100 lines
2.6 KiB
Python
100 lines
2.6 KiB
Python
# piker: trading gear for hackers
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# Copyright (C) Tyler Goodlet (in stewardship for pikers)
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# This program is free software: you can redistribute it and/or modify
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# it under the terms of the GNU Affero General Public License as published by
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# the Free Software Foundation, either version 3 of the License, or
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# (at your option) any later version.
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU Affero General Public License for more details.
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# You should have received a copy of the GNU Affero General Public License
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# along with this program. If not, see <https://www.gnu.org/licenses/>.
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'''
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Cacheing apis and toolz.
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'''
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from collections import OrderedDict
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from typing import (
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Awaitable,
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Callable,
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ParamSpec,
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TypeVar,
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)
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from .log import get_logger
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log = get_logger(__name__)
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T = TypeVar("T")
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P = ParamSpec("P")
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# TODO: move this to `tractor.trionics`..
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# - egs. to replicate for tests: https://github.com/aio-libs/async-lru#usage
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# - their suite as well:
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# https://github.com/aio-libs/async-lru/tree/master/tests
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# - asked trio_util about it too:
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# https://github.com/groove-x/trio-util/issues/21
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def async_lifo_cache(
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maxsize=128,
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# NOTE: typing style was learned from:
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# https://stackoverflow.com/a/71132186
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) -> Callable[
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Callable[P, Awaitable[T]],
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Callable[
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Callable[P, Awaitable[T]],
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Callable[P, Awaitable[T]],
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],
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]:
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'''
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Async ``cache`` with a LIFO policy.
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Implemented my own since no one else seems to have
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a standard. I'll wait for the smarter people to come
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up with one, but until then...
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NOTE: when decorating, due to this simple/naive implementation, you
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MUST call the decorator like,
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.. code:: python
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@async_lifo_cache()
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async def cache_target():
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'''
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cache = OrderedDict()
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def decorator(
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fn: Callable[P, Awaitable[T]],
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) -> Callable[P, Awaitable[T]]:
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async def decorated(
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*args: P.args,
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**kwargs: P.kwargs,
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) -> T:
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key = args
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try:
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return cache[key]
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except KeyError:
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if len(cache) >= maxsize:
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# discard last added new entry
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cache.popitem()
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# call underlying
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cache[key] = await fn(
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*args,
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**kwargs,
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)
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return cache[key]
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return decorated
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return decorator
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