src/testutils/mpitest.h

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  35 /*! \libinternal \file
  36  * \brief
  37  * Helper functions for MPI tests to make thread-MPI look like real MPI.
  38  *
  39  * \author Teemu Murtola <teemu.murtola@gmail.com>
  40  * \inlibraryapi
  41  * \ingroup module_testutils
  42  */
  43 #ifndef GMX_TESTUTILS_MPITEST_H
  44 #define GMX_TESTUTILS_MPITEST_H
  45
  46 #include "config.h"
  47
  48 #include <functional>
  49 #include <type_traits>
  50
  51 #include "gromacs/utility/basenetwork.h"
  52
  53 namespace gmx
  54 {
  55 namespace test
  56 {
  57
  58 /*! \brief
  59  * Returns the number of MPI ranks to use for an MPI test.
  60  *
  61  * For thread-MPI builds, this will return the requested number of ranks
  62  * even before the thread-MPI threads have been started.
  63  *
  64  * \ingroup module_testutils
  65  */
  66 int getNumberOfTestMpiRanks();
  67 //! \cond internal
  68 /*! \brief
  69  * Helper function for GMX_MPI_TEST().
  70  *
  71  * \ingroup module_testutils
  72  */
  73 bool threadMpiTestRunner(std::function<void()> testBody);
  74 //! \endcond
  75
  76 /*! \brief
  77  * Declares that this test is an MPI-enabled unit test.
  78  *
  79  * \param[in] expectedRankCount Expected number of ranks for this test.
  80  *     The test will fail if run with unsupported number of ranks.
  81  *
  82  * To write unit tests that run under MPI, you need to do a few things:
  83  *  - Put GMX_MPI_TEST() as the first statement in your test body and
  84  *    specify the number of ranks this test expects.
  85  *  - Declare your unit test in CMake with gmx_add_mpi_unit_test().
  86  *    Note that all tests in the binary should fulfill the conditions above,
  87  *    and work with the same number of ranks.
  88  * TODO: Figure out a mechanism for mixing tests with different rank counts in
  89  * the same binary (possibly, also MPI and non-MPI tests).
  90  *
  91  * When you do the above, the following will happen:
  92  *  - The test will get compiled only if thread-MPI or real MPI is enabled.
  93  *  - The test will get executed on the number of ranks specified.
  94  *    If you are using real MPI, the whole test binary is run under MPI and
  95  *    test execution across the processes is synchronized (GMX_MPI_TEST()
  96  *    actually has no effect in this case, the synchronization is handled at a
  97  *    higher level).
  98  *    If you are using thread-MPI, GMX_MPI_TEST() is required and it
  99  *    initializes thread-MPI with the specified number of threads and runs the
 100  *    rest of the test on each of the threads.
 101  *
 102  * You need to be extra careful for variables in the test fixture, if you use
 103  * one: when run under thread-MPI, these will be shared across all the ranks,
 104  * while under real MPI, these are naturally different for each process.
 105  * Local variables in the test body are private to each rank in both cases.
 106  *
 107  * Currently, it is not possible to specify the number of ranks as one, because
 108  * that will lead to problems with (at least) thread-MPI, but such tests can be
 109  * written as serial tests anyways.
 110  *
 111  * \ingroup module_testutils
 112  */
 113 #if GMX_THREAD_MPI
 114 #define GMX_MPI_TEST(expectedRankCount) \
 115     do { \
 116         ASSERT_EQ(expectedRankCount, ::gmx::test::getNumberOfTestMpiRanks()); \
 117         using MyTestClass = std::remove_reference_t<decltype(*this)>; \
 118         if (!::gmx::test::threadMpiTestRunner(std::bind(&MyTestClass::TestBody, this))) \
 119         { \
 120             return; \
 121         } \
 122     } while (0)
 123 #else
 124 #define GMX_MPI_TEST(expectedRankCount) \
 125     ASSERT_EQ(expectedRankCount, ::gmx::test::getNumberOfTestMpiRanks())
 126 #endif
 127
 128 } // namespace test
 129 } // namespace gmx
 130
 131 #endif