non-blocking-ipa-setup.py

from fastapi import FastAPI, BackgroundTasks
import requests
from requests.adapters import HTTPAdapter
from urllib3.util.retry import Retry
import time
import asyncio

app = FastAPI()

# Configure your parameters
URL = 'https://your.server.address/file'
TIMEOUT = 10  # seconds
RETRY_STRATEGY = Retry(
    total=5,  # Total number of retries
    backoff_factor=1,  # A backoff factor to apply between attempts
    status_forcelist=[429, 500, 502, 503, 504],  # Retry on these status codes
    method_whitelist=["HEAD", "GET", "OPTIONS"]  # Methods to retry
)

# Set up a session with the retry strategy
session = requests.Session()
adapter = HTTPAdapter(max_retries=RETRY_STRATEGY)
session.mount("https://", adapter)
session.mount("http://", adapter)

# Simulated Heartbeater
def heartbeater():
    while True:
        print("Heartbeat...")
        time.sleep(5)

# Simulated I/O Blocking Task for downloading a file
def download_file(url, timeout):
    try:
        # Stream the response to handle large files
        with session.get(url, timeout=timeout, stream=True) as response:
            response.raise_for_status()  # Raise an error for bad responses
            with open('downloaded_file', 'wb') as file:
                for chunk in response.iter_content(chunk_size=8192):
                    file.write(chunk)
            print("Download completed successfully.")
    except requests.exceptions.Timeout:
        print("The request timed out.")
    except requests.exceptions.RequestException as e:
        print(f"An error occurred: {e}")

@app.on_event("startup")
async def startup_event():
    # Starting Heartbeater in a separate thread
    import threading
    threading.Thread(target=heartbeater, daemon=True).start()

@app.post("/run-download-task")
async def run_download_task(background_tasks: BackgroundTasks):
    background_tasks.add_task(download_file, URL, TIMEOUT)
    return {"message": "Download task started"}

# To run the server, use: uvicorn this_script_name:app --reload