From 3a198f5fe542ba9b23f416427fa19e0c8bae0a93 Mon Sep 17 00:00:00 2001
From: Justin Bich <ju_bi1@uni-bremen.de>
Date: Tue, 16 Jan 2024 13:12:34 +0100
Subject: [PATCH] Change mpifx_comm to mpi_f08

---
 lib/mpifx_comm.fpp | 79 ++++++++++++++++++++++++++++++++--------------
 1 file changed, 56 insertions(+), 23 deletions(-)

diff --git a/lib/mpifx_comm.fpp b/lib/mpifx_comm.fpp
index ac30042..57ab8d9 100644
--- a/lib/mpifx_comm.fpp
+++ b/lib/mpifx_comm.fpp
@@ -1,6 +1,6 @@
 !> Contains the extended MPI communicator.
 module mpifx_comm_module
-  use mpi
+  use mpi_f08
   use mpifx_helper_module, only : getoptarg, handle_errorflag
   implicit none
   private
@@ -9,14 +9,19 @@ module mpifx_comm_module
 
   !> MPI communicator with some additional information.
   type mpifx_comm
-    integer :: id         !< Communicator id.
-    integer :: size       !< Nr. of processes (size).
-    integer :: rank       !< Rank of the current process.
-    integer :: leadrank   !< Index of the lead node.
-    logical :: lead       !< True if current process is the lead (rank == 0).
+    integer :: id           !< Communicator id.
+    type(mpi_comm) :: comm  !< MPI communicator handle.
+    integer :: size         !< Nr. of processes (size).
+    integer :: rank         !< Rank of the current process.
+    integer :: leadrank     !< Index of the lead node.
+    logical :: lead         !< True if current process is the lead (rank == 0).
   contains
+
     !> Initializes the MPI environment.
-    procedure :: init => mpifx_comm_init
+    procedure, private :: mpifx_comm_from_id
+    procedure, private :: mpifx_comm_from_type
+
+    generic :: init => mpifx_comm_from_id, mpifx_comm_from_type
 
     !> Creates a new communicator by splitting the old one.
     procedure :: split => mpifx_comm_split
@@ -31,27 +36,32 @@ module mpifx_comm_module
 
 contains
 
-  !> Initializes a communicator to contain all processes.
+  !> Initializes a communicator from mpi_comm type
   !!
   !! \param self  Initialized instance on exit.
-  !! \param commid  MPI Communicator ID (default: \c MPI_COMM_WORLD)
-  !! \param error  Error flag on return containing the first error occuring
+  !! \param comm MPI Communicator (default: \c MPI_COMM_WORLD)
+  !! \param error  Error flag on return containing the first error occurring
   !!     during the calls mpi_comm_size and mpi_comm_rank.
   !!
-  subroutine mpifx_comm_init(self, commid, error)
+  subroutine mpifx_comm_from_type(self, comm, error)
     class(mpifx_comm), intent(out) :: self
-    integer, intent(in), optional :: commid
+    type(mpi_comm), intent(in), optional :: comm
     integer, intent(out), optional :: error
 
     integer :: error0
 
-    call getoptarg(MPI_COMM_WORLD, self%id, commid)
-    call mpi_comm_size(self%id, self%size, error0)
+    if (present(comm)) then
+      self%comm = comm
+    else
+      self%comm = MPI_COMM_WORLD
+    end if
+    self%id = self%comm%mpi_val
+    call mpi_comm_size(self%comm, self%size, error0)
     call handle_errorflag(error0, "mpi_comm_size() in mpifx_comm_init()", error)
     if (error0 /= 0) then
       return
     end if
-    call mpi_comm_rank(self%id, self%rank, error0)
+    call mpi_comm_rank(self%comm, self%rank, error0)
     call handle_errorflag(error0, "mpi_comm_rank() in mpifx_comm_init()", error)
     if (error0 /= 0) then
       return
@@ -59,7 +69,27 @@ contains
     self%leadrank = 0
     self%lead = (self%rank == self%leadrank)
 
-  end subroutine mpifx_comm_init
+  end subroutine mpifx_comm_from_type
+
+
+  !> Initializes a communicator from a numerical id.
+  !!
+  !! \param self  Initialized instance on exit.
+  !! \param commid  Numerical MPI Communicator ID
+  !! \param error  Error flag on return containing the first error occurring
+  !!     during the calls mpi_comm_size and mpi_comm_rank.
+  !!
+  subroutine mpifx_comm_from_id(self, commid, error)
+    class(mpifx_comm), intent(out) :: self
+    integer, intent(in) :: commid
+    integer, intent(out), optional :: error
+
+    type(mpi_comm) :: newcomm
+
+    newcomm%mpi_val = commid
+    call self%mpifx_comm_from_type(newcomm, error)
+
+  end subroutine mpifx_comm_from_id
 
 
   !> Creates a new communicators by splitting the old one.
@@ -102,14 +132,15 @@ contains
     class(mpifx_comm), intent(out) :: newcomm
     integer, intent(out), optional :: error
 
-    integer :: error0, newcommid
+    integer :: error0
+    type(mpi_comm) :: newmpicomm
 
-    call mpi_comm_split(self%id, splitkey, rankkey, newcommid, error0)
+    call mpi_comm_split(self%comm, splitkey, rankkey, newmpicomm, error0)
     call handle_errorflag(error0, "mpi_comm_split() in mpifx_comm_split()", error)
     if (error0 /= 0) then
       return
     end if
-    call newcomm%init(newcommid, error)
+    call newcomm%init(newmpicomm, error)
 
   end subroutine mpifx_comm_split
 
@@ -150,14 +181,15 @@ contains
     class(mpifx_comm), intent(out) :: newcomm
     integer, intent(out), optional :: error
 
-    integer :: error0, newcommid
+    integer :: error0
+    type(mpi_comm) :: newmpicomm
 
-    call mpi_comm_split_type(self%id, splittype, rankkey, MPI_INFO_NULL, newcommid, error0)
+    call mpi_comm_split_type(self%comm, splittype, rankkey, MPI_INFO_NULL, newmpicomm, error0)
     call handle_errorflag(error0, "mpi_comm_split_type() in mpifx_comm_split_type()", error)
     if (error0 /= 0) then
       return
     end if
-    call newcomm%init(newcommid, error)
+    call newcomm%init(newmpicomm, error)
 
   end subroutine mpifx_comm_split_type
 
@@ -173,7 +205,8 @@ contains
 
     integer :: error
 
-    call mpi_comm_free(self%id, error)
+    call mpi_comm_free(self%comm, error)
+    self%id = self%comm%mpi_val
 
   end subroutine mpifx_comm_free