393 lines
13 KiB
C++
393 lines
13 KiB
C++
// (C) Copyright 2005 Matthias Troyer
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// (C) Copyright 2006 Douglas Gregor <doug.gregor -at gmail.com>
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// Use, modification and distribution is subject to the Boost Software
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// License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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// Authors: Matthias Troyer
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// Douglas Gregor
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/** @file skeleton_and_content.hpp
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*
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* This header provides facilities that allow the structure of data
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* types (called the "skeleton") to be transmitted and received
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* separately from the content stored in those data types. These
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* facilities are useful when the data in a stable data structure
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* (e.g., a mesh or a graph) will need to be transmitted
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* repeatedly. In this case, transmitting the skeleton only once
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* saves both communication effort (it need not be sent again) and
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* local computation (serialization need only be performed once for
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* the content).
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*/
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#ifndef BOOST_MPI_SKELETON_AND_CONTENT_HPP
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#define BOOST_MPI_SKELETON_AND_CONTENT_HPP
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#include <boost/mpi/config.hpp>
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#include <boost/archive/detail/auto_link_archive.hpp>
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#include <boost/mpi/packed_iarchive.hpp>
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#include <boost/mpi/packed_oarchive.hpp>
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#include <boost/mpi/detail/forward_skeleton_iarchive.hpp>
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#include <boost/mpi/detail/forward_skeleton_oarchive.hpp>
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#include <boost/mpi/detail/ignore_iprimitive.hpp>
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#include <boost/mpi/detail/ignore_oprimitive.hpp>
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#include <boost/shared_ptr.hpp>
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#include <boost/archive/detail/register_archive.hpp>
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namespace boost { namespace mpi {
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/**
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* @brief A proxy that requests that the skeleton of an object be
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* transmitted.
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*
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* The @c skeleton_proxy is a lightweight proxy object used to
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* indicate that the skeleton of an object, not the object itself,
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* should be transmitted. It can be used with the @c send and @c recv
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* operations of communicators or the @c broadcast collective. When a
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* @c skeleton_proxy is sent, Boost.MPI generates a description
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* containing the structure of the stored object. When that skeleton
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* is received, the receiving object is reshaped to match the
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* structure. Once the skeleton of an object as been transmitted, its
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* @c content can be transmitted separately (often several times)
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* without changing the structure of the object.
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*/
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template <class T>
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struct BOOST_MPI_DECL skeleton_proxy
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{
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/**
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* Constructs a @c skeleton_proxy that references object @p x.
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*
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* @param x the object whose structure will be transmitted or
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* altered.
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*/
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skeleton_proxy(T& x)
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: object(x)
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{}
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T& object;
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};
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/**
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* @brief Create a skeleton proxy object.
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*
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* This routine creates an instance of the skeleton_proxy class. It
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* will typically be used when calling @c send, @c recv, or @c
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* broadcast, to indicate that only the skeleton (structure) of an
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* object should be transmitted and not its contents.
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*
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* @param x the object whose structure will be transmitted.
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*
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* @returns a skeleton_proxy object referencing @p x
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*/
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template <class T>
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inline const skeleton_proxy<T> skeleton(T& x)
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{
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return skeleton_proxy<T>(x);
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}
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namespace detail {
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/// @brief a class holding an MPI datatype
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/// INTERNAL ONLY
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/// the type is freed upon destruction
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class BOOST_MPI_DECL mpi_datatype_holder : public boost::noncopyable
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{
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public:
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mpi_datatype_holder()
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: is_committed(false)
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{}
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mpi_datatype_holder(MPI_Datatype t, bool committed = true)
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: d(t)
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, is_committed(committed)
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{}
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void commit()
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{
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BOOST_MPI_CHECK_RESULT(MPI_Type_commit,(&d));
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is_committed=true;
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}
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MPI_Datatype get_mpi_datatype() const
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{
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return d;
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}
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~mpi_datatype_holder()
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{
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int finalized=0;
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BOOST_MPI_CHECK_RESULT(MPI_Finalized,(&finalized));
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if (!finalized && is_committed)
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BOOST_MPI_CHECK_RESULT(MPI_Type_free,(&d));
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}
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private:
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MPI_Datatype d;
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bool is_committed;
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};
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} // end namespace detail
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/** @brief A proxy object that transfers the content of an object
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* without its structure.
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*
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* The @c content class indicates that Boost.MPI should transmit or
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* receive the content of an object, but without any information
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* about the structure of the object. It is only meaningful to
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* transmit the content of an object after the receiver has already
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* received the skeleton for the same object.
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*
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* Most users will not use @c content objects directly. Rather, they
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* will invoke @c send, @c recv, or @c broadcast operations using @c
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* get_content().
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*/
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class BOOST_MPI_DECL content
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{
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public:
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/**
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* Constructs an empty @c content object. This object will not be
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* useful for any Boost.MPI operations until it is reassigned.
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*/
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content() {}
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/**
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* This routine initializes the @c content object with an MPI data
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* type that refers to the content of an object without its structure.
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*
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* @param d the MPI data type referring to the content of the object.
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*
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* @param committed @c true indicates that @c MPI_Type_commit has
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* already been excuted for the data type @p d.
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*/
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content(MPI_Datatype d, bool committed=true)
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: holder(new detail::mpi_datatype_holder(d,committed))
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{}
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/**
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* Replace the MPI data type referencing the content of an object.
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*
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* @param d the new MPI data type referring to the content of the
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* object.
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*
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* @returns *this
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*/
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const content& operator=(MPI_Datatype d)
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{
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holder.reset(new detail::mpi_datatype_holder(d));
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return *this;
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}
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/**
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* Retrieve the MPI data type that refers to the content of the
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* object.
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*
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* @returns the MPI data type, which should only be transmitted or
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* received using @c MPI_BOTTOM as the address.
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*/
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MPI_Datatype get_mpi_datatype() const
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{
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return holder->get_mpi_datatype();
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}
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/**
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* Commit the MPI data type referring to the content of the
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* object.
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*/
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void commit()
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{
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holder->commit();
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}
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private:
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boost::shared_ptr<detail::mpi_datatype_holder> holder;
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};
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/** @brief Returns the content of an object, suitable for transmission
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* via Boost.MPI.
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*
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* The function creates an absolute MPI datatype for the object,
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* where all offsets are counted from the address 0 (a.k.a. @c
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* MPI_BOTTOM) instead of the address @c &x of the object. This
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* allows the creation of MPI data types for complex data structures
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* containing pointers, such as linked lists or trees.
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*
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* The disadvantage, compared to relative MPI data types is that for
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* each object a new MPI data type has to be created.
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*
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* The contents of an object can only be transmitted when the
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* receiver already has an object with the same structure or shape as
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* the sender. To accomplish this, first transmit the skeleton of the
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* object using, e.g., @c skeleton() or @c skeleton_proxy.
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*
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* The type @c T has to allow creation of an absolute MPI data type
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* (content).
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*
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* @param x the object for which the content will be transmitted.
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*
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* @returns the content of the object @p x, which can be used for
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* transmission via @c send, @c recv, or @c broadcast.
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*/
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template <class T> const content get_content(const T& x);
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/** @brief An archiver that reconstructs a data structure based on the
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* binary skeleton stored in a buffer.
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*
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* The @c packed_skeleton_iarchive class is an Archiver (as in the
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* Boost.Serialization library) that can construct the the shape of a
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* data structure based on a binary skeleton stored in a buffer. The
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* @c packed_skeleton_iarchive is typically used by the receiver of a
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* skeleton, to prepare a data structure that will eventually receive
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* content separately.
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*
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* Users will not generally need to use @c packed_skeleton_iarchive
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* directly. Instead, use @c skeleton or @c get_skeleton.
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*/
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class BOOST_MPI_DECL packed_skeleton_iarchive
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: public detail::ignore_iprimitive,
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public detail::forward_skeleton_iarchive<packed_skeleton_iarchive,packed_iarchive>
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{
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public:
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/**
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* Construct a @c packed_skeleton_iarchive for the given
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* communicator.
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*
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* @param comm The communicator over which this archive will be
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* transmitted.
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*
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* @param flags Control the serialization of the skeleton. Refer to
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* the Boost.Serialization documentation before changing the
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* default flags.
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*/
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packed_skeleton_iarchive(MPI_Comm const & comm,
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unsigned int flags = boost::archive::no_header)
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: detail::forward_skeleton_iarchive<packed_skeleton_iarchive,packed_iarchive>(skeleton_archive_)
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, skeleton_archive_(comm,flags)
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{}
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/**
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* Construct a @c packed_skeleton_iarchive that unpacks a skeleton
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* from the given @p archive.
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*
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* @param archive the archive from which the skeleton will be
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* unpacked.
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*
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*/
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explicit packed_skeleton_iarchive(packed_iarchive & archive)
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: detail::forward_skeleton_iarchive<packed_skeleton_iarchive,packed_iarchive>(archive)
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, skeleton_archive_(MPI_COMM_WORLD, boost::archive::no_header)
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{}
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/**
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* Retrieve the archive corresponding to this skeleton.
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*/
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const packed_iarchive& get_skeleton() const
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{
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return this->implementation_archive;
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}
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/**
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* Retrieve the archive corresponding to this skeleton.
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*/
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packed_iarchive& get_skeleton()
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{
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return this->implementation_archive;
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}
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private:
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/// Store the actual archive that holds the structure, unless the
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/// user overrides this with their own archive.
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packed_iarchive skeleton_archive_;
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};
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/** @brief An archiver that records the binary skeleton of a data
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* structure into a buffer.
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*
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* The @c packed_skeleton_oarchive class is an Archiver (as in the
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* Boost.Serialization library) that can record the shape of a data
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* structure (called the "skeleton") into a binary representation
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* stored in a buffer. The @c packed_skeleton_oarchive is typically
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* used by the send of a skeleton, to pack the skeleton of a data
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* structure for transmission separately from the content.
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*
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* Users will not generally need to use @c packed_skeleton_oarchive
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* directly. Instead, use @c skeleton or @c get_skeleton.
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*/
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class BOOST_MPI_DECL packed_skeleton_oarchive
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: public detail::ignore_oprimitive,
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public detail::forward_skeleton_oarchive<packed_skeleton_oarchive,packed_oarchive>
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{
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public:
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/**
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* Construct a @c packed_skeleton_oarchive for the given
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* communicator.
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*
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* @param comm The communicator over which this archive will be
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* transmitted.
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*
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* @param flags Control the serialization of the skeleton. Refer to
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* the Boost.Serialization documentation before changing the
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* default flags.
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*/
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packed_skeleton_oarchive(MPI_Comm const & comm,
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unsigned int flags = boost::archive::no_header)
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: detail::forward_skeleton_oarchive<packed_skeleton_oarchive,packed_oarchive>(skeleton_archive_)
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, skeleton_archive_(comm,flags)
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{}
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/**
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* Construct a @c packed_skeleton_oarchive that packs a skeleton
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* into the given @p archive.
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*
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* @param archive the archive to which the skeleton will be packed.
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*
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*/
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explicit packed_skeleton_oarchive(packed_oarchive & archive)
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: detail::forward_skeleton_oarchive<packed_skeleton_oarchive,packed_oarchive>(archive)
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, skeleton_archive_(MPI_COMM_WORLD, boost::archive::no_header)
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{}
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/**
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* Retrieve the archive corresponding to this skeleton.
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*/
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const packed_oarchive& get_skeleton() const
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{
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return this->implementation_archive;
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}
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private:
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/// Store the actual archive that holds the structure.
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packed_oarchive skeleton_archive_;
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};
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namespace detail {
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typedef boost::mpi::detail::forward_skeleton_oarchive<boost::mpi::packed_skeleton_oarchive,boost::mpi::packed_oarchive> type1;
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typedef boost::mpi::detail::forward_skeleton_iarchive<boost::mpi::packed_skeleton_iarchive,boost::mpi::packed_iarchive> type2;
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}
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} } // end namespace boost::mpi
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#include <boost/mpi/detail/content_oarchive.hpp>
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// For any headers that have provided declarations based on forward
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// declarations of the contents of this header, include definitions
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// for those declarations. This means that the inclusion of
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// skeleton_and_content.hpp enables the use of skeleton/content
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// transmission throughout the library.
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#ifdef BOOST_MPI_BROADCAST_HPP
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# include <boost/mpi/detail/broadcast_sc.hpp>
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#endif
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#ifdef BOOST_MPI_COMMUNICATOR_HPP
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# include <boost/mpi/detail/communicator_sc.hpp>
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#endif
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// required by export
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BOOST_SERIALIZATION_REGISTER_ARCHIVE(boost::mpi::packed_skeleton_oarchive)
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BOOST_SERIALIZATION_REGISTER_ARCHIVE(boost::mpi::packed_skeleton_iarchive)
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BOOST_SERIALIZATION_REGISTER_ARCHIVE(boost::mpi::detail::type1)
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BOOST_SERIALIZATION_REGISTER_ARCHIVE(boost::mpi::detail::type2)
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BOOST_SERIALIZATION_USE_ARRAY_OPTIMIZATION(boost::mpi::packed_skeleton_oarchive)
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BOOST_SERIALIZATION_USE_ARRAY_OPTIMIZATION(boost::mpi::packed_skeleton_iarchive)
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#endif // BOOST_MPI_SKELETON_AND_CONTENT_HPP
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