import socket from time import sleep from typing import TYPE_CHECKING, Any, Callable, Iterable, Tuple, Type, TypeVar from redis.exceptions import ConnectionError, TimeoutError T = TypeVar("T") if TYPE_CHECKING: from redis.backoff import AbstractBackoff class Retry: """Retry a specific number of times after a failure""" def __init__( self, backoff: "AbstractBackoff", retries: int, supported_errors: Tuple[Type[Exception], ...] = ( ConnectionError, TimeoutError, socket.timeout, ), ): """ Initialize a `Retry` object with a `Backoff` object that retries a maximum of `retries` times. `retries` can be negative to retry forever. You can specify the types of supported errors which trigger a retry with the `supported_errors` parameter. """ self._backoff = backoff self._retries = retries self._supported_errors = supported_errors def update_supported_errors( self, specified_errors: Iterable[Type[Exception]] ) -> None: """ Updates the supported errors with the specified error types """ self._supported_errors = tuple( set(self._supported_errors + tuple(specified_errors)) ) def call_with_retry( self, do: Callable[[], T], fail: Callable[[Exception], Any], ) -> T: """ Execute an operation that might fail and returns its result, or raise the exception that was thrown depending on the `Backoff` object. `do`: the operation to call. Expects no argument. `fail`: the failure handler, expects the last error that was thrown """ self._backoff.reset() failures = 0 while True: try: return do() except self._supported_errors as error: failures += 1 fail(error) if self._retries >= 0 and failures > self._retries: raise error backoff = self._backoff.compute(failures) if backoff > 0: sleep(backoff)