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reduceAllInPlace.cpp
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41 
42 // Test that Teuchos::reduceAll allows aliasing input and output
43 // buffers, if the communicator is not an intercomm. Motivation:
44 // https://github.com/trilinos/Trilinos/issues/1389
45 
46 #include "Teuchos_DefaultComm.hpp"
47 #include "Teuchos_CommHelpers.hpp"
48 #ifdef HAVE_TEUCHOS_MPI
49 # include "mpi.h"
51 #endif // HAVE_TEUCHOS_MPI
53 
54 namespace { // (anonymous)
55 
56 #ifdef HAVE_TEUCHOS_MPI
57 MPI_Comm
58 getRawMpiCommFromTeuchosComm (const ::Teuchos::Comm<int>& comm)
59 {
60  using ::Teuchos::Comm;
61  using ::Teuchos::MpiComm;
62  using ::Teuchos::RCP;
63 
64  const Comm<int>* commPtr = &comm;
65  const MpiComm<int>* mpiCommPtr = dynamic_cast<const MpiComm<int>* > (commPtr);
66  if (mpiCommPtr == NULL) {
67  return MPI_COMM_SELF;
68  }
69  else {
70  using ::Teuchos::OpaqueWrapper;
71  using ::Teuchos::RCP;
72  RCP<const OpaqueWrapper<MPI_Comm> > wrapper = mpiCommPtr->getRawMpiComm ();
73  if (wrapper.is_null ()) {
74  return MPI_COMM_SELF;
75  }
76  else {
77  return *wrapper;
78  }
79  }
80 }
81 #endif // HAVE_TEUCHOS_MPI
82 
83 TEUCHOS_UNIT_TEST( Comm, ReduceAllInPlace )
84 {
85  using Teuchos::Comm;
86  using Teuchos::outArg;
87  using Teuchos::reduceAll;
88  using Teuchos::REDUCE_SUM;
89  using Teuchos::RCP;
90  using std::endl;
91 
92  out << "Test Teuchos::reduceAll with both intracomms and intercomms" << endl;
93  Teuchos::OSTab tab1 (out);
94 
95  RCP<const Comm<int> > comm = Teuchos::DefaultComm<int>::getComm ();
96  const int numProcs = comm->getSize ();
97  TEST_ASSERT( numProcs > 1 );
98  if (numProcs > 1) {
99  out << "This test requires > 1 processes in the input communicator "
100  "in order to be meaningful." << endl;
101  return;
102  }
103 
104  typedef int reduce_type; // type of reductions' input & output, for this test
105  reduce_type inputVal = 3;
106  reduce_type outputVal = 0; // output of reduceAll
107  const reduce_type expectedOutputVal = inputVal * numProcs;
108 
109  // Sanity check for reduceAll.
110  reduceAll<int, reduce_type> (*comm, REDUCE_SUM, inputVal, outArg (outputVal));
111  TEST_EQUALITY( outputVal, expectedOutputVal );
112 
113 #ifdef HAVE_TEUCHOS_MPI
114  MPI_Comm rawMpiComm = getRawMpiCommFromTeuchosComm (*comm);
115  int isInter = 0;
116  // This is a "local routine" (MPI 3.1, Section 6.6.1, p. 259).
117  (void) MPI_Comm_test_inter (rawMpiComm, &isInter);
118  if (isInter != 0) { // input communicator is an intercomm.
119  out << "Input communicator is an intercomm; "
120  "no point in continuing (not safe to exercise MPI_IN_PLACE)." << endl;
121  }
122  else { // input communicator is NOT an intercomm (is an intracomm)
123  out << "Input communicator is NOT an intercomm; "
124  "we may safely exercise MPI_IN_PLACE." << endl;
125 
126  // We hide use of MPI_IN_PLACE, by letting users alias the input
127  // and output buffers.
128  inputVal = 3;
129  reduceAll<int, reduce_type> (*comm, REDUCE_SUM, inputVal, outArg (inputVal));
130  TEST_EQUALITY( inputVal, expectedOutputVal );
131  }
132 
133  // Test whether we succeeded on all processes. This is particularly
134  // important when exercising MPI_IN_PLACE, since incorrect use of
135  // aliasing may cause only some processes to have incorrect results.
136  int lclSuccess = success ? 1 : 0;
137  int gblSuccess = 0; // output argument
138  const int err = MPI_Allreduce (&lclSuccess, &gblSuccess, 1, MPI_INT, MPI_MIN, rawMpiComm);
140  (err != MPI_SUCCESS, std::logic_error, "MPI_Allreduce failed!");
141  success = (gblSuccess == 1);
142  TEST_ASSERT( gblSuccess == 1 );
143 #endif // HAVE_TEUCHOS_MPI
144 }
145 
146 } // namespace (anonymous)
#define TEST_ASSERT(v1)
Assert the given statement is true.
#define TEUCHOS_TEST_FOR_EXCEPTION(throw_exception_test, Exception, msg)
Macro for throwing an exception with breakpointing to ease debugging.
#define TEST_EQUALITY(v1, v2)
Assert the equality of v1 and v2.
#define TEUCHOS_UNIT_TEST(TEST_GROUP, TEST_NAME)
Macro for defining a (non-templated) unit test.
static Teuchos::RCP< const Comm< OrdinalType > > getComm()
Return the default global communicator.
Tabbing class for helping to create formated, indented output for a basic_FancyOStream object...
Unit testing support.
Implementation of Teuchos wrappers for MPI.
Abstract interface for distributed-memory communication.
Smart reference counting pointer class for automatic garbage collection.
Ptr< T > outArg(T &arg)
create a non-persisting (required or optional) output argument for a function call.