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

   1 //------------------------------------------------------------------------------
   2 // <copyright file="OdbcEnvironment.cs" company="Microsoft">
   3 //      Copyright (c) Microsoft Corporation.  All rights reserved.
   4 // </copyright>
   5 // <owner current="true" primary="true">Microsoft</owner>
   6 // <owner current="true" primary="false">Microsoft</owner>
   7 //------------------------------------------------------------------------------
   8
   9 using System;
  10 using System.Data;
  11 using System.Data.Common;
  12 using System.Threading;
  13
  14
  15 namespace System.Data.Odbc {
  16     sealed internal class OdbcEnvironment {
  17         static private object _globalEnvironmentHandle;
  18         static private object _globalEnvironmentHandleLock = new object();
  19
  20         private OdbcEnvironment () {}  // default const.
  21
  22         static internal OdbcEnvironmentHandle GetGlobalEnvironmentHandle() {
  23             OdbcEnvironmentHandle globalEnvironmentHandle = _globalEnvironmentHandle as OdbcEnvironmentHandle;
  24             if(null == globalEnvironmentHandle) {
  25                 ADP.CheckVersionMDAC(true);
  26
  27                 lock(_globalEnvironmentHandleLock) {
  28                     globalEnvironmentHandle = _globalEnvironmentHandle as OdbcEnvironmentHandle;
  29                     if(null == globalEnvironmentHandle) {
  30                         globalEnvironmentHandle = new OdbcEnvironmentHandle();
  31                         _globalEnvironmentHandle = globalEnvironmentHandle;
  32                     }
  33                 }
  34             }
  35             return globalEnvironmentHandle;
  36         }
  37
  38         static internal void ReleaseObjectPool() {
  39             object globalEnvironmentHandle = Interlocked.Exchange(ref _globalEnvironmentHandle, null);
  40             if(null != globalEnvironmentHandle) {
  41                 (globalEnvironmentHandle as OdbcEnvironmentHandle).Dispose(); // internally refcounted so will happen correctly
  42             }
  43         }
  44     }
  45 }
  46