README.md

Pipeliner - async python pipeline orchestrator

Pipeliner is a simple-to-use asynchronous pipeline orchestrator for python functions.

How to use:

1. register all steps using the @step decorator.
2. call the step you want the result from, providing any missing prerequisites as arguments.

How it works:

When a step is added, its arguments and return values are redirected to an internal value store holding Futures. Calling a step function creates a dependency tree of steps that provide prerequisites, and then queues them up to run whenever their own prerequisites become available. Steps without prerequisites will run first, then the steps that depend on those steps, and so on down to the root of the tree. If whatever resource a function provides is already present in the store when it is about to run, the function is not run and dependecy resolution continues as normal. This allows the user to skip parts of the tree by providing values.

The return values of the executed step are returned.

Example:

# example.py

from pipeliner import add_environment_resources, resource, step


@step(provides="base")
async def base_provider():
    print("base_provider called")
    return 23


@step(provides="result")
async def divide(base, divisor):
    print("divide called")
    return base // divisor


@step(provides="modulus")
async def mod(base, divisor):
    print("mod called")
    return base % divisor


@step(provides=("res_times_mod", "res_minus_mod"))
async def get_resmod(result, modulus):
    print("get_resmod called")
    return result * modulus, result - modulus


@step()
async def get_division(base, result, modulus):
    print("get_division called")
    return base, result, modulus


async def main():
    add_environment_resources(base=38)

    base, result, mod = await get_division(divisor=3)
    divisor = await resource("divisor")
    print(base, "divided by", divisor, "is", result, "with", mod, "left")

    times, minus = await get_resmod()  # All prerequisites already exist
    print("result x modulus is", times, "and result - modulus is", minus)


if __name__ == "__main__":
    import asyncio

    asyncio.run(main())

$ python example.py
divide called
mod called
get_division called  # since base is provided, base_provider will not run
38 divided by 3 is 12 with 2 left
get_resmod called
result x modulus is 24 and result - modulus is 10
$