/*
     Code for some of the parallel vector primitives.
*/
#include <../src/vec/vec/impls/mpi/pvecimpl.h> /*I  "petscvec.h"   I*/
#include <petsc/private/viewerhdf5impl.h>
#include <petsc/private/glvisviewerimpl.h>
#include <petsc/private/glvisvecimpl.h>
#include <petscsf.h>

static PetscErrorCode VecResetPreallocationCOO_MPI(Vec v)
{
  Vec_MPI *vmpi = (Vec_MPI *)v->data;

  PetscFunctionBegin;
  if (vmpi) {
    PetscCall(PetscFree(vmpi->jmap1));
    PetscCall(PetscFree(vmpi->perm1));
    PetscCall(PetscFree(vmpi->Cperm));
    PetscCall(PetscFree4(vmpi->imap2, vmpi->jmap2, vmpi->sendbuf, vmpi->recvbuf));
    PetscCall(PetscFree(vmpi->perm2));
    PetscCall(PetscSFDestroy(&vmpi->coo_sf));
  }
  PetscFunctionReturn(PETSC_SUCCESS);
}

PetscErrorCode VecDestroy_MPI(Vec v)
{
  Vec_MPI *x = (Vec_MPI *)v->data;

  PetscFunctionBegin;
  PetscCall(PetscLogObjectState((PetscObject)v, "Length=%" PetscInt_FMT, v->map->N));
  if (!x) PetscFunctionReturn(PETSC_SUCCESS);
  PetscCall(PetscFree(x->array_allocated));

  /* Destroy local representation of vector if it exists */
  if (x->localrep) {
    PetscCall(VecDestroy(&x->localrep));
    PetscCall(VecScatterDestroy(&x->localupdate));
    PetscCall(ISDestroy(&x->ghost));
  }
  PetscCall(VecAssemblyReset_MPI(v));

  /* Destroy the stashes: note the order - so that the tags are freed properly */
  PetscCall(VecStashDestroy_Private(&v->bstash));
  PetscCall(VecStashDestroy_Private(&v->stash));

  PetscCall(VecResetPreallocationCOO_MPI(v));
  PetscCall(PetscObjectComposeFunction((PetscObject)v, "PetscMatlabEnginePut_C", NULL));
  PetscCall(PetscObjectComposeFunction((PetscObject)v, "PetscMatlabEngineGet_C", NULL));
  PetscCall(PetscFree(v->data));
  PetscFunctionReturn(PETSC_SUCCESS);
}

static PetscErrorCode VecView_MPI_ASCII(Vec xin, PetscViewer viewer)
{
  PetscInt           i, work = xin->map->n, cnt, nLen;
  PetscMPIInt        j, n = 0, size, rank, tag = ((PetscObject)viewer)->tag, len;
  MPI_Status         status;
  PetscScalar       *values;
  const PetscScalar *xarray;
  const char        *name;
  PetscViewerFormat  format;

  PetscFunctionBegin;
  PetscCallMPI(MPI_Comm_size(PetscObjectComm((PetscObject)xin), &size));
  PetscCall(PetscViewerGetFormat(viewer, &format));
  if (format == PETSC_VIEWER_LOAD_BALANCE) {
    PetscInt nmax = 0, nmin = xin->map->n, navg;
    for (PetscMPIInt i = 0; i < size; i++) {
      nmax = PetscMax(nmax, xin->map->range[i + 1] - xin->map->range[i]);
      nmin = PetscMin(nmin, xin->map->range[i + 1] - xin->map->range[i]);
    }
    navg = xin->map->N / size;
    PetscCall(PetscViewerASCIIPrintf(viewer, "  Load Balance - Local vector size Min %" PetscInt_FMT "  avg %" PetscInt_FMT "  max %" PetscInt_FMT "\n", nmin, navg, nmax));
    PetscFunctionReturn(PETSC_SUCCESS);
  }

  PetscCall(VecGetArrayRead(xin, &xarray));
  /* determine maximum message to arrive */
  PetscCallMPI(MPI_Comm_rank(PetscObjectComm((PetscObject)xin), &rank));
  PetscCallMPI(MPI_Reduce(rank ? &work : MPI_IN_PLACE, &work, 1, MPIU_INT, MPI_MAX, 0, PetscObjectComm((PetscObject)xin)));
  PetscCall(PetscMPIIntCast(work, &len));
  if (format == PETSC_VIEWER_ASCII_GLVIS) rank = 0, len = 0; /* no parallel distributed write support from GLVis */
  if (rank == 0) {
    PetscCall(PetscMalloc1(len, &values));
    /*
        MATLAB format and ASCII format are very similar except
        MATLAB uses %18.16e format while ASCII uses %g
    */
    if (format == PETSC_VIEWER_ASCII_MATLAB) {
      PetscCall(PetscObjectGetName((PetscObject)xin, &name));
      PetscCall(PetscViewerASCIIPrintf(viewer, "%s = [\n", name));
      for (i = 0; i < xin->map->n; i++) {
#if defined(PETSC_USE_COMPLEX)
        if (PetscImaginaryPart(xarray[i]) > 0.0) {
          PetscCall(PetscViewerASCIIPrintf(viewer, "%18.16e + %18.16ei\n", (double)PetscRealPart(xarray[i]), (double)PetscImaginaryPart(xarray[i])));
        } else if (PetscImaginaryPart(xarray[i]) < 0.0) {
          PetscCall(PetscViewerASCIIPrintf(viewer, "%18.16e - %18.16ei\n", (double)PetscRealPart(xarray[i]), -(double)PetscImaginaryPart(xarray[i])));
        } else {
          PetscCall(PetscViewerASCIIPrintf(viewer, "%18.16e\n", (double)PetscRealPart(xarray[i])));
        }
#else
        PetscCall(PetscViewerASCIIPrintf(viewer, "%18.16e\n", (double)xarray[i]));
#endif
      }
      /* receive and print messages */
      for (j = 1; j < size; j++) {
        PetscCallMPI(MPI_Recv(values, len, MPIU_SCALAR, j, tag, PetscObjectComm((PetscObject)xin), &status));
        PetscCallMPI(MPI_Get_count(&status, MPIU_SCALAR, &n));
        for (i = 0; i < n; i++) {
#if defined(PETSC_USE_COMPLEX)
          if (PetscImaginaryPart(values[i]) > 0.0) {
            PetscCall(PetscViewerASCIIPrintf(viewer, "%18.16e + %18.16ei\n", (double)PetscRealPart(values[i]), (double)PetscImaginaryPart(values[i])));
          } else if (PetscImaginaryPart(values[i]) < 0.0) {
            PetscCall(PetscViewerASCIIPrintf(viewer, "%18.16e - %18.16ei\n", (double)PetscRealPart(values[i]), -(double)PetscImaginaryPart(values[i])));
          } else {
            PetscCall(PetscViewerASCIIPrintf(viewer, "%18.16e\n", (double)PetscRealPart(values[i])));
          }
#else
          PetscCall(PetscViewerASCIIPrintf(viewer, "%18.16e\n", (double)values[i]));
#endif
        }
      }
      PetscCall(PetscViewerASCIIPrintf(viewer, "];\n"));

    } else if (format == PETSC_VIEWER_ASCII_SYMMODU) {
      for (i = 0; i < xin->map->n; i++) {
#if defined(PETSC_USE_COMPLEX)
        PetscCall(PetscViewerASCIIPrintf(viewer, "%18.16e %18.16e\n", (double)PetscRealPart(xarray[i]), (double)PetscImaginaryPart(xarray[i])));
#else
        PetscCall(PetscViewerASCIIPrintf(viewer, "%18.16e\n", (double)xarray[i]));
#endif
      }
      /* receive and print messages */
      for (j = 1; j < size; j++) {
        PetscCallMPI(MPI_Recv(values, len, MPIU_SCALAR, j, tag, PetscObjectComm((PetscObject)xin), &status));
        PetscCallMPI(MPI_Get_count(&status, MPIU_SCALAR, &n));
        for (i = 0; i < n; i++) {
#if defined(PETSC_USE_COMPLEX)
          PetscCall(PetscViewerASCIIPrintf(viewer, "%18.16e %18.16e\n", (double)PetscRealPart(values[i]), (double)PetscImaginaryPart(values[i])));
#else
          PetscCall(PetscViewerASCIIPrintf(viewer, "%18.16e\n", (double)values[i]));
#endif
        }
      }
    } else if (format == PETSC_VIEWER_ASCII_PCICE) {
      PetscInt bs, b, vertexCount = 1;

      PetscCall(VecGetLocalSize(xin, &nLen));
      PetscCall(PetscMPIIntCast(nLen, &n));
      PetscCall(VecGetBlockSize(xin, &bs));
      PetscCheck(bs >= 1 && bs <= 3, PETSC_COMM_SELF, PETSC_ERR_ARG_WRONGSTATE, "PCICE can only handle up to 3D objects, but vector dimension is %" PetscInt_FMT, bs);

      PetscCall(PetscViewerASCIIPrintf(viewer, "%" PetscInt_FMT "\n", xin->map->N / bs));
      for (i = 0; i < n / bs; i++) {
        PetscCall(PetscViewerASCIIPrintf(viewer, "%7" PetscInt_FMT "   ", vertexCount++));
        for (b = 0; b < bs; b++) {
          if (b > 0) PetscCall(PetscViewerASCIIPrintf(viewer, " "));
#if !defined(PETSC_USE_COMPLEX)
          PetscCall(PetscViewerASCIIPrintf(viewer, "% 12.5E", (double)xarray[i * bs + b]));
#endif
        }
        PetscCall(PetscViewerASCIIPrintf(viewer, "\n"));
      }
      for (j = 1; j < size; j++) {
        PetscCallMPI(MPI_Recv(values, len, MPIU_SCALAR, j, tag, PetscObjectComm((PetscObject)xin), &status));
        PetscCallMPI(MPI_Get_count(&status, MPIU_SCALAR, &n));
        for (i = 0; i < n / bs; i++) {
          PetscCall(PetscViewerASCIIPrintf(viewer, "%7" PetscInt_FMT "   ", vertexCount++));
          for (b = 0; b < bs; b++) {
            if (b > 0) PetscCall(PetscViewerASCIIPrintf(viewer, " "));
#if !defined(PETSC_USE_COMPLEX)
            PetscCall(PetscViewerASCIIPrintf(viewer, "% 12.5E", (double)values[i * bs + b]));
#endif
          }
          PetscCall(PetscViewerASCIIPrintf(viewer, "\n"));
        }
      }
    } else if (format == PETSC_VIEWER_ASCII_GLVIS) {
      /* GLVis ASCII visualization/dump: this function mimics mfem::GridFunction::Save() */
      const PetscScalar      *array;
      PetscInt                i, n, vdim, ordering = 1; /* mfem::FiniteElementSpace::Ordering::byVDIM */
      PetscContainer          glvis_container;
      PetscViewerGLVisVecInfo glvis_vec_info;
      PetscViewerGLVisInfo    glvis_info;

      /* mfem::FiniteElementSpace::Save() */
      PetscCall(VecGetBlockSize(xin, &vdim));
      PetscCall(PetscViewerASCIIPrintf(viewer, "FiniteElementSpace\n"));
      PetscCall(PetscObjectQuery((PetscObject)xin, "_glvis_info_container", (PetscObject *)&glvis_container));
      PetscCheck(glvis_container, PetscObjectComm((PetscObject)xin), PETSC_ERR_PLIB, "Missing GLVis container");
      PetscCall(PetscContainerGetPointer(glvis_container, &glvis_vec_info));
      PetscCall(PetscViewerASCIIPrintf(viewer, "%s\n", glvis_vec_info->fec_type));
      PetscCall(PetscViewerASCIIPrintf(viewer, "VDim: %" PetscInt_FMT "\n", vdim));
      PetscCall(PetscViewerASCIIPrintf(viewer, "Ordering: %" PetscInt_FMT "\n", ordering));
      PetscCall(PetscViewerASCIIPrintf(viewer, "\n"));
      /* mfem::Vector::Print() */
      PetscCall(PetscObjectQuery((PetscObject)viewer, "_glvis_info_container", (PetscObject *)&glvis_container));
      PetscCheck(glvis_container, PetscObjectComm((PetscObject)viewer), PETSC_ERR_PLIB, "Missing GLVis container");
      PetscCall(PetscContainerGetPointer(glvis_container, &glvis_info));
      if (glvis_info->enabled) {
        PetscCall(VecGetLocalSize(xin, &n));
        PetscCall(VecGetArrayRead(xin, &array));
        for (i = 0; i < n; i++) {
          PetscCall(PetscViewerASCIIPrintf(viewer, glvis_info->fmt, (double)PetscRealPart(array[i])));
          PetscCall(PetscViewerASCIIPrintf(viewer, "\n"));
        }
        PetscCall(VecRestoreArrayRead(xin, &array));
      }
    } else if (format == PETSC_VIEWER_ASCII_INFO || format == PETSC_VIEWER_ASCII_INFO_DETAIL) {
      /* No info */
    } else {
      if (format != PETSC_VIEWER_ASCII_COMMON) PetscCall(PetscViewerASCIIPrintf(viewer, "Process [%d]\n", rank));
      cnt = 0;
      for (i = 0; i < xin->map->n; i++) {
        if (format == PETSC_VIEWER_ASCII_INDEX) PetscCall(PetscViewerASCIIPrintf(viewer, "%" PetscInt_FMT ": ", cnt++));
#if defined(PETSC_USE_COMPLEX)
        if (PetscImaginaryPart(xarray[i]) > 0.0) {
          PetscCall(PetscViewerASCIIPrintf(viewer, "%g + %g i\n", (double)PetscRealPart(xarray[i]), (double)PetscImaginaryPart(xarray[i])));
        } else if (PetscImaginaryPart(xarray[i]) < 0.0) {
          PetscCall(PetscViewerASCIIPrintf(viewer, "%g - %g i\n", (double)PetscRealPart(xarray[i]), -(double)PetscImaginaryPart(xarray[i])));
        } else {
          PetscCall(PetscViewerASCIIPrintf(viewer, "%g\n", (double)PetscRealPart(xarray[i])));
        }
#else
        PetscCall(PetscViewerASCIIPrintf(viewer, "%g\n", (double)xarray[i]));
#endif
      }
      /* receive and print messages */
      for (j = 1; j < size; j++) {
        PetscCallMPI(MPI_Recv(values, len, MPIU_SCALAR, j, tag, PetscObjectComm((PetscObject)xin), &status));
        PetscCallMPI(MPI_Get_count(&status, MPIU_SCALAR, &n));
        if (format != PETSC_VIEWER_ASCII_COMMON) PetscCall(PetscViewerASCIIPrintf(viewer, "Process [%d]\n", j));
        for (i = 0; i < n; i++) {
          if (format == PETSC_VIEWER_ASCII_INDEX) PetscCall(PetscViewerASCIIPrintf(viewer, "%" PetscInt_FMT ": ", cnt++));
#if defined(PETSC_USE_COMPLEX)
          if (PetscImaginaryPart(values[i]) > 0.0) {
            PetscCall(PetscViewerASCIIPrintf(viewer, "%g + %g i\n", (double)PetscRealPart(values[i]), (double)PetscImaginaryPart(values[i])));
          } else if (PetscImaginaryPart(values[i]) < 0.0) {
            PetscCall(PetscViewerASCIIPrintf(viewer, "%g - %g i\n", (double)PetscRealPart(values[i]), -(double)PetscImaginaryPart(values[i])));
          } else {
            PetscCall(PetscViewerASCIIPrintf(viewer, "%g\n", (double)PetscRealPart(values[i])));
          }
#else
          PetscCall(PetscViewerASCIIPrintf(viewer, "%g\n", (double)values[i]));
#endif
        }
      }
    }
    PetscCall(PetscFree(values));
  } else {
    if (format == PETSC_VIEWER_ASCII_INFO || format == PETSC_VIEWER_ASCII_INFO_DETAIL) {
      /* Rank 0 is not trying to receive anything, so don't send anything */
    } else {
      if (format == PETSC_VIEWER_ASCII_MATLAB) {
        /* this may be a collective operation so make sure everyone calls it */
        PetscCall(PetscObjectGetName((PetscObject)xin, &name));
      }
      PetscCallMPI(MPIU_Send((void *)xarray, xin->map->n, MPIU_SCALAR, 0, tag, PetscObjectComm((PetscObject)xin)));
    }
  }
  PetscCall(PetscViewerFlush(viewer));
  PetscCall(VecRestoreArrayRead(xin, &xarray));
  PetscFunctionReturn(PETSC_SUCCESS);
}

PetscErrorCode VecView_MPI_Binary(Vec xin, PetscViewer viewer)
{
  return VecView_Binary(xin, viewer);
}

#include <petscdraw.h>
PetscErrorCode VecView_MPI_Draw_LG(Vec xin, PetscViewer viewer)
{
  PetscDraw          draw;
  PetscBool          isnull;
  PetscDrawLG        lg;
  PetscMPIInt        i, size, rank, n, N, *lens = NULL, *disp = NULL;
  PetscReal         *values, *xx = NULL, *yy = NULL;
  const PetscScalar *xarray;
  int                colors[] = {PETSC_DRAW_RED};

  PetscFunctionBegin;
  PetscCall(PetscViewerDrawGetDraw(viewer, 0, &draw));
  PetscCall(PetscDrawIsNull(draw, &isnull));
  if (isnull) PetscFunctionReturn(PETSC_SUCCESS);
  PetscCallMPI(MPI_Comm_rank(PetscObjectComm((PetscObject)xin), &rank));
  PetscCallMPI(MPI_Comm_size(PetscObjectComm((PetscObject)xin), &size));
  PetscCall(PetscMPIIntCast(xin->map->n, &n));
  PetscCall(PetscMPIIntCast(xin->map->N, &N));

  PetscCall(VecGetArrayRead(xin, &xarray));
#if defined(PETSC_USE_COMPLEX)
  PetscCall(PetscMalloc1(n + 1, &values));
  for (i = 0; i < n; i++) values[i] = PetscRealPart(xarray[i]);
#else
  values = (PetscReal *)xarray;
#endif
  if (rank == 0) {
    PetscCall(PetscMalloc2(N, &xx, N, &yy));
    for (i = 0; i < N; i++) xx[i] = (PetscReal)i;
    PetscCall(PetscMalloc2(size, &lens, size, &disp));
    for (i = 0; i < size; i++) PetscCall(PetscMPIIntCast(xin->map->range[i + 1] - xin->map->range[i], &lens[i]));
    for (i = 0; i < size; i++) PetscCall(PetscMPIIntCast(xin->map->range[i], &disp[i]));
  }
  PetscCallMPI(MPI_Gatherv(values, n, MPIU_REAL, yy, lens, disp, MPIU_REAL, 0, PetscObjectComm((PetscObject)xin)));
  PetscCall(PetscFree2(lens, disp));
#if defined(PETSC_USE_COMPLEX)
  PetscCall(PetscFree(values));
#endif
  PetscCall(VecRestoreArrayRead(xin, &xarray));

  PetscCall(PetscViewerDrawGetDrawLG(viewer, 0, &lg));
  PetscCall(PetscDrawLGReset(lg));
  PetscCall(PetscDrawLGSetDimension(lg, 1));
  PetscCall(PetscDrawLGSetColors(lg, colors));
  if (rank == 0) {
    PetscCall(PetscDrawLGAddPoints(lg, N, &xx, &yy));
    PetscCall(PetscFree2(xx, yy));
  }
  PetscCall(PetscDrawLGDraw(lg));
  PetscCall(PetscDrawLGSave(lg));
  PetscFunctionReturn(PETSC_SUCCESS);
}

PETSC_INTERN PetscErrorCode VecView_MPI_Draw(Vec xin, PetscViewer viewer)
{
  PetscMPIInt        rank, size, tag = ((PetscObject)viewer)->tag;
  PetscInt           i, start, end;
  MPI_Status         status;
  PetscReal          min, max, tmp = 0.0;
  PetscDraw          draw;
  PetscBool          isnull;
  PetscDrawAxis      axis;
  const PetscScalar *xarray;

  PetscFunctionBegin;
  PetscCall(PetscViewerDrawGetDraw(viewer, 0, &draw));
  PetscCall(PetscDrawIsNull(draw, &isnull));
  if (isnull) PetscFunctionReturn(PETSC_SUCCESS);
  PetscCallMPI(MPI_Comm_size(PetscObjectComm((PetscObject)xin), &size));
  PetscCallMPI(MPI_Comm_rank(PetscObjectComm((PetscObject)xin), &rank));

  PetscCall(VecMin(xin, NULL, &min));
  PetscCall(VecMax(xin, NULL, &max));
  if (min == max) {
    min -= 1.e-5;
    max += 1.e-5;
  }

  PetscCall(PetscDrawCheckResizedWindow(draw));
  PetscCall(PetscDrawClear(draw));

  PetscCall(PetscDrawAxisCreate(draw, &axis));
  PetscCall(PetscDrawAxisSetLimits(axis, 0.0, (PetscReal)xin->map->N, min, max));
  PetscCall(PetscDrawAxisDraw(axis));
  PetscCall(PetscDrawAxisDestroy(&axis));

  /* draw local part of vector */
  PetscCall(VecGetArrayRead(xin, &xarray));
  PetscCall(VecGetOwnershipRange(xin, &start, &end));
  if (rank < size - 1) { /* send value to right */
    PetscCallMPI(MPI_Send((void *)&xarray[xin->map->n - 1], 1, MPIU_REAL, rank + 1, tag, PetscObjectComm((PetscObject)xin)));
  }
  if (rank) { /* receive value from right */
    PetscCallMPI(MPI_Recv(&tmp, 1, MPIU_REAL, rank - 1, tag, PetscObjectComm((PetscObject)xin), &status));
  }
  PetscDrawCollectiveBegin(draw);
  if (rank) PetscCall(PetscDrawLine(draw, (PetscReal)start - 1, tmp, (PetscReal)start, PetscRealPart(xarray[0]), PETSC_DRAW_RED));
  for (i = 1; i < xin->map->n; i++) PetscCall(PetscDrawLine(draw, (PetscReal)(i - 1 + start), PetscRealPart(xarray[i - 1]), (PetscReal)(i + start), PetscRealPart(xarray[i]), PETSC_DRAW_RED));
  PetscDrawCollectiveEnd(draw);
  PetscCall(VecRestoreArrayRead(xin, &xarray));

  PetscCall(PetscDrawFlush(draw));
  PetscCall(PetscDrawPause(draw));
  PetscCall(PetscDrawSave(draw));
  PetscFunctionReturn(PETSC_SUCCESS);
}

#if defined(PETSC_HAVE_MATLAB)
PetscErrorCode VecView_MPI_Matlab(Vec xin, PetscViewer viewer)
{
  PetscMPIInt        rank, size, *lens;
  PetscInt           i, N = xin->map->N;
  const PetscScalar *xarray;
  PetscScalar       *xx;

  PetscFunctionBegin;
  PetscCall(VecGetArrayRead(xin, &xarray));
  PetscCallMPI(MPI_Comm_rank(PetscObjectComm((PetscObject)xin), &rank));
  PetscCallMPI(MPI_Comm_size(PetscObjectComm((PetscObject)xin), &size));
  if (rank == 0) {
    PetscCall(PetscMalloc1(N, &xx));
    PetscCall(PetscMalloc1(size, &lens));
    for (i = 0; i < size; i++) lens[i] = xin->map->range[i + 1] - xin->map->range[i];

    PetscCallMPI(MPI_Gatherv((void *)xarray, xin->map->n, MPIU_SCALAR, xx, lens, xin->map->range, MPIU_SCALAR, 0, PetscObjectComm((PetscObject)xin)));
    PetscCall(PetscFree(lens));

    PetscCall(PetscObjectName((PetscObject)xin));
    PetscCall(PetscViewerMatlabPutArray(viewer, N, 1, xx, ((PetscObject)xin)->name));

    PetscCall(PetscFree(xx));
  } else {
    PetscCallMPI(MPI_Gatherv((void *)xarray, xin->map->n, MPIU_SCALAR, 0, 0, 0, MPIU_SCALAR, 0, PetscObjectComm((PetscObject)xin)));
  }
  PetscCall(VecRestoreArrayRead(xin, &xarray));
  PetscFunctionReturn(PETSC_SUCCESS);
}
#endif

#if defined(PETSC_HAVE_ADIOS)
  #include <adios.h>
  #include <adios_read.h>
  #include <petsc/private/vieweradiosimpl.h>
  #include <petsc/private/viewerimpl.h>

PetscErrorCode VecView_MPI_ADIOS(Vec xin, PetscViewer viewer)
{
  PetscViewer_ADIOS *adios = (PetscViewer_ADIOS *)viewer->data;
  const char        *vecname;
  int64_t            id;
  PetscInt           n, N, rstart;
  const PetscScalar *array;
  char               nglobalname[16], nlocalname[16], coffset[16];

  PetscFunctionBegin;
  PetscCall(PetscObjectGetName((PetscObject)xin, &vecname));

  PetscCall(VecGetLocalSize(xin, &n));
  PetscCall(VecGetSize(xin, &N));
  PetscCall(VecGetOwnershipRange(xin, &rstart, NULL));

  PetscCall(PetscSNPrintf(nlocalname, PETSC_STATIC_ARRAY_LENGTH(nlocalname), "%" PetscInt_FMT, n));
  PetscCall(PetscSNPrintf(nglobalname, PETSC_STATIC_ARRAY_LENGTH(nglobalname), "%" PetscInt_FMT, N));
  PetscCall(PetscSNPrintf(coffset, PETSC_STATIC_ARRAY_LENGTH(coffset), "%" PetscInt_FMT, rstart));
  id = adios_define_var(Petsc_adios_group, vecname, "", adios_double, nlocalname, nglobalname, coffset);
  PetscCall(VecGetArrayRead(xin, &array));
  PetscCallExternal(adios_write_byid, adios->adios_handle, id, array);
  PetscCall(VecRestoreArrayRead(xin, &array));
  PetscFunctionReturn(PETSC_SUCCESS);
}
#endif

#if defined(PETSC_HAVE_HDF5)
PetscErrorCode VecView_MPI_HDF5(Vec xin, PetscViewer viewer)
{
  PetscViewer_HDF5 *hdf5 = (PetscViewer_HDF5 *)viewer->data;
  /* TODO: It looks like we can remove the H5Sclose(filespace) and H5Dget_space(dset_id). Why do we do this? */
  hid_t              filespace;  /* file dataspace identifier */
  hid_t              chunkspace; /* chunk dataset property identifier */
  hid_t              dset_id;    /* dataset identifier */
  hid_t              memspace;   /* memory dataspace identifier */
  hid_t              file_id;
  hid_t              group;
  hid_t              memscalartype;  /* scalar type for mem (H5T_NATIVE_FLOAT or H5T_NATIVE_DOUBLE) */
  hid_t              filescalartype; /* scalar type for file (H5T_NATIVE_FLOAT or H5T_NATIVE_DOUBLE) */
  PetscInt           bs = xin->map->bs;
  hsize_t            dim;
  hsize_t            maxDims[4], dims[4], chunkDims[4], count[4], offset[4];
  PetscBool          timestepping, dim2, spoutput;
  PetscInt           timestep = PETSC_INT_MIN, low;
  hsize_t            chunksize;
  const PetscScalar *x;
  const char        *vecname;
  size_t             len;

  PetscFunctionBegin;
  PetscCall(PetscViewerHDF5OpenGroup(viewer, NULL, &file_id, &group));
  PetscCall(PetscViewerHDF5IsTimestepping(viewer, &timestepping));
  if (timestepping) PetscCall(PetscViewerHDF5GetTimestep(viewer, &timestep));
  PetscCall(PetscViewerHDF5GetBaseDimension2(viewer, &dim2));
  PetscCall(PetscViewerHDF5GetSPOutput(viewer, &spoutput));

  /* Create the dataspace for the dataset.
   *
   * dims - holds the current dimensions of the dataset
   *
   * maxDims - holds the maximum dimensions of the dataset (unlimited
   * for the number of time steps with the current dimensions for the
   * other dimensions; so only additional time steps can be added).
   *
   * chunkDims - holds the size of a single time step (required to
   * permit extending dataset).
   */
  dim       = 0;
  chunksize = 1;
  if (timestep >= 0) {
    dims[dim]      = timestep + 1;
    maxDims[dim]   = H5S_UNLIMITED;
    chunkDims[dim] = 1;
    ++dim;
  }
  PetscCall(PetscHDF5IntCast(xin->map->N / bs, dims + dim));

  maxDims[dim]   = dims[dim];
  chunkDims[dim] = PetscMax(1, dims[dim]);
  chunksize *= chunkDims[dim];
  ++dim;
  if (bs > 1 || dim2) {
    dims[dim]      = bs;
    maxDims[dim]   = dims[dim];
    chunkDims[dim] = PetscMax(1, dims[dim]);
    chunksize *= chunkDims[dim];
    ++dim;
  }
  #if defined(PETSC_USE_COMPLEX)
  dims[dim]      = 2;
  maxDims[dim]   = dims[dim];
  chunkDims[dim] = PetscMax(1, dims[dim]);
  chunksize *= chunkDims[dim];
  /* hdf5 chunks must be less than 4GB */
  if (chunksize > PETSC_HDF5_MAX_CHUNKSIZE / 64) {
    if (bs > 1 || dim2) {
      if (chunkDims[dim - 2] > (hsize_t)PetscSqrtReal((PetscReal)(PETSC_HDF5_MAX_CHUNKSIZE / 128))) chunkDims[dim - 2] = (hsize_t)PetscSqrtReal((PetscReal)(PETSC_HDF5_MAX_CHUNKSIZE / 128));
      if (chunkDims[dim - 1] > (hsize_t)PetscSqrtReal((PetscReal)(PETSC_HDF5_MAX_CHUNKSIZE / 128))) chunkDims[dim - 1] = (hsize_t)PetscSqrtReal((PetscReal)(PETSC_HDF5_MAX_CHUNKSIZE / 128));
    } else {
      chunkDims[dim - 1] = PETSC_HDF5_MAX_CHUNKSIZE / 128;
    }
  }
  ++dim;
  #else
  /* hdf5 chunks must be less than 4GB */
  if (chunksize > PETSC_HDF5_MAX_CHUNKSIZE / 64) {
    if (bs > 1 || dim2) {
      if (chunkDims[dim - 2] > (hsize_t)PetscSqrtReal((PetscReal)(PETSC_HDF5_MAX_CHUNKSIZE / 64))) chunkDims[dim - 2] = (hsize_t)PetscSqrtReal((PetscReal)(PETSC_HDF5_MAX_CHUNKSIZE / 64));
      if (chunkDims[dim - 1] > (hsize_t)PetscSqrtReal((PetscReal)(PETSC_HDF5_MAX_CHUNKSIZE / 64))) chunkDims[dim - 1] = (hsize_t)PetscSqrtReal((PetscReal)(PETSC_HDF5_MAX_CHUNKSIZE / 64));
    } else {
      chunkDims[dim - 1] = PETSC_HDF5_MAX_CHUNKSIZE / 64;
    }
  }
  #endif

  PetscCallHDF5Return(filespace, H5Screate_simple, ((int)dim, dims, maxDims));

  #if defined(PETSC_USE_REAL_SINGLE)
  memscalartype  = H5T_NATIVE_FLOAT;
  filescalartype = H5T_NATIVE_FLOAT;
  #elif defined(PETSC_USE_REAL___FLOAT128)
    #error "HDF5 output with 128 bit floats not supported."
  #elif defined(PETSC_USE_REAL___FP16)
    #error "HDF5 output with 16 bit floats not supported."
  #else
  memscalartype = H5T_NATIVE_DOUBLE;
  if (spoutput == PETSC_TRUE) filescalartype = H5T_NATIVE_FLOAT;
  else filescalartype = H5T_NATIVE_DOUBLE;
  #endif

  /* Create the dataset with default properties and close filespace */
  PetscCall(PetscObjectGetName((PetscObject)xin, &vecname));
  PetscCall(PetscStrlen(vecname, &len));
  PetscCheck(len, PetscObjectComm((PetscObject)viewer), PETSC_ERR_ARG_WRONG, "Object must be named");
  if (H5Lexists(group, vecname, H5P_DEFAULT) < 1) {
    /* Create chunk */
    PetscCallHDF5Return(chunkspace, H5Pcreate, (H5P_DATASET_CREATE));
    PetscCallHDF5(H5Pset_chunk, (chunkspace, (int)dim, chunkDims));

    PetscCallHDF5Return(dset_id, H5Dcreate2, (group, vecname, filescalartype, filespace, H5P_DEFAULT, chunkspace, H5P_DEFAULT));
    PetscCallHDF5(H5Pclose, (chunkspace));
  } else {
    PetscCallHDF5Return(dset_id, H5Dopen2, (group, vecname, H5P_DEFAULT));
    PetscCallHDF5(H5Dset_extent, (dset_id, dims));
  }
  PetscCallHDF5(H5Sclose, (filespace));

  /* Each process defines a dataset and writes it to the hyperslab in the file */
  dim = 0;
  if (timestep >= 0) {
    count[dim] = 1;
    ++dim;
  }
  PetscCall(PetscHDF5IntCast(xin->map->n / bs, count + dim));
  ++dim;
  if (bs > 1 || dim2) {
    count[dim] = bs;
    ++dim;
  }
  #if defined(PETSC_USE_COMPLEX)
  count[dim] = 2;
  ++dim;
  #endif
  if (xin->map->n > 0 || H5_VERSION_GE(1, 10, 0)) {
    PetscCallHDF5Return(memspace, H5Screate_simple, ((int)dim, count, NULL));
  } else {
    /* Can't create dataspace with zero for any dimension, so create null dataspace. */
    PetscCallHDF5Return(memspace, H5Screate, (H5S_NULL));
  }

  /* Select hyperslab in the file */
  PetscCall(VecGetOwnershipRange(xin, &low, NULL));
  dim = 0;
  if (timestep >= 0) {
    offset[dim] = timestep;
    ++dim;
  }
  PetscCall(PetscHDF5IntCast(low / bs, offset + dim));
  ++dim;
  if (bs > 1 || dim2) {
    offset[dim] = 0;
    ++dim;
  }
  #if defined(PETSC_USE_COMPLEX)
  offset[dim] = 0;
  ++dim;
  #endif
  if (xin->map->n > 0 || H5_VERSION_GE(1, 10, 0)) {
    PetscCallHDF5Return(filespace, H5Dget_space, (dset_id));
    PetscCallHDF5(H5Sselect_hyperslab, (filespace, H5S_SELECT_SET, offset, NULL, count, NULL));
  } else {
    /* Create null filespace to match null memspace. */
    PetscCallHDF5Return(filespace, H5Screate, (H5S_NULL));
  }

  PetscCall(VecGetArrayRead(xin, &x));
  PetscCallHDF5(H5Dwrite, (dset_id, memscalartype, memspace, filespace, hdf5->dxpl_id, x));
  PetscCallHDF5(H5Fflush, (file_id, H5F_SCOPE_GLOBAL));
  PetscCall(VecRestoreArrayRead(xin, &x));

  /* Close/release resources */
  PetscCallHDF5(H5Gclose, (group));
  PetscCallHDF5(H5Sclose, (filespace));
  PetscCallHDF5(H5Sclose, (memspace));
  PetscCallHDF5(H5Dclose, (dset_id));

  #if defined(PETSC_USE_COMPLEX)
  {
    PetscBool tru = PETSC_TRUE;
    PetscCall(PetscViewerHDF5WriteObjectAttribute(viewer, (PetscObject)xin, "complex", PETSC_BOOL, &tru));
  }
  #endif
  if (timestepping) PetscCall(PetscViewerHDF5WriteObjectAttribute(viewer, (PetscObject)xin, "timestepping", PETSC_BOOL, &timestepping));
  PetscCall(PetscInfo(xin, "Wrote Vec object with name %s\n", vecname));
  PetscFunctionReturn(PETSC_SUCCESS);
}
#endif

PetscErrorCode VecView_MPI(Vec xin, PetscViewer viewer)
{
  PetscBool isascii, isbinary, isdraw;
#if defined(PETSC_HAVE_MATHEMATICA)
  PetscBool ismathematica;
#endif
#if defined(PETSC_HAVE_HDF5)
  PetscBool ishdf5;
#endif
#if defined(PETSC_HAVE_MATLAB)
  PetscBool ismatlab;
#endif
#if defined(PETSC_HAVE_ADIOS)
  PetscBool isadios;
#endif
  PetscBool isglvis;

  PetscFunctionBegin;
  PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERASCII, &isascii));
  PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERBINARY, &isbinary));
  PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERDRAW, &isdraw));
#if defined(PETSC_HAVE_MATHEMATICA)
  PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERMATHEMATICA, &ismathematica));
#endif
#if defined(PETSC_HAVE_HDF5)
  PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERHDF5, &ishdf5));
#endif
#if defined(PETSC_HAVE_MATLAB)
  PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERMATLAB, &ismatlab));
#endif
  PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERGLVIS, &isglvis));
#if defined(PETSC_HAVE_ADIOS)
  PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERADIOS, &isadios));
#endif
  if (isascii) {
    PetscCall(VecView_MPI_ASCII(xin, viewer));
  } else if (isbinary) {
    PetscCall(VecView_MPI_Binary(xin, viewer));
  } else if (isdraw) {
    PetscViewerFormat format;
    PetscCall(PetscViewerGetFormat(viewer, &format));
    if (format == PETSC_VIEWER_DRAW_LG) {
      PetscCall(VecView_MPI_Draw_LG(xin, viewer));
    } else {
      PetscCall(VecView_MPI_Draw(xin, viewer));
    }
#if defined(PETSC_HAVE_MATHEMATICA)
  } else if (ismathematica) {
    PetscCall(PetscViewerMathematicaPutVector(viewer, xin));
#endif
#if defined(PETSC_HAVE_HDF5)
  } else if (ishdf5) {
    PetscCall(VecView_MPI_HDF5(xin, viewer));
#endif
#if defined(PETSC_HAVE_ADIOS)
  } else if (isadios) {
    PetscCall(VecView_MPI_ADIOS(xin, viewer));
#endif
#if defined(PETSC_HAVE_MATLAB)
  } else if (ismatlab) {
    PetscCall(VecView_MPI_Matlab(xin, viewer));
#endif
  } else if (isglvis) PetscCall(VecView_GLVis(xin, viewer));
  PetscFunctionReturn(PETSC_SUCCESS);
}

PetscErrorCode VecGetSize_MPI(Vec xin, PetscInt *N)
{
  PetscFunctionBegin;
  *N = xin->map->N;
  PetscFunctionReturn(PETSC_SUCCESS);
}

PetscErrorCode VecGetValues_MPI(Vec xin, PetscInt ni, const PetscInt ix[], PetscScalar y[])
{
  const PetscScalar *xx;
  const PetscInt     start = xin->map->range[xin->stash.rank];

  PetscFunctionBegin;
  PetscCall(VecGetArrayRead(xin, &xx));
  for (PetscInt i = 0; i < ni; i++) {
    if (xin->stash.ignorenegidx && ix[i] < 0) continue;
    const PetscInt tmp = ix[i] - start;

    PetscCheck(tmp >= 0 && tmp < xin->map->n, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Can only get local values, trying %" PetscInt_FMT, ix[i]);
    y[i] = xx[tmp];
  }
  PetscCall(VecRestoreArrayRead(xin, &xx));
  PetscFunctionReturn(PETSC_SUCCESS);
}

PetscErrorCode VecSetValues_MPI(Vec xin, PetscInt ni, const PetscInt ix[], const PetscScalar y[], InsertMode addv)
{
  const PetscBool   ignorenegidx = xin->stash.ignorenegidx;
  const PetscBool   donotstash   = xin->stash.donotstash;
  const PetscMPIInt rank         = xin->stash.rank;
  const PetscInt   *owners       = xin->map->range;
  const PetscInt    start = owners[rank], end = owners[rank + 1];
  PetscScalar      *xx;

  PetscFunctionBegin;
  if (PetscDefined(USE_DEBUG)) {
    PetscCheck(xin->stash.insertmode != INSERT_VALUES || addv != ADD_VALUES, PETSC_COMM_SELF, PETSC_ERR_ARG_WRONGSTATE, "You have already inserted values; you cannot now add");
    PetscCheck(xin->stash.insertmode != ADD_VALUES || addv != INSERT_VALUES, PETSC_COMM_SELF, PETSC_ERR_ARG_WRONGSTATE, "You have already added values; you cannot now insert");
  }
  PetscCall(VecGetArray(xin, &xx));
  xin->stash.insertmode = addv;
  for (PetscInt i = 0; i < ni; ++i) {
    PetscInt    row;
    PetscScalar yv = y ? y[i] : 0;

    if (ignorenegidx && ix[i] < 0) continue;
    PetscCheck(ix[i] >= 0, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Out of range index value %" PetscInt_FMT " cannot be negative", ix[i]);
    if ((row = ix[i]) >= start && row < end) {
      if (addv == INSERT_VALUES) {
        xx[row - start] = yv;
      } else {
        xx[row - start] += yv;
      }
    } else if (!donotstash) {
      PetscCheck(ix[i] < xin->map->N, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Out of range index value %" PetscInt_FMT ", should be less than %" PetscInt_FMT, ix[i], xin->map->N);
      PetscCall(VecStashValue_Private(&xin->stash, row, yv));
    }
  }
  PetscCall(VecRestoreArray(xin, &xx));
  PetscFunctionReturn(PETSC_SUCCESS);
}

PetscErrorCode VecSetValuesBlocked_MPI(Vec xin, PetscInt ni, const PetscInt ix[], const PetscScalar yin[], InsertMode addv)
{
  PetscMPIInt  rank   = xin->stash.rank;
  PetscInt    *owners = xin->map->range, start = owners[rank];
  PetscInt     end = owners[rank + 1], i, row, bs = xin->map->bs, j;
  PetscScalar *xx, *y = (PetscScalar *)yin;

  PetscFunctionBegin;
  PetscCall(VecGetArray(xin, &xx));
  if (PetscDefined(USE_DEBUG)) {
    PetscCheck(xin->stash.insertmode != INSERT_VALUES || addv != ADD_VALUES, PETSC_COMM_SELF, PETSC_ERR_ARG_WRONGSTATE, "You have already inserted values; you cannot now add");
    PetscCheck(xin->stash.insertmode != ADD_VALUES || addv != INSERT_VALUES, PETSC_COMM_SELF, PETSC_ERR_ARG_WRONGSTATE, "You have already added values; you cannot now insert");
  }
  xin->stash.insertmode = addv;

  if (addv == INSERT_VALUES) {
    for (i = 0; i < ni; i++) {
      if ((row = bs * ix[i]) >= start && row < end) {
        for (j = 0; j < bs; j++) xx[row - start + j] = y ? y[j] : 0.0;
      } else if (!xin->stash.donotstash) {
        if (ix[i] < 0) {
          if (y) y += bs;
          continue;
        }
        PetscCheck(ix[i] < xin->map->N, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Out of range index value %" PetscInt_FMT ", should be less than %" PetscInt_FMT, ix[i], xin->map->N);
        PetscCall(VecStashValuesBlocked_Private(&xin->bstash, ix[i], y));
      }
      if (y) y += bs;
    }
  } else {
    for (i = 0; i < ni; i++) {
      if ((row = bs * ix[i]) >= start && row < end) {
        for (j = 0; j < bs; j++) xx[row - start + j] += y ? y[j] : 0.0;
      } else if (!xin->stash.donotstash) {
        if (ix[i] < 0) {
          if (y) y += bs;
          continue;
        }
        PetscCheck(ix[i] <= xin->map->N, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Out of range index value %" PetscInt_FMT ", should be less than %" PetscInt_FMT, ix[i], xin->map->N);
        PetscCall(VecStashValuesBlocked_Private(&xin->bstash, ix[i], y));
      }
      if (y) y += bs;
    }
  }
  PetscCall(VecRestoreArray(xin, &xx));
  PetscFunctionReturn(PETSC_SUCCESS);
}

/*
   Since nsends or nreceives may be zero we add 1 in certain mallocs
to make sure we never malloc an empty one.
*/
PetscErrorCode VecAssemblyBegin_MPI(Vec xin)
{
  PetscInt   *owners = xin->map->range, *bowners, i, bs, nstash, reallocs;
  PetscMPIInt size;
  InsertMode  addv;
  MPI_Comm    comm;

  PetscFunctionBegin;
  PetscCall(PetscObjectGetComm((PetscObject)xin, &comm));
  if (xin->stash.donotstash) PetscFunctionReturn(PETSC_SUCCESS);

  PetscCallMPI(MPIU_Allreduce((PetscEnum *)&xin->stash.insertmode, (PetscEnum *)&addv, 1, MPIU_ENUM, MPI_BOR, comm));
  PetscCheck(addv != (ADD_VALUES | INSERT_VALUES), comm, PETSC_ERR_ARG_NOTSAMETYPE, "Some processors inserted values while others added");
  xin->stash.insertmode  = addv; /* in case this processor had no cache */
  xin->bstash.insertmode = addv; /* Block stash implicitly tracks InsertMode of scalar stash */

  PetscCall(VecGetBlockSize(xin, &bs));
  PetscCallMPI(MPI_Comm_size(PetscObjectComm((PetscObject)xin), &size));
  if (!xin->bstash.bowners && xin->map->bs != -1) {
    PetscCall(PetscMalloc1(size + 1, &bowners));
    for (i = 0; i < size + 1; i++) bowners[i] = owners[i] / bs;
    xin->bstash.bowners = bowners;
  } else bowners = xin->bstash.bowners;

  PetscCall(VecStashScatterBegin_Private(&xin->stash, owners));
  PetscCall(VecStashScatterBegin_Private(&xin->bstash, bowners));
  PetscCall(VecStashGetInfo_Private(&xin->stash, &nstash, &reallocs));
  PetscCall(PetscInfo(xin, "Stash has %" PetscInt_FMT " entries, uses %" PetscInt_FMT " mallocs.\n", nstash, reallocs));
  PetscCall(VecStashGetInfo_Private(&xin->bstash, &nstash, &reallocs));
  PetscCall(PetscInfo(xin, "Block-Stash has %" PetscInt_FMT " entries, uses %" PetscInt_FMT " mallocs.\n", nstash, reallocs));
  PetscFunctionReturn(PETSC_SUCCESS);
}

PetscErrorCode VecAssemblyEnd_MPI(Vec vec)
{
  PetscInt     base, i, j, *row, flg, bs;
  PetscMPIInt  n;
  PetscScalar *val, *vv, *array, *xarray;

  PetscFunctionBegin;
  if (!vec->stash.donotstash) {
    PetscCall(VecGetArray(vec, &xarray));
    PetscCall(VecGetBlockSize(vec, &bs));
    base = vec->map->range[vec->stash.rank];

    /* Process the stash */
    while (1) {
      PetscCall(VecStashScatterGetMesg_Private(&vec->stash, &n, &row, &val, &flg));
      if (!flg) break;
      if (vec->stash.insertmode == ADD_VALUES) {
        for (i = 0; i < n; i++) xarray[row[i] - base] += val[i];
      } else if (vec->stash.insertmode == INSERT_VALUES) {
        for (i = 0; i < n; i++) xarray[row[i] - base] = val[i];
      } else SETERRQ(PETSC_COMM_SELF, PETSC_ERR_ARG_CORRUPT, "Insert mode is not set correctly; corrupted vector");
    }
    PetscCall(VecStashScatterEnd_Private(&vec->stash));

    /* now process the block-stash */
    while (1) {
      PetscCall(VecStashScatterGetMesg_Private(&vec->bstash, &n, &row, &val, &flg));
      if (!flg) break;
      for (i = 0; i < n; i++) {
        array = xarray + row[i] * bs - base;
        vv    = val + i * bs;
        if (vec->stash.insertmode == ADD_VALUES) {
          for (j = 0; j < bs; j++) array[j] += vv[j];
        } else if (vec->stash.insertmode == INSERT_VALUES) {
          for (j = 0; j < bs; j++) array[j] = vv[j];
        } else SETERRQ(PETSC_COMM_SELF, PETSC_ERR_ARG_CORRUPT, "Insert mode is not set correctly; corrupted vector");
      }
    }
    PetscCall(VecStashScatterEnd_Private(&vec->bstash));
    PetscCall(VecRestoreArray(vec, &xarray));
  }
  vec->stash.insertmode = NOT_SET_VALUES;
  PetscFunctionReturn(PETSC_SUCCESS);
}

PetscErrorCode VecSetPreallocationCOO_MPI(Vec x, PetscCount coo_n, const PetscInt coo_i[])
{
  PetscInt    m, M, rstart, rend;
  Vec_MPI    *vmpi = (Vec_MPI *)x->data;
  PetscCount  k, p, q, rem; /* Loop variables over coo arrays */
  PetscMPIInt size;
  MPI_Comm    comm;

  PetscFunctionBegin;
  PetscCall(PetscObjectGetComm((PetscObject)x, &comm));
  PetscCallMPI(MPI_Comm_size(comm, &size));
  PetscCall(VecResetPreallocationCOO_MPI(x));

  PetscCall(PetscLayoutSetUp(x->map));
  PetscCall(VecGetOwnershipRange(x, &rstart, &rend));
  PetscCall(VecGetLocalSize(x, &m));
  PetscCall(VecGetSize(x, &M));

  /* Sort COOs along with a permutation array, so that negative indices come    */
  /* first, then local ones, then remote ones.                                  */
  PetscCount n1 = coo_n, nneg, *perm;
  PetscInt  *i1; /* Copy of input COOs along with a permutation array */
  PetscCall(PetscMalloc1(n1, &i1));
  PetscCall(PetscMalloc1(n1, &perm));
  PetscCall(PetscArraycpy(i1, coo_i, n1)); /* Make a copy since we'll modify it */
  for (k = 0; k < n1; k++) perm[k] = k;

  /* Manipulate i1[] so that entries with negative indices will have the smallest
     index, local entries will have greater but negative indices, and remote entries
     will have positive indices.
  */
  for (k = 0; k < n1; k++) {
    if (i1[k] < 0) {
      if (x->stash.ignorenegidx) i1[k] = PETSC_INT_MIN; /* e.g., -2^31, minimal to move them ahead */
      else SETERRQ(PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Found a negative index in VecSetPreallocateCOO() but VEC_IGNORE_NEGATIVE_INDICES was not set");
    } else if (i1[k] >= rstart && i1[k] < rend) {
      i1[k] -= PETSC_INT_MAX; /* e.g., minus 2^31-1 to shift local rows to range of [-PETSC_INT_MAX, -1] */
    } else {
      PetscCheck(i1[k] < M, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Found index %" PetscInt_FMT " in VecSetPreallocateCOO() larger than the global size %" PetscInt_FMT, i1[k], M);
      if (x->stash.donotstash) i1[k] = PETSC_INT_MIN; /* Ignore off-proc indices as if they were negative */
    }
  }

  /* Sort the indices, after that, [0,nneg) have ignored entries, [nneg,rem) have local entries and [rem,n1) have remote entries */
  PetscCall(PetscSortIntWithCountArray(n1, i1, perm));
  for (k = 0; k < n1; k++) {
    if (i1[k] > PETSC_INT_MIN) break;
  } /* Advance k to the first entry we need to take care of */
  nneg = k;
  PetscCall(PetscSortedIntUpperBound(i1, nneg, n1, rend - 1 - PETSC_INT_MAX, &rem)); /* rem is upper bound of the last local row */
  for (k = nneg; k < rem; k++) i1[k] += PETSC_INT_MAX;                               /* Revert indices of local entries */

  /*           Build stuff for local entries                                    */
  PetscCount tot1, *jmap1, *perm1;
  PetscCall(PetscCalloc1(m + 1, &jmap1));
  for (k = nneg; k < rem; k++) jmap1[i1[k] - rstart + 1]++; /* Count repeats of each local entry */
  for (k = 0; k < m; k++) jmap1[k + 1] += jmap1[k];         /* Transform jmap1[] to CSR-like data structure */
  tot1 = jmap1[m];
  PetscAssert(tot1 == rem - nneg, PETSC_COMM_SELF, PETSC_ERR_PLIB, "Unexpected errors in VecSetPreallocationCOO_MPI");
  PetscCall(PetscMalloc1(tot1, &perm1));
  PetscCall(PetscArraycpy(perm1, perm + nneg, tot1));

  /*        Record the permutation array for filling the send buffer            */
  PetscCount *Cperm;
  PetscCall(PetscMalloc1(n1 - rem, &Cperm));
  PetscCall(PetscArraycpy(Cperm, perm + rem, n1 - rem));
  PetscCall(PetscFree(perm));

  /*           Send remote entries to their owner                                  */
  /* Find which entries should be sent to which remote ranks*/
  PetscInt        nsend = 0; /* Number of MPI ranks to send data to */
  PetscMPIInt    *sendto;    /* [nsend], storing remote ranks */
  PetscInt       *nentries;  /* [nsend], storing number of entries sent to remote ranks; Assume PetscInt is big enough for this count, and error if not */
  const PetscInt *ranges;
  PetscInt        maxNsend = size >= 128 ? 128 : size; /* Assume max 128 neighbors; realloc when needed */

  PetscCall(PetscLayoutGetRanges(x->map, &ranges));
  PetscCall(PetscMalloc2(maxNsend, &sendto, maxNsend, &nentries));
  for (k = rem; k < n1;) {
    PetscMPIInt owner;
    PetscInt    firstRow, lastRow;

    /* Locate a row range */
    firstRow = i1[k]; /* first row of this owner */
    PetscCall(PetscLayoutFindOwner(x->map, firstRow, &owner));
    lastRow = ranges[owner + 1] - 1; /* last row of this owner */

    /* Find the first index 'p' in [k,n) with i[p] belonging to next owner */
    PetscCall(PetscSortedIntUpperBound(i1, k, n1, lastRow, &p));

    /* All entries in [k,p) belong to this remote owner */
    if (nsend >= maxNsend) { /* Double the remote ranks arrays if not long enough */
      PetscMPIInt *sendto2;
      PetscInt    *nentries2;
      PetscInt     maxNsend2 = (maxNsend <= size / 2) ? maxNsend * 2 : size;

      PetscCall(PetscMalloc2(maxNsend2, &sendto2, maxNsend2, &nentries2));
      PetscCall(PetscArraycpy(sendto2, sendto, maxNsend));
      PetscCall(PetscArraycpy(nentries2, nentries2, maxNsend + 1));
      PetscCall(PetscFree2(sendto, nentries2));
      sendto   = sendto2;
      nentries = nentries2;
      maxNsend = maxNsend2;
    }
    sendto[nsend] = owner;
    PetscCall(PetscIntCast(p - k, &nentries[nsend]));
    nsend++;
    k = p;
  }

  /* Build 1st SF to know offsets on remote to send data */
  PetscSF      sf1;
  PetscInt     nroots = 1, nroots2 = 0;
  PetscInt     nleaves = nsend, nleaves2 = 0;
  PetscInt    *offsets;
  PetscSFNode *iremote;

  PetscCall(PetscSFCreate(comm, &sf1));
  PetscCall(PetscMalloc1(nsend, &iremote));
  PetscCall(PetscMalloc1(nsend, &offsets));
  for (k = 0; k < nsend; k++) {
    iremote[k].rank  = sendto[k];
    iremote[k].index = 0;
    nleaves2 += nentries[k];
    PetscCheck(nleaves2 >= 0, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Number of SF leaves is too large for PetscInt");
  }
  PetscCall(PetscSFSetGraph(sf1, nroots, nleaves, NULL, PETSC_OWN_POINTER, iremote, PETSC_OWN_POINTER));
  PetscCall(PetscSFFetchAndOpWithMemTypeBegin(sf1, MPIU_INT, PETSC_MEMTYPE_HOST, &nroots2 /*rootdata*/, PETSC_MEMTYPE_HOST, nentries /*leafdata*/, PETSC_MEMTYPE_HOST, offsets /*leafupdate*/, MPI_SUM));
  PetscCall(PetscSFFetchAndOpEnd(sf1, MPIU_INT, &nroots2, nentries, offsets, MPI_SUM)); /* Would nroots2 overflow, we check offsets[] below */
  PetscCall(PetscSFDestroy(&sf1));
  PetscAssert(nleaves2 == n1 - rem, PETSC_COMM_SELF, PETSC_ERR_PLIB, "nleaves2 %" PetscInt_FMT " != number of remote entries %" PetscCount_FMT, nleaves2, n1 - rem);

  /* Build 2nd SF to send remote COOs to their owner */
  PetscSF sf2;
  nroots  = nroots2;
  nleaves = nleaves2;
  PetscCall(PetscSFCreate(comm, &sf2));
  PetscCall(PetscSFSetFromOptions(sf2));
  PetscCall(PetscMalloc1(nleaves, &iremote));
  p = 0;
  for (k = 0; k < nsend; k++) {
    PetscCheck(offsets[k] >= 0, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Number of SF roots is too large for PetscInt");
    for (q = 0; q < nentries[k]; q++, p++) {
      iremote[p].rank = sendto[k];
      PetscCall(PetscIntCast(offsets[k] + q, &iremote[p].index));
    }
  }
  PetscCall(PetscSFSetGraph(sf2, nroots, nleaves, NULL, PETSC_OWN_POINTER, iremote, PETSC_OWN_POINTER));

  /* Send the remote COOs to their owner */
  PetscInt    n2 = nroots, *i2; /* Buffers for received COOs from other ranks, along with a permutation array */
  PetscCount *perm2;
  PetscCall(PetscMalloc1(n2, &i2));
  PetscCall(PetscMalloc1(n2, &perm2));
  PetscCall(PetscSFReduceWithMemTypeBegin(sf2, MPIU_INT, PETSC_MEMTYPE_HOST, i1 + rem, PETSC_MEMTYPE_HOST, i2, MPI_REPLACE));
  PetscCall(PetscSFReduceEnd(sf2, MPIU_INT, i1 + rem, i2, MPI_REPLACE));

  PetscCall(PetscFree(i1));
  PetscCall(PetscFree(offsets));
  PetscCall(PetscFree2(sendto, nentries));

  /* Sort received COOs along with a permutation array            */
  PetscCount  *imap2;
  PetscCount  *jmap2, nnz2;
  PetscScalar *sendbuf, *recvbuf;
  PetscInt     old;
  PetscCount   sendlen = n1 - rem, recvlen = n2;

  for (k = 0; k < n2; k++) perm2[k] = k;
  PetscCall(PetscSortIntWithCountArray(n2, i2, perm2));

  /* nnz2 will be # of unique entries in the recvbuf */
  nnz2 = n2;
  for (k = 1; k < n2; k++) {
    if (i2[k] == i2[k - 1]) nnz2--;
  }

  /* Build imap2[] and jmap2[] for each unique entry */
  PetscCall(PetscMalloc4(nnz2, &imap2, nnz2 + 1, &jmap2, sendlen, &sendbuf, recvlen, &recvbuf));
  p        = -1;
  old      = -1;
  jmap2[0] = 0;
  jmap2++;
  for (k = 0; k < n2; k++) {
    if (i2[k] != old) { /* Meet a new entry */
      p++;
      imap2[p] = i2[k] - rstart;
      jmap2[p] = 1;
      old      = i2[k];
    } else {
      jmap2[p]++;
    }
  }
  jmap2--;
  for (k = 0; k < nnz2; k++) jmap2[k + 1] += jmap2[k];

  PetscCall(PetscFree(i2));

  vmpi->coo_n = coo_n;
  vmpi->tot1  = tot1;
  vmpi->jmap1 = jmap1;
  vmpi->perm1 = perm1;
  vmpi->nnz2  = nnz2;
  vmpi->imap2 = imap2;
  vmpi->jmap2 = jmap2;
  vmpi->perm2 = perm2;

  vmpi->Cperm   = Cperm;
  vmpi->sendbuf = sendbuf;
  vmpi->recvbuf = recvbuf;
  vmpi->sendlen = sendlen;
  vmpi->recvlen = recvlen;
  vmpi->coo_sf  = sf2;
  PetscFunctionReturn(PETSC_SUCCESS);
}

PetscErrorCode VecSetValuesCOO_MPI(Vec x, const PetscScalar v[], InsertMode imode)
{
  Vec_MPI          *vmpi = (Vec_MPI *)x->data;
  PetscInt          m;
  PetscScalar      *a, *sendbuf = vmpi->sendbuf, *recvbuf = vmpi->recvbuf;
  const PetscCount *jmap1 = vmpi->jmap1;
  const PetscCount *perm1 = vmpi->perm1;
  const PetscCount *imap2 = vmpi->imap2;
  const PetscCount *jmap2 = vmpi->jmap2;
  const PetscCount *perm2 = vmpi->perm2;
  const PetscCount *Cperm = vmpi->Cperm;
  const PetscCount  nnz2  = vmpi->nnz2;

  PetscFunctionBegin;
  PetscCall(VecGetLocalSize(x, &m));
  PetscCall(VecGetArray(x, &a));

  /* Pack entries to be sent to remote */
  for (PetscInt i = 0; i < vmpi->sendlen; i++) sendbuf[i] = v[Cperm[i]];

  /* Send remote entries to their owner and overlap the communication with local computation */
  PetscCall(PetscSFReduceWithMemTypeBegin(vmpi->coo_sf, MPIU_SCALAR, PETSC_MEMTYPE_HOST, sendbuf, PETSC_MEMTYPE_HOST, recvbuf, MPI_REPLACE));
  /* Add local entries to A and B */
  for (PetscInt i = 0; i < m; i++) { /* All entries in a[] are either zero'ed or added with a value (i.e., initialized) */
    PetscScalar sum = 0.0;           /* Do partial summation first to improve numerical stability */
    for (PetscCount k = jmap1[i]; k < jmap1[i + 1]; k++) sum += v[perm1[k]];
    a[i] = (imode == INSERT_VALUES ? 0.0 : a[i]) + sum;
  }
  PetscCall(PetscSFReduceEnd(vmpi->coo_sf, MPIU_SCALAR, sendbuf, recvbuf, MPI_REPLACE));

  /* Add received remote entries to A and B */
  for (PetscInt i = 0; i < nnz2; i++) {
    for (PetscCount k = jmap2[i]; k < jmap2[i + 1]; k++) a[imap2[i]] += recvbuf[perm2[k]];
  }

  PetscCall(VecRestoreArray(x, &a));
  PetscFunctionReturn(PETSC_SUCCESS);
}
