example2-mocked-operations.py

import asyncio
from http import HTTPStatus

from aiohttp import web

REQUEST_COUNTER = 0


async def get_balance(request_id: int):
    await asyncio.sleep(0.2)
    print(f"{request_id}: get_balance done")


async def get_last_operation(request_id: int):
    await asyncio.sleep(0.1)
    print(f"{request_id}: get_last_operation done")


async def perform_debit(request_id: int):
    await asyncio.sleep(0.1)
    print(f"{request_id}: perform_debit done")


async def perform_credit(request_id: int):
    await asyncio.sleep(0.2)
    print(f"{request_id}: perform_credit done")


async def save_last_operation(request_id: int):
    await asyncio.sleep(0.1)
    print(f"{request_id}: save_last_operation done")


async def perform_transaction(request: web.Request) -> web.Response:
    global REQUEST_COUNTER
    request_id = REQUEST_COUNTER
    REQUEST_COUNTER += 1

    current_operation = await request.json()
    last_operation = await get_last_operation(request_id)

    if last_operation and last_operation == current_operation:
        return web.Response(status=HTTPStatus.BAD_REQUEST)

    await perform_debit(request_id)
    await perform_credit(request_id)
    await save_last_operation(request_id)

    return web.Response(status=HTTPStatus.OK)


app = web.Application()
app.add_routes([web.post('/', perform_transaction)])

web.run_app(app, port=8000)