tenacity/retry.py

# Copyright 2016–2021 Julien Danjou
# Copyright 2016 Joshua Harlow
# Copyright 2013-2014 Ray Holder
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

import abc
import re
import typing

if typing.TYPE_CHECKING:
    from tenacity import RetryCallState


class retry_base(abc.ABC):
    """Abstract base class for retry strategies."""

    @abc.abstractmethod
    def __call__(self, retry_state: "RetryCallState") -> bool:
        pass

    def __and__(self, other: "retry_base") -> "retry_all":
        return retry_all(self, other)

    def __or__(self, other: "retry_base") -> "retry_any":
        return retry_any(self, other)


class _retry_never(retry_base):
    """Retry strategy that never rejects any result."""

    def __call__(self, retry_state: "RetryCallState") -> bool:
        return False


retry_never = _retry_never()


class _retry_always(retry_base):
    """Retry strategy that always rejects any result."""

    def __call__(self, retry_state: "RetryCallState") -> bool:
        return True


retry_always = _retry_always()


class retry_if_exception(retry_base):
    """Retry strategy that retries if an exception verifies a predicate."""

    def __init__(self, predicate: typing.Callable[[BaseException], bool]) -> None:
        self.predicate = predicate

    def __call__(self, retry_state: "RetryCallState") -> bool:
        if retry_state.outcome.failed:
            return self.predicate(retry_state.outcome.exception())
        else:
            return False


class retry_if_exception_type(retry_if_exception):
    """Retries if an exception has been raised of one or more types."""

    def __init__(
        self,
        exception_types: typing.Union[
            typing.Type[BaseException],
            typing.Tuple[typing.Type[BaseException], ...],
        ] = Exception,
    ) -> None:
        self.exception_types = exception_types
        super().__init__(lambda e: isinstance(e, exception_types))


class retry_if_not_exception_type(retry_if_exception):
    """Retries except an exception has been raised of one or more types."""

    def __init__(
        self,
        exception_types: typing.Union[
            typing.Type[BaseException],
            typing.Tuple[typing.Type[BaseException], ...],
        ] = Exception,
    ) -> None:
        self.exception_types = exception_types
        super().__init__(lambda e: not isinstance(e, exception_types))


class retry_unless_exception_type(retry_if_exception):
    """Retries until an exception is raised of one or more types."""

    def __init__(
        self,
        exception_types: typing.Union[
            typing.Type[BaseException],
            typing.Tuple[typing.Type[BaseException], ...],
        ] = Exception,
    ) -> None:
        self.exception_types = exception_types
        super().__init__(lambda e: not isinstance(e, exception_types))

    def __call__(self, retry_state: "RetryCallState") -> bool:
        # always retry if no exception was raised
        if not retry_state.outcome.failed:
            return True
        return self.predicate(retry_state.outcome.exception())


class retry_if_result(retry_base):
    """Retries if the result verifies a predicate."""

    def __init__(self, predicate: typing.Callable[[typing.Any], bool]) -> None:
        self.predicate = predicate

    def __call__(self, retry_state: "RetryCallState") -> bool:
        if not retry_state.outcome.failed:
            return self.predicate(retry_state.outcome.result())
        else:
            return False


class retry_if_not_result(retry_base):
    """Retries if the result refutes a predicate."""

    def __init__(self, predicate: typing.Callable[[typing.Any], bool]) -> None:
        self.predicate = predicate

    def __call__(self, retry_state: "RetryCallState") -> bool:
        if not retry_state.outcome.failed:
            return not self.predicate(retry_state.outcome.result())
        else:
            return False


class retry_if_exception_message(retry_if_exception):
    """Retries if an exception message equals or matches."""

    def __init__(
        self,
        message: typing.Optional[str] = None,
        match: typing.Optional[str] = None,
    ) -> None:
        if message and match:
            raise TypeError(f"{self.__class__.__name__}() takes either 'message' or 'match', not both")

        # set predicate
        if message:

            def message_fnc(exception: BaseException) -> bool:
                return message == str(exception)

            predicate = message_fnc
        elif match:
            prog = re.compile(match)

            def match_fnc(exception: BaseException) -> bool:
                return bool(prog.match(str(exception)))

            predicate = match_fnc
        else:
            raise TypeError(f"{self.__class__.__name__}() missing 1 required argument 'message' or 'match'")

        super().__init__(predicate)


class retry_if_not_exception_message(retry_if_exception_message):
    """Retries until an exception message equals or matches."""

    def __init__(
        self,
        message: typing.Optional[str] = None,
        match: typing.Optional[str] = None,
    ) -> None:
        super().__init__(message, match)
        # invert predicate
        if_predicate = self.predicate
        self.predicate = lambda *args_, **kwargs_: not if_predicate(*args_, **kwargs_)

    def __call__(self, retry_state: "RetryCallState") -> bool:
        if not retry_state.outcome.failed:
            return True
        return self.predicate(retry_state.outcome.exception())


class retry_any(retry_base):
    """Retries if any of the retries condition is valid."""

    def __init__(self, *retries: retry_base) -> None:
        self.retries = retries

    def __call__(self, retry_state: "RetryCallState") -> bool:
        return any(r(retry_state) for r in self.retries)


class retry_all(retry_base):
    """Retries if all the retries condition are valid."""

    def __init__(self, *retries: retry_base) -> None:
        self.retries = retries

    def __call__(self, retry_state: "RetryCallState") -> bool:
        return all(r(retry_state) for r in self.retries)