Block

/* -*-c++-*- OpenThreads - Copyright (C) 1998-2007 Robert Osfield
 *
 * This library is open source and may be redistributed and/or modified under
 * the terms of the OpenSceneGraph Public License (OSGPL) version 0.0 or
 * (at your option) any later version.  The full license is in LICENSE file
 * included with this distribution, and on the openscenegraph.org website.
 *
 * This library 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
 * OpenSceneGraph Public License for more details.
*/

#ifndef _OPENTHREADS_BLOCK_
#define _OPENTHREADS_BLOCK_

#include <OpenThreads/Thread>
#include <OpenThreads/Barrier>
#include <OpenThreads/Condition>
#include <OpenThreads/ScopedLock>

namespace OpenThreads {

/** Block is a block that can be used to halt a thread that is waiting another thread to release it.*/
class Block 
{
    public:
    
        Block():
            _released(false) {}

        ~Block()
        {
            release();
        }

        inline bool block()
        {
            ScopedLock<OpenThreads::Mutex> mutlock(_mut);
            if( !_released )
            {
                return _cond.wait(&_mut)==0;
            }
            else
            {
                return true;
            }
        }

        inline bool block(unsigned long timeout)
        {
            ScopedLock<OpenThreads::Mutex> mutlock(_mut);
            if( !_released )
            {
                return _cond.wait(&_mut, timeout)==0;
            }
            else
            {
                return true;
            }
        }

        inline void release()
        {
            ScopedLock<OpenThreads::Mutex> mutlock(_mut);
            if (!_released)
            {
                _released = true;
                _cond.broadcast();
            }
        }

        inline void reset()
        {
            ScopedLock<OpenThreads::Mutex> mutlock(_mut);
            _released = false;
        }
        
        inline void set(bool doRelease)
        {
            if (doRelease!=_released)
            {
                if (doRelease) release();
                else reset();
            }
        }

    protected:

        Mutex _mut;
        Condition _cond;
        bool _released;

    private:

        Block(const Block&) {}
};

/** BlockCount is a block that can be used to halt a thread that is waiting for a specified number of operations to be completed.*/
class BlockCount 
{
    public:
    
        BlockCount(unsigned int blockCount):
            _blockCount(blockCount),
            _currentCount(0) {}

        ~BlockCount()
        {
            _blockCount = 0;
            release();
        }

        inline void completed()
        {
            OpenThreads::ScopedLock<OpenThreads::Mutex> mutlock(_mut);
            if (_currentCount>0)
            {
                --_currentCount;

                if (_currentCount==0)
                {
                    // osg::notify(osg::NOTICE)<<"Released"<<std::endl;
                    _cond.broadcast();
                }
            }
        }

        inline void block()
        {
            OpenThreads::ScopedLock<OpenThreads::Mutex> mutlock(_mut);
            if (_currentCount)
                _cond.wait(&_mut);
        }
        
        inline void reset()
        {
            OpenThreads::ScopedLock<OpenThreads::Mutex> mutlock(_mut);
            if (_currentCount!=_blockCount)
            {
                if (_blockCount==0) _cond.broadcast();
                _currentCount = _blockCount;
            }
        }

        inline void release()
        {
            OpenThreads::ScopedLock<OpenThreads::Mutex> mutlock(_mut);
            if (_currentCount)
            {
                _currentCount = 0;
                _cond.broadcast();
            }
        }

        inline void setBlockCount(unsigned int blockCount) { _blockCount = blockCount; }
        
        inline unsigned int getBlockCount() const { return _blockCount; }
        
        inline unsigned int getCurrentCount() const { return _currentCount; }

    protected:

        OpenThreads::Mutex _mut;
        OpenThreads::Condition _cond;
        unsigned int _blockCount;
        unsigned int _currentCount;

    private:
    
        BlockCount(const BlockCount&) {}

};

}

#endif