writer_field_manager.F90

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module writer_field_manager_mod
  use datadefn_mod, only : default_precision, string_length
  use configuration_parser_mod, only : io_configuration_type, data_values_type, io_configuration_field_type       
  use collections_mod, only : hashmap_type, map_type, iterator_type, mapentry_type, c_size, c_get_iterator, c_has_next, &
       c_next_mapentry, c_contains, c_get_string, c_get_generic, c_put_generic, c_is_empty, c_remove
  use conversions_mod, only : conv_to_string, conv_to_real
  use forthread_mod, only : forthread_mutex_init, forthread_mutex_lock, forthread_mutex_unlock, forthread_mutex_destroy, &
       forthread_rwlock_rdlock, forthread_rwlock_wrlock, forthread_rwlock_unlock, forthread_rwlock_init, forthread_rwlock_destroy
  use threadpool_mod, only : check_thread_status
  use data_utils_mod, only : get_scalar_integer_from_monc, get_scalar_real_from_monc, get_scalar_logical_from_monc, &
       is_field_present, get_array_double_from_monc, get_array_integer_from_monc, get_string_from_monc, get_map_from_monc, &
       unpack_scalar_integer_from_bytedata, unpack_scalar_dp_real_from_bytedata
  use io_server_client_mod, only : double_data_type, integer_data_type, string_data_type, scalar_field_type, map_field_type
  use logging_mod, only : log_warn, log_error, log_log
  use writer_federator_mod, only : is_field_used_by_writer_federator, provide_ordered_field_to_writer_federator, &
       is_field_split_on_q
  use writer_types_mod, only : prepare_to_serialise_data_values_type, serialise_data_values_type, unserialise_data_values_type
  use io_server_client_mod, only : pack_scalar_field
  use io_server_state_writer_mod, only : set_serialise_write_field_manager_state
  use io_server_state_reader_mod, only : reactivate_writer_field_manager_state
  implicit none

#ifndef TEST_MODE
  private
#endif

  type field_ordering_value_type
     character(len=STRING_LENGTH) :: field_name, field_namespace
     integer :: timestep, frequency, source
     type(data_values_type), allocatable :: field_values
     real(kind=DEFAULT_PRECISION) :: time
  end type field_ordering_value_type

  type field_ordering_type
     type(hashmap_type) :: timestep_to_value
     integer :: access_mutex, last_timestep_access, frequency
  end type field_ordering_type

  interface provide_field_to_writer_federator
     module procedure provide_field_to_writer_federator_rvalues_src, provide_field_to_writer_federator_rvalues_nosrc, &
          provide_field_to_writer_federator_src, provide_field_to_writer_federator_nosrc
  end interface provide_field_to_writer_federator

  integer, volatile :: field_lock
  type(hashmap_type), volatile :: field_orderings

  public initialise_writer_field_manager, finalise_writer_field_manager, provide_monc_data_to_writer_federator, &
       provide_field_to_writer_federator, is_write_field_manager_up_to_date
contains

  subroutine initialise_writer_field_manager(io_configuration, continuation_run)
    type(io_configuration_type), intent(inout) :: io_configuration
    logical, intent(in) :: continuation_run

    call check_thread_status(forthread_rwlock_init(field_lock, -1))
    call set_serialise_write_field_manager_state(serialise_field_manager_state, prepare_to_serialise_field_manager_state, &
         is_write_field_manager_up_to_date)
    if (continuation_run) then
      call reactivate_writer_field_manager_state(io_configuration, unserialise_field_manager_state)
    end if
  end subroutine initialise_writer_field_manager

  subroutine finalise_writer_field_manager()
    call check_thread_status(forthread_rwlock_destroy(field_lock))
  end subroutine finalise_writer_field_manager

  logical function is_write_field_manager_up_to_date(timestep)
    integer, intent(in) :: timestep

    type(iterator_type) :: iterator
    type(mapentry_type) :: mapentry
    class(*), pointer :: generic

    is_write_field_manager_up_to_date=.true.
    call check_thread_status(forthread_rwlock_rdlock(field_lock))
    iterator=c_get_iterator(field_orderings)
    do while (c_has_next(iterator))
      mapentry=c_next_mapentry(iterator)
      generic=>c_get_generic(mapentry)
      select type(generic)
        type is (field_ordering_type)
          if (generic%last_timestep_access .lt. timestep) then
            is_write_field_manager_up_to_date=.false.
            exit
          end if
      end select      
    end do    
    call check_thread_status(forthread_rwlock_unlock(field_lock))
  end function is_write_field_manager_up_to_date  

  subroutine provide_monc_data_to_writer_federator(io_configuration, source, data_id, data_dump)
    type(io_configuration_type), intent(inout) :: io_configuration
    integer, intent(in) :: source, data_id
    character, dimension(:), allocatable, intent(in) :: data_dump

    integer :: i, num_fields, timestep
    character(len=STRING_LENGTH) :: field_name, field_namespace
    real(kind=DEFAULT_PRECISION) :: time
    type(data_values_type) :: monc_value
    logical :: terminated_case

    if (is_field_present(io_configuration, source, data_id, "timestep") .and. &
         is_field_present(io_configuration, source, data_id, "time")) then
      timestep=get_scalar_integer_from_monc(io_configuration, source, data_id, data_dump, "timestep")
      time=get_scalar_real_from_monc(io_configuration, source, data_id, data_dump, "time")

      if (is_field_present(io_configuration, source, data_id, "terminated")) then
        terminated_case=get_scalar_logical_from_monc(io_configuration, source, data_id, data_dump, "terminated") .and. &
             io_configuration%data_definitions(data_id)%send_on_terminate
      else
        terminated_case=.false.
      end if

      num_fields=io_configuration%data_definitions(data_id)%number_of_data_fields

      do i=1, num_fields
        field_name=io_configuration%data_definitions(data_id)%fields(i)%name
        field_namespace=io_configuration%data_definitions(data_id)%fields(i)%namespace
        if (is_field_present(io_configuration, source, data_id, field_name) .and. &
             (is_field_used_by_writer_federator(field_name, field_namespace) .or. is_field_split_on_q(field_name))) then
          monc_value=get_value_from_monc_data(io_configuration, source, data_id, data_dump, field_name, field_namespace)
          call provide_field_to_writer_federator_src(io_configuration, field_name, field_namespace, monc_value, timestep, time, &
               io_configuration%data_definitions(data_id)%frequency, source, terminated_case)
          
          !deallocate(monc_value)
        end if
      end do
    else
      call log_log(log_warn, "Can not run pass MONC fields to writer federator without a time and timestep")
    end if
  end subroutine provide_monc_data_to_writer_federator

  function get_value_from_monc_data(io_configuration, source, data_id, data_dump, field_name, field_namespace)
    type(io_configuration_type), intent(inout) :: io_configuration
    integer, intent(in) :: source, data_id
    character, dimension(:), allocatable, intent(in) :: data_dump
    character(len=*), intent(in) :: field_name, field_namespace
    type(data_values_type) :: get_value_from_monc_data
    type(map_type) :: retrieved_map
    type(iterator_type) :: iterator
    type(mapentry_type) :: map_entry

    integer :: field_data_type, field_field_type, i
    integer, dimension(:), allocatable :: int_values

    call get_type_of_field(io_configuration%data_definitions(data_id)%fields, field_name, field_namespace, &
         field_field_type, field_data_type)
    if (field_data_type == 0) then
      call log_log(log_error, "No data type for field '"//trim(field_name)//"'")
    end if

    if (field_data_type == double_data_type) then
      get_value_from_monc_data%values=get_array_double_from_monc(io_configuration, source, data_id, data_dump, field_name)
      get_value_from_monc_data%data_type=double_data_type
    else if (field_data_type == integer_data_type) then
      get_value_from_monc_data%data_type=double_data_type
      int_values=get_array_integer_from_monc(io_configuration, source, data_id, data_dump, field_name)
      allocate(get_value_from_monc_data%values(size(int_values)))
      do i=1, size(int_values)
        get_value_from_monc_data%values(i)=conv_to_real(int_values(i))
      end do
      deallocate(int_values)
    else if (field_data_type == string_data_type) then
      get_value_from_monc_data%data_type=string_data_type
      if (field_field_type == scalar_field_type) then
        allocate(get_value_from_monc_data%string_values(1))
        get_value_from_monc_data%string_values(1)=get_string_from_monc(io_configuration, source, data_id, data_dump, field_name)
      else if (field_field_type == map_field_type) then        
        get_value_from_monc_data%map_values=get_map_from_monc(io_configuration, source, data_id, data_dump, field_name)        
      end if
    end if
  end function get_value_from_monc_data

  subroutine get_type_of_field(fields, field_name, field_namespace, field_type, data_type)
    type(io_configuration_field_type), dimension(:), intent(in) :: fields
    character(len=*), intent(in) :: field_name, field_namespace
    integer, intent(out) :: field_type, data_type

    integer :: i

    do i=1, size(fields)
      if (fields(i)%name .eq. field_name .and. fields(i)%namespace .eq. field_namespace) then
        data_type=fields(i)%data_type
        field_type=fields(i)%field_type
        return
      end if      
    end do
    data_type=0
    field_type=0
  end subroutine get_type_of_field

  subroutine provide_field_to_writer_federator_rvalues_src(io_configuration, field_name, field_namespace, &
       field_values, timestep, time, frequency, source)
    type(io_configuration_type), intent(inout) :: io_configuration
    character(len=*), intent(in) :: field_name, field_namespace
    integer, intent(in) :: timestep, frequency, source
    real(kind=DEFAULT_PRECISION), dimension(:), intent(in) :: field_values
    real(kind=DEFAULT_PRECISION), intent(in) :: time

    type(data_values_type) :: packaged_data
    
    allocate(packaged_data%values(size(field_values)))
    packaged_data%values=field_values
    packaged_data%data_type=double_data_type
    call provide_field_to_writer_federator_src(io_configuration, field_name, field_namespace, packaged_data, &
         timestep, time, frequency, source)
  end subroutine provide_field_to_writer_federator_rvalues_src

  subroutine provide_field_to_writer_federator_rvalues_nosrc(io_configuration, field_name, field_namespace, &
       field_values, timestep, time, frequency)
    type(io_configuration_type), intent(inout) :: io_configuration
    character(len=*), intent(in) :: field_name, field_namespace
    integer, intent(in) :: timestep, frequency
    real(kind=DEFAULT_PRECISION), dimension(:), intent(in) :: field_values
    real(kind=DEFAULT_PRECISION), intent(in) :: time

    call provide_field_to_writer_federator_rvalues_src(io_configuration, field_name, field_namespace, &
         field_values, timestep, time, frequency, -1)
  end subroutine provide_field_to_writer_federator_rvalues_nosrc

  subroutine provide_field_to_writer_federator_nosrc(io_configuration, field_name, field_namespace, &
       field_values, timestep, time, frequency)
    type(io_configuration_type), intent(inout) :: io_configuration
    character(len=*), intent(in) :: field_name, field_namespace
    integer, intent(in) :: timestep, frequency
    type(data_values_type), intent(inout) :: field_values
    real(kind=DEFAULT_PRECISION), intent(in) :: time

    call provide_field_to_writer_federator_src(io_configuration, field_name, field_namespace, &
         field_values, timestep, time, frequency, -1)
  end subroutine provide_field_to_writer_federator_nosrc
      
  subroutine provide_field_to_writer_federator_src(io_configuration, field_name, field_namespace, &
       field_values, timestep, time, frequency, source, terminated_case)
    type(io_configuration_type), intent(inout) :: io_configuration
    character(len=*), intent(in) :: field_name, field_namespace
    integer, intent(in) :: timestep, frequency, source
    type(data_values_type), intent(inout) :: field_values
    real(kind=DEFAULT_PRECISION), intent(in) :: time
    logical, intent(in), optional :: terminated_case

    type(field_ordering_type), pointer :: field_ordering
    class(*), pointer :: generic
    logical :: this_is_termination

    if (present(terminated_case)) then
      this_is_termination=terminated_case
    else
      this_is_termination=.false.
    end if

    field_ordering=>get_or_add_field_ordering(field_name, field_namespace, frequency, source)
    call check_thread_status(forthread_mutex_lock(field_ordering%access_mutex))
    if (timestep == field_ordering%last_timestep_access + frequency .or. this_is_termination) then
      if (.not. this_is_termination) field_ordering%last_timestep_access=timestep
      call provide_ordered_field_to_writer_federator(io_configuration, field_name, field_namespace, &
           field_values, timestep, time, source)
      if (allocated(field_values%values)) deallocate(field_values%values)      
    else
      generic=>generate_value_container(field_name, field_namespace, field_values, timestep, time, frequency, source)
      call c_put_generic(field_ordering%timestep_to_value, conv_to_string(timestep), generic, .false.)
    end if
    call process_queued_items(io_configuration, field_ordering)
    call check_thread_status(forthread_mutex_unlock(field_ordering%access_mutex))
  end subroutine provide_field_to_writer_federator_src

  subroutine process_queued_items(io_configuration, field_ordering)
    type(io_configuration_type), intent(inout) :: io_configuration
    type(field_ordering_type), intent(inout) :: field_ordering

    integer :: next_timestep
    type(field_ordering_value_type), pointer :: field_ordering_value_at_timestep

    do while (.not. c_is_empty(field_ordering%timestep_to_value))
      next_timestep=field_ordering%last_timestep_access + field_ordering%frequency
      if (c_contains(field_ordering%timestep_to_value, conv_to_string(next_timestep))) then
        field_ordering_value_at_timestep=>get_field_ordering_value_at_timestep(field_ordering%timestep_to_value, next_timestep)
        call c_remove(field_ordering%timestep_to_value, conv_to_string(next_timestep))
        field_ordering%last_timestep_access=next_timestep
        call provide_ordered_field_to_writer_federator(io_configuration, field_ordering_value_at_timestep%field_name, &
             field_ordering_value_at_timestep%field_namespace, field_ordering_value_at_timestep%field_values, &
             field_ordering_value_at_timestep%timestep, field_ordering_value_at_timestep%time, &
             field_ordering_value_at_timestep%source)
        if (allocated(field_ordering_value_at_timestep%field_values)) then
          if (allocated(field_ordering_value_at_timestep%field_values%values)) &
               deallocate(field_ordering_value_at_timestep%field_values%values)
          deallocate(field_ordering_value_at_timestep%field_values)
        end if
        deallocate(field_ordering_value_at_timestep)
      else
        exit
      end if
    end do
  end subroutine process_queued_items

  function get_field_ordering_value_at_timestep(collection, timestep)
    type(hashmap_type), intent(inout) :: collection
    integer, intent(in) :: timestep
    type(field_ordering_value_type), pointer :: get_field_ordering_value_at_timestep

    class(*), pointer :: generic

    generic=>c_get_generic(collection, conv_to_string(timestep))
    if (associated(generic)) then
      select type(generic)
        type is (field_ordering_value_type)
          get_field_ordering_value_at_timestep=>generic
      end select      
    else
      get_field_ordering_value_at_timestep=>null()
    end if    
  end function get_field_ordering_value_at_timestep  

  function generate_value_container(field_name, field_namespace, field_values, timestep, time, frequency, source)
    character(len=*), intent(in) :: field_name, field_namespace
    integer, intent(in) :: timestep, frequency, source
    type(data_values_type), intent(in) :: field_values
    real(kind=DEFAULT_PRECISION), intent(in) :: time
    type(field_ordering_value_type), pointer :: generate_value_container

    allocate(generate_value_container)
    generate_value_container%field_name=field_name
    generate_value_container%field_namespace=field_namespace
    generate_value_container%timestep=timestep
    generate_value_container%frequency=frequency
    generate_value_container%time=time
    generate_value_container%source=source
    allocate(generate_value_container%field_values, source=field_values)
  end function generate_value_container  

  function get_or_add_field_ordering(field_name, field_namespace, frequency, source)
    character(len=*), intent(in) :: field_name, field_namespace
    integer, intent(in) :: frequency, source
    type(field_ordering_type), pointer :: get_or_add_field_ordering

    class(*), pointer :: generic
    character(len=STRING_LENGTH) :: entry_key

    if (source .gt. -1) then
      entry_key=trim(field_name)//"#"//trim(field_namespace)//"#"//trim(conv_to_string(source))
    else
      entry_key=field_name
    end if

    get_or_add_field_ordering=>get_field_ordering(entry_key, .true.)
    if (.not. associated(get_or_add_field_ordering)) then
      call check_thread_status(forthread_rwlock_wrlock(field_lock))
      get_or_add_field_ordering=>get_field_ordering(entry_key, .false.)
      if (.not. associated(get_or_add_field_ordering)) then
        allocate(get_or_add_field_ordering)
        get_or_add_field_ordering%last_timestep_access=0
        get_or_add_field_ordering%frequency=frequency
        call check_thread_status(forthread_mutex_init(get_or_add_field_ordering%access_mutex, -1))
        generic=>get_or_add_field_ordering
        call c_put_generic(field_orderings, entry_key, generic, .false.)
      end if
      call check_thread_status(forthread_rwlock_unlock(field_lock))
    end if
  end function get_or_add_field_ordering
  
  function get_field_ordering(field_name, do_lock)
    character(len=*), intent(in) :: field_name
    logical, intent(in) :: do_lock
    type(field_ordering_type), pointer :: get_field_ordering

    class(*), pointer :: generic

    if (do_lock) call check_thread_status(forthread_rwlock_rdlock(field_lock))
    generic=>c_get_generic(field_orderings, field_name)
    if (do_lock) call check_thread_status(forthread_rwlock_unlock(field_lock))
    if (associated(generic)) then
      select type(generic)
        type is (field_ordering_type)
          get_field_ordering=>generic
      end select      
    else
      get_field_ordering=>null()
    end if
  end function get_field_ordering

  integer(kind=8) function prepare_to_serialise_field_manager_state()
    type(mapentry_type) :: map_entry
    type(iterator_type) :: iterator
    class(*), pointer :: generic

    call check_thread_status(forthread_rwlock_rdlock(field_lock))
    prepare_to_serialise_field_manager_state=kind(prepare_to_serialise_field_manager_state)

    iterator=c_get_iterator(field_orderings)
    do while (c_has_next(iterator))
      map_entry=c_next_mapentry(iterator)
      generic=>c_get_generic(map_entry)
      if (associated(generic)) then
        select type(generic)
        type is (field_ordering_type)
          prepare_to_serialise_field_manager_state=prepare_to_serialise_field_manager_state+&
               prepare_to_serialise_specific_field_ordering(generic)+&
               (kind(prepare_to_serialise_field_manager_state)*2)+len(trim(map_entry%key))
        end select
      end if
    end do
  end function prepare_to_serialise_field_manager_state

  subroutine serialise_field_manager_state(byte_data)
    character, dimension(:), allocatable, intent(inout) :: byte_data

    integer :: current_data_point, prev_pt
    type(mapentry_type) :: map_entry
    type(iterator_type) :: iterator
    class(*), pointer :: generic
 
    current_data_point=1
    current_data_point=pack_scalar_field(byte_data, current_data_point, c_size(field_orderings))

    iterator=c_get_iterator(field_orderings)
    do while (c_has_next(iterator))
      map_entry=c_next_mapentry(iterator)
      generic=>c_get_generic(map_entry)
      if (associated(generic)) then
        select type(generic)
        type is (field_ordering_type)
          current_data_point=pack_scalar_field(byte_data, current_data_point, len(trim(map_entry%key)))
          byte_data(current_data_point:current_data_point+len(trim(map_entry%key))-1) = transfer(trim(map_entry%key), &
               byte_data(current_data_point:current_data_point+len(trim(map_entry%key))-1))
          current_data_point=current_data_point+len(trim(map_entry%key))

          prev_pt=current_data_point
          current_data_point=current_data_point+kind(current_data_point)
          call serialise_specific_field_ordering(generic, byte_data, current_data_point)          
          prev_pt=pack_scalar_field(byte_data, prev_pt, (current_data_point-kind(current_data_point))-prev_pt)
        end select
      end if
    end do    
    
    call check_thread_status(forthread_rwlock_unlock(field_lock))
  end subroutine serialise_field_manager_state

  subroutine unserialise_field_manager_state(byte_data)
    character, dimension(:), intent(in) :: byte_data

    integer :: current_data_point, number_of_entries, i, byte_size, key_size
    character(len=STRING_LENGTH) :: value_key
    class(*), pointer :: generic

    current_data_point=1
    number_of_entries=unpack_scalar_integer_from_bytedata(byte_data, current_data_point)

    if (number_of_entries .gt. 0) then
      do i=1, number_of_entries
        key_size=unpack_scalar_integer_from_bytedata(byte_data, current_data_point)
        value_key=transfer(byte_data(current_data_point:current_data_point+key_size-1), value_key)
        value_key(key_size+1:)=" "
        current_data_point=current_data_point+key_size
        byte_size=unpack_scalar_integer_from_bytedata(byte_data, current_data_point)        
        generic=>unserialise_specific_field_ordering(byte_data(current_data_point:current_data_point+byte_size-1))
        call c_put_generic(field_orderings, value_key, generic, .false.)
        current_data_point=current_data_point+byte_size
      end do
    end if
  end subroutine unserialise_field_manager_state

  integer(kind=8) function prepare_to_serialise_specific_field_ordering(specific_field_ordering)
    type(field_ordering_type), intent(inout) :: specific_field_ordering

    type(mapentry_type) :: map_entry
    type(iterator_type) :: iterator
    class(*), pointer :: generic

    call check_thread_status(forthread_mutex_lock(specific_field_ordering%access_mutex))

    prepare_to_serialise_specific_field_ordering=kind(prepare_to_serialise_specific_field_ordering) * 3

    iterator=c_get_iterator(specific_field_ordering%timestep_to_value)
    do while (c_has_next(iterator))
      map_entry=c_next_mapentry(iterator)
      generic=>c_get_generic(map_entry)
      if (associated(generic)) then
        select type(generic)
        type is (field_ordering_value_type)
          prepare_to_serialise_specific_field_ordering=prepare_to_serialise_specific_field_ordering+&
               prepare_to_serialise_field_ordering_value(generic)+(kind(prepare_to_serialise_specific_field_ordering)*2)+&
               len(trim(map_entry%key))
        end select
      end if
    end do
  end function prepare_to_serialise_specific_field_ordering  

  subroutine serialise_specific_field_ordering(specific_field_ordering, byte_data, current_data_point)
    type(field_ordering_type), intent(inout) :: specific_field_ordering
    character, dimension(:), allocatable, intent(inout) :: byte_data
    integer, intent(inout) :: current_data_point

    integer :: prev_pt
    type(mapentry_type) :: map_entry
    type(iterator_type) :: iterator
    class(*), pointer :: generic
    
    current_data_point=pack_scalar_field(byte_data, current_data_point, specific_field_ordering%last_timestep_access)
    current_data_point=pack_scalar_field(byte_data, current_data_point, specific_field_ordering%frequency)
    current_data_point=pack_scalar_field(byte_data, current_data_point, c_size(specific_field_ordering%timestep_to_value))

    iterator=c_get_iterator(specific_field_ordering%timestep_to_value)
    do while (c_has_next(iterator))
      map_entry=c_next_mapentry(iterator)
      generic=>c_get_generic(map_entry)
      if (associated(generic)) then
        select type(generic)
        type is (field_ordering_value_type)
          current_data_point=pack_scalar_field(byte_data, current_data_point, len(trim(map_entry%key)))
          byte_data(current_data_point:current_data_point+len(trim(map_entry%key))-1) = transfer(trim(map_entry%key), &
               byte_data(current_data_point:current_data_point+len(trim(map_entry%key))-1))
          current_data_point=current_data_point+len(trim(map_entry%key))

          prev_pt=current_data_point
          current_data_point=current_data_point+kind(current_data_point)
          call serialise_field_ordering_value(generic, byte_data, current_data_point)          
          prev_pt=pack_scalar_field(byte_data, prev_pt, (current_data_point-kind(current_data_point))-prev_pt)
        end select
      end if
    end do
    
    call check_thread_status(forthread_mutex_unlock(specific_field_ordering%access_mutex))
  end subroutine serialise_specific_field_ordering
  
  function unserialise_specific_field_ordering(byte_data)
    character, dimension(:), intent(in) :: byte_data
    type(field_ordering_type), pointer :: unserialise_specific_field_ordering

    integer :: current_data_point, number_of_values, byte_size, i, key_size
    character(len=STRING_LENGTH) :: value_key
    class(*), pointer :: generic

    allocate(unserialise_specific_field_ordering)
    
    current_data_point=1
    unserialise_specific_field_ordering%last_timestep_access=unpack_scalar_integer_from_bytedata(byte_data, current_data_point)
    unserialise_specific_field_ordering%frequency=unpack_scalar_integer_from_bytedata(byte_data, current_data_point)
    number_of_values=unpack_scalar_integer_from_bytedata(byte_data, current_data_point)

    if (number_of_values .gt. 0) then
      do i=1, number_of_values
        key_size=unpack_scalar_integer_from_bytedata(byte_data, current_data_point)
        value_key=transfer(byte_data(current_data_point:current_data_point+key_size-1), value_key)
        value_key(key_size+1:)=" "
        current_data_point=current_data_point+key_size
        byte_size=unpack_scalar_integer_from_bytedata(byte_data, current_data_point)
        generic=>unserialise_field_ordering_value(byte_data(current_data_point:current_data_point+byte_size-1))
        call c_put_generic(unserialise_specific_field_ordering%timestep_to_value, value_key, generic, .false.)
        current_data_point=current_data_point+byte_size
      end do
    end if
    call check_thread_status(forthread_mutex_init(unserialise_specific_field_ordering%access_mutex, -1))
  end function unserialise_specific_field_ordering

  integer(kind=8) function prepare_to_serialise_field_ordering_value(specific_field_value)
    type(field_ordering_value_type), intent(inout) :: specific_field_value

    prepare_to_serialise_field_ordering_value=prepare_to_serialise_data_values_type(specific_field_value%field_values)
    prepare_to_serialise_field_ordering_value=prepare_to_serialise_field_ordering_value+&
         (kind(specific_field_value%timestep) * 6) + len(trim(specific_field_value%field_name)) + &
         len(trim(specific_field_value%field_namespace)) + kind(specific_field_value%time)
  end function prepare_to_serialise_field_ordering_value

  subroutine serialise_field_ordering_value(specific_field_value, byte_data, current_data_point)
    type(field_ordering_value_type), intent(inout) :: specific_field_value
    character, dimension(:), allocatable, intent(inout) :: byte_data
    integer, intent(inout) :: current_data_point

    integer :: prev_pt    
    
    current_data_point=pack_scalar_field(byte_data, current_data_point, specific_field_value%timestep)
    current_data_point=pack_scalar_field(byte_data, current_data_point, specific_field_value%frequency)
    current_data_point=pack_scalar_field(byte_data, current_data_point, specific_field_value%source)
    current_data_point=pack_scalar_field(byte_data, current_data_point, len(trim(specific_field_value%field_name)))
    byte_data(current_data_point:current_data_point+len(trim(specific_field_value%field_name))-1) = &
         transfer(trim(specific_field_value%field_name), byte_data(current_data_point:current_data_point+&
         len(trim(specific_field_value%field_name))-1))
    current_data_point=current_data_point+len(trim(specific_field_value%field_name))
    current_data_point=pack_scalar_field(byte_data, current_data_point, len(trim(specific_field_value%field_namespace)))
    byte_data(current_data_point:current_data_point+len(trim(specific_field_value%field_namespace))-1) = &
         transfer(trim(specific_field_value%field_namespace), byte_data(current_data_point:current_data_point+&
         len(trim(specific_field_value%field_namespace))-1))
    current_data_point=current_data_point+len(trim(specific_field_value%field_namespace))
    current_data_point=pack_scalar_field(byte_data, current_data_point, double_real_value=specific_field_value%time)

    prev_pt=current_data_point
    current_data_point=current_data_point+kind(current_data_point)
    call serialise_data_values_type(specific_field_value%field_values, byte_data, current_data_point)    
    prev_pt=pack_scalar_field(byte_data, prev_pt, (current_data_point-kind(current_data_point))-prev_pt)
  end subroutine serialise_field_ordering_value

  function unserialise_field_ordering_value(byte_data)
    character, dimension(:), intent(in) :: byte_data
    type(field_ordering_value_type), pointer :: unserialise_field_ordering_value

    integer :: current_data_point, byte_size, str_size

    allocate(unserialise_field_ordering_value)
    current_data_point=1
    unserialise_field_ordering_value%timestep=unpack_scalar_integer_from_bytedata(byte_data, current_data_point)
    unserialise_field_ordering_value%frequency=unpack_scalar_integer_from_bytedata(byte_data, current_data_point)
    unserialise_field_ordering_value%source=unpack_scalar_integer_from_bytedata(byte_data, current_data_point)
    str_size=unpack_scalar_integer_from_bytedata(byte_data, current_data_point)
    unserialise_field_ordering_value%field_name=transfer(byte_data(current_data_point:current_data_point+str_size-1), &
         unserialise_field_ordering_value%field_name)
    unserialise_field_ordering_value%field_name(str_size+1:)=" "
    current_data_point=current_data_point+str_size
    str_size=unpack_scalar_integer_from_bytedata(byte_data, current_data_point)
    unserialise_field_ordering_value%field_namespace=transfer(byte_data(current_data_point:current_data_point+str_size-1), &
         unserialise_field_ordering_value%field_namespace)
    unserialise_field_ordering_value%field_namespace(str_size+1:)=" "
    current_data_point=current_data_point+str_size
    unserialise_field_ordering_value%time=unpack_scalar_dp_real_from_bytedata(byte_data, current_data_point)
    byte_size=unpack_scalar_integer_from_bytedata(byte_data, current_data_point)        
    unserialise_field_ordering_value%field_values=unserialise_data_values_type(byte_data(current_data_point:&
         current_data_point+byte_size-1))
  end function unserialise_field_ordering_value
end module writer_field_manager_mod