+/*
+ * This file is part of the GROMACS molecular simulation package.
+ *
+ * Copyright (c) 2021, by the GROMACS development team, led by
+ * Mark Abraham, David van der Spoel, Berk Hess, and Erik Lindahl,
+ * and including many others, as listed in the AUTHORS file in the
+ * top-level source directory and at http://www.gromacs.org.
+ *
+ * GROMACS is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public License
+ * as published by the Free Software Foundation; either version 2.1
+ * of the License, or (at your option) any later version.
+ *
+ * GROMACS is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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+ *
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+ * License along with GROMACS; if not, see
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+ */
+#include "gmxpre.h"
+
+#include "gromacs/applied_forces/awh/biassharing.h"
+
+#include <gmock/gmock.h>
+#include <gmock/gmock-matchers.h>
+#include <gtest/gtest.h>
+
+#include "gromacs/mdtypes/commrec.h"
+#include "thread_mpi/tmpi.h"
+
+#include "gromacs/applied_forces/awh/tests/awh_setup.h"
+#include "testutils/testasserts.h"
+
+namespace gmx
+{
+
+namespace test
+{
+
+// This test requires thread-MPI
+#if GMX_THREAD_MPI
+
+namespace
+{
+
+//! The number of thread-MPI ranks to run this test on
+const int c_numRanks = 4;
+
+//! The number of simulations sharing the same bias
+const int c_numSharingBiases = 2;
+
+/*! \brief The actual test body, executed by each MPI rank
+ *
+ * Sets ups sharing and sums over sahring simulations.
+ */
+void parallelTestFunction(const void gmx_unused* dummy)
+{
+ int numRanks;
+ MPI_Comm_size(MPI_COMM_WORLD, &numRanks);
+ GMX_RELEASE_ASSERT(numRanks == c_numRanks, "Expect c_numRanks thread-MPI ranks");
+
+ int myRank;
+ MPI_Comm_rank(MPI_COMM_WORLD, &myRank);
+ const int shareGroup = 1 + (myRank / c_numSharingBiases);
+
+ t_commrec commRecord;
+ commRecord.nnodes = 1;
+ commRecord.nodeid = 0;
+
+ const std::vector<char> serializedAwhParametersPerDim = awhDimParamSerialized();
+ auto awhDimArrayRef = gmx::arrayRefFromArray(&serializedAwhParametersPerDim, 1);
+ AwhTestParameters params = getAwhTestParameters(AwhHistogramGrowthType::ExponentialLinear,
+ AwhPotentialType::Convolved,
+ awhDimArrayRef,
+ false,
+ 0.4,
+ false,
+ 0.5,
+ 0,
+ shareGroup);
+
+ BiasSharing biasSharing(params.awhParams, commRecord, MPI_COMM_WORLD);
+
+ EXPECT_EQ(biasSharing.numSharingSimulations(0), c_numSharingBiases);
+ EXPECT_EQ(biasSharing.sharingSimulationIndex(0), myRank % c_numSharingBiases);
+
+ const std::array<int, c_numRanks> input{ 1, 2, 4, 8 };
+ std::array<int, 1> buffer{ input[myRank] };
+
+ biasSharing.sumOverMasterRanks(buffer, 0);
+ int expectedSum = 0;
+ for (int i = 0; i < c_numSharingBiases; i++)
+ {
+ expectedSum += input[(myRank / c_numSharingBiases) * c_numSharingBiases + i];
+ }
+ EXPECT_EQ(buffer[0], expectedSum);
+}
+
+} // namespace
+
+TEST(BiasSharingTest, SharingWorks)
+{
+ if (tMPI_Init_fn(TRUE, c_numRanks, TMPI_AFFINITY_NONE, parallelTestFunction, static_cast<const void*>(this))
+ != TMPI_SUCCESS)
+ {
+ GMX_THROW(gmx::InternalError("Failed to spawn thread-MPI threads"));
+ }
+}
+
+#endif
+
+} // namespace test
+} // namespace gmx