1 // Copyright 2005 Douglas Gregor.
2
3 // Use, modification and distribution is subject to the Boost Software
4 // License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
5 // http://www.boost.org/LICENSE_1_0.txt)
6
7 // Message Passing Interface 1.1 -- Section 3. MPI Point-to-point
8
9 /* There is the potential for optimization here. We could keep around
10 a "small message" buffer of size N that we just receive into by
11 default. If the message is N - sizeof(int) bytes or smaller, it can
12 just be sent with that buffer. If it's larger, we send the first N
13 - sizeof(int) bytes in the first packet followed by another
14 packet. The size of the second packet will be stored in an integer
15 at the end of the first packet.
16
17 We will introduce this optimization later, when we have more
18 performance test cases and have met our functionality goals. */
19
20 #include <boost/mpi/detail/point_to_point.hpp>
21 #include <boost/mpi/datatype.hpp>
22 #include <boost/mpi/exception.hpp>
23 #include <boost/mpi/request.hpp>
24 #include <boost/mpi/communicator.hpp>
25 #include <boost/mpi/detail/antiques.hpp>
26 #include <cassert>
27
28 namespace boost { namespace mpi { namespace detail {
29
30 void
packed_archive_send(communicator const & comm,int dest,int tag,const packed_oarchive & ar)31 packed_archive_send(communicator const& comm, int dest, int tag,
32 const packed_oarchive& ar)
33 {
34 #if defined(BOOST_MPI_USE_IMPROBE)
35 {
36 void *buf = detail::unconst(ar.address());
37 BOOST_MPI_CHECK_RESULT(MPI_Send,
38 (buf, ar.size(), MPI_PACKED,
39 dest, tag, comm));
40 }
41 #else
42 {
43 std::size_t const& size = ar.size();
44 BOOST_MPI_CHECK_RESULT(MPI_Send,
45 (detail::unconst(&size), 1,
46 get_mpi_datatype(size),
47 dest, tag, comm));
48 BOOST_MPI_CHECK_RESULT(MPI_Send,
49 (detail::unconst(ar.address()), size,
50 MPI_PACKED,
51 dest, tag, comm));
52 }
53 #endif
54 }
55
56 request
packed_archive_isend(communicator const & comm,int dest,int tag,const packed_oarchive & ar)57 packed_archive_isend(communicator const& comm, int dest, int tag,
58 const packed_oarchive& ar)
59 {
60 return request::make_packed_send(comm, dest, tag,
61 detail::unconst(ar.address()), ar.size());
62 }
63
64 request
packed_archive_isend(communicator const & comm,int dest,int tag,const packed_iarchive & ar)65 packed_archive_isend(communicator const& comm, int dest, int tag,
66 const packed_iarchive& ar)
67 {
68 return request::make_packed_send(comm, dest, tag,
69 detail::unconst(ar.address()), ar.size());
70 }
71
72 void
packed_archive_recv(communicator const & comm,int source,int tag,packed_iarchive & ar,MPI_Status & status)73 packed_archive_recv(communicator const& comm, int source, int tag, packed_iarchive& ar,
74 MPI_Status& status)
75 {
76 #if defined(BOOST_MPI_USE_IMPROBE)
77 {
78 MPI_Message msg;
79 BOOST_MPI_CHECK_RESULT(MPI_Mprobe, (source, tag, comm, &msg, &status));
80 int count;
81 BOOST_MPI_CHECK_RESULT(MPI_Get_count, (&status, MPI_PACKED, &count));
82 ar.resize(count);
83 BOOST_MPI_CHECK_RESULT(MPI_Mrecv, (ar.address(), count, MPI_PACKED, &msg, &status));
84 }
85 #else
86 {
87 std::size_t count;
88 BOOST_MPI_CHECK_RESULT(MPI_Recv,
89 (&count, 1, get_mpi_datatype(count),
90 source, tag, comm, &status));
91
92 // Prepare input buffer and receive the message
93 ar.resize(count);
94 BOOST_MPI_CHECK_RESULT(MPI_Recv,
95 (ar.address(), count, MPI_PACKED,
96 status.MPI_SOURCE, status.MPI_TAG,
97 comm, &status));
98 }
99 #endif
100 }
101
102 } } } // end namespace boost::mpi::detail
103