win32_mutex.h

#ifndef WIN32_MUTEX_H
#define WIN32_MUTEX_H

#include <windows.h>

/* NOTE: In order to allow proper copying, I have to use pointers to
   CRITICAL_SECTION objects, so I decided I might as well use dynamic
   allocation.  I don't think we'll be creating that many mutexes
   anyway.  */

class Mutex
{
public:
  /* default constructor (creates an unlocked mutex) */
  Mutex (void)
    {
      mutex = new CRITICAL_SECTION;
      InitializeCriticalSection (mutex);
      refs = new int;
      *refs = 1;
    }

  /* copy constructor */
  Mutex (const Mutex& m)
    {
      mutex = m.mutex;
      refs = m.refs;
      (*refs)++; /* <-- FIXME: race condition */
    }

  /* assignment operator */
  Mutex& operator = (const Mutex& m)
    {
      (*refs)--;
      if (*refs == 0)
        {
          delete refs;
          DeleteCriticalSection (mutex);
          delete mutex;
        }

      mutex = m.mutex;
      refs = m.refs;
      (*refs)++;
          return *(this);
    }

  /* lock the mutex */
  void Lock (void)
    {
      EnterCriticalSection (mutex);
    }

  /* unlock the mutex */
  void Unlock (void)
    {
      LeaveCriticalSection (mutex);
    }

  /* destructor */
  ~Mutex (void)
    {
      (*refs)--;
      if (*refs == 0)
        {
          delete refs;
          DeleteCriticalSection (mutex);
          delete mutex;
        }
    }

private:
  /* reference count */
  int *refs;

  /* the mutex */
  CRITICAL_SECTION *mutex;
};

#endif

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