From d7064e8837e4545f95fb831cb33448d87acd1162 Mon Sep 17 00:00:00 2001
From: Badrish Chandramouli <badrishc@microsoft.com>
Date: Tue, 13 Aug 2019 15:51:22 -0700
Subject: [PATCH] Updated fast threadlocal

---
 cs/src/core/Epochs/FastThreadLocal.cs | 30 ++++++++++++++++-----------
 1 file changed, 18 insertions(+), 12 deletions(-)

diff --git a/cs/src/core/Epochs/FastThreadLocal.cs b/cs/src/core/Epochs/FastThreadLocal.cs
index e9f53656f..cfd93ca4b 100644
--- a/cs/src/core/Epochs/FastThreadLocal.cs
+++ b/cs/src/core/Epochs/FastThreadLocal.cs
@@ -2,6 +2,7 @@
 // Licensed under the MIT license.
 
 using System;
+using System.Net;
 using System.Threading;
 
 namespace FASTER.core
@@ -17,15 +18,22 @@ internal class FastThreadLocal<T>
 
         [ThreadStatic]
         private static T[] values;
+        [ThreadStatic]
+        private static int t_iid;
 
         private readonly int id;
+        private readonly int iid;
+
         private static readonly int[] instances = new int[kMaxInstances];
+        private static int instanceId = 0;
 
         public FastThreadLocal()
         {
+            iid = Interlocked.Increment(ref instanceId);
+
             for (int i = 0; i < kMaxInstances; i++)
             {
-                if (0 == Interlocked.CompareExchange(ref instances[i], 1, 0))
+                if (0 == Interlocked.CompareExchange(ref instances[i], iid, 0))
                 {
                     id = i;
                     return;
@@ -37,21 +45,19 @@ public FastThreadLocal()
         public void InitializeThread()
         {
             if (values == null)
+            {
                 values = new T[kMaxInstances];
+            }
+            if (t_iid != iid)
+            {
+                t_iid = iid;
+                values[id] = default(T);
+            }
         }
 
         public void DisposeThread()
         {
-            Value = default(T);
-
-            // Dispose values only if there are no other
-            // instances active for this thread
-            for (int i = 0; i < kMaxInstances; i++)
-            {
-                if ((instances[i] == 1) && (i != id))
-                    return;
-            }
-            values = null;
+            values[id] = default(T);
         }
 
         /// <summary>
@@ -68,6 +74,6 @@ public T Value
             set => values[id] = value;
         }
 
-        public bool IsInitializedForThread => values != null;
+        public bool IsInitializedForThread => (values != null) && (iid == t_iid);
     }
 }