.Should().BeEquivalentTo(new[] { 1, 2 });
+        }
+
         [Fact]
         public void WhenItemExistsTryGetReturnsValueAndTrue()
         {

BitFaster.Caching.UnitTests/Lru/ConcurrentLruTests.cs

@@ -108,6 +108,15 @@ public async Task WhenItemIsAddedCountIsCorrectAsync()
             lru.Count.Should().Be(1);
         }
 
+        [Fact]
+        public void WhenItemsAddedKeysContainsTheKeys()
+        {
+            lru.Count.Should().Be(0);
+            lru.GetOrAdd(1, valueFactory.Create);
+            lru.GetOrAdd(2, valueFactory.Create);
+            lru.Keys.Should().BeEquivalentTo(new[] { 1, 2 });
+        }
+
         [Fact]
         public void WhenItemExistsTryGetReturnsValueAndTrue()
         {

BitFaster.Caching/Lru/ClassicLru.cs

@@ -49,8 +49,16 @@ public ClassicLru(int concurrencyLevel, int capacity, IEqualityComparer<K> compa
 
         public int Count => this.linkedList.Count;
 
+        /// <summary>
+        /// Gets the ratio of hits to misses, where a value of 1 indicates 100% hits.
+        /// </summary>
         public double HitRatio => (double)requestHitCount / (double)requestTotalCount;
 
+        /// <summary>
+        /// Gets a collection containing the keys in the cache.
+        /// </summary>
+        public ICollection<K> Keys => this.dictionary.Keys;
+
         ///<inheritdoc/>
         public bool TryGet(K key, out V value)
         {

BitFaster.Caching/Lru/TemplateConcurrentLru.cs

@@ -96,6 +96,11 @@ public TemplateConcurrentLru(
 
         public int ColdCount => this.coldCount;
 
+        /// <summary>
+        /// Gets a collection containing the keys in the cache.
+        /// </summary>
+        public ICollection<K> Keys => this.dictionary.Keys;
+
         ///<inheritdoc/>
         public bool TryGet(K key, out V value)
         {