Use datetime to control time #667

Whyborn · 2026-01-07T05:13:09Z

CABLE

Thank you for submitting a pull request to the CABLE Project.

Description

Testing using the fortran-datetime package, with some augmentations, to control time and triggering of events in CABLE.

📚 Documentation preview 📚: https://cable--667.org.readthedocs.build/en/667/

Whyborn · 2026-01-09T01:06:05Z

@SeanBryan51 The head of the branch now compiles in serial mode. I added a few functions to the fortran-datetime module here to check for new day/month/year.

SeanBryan51 · 2026-01-09T03:52:16Z

Thanks @Whyborn, this is exciting! I should be able to take a closer look at this on Monday

…' into 656-use-datetime-to-control-time

Whyborn · 2026-01-09T05:01:21Z

@SeanBryan51 I pulled the calendar checking into cable_offline_driver.F90, and now both MPI and serial build successfully. Doing a benchcab run now

Whyborn · 2026-01-09T06:20:28Z

Benchcab run shows bitwise compatibility

SeanBryan51

Thanks for this @Whyborn

I think it's worth trying out a CASA-CNP run, although we don't have a standard benchcab configuration for it. I've been doing my MPI-serial comparisons using this repo which is based off the payu crujra spatial configuration. It was pretty straight forward to adapt the base configuration to run a CASA (cold start) run, see this diff: SeanBryan51/crujra_accessN96_1h@main...casa-cnp-configuration

I'm happy to test this out with a CASA run using my scripts if you like?

SeanBryan51 · 2026-01-12T00:31:59Z

src/util/datetime_module.f90

@@ -0,0 +1,1496 @@
+module datetime_module


Always best to include a copy of the copyright and permission notice from the original repo (https://github.com/wavebitscientific/datetime-fortran/blob/main/LICENSE):

Suggested change

module datetime_module

! Copyright (c) 2013-2020 datetime-fortran contributors

!

! Permission is hereby granted, free of charge, to any person obtaining a copy

! of this software and associated documentation files (the "Software"), to deal

! in the Software without restriction, including without limitation the rights

! to use, copy, modify, merge, publish, distribute, sublicense, and/or sell

! copies of the Software, and to permit persons to whom the Software is

! furnished to do so, subject to the following conditions:

!

! The above copyright notice and this permission notice shall be included in all

! copies or substantial portions of the Software.

!

! THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

! IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

! FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE

! AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

! LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,

! OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE

! SOFTWARE.

module datetime_module

Yep for sure

SeanBryan51 · 2026-01-12T00:50:29Z

src/util/datetime_module.f90

+  pure elemental logical function isNewDay(d)
+    ! Determines whether the given `datetime` `d` is a the start of a month.
+    type(datetime), intent(in) :: d
+
+    isNewDay = (d%getHour() == 0 .and. d%getMinute() == 0 .and.&
+      d%getSecond() == 0 .and. d%getMillisecond() == 0)
+
+  end function isNewDay
+
+
+  pure elemental logical function isNewMonth(d)
+    ! Determines whether the given `datetime` `d` is the start of a month.
+    type(datetime), intent(in) :: d
+
+    isNewMonth = (d%getDay() == 1 .and. d%getHour() == 0 .and.&
+      d%getMinute() == 0 .and. d%getSecond() == 0 .and.&
+      d%getMillisecond() == 0)
+  end function isNewMonth
+
+
+  pure elemental logical function isNewYear(d)
+    ! Determines whether the given `datetime` `d` is the start of a year.
+    type(datetime), intent(in) :: d
+
+    isNewYear = (d%getMonth() == 1 .and. d%getDay() == 1 .and.&
+      d%getHour() == 0 .and. d%getMinute() == 0 .and.&
+      d%getSecond() == 0 .and. d%getMillisecond() == 0)
+  end function isNewYear


Are we sure that the datetime argument will be set such that the hour, minute, second and millisecond values are all zero? If the datetime argument is dependent on the time step then it might not line up exactly.

JULES uses this code which checks if going back a time step causes the current year to change which like seems like a clean way to do it

It would do, since they're integer values, you'll never get round-off error throwing off the counter, assuming that you check on initialisation that the time-step is a valid value that divides evenly into a day.

That JULES way is neater in some situations, but it does require two bits of information rather than 1, which could be more annoying passing it down the call stack. If I was to adopt a similar method I'd rather have routines like is_end_of_day, is_start_of_day, rather than advancing/retreating the timestep by 1 interval, so something like

curr_time = <some_datetime> dt = <some_timedelta> is_start_of_day(curr_time, dt) ! Would check the day of curr_time, and curr_time - dt is_end_of_day(curr_time, dt) ! Would check the day of curr_time, and curr_time + dt

The time step can be pretty large ~3 hours for some configurations, so advancing the datetime object by a time step might not hit hour 0?

I think it's a requirement already (implicitly if not explicitly) that timesteps must fit evenly into a day? Otherwise I think the current methods of checking would fail/be inconsistent

You might be right, I'm not too familiar with how the time step is set.

Can you confirm what the valid time steps are? I'm also wondering about coupled model and what they use for the time step?

Whyborn · 2026-01-12T02:47:05Z

I'll give a go with the CASA-CNP configuration- I should be able to just clone the branch from your repo right?

Whyborn · 2026-01-12T05:15:55Z

Unfortunately getting entirely unhelpful MPI errors when running the branch with MPI. Might have to run it through a debugger

Whyborn added 18 commits December 12, 2025 11:39

Remove unused file

7d53910

Start substitution of datetime with initialisation

b042689

Add datetime module

0a75dc1

Minor changes to make it compile

fe75799

Add end of period checks and apply them to is_casa_time

4500c9e

More instances of specific timings being updated

8237986

Take dt out of cable_input

fb2f462

Fix some typos

2a06a3d

try removing seemingly unused nday and ndays

6c73c32

Temporarily reintroduce old IS_CASA_TIME function

dd14d05

Change CASAONLY_LUC version of IS_CASA_TIME

7677535

Remove doubly defined variable and re-add required variable

6915dd3

Remove unused ktau variable from biogeochem

2d6443b

Remove ktau from biogeochem body

a10efb5

Reorder function args to be more logical

4e43da6

Fix data type of ktauday

ee020af

Re-add accidentally removed line

8470c00

Fix is_casa_time args and move dt definition

6ef1d3f

Whyborn added 2 commits January 9, 2026 12:06

missing s in keyword arg

0d8a67d

Try to get the MPI building as well, and fix ts_start not being updated

4a4c19a

Whyborn added 8 commits January 9, 2026 14:52

Merge remote-tracking branch 'origin/656-use-datetime-to-control-time…

d142e36

…' into 656-use-datetime-to-control-time

add missing module

946a0cc

Move calender selection to the offline driver

4ad5260

Correct setcalendar name

6e2cd1e

Import leaps to the main driver

79e5cff

Fix type

3c321a1

Fix typo

c1cd117

Final couple of fixes

af4d847

SeanBryan51 reviewed Jan 12, 2026

View reviewed changes

Update ts_start at end of timestep

94487d0

-module datetime_module
+! Copyright (c) 2013-2020 datetime-fortran contributors
+!
+! Permission is hereby granted, free of charge, to any person obtaining a copy
+! of this software and associated documentation files (the "Software"), to deal
+! in the Software without restriction, including without limitation the rights
+! to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+! copies of the Software, and to permit persons to whom the Software is
+! furnished to do so, subject to the following conditions:
+!
+! The above copyright notice and this permission notice shall be included in all
+! copies or substantial portions of the Software.
+!
+! THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+! IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+! FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+! AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+! LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+! OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+! SOFTWARE.
+module datetime_module

Use datetime to control time #667

Are you sure you want to change the base?

Use datetime to control time #667

Uh oh!

Conversation

Whyborn commented Jan 7, 2026 • edited by github-actions bot Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

CABLE

Description

Uh oh!

Whyborn commented Jan 9, 2026

Uh oh!

SeanBryan51 commented Jan 9, 2026

Uh oh!

Whyborn commented Jan 9, 2026

Uh oh!

Whyborn commented Jan 9, 2026

Uh oh!

SeanBryan51 left a comment

Choose a reason for hiding this comment

Uh oh!

SeanBryan51 Jan 12, 2026

Choose a reason for hiding this comment

Uh oh!

Whyborn Jan 12, 2026

Choose a reason for hiding this comment

Uh oh!

SeanBryan51 Jan 12, 2026

Choose a reason for hiding this comment

Uh oh!

Whyborn Jan 12, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

Uh oh!

SeanBryan51 Jan 12, 2026

Choose a reason for hiding this comment

Uh oh!

Whyborn Jan 12, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

Uh oh!

SeanBryan51 Jan 12, 2026

Choose a reason for hiding this comment

Uh oh!

Whyborn commented Jan 12, 2026

Uh oh!

Whyborn commented Jan 12, 2026

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

3 participants

Whyborn commented Jan 7, 2026 •

edited by github-actions bot

Loading

Whyborn Jan 12, 2026 •

edited

Loading

Whyborn Jan 12, 2026 •

edited

Loading