mirror of https://gitlab.crans.org/bde/nk20
65 lines
2.0 KiB
Python
65 lines
2.0 KiB
Python
# Copyright (C) 2018-2020 by BDE ENS Paris-Saclay
|
|
# SPDX-License-Identifier: GPL-3.0-or-later
|
|
|
|
from functools import lru_cache
|
|
from time import time
|
|
|
|
from django.conf import settings
|
|
from django.contrib.sessions.models import Session
|
|
from note_kfet.middlewares import get_current_session
|
|
|
|
|
|
def memoize(f):
|
|
"""
|
|
Memoize results and store in sessions
|
|
|
|
This decorator is useful for permissions: they are loaded once needed, then stored for next calls.
|
|
The storage is contained with sessions since it depends on the selected mask.
|
|
"""
|
|
sess_funs = {}
|
|
last_collect = time()
|
|
|
|
def collect():
|
|
"""
|
|
Clear cache of results when sessions are invalid, to flush useless data.
|
|
This function is called every minute.
|
|
"""
|
|
nonlocal sess_funs
|
|
|
|
new_sess_funs = {}
|
|
for sess_key in sess_funs:
|
|
if Session.objects.filter(session_key=sess_key).exists():
|
|
new_sess_funs[sess_key] = sess_funs[sess_key]
|
|
sess_funs = new_sess_funs
|
|
|
|
def func(*args, **kwargs):
|
|
if settings.DEBUG:
|
|
# Don't memoize in DEBUG mode
|
|
return f(*args, **kwargs)
|
|
|
|
nonlocal last_collect
|
|
|
|
if time() - last_collect > 60:
|
|
# Clear cache
|
|
collect()
|
|
last_collect = time()
|
|
|
|
# If there is no session, then we don't memoize anything.
|
|
sess = get_current_session()
|
|
if sess is None or sess.session_key is None:
|
|
return f(*args, **kwargs)
|
|
|
|
sess_key = sess.session_key
|
|
if sess_key not in sess_funs:
|
|
# lru_cache makes the job of memoization
|
|
# We store only the 512 latest data per session. It has to be enough.
|
|
sess_funs[sess_key] = lru_cache(512)(f)
|
|
try:
|
|
return sess_funs[sess_key](*args, **kwargs)
|
|
except TypeError: # For add permissions, objects are not hashable (not yet created). Don't memoize this case.
|
|
return f(*args, **kwargs)
|
|
|
|
func.func_name = f.__name__
|
|
|
|
return func
|