Code Demo · Python · Retry and Backoff

import time
from typing import Callable, Optional, TypeVar

T = TypeVar("T")

def retry(operation: Callable[[], T], attempts: int = 4, base_delay: float = 0.05) -> T:
    last_error: Optional[RuntimeError] = None
    for attempt in range(attempts):
        try:
            return operation()
        except RuntimeError as error:
            last_error = error
            if attempt == attempts - 1:
                raise
            time.sleep(base_delay * (2 ** attempt))
    if last_error is not None:
        raise last_error
    raise RuntimeError("retry exhausted")

calls = 0
def flaky_operation() -> str:
    global calls
    calls += 1
    if calls < 3:
        raise RuntimeError("temporary failure")
    return "recovered"

print(retry(flaky_operation), "after", calls, "attempts")