source: palm/trunk/SOURCE/pmc_handle_communicator_mod.f90 @ 4697

!> @file pmc_handle_communicator_mod.f90
!--------------------------------------------------------------------------------------------------!
! This file is part of the PALM model system.
!
! PALM is free software: you can redistribute it and/or modify it under the terms of the GNU General
! Public License as published by the Free Software Foundation, either version 3 of the License, or
! (at your option) any later version.
!
! PALM is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the
! implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
! Public License for more details.
!
! You should have received a copy of the GNU General Public License along with PALM. If not, see
! <http://www.gnu.org/licenses/>.
!
! Copyright 1997-2020 Leibniz Universitaet Hannover
!--------------------------------------------------------------------------------------------------!
!
!
! Current revisions:
! -----------------
!
!
! Former revisions:
! -----------------
! $Id: pmc_handle_communicator_mod.f90 4650 2020-08-25 14:35:50Z suehring $
! bugfix for r4649
!
! 4649 2020-08-25 12:11:17Z raasch
! File re-formatted to follow the PALM coding standard
!
!
! 4629 2020-07-29 09:37:56Z raasch
! Support for MPI Fortran77 interface (mpif.h) removed
!
! 4360 2020-01-07 11:25:50Z suehring
! Corrected "Former revisions" section
!
! 3888 2019-04-12 09:18:10Z hellstea
! Missing MPI_BCAST of anterpolation_buffer_width added.
!
! 3885 2019-04-11 11:29:34Z kanani
! Changes related to global restructuring of location messages and introduction of additional debug
! messages
!
! 3819 2019-03-27 11:01:36Z hellstea
! Adjustable anterpolation buffer introduced on all nest boundaries, it is controlled by the new
! nesting_parameters parameter anterpolation_buffer_width.
!
! 3655 2019-01-07 16:51:22Z knoop
! nestpar renamed to nesting_parameters
!
! 1762 2016-02-25 12:31:13Z hellstea
! Initial revision by K. Ketelsen
!
! Description:
! ------------
! Handle MPI communicator in PALM model coupler
!--------------------------------------------------------------------------------------------------!
 MODULE PMC_handle_communicator
#if defined( __parallel )
    USE kinds

    USE MPI

    USE pmc_general,                                                                               &
        ONLY: pmc_max_models,                                                                      &
              pmc_status_error,                                                                    &
              pmc_status_ok


    USE control_parameters,                                                                        &
        ONLY: message_string

    IMPLICIT NONE

!
!-- ATTENTION: Do not change the order of variable declarations in the following TYPE definition,
!-- because the order must follow the order in which the layout data is given in the NAMELIST file.
    TYPE pmc_layout

       CHARACTER(LEN=32) ::  name  !<

       INTEGER ::  id            !<
       INTEGER ::  parent_id     !<
       INTEGER ::  npe_total     !<

       REAL(wp) ::  lower_left_x  !<
       REAL(wp) ::  lower_left_y  !<

    END TYPE pmc_layout

    PUBLIC  pmc_status_ok, pmc_status_error  !<

    INTEGER, PARAMETER, PUBLIC ::  pmc_error_npes        = 1  !< illegal number of processes
    INTEGER, PARAMETER, PUBLIC ::  pmc_namelist_error    = 2  !< error(s) in nesting_parameters namelist
    INTEGER, PARAMETER, PUBLIC ::  pmc_no_namelist_found = 3  !< no couple layout namelist found

    INTEGER ::  m_my_cpl_id   !< coupler id of this model
    INTEGER ::  m_ncpl        !< number of couplers given in nesting_parameters namelist
    INTEGER ::  m_parent_id   !< coupler id of parent of this model
    INTEGER ::  m_world_comm  !< global nesting communicator

    TYPE(pmc_layout), PUBLIC, DIMENSION(pmc_max_models) ::  m_couplers  !< information of all couplers

    INTEGER, PUBLIC ::  m_model_comm          !< communicator of this model
    INTEGER, PUBLIC ::  m_model_npes          !<
    INTEGER, PUBLIC ::  m_model_rank          !<
    INTEGER, PUBLIC ::  m_to_parent_comm      !< communicator to the parent
    INTEGER, PUBLIC ::  m_world_rank          !<
    INTEGER         ::  m_parent_remote_size  !< number of processes in the parent model
    INTEGER         ::  m_world_npes          !<
    INTEGER         ::  peer_comm             !< peer_communicator for inter communicators

    INTEGER, DIMENSION(pmc_max_models), PUBLIC ::  m_to_child_comm   !< communicator to the child(ren)
    INTEGER, DIMENSION(:), POINTER, PUBLIC ::  pmc_parent_for_child  !<


    INTERFACE pmc_get_model_info
       MODULE PROCEDURE pmc_get_model_info
    END INTERFACE pmc_get_model_info

    INTERFACE pmc_is_rootmodel
       MODULE PROCEDURE pmc_is_rootmodel
    END INTERFACE pmc_is_rootmodel

    PUBLIC pmc_get_model_info, pmc_init_model, pmc_is_rootmodel   !<



 CONTAINS


!--------------------------------------------------------------------------------------------------!
! Description:
! ------------
!> @Todo: Missing subroutine description.
!--------------------------------------------------------------------------------------------------!
 SUBROUTINE pmc_init_model( comm, nesting_datatransfer_mode, nesting_mode,                         &
                            anterpolation_buffer_width, pmc_status )

    USE control_parameters,                                                                        &
        ONLY:  message_string

    USE pegrid,                                                                                    &
        ONLY:  myid

      IMPLICIT NONE

    CHARACTER(LEN=7), INTENT(INOUT) ::  nesting_datatransfer_mode  !<
    CHARACTER(LEN=8), INTENT(INOUT) ::  nesting_mode               !<

    INTEGER, INTENT(INOUT) ::  anterpolation_buffer_width  !< Boundary buffer width for anterpolation
    INTEGER, INTENT(INOUT) ::  comm                        !<
    INTEGER, INTENT(INOUT) ::  pmc_status                  !<

    INTEGER ::  childcount     !<
    INTEGER ::  i              !<
    INTEGER ::  ierr           !<
    INTEGER ::  istat          !<
    INTEGER ::  m_my_cpl_rank  !<
    INTEGER ::  tag            !<

    INTEGER, DIMENSION(pmc_max_models)   ::  activeparent  !< I am active parent for this child ID
    INTEGER, DIMENSION(pmc_max_models+1) ::  start_pe      !<

    pmc_status   = pmc_status_ok
    comm         = -1
    m_world_comm = MPI_COMM_WORLD
    m_my_cpl_id  = -1
    childcount   =  0
    activeparent = -1
    start_pe(:)  =  0

    CALL MPI_COMM_RANK( MPI_COMM_WORLD, m_world_rank, istat )
    CALL MPI_COMM_SIZE( MPI_COMM_WORLD, m_world_npes, istat )
!
!-- Only process 0 of root model reads
    IF ( m_world_rank == 0 )  THEN

       CALL read_coupling_layout( nesting_datatransfer_mode, nesting_mode,                         &
                                  anterpolation_buffer_width, pmc_status )

       IF ( pmc_status /= pmc_no_namelist_found  .AND.                                             &
            pmc_status /= pmc_namelist_error )                                                     &
       THEN
!
!--       Calculate start PE of every model
          start_pe(1) = 0
          DO  i = 2, m_ncpl+1
             start_pe(i) = start_pe(i-1) + m_couplers(i-1)%npe_total
          ENDDO

!
!--       The sum of numbers of processes requested by all the domains must be equal to the total
!--       number of processes of the run
          IF ( start_pe(m_ncpl+1) /= m_world_npes )  THEN
             WRITE( message_string, '(2A,I6,2A,I6,A)' )                                            &
                                                'nesting-setup requires different number of ',     &
                                                'MPI procs (', start_pe(m_ncpl+1), ') than ',      &
                                                'provided (', m_world_npes,')'
             CALL message( 'pmc_init_model', 'PA0229', 3, 2, 0, 6, 0 )
          ENDIF

       ENDIF

    ENDIF
!
!-- Broadcast the read status. This synchronises all other processes with process 0 of the root
!-- model. Without synchronisation, they would not behave in the correct way (e.g. they would not
!-- return in case of a missing NAMELIST).
    CALL MPI_BCAST( pmc_status, 1, MPI_INTEGER, 0, MPI_COMM_WORLD, istat )

    IF ( pmc_status == pmc_no_namelist_found )  THEN
!
!--    Not a nested run; return the MPI_WORLD communicator
       comm = MPI_COMM_WORLD
       RETURN

    ELSEIF ( pmc_status == pmc_namelist_error )  THEN
!
!--    Only the root model gives the error message. Others are aborted by the message-routine with
!--    MPI_ABORT. Must be done this way since myid and comm2d have not yet been assigned at this
!--    point.
       IF ( m_world_rank == 0 )  THEN
          message_string = 'errors in \$nesting_parameters'
          CALL message( 'pmc_init_model', 'PA0223', 3, 2, 0, 6, 0 )
       ENDIF

    ENDIF

    CALL MPI_BCAST( m_ncpl,          1, MPI_INTEGER, 0, MPI_COMM_WORLD, istat )
    CALL MPI_BCAST( start_pe, m_ncpl+1, MPI_INTEGER, 0, MPI_COMM_WORLD, istat )
!
!-- Broadcast coupling layout
    DO  i = 1, m_ncpl
       CALL MPI_BCAST( m_couplers(i)%name, LEN( m_couplers(i)%name ),                              &
                       MPI_CHARACTER, 0, MPI_COMM_WORLD, istat )
       CALL MPI_BCAST( m_couplers(i)%id,           1, MPI_INTEGER, 0,                              &
                       MPI_COMM_WORLD, istat )
       CALL MPI_BCAST( m_couplers(i)%Parent_id,    1, MPI_INTEGER, 0,                              &
                       MPI_COMM_WORLD, istat )
       CALL MPI_BCAST( m_couplers(i)%npe_total,    1, MPI_INTEGER, 0,                              &
                       MPI_COMM_WORLD, istat )
       CALL MPI_BCAST( m_couplers(i)%lower_left_x, 1, MPI_REAL,    0,                              &
                       MPI_COMM_WORLD, istat )
       CALL MPI_BCAST( m_couplers(i)%lower_left_y, 1, MPI_REAL,    0,                              &
                       MPI_COMM_WORLD, istat )
    ENDDO
    CALL MPI_BCAST( nesting_mode, LEN( nesting_mode ), MPI_CHARACTER, 0, MPI_COMM_WORLD, istat )
    CALL MPI_BCAST( nesting_datatransfer_mode, LEN(nesting_datatransfer_mode), MPI_CHARACTER, 0,   &
                    MPI_COMM_WORLD, istat )
    CALL MPI_BCAST( anterpolation_buffer_width, 1, MPI_INT, 0, MPI_COMM_WORLD, istat )
!
!-- Assign global MPI processes to individual models by setting the couple id
    DO  i = 1, m_ncpl
       IF ( m_world_rank >= start_pe(i)  .AND.  m_world_rank < start_pe(i+1) )  THEN
          m_my_cpl_id = i
          EXIT
       ENDIF
    ENDDO
    m_my_cpl_rank = m_world_rank - start_pe(i)
!
!-- MPI_COMM_WORLD is the communicator for ALL models (MPI-1 approach). The communictors for the
!-- individual models as created by MPI_COMM_SPLIT. The color of the model is represented by the
!-- coupler id
    CALL MPI_COMM_SPLIT( MPI_COMM_WORLD, m_my_cpl_id, m_my_cpl_rank, comm, istat )
!
!-- Get size and rank of the model running on this process
    CALL  MPI_COMM_RANK( comm, m_model_rank, istat )
    CALL  MPI_COMM_SIZE( comm, m_model_npes, istat )
!
!-- Broadcast (from process 0) the parent id and id of every model
    DO  i = 1, m_ncpl
       CALL MPI_BCAST( m_couplers(i)%parent_id, 1, MPI_INTEGER, 0, MPI_COMM_WORLD, istat )
       CALL MPI_BCAST( m_couplers(i)%id,        1, MPI_INTEGER, 0, MPI_COMM_WORLD, istat )
    ENDDO
!
!-- Save the current model communicator for pmc internal use
    m_model_comm = comm

!
!-- Create intercommunicator between the parent and children.
!-- MPI_INTERCOMM_CREATE creates an intercommunicator between 2 groups of different colors. The
!-- grouping was done above with MPI_COMM_SPLIT. A duplicate of MPI_COMM_WORLD is created and used
!-- as peer communicator (peer_comm) for MPI_INTERCOMM_CREATE.
    CALL MPI_COMM_DUP( MPI_COMM_WORLD, peer_comm, ierr )
    DO  i = 2, m_ncpl
       IF ( m_couplers(i)%parent_id == m_my_cpl_id )  THEN
!
!--       Identify all children models of the current model and create inter-communicators to
!--       connect between the current model and its children models.
          tag = 500 + i
          CALL MPI_INTERCOMM_CREATE( comm, 0, peer_comm, start_pe(i), tag, m_to_child_comm(i),     &
                                     istat )
          childcount = childcount + 1
          activeparent(i) = 1
       ELSEIF ( i == m_my_cpl_id)  THEN
!
!--       Create an inter-communicator to connect between the current model and its parent model.
          tag = 500 + i
          CALL MPI_INTERCOMM_CREATE( comm, 0, peer_comm, start_pe(m_couplers(i)%parent_id), tag,   &
                                     m_to_parent_comm, istat )
       ENDIF
    ENDDO
!
!-- If I am a parent, count the number of children I have. Although this loop is symmetric on all
!-- processes, the "activeparent" flag is true (==1) on the respective individual process only.
    ALLOCATE( pmc_parent_for_child(childcount+1) )

    childcount = 0
    DO  i = 2, m_ncpl
       IF ( activeparent(i) == 1 )  THEN
          childcount = childcount + 1
          pmc_parent_for_child(childcount) = i
       ENDIF
    ENDDO
!
!-- Get the size of the parent model
    IF ( m_my_cpl_id > 1 )  THEN
       CALL MPI_COMM_REMOTE_SIZE( m_to_parent_comm, m_parent_remote_size, istat )
    ELSE
!
!--    The root model does not have a parent
       m_parent_remote_size = -1
    ENDIF
!
!-- Set myid to non-zero value except for the root domain. This is a setting for the message routine
!-- which is called at the end of pmci_init. That routine outputs messages for myid = 0, only.
!-- However, myid has not been assigened so far, so that all processes of the root model would
!-- output a message. To avoid this, set myid to some other value except for process 0 of the root
!-- domain.
    IF ( m_world_rank /= 0 )  myid = 1

 END SUBROUTINE PMC_init_model


!--------------------------------------------------------------------------------------------------!
! Description:
! ------------
!> @Todo: Missing subroutine description.
!--------------------------------------------------------------------------------------------------!
 SUBROUTINE pmc_get_model_info( comm_world_nesting, cpl_id, cpl_name, cpl_parent_id, lower_left_x, &
                                lower_left_y, ncpl, npe_total, request_for_cpl_id )
!
!-- Provide module private variables of the pmc for PALM

    USE kinds

    IMPLICIT NONE

    CHARACTER(LEN=*), INTENT(OUT), OPTIONAL ::  cpl_name   !<

    INTEGER, INTENT(IN), OPTIONAL ::  request_for_cpl_id   !<

    INTEGER, INTENT(OUT), OPTIONAL ::  comm_world_nesting  !<
    INTEGER, INTENT(OUT), OPTIONAL ::  cpl_id              !<
    INTEGER, INTENT(OUT), OPTIONAL ::  cpl_parent_id       !<
    INTEGER, INTENT(OUT), OPTIONAL ::  ncpl                !<
    INTEGER, INTENT(OUT), OPTIONAL ::  npe_total           !<

    INTEGER ::  requested_cpl_id                           !<

    REAL(wp), INTENT(OUT), OPTIONAL ::  lower_left_x       !<
    REAL(wp), INTENT(OUT), OPTIONAL ::  lower_left_y       !<

!
!-- Set the requested coupler id
    IF ( PRESENT( request_for_cpl_id ) )  THEN
       requested_cpl_id = request_for_cpl_id
!
!--    Check for allowed range of values
       IF ( requested_cpl_id < 1  .OR.  requested_cpl_id > m_ncpl )  RETURN
    ELSE
       requested_cpl_id = m_my_cpl_id
    ENDIF
!
!-- Return the requested information
    IF ( PRESENT( comm_world_nesting )  )  THEN
       comm_world_nesting = m_world_comm
    ENDIF
    IF ( PRESENT( cpl_id )        )  THEN
       cpl_id = requested_cpl_id
    ENDIF
    IF ( PRESENT( cpl_parent_id ) )  THEN
       cpl_parent_id = m_couplers(requested_cpl_id)%parent_id
    ENDIF
    IF ( PRESENT( cpl_name )      )  THEN
       cpl_name = m_couplers(requested_cpl_id)%name
    ENDIF
    IF ( PRESENT( ncpl )          )  THEN
       ncpl = m_ncpl
    ENDIF
    IF ( PRESENT( npe_total )     )  THEN
       npe_total = m_couplers(requested_cpl_id)%npe_total
    ENDIF
    IF ( PRESENT( lower_left_x )  )  THEN
       lower_left_x = m_couplers(requested_cpl_id)%lower_left_x
    ENDIF
    IF ( PRESENT( lower_left_y )  )  THEN
       lower_left_y = m_couplers(requested_cpl_id)%lower_left_y
    ENDIF

 END SUBROUTINE pmc_get_model_info



 LOGICAL function pmc_is_rootmodel( )

    IMPLICIT NONE

    pmc_is_rootmodel = ( m_my_cpl_id == 1 )

 END FUNCTION pmc_is_rootmodel



!--------------------------------------------------------------------------------------------------!
! Description:
! ------------
!> @Todo: Missing subroutine description.
!--------------------------------------------------------------------------------------------------!
 SUBROUTINE read_coupling_layout( nesting_datatransfer_mode, nesting_mode,                         &
                                  anterpolation_buffer_width, pmc_status )

    IMPLICIT NONE

    CHARACTER(LEN=7), INTENT(INOUT) ::  nesting_datatransfer_mode  !<
    CHARACTER(LEN=8), INTENT(INOUT) ::  nesting_mode               !<

    INTEGER, INTENT(INOUT)      ::  anterpolation_buffer_width  !< Boundary buffer width for anterpolation
    INTEGER(iwp), INTENT(INOUT) ::  pmc_status                  !<

    INTEGER(iwp) ::  bad_llcorner  !<
    INTEGER(iwp) ::  i             !<
    INTEGER(iwp) ::  istat         !<

    TYPE(pmc_layout), DIMENSION(pmc_max_models) ::  domain_layouts  !<

    NAMELIST /nesting_parameters/  domain_layouts,                                                 &
                                   nesting_datatransfer_mode,                                      &
                                   nesting_mode,                                                   &
                                   anterpolation_buffer_width

!
!-- Initialize some coupling variables
    domain_layouts(1:pmc_max_models)%id = -1
    m_ncpl =   0

    pmc_status = pmc_status_ok
!
!-- Open the NAMELIST-file and read the nesting layout
    CALL check_open( 11 )
    READ ( 11, nesting_parameters, IOSTAT = istat )
!
!-- Set filepointer to the beginning of the file. Otherwise process 0 will later be unable to read
!-- the inipar-NAMELIST
    REWIND ( 11 )

    IF ( istat < 0 )  THEN
!
!--    No nesting_parameters-NAMELIST found
       pmc_status = pmc_no_namelist_found
       RETURN
    ELSEIF ( istat > 0 )  THEN
!
!--    Errors in reading nesting_parameters-NAMELIST
       pmc_status = pmc_namelist_error
       RETURN
    ENDIF
!
!-- Output location message
    CALL location_message( 'initialize communicators for nesting', 'start' )
!
!-- Assign the layout to the corresponding internally used variable m_couplers
    m_couplers = domain_layouts
!
!-- Get the number of nested models given in the nesting_parameters-NAMELIST
    DO  i = 1, pmc_max_models
!
!--    When id=-1 is found for the first time, the list of domains is finished
       IF ( m_couplers(i)%id == -1  .OR.  i == pmc_max_models )  THEN
          IF ( m_couplers(i)%id == -1 )  THEN
             m_ncpl = i - 1
             EXIT
          ELSE
             m_ncpl = pmc_max_models
          ENDIF
       ENDIF
    ENDDO
!
!-- Make sure that all domains have equal lower left corner in case of vertical nesting
    IF ( nesting_mode == 'vertical' )  THEN
       bad_llcorner = 0
       DO  i = 1, m_ncpl
          IF ( domain_layouts(i)%lower_left_x /= 0.0_wp .OR.                                       &
               domain_layouts(i)%lower_left_y /= 0.0_wp )  THEN
             bad_llcorner = bad_llcorner + 1
             domain_layouts(i)%lower_left_x = 0.0_wp
             domain_layouts(i)%lower_left_y = 0.0_wp
          ENDIF
       ENDDO
       IF ( bad_llcorner /= 0)  THEN
          WRITE( message_string, *)  'at least one dimension of lower ',                           &
                                     'left corner of one domain is not 0. ',                       &
                                     'All lower left corners were set to (0, 0)'
          CALL message( 'read_coupling_layout', 'PA0427', 0, 0, 0, 6, 0 )
       ENDIF
    ENDIF

    CALL location_message( 'initialize communicators for nesting', 'finished' )

 END SUBROUTINE read_coupling_layout

#endif
 END MODULE pmc_handle_communicator