// Copyright (C) 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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/** @file status.hpp
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*
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* This header defines the class @c status, which reports on the
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* results of point-to-point communication.
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*/
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#ifndef BOOST_MPI_STATUS_HPP
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#define BOOST_MPI_STATUS_HPP
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#include <boost/mpi/config.hpp>
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#include <boost/mpi/datatype.hpp>
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#include <boost/optional.hpp>
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#include <boost/mpl/bool.hpp>
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namespace boost { namespace mpi {
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class request;
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class communicator;
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/** @brief Contains information about a message that has been or can
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* be received.
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*
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* This structure contains status information about messages that
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* have been received (with @c communicator::recv) or can be received
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* (returned from @c communicator::probe or @c
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* communicator::iprobe). It permits access to the source of the
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* message, message tag, error code (rarely used), or the number of
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* elements that have been transmitted.
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*/
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class BOOST_MPI_DECL status
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{
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public:
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status() : m_count(-1) { }
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status(MPI_Status const& s) : m_status(s), m_count(-1) {}
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/**
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* Retrieve the source of the message.
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*/
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int source() const { return m_status.MPI_SOURCE; }
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/**
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* Retrieve the message tag.
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*/
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int tag() const { return m_status.MPI_TAG; }
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/**
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* Retrieve the error code.
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*/
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int error() const { return m_status.MPI_ERROR; }
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/**
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* Determine whether the communication associated with this object
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* has been successfully cancelled.
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*/
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bool cancelled() const;
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/**
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* Determines the number of elements of type @c T contained in the
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* message. The type @c T must have an associated data type, i.e.,
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* @c is_mpi_datatype<T> must derive @c mpl::true_. In cases where
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* the type @c T does not match the transmitted type, this routine
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* will return an empty @c optional<int>.
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*
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* @returns the number of @c T elements in the message, if it can be
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* determined.
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*/
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template<typename T> optional<int> count() const { return count_impl<T>(is_mpi_datatype<T>()); }
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/**
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* References the underlying @c MPI_Status
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*/
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operator MPI_Status&() { return m_status; }
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/**
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* References the underlying @c MPI_Status
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*/
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operator const MPI_Status&() const { return m_status; }
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private:
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/**
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* INTERNAL ONLY
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*/
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template<typename T> optional<int> count_impl(mpl::true_) const;
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/**
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* INTERNAL ONLY
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*/
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template<typename T> optional<int> count_impl(mpl::false_) const;
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public: // friend templates are not portable
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/// INTERNAL ONLY
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mutable MPI_Status m_status;
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mutable int m_count;
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friend class communicator;
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friend class request;
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};
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template<typename T>
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inline optional<int> status::count_impl(mpl::true_) const
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{
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if (m_count != -1)
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return m_count;
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int return_value;
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BOOST_MPI_CHECK_RESULT(MPI_Get_count,
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(&m_status, get_mpi_datatype<T>(T()), &return_value));
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if (return_value == MPI_UNDEFINED)
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return optional<int>();
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else
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/* Cache the result. */
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return m_count = return_value;
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}
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template<typename T>
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inline optional<int> status::count_impl(mpl::false_) const
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{
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if (m_count == -1)
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return optional<int>();
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else
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return m_count;
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}
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} } // end namespace boost::mpi
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#endif // BOOST_MPI_STATUS_HPP
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