Imported Upstream version 4.6.0.125

Former-commit-id: a2155e9bd80020e49e72e86c44da02a8ac0e57a4

mcs/class/referencesource/System.Data/System/Data/Odbc/OdbcEnvironmentHandle.cs

@@ -0,0 +1,64 @@
+//------------------------------------------------------------------------------
+// <copyright file="OdbcEnvironmentHandle.cs" company="Microsoft">
+//      Copyright (c) Microsoft Corporation.  All rights reserved.
+// </copyright>
+// <owner current="true" primary="true">[....]</owner>
+// <owner current="true" primary="false">[....]</owner>
+//------------------------------------------------------------------------------
+
+using System;
+using System.Collections;
+using System.ComponentModel;
+using System.Data;
+using System.Data.Common;
+using System.Diagnostics;
+using System.Globalization;
+using System.Runtime.InteropServices;
+using System.Security;
+using System.Security.Permissions;
+using System.Text;
+using System.Threading;
+using System.Runtime.Versioning;
+
+namespace System.Data.Odbc {
+
+    sealed internal class OdbcEnvironmentHandle : OdbcHandle {
+
+        // SxS: this method uses SQLSetEnvAttr to setup ODBC environment handle settings. Environment handle is safe in SxS.
+        [ResourceExposure(ResourceScope.None)]
+        [ResourceConsumption(ResourceScope.Process, ResourceScope.Process)]
+        internal OdbcEnvironmentHandle() : base(ODBC32.SQL_HANDLE.ENV, null) {
+            ODBC32.RetCode retcode;
+            
+            //Set the expected driver manager version
+            //
+            retcode = UnsafeNativeMethods.SQLSetEnvAttr(
+                this,
+                ODBC32.SQL_ATTR.ODBC_VERSION,
+                ODBC32.SQL_OV_ODBC3,
+                ODBC32.SQL_IS.INTEGER);
+            // ignore retcode
+
+            //Turn on connection pooling
+            //Note: the env handle controls pooling.  Only those connections created under that
+            //handle are pooled.  So we have to keep it alive and not create a new environment
+            //for   every connection.
+            //
+            retcode = UnsafeNativeMethods.SQLSetEnvAttr(
+                this,
+                ODBC32.SQL_ATTR.CONNECTION_POOLING,
+                ODBC32.SQL_CP_ONE_PER_HENV,
+                ODBC32.SQL_IS.INTEGER);
+
+            switch(retcode) {
+            case ODBC32.RetCode.SUCCESS:
+            case ODBC32.RetCode.SUCCESS_WITH_INFO:
+                break;
+            default:
+                Dispose();
+                throw ODBC.CantEnableConnectionpooling(retcode);
+            }
+        }
+    }
+}
+