# -*- coding: utf-8 -*-
# Copyright 2016-2018 Julien Danjou
# Copyright 2017 Elisey Zanko
# Copyright 2016 Étienne Bersac
# 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.
try:
import asyncio
except ImportError:
asyncio = None
try:
import tornado
except ImportError:
tornado = None
import sys
import threading
from concurrent import futures
import six
from tenacity import _utils
from tenacity import compat as _compat
# Import all built-in retry strategies for easier usage.
from .retry import retry_all # noqa
from .retry import retry_always # noqa
from .retry import retry_any # noqa
from .retry import retry_if_exception # noqa
from .retry import retry_if_exception_type # noqa
from .retry import retry_if_not_result # noqa
from .retry import retry_if_result # noqa
from .retry import retry_never # noqa
from .retry import retry_unless_exception_type # noqa
from .retry import retry_if_exception_message # noqa
from .retry import retry_if_not_exception_message # noqa
# Import all nap strategies for easier usage.
from .nap import sleep # noqa
from .nap import sleep_using_event # noqa
# Import all built-in stop strategies for easier usage.
from .stop import stop_after_attempt # noqa
from .stop import stop_after_delay # noqa
from .stop import stop_all # noqa
from .stop import stop_any # noqa
from .stop import stop_never # noqa
from .stop import stop_when_event_set # noqa
# Import all built-in wait strategies for easier usage.
from .wait import wait_chain # noqa
from .wait import wait_combine # noqa
from .wait import wait_exponential # noqa
from .wait import wait_fixed # noqa
from .wait import wait_incrementing # noqa
from .wait import wait_none # noqa
from .wait import wait_random # noqa
from .wait import wait_random_exponential # noqa
from .wait import wait_random_exponential as wait_full_jitter # noqa
# Import all built-in before strategies for easier usage.
from .before import before_log # noqa
from .before import before_nothing # noqa
# Import all built-in after strategies for easier usage.
from .after import after_log # noqa
from .after import after_nothing # noqa
# Import all built-in after strategies for easier usage.
from .before_sleep import before_sleep_log # noqa
from .before_sleep import before_sleep_nothing # noqa
def retry(*dargs, **dkw):
"""Wrap a function with a new `Retrying` object.
:param dargs: positional arguments passed to Retrying object
:param dkw: keyword arguments passed to the Retrying object
"""
# support both @retry and @retry() as valid syntax
if len(dargs) == 1 and callable(dargs[0]):
return retry()(dargs[0])
else:
def wrap(f):
if asyncio and asyncio.iscoroutinefunction(f):
r = AsyncRetrying(*dargs, **dkw)
elif tornado and hasattr(tornado.gen, 'is_coroutine_function') \
and tornado.gen.is_coroutine_function(f):
r = TornadoRetrying(*dargs, **dkw)
else:
r = Retrying(*dargs, **dkw)
return r.wraps(f)
return wrap
class TryAgain(Exception):
"""Always retry the executed function when raised."""
NO_RESULT = object()
class DoAttempt(object):
pass
class DoSleep(float):
pass
class BaseAction(object):
"""Base class for representing actions to take by retry object.
Concrete implementations must define:
- __init__: to initialize all necessary fields
- REPR_ATTRS: class variable specifying attributes to include in repr(self)
- NAME: for identification in retry object methods and callbacks
"""
REPR_FIELDS = ()
NAME = None
def __repr__(self):
state_str = ', '.join('%s=%r' % (field, getattr(self, field))
for field in self.REPR_FIELDS)
return '%s(%s)' % (type(self).__name__, state_str)
def __str__(self):
return repr(self)
class RetryAction(BaseAction):
REPR_FIELDS = ('sleep',)
NAME = 'retry'
def __init__(self, sleep):
self.sleep = float(sleep)
_unset = object()
class RetryError(Exception):
"""Encapsulates the last attempt instance right before giving up."""
def __init__(self, last_attempt):
self.last_attempt = last_attempt
super(RetryError, self).__init__(last_attempt)
def reraise(self):
if self.last_attempt.failed:
raise self.last_attempt.result()
raise self
def __str__(self):
return "{0}[{1}]".format(self.__class__.__name__, self.last_attempt)
class BaseRetrying(object):
def __init__(self,
sleep=sleep,
stop=stop_never, wait=wait_none(),
retry=retry_if_exception_type(),
before=before_nothing,
after=after_nothing,
before_sleep=None,
reraise=False,
retry_error_cls=RetryError,
retry_error_callback=None):
self.sleep = sleep
self._stop = stop
self._wait = wait
self._retry = retry
self._before = before
self._after = after
self._before_sleep = before_sleep
self.reraise = reraise
self._local = threading.local()
self.retry_error_cls = retry_error_cls
self._retry_error_callback = retry_error_callback
# This attribute was moved to RetryCallState and is deprecated on
# Retrying objects but kept for backward compatibility.
self.fn = None
@_utils.cached_property
def stop(self):
return _compat.stop_func_accept_retry_state(self._stop)
@_utils.cached_property
def wait(self):
return _compat.wait_func_accept_retry_state(self._wait)
@_utils.cached_property
def retry(self):
return _compat.retry_func_accept_retry_state(self._retry)
@_utils.cached_property
def before(self):
return _compat.before_func_accept_retry_state(self._before)
@_utils.cached_property
def after(self):
return _compat.after_func_accept_retry_state(self._after)
@_utils.cached_property
def before_sleep(self):
return _compat.before_sleep_func_accept_retry_state(self._before_sleep)
@_utils.cached_property
def retry_error_callback(self):
return _compat.retry_error_callback_accept_retry_state(
self._retry_error_callback)
def copy(self, sleep=_unset, stop=_unset, wait=_unset,
retry=_unset, before=_unset, after=_unset, before_sleep=_unset,
reraise=_unset):
"""Copy this object with some parameters changed if needed."""
if before_sleep is _unset:
before_sleep = self.before_sleep
return self.__class__(
sleep=self.sleep if sleep is _unset else sleep,
stop=self.stop if stop is _unset else stop,
wait=self.wait if wait is _unset else wait,
retry=self.retry if retry is _unset else retry,
before=self.before if before is _unset else before,
after=self.after if after is _unset else after,
before_sleep=before_sleep,
reraise=self.reraise if after is _unset else reraise,
)
def __repr__(self):
attrs = dict(
_utils.visible_attrs(self, attrs={'me': id(self)}),
__class__=self.__class__.__name__,
)
return ("<%(__class__)s object at 0x%(me)x (stop=%(stop)s, "
"wait=%(wait)s, sleep=%(sleep)s, retry=%(retry)s, "
"before=%(before)s, after=%(after)s)>") % (attrs)
@property
def statistics(self):
"""Return a dictionary of runtime statistics.
This dictionary will be empty when the controller has never been
ran. When it is running or has ran previously it should have (but
may not) have useful and/or informational keys and values when
running is underway and/or completed.
.. warning:: The keys in this dictionary **should** be some what
stable (not changing), but there existence **may**
change between major releases as new statistics are
gathered or removed so before accessing keys ensure that
they actually exist and handle when they do not.
.. note:: The values in this dictionary are local to the thread
running call (so if multiple threads share the same retrying
object - either directly or indirectly) they will each have
there own view of statistics they have collected (in the
future we may provide a way to aggregate the various
statistics from each thread).
"""
try:
return self._local.statistics
except AttributeError:
self._local.statistics = {}
return self._local.statistics
def wraps(self, f):
"""Wrap a function for retrying.
:param f: A function to wraps for retrying.
"""
@_utils.wraps(f)
def wrapped_f(*args, **kw):
return self.call(f, *args, **kw)
def retry_with(*args, **kwargs):
return self.copy(*args, **kwargs).wraps(f)
wrapped_f.retry = self
wrapped_f.retry_with = retry_with
return wrapped_f
def begin(self, fn):
self.statistics.clear()
self.statistics['start_time'] = _utils.now()
self.statistics['attempt_number'] = 1
self.statistics['idle_for'] = 0
self.fn = fn
def iter(self, retry_state): # noqa
fut = retry_state.outcome
if fut is None:
if self.before is not None:
self.before(retry_state)
return DoAttempt()
is_explicit_retry = retry_state.outcome.failed \
and isinstance(retry_state.outcome.exception(), TryAgain)
if not (is_explicit_retry or self.retry(retry_state=retry_state)):
return fut.result()
if self.after is not None:
self.after(retry_state=retry_state)
self.statistics['delay_since_first_attempt'] = \
retry_state.seconds_since_start
if self.stop(retry_state=retry_state):
if self.retry_error_callback:
return self.retry_error_callback(retry_state=retry_state)
retry_exc = self.retry_error_cls(fut)
if self.reraise:
raise retry_exc.reraise()
six.raise_from(retry_exc, fut.exception())
if self.wait:
sleep = self.wait(retry_state=retry_state)
else:
sleep = 0.0
retry_state.next_action = RetryAction(sleep)
retry_state.idle_for += sleep
self.statistics['idle_for'] += sleep
self.statistics['attempt_number'] += 1
if self.before_sleep is not None:
self.before_sleep(retry_state=retry_state)
return DoSleep(sleep)
class Retrying(BaseRetrying):
"""Retrying controller."""
def call(self, fn, *args, **kwargs):
self.begin(fn)
retry_state = RetryCallState(
retry_object=self, fn=fn, args=args, kwargs=kwargs)
while True:
do = self.iter(retry_state=retry_state)
if isinstance(do, DoAttempt):
try:
result = fn(*args, **kwargs)
except BaseException:
retry_state.set_exception(sys.exc_info())
else:
retry_state.set_result(result)
elif isinstance(do, DoSleep):
retry_state.prepare_for_next_attempt()
self.sleep(do)
else:
return do
__call__ = call
class Future(futures.Future):
"""Encapsulates a (future or past) attempted call to a target function."""
def __init__(self, attempt_number):
super(Future, self).__init__()
self.attempt_number = attempt_number
@property
def failed(self):
"""Return whether a exception is being held in this future."""
return self.exception() is not None
@classmethod
def construct(cls, attempt_number, value, has_exception):
"""Construct a new Future object."""
fut = cls(attempt_number)
if has_exception:
fut.set_exception(value)
else:
fut.set_result(value)
return fut
class RetryCallState(object):
"""State related to a single call wrapped with Retrying."""
def __init__(self, retry_object, fn, args, kwargs):
#: Retry call start timestamp
self.start_time = _utils.now()
#: Retry manager object
self.retry_object = retry_object
#: Function wrapped by this retry call
self.fn = fn
#: Arguments of the function wrapped by this retry call
self.args = args
#: Keyword arguments of the function wrapped by this retry call
self.kwargs = kwargs
#: The number of the current attempt
self.attempt_number = 1
#: Last outcome (result or exception) produced by the function
self.outcome = None
#: Timestamp of the last outcome
self.outcome_timestamp = None
#: Time spent sleeping in retries
self.idle_for = 0
#: Next action as decided by the retry manager
self.next_action = None
@property
def seconds_since_start(self):
if self.outcome_timestamp is None:
return None
return self.outcome_timestamp - self.start_time
def prepare_for_next_attempt(self):
self.outcome = None
self.outcome_timestamp = None
self.attempt_number += 1
self.next_action = None
def set_result(self, val):
ts = _utils.now()
fut = Future(self.attempt_number)
fut.set_result(val)
self.outcome, self.outcome_timestamp = fut, ts
def set_exception(self, exc_info):
ts = _utils.now()
fut = Future(self.attempt_number)
_utils.capture(fut, exc_info)
self.outcome, self.outcome_timestamp = fut, ts
if asyncio:
from tenacity._asyncio import AsyncRetrying
if tornado:
from tenacity.tornadoweb import TornadoRetrying