/********************************************************************
**                Image Component Library (ICL)                    **
**                                                                 **
** Copyright (C) 2006-2013 CITEC, University of Bielefeld          **
**                         Neuroinformatics Group                  **
** Website: www.iclcv.org and                                      **
**          http://opensource.cit-ec.de/projects/icl               **
**                                                                 **
** File   : ICLUtils/src/ICLUtils/MultiThreader.cpp                **
** Module : ICLUtils                                               **
** Authors: Christof Elbrechter                                    **
**                                                                 **
**                                                                 **
** GNU LESSER GENERAL PUBLIC LICENSE                               **
** This file may be used under the terms of the GNU Lesser General **
** Public License version 3.0 as published by the                  **
**                                                                 **
** Free Software Foundation and appearing in the file LICENSE.LGPL **
** included in the packaging of this file.  Please review the      **
** following information to ensure the license requirements will   **
** be met: http://www.gnu.org/licenses/lgpl-3.0.txt                **
**                                                                 **
** The development of this software was supported by the           **
** Excellence Cluster EXC 277 Cognitive Interaction Technology.    **
** The Excellence Cluster EXC 277 is a grant of the Deutsche       **
** Forschungsgemeinschaft (DFG) in the context of the German       **
** Excellence Initiative.                                          **
**                                                                 **
********************************************************************/

#include <ICLUtils/MultiThreader.h>
#include <ICLUtils/Macros.h>
#include <ICLUtils/Thread.h>
#include <ICLUtils/Semaphore.h>
#include <ICLUtils/Mutex.h>


namespace icl{
  namespace utils{
    class MultiThreader::MTWorkThread : public Thread{
    public:
      // {{{ open
  
      MTWorkThread(Semaphore *sem1, Semaphore *sem2, Semaphore *semDone):work(0),m_bCurr(0){
        // {{{ open
  
        m_apoSems[0] = sem1;
        m_apoSems[1] = sem2;
        m_poSemDone = semDone;
        m_bEnd = false;
      }
  
      // }}}
      
      ~MTWorkThread(){
        // {{{ open
  
        m_oWorkMutex.lock();
        work = 0;
        m_oWorkMutex.unlock();
        m_bEnd = true;
        m_apoSems[m_bCurr]->release(1);
      }
  
      // }}}
      
      virtual void run(){
        // {{{ open
  
        while(!m_bEnd){
          m_apoSems[m_bCurr]->acquire(1);
          Thread::usleep(0);
          m_oWorkMutex.lock();
          Thread::usleep(0);
          if(work){
  
            work->perform();
          }
          Thread::usleep(0);
          m_oWorkMutex.unlock();
          Thread::usleep(0);
          m_poSemDone->release(1);
          Thread::usleep(0);
          m_bCurr = !m_bCurr;
          
          Thread::usleep(0);
        }
      }
  
      // }}}
      
      void setWork(MultiThreader::Work *work){
        // {{{ open
  
        m_oWorkMutex.lock();
        this->work = work;
        m_oWorkMutex.unlock();
      }
  
      // }}}
      
    private:
      MultiThreader::Work *work;
      Semaphore *m_apoSems[2];
      Semaphore *m_poSemDone;
      Mutex m_oWorkMutex;
      bool m_bCurr;
      bool m_bEnd;
    };
  
    // }}}
  
    class MultiThreaderImpl{
      // {{{ open
  
    public:
      MultiThreaderImpl(int nThreads):
        // {{{ open
  
        m_iNThreads(nThreads),m_bCurr(0){
        m_vecThreads.resize(nThreads);
        
        m_apoSems[0] = new Semaphore(nThreads);
        m_apoSems[1] = new Semaphore(nThreads);
        m_poDoneSem = new Semaphore(nThreads);
        
        
        m_apoSems[0]->acquire(nThreads);
        m_apoSems[1]->acquire(nThreads);
        m_poDoneSem->acquire(nThreads);
        
        for(int i=0;i<nThreads;++i){
          m_vecThreads[i] = new MultiThreader::MTWorkThread(m_apoSems[0],m_apoSems[1],m_poDoneSem);
          m_vecThreads[i]->start();
        }
      }
  
      // }}}
      ~MultiThreaderImpl(){
        // {{{ open
  
        for(int i=0;i<m_iNThreads;++i){
          delete m_vecThreads[i];
        }
        delete m_apoSems[0];
        delete m_apoSems[1];
      }
  
      // }}}
      
      inline void apply(MultiThreader::WorkSet &ws){
        // {{{ open
  
        ICLASSERT_RETURN((int)ws.size() == m_iNThreads);
        
        /// arm the threads
        for(unsigned int i=0;i<ws.size();i++){
          m_vecThreads[i]->setWork(ws[i]);
        }
        
        m_apoSems[m_bCurr]->release(m_iNThreads);
        m_poDoneSem->acquire(m_iNThreads);
        
        /// defuse the threads !
        for(unsigned int i=0;i<ws.size();i++){
          m_vecThreads[i]->setWork(0);
        }
        
        m_bCurr =! m_bCurr;
      }
  
      // }}}
      
      inline int getNumThreads() const { 
        // {{{ open
  
        return m_iNThreads;
      }
  
      // }}}
  
    private:
      int m_iNThreads;
      std::vector<MultiThreader::MTWorkThread*> m_vecThreads;
      Semaphore *m_apoSems[2];
      Semaphore *m_poDoneSem;
      Mutex m_oSemMutex;
      bool m_bCurr;
  
    };
  
    // }}}
  
    void MultiThreaderImplDelOp::delete_func( MultiThreaderImpl *impl){
      // {{{ open
  
      ICL_DELETE( impl);
    }
  
    // }}}
    
    MultiThreader::MultiThreader():
      // {{{ open
  
      ShallowCopyable<MultiThreaderImpl,MultiThreaderImplDelOp>(0){
    
    }
  
    // }}}
  
    MultiThreader::MultiThreader(int nThreads):
      // {{{ open
  
      ShallowCopyable<MultiThreaderImpl,MultiThreaderImplDelOp>(new MultiThreaderImpl(nThreads)){
      
    }
  
    // }}}
    
    void MultiThreader::operator()(MultiThreader::WorkSet &ws){
      // {{{ open
      ICLASSERT_RETURN(!isNull());
      impl->apply(ws);
    }
  
    // }}}
  
    int MultiThreader::getNumThreads() const{
      // {{{ open
  
      ICLASSERT_RETURN_VAL(!isNull(),0);
      return impl->getNumThreads();
    }
  
    // }}}
  } // namespace utils
}