add implementation

dotnet · Aug 18, 2021 · 378bfbe · 378bfbe
1 parent 40df3a3
commit 378bfbe
Showing 1 changed file with 16 additions and 4 deletions.
diff --git a/src/libraries/Microsoft.Extensions.Caching.Memory/src/MemoryCache.cs b/src/libraries/Microsoft.Extensions.Caching.Memory/src/MemoryCache.cs
@@ -23,8 +23,8 @@ public class MemoryCache : IMemoryCache
         internal readonly ILogger _logger;
 
         private readonly MemoryCacheOptions _options;
-        private readonly ConcurrentDictionary<object, CacheEntry> _entries;
 
+        private ConcurrentDictionary<object, CacheEntry> _entries;
         private long _cacheSize;
         private bool _disposed;
         private DateTimeOffset _lastExpirationScan;
@@ -260,8 +260,8 @@ public bool TryGetValue(object key, out object result)
         public void Remove(object key)
         {
             ValidateCacheKey(key);
-
             CheckDisposed();
+
             if (_entries.TryRemove(key, out CacheEntry entry))
             {
                 if (_options.SizeLimit.HasValue)
@@ -281,7 +281,17 @@ public void Remove(object key)
         /// </summary>
         public void Clear()
         {
+            CheckDisposed();
 
+            var oldEntries = Interlocked.Exchange(ref _entries, new ConcurrentDictionary<object, CacheEntry>());
+            Interlocked.Exchange(ref _cacheSize, 0);
+
+            foreach (var entry in oldEntries)
+            {
+                entry.Value.SetExpired(EvictionReason.Removed);
+                entry.Value.InvokeEvictionCallbacks();
+            }
+            oldEntries.Clear();
         }
 
         private void RemoveEntry(CacheEntry entry)
@@ -325,7 +335,8 @@ private static void ScanForExpiredItems(MemoryCache cache)
         {
             DateTimeOffset now = cache._lastExpirationScan = cache._options.Clock.UtcNow;
 
-            foreach (KeyValuePair<object, CacheEntry> item in cache._entries)
+            var entries = cache._entries; // Clear() can update the reference in the meantime
+            foreach (KeyValuePair<object, CacheEntry> item in entries)
             {
                 CacheEntry entry = item.Value;
 
@@ -410,7 +421,8 @@ private void Compact(long removalSizeTarget, Func<CacheEntry, long> computeEntry
 
             // Sort items by expired & priority status
             DateTimeOffset now = _options.Clock.UtcNow;
-            foreach (KeyValuePair<object, CacheEntry> item in _entries)
+            var entries = _entries; // Clear() can update the reference in the meantime
+            foreach (KeyValuePair<object, CacheEntry> item in entries)
             {
                 CacheEntry entry = item.Value;
                 if (entry.CheckExpired(now))