Imported Upstream version 4.6.0.125

Former-commit-id: a2155e9bd80020e49e72e86c44da02a8ac0e57a4

mcs/class/referencesource/System.Data.Entity/System/Data/Common/QueryCache/QueryCacheKey.cs

@@ -0,0 +1,122 @@
+//------------------------------------------------------------------------------
+// <copyright file="QueryCacheKey.cs" company="Microsoft">
+//      Copyright (c) Microsoft Corporation.  All rights reserved.
+// </copyright>
+//
+// @owner  [....]
+// @backupOwner [....]
+//------------------------------------------------------------------------------
+
+namespace System.Data.Common.QueryCache
+{
+    using System;
+    using System.Collections.Generic;
+    using System.Text;
+
+
+    /// <summary>
+    /// represents an abstract cache key
+    /// </summary>
+    internal abstract class QueryCacheKey
+    {
+        #region Constants
+        protected const int EstimatedParameterStringSize = 20;
+        #endregion
+
+        #region Fields
+        /// <summary>
+        /// entry hit counter
+        /// </summary>
+        private uint _hitCount;
+
+        /// <summary>
+        /// aging index
+        /// </summary>
+        private int _agingIndex;
+
+        /// <summary>
+        /// default string comparison kind - Ordinal
+        /// </summary>
+        protected static StringComparison _stringComparison = StringComparison.Ordinal;
+        #endregion
+
+        #region Constructor
+        protected QueryCacheKey()
+        {
+            _hitCount = 1;
+        }
+        #endregion
+
+        #region Abstract Methods
+        /// <summary>
+        /// Determines whether two instances of QueryCacheContext are equal. 
+        /// Equality is value based.
+        /// </summary>
+        /// <param name="obj"></param>
+        /// <returns></returns>
+        public abstract override bool Equals( object obj );
+
+        /// <summary>
+        /// Returns QueryCacheContext instance HashCode
+        /// </summary>
+        /// <returns></returns>
+        public abstract override int GetHashCode();
+        #endregion
+
+        #region Internal API
+        /// <summary>
+        /// Cache entry hit count
+        /// </summary>
+        internal uint HitCount
+        {
+            get 
+            { 
+                return _hitCount; 
+            }
+            
+            set 
+            { 
+                _hitCount = value; 
+            }
+        }
+
+        /// <summary>
+        /// Gets/Sets Aging index for cache entry
+        /// </summary>
+        internal int AgingIndex
+        {
+            get 
+            { 
+                return _agingIndex; 
+            }
+            
+            set 
+            { 
+                _agingIndex = value; 
+            }
+        }
+
+        /// <summary>
+        /// Updates hit count
+        /// </summary>
+        internal void UpdateHit()
+        {
+            if (uint.MaxValue != _hitCount)
+            {
+                unchecked { _hitCount++; }
+            }
+        }
+
+        /// <summary>
+        /// default string comparer
+        /// </summary>
+        /// <param name="s"></param>
+        /// <param name="t"></param>
+        /// <returns></returns>
+        protected virtual bool Equals( string s, string t )
+        {
+            return String.Equals(s, t, _stringComparison);
+        }
+        #endregion
+    }
+}