trythatagain
This provides decorators for super simple function/method call retries when an exception is raised.
Installation
pip install trythatagainExamples
Here's a simple use case: querying the AWS API, knowing you might hit API limits.
from trythatagain import retry
@retry
def find_ebs_volumes(unattached=True, no_snapshots=True):
...
try:
find_ebs_volumes()
except CaughtException as e:
print('Failed to list EBS volumes')
print(e.caught_exception)This will retry calling func three times. If was not successful in calling the function without an exception, it will re-raise the exception as CaughtException, with the original exception available at the attribute caught_exception.
Retry as many times as times as necessary:
from trythatagain import retry
@retry(retries=5)
def try_five_times():
raise Exception('This always fails')
@retry(retries=0)
def retry_forever():
raise Exception('Terrible waste of CPU cycles')Raise immediately on specific exceptions:
@retry(raise_for=ValueError)
def update_cache():
...Suppress re-raising exceptions:
@retry(reraise=False)
def reload_user_data():
...There's also exponential and linear backoff retries things like cooling down after hitting API limits. In fact, AWS recommends exponential backoff to deal with API limits.
# waits 1 second, then 4, then 9, etc.
@retry_exp_backoff(unit=MILLISECONDS)
def update_instance_tags():
...
@retry_linear_backoff(unit=SECONDS)
def scrape_url():
...Custom wait functions are also possible:
def fixed(i, unit):
time.sleep(5 * unit)
@retry(wait_func=fixed, unit=MILLISECONDS)
def func():
...
