psblas3/base/internals/psi_adjcncy_fnd_owner.F90

!   
!                Parallel Sparse BLAS  version 3.5
!      (C) Copyright 2006-2018
!        Salvatore Filippone    
!        Alfredo Buttari      
!   
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!    modification, are permitted provided that the following conditions
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!         software without specific written permission.
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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(:), sdhd(:), rvhd(:), p2pstat(:,:)
  integer(psb_mpk_) :: prc, p2ptag, iret
  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., new_impl=.true.
  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

  if (new_impl) then
    !
    ! First simple minded version with auxiliary arrays
    ! dimensioned on NP.
    ! Could it be improved with a loop based on the maximum length
    ! of adj(:) ???
    !    
    Allocate(hidx(0:np),hsz(np),sdsz(0:np-1),rvsz(0:np-1),&
         & sdhd(0:np-1), rvhd(0:np-1), p2pstat(mpi_status_size,0:np-1),&
         & stat=info)
    sdhd(:) = mpi_request_null
    rvhd(:) = mpi_request_null
    !
    ! 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(max(hsize,nidx*nadj)),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 i = 0, np-1
      if (rvsz(i)>0) then
        ! write(0,*) me, ' First receive from ',i,rvsz(i)
        prc = psb_get_rank(ictxt,i)        
        p2ptag = psb_long_swap_tag
        !write(0,*) me, ' Posting first receive from ',i,rvsz(i),prc           
        call mpi_irecv(rmtidx(hidx(i)+1),rvsz(i),&
             & psb_mpi_lpk_,prc,&
             & p2ptag, icomm,rvhd(i),iret)
      end if
    end do
    do j=1, nadj
      if (nidx > 0) then
        !call psb_snd(ictxt,idx(1:nidx),adj(j))
        prc = psb_get_rank(ictxt,adj(j))        
        p2ptag = psb_long_swap_tag
        !write(0,*) me, ' First send to ',adj(j),nidx, prc
        call mpi_send(idx,nidx,&
             & psb_mpi_lpk_,prc,&
             & p2ptag, icomm,iret)
      end if
    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
    call mpi_waitall(np,rvhd,p2pstat,iret)
    
    !
    ! 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
    !
    ! At this point we can reuse lclidx to receive messages
    !
    rvhd(:) = mpi_request_null
    do j=1, nadj
      !write(0,*) me, ' First send to ',adj(j),nidx
      if (nidx > 0) then
        !call psb_snd(ictxt,idx(1:nidx),adj(j))
        prc = psb_get_rank(ictxt,adj(j))        
        p2ptag = psb_int_swap_tag
        !write(0,*) me, ' Posting second receive from ',adj(j),nidx, prc
        call mpi_irecv(lclidx((j-1)*nidx+1),nidx, &
             & psb_mpi_ipk_,prc,&
             & p2ptag, icomm,rvhd(j),iret)
      end if
    end do
    
    !
    ! Fourth, send data back; 
    !
    do i = 0, np-1
      if (rvsz(i)>0) then
        !call psb_snd(ictxt,tproc(hidx(i)+1:hidx(i)+rvsz(i)),i)
        prc = psb_get_rank(ictxt,i)        
        p2ptag = psb_int_swap_tag
        !write(0,*) me, ' Second send to ',i,rvsz(i), prc
        call mpi_send(tproc(hidx(i)+1),rvsz(i),&
             & psb_mpi_ipk_,prc,&
             & p2ptag, icomm,iret)
      end if
    end do
    !
    ! Fifth: receive and combine. MAX works because default
    ! answer is -1. 
    !
    call mpi_waitall(np,rvhd,p2pstat,iret)    
    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), lclidx((j-1)*nidx+1:(j-1)*nidx+nidx))
    end do

  else
    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
  end if
  call psb_erractionrestore(err_act)
  return

9999 call psb_error_handler(ictxt,err_act)

  return

end subroutine psi_adjcncy_fnd_owner