xref: /petsc/src/dm/impls/plex/plexnatural.c (revision 3ba1676111f5c958fe6c2729b46ca4d523958bb3)

#include <petsc/private/dmpleximpl.h> /*I      "petscdmplex.h"   I*/

/*@
  DMPlexSetMigrationSF - Sets the `PetscSF` for migrating from a parent `DM` into this `DM`

  Logically Collective on dm

  Input Parameters:
+ dm        - The `DM`
- naturalSF - The `PetscSF`

  Level: intermediate

  Note:
  It is necessary to call this in order to have `DMCreateSubDM()` or `DMCreateSuperDM()` build the Global-To-Natural map

.seealso: [](chapter_unstructured), `DM`, `DMPLEX`, `PetscSF`, `DMPlexDistribute()`, `DMPlexDistributeField()`, `DMPlexCreateMigrationSF()`, `DMPlexGetMigrationSF()`
@*/
PetscErrorCode DMPlexSetMigrationSF(DM dm, PetscSF migrationSF)
{
  PetscFunctionBegin;
  dm->sfMigration = migrationSF;
  PetscCall(PetscObjectReference((PetscObject)migrationSF));
  PetscFunctionReturn(PETSC_SUCCESS);
}

/*@
  DMPlexGetMigrationSF - Gets the `PetscSF` for migrating from a parent `DM` into this `DM`

  Note Collective

  Input Parameter:
. dm          - The `DM`

  Output Parameter:
. migrationSF - The `PetscSF`

  Level: intermediate

.seealso: [](chapter_unstructured), `DM`, `DMPLEX`, `PetscSF`, `DMPlexDistribute()`, `DMPlexDistributeField()`, `DMPlexCreateMigrationSF()`, `DMPlexSetMigrationSF`
@*/
PetscErrorCode DMPlexGetMigrationSF(DM dm, PetscSF *migrationSF)
{
  PetscFunctionBegin;
  *migrationSF = dm->sfMigration;
  PetscFunctionReturn(PETSC_SUCCESS);
}

/*@
  DMPlexSetGlobalToNaturalSF - Sets the `PetscSF` for mapping Global `Vec` to the Natural `Vec`

  Input Parameters:
+ dm          - The `DM`
- naturalSF   - The `PetscSF`

  Level: intermediate

.seealso: [](chapter_unstructured), `DM`, `DMPLEX`, `PetscSF`, `DMPlexDistribute()`, `DMPlexDistributeField()`, `DMPlexCreateGlobalToNaturalSF()`, `DMPlexGetGlobaltoNaturalSF()`
@*/
PetscErrorCode DMPlexSetGlobalToNaturalSF(DM dm, PetscSF naturalSF)
{
  PetscFunctionBegin;
  dm->sfNatural = naturalSF;
  PetscCall(PetscObjectReference((PetscObject)naturalSF));
  dm->useNatural = PETSC_TRUE;
  PetscFunctionReturn(PETSC_SUCCESS);
}

/*@
  DMPlexGetGlobalToNaturalSF - Gets the `PetscSF` for mapping Global `Vec` to the Natural `Vec`

  Input Parameter:
. dm          - The `DM`

  Output Parameter:
. naturalSF   - The `PetscSF`

  Level: intermediate

.seealso: [](chapter_unstructured), `DM`, `DMPLEX`, `PetscSF`, `DMPlexDistribute()`, `DMPlexDistributeField()`, `DMPlexCreateGlobalToNaturalSF()`, `DMPlexSetGlobaltoNaturalSF`
@*/
PetscErrorCode DMPlexGetGlobalToNaturalSF(DM dm, PetscSF *naturalSF)
{
  PetscFunctionBegin;
  *naturalSF = dm->sfNatural;
  PetscFunctionReturn(PETSC_SUCCESS);
}

/*@
  DMPlexCreateGlobalToNaturalSF - Creates the `PetscSF` for mapping Global `Vec` to the Natural `Vec`

  Input Parameters:
+ dm          - The redistributed `DM`
. section     - The local `PetscSection` describing the `Vec` before the mesh was distributed, or NULL if not available
- sfMigration - The `PetscSF` used to distribute the mesh, or NULL if it cannot be computed

  Output Parameter:
. sfNatural   - `PetscSF` for mapping the `Vec` in PETSc ordering to the canonical ordering

  Level: intermediate

  Note:
  This is not typically called by the user.

.seealso: [](chapter_unstructured), `DM`, `DMPLEX`, `PetscSF`, `PetscSection`, `DMPlexDistribute()`, `DMPlexDistributeField()`
 @*/
PetscErrorCode DMPlexCreateGlobalToNaturalSF(DM dm, PetscSection section, PetscSF sfMigration, PetscSF *sfNatural)
{
  MPI_Comm     comm;
  PetscSF      sf, sfEmbed, sfField;
  PetscSection gSection, sectionDist, gLocSection;
  PetscInt    *spoints, *remoteOffsets;
  PetscInt     ssize, pStart, pEnd, p, localSize, maxStorageSize;
  PetscBool    destroyFlag = PETSC_FALSE, debug = PETSC_FALSE;

  PetscFunctionBegin;
  PetscCall(PetscObjectGetComm((PetscObject)dm, &comm));
  if (!sfMigration) {
    /* If sfMigration is missing, sfNatural cannot be computed and is set to NULL */
    *sfNatural = NULL;
    PetscFunctionReturn(PETSC_SUCCESS);
  } else if (!section) {
    /* If the sequential section is not provided (NULL), it is reconstructed from the parallel section */
    PetscSF      sfMigrationInv;
    PetscSection localSection;

    PetscCall(DMGetLocalSection(dm, &localSection));
    PetscCall(PetscSFCreateInverseSF(sfMigration, &sfMigrationInv));
    PetscCall(PetscSectionCreate(PetscObjectComm((PetscObject)dm), &section));
    PetscCall(PetscSFDistributeSection(sfMigrationInv, localSection, NULL, section));
    PetscCall(PetscSFDestroy(&sfMigrationInv));
    destroyFlag = PETSC_TRUE;
  }
  if (debug) PetscCall(PetscSFView(sfMigration, NULL));
  /* Create a new section from distributing the original section */
  PetscCall(PetscSectionCreate(comm, &sectionDist));
  PetscCall(PetscSFDistributeSection(sfMigration, section, &remoteOffsets, sectionDist));
  PetscCall(PetscObjectSetName((PetscObject)sectionDist, "Migrated Section"));
  if (debug) PetscCall(PetscSectionView(sectionDist, NULL));
  PetscCall(DMSetLocalSection(dm, sectionDist));
  /* If a sequential section is provided but no dof is affected, sfNatural cannot be computed and is set to NULL */
  PetscCall(PetscSectionGetStorageSize(sectionDist, &localSize));
  PetscCallMPI(MPI_Allreduce(&localSize, &maxStorageSize, 1, MPI_INT, MPI_MAX, PetscObjectComm((PetscObject)dm)));
  if (maxStorageSize) {
    const PetscInt *leaves;
    PetscInt       *sortleaves, *indices;
    PetscInt        Nl;

    /* Get a pruned version of migration SF */
    PetscCall(DMGetGlobalSection(dm, &gSection));
    if (debug) PetscCall(PetscSectionView(gSection, NULL));
    PetscCall(PetscSFGetGraph(sfMigration, NULL, &Nl, &leaves, NULL));
    PetscCall(PetscSectionGetChart(gSection, &pStart, &pEnd));
    for (p = pStart, ssize = 0; p < pEnd; ++p) {
      PetscInt dof, off;

      PetscCall(PetscSectionGetDof(gSection, p, &dof));
      PetscCall(PetscSectionGetOffset(gSection, p, &off));
      if ((dof > 0) && (off >= 0)) ++ssize;
    }
    PetscCall(PetscMalloc3(ssize, &spoints, Nl, &sortleaves, Nl, &indices));
    for (p = 0; p < Nl; ++p) {
      sortleaves[p] = leaves ? leaves[p] : p;
      indices[p]    = p;
    }
    PetscCall(PetscSortIntWithArray(Nl, sortleaves, indices));
    for (p = pStart, ssize = 0; p < pEnd; ++p) {
      PetscInt dof, off, loc;

      PetscCall(PetscSectionGetDof(gSection, p, &dof));
      PetscCall(PetscSectionGetOffset(gSection, p, &off));
      if ((dof > 0) && (off >= 0)) {
        PetscCall(PetscFindInt(p, Nl, sortleaves, &loc));
        PetscCheck(loc >= 0, PETSC_COMM_SELF, PETSC_ERR_ARG_WRONG, "Point %" PetscInt_FMT " with nonzero dof is not a leaf of the migration SF", p);
        spoints[ssize++] = indices[loc];
      }
    }
    PetscCall(PetscSFCreateEmbeddedLeafSF(sfMigration, ssize, spoints, &sfEmbed));
    PetscCall(PetscObjectSetName((PetscObject)sfEmbed, "Embedded SF"));
    PetscCall(PetscFree3(spoints, sortleaves, indices));
    if (debug) PetscCall(PetscSFView(sfEmbed, NULL));
    /* Create the SF associated with this section
         Roots are natural dofs, leaves are global dofs */
    PetscCall(DMGetPointSF(dm, &sf));
    PetscCall(PetscSectionCreateGlobalSection(sectionDist, sf, PETSC_TRUE, PETSC_TRUE, &gLocSection));
    PetscCall(PetscSFCreateSectionSF(sfEmbed, section, remoteOffsets, gLocSection, &sfField));
    PetscCall(PetscSFDestroy(&sfEmbed));
    PetscCall(PetscSectionDestroy(&gLocSection));
    PetscCall(PetscObjectSetName((PetscObject)sfField, "Natural-to-Global SF"));
    if (debug) PetscCall(PetscSFView(sfField, NULL));
    /* Invert the field SF
         Roots are global dofs, leaves are natural dofs */
    PetscCall(PetscSFCreateInverseSF(sfField, sfNatural));
    PetscCall(PetscObjectSetName((PetscObject)*sfNatural, "Global-to-Natural SF"));
    PetscCall(PetscObjectViewFromOptions((PetscObject)*sfNatural, NULL, "-globaltonatural_sf_view"));
    /* Clean up */
    PetscCall(PetscSFDestroy(&sfField));
  } else {
    *sfNatural = NULL;
  }
  PetscCall(PetscSectionDestroy(&sectionDist));
  PetscCall(PetscFree(remoteOffsets));
  if (destroyFlag) PetscCall(PetscSectionDestroy(&section));
  PetscFunctionReturn(PETSC_SUCCESS);
}

/*@
  DMPlexGlobalToNaturalBegin - Rearranges a global `Vec` in the natural order.

  Collective on dm

  Input Parameters:
+ dm - The distributed `DMPLEX`
- gv - The global `Vec`

  Output Parameters:
. nv - `Vec` in the canonical ordering distributed over all processors associated with gv

  Level: intermediate

  Note:
  The user must call `DMSetUseNatural`(dm, `PETSC_TRUE`) before `DMPlexDistribute()`.

.seealso: [](chapter_unstructured), `DM`, `DMPLEX`, `Vec`, `DMPlexDistribute()`, `DMPlexDistributeField()`, `DMPlexNaturalToGlobalBegin()`, `DMPlexGlobalToNaturalEnd()`
@*/
PetscErrorCode DMPlexGlobalToNaturalBegin(DM dm, Vec gv, Vec nv)
{
  const PetscScalar *inarray;
  PetscScalar       *outarray;
  PetscMPIInt        size;

  PetscFunctionBegin;
  PetscCall(PetscLogEventBegin(DMPLEX_GlobalToNaturalBegin, dm, 0, 0, 0));
  PetscCallMPI(MPI_Comm_size(PetscObjectComm((PetscObject)dm), &size));
  if (dm->sfNatural) {
    PetscCall(VecGetArray(nv, &outarray));
    PetscCall(VecGetArrayRead(gv, &inarray));
    PetscCall(PetscSFBcastBegin(dm->sfNatural, MPIU_SCALAR, (PetscScalar *)inarray, outarray, MPI_REPLACE));
    PetscCall(VecRestoreArrayRead(gv, &inarray));
    PetscCall(VecRestoreArray(nv, &outarray));
  } else if (size == 1) {
    PetscCall(VecCopy(gv, nv));
  } else {
    PetscCheck(!dm->useNatural, PetscObjectComm((PetscObject)dm), PETSC_ERR_PLIB, "DM global to natural SF not present.\nIf DMPlexDistribute() was called and a section was defined, report to petsc-maint@mcs.anl.gov.");
    SETERRQ(PetscObjectComm((PetscObject)dm), PETSC_ERR_ARG_WRONGSTATE, "DM global to natural SF was not created.\nYou must call DMSetUseNatural() before DMPlexDistribute().");
  }
  PetscCall(PetscLogEventEnd(DMPLEX_GlobalToNaturalBegin, dm, 0, 0, 0));
  PetscFunctionReturn(PETSC_SUCCESS);
}

/*@
  DMPlexGlobalToNaturalEnd - Rearranges a global `Vec` in the natural order.

  Collective on dm

  Input Parameters:
+ dm - The distributed `DMPLEX`
- gv - The global `Vec`

  Output Parameter:
. nv - The natural `Vec`

  Level: intermediate

  Note:
  The user must call `DMSetUseNatural`(dm, `PETSC_TRUE`) before `DMPlexDistribute()`.

 .seealso: [](chapter_unstructured), `DM`, `DMPLEX`, `Vec`, `DMPlexDistribute()`, `DMPlexDistributeField()`, `DMPlexNaturalToGlobalBegin()`, `DMPlexGlobalToNaturalBegin()`
 @*/
PetscErrorCode DMPlexGlobalToNaturalEnd(DM dm, Vec gv, Vec nv)
{
  const PetscScalar *inarray;
  PetscScalar       *outarray;
  PetscMPIInt        size;

  PetscFunctionBegin;
  PetscCall(PetscLogEventBegin(DMPLEX_GlobalToNaturalEnd, dm, 0, 0, 0));
  PetscCallMPI(MPI_Comm_size(PetscObjectComm((PetscObject)dm), &size));
  if (dm->sfNatural) {
    PetscCall(VecGetArrayRead(gv, &inarray));
    PetscCall(VecGetArray(nv, &outarray));
    PetscCall(PetscSFBcastEnd(dm->sfNatural, MPIU_SCALAR, (PetscScalar *)inarray, outarray, MPI_REPLACE));
    PetscCall(VecRestoreArrayRead(gv, &inarray));
    PetscCall(VecRestoreArray(nv, &outarray));
  } else if (size == 1) {
  } else {
    PetscCheck(!dm->useNatural, PetscObjectComm((PetscObject)dm), PETSC_ERR_PLIB, "DM global to natural SF not present.\nIf DMPlexDistribute() was called and a section was defined, report to petsc-maint@mcs.anl.gov.");
    SETERRQ(PetscObjectComm((PetscObject)dm), PETSC_ERR_ARG_WRONGSTATE, "DM global to natural SF was not created.\nYou must call DMSetUseNatural() before DMPlexDistribute().");
  }
  PetscCall(PetscLogEventEnd(DMPLEX_GlobalToNaturalEnd, dm, 0, 0, 0));
  PetscFunctionReturn(PETSC_SUCCESS);
}

/*@
  DMPlexNaturalToGlobalBegin - Rearranges a `Vec` in the natural order to the Global order.

  Collective on dm

  Input Parameters:
+ dm - The distributed `DMPLEX`
- nv - The natural `Vec`

  Output Parameters:
. gv - The global `Vec`

  Level: intermediate

  Note:
  The user must call `DMSetUseNatural`(dm, `PETSC_TRUE`) before `DMPlexDistribute()`.

.seealso: [](chapter_unstructured), `DM`, `DMPLEX`, `Vec`, `DMPlexDistribute()`, `DMPlexDistributeField()`, `DMPlexNaturalToGlobalBegin()`, `DMPlexGlobalToNaturalEnd()`
@*/
PetscErrorCode DMPlexNaturalToGlobalBegin(DM dm, Vec nv, Vec gv)
{
  const PetscScalar *inarray;
  PetscScalar       *outarray;
  PetscMPIInt        size;

  PetscFunctionBegin;
  PetscCall(PetscLogEventBegin(DMPLEX_NaturalToGlobalBegin, dm, 0, 0, 0));
  PetscCallMPI(MPI_Comm_size(PetscObjectComm((PetscObject)dm), &size));
  if (dm->sfNatural) {
    /* We only have access to the SF that goes from Global to Natural.
       Instead of inverting dm->sfNatural, we can call PetscSFReduceBegin/End with MPI_Op MPI_SUM.
       Here the SUM really does nothing since sfNatural is one to one, as long as gV is set to zero first. */
    PetscCall(VecZeroEntries(gv));
    PetscCall(VecGetArray(gv, &outarray));
    PetscCall(VecGetArrayRead(nv, &inarray));
    PetscCall(PetscSFReduceBegin(dm->sfNatural, MPIU_SCALAR, (PetscScalar *)inarray, outarray, MPI_SUM));
    PetscCall(VecRestoreArrayRead(nv, &inarray));
    PetscCall(VecRestoreArray(gv, &outarray));
  } else if (size == 1) {
    PetscCall(VecCopy(nv, gv));
  } else {
    PetscCheck(!dm->useNatural, PetscObjectComm((PetscObject)dm), PETSC_ERR_PLIB, "DM global to natural SF not present.\nIf DMPlexDistribute() was called and a section was defined, report to petsc-maint@mcs.anl.gov.");
    SETERRQ(PetscObjectComm((PetscObject)dm), PETSC_ERR_ARG_WRONGSTATE, "DM global to natural SF was not created.\nYou must call DMSetUseNatural() before DMPlexDistribute().");
  }
  PetscCall(PetscLogEventEnd(DMPLEX_NaturalToGlobalBegin, dm, 0, 0, 0));
  PetscFunctionReturn(PETSC_SUCCESS);
}

/*@
  DMPlexNaturalToGlobalEnd - Rearranges a `Vec` in the natural order to the Global order.

  Collective on dm

  Input Parameters:
+ dm - The distributed `DMPLEX`
- nv - The natural `Vec`

  Output Parameters:
. gv - The global `Vec`

  Level: intermediate

  Note:
  The user must call `DMSetUseNatural`(dm, `PETSC_TRUE`) before `DMPlexDistribute()`.

.seealso: [](chapter_unstructured), `DM`, `DMPLEX`, `Vec`, `DMPlexDistribute()`, `DMPlexDistributeField()`, `DMPlexNaturalToGlobalBegin()`, `DMPlexGlobalToNaturalBegin()`
 @*/
PetscErrorCode DMPlexNaturalToGlobalEnd(DM dm, Vec nv, Vec gv)
{
  const PetscScalar *inarray;
  PetscScalar       *outarray;
  PetscMPIInt        size;

  PetscFunctionBegin;
  PetscCall(PetscLogEventBegin(DMPLEX_NaturalToGlobalEnd, dm, 0, 0, 0));
  PetscCallMPI(MPI_Comm_size(PetscObjectComm((PetscObject)dm), &size));
  if (dm->sfNatural) {
    PetscCall(VecGetArrayRead(nv, &inarray));
    PetscCall(VecGetArray(gv, &outarray));
    PetscCall(PetscSFReduceEnd(dm->sfNatural, MPIU_SCALAR, (PetscScalar *)inarray, outarray, MPI_SUM));
    PetscCall(VecRestoreArrayRead(nv, &inarray));
    PetscCall(VecRestoreArray(gv, &outarray));
  } else if (size == 1) {
  } else {
    PetscCheck(!dm->useNatural, PetscObjectComm((PetscObject)dm), PETSC_ERR_PLIB, "DM global to natural SF not present.\nIf DMPlexDistribute() was called and a section was defined, report to petsc-maint@mcs.anl.gov.");
    SETERRQ(PetscObjectComm((PetscObject)dm), PETSC_ERR_ARG_WRONGSTATE, "DM global to natural SF was not created.\nYou must call DMSetUseNatural() before DMPlexDistribute().");
  }
  PetscCall(PetscLogEventEnd(DMPLEX_NaturalToGlobalEnd, dm, 0, 0, 0));
  PetscFunctionReturn(PETSC_SUCCESS);
}

/*@
  DMPlexCreateNaturalVector - Provide a `Vec` capable of holding the natural ordering and distribution.

  Collective on dm

  Input Parameter:
. dm - The distributed `DMPLEX`

  Output Parameter:
. nv - The natural `Vec`

  Level: intermediate

  Note:
  The user must call `DMSetUseNatural`(dm, `PETSC_TRUE`) before `DMPlexDistribute()`.

.seealso: [](chapter_unstructured), `DM`, `DMPLEX`, `Vec`, `DMPlexDistribute()`, `DMPlexNaturalToGlobalBegin()`, `DMPlexGlobalToNaturalBegin()`
 @*/
PetscErrorCode DMPlexCreateNaturalVector(DM dm, Vec *nv)
{
  PetscMPIInt size;

  PetscFunctionBegin;
  PetscCallMPI(MPI_Comm_size(PetscObjectComm((PetscObject)dm), &size));
  if (dm->sfNatural) {
    PetscInt nleaves, bs, maxbs;
    Vec      v;

    /*
      Setting the natural vector block size.
      We can't get it from a global vector because of constraints, and the block size in the local vector
      may be inconsistent across processes, typically when some local vectors have size 0, their block size is set to 1
    */
    PetscCall(DMGetLocalVector(dm, &v));
    PetscCall(VecGetBlockSize(v, &bs));
    PetscCallMPI(MPI_Allreduce(&bs, &maxbs, 1, MPIU_INT, MPI_MAX, PetscObjectComm((PetscObject)dm)));
    if (bs == 1 && maxbs > 1) bs = maxbs;
    PetscCall(DMRestoreLocalVector(dm, &v));

    PetscCall(PetscSFGetGraph(dm->sfNatural, NULL, &nleaves, NULL, NULL));
    PetscCall(VecCreate(PetscObjectComm((PetscObject)dm), nv));
    PetscCall(VecSetSizes(*nv, nleaves, PETSC_DETERMINE));
    PetscCall(VecSetBlockSize(*nv, bs));
    PetscCall(VecSetType(*nv, dm->vectype));
    PetscCall(VecSetDM(*nv, dm));
  } else if (size == 1) {
    PetscCall(DMCreateLocalVector(dm, nv));
  } else {
    PetscCheck(!dm->useNatural, PetscObjectComm((PetscObject)dm), PETSC_ERR_PLIB, "DM global to natural SF not present.\nIf DMPlexDistribute() was called and a section was defined, report to petsc-maint@mcs.anl.gov.");
    SETERRQ(PetscObjectComm((PetscObject)dm), PETSC_ERR_ARG_WRONGSTATE, "DM global to natural SF was not created.\nYou must call DMSetUseNatural() before DMPlexDistribute().");
  }
  PetscFunctionReturn(PETSC_SUCCESS);
}