D:/git-itom/sources/itom/DataObject/readWriteLock.h

/* ********************************************************************
    itom software
    URL: http://www.uni-stuttgart.de/ito
    Copyright (C) 2013, Institut für Technische Optik (ITO),
    Universität Stuttgart, Germany

    This file is part of itom and its software development toolkit (SDK).

    itom is free software; you can redistribute it and/or modify it
    under the terms of the GNU Library General Public Licence as published by
    the Free Software Foundation; either version 2 of the Licence, or (at
    your option) any later version.
   
    In addition, as a special exception, the Institut für Technische
    Optik (ITO) gives you certain additional rights.
    These rights are described in the ITO LGPL Exception version 1.0,
    which can be found in the file LGPL_EXCEPTION.txt in this package.

    itom 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 Library
    General Public Licence for more details.

    You should have received a copy of the GNU Library General Public License
    along with itom. If not, see <http://www.gnu.org/licenses/>.
*********************************************************************** */

#ifndef READWRITELOCK
#define READWRITELOCK

// Use Window or Posix
//#if defined (_WINDOWS) || defined (WIN32)
#ifdef WIN32
     #include <windows.h>
#else
     #ifndef POSIX
//          #warning POSIX will be used (but you did not define it)
     #endif
     #include <pthread.h>
#endif

#ifdef WIN32
//#if defined _WINDOWS || defined WIN32

    class ReadWriteLock
    {
    private:

        ReadWriteLock(const ReadWriteLock &) {}

        int nrOfReaders;                
        int status;                     
        bool writeGelocked;
        CRITICAL_SECTION mAtomicOp;     
        CRITICAL_SECTION mReadLock;     
        CRITICAL_SECTION mWriteLock;    

    public:

        ReadWriteLock(int lockStatus = 0) : nrOfReaders(0), status(0), writeGelocked(false)
        {
            InitializeCriticalSection(&mAtomicOp);
            InitializeCriticalSection(&mReadLock);
            InitializeCriticalSection(&mWriteLock);

            if(lockStatus == -1)
            {
                lockWrite();
                status = -1;
            }
            else if(lockStatus > 0)
            {
                lockRead(lockStatus);
                status = lockStatus;
            }
        };


        ~ReadWriteLock()
        {
            TryEnterCriticalSection(&mAtomicOp);
            LeaveCriticalSection(&mAtomicOp);
            DeleteCriticalSection(&mAtomicOp);
            TryEnterCriticalSection(&mReadLock);
            LeaveCriticalSection(&mReadLock);
            DeleteCriticalSection(&mReadLock);
            TryEnterCriticalSection(&mWriteLock);
            LeaveCriticalSection(&mWriteLock);
            DeleteCriticalSection(&mWriteLock);
        };


        void lockRead(int increment = 1)
        {
            //if(!TryEnterCriticalSection(&mWriteLock))
            //{
            //    int i=1;
            //    EnterCriticalSection(&mWriteLock);
            //    std::cout << "try failed2" << std::endl;
            //}
            EnterCriticalSection(&mWriteLock);

            writeGelocked = true;
            EnterCriticalSection(&mAtomicOp);
            TryEnterCriticalSection(&mReadLock);
            nrOfReaders+= increment;
            status = nrOfReaders;
            LeaveCriticalSection(&mAtomicOp);
            LeaveCriticalSection(&mWriteLock);
            writeGelocked = false;
        }


        void lockWrite()
        {
            //if(!TryEnterCriticalSection(&mWriteLock))
            //{
            //    int i=1;
            //    EnterCriticalSection(&mWriteLock);
            //    std::cout << "try failed" << std::endl;
            //}
            EnterCriticalSection(&mWriteLock);

            writeGelocked = true;
            EnterCriticalSection(&mReadLock);
            EnterCriticalSection(&mAtomicOp);
            status = -1;
            LeaveCriticalSection(&mAtomicOp);
        }


        void unlock()
        {
            EnterCriticalSection(&mAtomicOp);
            if(nrOfReaders == 0)
            {
                while(mReadLock.RecursionCount > 0) LeaveCriticalSection(&mReadLock);
                while(mWriteLock.RecursionCount > 0) LeaveCriticalSection(&mWriteLock);
                writeGelocked = false;
                status = 0;
            }
            else
            {
                if(nrOfReaders > 0)  nrOfReaders--;
                status = nrOfReaders;
                if(nrOfReaders <= 0)
                {
                    while(mReadLock.RecursionCount > 0) LeaveCriticalSection(&mReadLock);
                }
            }
            LeaveCriticalSection(&mAtomicOp);
        }


        void _unlock(int value)
        {
            EnterCriticalSection(&mAtomicOp);
            if(value == -1)
            {
                TryEnterCriticalSection(&mReadLock);
                while(mReadLock.RecursionCount > 0) LeaveCriticalSection(&mReadLock);
                TryEnterCriticalSection(&mWriteLock);
                while(mWriteLock.RecursionCount > 0) LeaveCriticalSection(&mWriteLock);
                writeGelocked = false;
                status = 0;
            }
            else
            {
                nrOfReaders -= value;
                if(nrOfReaders <= 0)
                {
                    nrOfReaders = 0;
                    TryEnterCriticalSection(&mReadLock);
                    while(mReadLock.RecursionCount > 0) LeaveCriticalSection(&mReadLock);
                }
                status = nrOfReaders;
            }
            LeaveCriticalSection(&mAtomicOp);
        }


        inline int getLockStatus() const { return status; }
    };

#else

    class ReadWriteLock
    {
        public:

            ReadWriteLock(int lockStatus = 0) : nrOfReaders(0), status(0), writeGelocked(false)
            {
                pthread_mutexattr_t attr;
                pthread_mutexattr_init(&attr);
                pthread_mutexattr_settype(&attr,PTHREAD_MUTEX_RECURSIVE);
                pthread_mutex_init(&mAtomicOp,&attr);
                pthread_mutex_init(&mReadLock,&attr);
                pthread_mutex_init(&mWriteLock,&attr);
                pthread_mutexattr_destroy(&attr);

                if(lockStatus == -1)
                {
                    lockWrite();
                    status = -1;
                }
                else if(lockStatus > 0)
                {
                    lockRead(lockStatus);
                    status = lockStatus;
                }
            }


            ~ReadWriteLock()
            {
                pthread_mutex_trylock(&mAtomicOp);
                pthread_mutex_unlock(&mAtomicOp);
                pthread_mutex_destroy(&mAtomicOp);
                pthread_mutex_trylock(&mReadLock);
                pthread_mutex_unlock(&mReadLock);
                pthread_mutex_destroy(&mReadLock);
                pthread_mutex_trylock(&mWriteLock);
                pthread_mutex_unlock(&mWriteLock);
                pthread_mutex_destroy(&mWriteLock);
            }


            void lockRead(int increment = 1)
            {
                pthread_mutex_lock(&mWriteLock);
                pthread_mutex_lock(&mAtomicOp);
                pthread_mutex_trylock(&mReadLock);
                nrOfReaders+=increment;
                status = nrOfReaders;
                pthread_mutex_unlock(&mAtomicOp);
                pthread_mutex_unlock(&mWriteLock);
            }


            void lockWrite()
            {
                pthread_mutex_lock(&mWriteLock);
                pthread_mutex_lock(&mReadLock);
                pthread_mutex_lock(&mAtomicOp);
                status = -1;
                pthread_mutex_unlock(&mAtomicOp);
            }


            void unlock()
            {
                pthread_mutex_lock(&mAtomicOp);
                if(nrOfReaders == 0)
                {
                    pthread_mutex_unlock(&mReadLock);
                    pthread_mutex_unlock(&mWriteLock);
                    status = 0;
                }
                else
                {
                    if(nrOfReaders > 0)  nrOfReaders--;
                    status = nrOfReaders;
                    if(nrOfReaders <= 0) pthread_mutex_unlock(&mReadLock);
                }
                pthread_mutex_unlock(&mAtomicOp);
            }


            void _unlock(int value)
            {
                pthread_mutex_lock(&mAtomicOp);
                if(value == -1)
                {
                    pthread_mutex_trylock(&mReadLock);
                    pthread_mutex_unlock(&mReadLock);
                    pthread_mutex_trylock(&mWriteLock);
                    pthread_mutex_unlock(&mWriteLock);
                    status = 0;
                }
                else
                {
                    nrOfReaders -= value;
                    if(nrOfReaders <= 0)
                    {
                        nrOfReaders = 0;
                        pthread_mutex_trylock(&mReadLock);
                        pthread_mutex_unlock(&mReadLock);
                    }
                    status = nrOfReaders;
                }
                pthread_mutex_unlock(&mAtomicOp);
            }


            inline int getLockStatus() const { return status; }

        private:

            ReadWriteLock(const ReadWriteLock &) {}

            int nrOfReaders;                
            int status;                     
            bool writeGelocked;
            pthread_mutex_t mAtomicOp;     
            pthread_mutex_t mReadLock;     
            pthread_mutex_t mWriteLock;    
    };

#endif



#endif