Imported Upstream version 4.0.0~alpha1

Former-commit-id: 806294f5ded97629b74c85c09952f2a74fe182d9

mcs/class/System.Runtime.Caching/ReferenceSources/SRef.cs

@@ -0,0 +1,28 @@
+using System;
+using System.Runtime.InteropServices;
+
+namespace System.Runtime.Caching {
+    /*
+     * This class is used to retrieve the size of an object graph.
+     * Although Mono has not a way of computing this.
+     * Known problems:
+     *   - CacheMemoryMonitor does not trim the cache when it reaches its memory size limit.
+     *   - IMemoryCacheManager.UpdateCacheSize is called with incorrect size.
+     */
+    internal class SRef {
+
+        private Object _sizedRef;
+
+        internal SRef (Object target) {
+            _sizedRef = target;
+        }
+
+        internal long ApproximateSize {
+            get { return (long) Marshal.SizeOf (_sizedRef.GetType ()); }
+        }
+
+        internal void Dispose() {
+
+        }
+    }
+}