parallel_for.h

/*
    Copyright 2005-2016 Intel Corporation.  All Rights Reserved.

    This file is part of Threading Building Blocks. Threading Building Blocks is free software;
    you can redistribute it and/or modify it under the terms of the GNU General Public License
    version 2  as  published  by  the  Free Software Foundation.  Threading Building Blocks 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 Threading Building Blocks; if not, write to the
    Free Software Foundation, Inc.,  51 Franklin St,  Fifth Floor,  Boston,  MA 02110-1301 USA

    As a special exception,  you may use this file  as part of a free software library without
    restriction.  Specifically,  if other files instantiate templates  or use macros or inline
    functions from this file, or you compile this file and link it with other files to produce
    an executable,  this file does not by itself cause the resulting executable to be covered
    by the GNU General Public License. This exception does not however invalidate any other
    reasons why the executable file might be covered by the GNU General Public License.
*/

#ifndef __TBB_parallel_for_H
#define __TBB_parallel_for_H

#include <new>
#include "task.h"
#include "partitioner.h"
#include "blocked_range.h"
#include "tbb_exception.h"

namespace tbb {

namespace interface9 {
namespace internal {

    void* allocate_sibling(task* start_for_task, size_t bytes);


    template<typename Range, typename Body, typename Partitioner>
    class start_for: public task {
        Range my_range;
        const Body my_body;
        typename Partitioner::task_partition_type my_partition;
        /*override*/ task* execute();

        /*override*/ void note_affinity( affinity_id id ) {
            my_partition.note_affinity( id );
        }

    public:
        start_for( const Range& range, const Body& body, Partitioner& partitioner ) :
            my_range(range),
            my_body(body),
            my_partition(partitioner)
        {
        }

        start_for( start_for& parent_, typename Partitioner::split_type& split_obj) :
            my_range(parent_.my_range, split_obj),
            my_body(parent_.my_body),
            my_partition(parent_.my_partition, split_obj)
        {
            my_partition.set_affinity(*this);
        }

        start_for( start_for& parent_, const Range& r, depth_t d ) :
            my_range(r),
            my_body(parent_.my_body),
            my_partition(parent_.my_partition, split())
        {
            my_partition.set_affinity(*this);
            my_partition.align_depth( d );
        }
        static void run(  const Range& range, const Body& body, Partitioner& partitioner ) {
            if( !range.empty() ) {
#if !__TBB_TASK_GROUP_CONTEXT || TBB_JOIN_OUTER_TASK_GROUP
                start_for& a = *new(task::allocate_root()) start_for(range,body,partitioner);
#else
                // Bound context prevents exceptions from body to affect nesting or sibling algorithms,
                // and allows users to handle exceptions safely by wrapping parallel_for in the try-block.
                task_group_context context;
                start_for& a = *new(task::allocate_root(context)) start_for(range,body,partitioner);
#endif /* __TBB_TASK_GROUP_CONTEXT && !TBB_JOIN_OUTER_TASK_GROUP */
                task::spawn_root_and_wait(a);
            }
        }
#if __TBB_TASK_GROUP_CONTEXT
        static void run(  const Range& range, const Body& body, Partitioner& partitioner, task_group_context& context ) {
            if( !range.empty() ) {
                start_for& a = *new(task::allocate_root(context)) start_for(range,body,partitioner);
                task::spawn_root_and_wait(a);
            }
        }
#endif /* __TBB_TASK_GROUP_CONTEXT */
        void run_body( Range &r ) { my_body( r ); }

        void offer_work(typename Partitioner::split_type& split_obj) {
            spawn( *new( allocate_sibling(static_cast<task*>(this), sizeof(start_for)) ) start_for(*this, split_obj) );
        }
        void offer_work(const Range& r, depth_t d = 0) {
            spawn( *new( allocate_sibling(static_cast<task*>(this), sizeof(start_for)) ) start_for(*this, r, d) );
        }
    };

    // TODO: 'inline' here is to avoid multiple definition error but for sake of code size this should not be inlined
    inline void* allocate_sibling(task* start_for_task, size_t bytes) {
        task* parent_ptr = new( start_for_task->allocate_continuation() ) flag_task();
        start_for_task->set_parent(parent_ptr);
        parent_ptr->set_ref_count(2);
        return &parent_ptr->allocate_child().allocate(bytes);
    }

    template<typename Range, typename Body, typename Partitioner>
    task* start_for<Range,Body,Partitioner>::execute() {
        my_partition.check_being_stolen( *this );
        my_partition.execute(*this, my_range);
        return NULL;
    }
} // namespace internal
} // namespace interfaceX

namespace internal {
    using interface9::internal::start_for;

    template<typename Function, typename Index>
    class parallel_for_body : internal::no_assign {
        const Function &my_func;
        const Index my_begin;
        const Index my_step;
    public:
        parallel_for_body( const Function& _func, Index& _begin, Index& _step )
            : my_func(_func), my_begin(_begin), my_step(_step) {}

        void operator()( const tbb::blocked_range<Index>& r ) const {
            // A set of local variables to help the compiler with vectorization of the following loop.
            Index b = r.begin();
            Index e = r.end();
            Index ms = my_step;
            Index k = my_begin + b*ms;

#if __INTEL_COMPILER
#pragma ivdep
#if __TBB_ASSERT_ON_VECTORIZATION_FAILURE
#pragma vector always assert
#endif
#endif
            for ( Index i = b; i < e; ++i, k += ms ) {
                my_func( k );
            }
        }
    };
} // namespace internal

// Requirements on Range concept are documented in blocked_range.h



template<typename Range, typename Body>
void parallel_for( const Range& range, const Body& body ) {
    internal::start_for<Range,Body,const __TBB_DEFAULT_PARTITIONER>::run(range,body,__TBB_DEFAULT_PARTITIONER());
}


template<typename Range, typename Body>
void parallel_for( const Range& range, const Body& body, const simple_partitioner& partitioner ) {
    internal::start_for<Range,Body,const simple_partitioner>::run(range,body,partitioner);
}


template<typename Range, typename Body>
void parallel_for( const Range& range, const Body& body, const auto_partitioner& partitioner ) {
    internal::start_for<Range,Body,const auto_partitioner>::run(range,body,partitioner);
}

#if TBB_PREVIEW_STATIC_PARTITIONER

template<typename Range, typename Body>
void parallel_for( const Range& range, const Body& body, const static_partitioner& partitioner ) {
    internal::start_for<Range,Body,const static_partitioner>::run(range,body,partitioner);
}
#endif


template<typename Range, typename Body>
void parallel_for( const Range& range, const Body& body, affinity_partitioner& partitioner ) {
    internal::start_for<Range,Body,affinity_partitioner>::run(range,body,partitioner);
}

#if __TBB_TASK_GROUP_CONTEXT

template<typename Range, typename Body>
void parallel_for( const Range& range, const Body& body, task_group_context& context ) {
    internal::start_for<Range,Body,const __TBB_DEFAULT_PARTITIONER>::run(range, body, __TBB_DEFAULT_PARTITIONER(), context);
}


template<typename Range, typename Body>
void parallel_for( const Range& range, const Body& body, const simple_partitioner& partitioner, task_group_context& context ) {
    internal::start_for<Range,Body,const simple_partitioner>::run(range, body, partitioner, context);
}


template<typename Range, typename Body>
void parallel_for( const Range& range, const Body& body, const auto_partitioner& partitioner, task_group_context& context ) {
    internal::start_for<Range,Body,const auto_partitioner>::run(range, body, partitioner, context);
}

#if TBB_PREVIEW_STATIC_PARTITIONER

template<typename Range, typename Body>
void parallel_for( const Range& range, const Body& body, const static_partitioner& partitioner, task_group_context& context ) {
    internal::start_for<Range,Body,const static_partitioner>::run(range, body, partitioner, context);
}
#endif


template<typename Range, typename Body>
void parallel_for( const Range& range, const Body& body, affinity_partitioner& partitioner, task_group_context& context ) {
    internal::start_for<Range,Body,affinity_partitioner>::run(range,body,partitioner, context);
}
#endif /* __TBB_TASK_GROUP_CONTEXT */


namespace strict_ppl {

template <typename Index, typename Function, typename Partitioner>
void parallel_for_impl(Index first, Index last, Index step, const Function& f, Partitioner& partitioner) {
    if (step <= 0 )
        internal::throw_exception(internal::eid_nonpositive_step); // throws std::invalid_argument
    else if (last > first) {
        // Above "else" avoids "potential divide by zero" warning on some platforms
        Index end = (last - first - Index(1)) / step + Index(1);
        tbb::blocked_range<Index> range(static_cast<Index>(0), end);
        internal::parallel_for_body<Function, Index> body(f, first, step);
        tbb::parallel_for(range, body, partitioner);
    }
}

template <typename Index, typename Function>
void parallel_for(Index first, Index last, Index step, const Function& f) {
    parallel_for_impl<Index,Function,const auto_partitioner>(first, last, step, f, auto_partitioner());
}
template <typename Index, typename Function>
void parallel_for(Index first, Index last, Index step, const Function& f, const simple_partitioner& partitioner) {
    parallel_for_impl<Index,Function,const simple_partitioner>(first, last, step, f, partitioner);
}
template <typename Index, typename Function>
void parallel_for(Index first, Index last, Index step, const Function& f, const auto_partitioner& partitioner) {
    parallel_for_impl<Index,Function,const auto_partitioner>(first, last, step, f, partitioner);
}
#if TBB_PREVIEW_STATIC_PARTITIONER
template <typename Index, typename Function>
void parallel_for(Index first, Index last, Index step, const Function& f, const static_partitioner& partitioner) {
    parallel_for_impl<Index,Function,const static_partitioner>(first, last, step, f, partitioner);
}
#endif
template <typename Index, typename Function>
void parallel_for(Index first, Index last, Index step, const Function& f, affinity_partitioner& partitioner) {
    parallel_for_impl(first, last, step, f, partitioner);
}

template <typename Index, typename Function>
void parallel_for(Index first, Index last, const Function& f) {
    parallel_for_impl<Index,Function,const auto_partitioner>(first, last, static_cast<Index>(1), f, auto_partitioner());
}
template <typename Index, typename Function>
void parallel_for(Index first, Index last, const Function& f, const simple_partitioner& partitioner) {
    parallel_for_impl<Index,Function,const simple_partitioner>(first, last, static_cast<Index>(1), f, partitioner);
}
template <typename Index, typename Function>
void parallel_for(Index first, Index last, const Function& f, const auto_partitioner& partitioner) {
    parallel_for_impl<Index,Function,const auto_partitioner>(first, last, static_cast<Index>(1), f, partitioner);
}
#if TBB_PREVIEW_STATIC_PARTITIONER
template <typename Index, typename Function>
void parallel_for(Index first, Index last, const Function& f, const static_partitioner& partitioner) {
    parallel_for_impl<Index,Function,const static_partitioner>(first, last, static_cast<Index>(1), f, partitioner);
}
#endif
template <typename Index, typename Function>
void parallel_for(Index first, Index last, const Function& f, affinity_partitioner& partitioner) {
    parallel_for_impl(first, last, static_cast<Index>(1), f, partitioner);
}

#if __TBB_TASK_GROUP_CONTEXT
template <typename Index, typename Function, typename Partitioner>
void parallel_for_impl(Index first, Index last, Index step, const Function& f, Partitioner& partitioner, tbb::task_group_context &context) {
    if (step <= 0 )
        internal::throw_exception(internal::eid_nonpositive_step); // throws std::invalid_argument
    else if (last > first) {
        // Above "else" avoids "potential divide by zero" warning on some platforms
        Index end = (last - first - Index(1)) / step + Index(1);
        tbb::blocked_range<Index> range(static_cast<Index>(0), end);
        internal::parallel_for_body<Function, Index> body(f, first, step);
        tbb::parallel_for(range, body, partitioner, context);
    }
}

template <typename Index, typename Function>
void parallel_for(Index first, Index last, Index step, const Function& f, tbb::task_group_context &context) {
    parallel_for_impl<Index,Function,const auto_partitioner>(first, last, step, f, auto_partitioner(), context);
}
 template <typename Index, typename Function>
void parallel_for(Index first, Index last, Index step, const Function& f, const simple_partitioner& partitioner, tbb::task_group_context &context) {
    parallel_for_impl<Index,Function,const simple_partitioner>(first, last, step, f, partitioner, context);
}
 template <typename Index, typename Function>
void parallel_for(Index first, Index last, Index step, const Function& f, const auto_partitioner& partitioner, tbb::task_group_context &context) {
    parallel_for_impl<Index,Function,const auto_partitioner>(first, last, step, f, partitioner, context);
}
#if TBB_PREVIEW_STATIC_PARTITIONER
template <typename Index, typename Function>
void parallel_for(Index first, Index last, Index step, const Function& f, const static_partitioner& partitioner, tbb::task_group_context &context) {
    parallel_for_impl<Index,Function,const static_partitioner>(first, last, step, f, partitioner, context);
}
#endif
 template <typename Index, typename Function>
void parallel_for(Index first, Index last, Index step, const Function& f, affinity_partitioner& partitioner, tbb::task_group_context &context) {
    parallel_for_impl(first, last, step, f, partitioner, context);
}


template <typename Index, typename Function>
void parallel_for(Index first, Index last, const Function& f, tbb::task_group_context &context) {
    parallel_for_impl<Index,Function,const auto_partitioner>(first, last, static_cast<Index>(1), f, auto_partitioner(), context);
}
 template <typename Index, typename Function>
void parallel_for(Index first, Index last, const Function& f, const simple_partitioner& partitioner, tbb::task_group_context &context) {
    parallel_for_impl<Index,Function,const simple_partitioner>(first, last, static_cast<Index>(1), f, partitioner, context);
}
 template <typename Index, typename Function>
void parallel_for(Index first, Index last, const Function& f, const auto_partitioner& partitioner, tbb::task_group_context &context) {
    parallel_for_impl<Index,Function,const auto_partitioner>(first, last, static_cast<Index>(1), f, partitioner, context);
}
#if TBB_PREVIEW_STATIC_PARTITIONER
template <typename Index, typename Function>
void parallel_for(Index first, Index last, const Function& f, const static_partitioner& partitioner, tbb::task_group_context &context) {
    parallel_for_impl<Index,Function,const static_partitioner>(first, last, static_cast<Index>(1), f, partitioner, context);
}
#endif
 template <typename Index, typename Function>
void parallel_for(Index first, Index last, const Function& f, affinity_partitioner& partitioner, tbb::task_group_context &context) {
    parallel_for_impl(first, last, static_cast<Index>(1), f, partitioner, context);
}

#endif /* __TBB_TASK_GROUP_CONTEXT */


} // namespace strict_ppl

using strict_ppl::parallel_for;

} // namespace tbb

#if TBB_PREVIEW_SERIAL_SUBSET
#define __TBB_NORMAL_EXECUTION
#include "../serial/tbb/parallel_for.h"
#undef __TBB_NORMAL_EXECUTION
#endif

#endif /* __TBB_parallel_for_H */