Add EvictionMetadata

src/Microsoft.Extensions.Caching.Abstractions/CacheEntryExtensions.cs

@@ -136,6 +136,7 @@ public static ICacheEntry SetOptions(this ICacheEntry entry, MemoryCacheEntryOpt
             entry.AbsoluteExpiration = options.AbsoluteExpiration;
             entry.AbsoluteExpirationRelativeToNow = options.AbsoluteExpirationRelativeToNow;
             entry.SlidingExpiration = options.SlidingExpiration;
+            entry.EvictionMetadata = options.EvictionMetadata;
 
             foreach (var expirationToken in options.ExpirationTokens)
             {

src/Microsoft.Extensions.Caching.Abstractions/ICacheEntry.cs

@@ -38,6 +38,8 @@ public interface ICacheEntry : IDisposable
         /// </summary>
         TimeSpan? SlidingExpiration { get; set; }
 
+        object EvictionMetadata { get; set; }
+
         /// <summary>
         /// Gets the <see cref="IChangeToken"/> instances which cause the cache entry to expire.
         /// </summary>
@@ -47,6 +49,5 @@ public interface ICacheEntry : IDisposable
         /// Gets or sets the callbacks will be fired after the cache entry is evicted from the cache.
         /// </summary>
         IList<PostEvictionCallbackRegistration> PostEvictionCallbacks { get; }
-
     }
 }

src/Microsoft.Extensions.Caching.Abstractions/MemoryCacheEntryExtensions.cs

@@ -66,6 +66,14 @@ public static MemoryCacheEntryOptions SetSlidingExpiration(
             return options;
         }
 
+        public static MemoryCacheEntryOptions SetEvictionMetadata(
+            this MemoryCacheEntryOptions options,
+            object metadata)
+        {
+            options.EvictionMetadata = metadata;
+            return options;
+        }
+
         /// <summary>
         /// The given callback will be fired after the cache entry is evicted from the cache.
         /// </summary>

src/Microsoft.Extensions.Caching.Abstractions/MemoryCacheEntryOptions.cs

@@ -74,6 +74,8 @@ public TimeSpan? SlidingExpiration
             }
         }
 
+        public object EvictionMetadata { get; set; }
+
         /// <summary>
         /// Gets the <see cref="IChangeToken"/> instances which cause the cache entry to expire.
         /// </summary>

src/Microsoft.Extensions.Caching.Memory/CacheEntry.cs

@@ -9,7 +9,7 @@
 
 namespace Microsoft.Extensions.Caching.Memory
 {
-    public class CacheEntry : ICacheEntry, IRetrievedCacheEntry
+    internal class CacheEntry : ICacheEntry, IRetrievedCacheEntry
     {
         private bool _added = false;
         private static readonly Action<object> ExpirationCallback = ExpirationTokensExpired;
@@ -157,6 +157,8 @@ public IList<PostEvictionCallbackRegistration> PostEvictionCallbacks
 
         internal EvictionReason EvictionReason { get; private set; }
 
+        public object EvictionMetadata { get; set; }
+
         public void Dispose()
         {
             if (!_added)

src/Microsoft.Extensions.Caching.Memory/Interfaces/IRetrievedCacheEntry.cs

@@ -31,6 +31,8 @@ public interface IRetrievedCacheEntry
         /// </summary>
         TimeSpan? SlidingExpiration { get; }
 
+        object EvictionMetadata { get; }
+
         DateTimeOffset LastAccessed { get; }
 
         bool IsExpired { get; }

src/Microsoft.Extensions.Caching.Memory/MemoryCache.cs

@@ -2,6 +2,7 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
+using System.Collections;
 using System.Collections.Concurrent;
 using System.Collections.Generic;
 using System.Linq;
@@ -249,7 +250,7 @@ private bool ExecuteCacheEviction()
         {
             var evictedEntries = false;
             var utcNow = _clock.UtcNow;
-            var freshEntries = new List<CacheEntry>();
+            var freshEntries = new List<IRetrievedCacheEntry>();
 
             // TODO: evaluate the perf overhead of enumerators vs taking a snapshot
             foreach (var entry in _entries)