boost/mpi/operations.hpp

   1 // Copyright (C) 2004 The Trustees of Indiana University.
   2 // Copyright (C) 2005-2006 Douglas Gregor <doug.gregor -at- gmail.com>
   3
   4 // Use, modification and distribution is subject to the Boost Software
   5 // License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
   6 // http://www.boost.org/LICENSE_1_0.txt)
   7
   8 //  Authors: Douglas Gregor
   9 //           Andrew Lumsdaine
  10
  11 /** @file operations.hpp
  12  *
  13  *  This header provides a mapping from function objects to @c MPI_Op
  14  *  constants used in MPI collective operations. It also provides
  15  *  several new function object types not present in the standard @c
  16  *  <functional> header that have direct mappings to @c MPI_Op.
  17  */
  18 #ifndef BOOST_MPI_IS_MPI_OP_HPP
  19 #define BOOST_MPI_IS_MPI_OP_HPP
  20
  21 #include <boost/mpi/config.hpp>
  22 #include <boost/mpl/bool.hpp>
  23 #include <boost/mpl/if.hpp>
  24 #include <boost/mpl/and.hpp>
  25 #include <boost/mpi/datatype.hpp>
  26 #include <boost/utility/enable_if.hpp>
  27 #include <functional>
  28
  29 namespace boost { namespace mpi {
  30
  31 template<typename Op, typename T> struct is_mpi_op;
  32
  33 /**
  34  * @brief Determine if a function object type is commutative.
  35  *
  36  * This trait determines if an operation @c Op is commutative when
  37  * applied to values of type @c T. Parallel operations such as @c
  38  * reduce and @c prefix_sum can be implemented more efficiently with
  39  * commutative operations. To mark an operation as commutative, users
  40  * should specialize @c is_commutative and derive from the class @c
  41  * mpl::true_.
  42  */
  43 template<typename Op, typename T>
  44 struct is_commutative : public mpl::false_ { };
  45
  46 /**************************************************************************
  47  * Function objects for MPI operations not in <functional> header         *
  48  **************************************************************************/
  49
  50 /**
  51  *  @brief Compute the maximum of two values.
  52  *
  53  *  This binary function object computes the maximum of the two values
  54  *  it is given. When used with MPI and a type @c T that has an
  55  *  associated, built-in MPI data type, translates to @c MPI_MAX.
  56  */
  57 template<typename T>
  58 struct maximum : public std::binary_function<T, T, T>
  59 {
  60   /** @returns the maximum of x and y. */
  61   const T& operator()(const T& x, const T& y) const
  62   {
  63     return x < y? y : x;
  64   }
  65 };
  66
  67 /**
  68  *  @brief Compute the minimum of two values.
  69  *
  70  *  This binary function object computes the minimum of the two values
  71  *  it is given. When used with MPI and a type @c T that has an
  72  *  associated, built-in MPI data type, translates to @c MPI_MIN.
  73  */
  74 template<typename T>
  75 struct minimum : public std::binary_function<T, T, T>
  76 {
  77   /** @returns the minimum of x and y. */
  78   const T& operator()(const T& x, const T& y) const
  79   {
  80     return x < y? x : y;
  81   }
  82 };
  83
  84
  85 /**
  86  *  @brief Compute the bitwise AND of two integral values.
  87  *
  88  *  This binary function object computes the bitwise AND of the two
  89  *  values it is given. When used with MPI and a type @c T that has an
  90  *  associated, built-in MPI data type, translates to @c MPI_BAND.
  91  */
  92 template<typename T>
  93 struct bitwise_and : public std::binary_function<T, T, T>
  94 {
  95   /** @returns @c x & y. */
  96   T operator()(const T& x, const T& y) const
  97   {
  98     return x & y;
  99   }
 100 };
 101
 102 /**
 103  *  @brief Compute the bitwise OR of two integral values.
 104  *
 105  *  This binary function object computes the bitwise OR of the two
 106  *  values it is given. When used with MPI and a type @c T that has an
 107  *  associated, built-in MPI data type, translates to @c MPI_BOR.
 108  */
 109 template<typename T>
 110 struct bitwise_or : public std::binary_function<T, T, T>
 111 {
 112   /** @returns the @c x | y. */
 113   T operator()(const T& x, const T& y) const
 114   {
 115     return x | y;
 116   }
 117 };
 118
 119 /**
 120  *  @brief Compute the logical exclusive OR of two integral values.
 121  *
 122  *  This binary function object computes the logical exclusive of the
 123  *  two values it is given. When used with MPI and a type @c T that has
 124  *  an associated, built-in MPI data type, translates to @c MPI_LXOR.
 125  */
 126 template<typename T>
 127 struct logical_xor : public std::binary_function<T, T, T>
 128 {
 129   /** @returns the logical exclusive OR of x and y. */
 130   T operator()(const T& x, const T& y) const
 131   {
 132     return (x || y) && !(x && y);
 133   }
 134 };
 135
 136 /**
 137  *  @brief Compute the bitwise exclusive OR of two integral values.
 138  *
 139  *  This binary function object computes the bitwise exclusive OR of
 140  *  the two values it is given. When used with MPI and a type @c T that
 141  *  has an associated, built-in MPI data type, translates to @c
 142  *  MPI_BXOR.
 143  */
 144 template<typename T>
 145 struct bitwise_xor : public std::binary_function<T, T, T>
 146 {
 147   /** @returns @c x ^ y. */
 148   T operator()(const T& x, const T& y) const
 149   {
 150     return x ^ y;
 151   }
 152 };
 153
 154 /**************************************************************************
 155  * MPI_Op queries                                                         *
 156  **************************************************************************/
 157
 158 /**
 159  *  @brief Determine if a function object has an associated @c MPI_Op.
 160  *
 161  *  This trait determines if a function object type @c Op, when used
 162  *  with argument type @c T, has an associated @c MPI_Op. If so, @c
 163  *  is_mpi_op<Op,T> will derive from @c mpl::false_ and will
 164  *  contain a static member function @c op that takes no arguments but
 165  *  returns the associated @c MPI_Op value. For instance, @c
 166  *  is_mpi_op<std::plus<int>,int>::op() returns @c MPI_SUM.
 167  *
 168  *  Users may specialize @c is_mpi_op for any other class templates
 169  *  that map onto operations that have @c MPI_Op equivalences, such as
 170  *  bitwise OR, logical and, or maximum. However, users are encouraged
 171  *  to use the standard function objects in the @c functional and @c
 172  *  boost/mpi/operations.hpp headers whenever possible. For
 173  *  function objects that are class templates with a single template
 174  *  parameter, it may be easier to specialize @c is_builtin_mpi_op.
 175  */
 176 template<typename Op, typename T>
 177 struct is_mpi_op : public mpl::false_ { };
 178
 179 /// INTERNAL ONLY
 180 template<typename T>
 181 struct is_mpi_op<maximum<T>, T>
 182   : public boost::mpl::or_<is_mpi_integer_datatype<T>,
 183                            is_mpi_floating_point_datatype<T> >
 184 {
 185   static MPI_Op op() { return MPI_MAX; }
 186 };
 187
 188 /// INTERNAL ONLY
 189 template<typename T>
 190 struct is_mpi_op<minimum<T>, T>
 191   : public boost::mpl::or_<is_mpi_integer_datatype<T>,
 192                            is_mpi_floating_point_datatype<T> >
 193 {
 194   static MPI_Op op() { return MPI_MIN; }
 195 };
 196
 197 /// INTERNAL ONLY
 198 template<typename T>
 199  struct is_mpi_op<std::plus<T>, T>
 200   : public boost::mpl::or_<is_mpi_integer_datatype<T>,
 201                            is_mpi_floating_point_datatype<T>,
 202                            is_mpi_complex_datatype<T> >
 203 {
 204   static MPI_Op op() { return MPI_SUM; }
 205 };
 206
 207 /// INTERNAL ONLY
 208 template<typename T>
 209  struct is_mpi_op<std::multiplies<T>, T>
 210   : public boost::mpl::or_<is_mpi_integer_datatype<T>,
 211                            is_mpi_floating_point_datatype<T>,
 212                            is_mpi_complex_datatype<T> >
 213 {
 214   static MPI_Op op() { return MPI_PROD; }
 215 };
 216
 217 /// INTERNAL ONLY
 218 template<typename T>
 219  struct is_mpi_op<std::logical_and<T>, T>
 220   : public boost::mpl::or_<is_mpi_integer_datatype<T>,
 221                            is_mpi_logical_datatype<T> >
 222 {
 223   static MPI_Op op() { return MPI_LAND; }
 224 };
 225
 226 /// INTERNAL ONLY
 227 template<typename T>
 228  struct is_mpi_op<std::logical_or<T>, T>
 229   : public boost::mpl::or_<is_mpi_integer_datatype<T>,
 230                            is_mpi_logical_datatype<T> >
 231 {
 232   static MPI_Op op() { return MPI_LOR; }
 233 };
 234
 235 /// INTERNAL ONLY
 236 template<typename T>
 237  struct is_mpi_op<logical_xor<T>, T>
 238   : public boost::mpl::or_<is_mpi_integer_datatype<T>,
 239                            is_mpi_logical_datatype<T> >
 240 {
 241   static MPI_Op op() { return MPI_LXOR; }
 242 };
 243
 244 /// INTERNAL ONLY
 245 template<typename T>
 246  struct is_mpi_op<bitwise_and<T>, T>
 247   : public boost::mpl::or_<is_mpi_integer_datatype<T>,
 248                            is_mpi_byte_datatype<T> >
 249 {
 250   static MPI_Op op() { return MPI_BAND; }
 251 };
 252
 253 /// INTERNAL ONLY
 254 template<typename T>
 255  struct is_mpi_op<bitwise_or<T>, T>
 256   : public boost::mpl::or_<is_mpi_integer_datatype<T>,
 257                            is_mpi_byte_datatype<T> >
 258 {
 259   static MPI_Op op() { return MPI_BOR; }
 260 };
 261
 262 /// INTERNAL ONLY
 263 template<typename T>
 264  struct is_mpi_op<bitwise_xor<T>, T>
 265   : public boost::mpl::or_<is_mpi_integer_datatype<T>,
 266                            is_mpi_byte_datatype<T> >
 267 {
 268   static MPI_Op op() { return MPI_BXOR; }
 269 };
 270
 271 namespace detail {
 272   // A helper class used to create user-defined MPI_Ops
 273   template<typename Op, typename T>
 274   class user_op
 275   {
 276   public:
 277     explicit user_op(Op& op)
 278     {
 279       BOOST_MPI_CHECK_RESULT(MPI_Op_create,
 280                              (&user_op<Op, T>::perform,
 281                               is_commutative<Op, T>::value,
 282                               &mpi_op));
 283
 284       op_ptr = &op;
 285     }
 286
 287     ~user_op()
 288     {
 289       if (std::uncaught_exception()) {
 290         // Ignore failure cases: there are obviously other problems
 291         // already, and we don't want to cause program termination if
 292         // MPI_Op_free fails.
 293         MPI_Op_free(&mpi_op);
 294       } else {
 295         BOOST_MPI_CHECK_RESULT(MPI_Op_free, (&mpi_op));
 296       }
 297     }
 298
 299     MPI_Op& get_mpi_op()
 300     {
 301       return mpi_op;
 302     }
 303
 304   private:
 305     MPI_Op mpi_op;
 306     static Op* op_ptr;
 307
 308     static void BOOST_MPI_CALLING_CONVENTION perform(void* vinvec, void* voutvec, int* plen, MPI_Datatype*)
 309     {
 310       T* invec = static_cast<T*>(vinvec);
 311       T* outvec = static_cast<T*>(voutvec);
 312       std::transform(invec, invec + *plen, outvec, outvec, *op_ptr);
 313     }
 314   };
 315
 316   template<typename Op, typename T> Op* user_op<Op, T>::op_ptr = 0;
 317
 318 } // end namespace detail
 319
 320 } } // end namespace boost::mpi
 321
 322 #endif // BOOST_MPI_GET_MPI_OP_HPP