interprocess/Interprocess_sync_windows_emulation.txt

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named_semaphore
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- Use a file for file lifetime semantics (create, open, unlink...)
- Create on demand (open or create) a windows named semaphore with all access (permissions are on the file).
- Use file id with a "prefix bips." to construct the mutex "Global\prefix bips.XXXXXXXXXXXXXXXXXXX"
- Add getvalue as implemented by cygwin
- Write sem status to file at file close. Use native file locking to serialize.
- See cygwin-1.7.5-1\winsup\cygwin\posix_ipc.cc and thread.cc




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named_mutex
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- Don't serialize

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named_condition
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Process shared resources. Use lock reduced versions?
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what about fast_semaphore (http://www.tech-archive.net/Archive/Development/microsoft.public.win32.programmer.kernel/2005-03/0041.html):

class fast_semaphore
{

public:

    fast_semaphore( LONG init )
        : m_state( init ),
          m_waitset( CreateSemaphore( 0, 0, LONG_MAX, 0 ) )
    { if ( ! m_waitset ) { throw; } }

    ~fast_semaphore()
    { if ( ! CloseHandle( m_waitset ) ) { abort(); } }

public:

    void inc()
    {
        if ( InterlockedIncrement( &m_state ) < 1 )
        {
            if ( ! ReleaseSemaphore( m_waitset, 1, 0 ) )
            {
                throw;
            }
        }
    }

    void dec()
    {
        if ( InterlockedDecrement( &m_state ) < 0 )
        {
            if ( WaitForSingleObject( m_waitset, INFINITE ) !=
WAIT_OBJECT_0 )
            {
                throw;
            }
        }
    }

private:

    volatile LONG m_state;
    HANDLE m_waitset;

};

class mutex_from_semaphore
{

public:

    mutex_from_semaphore() : m_waitset( 1 ) {}

public:

    void enter() { m_waitset.dec(); }
    void leave() { m_waitset.inc(); }

private:

    fast_semaphore m_waitset;

}; 

Or see Java implemenation (http://www.google.com/codesearch/p?hl=es#5qy3uURTOpU/trunk/JobRunner/src/org/ivoa/util/concurrent/FastSemaphore.java&q=%22fast%20semaphore%22&sa=N&cd=1&ct=rc&l=10)


For mutex, usefast mutex (see fast_mutex.h in cygwin): 


class fast_mutex
{
public:
  fast_mutex () :
    lock_counter (0), win32_obj_id (0)
  {
  }

  ~fast_mutex ()
  {
    if(win32_obj_id)
      CloseHandle (win32_obj_id);
  }

  bool init ()
  {
    lock_counter = 0;
    win32_obj_id = ::CreateEvent (&sec_none_nih, false, false, NULL);
    if (!win32_obj_id)
      {
	debug_printf ("CreateEvent failed. %E");
	return false;
      }
    return true;
  }

  void lock ()
  {
    if (InterlockedIncrement ((long *) &lock_counter) != 1)
      cancelable_wait (win32_obj_id, INFINITE, cw_no_cancel, cw_sig_resume);
  }

  void unlock ()
  {
    if (InterlockedDecrement ((long *) &lock_counter))
      ::SetEvent (win32_obj_id);
  }

private:
  unsigned long lock_counter;
  HANDLE win32_obj_id;
};


Or this one (http://www.tech-archive.net/Archive/Development/microsoft.public.win32.programmer.kernel/2005-03/0067.html):


class fast_mutex
{

public:

    fast_mutex
        : m_state( 0 ),
          m_waitset( CreateEvent( 0, FALSE, FALSE 0 ) )
    { if ( ! m_waitset ) { throw; } }

    ~fast_mutex
    { if ( ! CloseHandle( m_waitset ) ) { abort(); } }

public:

    void enter
    {
        if ( InterlockedExchange( &m_state, 1 ) )
        {
            _asm pause; /* masm */

            while ( InterlockedExchange( &m_state, 2 ) )
            {
                if ( WaitForSingleObject
                        ( m_waitset,
                          INFINITE ) !=
                     WAIT_OBJECT_0 )
                {
                    throw;
                }
            }
        }
    }

    void leave()
    {
        if ( InterlockedExchange( &m_state, 0 ) == 2 )
        {
            if ( ! SetEvent( m_waitset ) )
            {
                throw;
            }
        }
    }

private:

    volatile LONG m_state;
    HANDLE m_waitset;

};