psblas3/base/internals/psi_adjcncy_fnd_owner.F90

!   
!                Parallel Sparse BLAS  version 3.5
!      (C) Copyright 2006-2018
!        Salvatore Filippone    
!        Alfredo Buttari      
!   
!    Redistribution and use in source and binary forms, with or without
!    modification, are permitted provided that the following conditions
!    are met:
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!      2. Redistributions in binary form must reproduce the above copyright
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!         software without specific written permission.
!   
!    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
!    ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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!   
!   
!
! File: psi_fnd_owner.f90
!
! Subroutine: psi_fnd_owner
!   Figure out who owns  global indices. 
! 
! Arguments: 
! 
subroutine psi_adjcncy_fnd_owner(idx,iprc,adj,idxmap,info)
  use psb_serial_mod
  use psb_const_mod
  use psb_error_mod
  use psb_penv_mod
  use psb_realloc_mod
  use psb_indx_map_mod, psb_protect_name => psi_adjcncy_fnd_owner
#ifdef MPI_MOD
  use mpi
#endif

  implicit none 
#ifdef MPI_H
  include 'mpif.h'
#endif
  integer(psb_lpk_), intent(in)   :: idx(:)
  integer(psb_ipk_), allocatable, intent(out) :: iprc(:)
  integer(psb_ipk_), intent(in)   :: adj(:)
  class(psb_indx_map), intent(in) :: idxmap
  integer(psb_ipk_), intent(out)  :: info


  integer(psb_lpk_), allocatable :: rmtidx(:)
  integer(psb_ipk_), allocatable :: tproc(:), lclidx(:)
  integer(psb_mpk_), allocatable :: hsz(:),hidx(:), &
       & sdsz(:), rvsz(:)
  integer(psb_mpk_) :: icomm, minfo, iictxt
  integer(psb_ipk_) :: i,n_row,n_col,err_act,hsize,ip,isz,j, k,&
       & last_ih, last_j, nidx, nrecv, nadj
  integer(psb_lpk_) :: mglob, ih
  integer(psb_ipk_) :: ictxt,np,me
  logical, parameter  :: gettime=.false.
  real(psb_dpk_)      :: t0, t1, t2, t3, t4, tamx, tidx
  character(len=20)   :: name

  info = psb_success_
  name = 'psi_adjcncy_fnd_owner'
  call psb_erractionsave(err_act)

  ictxt   = idxmap%get_ctxt()
  icomm   = idxmap%get_mpic()
  mglob   = idxmap%get_gr()
  n_row   = idxmap%get_lr()
  n_col   = idxmap%get_lc()
  iictxt = ictxt 

  call psb_info(ictxt, me, np)

  if (np == -1) then
    info = psb_err_context_error_
    call psb_errpush(info,name)
    goto 9999
  endif

  if (.not.(idxmap%is_valid())) then 
    call psb_errpush(psb_err_from_subroutine_,name,a_err='invalid idxmap')
    goto 9999      
  end if

  if (gettime) then 
    t0 = psb_wtime()
  end if

  nadj = size(adj)
  nidx = size(idx)
  call psb_realloc(nidx,iprc,info)
  if (info /= psb_success_) then 
    call psb_errpush(psb_err_from_subroutine_,name,a_err='psb_realloc')
    goto 9999      
  end if
  iprc = -1
  ! write(0,*) me,name,' Going through ',nidx,nadj

  Allocate(hidx(0:np),hsz(np),&
       & sdsz(0:np-1),rvsz(0:np-1),stat=info)
  !
  ! First, send sizes according to adjcncy list
  !
  sdsz = 0 
  do j=1, nadj
    sdsz(adj(j)) = nidx
  end do
  !write(0,*)me,' Check on sizes into a2a:',adj(:),nadj,':',sdsz(:)
  
  call mpi_alltoall(sdsz,1,psb_mpi_mpk_,&
       & rvsz,1,psb_mpi_mpk_,icomm,minfo)
  hidx(0) = 0
  do i=0, np-1
    hidx(i+1) = hidx(i) + rvsz(i)
  end do
  hsize = hidx(np)
  ! write(0,*)me,' Check on sizes from a2a:',hsize,rvsz(:)
  !
  ! Second, allocate buffers and exchange data
  !
  Allocate(rmtidx(hsize),lclidx(hsize),tproc(max(hsize,nidx)),stat=info)
  
  if (info /= psb_success_) then 
    call psb_errpush(psb_err_from_subroutine_,name,a_err='Allocate')
    goto 9999      
  end if
  do j=1, nadj
    !write(0,*) me, ' First send to ',adj(j),nidx
    if (nidx > 0) call psb_snd(ictxt,idx(1:nidx),adj(j))
  end do
  do i = 0, np-1
    if (rvsz(i)>0) then
      ! write(0,*) me, ' First receive from ',i,rvsz(i)           
      call psb_rcv(ictxt,rmtidx(hidx(i)+1:hidx(i)+rvsz(i)),i)
    end if
  end do
  
  !
  ! Third, compute local answers
  !
  call idxmap%g2l(rmtidx(1:hsize),lclidx(1:hsize),info,owned=.true.)
  do i=1, hsize
    tproc(i) = -1
    if ((0 < lclidx(i)).and. (lclidx(i) <= n_row)) tproc(i) = me
  end do
      
  !
  ! Fourth, send data back; 
  !
  do i = 0, np-1
    if (rvsz(i)>0) then
      !write(0,*) me, ' Second send to ',i,rvsz(i)
      call psb_snd(ictxt,tproc(hidx(i)+1:hidx(i)+rvsz(i)),i)
    end if
  end do
  !
  ! Fifth: receive and combine. MAX works because default
  ! answer is -1. Reuse tproc
  !
  do j = 1, nadj
    !write(0,*) me, ' Second receive from ',adj(j), nidx          
    if (nidx > 0) call psb_rcv(ictxt,tproc(1:nidx),adj(j))
    iprc(1:nidx) = max(iprc(1:nidx), tproc(1:nidx))
  end do
  
  call psb_erractionrestore(err_act)
  return

9999 call psb_error_handler(ictxt,err_act)

  return

end subroutine psi_adjcncy_fnd_owner