Refresh Proactive TTL Renewal in Python

import time
from datetime import datetime, timezone

class TTLRenewer:
    def __init__(self, ttl_seconds=10, renew_at=0.5):
        self.ttl = ttl_seconds
        self.last_renewed = time.time()
        self.renew_threshold = ttl_seconds * renew_at
        self.renewals = 0

    def check_and_renew(self):
        if time.time() - self.last_renewed > self.renew_threshold:
            self.renew()
        return self.remaining()

    def renew(self):
        self.last_renewed = time.time()
        self.renewals += 1
        print(f"[{datetime.now(timezone.utc).strftime('%H:%M:%S.%f')[:-3]}] TTL renewed | lifetime: {self.ttl}s")

    def remaining(self):
        return self.ttl - (time.time() - self.last_renewed)

if __name__ == "__main__":
    cache = TTLRenewer(ttl_seconds=5, renew_at=0.6)
    for i in range(8):
        time.sleep(1)
        remaining = cache.check_and_renew()
        print(f"t={i+1}s | remaining TTL: {remaining:.2f}s")
    print(f"Total renewals performed: {cache.renewals}")