Include Rate Limiting Support

[codylandry]

I wanted to check in and see if the maintainers thought it would be a good feature to add to uplink. The idea is that you can specify a requests/time period and the consumer would never make request faster than that. It would be up to the user to specify a rate somewhat lower than the actual limit for the api they're wrapping. I could see an issue that would make it unnecessary to add this feature, being that you can only limit the requests a for a single instance. Just wanted to put it up for consideration.

[prkumar]

The ratelimit decorator should be available in v0.8.0. After I merge #132, I'll create a new alpha release v0.8.0a1 in case you wan't to try it out before the official release. To install this alpha release with pip, do:

$ pip install --pre uplink

Here's some documentation for the decorator. (I'll also be soon adding a section to the quickstart about this feature). Notably, this decorator can be used like the other decorators, such as @timeout or @headers:

class GitHub(uplink.Consumer):
    @uplink.ratelimit(calls=15, period=900)  # limit of 15 calls every 15 minutes
    @uplink.get("/users/{user}")
    def get_user(self, user):
        pass

If you get the chance to try it out, let me know if you also have any feedback!

CC: @codylandry

[prkumar]

I just released an new alpha version, v0.8.0a2, with some updates to this decorator. If you were testing the previous alpha, please update:

$ pip install --pre -U uplink

Also, I've added a section to the quickstart to help get started with using this decorator: https://uplink.readthedocs.io/en/latest/user/quickstart.html#client-side-rate-limiting

CC: @codylandry