add flush method

Author: scivision

Examples.md

@@ -42,6 +42,14 @@ If `%finalize()` or hdf5_close is not called, data loss can result.
 call h5f%finalize()
 ```
 
+At any time during the program, the `%flush()` method can be called to request the operating system to write a file to disk.
+This could be useful during a long-running program (say, an HPC simulation) to help ensure data isn't lost of an HDF5 file is open for a long time.
+The flush request is on a per-file basis, so if multiple files are open, flush each file to protect against data loss in this case.
+
+```fortran
+call h5f%flush()
+```
+
 ## create temporary "scratch" file
 
 Analogous to regular Fortran `open(status='scratch')`, the file created will attempt to be deleted.

src/interface.f90

@@ -4,14 +4,14 @@ module h5fortran
 use, intrinsic :: iso_fortran_env, only : real32, real64, int64, int32, stderr=>error_unit
 use hdf5, only : HID_T, SIZE_T, HSIZE_T, H5F_ACC_RDONLY_F, H5F_ACC_RDWR_F, H5F_ACC_TRUNC_F, &
   H5S_ALL_F, H5S_SELECT_SET_F, &
-  H5T_NATIVE_DOUBLE, H5T_NATIVE_REAL, H5T_NATIVE_INTEGER, H5T_NATIVE_CHARACTER, &
+  H5T_NATIVE_DOUBLE, H5T_NATIVE_REAL, H5T_NATIVE_INTEGER, H5T_NATIVE_CHARACTER, H5F_SCOPE_GLOBAL_F, &
   h5open_f, h5close_f, &
   h5dopen_f, h5dclose_f, h5dget_space_f, &
   h5gcreate_f, h5gclose_f, &
   h5fopen_f, h5fcreate_f, h5fclose_f, h5fis_hdf5_f, &
   h5lexists_f, &
   h5sclose_f, h5sselect_hyperslab_f, h5screate_simple_f, &
-  h5get_libversion_f, h5eset_auto_f
+  h5get_libversion_f, h5eset_auto_f, h5fflush_f
 use h5lt, only : h5ltget_dataset_ndims_f, h5ltget_dataset_info_f
 
 use pathlib, only : unlink, get_tempdir, is_absolute_path
@@ -47,7 +47,7 @@ module h5fortran
 !> initialize HDF5 file
 procedure, public :: initialize => hdf_initialize, finalize => hdf_finalize, &
   write_group, writeattr, &
-  open => hdf_open_group, close => hdf_close_group, &
+  open => hdf_open_group, close => hdf_close_group, flush => hdf_flush, &
   rank => hdf_get_ndims, ndims => hdf_get_ndims, &
   shape => hdf_get_shape, layout => hdf_get_layout, chunks => hdf_get_chunk, &
   exist => hdf_check_exist, exists => hdf_check_exist, &
@@ -522,6 +522,22 @@ subroutine hdf_finalize(self, ierr, close_hdf5_interface)
 end subroutine hdf_finalize
 
 
+subroutine hdf_flush(self, ierr)
+
+class(hdf5_file), intent(in) :: self
+integer, intent(out), optional :: ierr
+integer :: ier
+
+call h5fflush_f(self%lid, H5F_SCOPE_GLOBAL_F, ier)
+if (present(ierr)) ierr = ier
+if (check(ier, 'ERROR: HDF5 flush ' // self%filename)) then
+  if (present(ierr)) return
+  error stop
+endif
+
+end subroutine hdf_flush
+
+
 subroutine hdf5_close(ierr)
 !! this subroutine will close ALL existing file handles
 !! only call it at end of your program

src/tests/test_exist.f90

@@ -103,6 +103,7 @@ subroutine test_multifiles()
 if (h%is_open) error stop 'is_open not isolated at constructor'
 call h%initialize(filename='C.h5', status='scratch')
 
+call f%flush()
 
 call f%finalize(ierr)
 if (ierr/=0) error stop 'close a.h5'