Source code for backoff_utils._decorator

# -*- coding: utf-8 -*-


Implements the ``@apply_backoff()`` decorator which can be applied to
function/method calls and retries on failure based on arguments passed to the
``backoff()`` function.

from functools import wraps

from backoff_utils._backoff import backoff

[docs]def apply_backoff(strategy = None, max_tries = None, max_delay = None, catch_exceptions = None, on_failure = None, on_success = None): """Decorator that applies a backoff strategy to a decorated function/method. :param strategy: The :class:`BackoffStrategy` to use when determining the delay between retry attempts. If :class:`None <python:None>`, defaults to :class:`Exponential <Exponential>`. :type strategy: :class:`BackoffStrategy` :param max_tries: The maximum number of times to attempt the call. If :class:`None <python:None>`, will apply an environment variable ``BACKOFF_DEFAULT_TRIES``. If that environment variable is not set, will apply a default of ``3``. :type max_tries: :class:`int <python:int>` / :class:`None <python:None>` :param max_delay: The maximum number of seconds to wait befor giving up once and for all. If :class:`None <python:None>`, will apply an environment variable ``BACKOFF_DEFAULT_DELAY`` if that environment variable is set. If it is not set, will not apply a max delay at all. :type max_delay: :class:`None <python:None>` / class:`int <python:int>` :param catch_exceptions: The ``type(exception)`` to catch and retry. If :class:`None <python:None>`, will catch all exceptions. Defaults to :class:`None <python:None>`. .. caution:: The iterable must contain one or more types of exception *instances*, and not class objects. For example: .. code-block:: python # GOOD: catch_exceptions = (type(ValueError()), type(TypeError())) # BAD: catch_exceptions = (type(ValueError), type(ValueError)) # BAD: catch_exceptions = (ValueError, TypeError) # BAD: catch_exceptions = (ValueError(), TypeError()) :type catch_exceptions: iterable of form ``[type(exception()), ...]`` :param on_failure: The :class:`exception <python:Exception>` or function to call when all retry attempts have failed. If :class:`None <python:None>`, will raise the last-caught :class:`Exception <python:Exception>`. If an :class:`Exception <python:Exception>`, will raise the exception with the same message as the last-caught exception. If a function, will call the function and pass the last-raised exception, its message, and stacktrace to the function. Defaults to :class:`None <python:None>`. :type on_failure: :class:`Exception <python:Exception>` / function / :class:`None <python:None>` :param on_success: The function to call when the operation was successful. The function receives the result of the decorated function, and is called before that result is returned to whatever code called the decorated function. If :class:`None <python:None>`, will just return the result of the decorated function without calling a handler. Defaults to :class:`None <python:None>`. :type on_success: callable / :class:`None <python:None>` Example: .. code:: python @apply_backoff(strategy = strategies.ExponentialBackoff, max_tries = 5, max_delay = 30) def some_function(arg1, arg2, kwarg1 = None): pass result = some_function('value1', 'value2', kwarg1 = 'value3') """ def real_decorator(func): @wraps(func) def wrapper(*args, **kwargs): return backoff(to_execute = func, args = args, kwargs = kwargs, strategy = strategy, max_tries = max_tries, max_delay = max_delay, catch_exceptions = catch_exceptions, on_failure = on_failure, on_success = on_success) return wrapper return real_decorator