mcs/class/referencesource/System.Workflow.Runtime/ExecutorLocksHeldException.cs

   1 // ****************************************************************************
   2 // Copyright (C) 2000-2001 Microsoft Corporation.  All rights reserved.
   3 //
   4 // CONTENTS
   5 //     Workflow Base exception class
   6 //
   7 // DESCRIPTION
   8 //     Base class for WINOE Runtime engine exception
   9 //
  10 // REVISIONS
  11 // Date          Ver     By           Remarks
  12 // ~~~~~~~~~~    ~~~     ~~~~~~~~     ~~~~~~~~~~~~~~
  13 // 03/08/01      1.0     Microsoft       Created.
  14 // ****************************************************************************
  15 using System;
  16 using System.Runtime.Serialization;
  17 using System.Security.Permissions;
  18 using System.Collections.Generic;
  19 using System.Globalization;
  20 using System.Threading;
  21 using System.Workflow;
  22 using System.Workflow.Runtime;
  23 using System.Workflow.ComponentModel;
  24
  25 namespace System.Workflow.Runtime
  26 {
  27     /*
  28      * The Unload() method has been changed so that
  29      * any Unload requests made while in the middle of an atomic
  30      * transaction wait for the atomic transaction to complete.
  31      * This makes use of an ManualResetEvent. Unload() waits on the event:
  32      *      theEvent.WaitOne()
  33      * But waiting with the executor and scheduler locks held
  34      * will block everything else.
  35      *
  36      * The solution is to have a custom internal exception class that has the
  37      * ManualResetEvent as an internal property. If Unload() finds itself in the middle
  38      * of an atomic transaction, it throws the Exception. The Exception is propogated upwards
  39      * until we reach the method that was the first to grab the executor lock.
  40      *
  41      * We then drop that lock and wait on the event handle. As soon as the handle is
  42      * Set() by DisposeTransaction(), we grab the executor lock and do everything all over.
  43      */
  44
  45     internal class ExecutorLocksHeldException : Exception
  46     {
  47         private ManualResetEvent handle;
  48
  49         public ExecutorLocksHeldException(ManualResetEvent handle)
  50         {
  51             this.handle = handle;
  52         }
  53
  54         internal ManualResetEvent Handle
  55         {
  56             get
  57             {
  58                 return handle;
  59             }
  60         }
  61     }
  62 }