Async CacheControl for aiohttp

Requires Python3.6+

Note: Library is still under development, there might be a lot of bugs.

For contributing see development_notes.md as a starting guide

What and why

There is a good and simple library CacheControl written for python requests library. And there is nothing similar for aiohttp. "Async CacheControl" project strives to cover this hole.

Usage

import asyncio
from acachecontrol import AsyncCache, AsyncCacheControl


async def main():
    cache = AsyncCache(config={"sleep_time": 0.2})
    # `AsyncCache()` with default configuration is used
    # if `cache` not provided
    async with AsyncCacheControl(cache=cache) as cached_sess:
        async with cached_sess.get('http://example.com') as resp:
            resp_text = await resp.text()
            print(resp_text)


asyncio.run(main())

Extending or creating new classes

It is possible to use any cache backend, which should implement OrderedDict interfaces: __contains__, __len__, __getitem__, __setitem__, get, pop, popitem, move_to_end:

class CustomCacheBackend():
    def __init__(self):
        self.item_order = []
        self.storage = {}

    def __contains__(self, key):
        return key in self.storage

    def __len__(self):
        return len(self.storage)

    def __getitem__(self, key):
        return self.storage[key]

    def __setitem__(self, key, value):
        self.storage[key] = value
        self.item_order.append(key)

    def get(self, key):
        return self.storage.get(key)

    def pop(self, key):
        self.item_order.remove(key)
        return self.storage.pop(key)

    def move_to_end(self, key):
        last_index = len(self.item_order) - 1
        key_index = self.item_order.index(key)
        while key_index < last_index:
            self.item_order[key_index] = self.item_order[key_index+1]
            key_index += 1
        self.item_order[last_index] = key

    def popitem(self, last=True):
        key = self.item_order.pop() if last else self.item_order.pop(0)
        value = self.storage.pop(key)
        return value

Then you can use it in AsyncCache:

import asyncio
from acachecontrol import AsyncCache, AsyncCacheControl


async def main():
    cache = AsyncCache(cache_backend=CustomCacheBackend())
    async with AsyncCacheControl(cache=cache) as cached_sess:
        async with cached_sess.get('http://example.com') as resp:
            resp_text = await resp.text()
            print(resp_text)


asyncio.run(main())

Similarly, you can replace RequestContextManager (assume its implementation in module custom_implementations):

import asyncio
from acachecontrol import AsyncCache, AsyncCacheControl

from custom_implementations import CustomRequestContextManager


async def main():
    async with AsyncCacheControl(request_context_manager_cls=CustomRequestContextManager) as cached_sess:
        async with cached_sess.get('http://example.com') as resp:
            resp_text = await resp.text()
            print(resp_text)


asyncio.run(main())