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Fix quota cache mixup (#3539)

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Co-authored-by: Richard Schreiber <schreiber@rami.io>
This commit is contained in:
Raphael Michel
2023-08-23 10:09:50 +02:00
committed by GitHub
parent 9bd3444aad
commit 0c96f758a8
7 changed files with 126 additions and 15 deletions
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27
src/pretix/base/services/quotas.py
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@@ -24,13 +24,13 @@ import time
from collections import Counter, defaultdict
from itertools import zip_longest
import django_redis
from django.conf import settings
from django.db import models
from django.db.models import (
Case, Count, F, Func, Max, OuterRef, Q, Subquery, Sum, Value, When,
)
from django.utils.timezone import now
from django_redis import get_redis_connection
from pretix.base.models import (
CartPosition, Checkin, Order, OrderPosition, Quota, Voucher,
@@ -102,6 +102,12 @@ class QuotaAvailability:
self.count_waitinglist = defaultdict(int)
self.count_cart = defaultdict(int)
self._cache_key_suffix = ""
if not self._count_waitinglist:
self._cache_key_suffix += ":nocw"
if self._ignore_closed:
self._cache_key_suffix += ":igcl"
self.sizes = {}
def queue(self, *quota):
@@ -121,17 +127,14 @@ class QuotaAvailability:
if self._full_results:
raise ValueError("You cannot combine full_results and allow_cache.")
elif not self._count_waitinglist:
raise ValueError("If you set allow_cache, you need to set count_waitinglist.")
elif settings.HAS_REDIS:
rc = get_redis_connection("redis")
rc = django_redis.get_redis_connection("redis")
quotas_by_event = defaultdict(list)
for q in [_q for _q in self._queue if _q.id in quota_ids_set]:
quotas_by_event[q.event_id].append(q)
for eventid, evquotas in quotas_by_event.items():
d = rc.hmget(f'quotas:{eventid}:availabilitycache', [str(q.pk) for q in evquotas])
d = rc.hmget(f'quotas:{eventid}:availabilitycache{self._cache_key_suffix}', [str(q.pk) for q in evquotas])
for redisval, q in zip(d, evquotas):
if redisval is not None:
data = [rv for rv in redisval.decode().split(',')]
@@ -164,12 +167,12 @@ class QuotaAvailability:
if not settings.HAS_REDIS or not quotas:
return
rc = get_redis_connection("redis")
rc = django_redis.get_redis_connection("redis")
# We write the computed availability to redis in a per-event hash as
#
# quota_id -> (availability_state, availability_number, timestamp).
#
# We store this in a hash instead of inidividual values to avoid making two many redis requests
# We store this in a hash instead of individual values to avoid making too many redis requests
# which would introduce latency.
# The individual entries in the hash are "valid" for 120 seconds. This means in a typical peak scenario with
@@ -179,16 +182,16 @@ class QuotaAvailability:
# these quotas. We choose 10 seconds since that should be well above the duration of a write.
lock_name = '_'.join([str(p) for p in sorted([q.pk for q in quotas])])
if rc.exists(f'quotas:availabilitycachewrite:{lock_name}'):
if rc.exists(f'quotas:availabilitycachewrite:{lock_name}{self._cache_key_suffix}'):
return
rc.setex(f'quotas:availabilitycachewrite:{lock_name}', '1', 10)
rc.setex(f'quotas:availabilitycachewrite:{lock_name}{self._cache_key_suffix}', '1', 10)
update = defaultdict(list)
for q in quotas:
update[q.event_id].append(q)
for eventid, quotas in update.items():
rc.hmset(f'quotas:{eventid}:availabilitycache', {
rc.hmset(f'quotas:{eventid}:availabilitycache{self._cache_key_suffix}', {
str(q.id): ",".join(
[str(i) for i in self.results[q]] +
[str(int(time.time()))]
@@ -197,7 +200,7 @@ class QuotaAvailability:
# To make sure old events do not fill up our redis instance, we set an expiry on the cache. However, we set it
# on 7 days even though we mostly ignore values older than 2 monites. The reasoning is that we have some places
# where we set allow_cache_stale and use the old entries anyways to save on performance.
rc.expire(f'quotas:{eventid}:availabilitycache', 3600 * 24 * 7)
rc.expire(f'quotas:{eventid}:availabilitycache{self._cache_key_suffix}', 3600 * 24 * 7)
# We used to also delete item_quota_cache:* from the event cache here, but as the cache
# gets more complex, this does not seem worth it. The cache is only present for up to