mirror of
https://github.com/retspen/webvirtcloud
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cd2dd517b7
With one owner per VM, the VM page and a user's page counted the VM's owners and then added one in separate steps, so two owners added at the same moment both found the VM without one, and it got two. The check and the insert now run in one transaction that holds the ownership lock (PostgreSQL's advisory lock; SQLite's IMMEDIATE transactions already serialize them): the second waits for the first and is refused. The audit row is written after the transaction, so a failure keeps its row.
78 lines
3.2 KiB
Python
78 lines
3.2 KiB
Python
"""With one owner per VM, two owners added at the same moment, from the VM
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page or a user's page: the second waits for the first and is refused. SQLite's
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IMMEDIATE transactions serialize them; PostgreSQL takes the ownership lock."""
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import threading
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import time
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from unittest.mock import patch
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from accounts.models import UserInstance
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from appsettings.models import AppSettings
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from computes.models import Compute
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from django.contrib.auth import get_user_model
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from django.db import connection
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from django.test import Client, TransactionTestCase
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from django.urls import reverse
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from instances.models import Instance
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UUID = "55555555-5555-5555-5555-555555555555"
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class OwnerRaceTests(TransactionTestCase):
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def setUp(self):
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AppSettings.objects.update_or_create(
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key="ALLOW_INSTANCE_MULTIPLE_OWNER",
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defaults={"name": "Multiple owners", "value": "False", "choices": "True,False"},
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)
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users = get_user_model().objects
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self.admin = users.create_superuser("race-admin", "race@example.com", "pw")
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self.bob, self.carol = users.create_user("bob"), users.create_user("carol")
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compute = Compute.objects.create(name="c1", hostname="127.0.0.1", login="", password="", type=4)
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self.vm = Instance.objects.create(compute=compute, name="vm", uuid=UUID)
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def post(self, url, data):
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client = Client()
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client.force_login(self.admin)
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try:
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self.answers.append(client.post(url, data).status_code)
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finally:
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connection.close()
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def test_from_the_vm_page(self):
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add = reverse("instances:add_owner", args=[self.vm.pk])
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self.race(lambda: self.post(add, {"user_id": self.bob.pk}),
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lambda: self.post(add, {"user_id": self.carol.pk}))
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def test_from_the_vm_page_and_a_user_s_page(self):
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add = reverse("instances:add_owner", args=[self.vm.pk])
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create = reverse("accounts:user_instance_create", args=[self.carol.pk])
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self.race(lambda: self.post(add, {"user_id": self.bob.pk}),
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lambda: self.post(create, {"user": self.carol.pk, "instance": self.vm.pk}))
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def race(self, first, second):
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"""first stops after its check, with its transaction open, while
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second runs; second must then find first's owner. Both answer: the
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VM page redirects, a refused user's page shows the form again."""
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self.answers = []
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checked, go = threading.Event(), threading.Event()
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real = UserInstance.objects.get_or_create
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def slow_get_or_create(**kwargs):
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checked.set()
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go.wait(10)
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return real(**kwargs)
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with patch.object(UserInstance.objects, "get_or_create", slow_get_or_create):
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a = threading.Thread(target=first)
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a.start()
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self.assertTrue(checked.wait(10))
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b = threading.Thread(target=second)
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b.start()
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time.sleep(1) # second would add its owner now if nothing held it
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go.set()
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a.join(30)
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b.join(30)
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self.assertEqual(len(self.answers), 2)
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self.assertTrue(set(self.answers) <= {200, 302}, self.answers)
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self.assertEqual(list(UserInstance.objects.values_list("user__username", flat=True)), ["bob"])
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