StdCriticalSectionInternal.h

// CTryEnterCS
//
// A ::TryEnterCriticalSection type thing that works on 9x
//
// Written by Olan Patrick Barnes (patrick@mfcfree.com)
// Copyright (c) 2001 Olan Patrick Barnes
//
// This code may be used in compiled form in any way you desire. This
// file may be redistributed by any means PROVIDING it is 
// not sold for profit without the authors written consent, and 
// providing that this notice and the authors name is included. 
//
// This file is provided "as is" with no expressed or implied warranty.
// The author accepts no liability if it causes any damage to you or your
// computer whatsoever.
//
// Description:
//
// ::TryEnterCriticalSection() is only available on NT platforms, and you
// may need to support 9x.  This is a custom critical section class that
// allows for "try-enter" logic.  It operates 100% in user mode (this
// class does not use expensive kernel objects), making use of the
// ::InterlockedExchange() and ::GetCurrentThreadId() API's.
//

#pragma once

namespace StdUtils
{

typedef enum {Locked, Unlocked} LockState;
    
class CStdCriticalSectionInternal : public CStdCriticalSection
{
protected:

#ifdef WIN32
    boost::atomic<LockState> m_iBusy;
#else
    std::atomic<int> m_iBusy;
#endif

    boost::thread::id m_dwOwner;

    bool m_bOwned;

    ULONG m_ulRefCnt;

#pragma region InternalLocker

   class InternalLocker
   {
   protected:
      //Do not allow copy constructor or copy operator

      InternalLocker();

      InternalLocker(const InternalLocker& src);

      const InternalLocker& operator=(const InternalLocker& src);

#ifdef WIN32
          boost::atomic<LockState> &m_iBusy;
#else
          std::atomic<int> &m_iBusy;
#endif

   public:

#ifdef WIN32
      explicit InternalLocker(boost::atomic<LockState> &iBusy);
#else
      explicit InternalLocker(std::atomic<int> &iBusy);
#endif

          ~InternalLocker();
   };
   friend class InternalLocker;

#pragma endregion

public:

   CStdCriticalSectionInternal();
   ~CStdCriticalSectionInternal();

   bool TryEnter();
   bool Enter(long lMilliTimeout = -1);
   bool Leave();
};

}                               //StdUtils