1 files changed, 57 insertions, 0 deletions
diff --git a/src/mscorlib/src/System/Threading/LockCookie.cs b/src/mscorlib/src/System/Threading/LockCookie.cs
new file mode 100644
index 0000000000..c1fbfd828e
--- /dev/null
+++ b/src/mscorlib/src/System/Threading/LockCookie.cs
@@ -0,0 +1,57 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+//
+/*============================================================
+**
+**
+**
+** Purpose: Defines the lock that implements 
+**          single-writer/multiple-reader semantics
+**
+**
+===========================================================*/
+
+namespace System.Threading {
+
+    using System;
+    [System.Runtime.InteropServices.ComVisible(true)]
+    public struct LockCookie
+    {
+        private int _dwFlags;
+        private int _dwWriterSeqNum;
+        private int _wReaderAndWriterLevel;
+        private int _dwThreadID;
+
+        public override int GetHashCode()
+        {
+            return _dwFlags + _dwWriterSeqNum + _wReaderAndWriterLevel + _dwThreadID;
+        }
+        
+        public override bool Equals(Object obj)
+        {
+            if (obj is LockCookie)
+                return Equals((LockCookie)obj);
+            else
+                return false;
+        }
+        
+        public bool Equals(LockCookie obj)
+        {
+            return obj._dwFlags == _dwFlags && obj._dwWriterSeqNum == _dwWriterSeqNum &&
+                obj._wReaderAndWriterLevel == _wReaderAndWriterLevel && obj._dwThreadID == _dwThreadID;
+        }
+        
+        public static bool operator ==(LockCookie a, LockCookie b)
+        {
+            return a.Equals(b);
+        }
+        
+        public static bool operator !=(LockCookie a, LockCookie b)
+        {
+            return !(a == b);
+        }
+    }
+}
+