cp_output_handling.F

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!--------------------------------------------------------------------------------------------------!
!   CP2K: A general program to perform molecular dynamics simulations                              !
!   Copyright 2000-2026 CP2K developers group <https://cp2k.org>                                   !
!                                                                                                  !
!   SPDX-License-Identifier: GPL-2.0-or-later                                                      !
!--------------------------------------------------------------------------------------------------!
 
! **************************************************************************************************
!> \brief routines to handle the output, The idea is to remove the
!>      decision of wheter to output and what to output from the code
!>      that does the output, and centralize it here.
!> \note
!>      These were originally together with the log handling routines,
!>      but have been spawned off. Some dependencies are still there,
!>      and some of the comments about log handling also applies to output
!>      handling: @see cp_log_handling
!> \par History
!>      12.2001 created [fawzi]
!>      08.2002 updated to new logger [fawzi]
!>      10.2004 big rewrite of the output methods, connected to the new
!>              input, and iteration_info [fawzi]
!>      08.2005 property flags [fawzi]
!> \author Fawzi Mohamed
! **************************************************************************************************
MODULE cp_output_handling
   USE cp_files,                        ONLY: close_file,&
                                              open_file
   USE cp_iter_types,                   ONLY: cp_iteration_info_release,&
                                              cp_iteration_info_retain,&
                                              cp_iteration_info_type,&
                                              each_desc_labels,&
                                              each_possible_labels,&
                                              iter_notice,&
                                              iter_silent
   USE cp_log_handling,                 ONLY: cp_logger_generate_filename,&
                                              cp_logger_get_default_unit_nr,&
                                              cp_logger_get_unit_nr,&
                                              cp_logger_type,&
                                              cp_to_string
   USE input_keyword_types,             ONLY: keyword_create,&
                                              keyword_release,&
                                              keyword_type
   USE input_section_types,             ONLY: section_add_keyword,&
                                              section_add_subsection,&
                                              section_create,&
                                              section_release,&
                                              section_type,&
                                              section_vals_get_subs_vals,&
                                              section_vals_type,&
                                              section_vals_val_get
   USE kinds,                           ONLY: default_path_length,&
                                              default_string_length
   USE machine,                         ONLY: m_mov
   USE memory_utilities,                ONLY: reallocate
   USE message_passing,                 ONLY: mp_file_delete,&
                                              mp_file_get_amode,&
                                              mp_file_type
   USE string_utilities,                ONLY: compress,&
                                              newline,&
                                              s2a
#include "../base/base_uses.f90"
 
   IMPLICIT NONE
   PRIVATE
 
   LOGICAL, PRIVATE, PARAMETER :: debug_this_module = .true.
   CHARACTER(len=*), PARAMETER, PRIVATE :: moduleN = 'cp_output_handling'
   PUBLIC :: cp_print_key_should_output, cp_iterate, cp_get_iter_level_by_name, cp_get_iter_nr
   PUBLIC :: cp_add_iter_level, cp_rm_iter_level
   PUBLIC :: cp_iter_string, cp_print_key_section_create
   PUBLIC :: cp_print_key_unit_nr, cp_print_key_finished_output
   PUBLIC :: cp_print_key_generate_filename, cp_printkey_is_on
 
   INTEGER, PARAMETER, PUBLIC               :: add_last_no = 0, &
                                               add_last_numeric = 1, &
                                               add_last_symbolic = 2
   INTEGER, PARAMETER, PUBLIC               :: silent_print_level = 0, &
                                               low_print_level = 1, &
                                               medium_print_level = 2, &
                                               high_print_level = 3, &
                                               debug_print_level = 4
 
!! flags controlling the printing and storing of a property.
!!
!! cp_out_none: do not calculate the property
!! cp_out_file_if  : if the printkey says it calculate and output the property
!! cp_out_store_if : if the printkey says it calculate and store in memory
!!                   the property
!! cp_out_file_each: calculate and output the property with the same periodicity
!!                   as said in the printkey (irrespective of the activation of
!!                   the printkey)
!! cp_out_store_each: calculate and store the property with the same periodicity
!!                   as said in the printkey (irrespective of the activation of
!!                   the printkey)
!! cp_out_file: always calculate and output the property
!! cp_out_store: always calculate and store in memory the property
!! cp_out_calc: just calculate the value (independently from the fact that there
!!              should be output)
!! cp_out_default: the default value for property flags (cp_out_file_if)
!!
!! this flags can be ior-ed together:
!! ior(cp_out_file_if,cp_out_store_if): if the printkey says it both print
!!                                          and store the property
!!
!! there is no guarantee that a property is not stored if it is not necessary
!! not all printkeys have a control flag
   INTEGER, PUBLIC, PARAMETER :: cp_p_file_if = 3, cp_p_store_if = 4, &
                                 cp_p_store = 2, cp_p_file = 1, cp_p_file_each = 5, cp_p_store_each = 6, cp_p_calc = 7
   INTEGER, PUBLIC, PARAMETER :: cp_out_none = 0, cp_out_file_if = ibset(0, cp_p_file_if), &
                                 cp_out_store_if = ibset(0, cp_p_store_if), cp_out_file = ibset(0, cp_p_file), &
                                 cp_out_store = ibset(0, cp_p_store), cp_out_calc = ibset(0, cp_p_calc), &
                                 cp_out_file_each = ibset(0, cp_p_file_each), &
                                 cp_out_store_each = ibset(0, cp_p_store_each), &
                                 cp_out_default = cp_out_file_if
 
! Flag determining if MPI I/O should be enabled for functions that support it
   LOGICAL, PRIVATE, SAVE      :: enable_mpi_io = .false.
! Public functions to set/get the flags
   PUBLIC :: cp_mpi_io_set, cp_mpi_io_get
 
CONTAINS
 
! **************************************************************************************************
!> \brief creates a print_key section
!> \param print_key_section the print key to create
!> \param location from where in the source code cp_print_key_section_create() is called
!> \param name the name of the print key
!> \param description the description of the print key
!> \param print_level print level starting at which the printing takes place
!>        (defaults to debug_print_level)
!> \param each_iter_names ...
!> \param each_iter_values ...
!> \param add_last ...
!> \param filename ...
!> \param common_iter_levels ...
!> \param citations ...
!> \param unit_str specifies an unit of measure for output quantity. If not
!>        provided the control is totally left to how the output was coded
!>        (i.e. USERS have no possibility to change it)
!> \param do_backup if the BACKUP_COPIES keyword should be added to allow for backup
!> \author fawzi
! **************************************************************************************************
   SUBROUTINE cp_print_key_section_create(print_key_section, location, name, description, &
                                          print_level, each_iter_names, each_iter_values, add_last, filename, &
                                          common_iter_levels, citations, unit_str, do_backup)
      TYPE(section_type), POINTER                        :: print_key_section
      CHARACTER(len=*), INTENT(IN)                       :: location, name, description
      INTEGER, INTENT(IN), OPTIONAL                      :: print_level
      CHARACTER(LEN=*), DIMENSION(:), INTENT(IN), &
         OPTIONAL                                        :: each_iter_names
      INTEGER, DIMENSION(:), INTENT(IN), OPTIONAL        :: each_iter_values
      INTEGER, INTENT(IN), OPTIONAL                      :: add_last
      CHARACTER(LEN=*), INTENT(IN), OPTIONAL             :: filename
      INTEGER, INTENT(IN), OPTIONAL                      :: common_iter_levels
      INTEGER, DIMENSION(:), OPTIONAL                    :: citations
      CHARACTER(LEN=*), INTENT(IN), OPTIONAL             :: unit_str
      LOGICAL, OPTIONAL                                  :: do_backup
 
      CHARACTER(len=default_path_length)                 :: my_filename
      INTEGER                                            :: i_each, i_iter, my_add_last, &
                                                            my_comm_iter_levels, my_print_level, &
                                                            my_value
      LOGICAL                                            :: check, ext_each, my_do_backup
      TYPE(keyword_type), POINTER                        :: keyword
      TYPE(section_type), POINTER                        :: subsection
 
      cpassert(.NOT. ASSOCIATED(print_key_section))
      my_print_level = debug_print_level
      IF (PRESENT(print_level)) my_print_level = print_level
      my_do_backup = .false.
      IF (PRESENT(do_backup)) my_do_backup = do_backup
 
      CALL section_create(print_key_section, location=location, name=name, description=description, &
                          n_keywords=2, n_subsections=0, repeats=.false., &
                          citations=citations)
 
      NULLIFY (keyword, subsection)
      CALL keyword_create(keyword, __location__, name="_SECTION_PARAMETERS_", &
                          description="Level starting at which this property is printed. "// &
                          "Printing is activated when the GLOBAL/PRINT_LEVEL of a task is "// &
                          "higher than or equal to the level as specified here; to override "// &
                          "this comparison, use ON to always print or OFF to never print. "// &
                          "Explicitly giving the section without a level or ON or OFF is "// &
                          "treated as if SILENT is specified, whereas omitting the section "// &
                          "is treated implicitly using the default value.", &
                          usage="silent", &
                          default_i_val=my_print_level, lone_keyword_i_val=silent_print_level, &
                          enum_c_vals=s2a("on", "off", "silent", "low", "medium", "high", "debug"), &
                          enum_i_vals=[silent_print_level - 1, debug_print_level + 1, &
                                       silent_print_level, low_print_level, &
                                       medium_print_level, high_print_level, debug_print_level])
      CALL section_add_keyword(print_key_section, keyword)
      CALL keyword_release(keyword)
 
      CALL keyword_create(keyword, __location__, name="__CONTROL_VAL", &
                          description=' hidden parameter that controls storage, printing,...'// &
                          ' of the print_key', &
                          default_i_val=cp_out_default)
      CALL section_add_keyword(print_key_section, keyword)
      CALL keyword_release(keyword)
 
      CALL section_create(subsection, __location__, name="EACH", &
                          description="This section specifies how often this property is printed. "// &
                          "Each keyword inside this section is mapping to a specific iteration level and "// &
                          "the value of each of these keywords is matched with the iteration level during "// &
                          "the calculation. A value of 0 or negative turns off printing for the iteration "// &
                          "level. How to handle the last iteration is treated separately in the ADD_LAST "// &
                          "keyword outside of this section; each iteration level might print the last "// &
                          "iteration even if the corresponding value is set to 0 or negative. "// &
                          "If an iteration level is specified that is not present in the flow of "// &
                          "the calculation, it is just ignored; switch GLOBAL/ITER_LEVEL_VERBOSITY "// &
                          "to NOTICE or STACK to print information about existing iteration levels.", &
                          n_keywords=2, n_subsections=0, repeats=.false., &
                          citations=citations)
 
      ! Enforce the presence or absence of both.. or give an error
      check = (PRESENT(each_iter_names)) .EQV. (PRESENT(each_iter_values))
      cpassert(check)
      ext_each = (PRESENT(each_iter_names)) .AND. (PRESENT(each_iter_values))
 
      DO i_each = 1, SIZE(each_possible_labels)
         my_value = 1
         IF (ext_each) THEN
            check = sum(index(each_iter_names, each_possible_labels(i_each))) <= 1
            cpassert(check)
            DO i_iter = 1, SIZE(each_iter_names)
               IF (index(trim(each_iter_names(i_iter)), trim(each_possible_labels(i_each))) /= 0) THEN
                  my_value = each_iter_values(i_iter)
               END IF
            END DO
         END IF
         CALL keyword_create(keyword, __location__, name=trim(each_possible_labels(i_each)), &
                             description=trim(each_desc_labels(i_each)), &
                             usage=trim(each_possible_labels(i_each))//" <INTEGER>", &
                             default_i_val=my_value)
         CALL section_add_keyword(subsection, keyword)
         CALL keyword_release(keyword)
      END DO
      CALL section_add_subsection(print_key_section, subsection)
      CALL section_release(subsection)
 
      my_add_last = add_last_no
      IF (PRESENT(add_last)) THEN
         my_add_last = add_last
      END IF
      CALL keyword_create(keyword, __location__, name="ADD_LAST", &
                          description="If the last iteration should be added, and if it "// &
                          "should be marked symbolically (with lowercase letter l) or with "// &
                          "the iteration number. "// &
                          "Not every iteration level is able to identify the last iteration "// &
                          "early enough to be able to output. When this keyword is activated "// &
                          "all iteration levels are checked for the last iteration step.", &
                          usage="ADD_LAST (NO|NUMERIC|SYMBOLIC)", &
                          enum_c_vals=s2a("no", "numeric", "symbolic"), &
                          enum_i_vals=[add_last_no, add_last_numeric, add_last_symbolic], &
                          enum_desc=s2a("Do not mark last iteration specifically", &
                                        "Mark last iteration with its iteration number", &
                                        "Mark last iteration with lowercase letter l"), &
                          default_i_val=my_add_last)
      CALL section_add_keyword(print_key_section, keyword)
      CALL keyword_release(keyword)
 
      my_comm_iter_levels = 0
      IF (PRESENT(common_iter_levels)) my_comm_iter_levels = common_iter_levels
      CALL keyword_create(keyword, __location__, name="COMMON_ITERATION_LEVELS", &
                          description="How many iteration levels should be written "// &
                          "in the same file (no extra information about the actual "// &
                          "iteration level is written to the file). Set to 0 to use "// &
                          "the current iteration level, 1 to use the next level, ..., "// &
                          "in the stack of iteration levels (printed by setting the "// &
                          "GLOBAL/ITER_LEVEL_VERBOSITY to STACK).", &
                          usage="COMMON_ITERATION_LEVELS <INTEGER>", &
                          default_i_val=my_comm_iter_levels)
      CALL section_add_keyword(print_key_section, keyword)
      CALL keyword_release(keyword)
 
      my_filename = ""
      IF (PRESENT(filename)) my_filename = filename
      CALL keyword_create(keyword, __location__, name="FILENAME", &
                          description="Controls part of the filename for output."//newline//newline// &
                          "* Use `__STD_OUT__` (exactly as written here) for the screen or "// &
                          "standard logger (stdout)."//newline// &
                          "* Use `filename` to obtain `projectname-filename` with "// &
                          "`projectname` defined by &GLOBAL/PROJECT_NAME."//newline// &
                          "* Use `./filename` to get a filename with a middle name (if present), "// &
                          "iteration numbers and extension always added to the filename."//newline// &
                          "* Use `=filename` to get `filename` always exactly as typed, but "// &
                          "please note that this can lead to clashes of filenames.", &
                          usage="FILENAME ./filename ", &
                          default_lc_val=my_filename)
      CALL section_add_keyword(print_key_section, keyword)
      CALL keyword_release(keyword)
 
      CALL keyword_create(keyword, __location__, name="LOG_PRINT_KEY", &
                          description="This keywords enables the logger for the print_key (a message is printed on "// &
                          "screen everytime data, controlled by this print_key, are written)", &
                          usage="LOG_PRINT_KEY <LOGICAL>", default_l_val=.false., lone_keyword_l_val=.true.)
      CALL section_add_keyword(print_key_section, keyword)
      CALL keyword_release(keyword)
 
      IF (PRESENT(unit_str)) THEN
         CALL keyword_create(keyword, __location__, name="UNIT", &
                             description='Specify the unit of measurement for the quantity in output. '// &
                             "All available CP2K units can be used.", &
                             usage="UNIT angstrom", default_c_val=trim(unit_str))
         CALL section_add_keyword(print_key_section, keyword)
         CALL keyword_release(keyword)
      END IF
 
      IF (my_do_backup) THEN
         CALL keyword_create(keyword, __location__, name="BACKUP_COPIES", &
                             description="Specifies the maximum number of backup copies preserved "// &
                             "when iterations will repeatedly print to the same filename. If set to "// &
                             "N > 0, the files will be automatically rotated by appending a suffix: "// &
                             "the most recent print is `{filename}` (defined by FILENAME keyword), "// &
                             "the last one is moved to `{filename}.bak-1`, the second to last moved "// &
                             "to `{filename}.bak-2`, ..., up to `{filename}.bak-N`. Set to 0 to "// &
                             "disable backup preservation and rewrite always the same `{filename}`.", &
                             usage="BACKUP_COPIES {int}", default_i_val=1)
         CALL section_add_keyword(print_key_section, keyword)
         CALL keyword_release(keyword)
      END IF
   END SUBROUTINE cp_print_key_section_create
 
! **************************************************************************************************
!> \brief returns what should be done with the given property
!>      if btest(res,cp_p_store) then the property should be stored in memory
!>      if btest(res,cp_p_file) then the property should be print ed to a file
!>      if res==0 then nothing should be done
!> \param iteration_info information about the actual iteration level
!> \param basis_section section that contains the printkey
!> \param print_key_path path to the printkey- "%" between sections, and
!>        optionally a "/" and a logical flag to check). Might be empty.
!> \param used_print_key here the print_key that was used is returned
!> \param first_time if it ist the first time that an output is written
!>        (not fully correct, but most of the time)
!> \return ...
!> \author fawzi
!> \note
!>      not all the propreties support can be stored
! **************************************************************************************************
   FUNCTION cp_print_key_should_output(iteration_info, basis_section, &
                                       print_key_path, used_print_key, first_time) &
      result(res)
      TYPE(cp_iteration_info_type), INTENT(IN)           :: iteration_info
      TYPE(section_vals_type), INTENT(IN), TARGET        :: basis_section
      CHARACTER(len=*), INTENT(IN), OPTIONAL             :: print_key_path
      TYPE(section_vals_type), INTENT(INOUT), OPTIONAL, &
         POINTER                                         :: used_print_key
      LOGICAL, INTENT(OUT), OPTIONAL                     :: first_time
      INTEGER                                            :: res
 
      INTEGER                                            :: end_str, my_control_val, to_path
      LOGICAL                                            :: flags, is_iter, is_on
      TYPE(section_vals_type), POINTER                   :: print_key
 
      res = 0
      IF (PRESENT(first_time)) first_time = .false.
      cpassert(basis_section%ref_count > 0)
      IF (PRESENT(used_print_key)) NULLIFY (used_print_key)
 
      IF (PRESENT(print_key_path)) THEN
         end_str = len_trim(print_key_path)
         to_path = index(print_key_path, "/")
         IF (to_path < 1) THEN
            to_path = end_str + 1
         END IF
 
         IF (to_path > 1) THEN
            print_key => section_vals_get_subs_vals(basis_section, &
                                                    print_key_path(1:(to_path - 1)))
         ELSE
            print_key => basis_section
         END IF
         cpassert(ASSOCIATED(print_key))
         cpassert(print_key%ref_count > 0)
         IF (to_path + 1 < end_str) THEN
            CALL section_vals_val_get(print_key, print_key_path((to_path + 1):end_str), &
                                      l_val=flags)
         ELSE
            flags = .true.
         END IF
      ELSE
         print_key => basis_section
         flags = .true.
      END IF
      IF (PRESENT(used_print_key)) used_print_key => print_key
 
      IF (.NOT. flags) RETURN
 
      CALL section_vals_val_get(print_key, "__CONTROL_VAL", &
                                i_val=my_control_val)
      is_on = cp_printkey_is_on(iteration_info, print_key)
 
      ! a shortcut for most common case
      IF (my_control_val == cp_out_default .AND. .NOT. is_on) RETURN
 
      is_iter = cp_printkey_is_iter(iteration_info, print_key, first_time=first_time)
 
      IF (btest(my_control_val, cp_p_store)) THEN
         res = ibset(res, cp_p_store)
      ELSE IF (btest(my_control_val, cp_p_store_if) .AND. is_iter .AND. is_on) THEN
         res = ibset(res, cp_p_store)
      ELSE IF (btest(my_control_val, cp_p_store_each) .AND. is_iter) THEN
         res = ibset(res, cp_p_store)
      END IF
 
      IF (btest(my_control_val, cp_p_file)) THEN
         res = ibset(res, cp_p_file)
      ELSE IF (btest(my_control_val, cp_p_file_if) .AND. is_iter .AND. is_on) THEN
         res = ibset(res, cp_p_file)
      ELSE IF (btest(my_control_val, cp_p_file_each) .AND. is_iter) THEN
         res = ibset(res, cp_p_file)
      END IF
      IF (btest(my_control_val, cp_p_calc) .OR. res /= 0) THEN
         res = ibset(res, cp_p_calc)
      END IF
   END FUNCTION cp_print_key_should_output
 
! **************************************************************************************************
!> \brief returns true if the printlevel activates this printkey
!>      does not look if this iteration it should be printed
!> \param iteration_info information about the actual iteration level
!> \param print_key the section values of the key to be printed
!> \return ...
!> \author fawzi
! **************************************************************************************************
   FUNCTION cp_printkey_is_on(iteration_info, print_key) RESULT(res)
      TYPE(cp_iteration_info_type), INTENT(IN)           :: iteration_info
      TYPE(section_vals_type), POINTER                   :: print_key
      LOGICAL                                            :: res
 
      INTEGER                                            :: print_level
 
      cpassert(iteration_info%ref_count > 0)
      IF (.NOT. ASSOCIATED(print_key)) THEN
         res = (iteration_info%print_level > debug_print_level)
      ELSE
         cpassert(print_key%ref_count > 0)
         CALL section_vals_val_get(print_key, "_SECTION_PARAMETERS_", i_val=print_level)
         res = iteration_info%print_level >= print_level
      END IF
   END FUNCTION cp_printkey_is_on
 
! **************************************************************************************************
!> \brief returns if the actual iteration matches those selected by the
!>      given printkey. Does not check it the prinkey is active (at the
!>      actual print_level)
!> \param iteration_info information about the actual iteration level
!> \param print_key the section values of the key to be printed
!> \param first_time returns if it is the first time that output is written
!>        (not fully correct, but most of the time)
!> \return ...
!> \author fawzi
! **************************************************************************************************
   FUNCTION cp_printkey_is_iter(iteration_info, print_key, first_time) &
      result(res)
      TYPE(cp_iteration_info_type), INTENT(IN)           :: iteration_info
      TYPE(section_vals_type), POINTER                   :: print_key
      LOGICAL, INTENT(OUT), OPTIONAL                     :: first_time
      LOGICAL                                            :: res
 
      INTEGER                                            :: add_last, ilevel, iter_nr, ival
      LOGICAL                                            :: first, level_passed
 
      cpassert(iteration_info%ref_count > 0)
      IF (.NOT. ASSOCIATED(print_key)) THEN
         res = (iteration_info%print_level > debug_print_level)
         first = all(iteration_info%iteration(1:iteration_info%n_rlevel) == 1)
      ELSE
         cpassert(print_key%ref_count > 0)
         res = .false.
         first = .false.
         CALL section_vals_val_get(print_key, "ADD_LAST", i_val=add_last)
         res = .true.
         first = .true.
         DO ilevel = 1, iteration_info%n_rlevel
            level_passed = .false.
            CALL section_vals_val_get(print_key, "EACH%"//trim(iteration_info%level_name(ilevel)), &
                                      i_val=ival)
            IF (ival > 0) THEN
               iter_nr = iteration_info%iteration(ilevel)
               IF (iter_nr/ival > 1) first = .false.
               IF (modulo(iter_nr, ival) == 0) THEN
                  level_passed = .true.
               END IF
            END IF
            IF (add_last == add_last_numeric .OR. add_last == add_last_symbolic) THEN
               IF (iteration_info%last_iter(ilevel)) THEN
                  level_passed = .true.
               END IF
            END IF
            IF (.NOT. level_passed) res = .false.
         END DO
      END IF
      first = first .AND. res
      IF (PRESENT(first_time)) first_time = first
   END FUNCTION cp_printkey_is_iter
 
! **************************************************************************************************
!> \brief returns the iteration string, a string that is useful to create
!>      unique filenames (once you trim it)
!> \param iter_info the iteration info from where to take the iteration
!>        number
!> \param print_key the print key to optionally show the last iteration
!>        symbolically
!> \param for_file if the string is to be used for file generation
!>        (and should consequently ignore some iteration levels depending
!>        on COMMON_ITERATION_LEVELS).
!>        Defaults to false.
!> \return ...
!> \author fawzi
!> \note
!>      If the root level is 1 removes it
! **************************************************************************************************
   FUNCTION cp_iter_string(iter_info, print_key, for_file) RESULT(res)
      TYPE(cp_iteration_info_type), POINTER              :: iter_info
      TYPE(section_vals_type), OPTIONAL, POINTER         :: print_key
      LOGICAL, INTENT(IN), OPTIONAL                      :: for_file
      CHARACTER(len=default_string_length)               :: res
 
      INTEGER                                            :: add_last, c_i_level, ilevel, n_rlevel, &
                                                            s_level
      LOGICAL                                            :: my_for_file
      TYPE(section_vals_type), POINTER                   :: my_print_key
 
      res = ""
      my_for_file = .false.
      IF (PRESENT(for_file)) my_for_file = for_file
      cpassert(ASSOCIATED(iter_info))
      cpassert(iter_info%ref_count > 0)
      NULLIFY (my_print_key)
      IF (PRESENT(print_key)) my_print_key => print_key
      s_level = 1
      IF (ASSOCIATED(my_print_key)) THEN
         CALL section_vals_val_get(my_print_key, "ADD_LAST", i_val=add_last)
         CALL section_vals_val_get(my_print_key, "COMMON_ITERATION_LEVELS", i_val=c_i_level)
         n_rlevel = iter_info%n_rlevel
         IF (my_for_file) n_rlevel = min(n_rlevel, max(0, n_rlevel - c_i_level))
         DO ilevel = s_level, n_rlevel
            IF (iter_info%last_iter(ilevel)) THEN
               IF (add_last == add_last_symbolic) THEN
                  WRITE (res(9*ilevel - 8:9*ilevel), "('l_')")
               ELSE
                  WRITE (res(9*ilevel - 8:9*ilevel), "(i8,'_')") iter_info%iteration(ilevel)
               END IF
            ELSE
               WRITE (res(9*ilevel - 8:9*ilevel), "(i8,'_')") iter_info%iteration(ilevel)
            END IF
         END DO
      ELSE
         DO ilevel = s_level, iter_info%n_rlevel
            WRITE (res(9*ilevel - 8:9*ilevel), "(i8,'_')") iter_info%iteration(ilevel)
         END DO
      END IF
      CALL compress(res, .true.)
      IF (len_trim(res) > 0) THEN
         res(len_trim(res):len_trim(res)) = " "
      END IF
   END FUNCTION cp_iter_string
 
! **************************************************************************************************
!> \brief adds one to the actual iteration
!> \param iteration_info the iteration info to update
!> \param last if this iteration is the last one (defaults to false)
!> \param iter_nr ...
!> \param increment ...
!> \param iter_nr_out ...
!> \author fawzi
!> \note
!>      this is supposed to be called at the beginning of each iteration
! **************************************************************************************************
   SUBROUTINE cp_iterate(iteration_info, last, iter_nr, increment, iter_nr_out)
      TYPE(cp_iteration_info_type), POINTER              :: iteration_info
      LOGICAL, INTENT(IN), OPTIONAL                      :: last
      INTEGER, INTENT(IN), OPTIONAL                      :: iter_nr, increment
      INTEGER, INTENT(OUT), OPTIONAL                     :: iter_nr_out
 
      INTEGER                                            :: my_increment
      LOGICAL                                            :: my_last
 
      my_last = .false.
      my_increment = 1
      IF (PRESENT(last)) my_last = last
      IF (PRESENT(increment)) my_increment = increment
      IF (PRESENT(iter_nr_out)) iter_nr_out = -1
 
      cpassert(ASSOCIATED(iteration_info))
      cpassert(iteration_info%ref_count > 0)
      IF (PRESENT(iter_nr)) THEN
         iteration_info%iteration(iteration_info%n_rlevel) = iter_nr
      ELSE
         iteration_info%iteration(iteration_info%n_rlevel) = &
            iteration_info%iteration(iteration_info%n_rlevel) + my_increment
      END IF
      ! If requested provide the value of the iteration level
      IF (PRESENT(iter_nr_out)) iter_nr_out = iteration_info%iteration(iteration_info%n_rlevel)
 
      ! Possibly setup the LAST flag
      iteration_info%last_iter(iteration_info%n_rlevel) = my_last
   END SUBROUTINE cp_iterate
 
! **************************************************************************************************
!> \brief Return the index of an iteration level by its name.
!> \param iteration_info the iteration info to query
!> \param level_name     level name to query.
!> \return iteration level index or 0 if there is no such level
!> \author Sergey Chulkov
! **************************************************************************************************
   FUNCTION cp_get_iter_level_by_name(iteration_info, level_name) RESULT(rlevel)
      TYPE(cp_iteration_info_type), INTENT(IN), POINTER  :: iteration_info
      CHARACTER(LEN=*), INTENT(IN)                       :: level_name
      INTEGER                                            :: rlevel
 
      cpassert(ASSOCIATED(iteration_info))
      cpassert(iteration_info%ref_count > 0)
      DO rlevel = iteration_info%n_rlevel, 1, -1
         IF (iteration_info%level_name(rlevel) == level_name) EXIT
      END DO
 
   END FUNCTION cp_get_iter_level_by_name
 
! **************************************************************************************************
!> \brief Return the current iteration number at a given level.
!> \param iteration_info the iteration info to query
!> \param rlevel         index of the iteration level. Use the level on top of the stack,
!>                       if it is not given
!> \param iter_nr        iteration number [out]
!> \param last_iter      last iteration flag [out]
!> \author Sergey Chulkov
! **************************************************************************************************
   SUBROUTINE cp_get_iter_nr(iteration_info, rlevel, iter_nr, last_iter)
      TYPE(cp_iteration_info_type), INTENT(IN), POINTER  :: iteration_info
      INTEGER, INTENT(IN), OPTIONAL                      :: rlevel
      INTEGER, INTENT(OUT), OPTIONAL                     :: iter_nr
      LOGICAL, INTENT(OUT), OPTIONAL                     :: last_iter
 
      INTEGER                                            :: ilevel
 
      cpassert(ASSOCIATED(iteration_info))
      cpassert(iteration_info%ref_count > 0)
      IF (PRESENT(rlevel)) THEN
         cpassert(rlevel > 0 .AND. rlevel <= iteration_info%n_rlevel)
         ilevel = rlevel
      ELSE
         ilevel = iteration_info%n_rlevel
      END IF
 
      IF (PRESENT(iter_nr)) iter_nr = iteration_info%iteration(ilevel)
      IF (PRESENT(last_iter)) last_iter = iteration_info%last_iter(ilevel)
   END SUBROUTINE cp_get_iter_nr
 
! **************************************************************************************************
!> \brief Adds an iteration level
!> \param logger the logger with the iteration info to which an iteration level has
!>        to be added
!> \param level_name the name of this level, for pretty printing only, right now
!> \param n_rlevel_new number of iteration levels after this call
!> \author fawzi
! **************************************************************************************************
   SUBROUTINE cp_add_iter_level(logger, level_name, n_rlevel_new)
      TYPE(cp_logger_type), POINTER                      :: logger
      CHARACTER(LEN=*), INTENT(IN)                       :: level_name
      INTEGER, INTENT(OUT), OPTIONAL                     :: n_rlevel_new
 
      INTEGER                                            :: i
      LOGICAL                                            :: found
      TYPE(cp_iteration_info_type), POINTER              :: iteration_info
 
      cpassert(ASSOCIATED(logger))
      iteration_info => logger%iter_info
      cpassert(ASSOCIATED(iteration_info))
      cpassert(iteration_info%ref_count > 0)
      found = .false.
      DO i = 1, SIZE(each_possible_labels)
         IF (trim(level_name) == trim(each_possible_labels(i))) THEN
            found = .true.
            EXIT
         END IF
      END DO
      IF (found) THEN
         CALL cp_iteration_info_retain(iteration_info)
         iteration_info%n_rlevel = iteration_info%n_rlevel + 1
         CALL reallocate(iteration_info%iteration, 1, iteration_info%n_rlevel)
         CALL reallocate(iteration_info%level_name, 1, iteration_info%n_rlevel)
         CALL reallocate(iteration_info%last_iter, 1, iteration_info%n_rlevel)
         iteration_info%iteration(iteration_info%n_rlevel) = 0
         iteration_info%level_name(iteration_info%n_rlevel) = level_name
         iteration_info%last_iter(iteration_info%n_rlevel) = .false.
         IF (PRESENT(n_rlevel_new)) n_rlevel_new = iteration_info%n_rlevel
         CALL cp_iter_level_print(logger, "A")
      ELSE
         CALL cp_abort(__location__, &
                       "Trying to create an iteration level ("//trim(level_name)//") not defined. "// &
                       "Please update the module: cp_iter_types.")
      END IF
 
   END SUBROUTINE cp_add_iter_level
 
! **************************************************************************************************
!> \brief Removes an iteration level
!> \param logger the logger with the iteration info to which an iteration level has
!>        to be removed
!> \param level_name level_name to be destroyed (if does not match gives an error)
!> \param n_rlevel_att iteration level before the call (to do some checks)
!> \author fawzi
! **************************************************************************************************
   SUBROUTINE cp_rm_iter_level(logger, level_name, n_rlevel_att)
      TYPE(cp_logger_type), POINTER                      :: logger
      CHARACTER(LEN=*), INTENT(IN)                       :: level_name
      INTEGER, INTENT(IN), OPTIONAL                      :: n_rlevel_att
 
      LOGICAL                                            :: check
      TYPE(cp_iteration_info_type), POINTER              :: iteration_info
 
      cpassert(ASSOCIATED(logger))
      iteration_info => logger%iter_info
      cpassert(ASSOCIATED(iteration_info))
      cpassert(iteration_info%ref_count > 0)
      IF (PRESENT(n_rlevel_att)) THEN
         cpassert(n_rlevel_att == iteration_info%n_rlevel)
      END IF
      CALL cp_iter_level_print(logger, "R")
      CALL cp_iteration_info_release(iteration_info)
      ! This check that the iteration levels are consistently created and destroyed..
      ! Never remove this check..
      check = iteration_info%level_name(iteration_info%n_rlevel) == level_name
      cpassert(check)
      iteration_info%n_rlevel = iteration_info%n_rlevel - 1
      CALL reallocate(iteration_info%iteration, 1, iteration_info%n_rlevel)
      CALL reallocate(iteration_info%level_name, 1, iteration_info%n_rlevel)
      CALL reallocate(iteration_info%last_iter, 1, iteration_info%n_rlevel)
   END SUBROUTINE cp_rm_iter_level
 
! **************************************************************************************************
!> \brief Print information entering or exiting an iteration level
!> \param logger the logger with iteration info and para_env
!> \param direction entering (A) or exiting (R) the iteration level
!> \param local if the unit should be local to this task
!> \author Zilong HE
! **************************************************************************************************
   SUBROUTINE cp_iter_level_print(logger, direction, local)
      TYPE(cp_logger_type), POINTER                      :: logger
      CHARACTER(LEN=1), INTENT(IN)                       :: direction
      LOGICAL, INTENT(IN), OPTIONAL                      :: local
 
      INTEGER, PARAMETER                                 :: min_iter_level = 2
 
      CHARACTER(LEN=:), ALLOCATABLE                      :: level_name
      INTEGER                                            :: iter_nr, rlevel, unit_nr
      LOGICAL                                            :: my_local
      TYPE(cp_iteration_info_type), POINTER              :: iteration_info
 
      ! min_iter_level = 2 is to skip iteration_info%level_name(1)
      ! which corresponds to a fictitious __ROOT__ level added in
      ! the init_cp2k subroutine. The level_name should be one of
      ! the list each_possible_labels; the following WRITE format
      ! assumes implicitly a maximum length of 27 characters.
 
      iteration_info => logger%iter_info
      my_local = .false.
      IF (PRESENT(local)) my_local = local
      IF (my_local .OR. logger%para_env%is_source()) THEN
         IF (iteration_info%iter_print >= iter_silent) THEN
            rlevel = iteration_info%n_rlevel
            cpassert(rlevel > 0)
            level_name = trim(adjustl(iteration_info%level_name(rlevel)))
            CALL cp_get_iter_nr(iteration_info, rlevel, iter_nr)
            IF (iteration_info%iter_print > iter_silent) THEN
               unit_nr = cp_logger_get_unit_nr(logger, local=my_local)
               IF (unit_nr > 0) THEN
                  WRITE (unit=unit_nr, fmt="()")
                  ! The current iteration level
                  SELECT CASE (direction)
                  CASE ("A") ! After adding level in cp_add_iter_level
                     WRITE (unit=unit_nr, fmt="(T2,A,T37,I3,T41,A,T73,I8)") &
                        "ITER_LV| >>>>>>>> Entering level +", rlevel, "[ "//level_name//" ]", iter_nr
                  CASE ("R") ! Before removing level in cp_rm_iter_level
                     WRITE (unit=unit_nr, fmt="(T2,A,T37,I3,T41,A,T73,I8)") &
                        "ITER_LV| <<<<<<<<  Exiting level -", rlevel, "[ "//level_name//" ]", iter_nr
                  CASE DEFAULT
                     CALL cp_abort(__location__, &
                                   "Only entering (A) or exiting (R) an iteration level "// &
                                   "can have a message printed.")
                  END SELECT
                  ! The rest of stack of iteration levels
                  IF (iteration_info%iter_print > iter_notice) THEN
                     DO WHILE (rlevel > min_iter_level)
                        rlevel = rlevel - 1
                        level_name = trim(adjustl(iteration_info%level_name(rlevel)))
                        CALL cp_get_iter_nr(iteration_info, rlevel, iter_nr)
                        WRITE (unit=unit_nr, fmt="(T2,A,T37,I3,T41,A,T73,I8)") &
                           "ITER_LV|                         *", rlevel, "[ "//level_name//" ]", iter_nr
                     END DO
                  END IF
                  WRITE (unit=unit_nr, fmt="()")
               END IF
            END IF
         ELSE
            CALL cp_warn(__location__, &
                         "An iteration level has been added to or removed from a logger "// &
                         "that does not receive the GLOBAL%ITER_LEVEL_VERBOSITY setting.")
         END IF
      END IF
 
   END SUBROUTINE cp_iter_level_print
 
! **************************************************************************************************
!> \brief Utility function that returns a unit number to write the print key.
!>     Might open a file with a unique filename, generated from
!>     the print_key name and iteration info.
!>
!>     Normally a valid unit (>0) is returned only if cp_print_key_should_output
!>     says that the print_key should be printed, and if the unit is global
!>     only the io node has a valid unit.
!>     So in many cases you can decide if you should print just checking if
!>     the returned units is bigger than 0.
!>
!>     IMPORTANT you should call cp_finished_output when an iteration output is
!>     finished (to immediately close the file that might have been opened)
!> \param logger the logger for the parallel environment, iteration info
!>        and filename generation
!> \param print_key ...
!> \param middle_name name to be added to the generated filename, useful when
!>        print_key activates different distinct outputs, to be able to
!>        distinguish them
!> \param extension extension to be applied to the filename (including the ".")
!> \param my_local if the unit should be local to this task, or global to the
!>        program (defaults to false).
!> \return ...
!> \author Fawzi Mohamed
! **************************************************************************************************
   FUNCTION cp_print_key_generate_filename(logger, print_key, middle_name, extension, &
                                           my_local) RESULT(filename)
      TYPE(cp_logger_type), POINTER                      :: logger
      TYPE(section_vals_type), POINTER                   :: print_key
      CHARACTER(len=*), INTENT(IN), OPTIONAL             :: middle_name
      CHARACTER(len=*), INTENT(IN)                       :: extension
      LOGICAL, INTENT(IN)                                :: my_local
      CHARACTER(len=default_path_length)                 :: filename
 
      CHARACTER(len=default_path_length)                 :: outname, outpath, postfix, root
      CHARACTER(len=default_string_length)               :: my_middle_name
      INTEGER                                            :: my_ind1, my_ind2
      LOGICAL                                            :: has_root
 
      CALL section_vals_val_get(print_key, "FILENAME", c_val=outpath)
      IF (outpath(1:1) == '=') THEN
         cpassert(len(outpath) - 1 <= len(filename))
         filename = outpath(2:)
         RETURN
      END IF
      IF (outpath == "__STD_OUT__") outpath = ""
      outname = outpath
      has_root = .false.
      my_ind1 = index(outpath, "/")
      my_ind2 = len_trim(outpath)
      IF (my_ind1 /= 0) THEN
         has_root = .true.
         DO WHILE (index(outpath(my_ind1 + 1:my_ind2), "/") /= 0)
            my_ind1 = index(outpath(my_ind1 + 1:my_ind2), "/") + my_ind1
         END DO
         IF (my_ind1 == my_ind2) THEN
            outname = ""
         ELSE
            outname = outpath(my_ind1 + 1:my_ind2)
         END IF
      END IF
 
      IF (PRESENT(middle_name)) THEN
         IF (outname /= "") THEN
            my_middle_name = "-"//trim(outname)//"-"//middle_name
         ELSE
            my_middle_name = "-"//middle_name
         END IF
      ELSE
         IF (outname /= "") THEN
            my_middle_name = "-"//trim(outname)
         ELSE
            my_middle_name = ""
         END IF
      END IF
 
      IF (.NOT. has_root) THEN
         root = trim(logger%iter_info%project_name)//trim(my_middle_name)
      ELSE IF (outname == "") THEN
         root = outpath(1:my_ind1)//trim(logger%iter_info%project_name)//trim(my_middle_name)
      ELSE
         root = outpath(1:my_ind1)//my_middle_name(2:len_trim(my_middle_name))
      END IF
 
      ! use the cp_iter_string as a postfix
      postfix = "-"//trim(cp_iter_string(logger%iter_info, print_key=print_key, for_file=.true.))
      IF (trim(postfix) == "-") postfix = ""
 
      ! and add the extension
      postfix = trim(postfix)//extension
      ! and let the logger generate the filename
      CALL cp_logger_generate_filename(logger, res=filename, &
                                       root=root, postfix=postfix, local=my_local)
 
   END FUNCTION cp_print_key_generate_filename
 
! **************************************************************************************************
!> \brief ...
!> \param logger ...
!> \param basis_section ...
!> \param print_key_path ...
!> \param extension ...
!> \param middle_name ...
!> \param local ...
!> \param log_filename ...
!> \param ignore_should_output ...
!> \param file_form ...
!> \param file_position ...
!> \param file_action ...
!> \param file_status ...
!> \param do_backup ...
!> \param on_file ...
!> \param is_new_file true if this rank created a new (or rewound) file, false otherwise
!> \param mpi_io True if the file should be opened in parallel on all processors belonging to
!>               the communicator group. Automatically disabled if the file form or access mode
!>               is unsuitable for MPI IO. Return value indicates whether MPI was actually used
!>               and therefore the flag must also be passed to the file closing directive.
!> \param fout   Name of the actual file where the output will be written. Needed mainly for MPI IO
!>               because inquiring the filename from the MPI filehandle does not work across
!>               all MPI libraries.
!> \param file_access Fortran access mode (SEQUENTIAL by default, or STREAM); unused with MPI I/O
!> \return ...
! **************************************************************************************************
   FUNCTION cp_print_key_unit_nr(logger, basis_section, print_key_path, extension, &
                                 middle_name, local, log_filename, ignore_should_output, file_form, file_position, &
                                 file_action, file_status, do_backup, on_file, is_new_file, mpi_io, &
                                 fout, file_access) RESULT(res)
      TYPE(cp_logger_type), POINTER                      :: logger
      TYPE(section_vals_type), INTENT(IN)                :: basis_section
      CHARACTER(len=*), INTENT(IN), OPTIONAL             :: print_key_path
      CHARACTER(len=*), INTENT(IN)                       :: extension
      CHARACTER(len=*), INTENT(IN), OPTIONAL             :: middle_name
      LOGICAL, INTENT(IN), OPTIONAL                      :: local, log_filename, ignore_should_output
      CHARACTER(len=*), INTENT(IN), OPTIONAL             :: file_form, file_position, file_action, &
                                                            file_status
      LOGICAL, INTENT(IN), OPTIONAL                      :: do_backup, on_file
      LOGICAL, INTENT(OUT), OPTIONAL                     :: is_new_file
      LOGICAL, INTENT(INOUT), OPTIONAL                   :: mpi_io
      CHARACTER(len=default_path_length), INTENT(OUT), &
         OPTIONAL                                        :: fout
      CHARACTER(len=*), INTENT(IN), OPTIONAL             :: file_access
      INTEGER                                            :: res
 
      CHARACTER(len=default_path_length)                 :: filename, filename_bak, filename_bak_1, &
                                                            filename_bak_2
      CHARACTER(len=default_string_length)               :: my_file_action, my_file_form, &
                                                            my_file_position, my_file_status, &
                                                            outpath
      INTEGER                                            :: c_i_level, f_backup_level, i, mpi_amode, &
                                                            my_backup_level, my_nbak, nbak, &
                                                            s_backup_level, unit_nr
      LOGICAL                                            :: do_log, found, my_do_backup, my_local, &
                                                            my_mpi_io, my_on_file, &
                                                            my_should_output, replace
      TYPE(cp_iteration_info_type), POINTER              :: iteration_info
      TYPE(mp_file_type)                                 :: mp_unit
      TYPE(section_vals_type), POINTER                   :: print_key
 
      my_local = .false.
      my_do_backup = .false.
      my_mpi_io = .false.
      replace = .false.
      found = .false.
      res = -1
      my_file_form = "FORMATTED"
      my_file_position = "APPEND"
      my_file_action = "WRITE"
      my_file_status = "UNKNOWN"
      my_on_file = .false.
      mpi_amode = 0
      IF (PRESENT(file_form)) my_file_form = file_form
      IF (PRESENT(file_position)) my_file_position = file_position
      IF (PRESENT(file_action)) my_file_action = file_action
      IF (PRESENT(file_status)) my_file_status = file_status
      IF (PRESENT(do_backup)) my_do_backup = do_backup
      IF (PRESENT(on_file)) my_on_file = on_file
      IF (PRESENT(local)) my_local = local
      IF (PRESENT(is_new_file)) is_new_file = .false.
      IF (PRESENT(mpi_io)) THEN
#if defined(__parallel)
         IF (cp_mpi_io_get() .AND. logger%para_env%num_pe > 1 .AND. mpi_io) THEN
            my_mpi_io = .true.
         ELSE
            my_mpi_io = .false.
         END IF
         IF (my_mpi_io) THEN
            CALL mp_file_get_amode(mpi_io, replace, mpi_amode, trim(my_file_form), &
                                   trim(my_file_action), trim(my_file_status), trim(my_file_position))
            replace = replace .AND. logger%para_env%is_source()
         END IF
#else
         my_mpi_io = .false.
#endif
         ! Set return value
         mpi_io = my_mpi_io
      END IF
      NULLIFY (print_key)
      cpassert(ASSOCIATED(logger))
      cpassert(basis_section%ref_count > 0)
      cpassert(logger%ref_count > 0)
      my_should_output = btest(cp_print_key_should_output(logger%iter_info, &
                                                          basis_section, print_key_path, used_print_key=print_key), cp_p_file)
      IF (PRESENT(ignore_should_output)) my_should_output = my_should_output .OR. ignore_should_output
      IF (.NOT. my_should_output) RETURN
      IF (my_local .OR. &
          logger%para_env%is_source() .OR. &
          my_mpi_io) THEN
 
         CALL section_vals_val_get(print_key, "FILENAME", c_val=outpath)
         IF (outpath == '__STD_OUT__' .AND. .NOT. my_on_file) THEN
            res = cp_logger_get_default_unit_nr(logger, local=my_local)
         ELSE
            !
            ! complex logic to build filename:
            !   1)  Try to avoid '--' and '-.'
            !   2)  If outPath contains '/' (as in ./filename) do not prepend the project_name
            !
            ! if it is actually a full path, use it as the root
            filename = cp_print_key_generate_filename(logger, print_key, middle_name, extension, &
                                                      my_local)
            ! Give back info about a possible existence of the file if required
            IF (PRESENT(is_new_file)) THEN
               INQUIRE (file=filename, exist=found)
               is_new_file = .NOT. found
               IF (my_file_position == "REWIND") is_new_file = .true.
            END IF
            ! Check is we have to log any operation performed on the file..
            do_log = .false.
            IF (PRESENT(log_filename)) THEN
               do_log = log_filename
            ELSE
               CALL section_vals_val_get(print_key, "LOG_PRINT_KEY", l_val=do_log)
            END IF
            ! If required do a backup
            IF (my_do_backup) THEN
               INQUIRE (file=filename, exist=found)
               CALL section_vals_val_get(print_key, "BACKUP_COPIES", i_val=nbak)
               IF (nbak /= 0) THEN
                  iteration_info => logger%iter_info
                  s_backup_level = 0
                  IF (ASSOCIATED(print_key%ibackup)) s_backup_level = SIZE(print_key%ibackup)
                  CALL section_vals_val_get(print_key, "COMMON_ITERATION_LEVELS", i_val=c_i_level)
                  my_backup_level = max(1, iteration_info%n_rlevel - c_i_level + 1)
                  f_backup_level = max(s_backup_level, my_backup_level)
                  IF (f_backup_level > s_backup_level) THEN
                     CALL reallocate(print_key%ibackup, 1, f_backup_level)
                     DO i = s_backup_level + 1, f_backup_level
                        print_key%ibackup(i) = 0
                     END DO
                  END IF
                  IF (found) THEN
                     print_key%ibackup(my_backup_level) = print_key%ibackup(my_backup_level) + 1
                     my_nbak = print_key%ibackup(my_backup_level)
                     ! Recent backup copies correspond to lower backup indexes
                     DO i = min(nbak, my_nbak), 2, -1
                        filename_bak_1 = trim(filename)//".bak-"//adjustl(cp_to_string(i))
                        filename_bak_2 = trim(filename)//".bak-"//adjustl(cp_to_string(i - 1))
                        IF (do_log) THEN
                           unit_nr = cp_logger_get_unit_nr(logger, local=my_local)
                           IF (unit_nr > 0) THEN
                              WRITE (unit_nr, *) "Moving file "//trim(filename_bak_2)// &
                                 " into file "//trim(filename_bak_1)//"."
                           END IF
                        END IF
                        INQUIRE (file=filename_bak_2, exist=found)
                        IF (.NOT. found) THEN
                           IF (do_log) THEN
                              unit_nr = cp_logger_get_unit_nr(logger, local=my_local)
                              IF (unit_nr > 0) THEN
                                 WRITE (unit_nr, *) "File "//trim(filename_bak_2)//" not existing.."
                              END IF
                           END IF
                        ELSE
                           ! Shared file: rotate on the source rank only; per-task
                           ! (my_local) files are per-rank, rotated by their owner.
                           IF (my_local .OR. logger%para_env%is_source()) THEN
                              CALL m_mov(trim(filename_bak_2), trim(filename_bak_1))
                           END IF
                        END IF
                     END DO
                     ! The last backup is always the one with index 1
                     filename_bak = trim(filename)//".bak-"//adjustl(cp_to_string(1))
                     IF (do_log) THEN
                        unit_nr = cp_logger_get_unit_nr(logger, local=my_local)
                        IF (unit_nr > 0) THEN
                           WRITE (unit_nr, *) "Moving file "//trim(filename)//" into file "//trim(filename_bak)//"."
                        END IF
                     END IF
                     IF (my_local .OR. logger%para_env%is_source()) THEN
                        CALL m_mov(trim(filename), trim(filename_bak))
                     END IF
                  ELSE
                     ! Zero the backup history for this new iteration level..
                     print_key%ibackup(my_backup_level) = 0
                  END IF
               END IF
            END IF
 
            IF (.NOT. my_mpi_io) THEN
               CALL open_file(file_name=filename, file_status=my_file_status, &
                              file_form=my_file_form, file_action=my_file_action, &
                              file_position=my_file_position, file_access=file_access, unit_number=res)
            ELSE
               IF (replace) CALL mp_file_delete(filename)
               CALL mp_unit%open(groupid=logger%para_env, &
                                 filepath=filename, amode_status=mpi_amode)
               IF (PRESENT(fout)) fout = filename
               res = mp_unit%get_handle()
            END IF
            IF (do_log) THEN
               unit_nr = cp_logger_get_unit_nr(logger, local=my_local)
               IF (unit_nr > 0) THEN
                  WRITE (unit_nr, *) "Writing "//trim(print_key%section%name)//" "// &
                     trim(cp_iter_string(logger%iter_info))//" to "// &
                     trim(filename)
               END IF
            END IF
         END IF
      ELSE
         res = -1
      END IF
   END FUNCTION cp_print_key_unit_nr
 
! **************************************************************************************************
!> \brief should be called after you finish working with a unit obtained with
!>      cp_print_key_unit_nr, so that the file that might have been opened
!>      can be closed.
!>
!>      the inputs should be exactly the same of the corresponding
!>      cp_print_key_unit_nr
!> \param unit_nr ...
!> \param logger ...
!> \param basis_section ...
!> \param print_key_path ...
!> \param local ...
!> \param ignore_should_output ...
!> \param on_file ...
!> \param mpi_io True if file was opened in parallel with MPI
!> \par History
!>      08.2002 created [fawzi]
!> \author Fawzi Mohamed
!> \note
!>      closes if the corresponding filename of the printkey is
!>      not __STD_OUT__
! **************************************************************************************************
   SUBROUTINE cp_print_key_finished_output(unit_nr, logger, basis_section, &
                                           print_key_path, local, ignore_should_output, on_file, &
                                           mpi_io)
      INTEGER, INTENT(INOUT)                             :: unit_nr
      TYPE(cp_logger_type), POINTER                      :: logger
      TYPE(section_vals_type), INTENT(IN)                :: basis_section
      CHARACTER(len=*), INTENT(IN), OPTIONAL             :: print_key_path
      LOGICAL, INTENT(IN), OPTIONAL                      :: local, ignore_should_output, on_file, &
                                                            mpi_io
 
      CHARACTER(len=default_string_length)               :: outpath
      LOGICAL                                            :: my_local, my_mpi_io, my_on_file, &
                                                            my_should_output
      TYPE(mp_file_type)                                 :: mp_unit
      TYPE(section_vals_type), POINTER                   :: print_key
 
      my_local = .false.
      my_on_file = .false.
      my_mpi_io = .false.
      NULLIFY (print_key)
      IF (PRESENT(local)) my_local = local
      IF (PRESENT(on_file)) my_on_file = on_file
      IF (PRESENT(mpi_io)) my_mpi_io = mpi_io
      cpassert(ASSOCIATED(logger))
      cpassert(basis_section%ref_count > 0)
      cpassert(logger%ref_count > 0)
      my_should_output = btest(cp_print_key_should_output(logger%iter_info, basis_section, &
                                                          print_key_path, used_print_key=print_key), cp_p_file)
      IF (PRESENT(ignore_should_output)) my_should_output = my_should_output .OR. ignore_should_output
      IF (my_should_output .AND. (my_local .OR. &
                                  logger%para_env%is_source() .OR. &
                                  my_mpi_io)) THEN
         CALL section_vals_val_get(print_key, "FILENAME", c_val=outpath)
         IF (my_on_file .OR. outpath /= '__STD_OUT__') THEN
            cpassert(unit_nr > 0)
            IF (.NOT. my_mpi_io) THEN
               CALL close_file(unit_nr, "KEEP")
            ELSE
               CALL mp_unit%set_handle(unit_nr)
               CALL mp_unit%close()
            END IF
            unit_nr = -1
         ELSE
            unit_nr = -1
         END IF
      END IF
      cpassert(unit_nr == -1)
      unit_nr = -1
   END SUBROUTINE cp_print_key_finished_output
 
! **************************************************************************************************
!> \brief Sets flag which determines whether or not to use MPI I/O for I/O routines that
!>        have been parallized with MPI
!> \param flag ...
!> \par History
!>      09.2018 created [Nico Holmberg]
! **************************************************************************************************
   SUBROUTINE cp_mpi_io_set(flag)
      LOGICAL, INTENT(IN)                                :: flag
 
      enable_mpi_io = flag
   END SUBROUTINE cp_mpi_io_set
 
! **************************************************************************************************
!> \brief Gets flag which determines whether or not to use MPI I/O for I/O routines that
!>        have been parallized with MPI
!> \return ...
!> \par History
!>      09.2018 created [Nico Holmberg]
! **************************************************************************************************
   FUNCTION cp_mpi_io_get() RESULT(flag)
      LOGICAL                                            :: flag
 
      flag = enable_mpi_io
   END FUNCTION cp_mpi_io_get
 
END MODULE cp_output_handling