drive-flow 0.0.1a3

Build event-driven workflows with python async functions

drive-flow

Build event-driven workflows with python async functions

🌬️ Zero dependency. No trouble, no loss.

🍰 With intuitive decorators, write your async workflow like a piece of cake.

🔄 Support dynamic dispatch(goto, abort). Create a looping or if-else workflow with ease.

🔜 Fully asynchronous. Events are always triggered at the same time if they listen to the same group!

Install

Install from PyPi

pip install drive-flow

Install from source

# clone this repo first
cd drive-flow
pip install -e .

Quick Start

A hello world example:

import asyncio
from drive_flow import EventInput, default_drive


@default_drive.make_event
async def hello(event: EventInput, global_ctx):
    print("hello")

@default_drive.listen_group([hello])
async def world(event: EventInput, global_ctx):
    print("world")

asyncio.run(default_drive.invoke_event(hello))

In this example, The return of hello event will trigger world event.

To make an event function, there are few elements:

• Input Signature: must be (event: EventInput, global_ctx)
  • EventInput is the returns of the listening groups.
  • global_ctx is set by you when invoking events, it can be anything and default to None
• Make sure you decorate the function with @default_drive.make_event or @default_drive.listen_group([EVENT,...])

Then, run your workflow from any event:

await default_drive.invoke_event(EVENT, EVENT_INPUT, GLOBAL_CTX)

Check out examples for more user cases!

Features

Multi-Recv

drive_flow allow an event to be triggered only when a group of events are produced:

code snippet

@default_drive.make_event
async def start(event: EventInput, global_ctx):
    print("start")
    
@default_drive.listen_group([start])
async def hello(event: EventInput, global_ctx):
    return 1


@default_drive.listen_group([start])
async def world(event: EventInput, global_ctx):
    return 2


@default_drive.listen_group([hello, world])
async def adding(event: EventInput, global_ctx):
    results = event.results
    print("adding", hello, world)
    return results[hello.id] + results[world.id]


results = asyncio.run(default_drive.invoke_event(start))
assert results[adding.id] == 3

Parallel

drive_flow is perfect for workflows that have many network IO that can be awaited in parallel. If two events are listened to the same group of events, then they will be triggered at the same time:

code snippet

@default_drive.make_event
async def start(event: EventInput, global_ctx):
    print("start")

@default_drive.listen_group([start])
async def hello(event: EventInput, global_ctx):
    print(datetime.now(), "hello")
    await asyncio.sleep(0.2)
    print(datetime.now(), "hello done")


@default_drive.listen_group([start])
async def world(event: EventInput, global_ctx):
    print(datetime.now(), "world")
    await asyncio.sleep(0.2)
    print(datetime.now(), "world done")


asyncio.run(default_drive.invoke_event(start))

Dynamic

drive_flow is dynamic. You can use goto and abort to change the workflow at runtime:

code snippet for abort

from drive_flow.dynamic import abort_this

@default_drive.make_event
async def a(event: EventInput, global_ctx):
    return abort_this()

@default_drive.listen_group([a])
async def b(event: EventInput, global_ctx):
    assert False, "should not be called"
    
asyncio.run(default_drive.invoke_event(a))

code snippet for goto

from drive_flow.types import ReturnBehavior
from drive_flow.dynamic import goto_events, abort_this

call_a_count = 0
@default_drive.make_event
async def a(event: EventInput, global_ctx):
    global call_a_count
    if call_a_count == 0:
        assert event is None
    elif call_a_count == 1:
        assert event.behavior == ReturnBehavior.GOTO
        assert event.results == {b.id: 2}
        return abort_this()
    call_a_count += 1
    return 1

@default_drive.listen_group([a])
async def b(event: EventInput, global_ctx):
    return goto_events([a], 2)

@default_drive.listen_group([b])
async def c(event: EventInput, global_ctx):
    assert False, "should not be called"
    
asyncio.run(default_drive.invoke_event(a))