Removal of mpp_open

Commit #1
---------

Removes calls to mpp_open, and replaces then with FATAL MOM_error calls
when present.

This also introduces the idea where only domain-decomposed files are
used with infra IO.  I've floated this idea a few times and people seem
supportive, but it may not necessarily be embraced by everyone.

Also moves Vertical_coordinate.nc from infra to native netCDF.

This is primarily a trial balloon to see how the regression suite holds
up.

Commit #2
---------

mpp_open removal

This formally removes the mpp_open functions, along with the FMS_writes
control flag.  Hopefully there is nothing much interesting here.

Also removed open_file_unit since it's no longer used, and renamed
open_file_type to open_file since the interface serves no purpose.

config_src/drivers/nuopc_cap/mom_cap.F90

@@ -11,7 +11,6 @@ module MOM_cap_mod
 use mpp_domains_mod,          only: domain2d, mpp_get_compute_domain, mpp_get_compute_domains
 use mpp_domains_mod,          only: mpp_get_ntile_count, mpp_get_pelist, mpp_get_global_domain
 use mpp_domains_mod,          only: mpp_get_domain_npes
-use mpp_io_mod,               only: mpp_open, MPP_RDONLY, MPP_ASCII, MPP_OVERWR, MPP_APPEND, mpp_close, MPP_SINGLE
 use mpp_mod,                  only: stdlog, stdout, mpp_root_pe, mpp_clock_id
 use mpp_mod,                  only: mpp_clock_begin, mpp_clock_end, MPP_CLOCK_SYNC
 use mpp_mod,                  only: MPP_CLOCK_DETAILED, CLOCK_COMPONENT, MAXPES

config_src/infra/FMS2/MOM_io_infra.F90

@@ -23,7 +23,7 @@ module MOM_io_infra
 use fms_io_mod,           only : file_exist, field_exist, field_size, read_data
 use fms_io_mod,           only : fms_io_exit, get_filename_appendix
 use mpp_domains_mod,      only : mpp_get_compute_domain, mpp_get_global_domain
-use mpp_io_mod,           only : mpp_open, mpp_close, mpp_flush
+use mpp_io_mod,           only : mpp_close, mpp_flush
 use mpp_io_mod,           only : mpp_write_meta, mpp_write
 use mpp_io_mod,           only : mpp_get_atts, mpp_attribute_exist
 use mpp_io_mod,           only : mpp_get_axes, mpp_axistype=>axistype, mpp_get_axis_data
@@ -63,11 +63,6 @@ module MOM_io_infra
   module procedure MOM_file_exists
 end interface
 
-!> Open a file (or fileset) for parallel or single-file I/O.
-interface open_file
-  module procedure open_file_type, open_file_unit
-end interface open_file
-
 !> Read a data field from a file
 interface read_field
   module procedure read_field_4d
@@ -142,8 +137,8 @@ module MOM_io_infra
 end type axistype
 
 !> For now, these module-variables are hard-coded to exercise the new FMS2 interfaces.
+! TODO: Delete these
 logical :: FMS2_reads  = .true.
-logical :: FMS2_writes = .true.
 
 contains
 
@@ -212,13 +207,6 @@ subroutine close_file_unit(iounit)
 
   logical :: unit_is_open
 
-  ! NOTE: Files opened by `mpp_open` must be closed by `mpp_close`.  Otherwise,
-  ! an error will occur during `fms_io_exit`.
-  !
-  ! Since there is no way to check if `fms_io_init` was called, we are forced
-  ! to visually confirm that the input unit was not created by `mpp_open`.
-  !
-  ! After `mpp_open` has been removed, this message can be deleted.
   inquire(iounit, opened=unit_is_open)
   if (unit_is_open) close(iounit)
 end subroutine close_file_unit
@@ -299,35 +287,7 @@ subroutine write_version(version, tag, unit)
 end subroutine write_version
 
 !> open_file opens a file for parallel or single-file I/O.
-subroutine open_file_unit(unit, filename, action, form, threading, fileset, nohdrs, domain, MOM_domain)
-  integer,                  intent(out) :: unit   !< The I/O unit for the opened file
-  character(len=*),         intent(in)  :: filename !< The name of the file being opened
-  integer,        optional, intent(in)  :: action !< A flag indicating whether the file can be read
-                                                  !! or written to and how to handle existing files.
-  integer,        optional, intent(in)  :: form   !< A flag indicating the format of a new file.  The
-                                                  !! default is ASCII_FILE, but NETCDF_FILE is also common.
-  integer,        optional, intent(in)  :: threading !< A flag indicating whether one (SINGLE_FILE)
-                                                  !! or multiple PEs (MULTIPLE) participate in I/O.
-                                                  !! With the default, the root PE does I/O.
-  integer,        optional, intent(in)  :: fileset !< A flag indicating whether multiple PEs doing I/O due
-                                                  !! to threading=MULTIPLE write to the same file (SINGLE_FILE)
-                                                  !! or to one file per PE (MULTIPLE, the default).
-  logical,        optional, intent(in)  :: nohdrs !< If nohdrs is .TRUE., headers are not written to
-                                                  !! ASCII files.  The default is .false.
-  type(domain2d), optional, intent(in)  :: domain !< A domain2d type that describes the decomposition
-  type(MOM_domain_type), optional, intent(in) :: MOM_Domain !< A MOM_Domain that describes the decomposition
-
-  if (present(MOM_Domain)) then
-    call mpp_open(unit, filename, action=action, form=form, threading=threading, fileset=fileset, &
-                  nohdrs=nohdrs, domain=MOM_Domain%mpp_domain)
-  else
-    call mpp_open(unit, filename, action=action, form=form, threading=threading, fileset=fileset, &
-                  nohdrs=nohdrs, domain=domain)
-  endif
-end subroutine open_file_unit
-
-!> open_file opens a file for parallel or single-file I/O.
-subroutine open_file_type(IO_handle, filename, action, MOM_domain, threading, fileset)
+subroutine open_file(IO_handle, filename, action, MOM_domain, threading, fileset)
   type(file_type),          intent(inout) :: IO_handle !< The handle for the opened file
   character(len=*),         intent(in)    :: filename !< The path name of the file being opened
   integer,        optional, intent(in)    :: action !< A flag indicating whether the file can be read
@@ -355,63 +315,60 @@ subroutine open_file_type(IO_handle, filename, action, MOM_domain, threading, fi
   integer :: index_nc
 
   if (IO_handle%open_to_write) then
-    call MOM_error(WARNING, "open_file_type called for file "//trim(filename)//&
+    call MOM_error(WARNING, "open_file called for file "//trim(filename)//&
         " with an IO_handle that is already open to to write.")
     return
   endif
   if (IO_handle%open_to_read) then
-    call MOM_error(FATAL, "open_file_type called for file "//trim(filename)//&
+    call MOM_error(FATAL, "open_file called for file "//trim(filename)//&
         " with an IO_handle that is already open to to read.")
   endif
 
   file_mode = WRITEONLY_FILE ; if (present(action)) file_mode = action
 
-  if (FMS2_writes .and. present(MOM_Domain)) then
-    if (.not.associated(IO_handle%fileobj)) allocate (IO_handle%fileobj)
+  ! Domains are currently required to use FMS I/O.
+  ! NOTE: This is required due to issues with string-based attributes in
+  ! certain compilers, but could be relaxes if those issues are resolved.
+  if (.not. present(MOM_Domain)) &
+    call MOM_error(FATAL, 'open_file: FMS I/O requires a domain input.')
 
-    ! The FMS1 interface automatically appends .nc if necessary, but FMS2 interface does not.
-    index_nc = index(trim(filename), ".nc")
-    if (index_nc > 0) then
-      filename_tmp = trim(filename)
-    else
-      filename_tmp = trim(filename)//".nc"
-      if (is_root_PE()) call MOM_error(WARNING, "Open_file is appending .nc to the filename "//trim(filename))
-    endif
+  if (.not.associated(IO_handle%fileobj)) allocate (IO_handle%fileobj)
 
-    if (file_mode == WRITEONLY_FILE) then ; mode = "write"
-    elseif (file_mode == APPEND_FILE) then ; mode = "append"
-    elseif (file_mode == OVERWRITE_FILE) then ; mode = "overwrite"
-    elseif (file_mode == READONLY_FILE) then ; mode = "read"
-    else
-      call MOM_error(FATAL, "open_file_type called with unrecognized action.")
-    endif
-
-    IO_handle%num_times = 0
-    IO_handle%file_time = 0.0
-    if ((file_mode == APPEND_FILE) .and. file_exists(filename_tmp, MOM_Domain)) then
-      ! Determine the latest file time and number of records so far.
-      success = fms2_open_file(fileObj_read, trim(filename_tmp), "read", MOM_domain%mpp_domain)
-      call get_unlimited_dimension_name(fileObj_read, dim_unlim_name)
-      if (len_trim(dim_unlim_name) > 0) &
-        call get_dimension_size(fileObj_read, trim(dim_unlim_name), IO_handle%num_times)
-      if (IO_handle%num_times > 0) &
-        call fms2_read_data(fileObj_read, trim(dim_unlim_name), IO_handle%file_time, &
-                            unlim_dim_level=IO_handle%num_times)
-      call fms2_close_file(fileObj_read)
-    endif
+  ! The FMS1 interface automatically appends .nc if necessary, but FMS2 interface does not.
+  index_nc = index(trim(filename), ".nc")
+  if (index_nc > 0) then
+    filename_tmp = trim(filename)
+  else
+    filename_tmp = trim(filename)//".nc"
+    if (is_root_PE()) call MOM_error(WARNING, "Open_file is appending .nc to the filename "//trim(filename))
+  endif
 
-    success = fms2_open_file(IO_handle%fileobj, trim(filename_tmp), trim(mode), MOM_domain%mpp_domain)
-    if (.not.success) call MOM_error(FATAL, "Unable to open file "//trim(filename_tmp))
-    IO_handle%FMS2_file = .true.
-  elseif (present(MOM_Domain)) then
-    call mpp_open(IO_handle%unit, filename, action=file_mode, form=NETCDF_FILE, threading=threading, &
-                  fileset=fileset, domain=MOM_Domain%mpp_domain)
-    IO_handle%FMS2_file = .false.
+  if (file_mode == WRITEONLY_FILE) then ; mode = "write"
+  elseif (file_mode == APPEND_FILE) then ; mode = "append"
+  elseif (file_mode == OVERWRITE_FILE) then ; mode = "overwrite"
+  elseif (file_mode == READONLY_FILE) then ; mode = "read"
   else
-    call mpp_open(IO_handle%unit, filename, action=file_mode, form=NETCDF_FILE, threading=threading, &
-                  fileset=fileset)
-    IO_handle%FMS2_file = .false.
+    call MOM_error(FATAL, "open_file called with unrecognized action.")
   endif
+
+  IO_handle%num_times = 0
+  IO_handle%file_time = 0.0
+  if ((file_mode == APPEND_FILE) .and. file_exists(filename_tmp, MOM_Domain)) then
+    ! Determine the latest file time and number of records so far.
+    success = fms2_open_file(fileObj_read, trim(filename_tmp), "read", MOM_domain%mpp_domain)
+    call get_unlimited_dimension_name(fileObj_read, dim_unlim_name)
+    if (len_trim(dim_unlim_name) > 0) &
+      call get_dimension_size(fileObj_read, trim(dim_unlim_name), IO_handle%num_times)
+    if (IO_handle%num_times > 0) &
+      call fms2_read_data(fileObj_read, trim(dim_unlim_name), IO_handle%file_time, &
+                          unlim_dim_level=IO_handle%num_times)
+    call fms2_close_file(fileObj_read)
+  endif
+
+  success = fms2_open_file(IO_handle%fileobj, trim(filename_tmp), trim(mode), MOM_domain%mpp_domain)
+  if (.not.success) call MOM_error(FATAL, "Unable to open file "//trim(filename_tmp))
+  ! TODO: Drop this
+  IO_handle%FMS2_file = .true.
   IO_handle%filename = trim(filename)
 
   if (file_mode == READONLY_FILE) then
@@ -420,7 +377,7 @@ subroutine open_file_type(IO_handle, filename, action, MOM_domain, threading, fi
     IO_handle%open_to_read = .false. ; IO_handle%open_to_write = .true.
   endif
 
-end subroutine open_file_type
+end subroutine open_file
 
 !> open_file opens an ascii file for parallel or single-file I/O using Fortran read and write calls.
 subroutine open_ASCII_file(unit, file, action, threading, fileset)
@@ -830,10 +787,7 @@ subroutine get_axis_data( axis, dat )
     if (size(axis%ax_data) > size(dat)) call MOM_error(FATAL, &
       "get_axis_data called with too small of an output data array for "//trim(axis%name))
     do i=1,size(axis%ax_data) ; dat(i) = axis%ax_data(i) ; enddo
-  elseif (.not.FMS2_writes) then
-    call mpp_get_axis_data( axis%AT, dat )
   endif
-
 end subroutine get_axis_data
 
 !> This routine uses the fms_io subroutine read_data to read a scalar named

src/ALE/MOM_regridding.F90

@@ -7,7 +7,7 @@ module MOM_regridding
 use MOM_file_parser,   only : param_file_type, get_param, log_param
 use MOM_io,            only : file_exists, field_exists, field_size, MOM_read_data
 use MOM_io,            only : vardesc, var_desc, SINGLE_FILE
-use MOM_io,            only : MOM_infra_file, MOM_field
+use MOM_io,            only : MOM_netCDF_file, MOM_field
 use MOM_io,            only : create_MOM_file, MOM_write_field
 use MOM_io,            only : verify_variable_units, slasher
 use MOM_unit_scaling,  only : unit_scale_type
@@ -2214,7 +2214,7 @@ subroutine write_regrid_file( CS, GV, filepath )
 
   type(vardesc)      :: vars(2)
   type(MOM_field)    :: fields(2)
-  type(MOM_infra_file) :: IO_handle ! The I/O handle of the fileset
+  type(MOM_netCDF_file) :: IO_handle ! The I/O handle of the fileset
   real               :: ds(GV%ke), dsi(GV%ke+1)
 
   if (CS%regridding_scheme == REGRIDDING_HYBGEN) then

src/framework/MOM_io.F90

@@ -333,12 +333,15 @@ subroutine create_MOM_file(IO_handle, filename, vars, novars, fields, &
     IsgB = dG%IsgB ; IegB = dG%IegB ; JsgB = dG%JsgB ; JegB = dG%JegB
   endif
 
-  if (domain_set .and. (num_PEs() == 1)) thread = SINGLE_FILE
+  ! Previously, thread was set to SINGLE_FILE for single-PE jobs; we now
+  ! base this solely on the presence of a domain.
+  if (domain_set) thread = MULTIPLE
 
   one_file = .true.
   if (domain_set) one_file = (thread == SINGLE_FILE)
 
   if (one_file) then
+    ! thread must equal SINGLE_FILE, so why pass the variable?
     call IO_handle%open(filename, action=OVERWRITE_FILE, threading=thread)
   else
     call IO_handle%open(filename, action=OVERWRITE_FILE, MOM_domain=Domain)