Project Management and Async Functions

In my greatest display yet of over-engineering and procrastinating-with-tooling, I’ve started self-hosting OpenProject to track the tasks I want to carry out on my homelab (and their dependencies).

Annoyingly, I didn’t find out until after installation that this system lacks the main feature that made me want to use a Project Management Solution™ over a basic old Bunch Of Text Files - dependency visualization and easy identification of unblocked tasks.

Fortunately, the system has an API (of course), and some time later I’d whipped up this little “beauty” to print out all the unblocked tasks (i.e. all those I could start work on immediately):

#!/usr/bin/env python

import json
import os
import requests
import urllib3
urllib3.disable_warnings(urllib3.exceptions.InsecureRequestWarning)

PROJECT_ID=<id>
BASE_URL='http://url.to.my.openproject.installation'
API_KEY=os.environ['API_KEY']

def main():
  all_tasks = _req(f'api/v3/projects/{PROJECT_ID}/work_packages')['_embedded']['elements']
  unblocked_tasks = [
    {
      'id': elem['id'],
      'title': elem['subject'],
      'href': f'{BASE_URL}/work_packages/{elem["id"]}'
    } for elem in all_tasks
    if _task_is_unblocked(elem['id'])
  ]
  print(json.dumps(unblocked_tasks, indent=2))


def _task_is_unblocked(task_id: int) -> bool:
  relations_of_task = _req(f'api/v3/work_packages/{task_id}/relations')['_embedded']['elements']
  urls_to_blockers_of_task = [
    relation['_links']['from']['href']
    for relation in relations_of_task
    if relation['type'] == 'blocks'
    and relation['_links']['to']['href'].split('/')[4] == str(task_id)]
  return all([
    _req(url)['_embedded']['status']['isClosed']
    for url in urls_to_blockers_of_task])


def _req(path: str):
  return requests.get(f'{BASE_URL}/{path}', auth=('apikey', API_KEY), verify=False).json()

if __name__ == '__main__':
  main()

(Yes, I haven’t installed TLS on my cluster yet. The task’s right there in the screenshot, see!?)

This is, of course, inefficient as can possibly be[citation needed], as it doesn’t use any parallelization for the many network calls, nor any caching of often-referenced data. That’s fine for now, as N is going to be real small for quite some time.

Async functions as first-class language design

That actually gets me onto a different topic. For some years now I’ve enjoyed, shared, and referenced the What Color Is Your Function? article, which (spoilers - seriously, if you are a software engineer, go read it, it’s good!) points out the ways in which building-in async functions to a language make things really awkward when the rubber hits the road. For a long time I really resented this async annotation (which I first encountered in JavaScript, but I then found out it has spread to Python, too), as to me it seemed like unnecessary extra overhead - why should I have to annotate every function in my call-stack with async just because they called an asynchronous function at some point in the stack? Why, in the following snippet, does top_level() have to be async, when all it’s doing is a synchronous operation on an blocking function?

#!/usr/bin/env python
import asyncio

async def top_level():
  print(await mid_level() * 2)

async def mid_level():
  return await bottom_level() + 1

async def bottom_level():
  # Imagine that this called out to the network
  # or did some other actually-async operation
  return 1

if __name__ == '__main__':
  asyncio.run(top_level())

I recently read this article which made the interesting case that async should be thought of as a member of the Type System, surfacing information about the behaviour of the associated function:

Colored functions reveal important realities of a program. Colored functions are essentially a type-system manifestation of program effects, all of which can have dramatic consequences on performance (unorganized io calls can be a latency disaster), security (io can touch the filesystem or the network and open security gaps), global state consistency (async functions often mutate global state, and the filesystem isn’t the only example), and correctness/reliability (thrown exceptions are a program effect too, and a Result function is another kind of color). Colored functions don’t “poison” your program, they inform you of the reality that your program itself has been poisoned by these effects.

I…can see where they’re coming from, I guess? According to this viewpoint, mid_level should still be declared as async, even though it awaits the actually-asynchronous function, because…the “network-call-ingness” of bottom_level propagates up to mid_level? I hadn’t thought of it that way, but I can see that that’s true. My local definition of mid_level does nothing asynchronous, but asynchonicity is transitive.

Not gonna lie, though, I still find the experience of writing async-ified code really frustrating. I begin writing out my logic in terms of (normal) functions and their interactions, traversing down/through the logic tree from high-level concepts down to implementations of API calls - at which point I hit a network call, and then am forced to traverse back up the tree scattering async/awaits everywhere where I previously had normal function declarations and invocations. Maybe - and I’m half-joking, half-serious here - I should just start writing the program “as if” it was going to be asynchronous in the first place? I wonder what would change then.

• homelab
• programming-language-design
• SDLC