opm-simulators/opm/models/parallel/threadedentityiterator.hh
2020-06-10 13:49:42 +02:00

102 lines
2.9 KiB
C++

// -*- mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
// vi: set et ts=4 sw=4 sts=4:
/*
This file is part of the Open Porous Media project (OPM).
OPM 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.
OPM 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.
You should have received a copy of the GNU General Public License
along with OPM. If not, see <http://www.gnu.org/licenses/>.
Consult the COPYING file in the top-level source directory of this
module for the precise wording of the license and the list of
copyright holders.
*/
/*!
* \file
* \copydoc Opm::ThreadedEntityIterator
*/
#ifndef EWOMS_THREADED_ENTITY_ITERATOR_HH
#define EWOMS_THREADED_ENTITY_ITERATOR_HH
#include <thread>
#include <mutex>
namespace Opm {
/*!
* \brief Provides an STL-iterator like interface to iterate over the enties of a
* GridView in OpenMP threaded applications
*
* ATTENTION: This class must be instantiated in a sequential context!
*/
template <class GridView, int codim>
class ThreadedEntityIterator
{
using Entity = typename GridView::template Codim<codim>::Entity;
using EntityIterator = typename GridView::template Codim<codim>::Iterator;
public:
ThreadedEntityIterator(const GridView& gridView)
: gridView_(gridView)
, sequentialIt_(gridView_.template begin<codim>())
, sequentialEnd_(gridView.template end<codim>())
{ }
ThreadedEntityIterator(const ThreadedEntityIterator& other) = default;
// begin iterating over the grid in parallel
EntityIterator beginParallel()
{
mutex_.lock();
auto tmp = sequentialIt_;
if (sequentialIt_ != sequentialEnd_)
++sequentialIt_; // make the next thread look at the next element
mutex_.unlock();
return tmp;
}
// returns true if the last element was reached
bool isFinished(const EntityIterator& it) const
{ return it == sequentialEnd_; }
// make sure that the loop over the grid is finished
void setFinished()
{
mutex_.lock();
sequentialIt_ = sequentialEnd_;
mutex_.unlock();
}
// prefix increment: goes to the next element which is not yet worked on by any
// thread
EntityIterator increment()
{
mutex_.lock();
auto tmp = sequentialIt_;
if (sequentialIt_ != sequentialEnd_)
++sequentialIt_;
mutex_.unlock();
return tmp;
}
private:
GridView gridView_;
EntityIterator sequentialIt_;
EntityIterator sequentialEnd_;
std::mutex mutex_;
};
} // namespace Opm
#endif