How can I calculate a duration from start and end time

[kontango-bot]

here's my taskfile:

vars:
  start_time: "{{ now }}"

tasks:
  test:
    cmds:
      - sleep 5
      - task: end_timer
      - echo "Done."

  end_timer:
    cmds:
      - "echo Start time: {{ .start_time }}"
      - "echo End time: {{ now }}"
      - "echo Duration: {{ now.Sub mustToDate(.start_time) }}"

This is invalid syntax, and i've tried a few other things (e.g. without parens) that also seem to be invalid.

Part of the problem is that .start_time gets converted to a string, which is not suprising. I'm not sure how to convert it back into a date before passing it into now.Sub. Or, if there is a way to store now without converting it to a string, that would be ideal.

[kontango-bot]

It seems that vars are evaluated when they are called, so i don't think this approach will work either way.

[kontango-bot]

This is what I ended up with:

vars:
  start_time: { sh: date +%s }

tasks:
  test:
    cmds:
      - sleep 5
      - task: end_timer
      - echo "Done."

  end_timer:
    cmds:
      - "echo Duration: {{ .duration | duration }}"
    vars:
      duration: { sh: "echo $(( $(date +%s) - {{ .start_time }} ))" }

[matrixx567]

I've found another solution:

version: '3'

tasks:

  test:
    desc: "Test timing measurements of task" 
    cmds:
      - echo "⌚️ Test timing measurements of a task ⌚️"
      - echo ""

      - sleep 5

      - task: task_timer
        vars:
          start_time: '{{ now |unixEpoch }}'
    silent: true
  

  task_timer:
    desc: "Calculate timing of the calling task"
    # Call this task at the end of the caller task with following parameters:
    #   - task: task_timer
    #     vars:
    #       start_time: '{{ now | unixEpoch }}'
    summary: |
      This task is a helper task to calulate the duration in seconds
      for the caller task
    vars:
      end_time: '{{now | unixEpoch}}'
    requires:
      vars: [start_time]
    cmds:
      - 'echo ⏲️ -----------------------------------------------------------------------'
      # - 'echo ⏲️ StartTime: {{ .start_time }}   EndTime: {{ .end_time }}'
      - 'echo ⏲️ Duration: {{ sub .end_time .start_time | duration }}'
      - 'echo ⏲️ -----------------------------------------------------------------------'
    silent: true
    internal: true

[marco-m]

If I understand correctly the end goal, on Unix systems it is literally a 0 line:

Assume I would like to know how long utility foo takes. Instead of

tasks:
  test:
    cmds:
      - foo ...

I can do:

tasks:
  test:
    cmds:
      - time foo ...

Where time is a standard Unix utility: https://man7.org/linux/man-pages/man1/time.1.html. (Note that the majority of shells have time as a built-in).