Merge branch '3.1.0GA_column-cache-concurency-fix' of git://github.com/grzpas/nhibernate-core into grzpas-3.1.0GA_column-cache-concurency-fix

Author: oskarb

src/NHibernate/AdoNet/ColumnNameCache.cs

@@ -1,10 +1,12 @@
 using System.Collections.Generic;
+using System.Threading;
 
 namespace NHibernate.AdoNet
 {
 	/// <summary> Implementation of ColumnNameCache. </summary>
 	public class ColumnNameCache
 	{
+        	private readonly ReaderWriterLockSlim cacheLock = new ReaderWriterLockSlim();
 		private readonly Dictionary<string, int?> columnNameToIndexCache;
 
 		public ColumnNameCache(int columnCount)
@@ -15,18 +17,45 @@ public ColumnNameCache(int columnCount)
 
 		public int GetIndexForColumnName(string columnName, ResultSetWrapper rs)
 		{
-			int? cached;
-			columnNameToIndexCache.TryGetValue(columnName, out cached);
+            		int? cached = Read(columnName);
 			if (cached.HasValue)
 			{
 				return cached.Value;
 			}
 			else
 			{
 				int index = rs.Target.GetOrdinal(columnName);
-				columnNameToIndexCache[columnName] = index;
+                		Insert(columnName, index);
 				return index;
 			}
 		}
+
+        	private int? Read(string key)
+	        {
+        	    cacheLock.EnterReadLock();
+	            try
+        	    {
+                	int? value;
+	                columnNameToIndexCache.TryGetValue(key, out value);
+        	        return value;
+	            }
+        	    finally
+	            {
+        	        cacheLock.ExitReadLock();
+	            }
+	        }
+
+	        private void Insert(string key, int value)
+        	{
+	            cacheLock.EnterWriteLock();
+        	    try
+	            {
+        	        columnNameToIndexCache[key] = value;
+	            }
+	            finally
+	            {
+	                cacheLock.ExitWriteLock();
+	            }
+	        }
 	}
 }