1: !    Description: A star forest is a simple tree with one root and zero or more leaves.
  2: !    Many common communication patterns can be expressed as updates of rootdata using leafdata and vice-versa.
  3: !     This example creates a star forest, communicates values using the graph  views the graph, then destroys it.
  4: !
  5: !     This is a copy of ex1.c but currently only tests the broadcast operation
  6: #include <petsc/finclude/petscvec.h>
  7: program main
  8:   use petscvec
  9:   implicit none

 11:   PetscErrorCode ierr
 12:   PetscInt i, nroots, nrootsalloc, nleaves, nleavesalloc, mine(6), stride
 13:   PetscSFNode remote(6)
 14:   PetscMPIInt rank, size
 15:   PetscSF sf
 16:   PetscInt rootdata(6), leafdata(6)

 18: ! used with PetscSFGetGraph()
 19:   PetscSFNode, pointer ::       gremote(:)
 20:   PetscInt, pointer ::          gmine(:)
 21:   PetscInt gnroots, gnleaves

 23:   PetscMPIInt niranks, nranks
 24:   PetscMPIInt, pointer ::       iranks(:), ranks(:)
 25:   PetscInt, pointer ::          ioffset(:), irootloc(:), roffset(:), rmine(:), rremote(:)

 27:   PetscCallA(PetscInitialize(ierr))
 28:   stride = 2
 29:   PetscCallMPIA(MPI_Comm_rank(PETSC_COMM_WORLD, rank, ierr))
 30:   PetscCallMPIA(MPI_Comm_size(PETSC_COMM_WORLD, size, ierr))

 32:   if (rank == 0) then
 33:     nroots = 3
 34:   else
 35:     nroots = 2
 36:   end if
 37:   nrootsalloc = nroots*stride
 38:   if (rank > 0) then
 39:     nleaves = 3
 40:   else
 41:     nleaves = 2
 42:   end if
 43:   nleavesalloc = nleaves*stride
 44:   if (stride > 1) then
 45:     do i = 1, nleaves
 46:       mine(i) = stride*(i - 1)
 47:     end do
 48:   end if

 50: ! Left periodic neighbor
 51:   remote(1)%rank = modulo(rank + size - 1, size)
 52:   remote(1)%index = 1*stride
 53: ! Right periodic neighbor
 54:   remote(2)%rank = modulo(rank + 1, size)
 55:   remote(2)%index = 0*stride
 56:   if (rank > 0) then !               All processes reference rank 0, index
 57:     remote(3)%rank = 0
 58:     remote(3)%index = 2*stride
 59:   end if

 61: !  Create a star forest for communication
 62:   PetscCallA(PetscSFCreate(PETSC_COMM_WORLD, sf, ierr))
 63:   PetscCallA(PetscSFSetFromOptions(sf, ierr))
 64:   PetscCallA(PetscSFSetGraph(sf, nrootsalloc, nleaves, mine, PETSC_COPY_VALUES, remote, PETSC_COPY_VALUES, ierr))
 65:   PetscCallA(PetscSFSetUp(sf, ierr))

 67: !   View graph, mostly useful for debugging purposes.
 68:   PetscCallA(PetscViewerPushFormat(PETSC_VIEWER_STDOUT_WORLD, PETSC_VIEWER_ASCII_INFO_DETAIL, ierr))
 69:   PetscCallA(PetscSFView(sf, PETSC_VIEWER_STDOUT_WORLD, ierr))
 70:   PetscCallA(PetscViewerPopFormat(PETSC_VIEWER_STDOUT_WORLD, ierr))

 72: !   Allocate space for send and receive buffers. This example communicates PetscInt, but other types, including
 73: !     * user-defined structures, could also be used.
 74: !     Set rootdata buffer to be broadcast
 75:   do i = 1, nrootsalloc
 76:     rootdata(i) = -1
 77:   end do
 78:   do i = 1, nroots
 79:     rootdata(1 + (i - 1)*stride) = 100*(rank + 1) + i - 1
 80:   end do

 82: !     Initialize local buffer, these values are never used.
 83:   do i = 1, nleavesalloc
 84:     leafdata(i) = -1
 85:   end do

 87: !     Broadcast entries from rootdata to leafdata. Computation or other communication can be performed between the begin and end calls.
 88:   PetscCallA(PetscSFBcastBegin(sf, MPIU_INTEGER, rootdata, leafdata, MPI_REPLACE, ierr))
 89:   PetscCallA(PetscSFBcastEnd(sf, MPIU_INTEGER, rootdata, leafdata, MPI_REPLACE, ierr))
 90:   PetscCallA(PetscViewerASCIIPrintf(PETSC_VIEWER_STDOUT_WORLD, '## Bcast Rootdata\n', ierr))
 91:   PetscCallA(PetscIntView(nrootsalloc, rootdata, PETSC_VIEWER_STDOUT_WORLD, ierr))
 92:   PetscCallA(PetscViewerASCIIPrintf(PETSC_VIEWER_STDOUT_WORLD, '## Bcast Leafdata\n', ierr))
 93:   PetscCallA(PetscIntView(nleavesalloc, leafdata, PETSC_VIEWER_STDOUT_WORLD, ierr))

 95: !     Reduce entries from leafdata to rootdata. Computation or other communication can be performed between the begin and end calls.
 96:   PetscCallA(PetscSFReduceBegin(sf, MPIU_INTEGER, leafdata, rootdata, MPI_SUM, ierr))
 97:   PetscCallA(PetscSFReduceEnd(sf, MPIU_INTEGER, leafdata, rootdata, MPI_SUM, ierr))
 98:   PetscCallA(PetscViewerASCIIPrintf(PETSC_VIEWER_STDOUT_WORLD, '## Reduce Leafdata\n', ierr))
 99:   PetscCallA(PetscIntView(nleavesalloc, leafdata, PETSC_VIEWER_STDOUT_WORLD, ierr))
100:   PetscCallA(PetscViewerASCIIPrintf(PETSC_VIEWER_STDOUT_WORLD, '## Reduce Rootdata\n', ierr))
101:   PetscCallA(PetscIntView(nrootsalloc, rootdata, PETSC_VIEWER_STDOUT_WORLD, ierr))

103:   PetscCallA(PetscSFGetGraph(sf, gnroots, gnleaves, gmine, gremote, ierr))
104:   PetscCheckA(gnleaves == nleaves, PETSC_COMM_WORLD, PETSC_ERR_PLIB, 'nleaves returned from PetscSFGetGraph() does not match that set with PetscSFSetGraph()')
105:   do i = 1, nleaves
106:     PetscCheckA(gmine(i) == mine(i), PETSC_COMM_WORLD, PETSC_ERR_PLIB, 'Root from PetscSFGetGraph() does not match that set with PetscSFSetGraph()')
107:   end do
108:   do i = 1, nleaves
109:     PetscCheckA(gremote(i)%index == remote(i)%index, PETSC_COMM_WORLD, PETSC_ERR_PLIB, 'Leaf from PetscSFGetGraph() does not match that set with PetscSFSetGraph()')
110:   end do
111:   PetscCallA(PetscSFRestoreGraph(sf, gnroots, gnleaves, gmine, gremote, ierr))

113: ! Test PetscSFGet{Leaf,Root}Ranks
114:   PetscCallA(PetscSFGetLeafRanks(sf, niranks, iranks, ioffset, irootloc, ierr))
115:   PetscCallA(PetscSFGetRootRanks(sf, nranks, ranks, roffset, rmine, rremote, ierr))

117: !    Clean storage for star forest.
118:   PetscCallA(PetscSFDestroy(sf, ierr))

120: !  Create a star forest with continuous leaves and hence no buffer
121:   PetscCallA(PetscSFCreate(PETSC_COMM_WORLD, sf, ierr))
122:   PetscCallA(PetscSFSetFromOptions(sf, ierr))
123:   PetscCallA(PetscSFSetGraph(sf, nrootsalloc, nleaves, PETSC_NULL_INTEGER_ARRAY, PETSC_COPY_VALUES, remote, PETSC_COPY_VALUES, ierr))
124:   PetscCallA(PetscSFSetUp(sf, ierr))

126: !   View graph, mostly useful for debugging purposes.
127:   PetscCallA(PetscViewerPushFormat(PETSC_VIEWER_STDOUT_WORLD, PETSC_VIEWER_ASCII_INFO_DETAIL, ierr))
128:   PetscCallA(PetscSFView(sf, PETSC_VIEWER_STDOUT_WORLD, ierr))
129:   PetscCallA(PetscViewerPopFormat(PETSC_VIEWER_STDOUT_WORLD, ierr))

131:   PetscCallA(PetscSFGetGraph(sf, gnroots, gnleaves, gmine, gremote, ierr))
132:   PetscCheckA(loc(gmine) == loc(PETSC_NULL_INTEGER), PETSC_COMM_WORLD, PETSC_ERR_PLIB, 'Leaves from PetscSFGetGraph() not null as expected')
133:   PetscCallA(PetscSFRestoreGraph(sf, gnroots, gnleaves, gmine, gremote, ierr))
134:   PetscCallA(PetscSFDestroy(sf, ierr))
135:   PetscCallA(PetscFinalize(ierr))
136: end

138: !/*TEST
139: !  build:
140: !    requires: defined(PETSC_HAVE_FORTRAN_TYPE_STAR)
141: !
142: !  test:
143: !    nsize: 3
144: !
145: !TEST*/