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from asyncio import sleep
from typing import TYPE_CHECKING, Any, Awaitable, Callable, Tuple, Type, TypeVar
from redis.exceptions import ConnectionError, RedisError, TimeoutError
if TYPE_CHECKING:
from redis.backoff import AbstractBackoff
T = TypeVar("T")
class Retry:
"""Retry a specific number of times after a failure"""
__slots__ = "_backoff", "_retries", "_supported_errors"
def __init__(
self,
backoff: "AbstractBackoff",
retries: int,
supported_errors: Tuple[Type[RedisError], ...] = (
ConnectionError,
TimeoutError,
),
):
"""
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
async def call_with_retry(
self, do: Callable[[], Awaitable[T]], fail: Callable[[RedisError], 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 await do()
except self._supported_errors as error:
failures += 1
await fail(error)
if self._retries >= 0 and failures > self._retries:
raise error
backoff = self._backoff.compute(failures)
if backoff > 0:
await sleep(backoff)
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