Massive Computation

app.py

from celery import Celery
from flask import Flask
import time

# 1. A function to create Celery object.
def make_celery(app):
    celery = Celery(
        app.import_name,
        backend=app.config["CELERY_RESULT_BACKEND"],
        broker=app.config["CELERY_BROKER_URL"],
    )
    celery.conf.update(app.config)

    class ContextTask(celery.Task):
        def __call__(self, *args, **kwargs):
            with app.app_context():
                return self.run(*args, **kwargs)

    celery.Task = ContextTask
    return celery


# 2. Create a Flask app
app = Flask(__name__)
app.config.update(
    CELERY_BROKER_URL="redis://localhost:6379",
    CELERY_RESULT_BACKEND="redis://localhost:6379",
)

# 3. Connect Flask with Celery
celery = make_celery(app)

# 4. Now, we can create Celery tasks by annotating @celery.task
@celery.task()
def massive_computation(name):
    time.sleep(5)
    return f"Hello {name}"

app2.py

# Create a redis database instance
# ------------------------------------------------------------------
import redis

r = redis.Redis(host="localhost", port=6379, db=0)
# -------------------------------------------------------------------------

r.set("last_calculated_value", 0)  # Set it's initial value to 0.

# Asynchronous execution
# -------------------------------------------------------------------------
def fib(n):
    """This function will calculate the Fibonacci number"""
    return n if n < 2 else fib(n - 1) + fib(n - 2)


@celery.task()
def massive_computation(num: int):
    r.set("last_calculated_value", fib(num))
# -------------------------------------------------------------------------

# Web api endpoints
# -------------------------------------------------------------------------
@app.route("/set/<num>")
def set_fib(num: int = 0):
    massive_computation.delay(int(num))
    return "New Fibonacci number will be assigned soon."


@app.route("/current")
def get_current():
    last_calculated_value = r.get("last_calculated_value")
    return f"Current fibonacci number is {last_calculated_value}\n"
# -------------------------------------------------------------------------