# sparse_alltoall_test.f90 Source File

## Source Code

! Copyright (c) 2017 Jiaxing Qi <jiaxing.qi@uni-siegen.de>
!
! Redistribution and use in source and binary forms, with or without
! modification, are permitted provided that the following conditions are met:
!
! 1. Redistributions of source code must retain the above copyright notice, this
! list of conditions and the following disclaimer.
!
! 2. Redistributions in binary form must reproduce the above copyright notice,
! this list of conditions and the following disclaimer in the documentation
! and/or other materials provided with the distribution.
!
! THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
! AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
! IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
! DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
! FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
! DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
! SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
! CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
! OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
! OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
!mpi!nprocs = 4
program sparse_alltoall_test
use mpi
use tem_sparse_comm_module, only: tem_sparse_alltoall_int

implicit none

! Assume we have 4 procs: 0 - 1 - 2 - 3
! Each proc send data to their direct neighbors
! the data is a single integer whose value is the targeting proc, i.e.
! proc 0 sends value 1 to proc 1
! proc 1 sends value 0 to proc 0, value 2 to proc 2
! proc 2 sends value 1 to proc 1, value 3 to proc 3
! proc 3 sends value 2 to proc 2
! After communication, each proc should have the following data:
! proc 0: 0
! proc 1: 1 1
! proc 2: 2 2
! proc 3: 3

integer :: iError
integer :: myrank, nProcs
logical :: local_success, success
! integer :: rstat(MPI_STATUS_SIZE)

integer, allocatable :: targets(:)
integer, allocatable :: send_buffer(:)
integer, allocatable :: sources(:)
integer, allocatable :: recv_buffer(:)

call MPI_Init(iError)
call MPI_Comm_rank(MPI_COMM_WORLD, myrank, iError)
call MPI_COMM_SIZE(MPI_COMM_WORLD, nProcs, IERROR)

if ( myrank == 0 ) then
! has one neighbor
allocate( targets(1) )
allocate( send_buffer(1) )
targets(1)     = myrank + 1
send_buffer(1) = myrank + 1
else if ( myrank == (nProcs-1) ) then
! has one neighbor
allocate( targets(1) )
allocate( send_buffer(1) )
targets(1)     = myrank - 1
send_buffer(1) = myrank - 1
else
! has two neighbor
allocate( targets(2) )
allocate( send_buffer(2) )
targets(1)     = myrank - 1
targets(2)     = myrank + 1
send_buffer(1) = myrank - 1
send_buffer(2) = myrank + 1
end if

call tem_sparse_alltoall_int( targets, send_buffer, &
&                           sources, recv_buffer, MPI_COMM_WORLD)

if ( myrank == 0 .or. myrank == (nProcs-1) ) then
local_success = (recv_buffer(1) == myrank)
else
local_success = ((recv_buffer(1) == myrank) .and. (recv_buffer(2) == myrank))
end if

if ( .not. local_success ) then
write(*,*) "Rank: ", myrank, " sources: ", sources
write(*,*) "Rank: ", myrank, " recv_bu: ", recv_buffer
end if

call MPI_REDUCE(local_success, success, 1, MPI_LOGICAL, MPI_LAND, 0, MPI_COMM_world, IERROR)

if ( myrank == 0 ) then
if ( success ) then
write(*,*) "PASSED"
else
write(*,*) "FAILED"
end if
end if

call MPI_Finalize(iError)

end program sparse_alltoall_test