NAME¶

disarray - distributed container (rheolef-7.2)

DESCRIPTION¶

This class provides a std::vector like container for a distributed memory model array.

The disarray interface is similar to those of the std::vector with the addition of some communication features for a distributed memory model.

EXAMPLE¶

    int main (int argc, char**argv) {


      environment distributed(argc, argv);


      distributor ownership (100);


      disarray<double> x (ownership, 3.14);


      dout << x << endl;


    }

NOTATION¶

There are two kind of indexes:

dis_i

i

Read and write accessors to the subset of the array that is owned by the current process are still denoted by square brackets, e.g. value = x[i] and x[i] = value, respectively.

Read and write accessors to the complete array, including array subsets that are owned by some others processors, are introduced with the help of new member functions:

x.dis_entry(dis_i) = value

value = x.dis_at(dis_i)

In order to optimize communications, they should be grouped.

GROUPED WRITES¶

Loop on any dis_i and write your value:

    for (...) { 


      x.dis_entry (dis_i) = value;


    }

Finally, perform all communications in one pass:

    x.dis_entry_assembly();

After this command, each value is stored in x, at its right place, depending on dis_i and its ownership. Note that, when dis_i is owned by the current process, the value is directly written as x[i] = value and no communication are generated.

GROUPED READS¶

First, define the set of indexes that you want to access:

    std::set<size_t> dis_i_set; 

Then, loop on dis_i all these indexes and append it to this set:

    for (...) {


      dis_i_set.insert (dis_i);


    }

Next, perform communications:

    x.set_dis_indexes (dis_i_set);

After this command, each values associated to the dis_i index, and that belongs to the index set, is also available also on the current processor:

    for (...) {


      value = x.dis_at (dis_i);


    }

Note that, when dis_i is owned by the current process, the value is directly read as value = x[i] and no communication are generated.

TEMPLATE PARAMETERS¶

Recall that the std::class that takes two template parameters, a T one for the stored elements and a A one for the memory allocator, the present disarray class take three template parameters:

• T: the stored object type
• M: the memory model, i.e. sequential or distributed, by default default_memory_model with is defined at the configuration stage
• A: the memory allocator, by default std::allocator

CONSTRUCTOR¶

In the sequential case, the class interface provides a simplified constructor:

    int local_size = 100;


    disarray<double,sequential> x (local_size, init_val);

This declaration is similar to those of a std::vector one: no communications are possible. In order to enable communication, your have to replace the local_size by information on how the array is distributed in memory:

      distributor ownership (100);


      disarray<double> x (ownership, 3.14);

The distributor(4) class does this job.

IMPLEMENTATION¶

This documentation has been generated from file linalg/lib/disarray.h

template <class T, class A>
class disarray<T,distributed,A> : public smart_pointer<disarray_rep<T,distributed,A> > {
public:
// typedefs:


    typedef disarray_rep<T,distributed,A> rep;


    typedef smart_pointer<rep>            base;


    typedef distributed                   memory_type;


    typedef typename rep::size_type       size_type;


    typedef typename rep::difference_type difference_type;


    typedef typename rep::value_type      value_type;


    typedef typename rep::reference       reference;


    typedef typename rep::dis_reference   dis_reference;


    typedef typename rep::iterator        iterator;


    typedef typename rep::const_reference const_reference;


    typedef typename rep::const_iterator  const_iterator;


    typedef typename rep::scatter_map_type scatter_map_type;
// allocators:


    disarray       (const distributor& ownership = distributor(), const T& init_val = T(), const A& alloc = A());


    void resize (const distributor& ownership = distributor(), const T& init_val = T());
// local accessors & modifiers:


    A get_allocator() const              { return base::data().get_allocator(); }


    size_type     size () const          { return base::data().size(); }


    size_type dis_size () const          { return base::data().dis_size(); }


    const distributor& ownership() const { return base::data().ownership(); }


    const communicator& comm() const     { return base::data().comm(); }


    reference       operator[] (size_type i)       { return base::data().operator[] (i); }


    const_reference operator[] (size_type i) const { return base::data().operator[] (i); }


    reference       operator() (size_type i)       { return base::data().operator[] (i); }


    const_reference operator() (size_type i) const { return base::data().operator[] (i); }


          iterator begin()       { return base::data().begin(); }


    const_iterator begin() const { return base::data().begin(); }


          iterator end()         { return base::data().end(); }


    const_iterator end() const   { return base::data().end(); }
// global accessor:


    template<class Set, class Map>


    void append_dis_entry (const Set& ext_idx_set, Map& ext_idx_map) const { base::data().append_dis_entry (ext_idx_set, ext_idx_map); }


    template<class Set, class Map>


    void get_dis_entry    (const Set& ext_idx_set, Map& ext_idx_map) const { base::data().get_dis_entry (ext_idx_set, ext_idx_map); }


    template<class Set>


    void append_dis_indexes (const Set& ext_idx_set) const { base::data().append_dis_indexes (ext_idx_set); }


    void reset_dis_indexes() const { base::data().reset_dis_indexes(); }


    void get_dis_indexes (std::set<size_type>& ext_idx_set) const { base::data().get_dis_indexes (ext_idx_set); }


    template<class Set>


    void set_dis_indexes    (const Set& ext_idx_set) const { base::data().set_dis_indexes (ext_idx_set); }


    const T& dis_at (size_type dis_i) const { return base::data().dis_at (dis_i); }


    // get all external pairs (dis_i, values):


    const scatter_map_type& get_dis_map_entries() const { return base::data().get_dis_map_entries(); }
// global modifiers (for compatibility with distributed interface):


    dis_reference dis_entry (size_type dis_i) { return base::data().dis_entry(dis_i); }


    template<class SetOp = typename details::default_set_op_traits<T>::type>


    void dis_entry_assembly_begin (SetOp my_set_op = SetOp()) { base::data().dis_entry_assembly_begin (my_set_op); }


    template<class SetOp = typename details::default_set_op_traits<T>::type>


    void dis_entry_assembly_end   (SetOp my_set_op = SetOp()) { base::data().dis_entry_assembly_end   (my_set_op); }


    template<class SetOp = typename details::default_set_op_traits<T>::type>


    void dis_entry_assembly       (SetOp my_set_op = SetOp()) { base::data().dis_entry_assembly       (my_set_op); }


    void dis_entry_assembly_begin() { base::data().template dis_entry_assembly_begin<typename details::default_set_op_traits<T>::type>(); }


    void dis_entry_assembly_end()   { base::data().template dis_entry_assembly_end<typename details::default_set_op_traits<T>::type>(); }


    void dis_entry_assembly()       { dis_entry_assembly_begin(); dis_entry_assembly_end(); }
// apply a partition:


 


    template<class RepSize>


    void repartition (                              // old_numbering for *this


        const RepSize&        partition,            // old_ownership


        disarray<T,distributed>& new_disarray,            // new_ownership (created)


        RepSize&              old_numbering,        // new_ownership


        RepSize&              new_numbering) const  // old_ownership


        { return base::data().repartition (partition.data(), new_disarray.data(), old_numbering.data(), new_numbering.data()); }


    template<class RepSize>


    void permutation_apply (                       // old_numbering for *this


        const RepSize&          new_numbering,     // old_ownership


        disarray<T,distributed,A>& new_disarray) const   // new_ownership (already allocated)


        { base::data().permutation_apply (new_numbering.data(), new_disarray.data()); }


    void reverse_permutation (                                 // old_ownership for *this=iold2dis_inew


        disarray<size_type,distributed,A>& inew2dis_iold) const   // new_ownership


        { base::data().reverse_permutation (inew2dis_iold.data()); }
// i/o:


    odiststream& put_values (odiststream& ops) const { return base::data().put_values(ops); }


    idiststream& get_values (idiststream& ips)       { return base::data().get_values(ips); }


    void dump (std::string name) const      { return base::data().dump(name); }


    template <class GetFunction>


    idiststream& get_values (idiststream& ips, GetFunction get_element)       { return base::data().get_values(ips, get_element); }


    template <class PutFunction>


    odiststream& put_values (odiststream& ops, PutFunction put_element) const { return base::data().put_values(ops, put_element); }


    template <class PutFunction, class A2> odiststream& permuted_put_values (


                odiststream& ops, const disarray<size_type,distributed,A2>& perm, PutFunction put_element) const 


                                                                     { return base::data().permuted_put_values (ops, perm.data(), put_element); }
};

AUTHOR¶

Pierre Saramito <Pierre.Saramito@imag.fr>

COPYRIGHT¶

Copyright (C) 2000-2018 Pierre Saramito <Pierre.Saramito@imag.fr> GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law.