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bdd94b1f8a
* Add prioritization to webhook/notifications queue * Add missing code * Missing license header * Fix argument * Use redis pipeline * Update license header
63 lines
2.8 KiB
Python
63 lines
2.8 KiB
Python
#
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# This file is part of pretix (Community Edition).
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#
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# Copyright (C) 2014-2020 Raphael Michel and contributors
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# Copyright (C) 2020-today pretix GmbH and contributors
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#
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# This program is free software: you can redistribute it and/or modify it under the terms of the GNU Affero General
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# Public License as published by the Free Software Foundation in version 3 of the License.
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#
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# ADDITIONAL TERMS APPLY: Pursuant to Section 7 of the GNU Affero General Public License, additional terms are
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# applicable granting you additional permissions and placing additional restrictions on your usage of this software.
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# Please refer to the pretix LICENSE file to obtain the full terms applicable to this work. If you did not receive
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# this file, see <https://pretix.eu/about/en/license>.
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#
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# This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied
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# warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
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# details.
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#
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# You should have received a copy of the GNU Affero General Public License along with this program. If not, see
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# <https://www.gnu.org/licenses/>.
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#
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from django.conf import settings
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THRESHOLD_DOWNGRADE_TO_MID = 50
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THRESHOLD_DOWNGRADE_TO_LOW = 250
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def get_task_priority(shard, organizer_id):
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"""
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This is an attempt to build a simple "fair-use" policy for webhooks and notifications. The problem is that when
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one organizer creates e.g. 20,000 orders through the API, that might schedule 20,000 webhooks and every other
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organizer will need to wait for these webhooks to go through.
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We try to fix that by building three queues: high-prio, mid-prio, and low-prio. Every organizer starts in the
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high-prio queue, and all their tasks are routed immediately. Once an organizer submits more than X jobs of a
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certain type per minute, they get downgraded to the mid-prio queue, and then – if they submit even more – to the
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low-prio queue. That way, if another organizer has "regular usage", they are prioritized over the organizer with
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high load.
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"""
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from django_redis import get_redis_connection
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if not settings.HAS_REDIS:
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return settings.PRIORITY_CELERY_HIGH
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# We use redis directly instead of the Django cache API since the Django cache API does not support INCR for
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# nonexistant keys
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rc = get_redis_connection("redis")
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cache_key = f"pretix:task_priority:{shard}:{organizer_id}"
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# Make sure counters expire after a while when not used
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p = rc.pipeline()
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p.incr(cache_key)
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p.expire(cache_key, 60)
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new_counter = p.execute()[0]
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if new_counter >= THRESHOLD_DOWNGRADE_TO_LOW:
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return settings.PRIORITY_CELERY_LOW
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elif new_counter >= THRESHOLD_DOWNGRADE_TO_MID:
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return settings.PRIORITY_CELERY_MID
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else:
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return settings.PRIORITY_CELERY_HIGH
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