redis.retry 源代码

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)