Imported Upstream version 4.6.0.125

Former-commit-id: a2155e9bd80020e49e72e86c44da02a8ac0e57a4

mcs/class/referencesource/System.ServiceModel/System/ServiceModel/Transactions/TransactionCache.cs

@@ -0,0 +1,145 @@
+//------------------------------------------------------------
+// Copyright (c) Microsoft Corporation.  All rights reserved.
+//------------------------------------------------------------
+namespace System.ServiceModel.Transactions
+{
+    using System;
+    using System.Collections.Generic;
+    using System.Diagnostics;
+    using System.ServiceModel;
+    using System.ServiceModel.Channels;
+    using System.ServiceModel.Security;
+    using System.Threading;
+    using System.Transactions;
+    using System.Xml;
+
+    //------------------------------------------------------------------------------------------
+    //                          Transaction caches
+    //------------------------------------------------------------------------------------------
+    class WsatExtendedInformationCache : TransactionCache<Transaction, WsatExtendedInformation>
+    {
+        public static void Cache(Transaction tx, WsatExtendedInformation info)
+        {
+            WsatExtendedInformationCache entry = new WsatExtendedInformationCache();
+            entry.AddEntry(tx, tx, info);
+        }
+    }
+
+    class WsatIncomingTransactionCache : TransactionCache<string, Transaction>
+    {
+        public static void Cache(string identifier, Transaction tx)
+        {
+            WsatIncomingTransactionCache entry = new WsatIncomingTransactionCache();
+            entry.AddEntry(tx, identifier, tx);
+        }
+    }
+    
+    abstract class TransactionCache<T, S>
+    {
+        static Dictionary<T, S> cache = new Dictionary<T, S>();
+        static ReaderWriterLock cacheLock = new ReaderWriterLock();
+
+        T key;
+
+        protected void AddEntry(Transaction transaction, T key, S value)
+        {
+            this.key = key;
+
+            if (Add(key, value))
+            {
+                transaction.TransactionCompleted += new TransactionCompletedEventHandler(OnTransactionCompleted);
+            }
+        }
+
+        void OnTransactionCompleted(object sender, TransactionEventArgs e)
+        {
+            Remove(this.key);
+        }
+
+        static bool Add(T key, S value)
+        {
+            bool lockHeld = false;
+            try
+            {
+                try { }
+                finally
+                {
+                    cacheLock.AcquireWriterLock(Timeout.Infinite);
+                    lockHeld = true;
+                }
+
+                if (!cache.ContainsKey(key))
+                {
+                    cache.Add(key, value);
+                    return true;
+                }
+            }
+            finally
+            {
+                if (lockHeld)
+                {
+                    cacheLock.ReleaseWriterLock();
+                }
+            }
+
+            return false;
+        }
+
+        static void Remove(T key)
+        {
+            bool lockHeld = false;
+            try
+            {
+                try { }
+                finally
+                {
+                    cacheLock.AcquireWriterLock(Timeout.Infinite);
+                    lockHeld = true;
+                }
+
+                bool remove = cache.Remove(key);
+                if (!(remove))
+                {
+                    // tx processing requires failfast when state is inconsistent
+                    DiagnosticUtility.FailFast("TransactionCache: key must be present in transaction cache");
+                }
+            }
+            finally
+            {
+                if (lockHeld)
+                {
+                    cacheLock.ReleaseWriterLock();
+                }
+            }
+
+        }
+
+        public static bool Find(T key, out S value)
+        {
+            bool lockHeld = false;
+            try
+            {
+                try { }
+                finally
+                {
+                    cacheLock.AcquireReaderLock(Timeout.Infinite);
+                    lockHeld = true;
+                }
+
+                if (cache.TryGetValue(key, out value))
+                {
+                    return true;
+                }
+            }
+            finally
+            {
+                if (lockHeld)
+                {
+                    cacheLock.ReleaseReaderLock();
+                }
+            }
+
+            return false;
+        }
+    }
+}