From 4a069107fa589ceef8dc2926651dbb053f625bf7 Mon Sep 17 00:00:00 2001
From: Alex Peck <alexpeck@microsoft.com>
Date: Thu, 16 Dec 2021 13:31:46 -0800
Subject: [PATCH 1/2] keys

---
 BitFaster.Caching.UnitTests/Lru/ConcurrentLruTests.cs | 9 +++++++++
 BitFaster.Caching/Lru/TemplateConcurrentLru.cs        | 5 +++++
 2 files changed, 14 insertions(+)

diff --git a/BitFaster.Caching.UnitTests/Lru/ConcurrentLruTests.cs b/BitFaster.Caching.UnitTests/Lru/ConcurrentLruTests.cs
index e84008f1..76370822 100644
--- a/BitFaster.Caching.UnitTests/Lru/ConcurrentLruTests.cs
+++ b/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()
         {
diff --git a/BitFaster.Caching/Lru/TemplateConcurrentLru.cs b/BitFaster.Caching/Lru/TemplateConcurrentLru.cs
index e5043d4b..691a0e3b 100644
--- a/BitFaster.Caching/Lru/TemplateConcurrentLru.cs
+++ b/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)
         {

From 86c0c010ba293b058e35b4e075d9d121a046bb6f Mon Sep 17 00:00:00 2001
From: Alex Peck <alexpeck@microsoft.com>
Date: Thu, 16 Dec 2021 13:42:07 -0800
Subject: [PATCH 2/2] classic

---
 BitFaster.Caching.UnitTests/Lru/ClassicLruTests.cs | 9 +++++++++
 BitFaster.Caching/Lru/ClassicLru.cs                | 8 ++++++++
 2 files changed, 17 insertions(+)

diff --git a/BitFaster.Caching.UnitTests/Lru/ClassicLruTests.cs b/BitFaster.Caching.UnitTests/Lru/ClassicLruTests.cs
index a6b8c825..435414ff 100644
--- a/BitFaster.Caching.UnitTests/Lru/ClassicLruTests.cs
+++ b/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()
         {
diff --git a/BitFaster.Caching/Lru/ClassicLru.cs b/BitFaster.Caching/Lru/ClassicLru.cs
index c0f19156..ba14116f 100644
--- a/BitFaster.Caching/Lru/ClassicLru.cs
+++ b/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)
         {