ratelimit 2.1.0

API rate limit decorator

APIs are a very common way to interact with web services. As the need to consume data grows, so does the number of API calls necessary to remain up to date with data sources. However many API providers constrain developers from making too many API calls. This is know as rate limiting and in a worst case scenario your application can be banned from making further API calls if it abuses these limits.

This packages introduces a method decorator preventing a method from being called more than once within a given time period. This should prevent API providers from banning your applications by conforming to set rate limits.

Installation

PyPi

To install ratelimit, simply:

$ pip install ratelimit

GitHub

Installing the latest version from Github:

$ git clone https://github.com/tomasbasham/ratelimit
$ cd ratelimit
$ python setup.py install

Usage

To use this package you simply have to declare the decorator before the method you wish to rate limit:

from ratelimit import limits

import requests

FIFTEEN_MINUTES = 900

@limits(calls=15, period=FIFTEEN_MINUTES)
def call_api(url):
    response = requests.get(url)

    if response.status_code != 200:
        raise Exception('API response: {}'.format(response.status_code))
    return response

This method makes a call to our API. Note that this method has been implemented with a decorator enforcing that it may only be called 15 times every 15 minutes.

The arguments passed into the decorator impose the number of method invocation allowed over a specified time period (in seconds). If no time period is specified then it defaults to 15 minutes (the time window imposed by Twitter).

If a decorated method is called more times than that allowed within the specified time period then a ratelimit.RateLimitException is raised. This may be used to implement a retry strategy such as an expoential backoff

from ratelimit import limits, RateLimitException
from backoff import on_exception, expo

import requests

FIFTEEN_MINUTES = 900

@on_exception(expo, RateLimitException, max_tries=8)
@limits(calls=15, period=FIFTEEN_MINUTES)
def call_api(url):
    response = requests.get(url)

    if response.status_code != 200:
        raise Exception('API response: {}'.format(response.status_code))
    return response

Alternatively to cause the current thread to sleep until the specified time period has ellapsed and then retry the function use the sleep_and_retry decorator. This ensure that every function invocation is successful at the cost of halting the thread.

from ratelimit import limits, sleep_and_retry

import requests

FIFTEEN_MINUTES = 900

@sleep_and_retry
@limits(calls=15, period=FIFTEEN_MINUTES)
def call_api(url):
    response = requests.get(url)

    if response.status_code != 200:
        raise Exception('API response: {}'.format(response.status_code))
    return response

Contributing

1. Fork it (https://github.com/tomasbasham/ratelimit/fork)

2. Create your feature branch (git checkout -b my-new-feature)

3. Commit your changes (git commit -am ‘Add some feature’)

4. Push to the branch (git push origin my-new-feature)

5. Create a new Pull Request