import abc
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import socket
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from time import sleep
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from typing import (
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TYPE_CHECKING,
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Any,
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Callable,
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Generic,
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Iterable,
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Optional,
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Tuple,
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Type,
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TypeVar,
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)
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from redis.exceptions import ConnectionError, TimeoutError
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T = TypeVar("T")
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E = TypeVar("E", bound=Exception, covariant=True)
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if TYPE_CHECKING:
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from redis.backoff import AbstractBackoff
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|
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class AbstractRetry(Generic[E], abc.ABC):
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"""Retry a specific number of times after a failure"""
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_supported_errors: Tuple[Type[E], ...]
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def __init__(
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self,
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backoff: "AbstractBackoff",
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retries: int,
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supported_errors: Tuple[Type[E], ...],
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):
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"""
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Initialize a `Retry` object with a `Backoff` object
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that retries a maximum of `retries` times.
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`retries` can be negative to retry forever.
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You can specify the types of supported errors which trigger
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a retry with the `supported_errors` parameter.
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"""
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self._backoff = backoff
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self._retries = retries
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self._supported_errors = supported_errors
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@abc.abstractmethod
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def __eq__(self, other: Any) -> bool:
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return NotImplemented
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def __hash__(self) -> int:
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return hash((self._backoff, self._retries, frozenset(self._supported_errors)))
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def update_supported_errors(self, specified_errors: Iterable[Type[E]]) -> None:
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"""
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Updates the supported errors with the specified error types
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"""
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self._supported_errors = tuple(
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set(self._supported_errors + tuple(specified_errors))
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)
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def get_retries(self) -> int:
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"""
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Get the number of retries.
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"""
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return self._retries
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def update_retries(self, value: int) -> None:
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"""
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Set the number of retries.
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"""
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self._retries = value
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|
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class Retry(AbstractRetry[Exception]):
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__hash__ = AbstractRetry.__hash__
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def __init__(
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self,
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backoff: "AbstractBackoff",
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retries: int,
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supported_errors: Tuple[Type[Exception], ...] = (
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ConnectionError,
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TimeoutError,
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socket.timeout,
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),
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):
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super().__init__(backoff, retries, supported_errors)
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def __eq__(self, other: Any) -> bool:
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if not isinstance(other, Retry):
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return NotImplemented
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return (
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self._backoff == other._backoff
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and self._retries == other._retries
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and set(self._supported_errors) == set(other._supported_errors)
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)
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def call_with_retry(
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self,
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do: Callable[[], T],
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fail: Callable[[Exception], Any],
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is_retryable: Optional[Callable[[Exception], bool]] = None,
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) -> T:
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"""
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Execute an operation that might fail and returns its result, or
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raise the exception that was thrown depending on the `Backoff` object.
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`do`: the operation to call. Expects no argument.
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`fail`: the failure handler, expects the last error that was thrown
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"""
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self._backoff.reset()
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failures = 0
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while True:
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try:
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return do()
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except self._supported_errors as error:
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if is_retryable and not is_retryable(error):
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raise
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failures += 1
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fail(error)
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if self._retries >= 0 and failures > self._retries:
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raise error
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backoff = self._backoff.compute(failures)
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if backoff > 0:
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sleep(backoff)
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