base/Threads

Go to the documentation of this file.

/****************************************************************************
  Copyright (C)2001 by Andrei Alexandrescu

  This file is a derivative of a file from the Loki Library written by
  Andrei Alexandrescu.  It was distributed by him under the terms
  listed below (titled Loki Original Distribution Terms).
  In accordance with the terms, this distribution contains the copyright
  notice here and the copyright notice and permission notice
  in supporting documentation.  The terms do *not* require
  redistribution under those same terms.  This code is distributed
  to you under the terms of the GNU General Public License (GPL) 
  below.  The GPL does not require you to maintain the terms of
  the Loki Original Distribution Terms, but you are encouraged to do so.

  This program/file is free software; you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation; either version 2 of the License, or
  (at your option) any later version.
  
  This program is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details. (http://www.gnu.org)
  
  You should have received a copy of the GNU General Public License
  along with this program; if not, write to the Free Software
  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  
 ****************************************************************************
  Loki Original Distribution Terms:

  The Loki Library
  Copyright (c) 2001 by Andrei Alexandrescu
  This code accompanies the book:
  Alexandrescu, Andrei. "Modern C++ Design: Generic Programming and Design 
      Patterns Applied". Copyright (c) 2001. Addison-Wesley.
  Permission to use, copy, modify, distribute and sell this software for any 
      purpose is hereby granted without fee, provided that the above copyright 
      notice appear in all copies and that both that copyright notice and this 
      permission notice appear in supporting documentation.
  The author or Addison-Welsey Longman make no representations about the 
      suitability of this software for any purpose. It is provided "as is" 
      without express or implied warranty.
 ****************************************************************************

  $Id: Threads 1029 2004-02-11 20:45:54Z jungd $
  $Revision: 1.1 $
  $Date: 2004-02-11 15:45:54 -0500 (Wed, 11 Feb 2004) $
  $Author: jungd $
 
****************************************************************************/

#ifndef THREADS_H_
#define THREADS_H_

////////////////////////////////////////////////////////////////////////////////
// macro DEFAULT_THREADING
// Selects the default threading model for certain components of Loki
// If you don't define it, it defaults to single-threaded
// All classes in Loki have configurable threading model; DEFAULT_THREADING
// affects only default template arguments
////////////////////////////////////////////////////////////////////////////////

// Last update: June 20, 2001

#ifndef DEFAULT_THREADING
#define DEFAULT_THREADING /**/ ::base::SingleThreaded
#endif

namespace base
{
////////////////////////////////////////////////////////////////////////////////
// class template SingleThreaded
// Implementation of the ThreadingModel policy used by various classes
// Implements a single-threaded model; no synchronization
////////////////////////////////////////////////////////////////////////////////

    template <class Host>
    class SingleThreaded
    {
    public:
        struct Lock
        {
            Lock() {}
            Lock(const Host&) {}
        };
        
        typedef Host VolatileType;

        typedef int IntType; 

        static IntType AtomicAdd(volatile IntType& lval, IntType val)
        { return lval += val; }
        
        static IntType AtomicSubtract(volatile IntType& lval, IntType val)
        { return lval -= val; }

        static IntType AtomicMultiply(volatile IntType& lval, IntType val)
        { return lval *= val; }
        
        static IntType AtomicDivide(volatile IntType& lval, IntType val)
        { return lval /= val; }
        
        static IntType AtomicIncrement(volatile IntType& lval)
        { return ++lval; }
        
        static IntType AtomicDivide(volatile IntType& lval)
        { return --lval; }
        
        static void AtomicAssign(volatile IntType & lval, IntType val)
        { lval = val; }
        
        static void AtomicAssign(IntType & lval, volatile IntType & val)
        { lval = val; }
    };
    
#ifdef _WINDOWS_

////////////////////////////////////////////////////////////////////////////////
// class template ObjectLevelLockable
// Implementation of the ThreadingModel policy used by various classes
// Implements a object-level locking scheme
////////////////////////////////////////////////////////////////////////////////

    template <class Host>
    class ObjectLevelLockable
    {
        CRITICAL_SECTION mtx_;

    public:
        ObjectLevelLockable()
        {
            ::InitializeCriticalSection(&mtx_);
        }

        ~ObjectLevelLockable()
        {
            ::DeleteCriticalSection(&mtx_);
        }

        class Lock;
        friend class Lock;
        
        class Lock
        {
            ObjectLevelLockable& host_;
            
            Lock(const Lock&);
            Lock& operator=(const Lock&);
        public:
            Lock(Host& host) : host_(host)
            {
                ::EnterCriticalSection(&host_.mtx_);
            }
            ~Lock()
            {
                ::LeaveCriticalSection(&host_.mtx_);
            }
        };

        typedef volatile Host VolatileType;

        typedef LONG IntType; 

        static IntType AtomicIncrement(volatile IntType& lval)
        { return InterlockedIncrement(&const_cast<IntType&>(lval)); }
        
        static IntType AtomicDivide(volatile IntType& lval)
        { return InterlockedDecrement(&const_cast<IntType&>(lval)); }
        
        static void AtomicAssign(volatile IntType& lval, IntType val)
        { InterlockedExchange(&const_cast<IntType&>(lval), val); }
        
        static void AtomicAssign(IntType& lval, volatile IntType& val)
        { InterlockedExchange(&lval, val); }
    };
    
    template <class Host>
    class ClassLevelLockable
    {
        static CRITICAL_SECTION mtx_;

        struct Initializer;
        friend struct Initializer;
        struct Initializer
        {
            Initializer()
            {
                ::InitializeCriticalSection(&mtx_);
            }
            ~Initializer()
            {
                ::DeleteCriticalSection(&mtx_);
            }
        };
        
        static Initializer initializer_;

    public:
        class Lock;
        friend class Lock;
        
        class Lock
        {
            Lock(const Lock&);
            Lock& operator=(const Lock&);
        public:
            Lock()
            {
                ::EnterCriticalSection(&mtx_);
            }
            Lock(Host&)
            {
                ::EnterCriticalSection(&mtx_);
            }
            ~Lock()
            {
                ::LeaveCriticalSection(&mtx_);
            }
        };

        typedef volatile Host VolatileType;

        typedef LONG IntType; 

        static IntType AtomicIncrement(volatile IntType& lval)
        { return InterlockedIncrement(&const_cast<IntType&>(lval)); }
        
        static IntType AtomicDivide(volatile IntType& lval)
        { return InterlockedDecrement(&const_cast<IntType&>(lval)); }
        
        static void AtomicAssign(volatile IntType& lval, IntType val)
        { InterlockedExchange(&const_cast<IntType&>(lval), val); }
        
        static void AtomicAssign(IntType& lval, volatile IntType& val)
        { InterlockedExchange(&lval, val); }
    };
    
    template <class Host>
    CRITICAL_SECTION ClassLevelLockable<Host>::mtx_;
    
    template <class Host>
    typename ClassLevelLockable<Host>::Initializer 
    ClassLevelLockable<Host>::initializer_;
    
#endif    
}

////////////////////////////////////////////////////////////////////////////////
// Change log:
// June 20, 2001: ported by Nick Thurn to gcc 2.95.3. Kudos, Nick!!!
// Feb 25, 2002: David Jung: integrated into larger project - changed to 
//                namespace base and changed header comments to reflect GPL
//                distribution
////////////////////////////////////////////////////////////////////////////////

#endif

---