50 lines
1.5 KiB
Python
50 lines
1.5 KiB
Python
# piker: trading gear for hackers
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# Copyright (C) 2018-present Tyler Goodlet (in stewardship of piker0)
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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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Async utils no one seems to have built into a core lib (yet).
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"""
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from collections import OrderedDict
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def async_lifo_cache(maxsize=128):
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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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"""
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cache = OrderedDict()
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def decorator(fn):
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async def wrapper(*args):
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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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# do it
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cache[key] = await fn(*args)
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return cache[key]
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return wrapper
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return decorator
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