test_mpi_kernels.c

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/**
 * @file test_mpi_kernels.c
 * @brief C unit tests for MPI collective helper routines.
 */
 
#include "test_support.h"
 
#include "ParticleMotion.h"
#include "ParticleSwarm.h"
#include "grid.h"
 
#include <stdlib.h>
/**
 * @brief Tests collective particle distribution consistency across MPI ranks.
 */
 
static PetscErrorCode TestDistributeParticlesCollectiveConsistency(void)
{
    PetscMPIInt rank = 0, size = 1;
    PetscInt local_particles = 0;
    PetscInt remainder = 0;
    PetscInt global_particles = 0;
    PetscInt remainder_min = 0, remainder_max = 0;
    const PetscInt total_particles = 137;
 
    PetscFunctionBeginUser;
    PetscCallMPI(MPI_Comm_rank(PETSC_COMM_WORLD, &rank));
    PetscCallMPI(MPI_Comm_size(PETSC_COMM_WORLD, &size));
    PetscCall(PicurvAssertBool((PetscBool)(size >= 2), "unit-mpi requires at least two MPI ranks"));
 
    PetscCall(DistributeParticles(total_particles, rank, size, &local_particles, &remainder));
 
    PetscCall(PicurvAssertIntEqual(
        total_particles / size + (((PetscInt)rank < remainder) ? 1 : 0),
        local_particles,
        "local particle share should match quotient+remainder policy"));
 
    PetscCallMPI(MPI_Allreduce(&local_particles, &global_particles, 1, MPIU_INT, MPI_SUM, PETSC_COMM_WORLD));
    PetscCall(PicurvAssertIntEqual(total_particles, global_particles, "distributed particle count must conserve total particles"));
 
    PetscCallMPI(MPI_Allreduce(&remainder, &remainder_min, 1, MPIU_INT, MPI_MIN, PETSC_COMM_WORLD));
    PetscCallMPI(MPI_Allreduce(&remainder, &remainder_max, 1, MPIU_INT, MPI_MAX, PETSC_COMM_WORLD));
    PetscCall(PicurvAssertIntEqual(remainder_min, remainder_max, "all ranks should report the same remainder"));
    PetscFunctionReturn(0);
}
/**
 * @brief Tests multi-rank bounding-box gather and broadcast helpers.
 */
 
static PetscErrorCode TestBoundingBoxCollectivesMultiRank(void)
{
    SimCtx *simCtx = NULL;
    UserCtx *user = NULL;
    BoundingBox local_bbox;
    BoundingBox *boxes = NULL;
    PetscMPIInt rank = 0, size = 1;
    PetscReal global_min_x = 0.0;
    PetscReal global_max_x = 0.0;
    PetscReal expected_global_max_x = 0.0;
 
    PetscFunctionBeginUser;
    PetscCallMPI(MPI_Comm_rank(PETSC_COMM_WORLD, &rank));
    PetscCallMPI(MPI_Comm_size(PETSC_COMM_WORLD, &size));
    PetscCall(PicurvAssertBool((PetscBool)(size >= 2), "unit-mpi requires at least two MPI ranks"));
 
    PetscCall(PicurvCreateMinimalContexts(&simCtx, &user, 8, 6, 4));
    expected_global_max_x = ((PetscReal)(user->IM - 1) / (PetscReal)user->IM) + 1.0e-6;
    PetscCall(ComputeLocalBoundingBox(user, &local_bbox));
    PetscCall(GatherAllBoundingBoxes(user, &boxes));
    PetscCall(BroadcastAllBoundingBoxes(user, &boxes));
    PetscCall(PicurvAssertBool((PetscBool)(boxes != NULL), "all ranks should hold the gathered bounding-box table"));
 
    for (PetscMPIInt r = 0; r < size; ++r) {
        PetscCall(PicurvAssertBool((PetscBool)(boxes[r].min_coords.x <= boxes[r].max_coords.x), "bbox x-range should be valid"));
        PetscCall(PicurvAssertBool((PetscBool)(boxes[r].min_coords.y <= boxes[r].max_coords.y), "bbox y-range should be valid"));
        PetscCall(PicurvAssertBool((PetscBool)(boxes[r].min_coords.z <= boxes[r].max_coords.z), "bbox z-range should be valid"));
    }
 
    PetscCall(PicurvAssertRealNear(local_bbox.min_coords.x, boxes[rank].min_coords.x, 1.0e-10, "local bbox min x preserved"));
    PetscCall(PicurvAssertRealNear(local_bbox.max_coords.x, boxes[rank].max_coords.x, 1.0e-10, "local bbox max x preserved"));
 
    PetscCallMPI(MPI_Allreduce(&local_bbox.min_coords.x, &global_min_x, 1, MPIU_REAL, MPI_MIN, PETSC_COMM_WORLD));
    PetscCallMPI(MPI_Allreduce(&local_bbox.max_coords.x, &global_max_x, 1, MPIU_REAL, MPI_MAX, PETSC_COMM_WORLD));
    PetscCall(PicurvAssertBool((PetscBool)(global_min_x <= 0.0), "global min x should include domain start"));
    PetscCall(PicurvAssertRealNear(expected_global_max_x, global_max_x, 1.0e-10, "global max x should match the normalized physical-node domain end"));
 
    free(boxes);
    PetscCall(PicurvDestroyMinimalContexts(&simCtx, &user));
    PetscFunctionReturn(0);
}
/**
 * @brief Tests restart fast-path migration using preloaded cell ownership metadata.
 */
 
static PetscErrorCode TestRestartCellIdMigrationMovesParticleToOwner(void)
{
    SimCtx *simCtx = NULL;
    UserCtx *user = NULL;
    RankCellInfo my_cell_info;
    PetscMPIInt rank = 0, size = 1;
    PetscInt *cell_ids = NULL;
    PetscReal *positions = NULL;
    PetscInt nlocal = 0;
 
    PetscFunctionBeginUser;
    PetscCallMPI(MPI_Comm_rank(PETSC_COMM_WORLD, &rank));
    PetscCallMPI(MPI_Comm_size(PETSC_COMM_WORLD, &size));
    PetscCall(PicurvAssertIntEqual(2, size, "restart migration unit test expects exactly two MPI ranks"));
 
    PetscCall(PetscMemzero(&my_cell_info, sizeof(my_cell_info)));
    PetscCall(PicurvCreateMinimalContexts(&simCtx, &user, 8, 4, 4));
    PetscCall(PicurvCreateSwarmPair(user, 1, "ske"));
    PetscCall(GetOwnedCellRange(&user->info, 0, &my_cell_info.xs_cell, &my_cell_info.xm_cell));
    PetscCall(GetOwnedCellRange(&user->info, 1, &my_cell_info.ys_cell, &my_cell_info.ym_cell));
    PetscCall(GetOwnedCellRange(&user->info, 2, &my_cell_info.zs_cell, &my_cell_info.zm_cell));
    PetscCall(PetscMalloc1(size, &user->RankCellInfoMap));
    PetscCallMPI(MPI_Allgather(&my_cell_info, sizeof(RankCellInfo), MPI_BYTE,
                               user->RankCellInfoMap, sizeof(RankCellInfo), MPI_BYTE,
                               PETSC_COMM_WORLD));
 
    PetscCall(DMSwarmGetField(user->swarm, "DMSwarm_CellID", NULL, NULL, (void **)&cell_ids));
    PetscCall(DMSwarmGetField(user->swarm, "position", NULL, NULL, (void **)&positions));
    if (rank == 0) {
        cell_ids[0] = user->RankCellInfoMap[1].xs_cell;
        cell_ids[1] = user->RankCellInfoMap[1].ys_cell;
        cell_ids[2] = user->RankCellInfoMap[1].zs_cell;
        positions[0] = 0.875;
        positions[1] = 0.5;
        positions[2] = 0.5;
    } else {
        cell_ids[0] = user->RankCellInfoMap[1].xs_cell;
        cell_ids[1] = user->RankCellInfoMap[1].ys_cell;
        cell_ids[2] = user->RankCellInfoMap[1].zs_cell;
        positions[0] = 0.95;
        positions[1] = 0.5;
        positions[2] = 0.5;
    }
    PetscCall(DMSwarmRestoreField(user->swarm, "position", NULL, NULL, (void **)&positions));
    PetscCall(DMSwarmRestoreField(user->swarm, "DMSwarm_CellID", NULL, NULL, (void **)&cell_ids));
 
    PetscCall(MigrateRestartParticlesUsingCellID(user));
    PetscCall(DMSwarmGetLocalSize(user->swarm, &nlocal));
    PetscCall(PicurvAssertIntEqual((rank == 0) ? 0 : 2, nlocal,
                                   "restart migration should move the foreign particle onto the owning rank"));
 
    PetscCall(PicurvDestroyMinimalContexts(&simCtx, &user));
    PetscFunctionReturn(0);
}
/**
 * @brief Runs the unit-mpi PETSc test binary.
 */
 
int main(int argc, char **argv)
{
    PetscErrorCode ierr;
    const PicurvTestCase cases[] = {
        {"distribute-particles-collective-consistency", TestDistributeParticlesCollectiveConsistency},
        {"bounding-box-collectives-multi-rank", TestBoundingBoxCollectivesMultiRank},
        {"restart-cellid-migration-moves-particle-to-owner", TestRestartCellIdMigrationMovesParticleToOwner},
    };
 
    ierr = PetscInitialize(&argc, &argv, NULL, "PICurv MPI-focused runtime tests");
    if (ierr) {
        return (int)ierr;
    }
 
    ierr = PicurvRunTests("unit-mpi", cases, sizeof(cases) / sizeof(cases[0]));
    if (ierr) {
        PetscFinalize();
        return (int)ierr;
    }
 
    ierr = PetscFinalize();
    return (int)ierr;
}