Actual source code: sliced.c
petsc-3.10.5 2019-03-28
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      1:  #include <petscdmsliced.h>
      2:  #include <petscmat.h>
      3:  #include <petsc/private/dmimpl.h>

      5: /* CSR storage of the nonzero structure of a bs*bs matrix */
      6: typedef struct {
      7:   PetscInt bs,nz,*i,*j;
      8: } DMSlicedBlockFills;

     10: typedef struct  {
     11:   PetscInt           bs,n,N,Nghosts,*ghosts;
     12:   PetscInt           d_nz,o_nz,*d_nnz,*o_nnz;
     13:   DMSlicedBlockFills *dfill,*ofill;
     14: } DM_Sliced;

     16: PetscErrorCode  DMCreateMatrix_Sliced(DM dm, Mat *J)
     17: {
     18:   PetscErrorCode         ierr;
     19:   PetscInt               *globals,*sd_nnz,*so_nnz,rstart,bs,i;
     20:   ISLocalToGlobalMapping lmap;
     21:   void                   (*aij)(void) = NULL;
     22:   DM_Sliced              *slice = (DM_Sliced*)dm->data;

     25:   bs   = slice->bs;
     26:   MatCreate(PetscObjectComm((PetscObject)dm),J);
     27:   MatSetSizes(*J,slice->n*bs,slice->n*bs,PETSC_DETERMINE,PETSC_DETERMINE);
     28:   MatSetBlockSize(*J,bs);
     29:   MatSetType(*J,dm->mattype);
     30:   MatSeqBAIJSetPreallocation(*J,bs,slice->d_nz,slice->d_nnz);
     31:   MatMPIBAIJSetPreallocation(*J,bs,slice->d_nz,slice->d_nnz,slice->o_nz,slice->o_nnz);
     32:   /* In general, we have to do extra work to preallocate for scalar (AIJ) matrices so we check whether it will do any
     33:   * good before going on with it. */
     34:   PetscObjectQueryFunction((PetscObject)*J,"MatMPIAIJSetPreallocation_C",&aij);
     35:   if (!aij) {
     36:     PetscObjectQueryFunction((PetscObject)*J,"MatSeqAIJSetPreallocation_C",&aij);
     37:   }
     38:   if (aij) {
     39:     if (bs == 1) {
     40:       MatSeqAIJSetPreallocation(*J,slice->d_nz,slice->d_nnz);
     41:       MatMPIAIJSetPreallocation(*J,slice->d_nz,slice->d_nnz,slice->o_nz,slice->o_nnz);
     42:     } else if (!slice->d_nnz) {
     43:       MatSeqAIJSetPreallocation(*J,slice->d_nz*bs,NULL);
     44:       MatMPIAIJSetPreallocation(*J,slice->d_nz*bs,NULL,slice->o_nz*bs,NULL);
     45:     } else {
     46:       /* The user has provided preallocation per block-row, convert it to per scalar-row respecting DMSlicedSetBlockFills() if applicable */
     47:       PetscMalloc2(slice->n*bs,&sd_nnz,(!!slice->o_nnz)*slice->n*bs,&so_nnz);
     48:       for (i=0; i<slice->n*bs; i++) {
     49:         sd_nnz[i] = (slice->d_nnz[i/bs]-1) * (slice->ofill ? slice->ofill->i[i%bs+1]-slice->ofill->i[i%bs] : bs)
     50:                                            + (slice->dfill ? slice->dfill->i[i%bs+1]-slice->dfill->i[i%bs] : bs);
     51:         if (so_nnz) {
     52:           so_nnz[i] = slice->o_nnz[i/bs] * (slice->ofill ? slice->ofill->i[i%bs+1]-slice->ofill->i[i%bs] : bs);
     53:         }
     54:       }
     55:       MatSeqAIJSetPreallocation(*J,slice->d_nz*bs,sd_nnz);
     56:       MatMPIAIJSetPreallocation(*J,slice->d_nz*bs,sd_nnz,slice->o_nz*bs,so_nnz);
     57:       PetscFree2(sd_nnz,so_nnz);
     58:     }
     59:   }

     61:   /* Set up the local to global map.  For the scalar map, we have to translate to entry-wise indexing instead of block-wise. */
     62:   PetscMalloc1(slice->n+slice->Nghosts,&globals);
     63:   MatGetOwnershipRange(*J,&rstart,NULL);
     64:   for (i=0; i<slice->n; i++) globals[i] = rstart/bs + i;

     66:   for (i=0; i<slice->Nghosts; i++) {
     67:     globals[slice->n+i] = slice->ghosts[i];
     68:   }
     69:   ISLocalToGlobalMappingCreate(PETSC_COMM_SELF,bs,slice->n+slice->Nghosts,globals,PETSC_OWN_POINTER,&lmap);
     70:   MatSetLocalToGlobalMapping(*J,lmap,lmap);
     71:   ISLocalToGlobalMappingDestroy(&lmap);
     72:   return(0);
     73: }

     75: /*@C
     76:     DMSlicedSetGhosts - Sets the global indices of other processes elements that will
     77:       be ghosts on this process

     79:     Not Collective

     81:     Input Parameters:
     82: +    slice - the DM object
     83: .    bs - block size
     84: .    nlocal - number of local (owned, non-ghost) blocks
     85: .    Nghosts - number of ghost blocks on this process
     86: -    ghosts - global indices of each ghost block

     88:     Level: advanced

     90: .seealso DMDestroy(), DMCreateGlobalVector()

     92: @*/
     93: PetscErrorCode  DMSlicedSetGhosts(DM dm,PetscInt bs,PetscInt nlocal,PetscInt Nghosts,const PetscInt ghosts[])
     94: {
     96:   DM_Sliced      *slice = (DM_Sliced*)dm->data;

    100:   PetscFree(slice->ghosts);
    101:   PetscMalloc1(Nghosts,&slice->ghosts);
    102:   PetscMemcpy(slice->ghosts,ghosts,Nghosts*sizeof(PetscInt));
    103:   slice->bs      = bs;
    104:   slice->n       = nlocal;
    105:   slice->Nghosts = Nghosts;
    106:   return(0);
    107: }

    109: /*@C
    110:     DMSlicedSetPreallocation - sets the matrix memory preallocation for matrices computed by DMSliced

    112:     Not Collective

    114:     Input Parameters:
    115: +    slice - the DM object
    116: .    d_nz  - number of block nonzeros per block row in diagonal portion of local
    117:            submatrix  (same for all local rows)
    118: .    d_nnz - array containing the number of block nonzeros in the various block rows
    119:            of the in diagonal portion of the local (possibly different for each block
    120:            row) or NULL.
    121: .    o_nz  - number of block nonzeros per block row in the off-diagonal portion of local
    122:            submatrix (same for all local rows).
    123: -    o_nnz - array containing the number of nonzeros in the various block rows of the
    124:            off-diagonal portion of the local submatrix (possibly different for
    125:            each block row) or NULL.

    127:     Notes:
    128:     See MatMPIBAIJSetPreallocation() for more details on preallocation.  If a scalar matrix (AIJ) is
    129:     obtained with DMSlicedGetMatrix(), the correct preallocation will be set, respecting DMSlicedSetBlockFills().

    131:     Level: advanced

    133: .seealso DMDestroy(), DMCreateGlobalVector(), MatMPIAIJSetPreallocation(),
    134:          MatMPIBAIJSetPreallocation(), DMSlicedGetMatrix(), DMSlicedSetBlockFills()

    136: @*/
    137: PetscErrorCode  DMSlicedSetPreallocation(DM dm,PetscInt d_nz,const PetscInt d_nnz[],PetscInt o_nz,const PetscInt o_nnz[])
    138: {
    139:   DM_Sliced *slice = (DM_Sliced*)dm->data;

    143:   slice->d_nz  = d_nz;
    144:   slice->d_nnz = (PetscInt*)d_nnz;
    145:   slice->o_nz  = o_nz;
    146:   slice->o_nnz = (PetscInt*)o_nnz;
    147:   return(0);
    148: }

    150: static PetscErrorCode DMSlicedSetBlockFills_Private(PetscInt bs,const PetscInt *fill,DMSlicedBlockFills **inf)
    151: {
    152:   PetscErrorCode     ierr;
    153:   PetscInt           i,j,nz,*fi,*fj;
    154:   DMSlicedBlockFills *f;

    158:   if (*inf) {PetscFree3(*inf,(*inf)->i,(*inf)->j);}
    159:   if (!fill) return(0);
    160:   for (i=0,nz=0; i<bs*bs; i++) if (fill[i]) nz++;
    161:   PetscMalloc3(1,&f,bs+1,&fi,nz,&fj);
    162:   f->bs = bs;
    163:   f->nz = nz;
    164:   f->i  = fi;
    165:   f->j  = fj;
    166:   for (i=0,nz=0; i<bs; i++) {
    167:     fi[i] = nz;
    168:     for (j=0; j<bs; j++) if (fill[i*bs+j]) fj[nz++] = j;
    169:   }
    170:   fi[i] = nz;
    171:   *inf  = f;
    172:   return(0);
    173: }

    175: /*@C
    176:     DMSlicedSetBlockFills - Sets the fill pattern in each block for a multi-component problem
    177:     of the matrix returned by DMSlicedGetMatrix().

    179:     Logically Collective on DM

    181:     Input Parameter:
    182: +   sliced - the DM object
    183: .   dfill - the fill pattern in the diagonal block (may be NULL, means use dense block)
    184: -   ofill - the fill pattern in the off-diagonal blocks

    186:     Notes:
    187:     This only makes sense for multicomponent problems using scalar matrix formats (AIJ).
    188:     See DMDASetBlockFills() for example usage.

    190:     Level: advanced

    192: .seealso DMSlicedGetMatrix(), DMDASetBlockFills()
    193: @*/
    194: PetscErrorCode  DMSlicedSetBlockFills(DM dm,const PetscInt *dfill,const PetscInt *ofill)
    195: {
    196:   DM_Sliced      *slice = (DM_Sliced*)dm->data;

    201:   DMSlicedSetBlockFills_Private(slice->bs,dfill,&slice->dfill);
    202:   DMSlicedSetBlockFills_Private(slice->bs,ofill,&slice->ofill);
    203:   return(0);
    204: }

    206: static PetscErrorCode  DMDestroy_Sliced(DM dm)
    207: {
    209:   DM_Sliced      *slice = (DM_Sliced*)dm->data;

    212:   PetscFree(slice->ghosts);
    213:   if (slice->dfill) {PetscFree3(slice->dfill,slice->dfill->i,slice->dfill->j);}
    214:   if (slice->ofill) {PetscFree3(slice->ofill,slice->ofill->i,slice->ofill->j);}
    215:   /* This was originally freed in DMDestroy(), but that prevents reference counting of backend objects */
    216:   PetscFree(slice);
    217:   return(0);
    218: }

    220: static PetscErrorCode  DMCreateGlobalVector_Sliced(DM dm,Vec *gvec)
    221: {
    223:   DM_Sliced      *slice = (DM_Sliced*)dm->data;

    228:   *gvec = 0;
    229:   VecCreateGhostBlock(PetscObjectComm((PetscObject)dm),slice->bs,slice->n*slice->bs,PETSC_DETERMINE,slice->Nghosts,slice->ghosts,gvec);
    230:   VecSetDM(*gvec,dm);
    231:   return(0);
    232: }

    234: static PetscErrorCode  DMGlobalToLocalBegin_Sliced(DM da,Vec g,InsertMode mode,Vec l)
    235: {
    237:   PetscBool      flg;

    240:   VecGhostIsLocalForm(g,l,&flg);
    241:   if (!flg) SETERRQ(PetscObjectComm((PetscObject)da),PETSC_ERR_ARG_WRONG,"Local vector is not local form of global vector");
    242:   VecGhostUpdateEnd(g,mode,SCATTER_FORWARD);
    243:   VecGhostUpdateBegin(g,mode,SCATTER_FORWARD);
    244:   return(0);
    245: }

    247: static PetscErrorCode  DMGlobalToLocalEnd_Sliced(DM da,Vec g,InsertMode mode,Vec l)
    248: {
    250:   PetscBool      flg;

    253:   VecGhostIsLocalForm(g,l,&flg);
    254:   if (!flg) SETERRQ(PetscObjectComm((PetscObject)da),PETSC_ERR_ARG_WRONG,"Local vector is not local form of global vector");
    255:   VecGhostUpdateEnd(g,mode,SCATTER_FORWARD);
    256:   return(0);
    257: }

    259: /*MC
    260:    DMSLICED = "sliced" - A DM object that is used to manage data for a general graph. Uses VecCreateGhost() ghosted vectors for storing the fields

    262:    See DMCreateSliced() for details.

    264:   Level: intermediate

    266: .seealso: DMType, DMCOMPOSITE, DMCreateSliced(), DMCreate()
    267: M*/

    269: PETSC_EXTERN PetscErrorCode DMCreate_Sliced(DM p)
    270: {
    272:   DM_Sliced      *slice;

    275:   PetscNewLog(p,&slice);
    276:   p->data = slice;

    278:   PetscObjectChangeTypeName((PetscObject)p,DMSLICED);

    280:   p->ops->createglobalvector = DMCreateGlobalVector_Sliced;
    281:   p->ops->creatematrix       = DMCreateMatrix_Sliced;
    282:   p->ops->globaltolocalbegin = DMGlobalToLocalBegin_Sliced;
    283:   p->ops->globaltolocalend   = DMGlobalToLocalEnd_Sliced;
    284:   p->ops->destroy            = DMDestroy_Sliced;
    285:   return(0);
    286: }

    288: /*@C
    289:     DMSlicedCreate - Creates a DM object, used to manage data for a unstructured problem

    291:     Collective on MPI_Comm

    293:     Input Parameter:
    294: +   comm - the processors that will share the global vector
    295: .   bs - the block size
    296: .   nlocal - number of vector entries on this process
    297: .   Nghosts - number of ghost points needed on this process
    298: .   ghosts - global indices of all ghost points for this process
    299: .   d_nnz - matrix preallocation information representing coupling within this process
    300: -   o_nnz - matrix preallocation information representing coupling between this process and other processes

    302:     Output Parameters:
    303: .   slice - the slice object

    305:     Notes:
    306:         This DM does not support DMCreateLocalVector(), DMGlobalToLocalBegin(), and DMGlobalToLocalEnd() instead one directly uses
    307:         VecGhostGetLocalForm() and VecGhostRestoreLocalForm() to access the local representation and VecGhostUpdateBegin() and VecGhostUpdateEnd() to update
    308:         the ghost points.

    310:         One can use DMGlobalToLocalBegin(), and DMGlobalToLocalEnd() instead of VecGhostUpdateBegin() and VecGhostUpdateEnd().

    312:     Level: advanced

    314: .seealso DMDestroy(), DMCreateGlobalVector(), DMSetType(), DMSLICED, DMSlicedSetGhosts(), DMSlicedSetPreallocation(), VecGhostUpdateBegin(), VecGhostUpdateEnd(),
    315:          VecGhostGetLocalForm(), VecGhostRestoreLocalForm()

    317: @*/
    318: PetscErrorCode  DMSlicedCreate(MPI_Comm comm,PetscInt bs,PetscInt nlocal,PetscInt Nghosts,const PetscInt ghosts[], const PetscInt d_nnz[],const PetscInt o_nnz[],DM *dm)
    319: {

    324:   DMCreate(comm,dm);
    325:   DMSetType(*dm,DMSLICED);
    326:   DMSlicedSetGhosts(*dm,bs,nlocal,Nghosts,ghosts);
    327:   if (d_nnz) {
    328:     DMSlicedSetPreallocation(*dm,0, d_nnz,0,o_nnz);
    329:   }
    330:   return(0);
    331: }