[boost] Re: [Boost.Thread] mutex Win32 implementation changes

From: Alexander Terekhov (terekhov_at_[hidden])
Date: 2004-07-20 14:06:38

Peter Dimov wrote:
[...]
> > I have PS/2 Model 80 (with 64 Megs) "tank" at home (in addition to
> > A31p ThinkPad ;-) ).
> 
> He he. OK, if you had CAS (PS/2 Model 70 486) how would you do it?

Ok, you owe me a "Blue Lightening" processor upgrade. ;-) How about 

  void lock() throw() {
    while (int lock_status = m_lock_status.cas(0, 1, msync::ddacq))
      if (lock_status < 0 || m_lock_status.cas(1,-1, msync::ddacq))
        m_retry_event.wait();
  } 

  bool trylock() throw() {
    return !m_lock_status.cas(0, 1, msync::acq);
  }

  bool timedlock(absolute_timeout const & timeout) throw() {
    while (int lock_status = m_lock_status.cas(0, 1, msync::ddacq))
      if (lock_status < 0 || m_lock_status.cas(1,-1, msync::ddacq))
        if (!m_retry_event.timedwait(timeout)) m_retry_event.set(), 
          return !m_lock_status.swap(1, msync::acq);
    return true;
  }

  void unlock() throw() {
    if (m_lock_status.swap(0, msync::rel) < 0) 
      m_retry_event.set();
  } 

<?>

regards,
alexander.