102 lines
3.5 KiB
Python
102 lines
3.5 KiB
Python
"""Tests for util.db module."""
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import ddt
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import threading
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import time
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import unittest
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from django.contrib.auth.models import User
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from django.db import connection, IntegrityError
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from django.db.transaction import commit_on_success, TransactionManagementError
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from django.test import TransactionTestCase
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from util.db import commit_on_success_with_read_committed
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@ddt.ddt
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class TransactionIsolationLevelsTestCase(TransactionTestCase):
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"""
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Tests the effects of changing transaction isolation level to READ COMMITTED instead of REPEATABLE READ.
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Note: This TestCase only works with MySQL.
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To run it on devstack:
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1. Add TEST_RUNNER = 'django_nose.NoseTestSuiteRunner' to envs/devstack.py
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2. Run "./manage.py lms --settings=devstack test util.tests.test_db"
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"""
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@ddt.data(
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(commit_on_success, IntegrityError, None, True),
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(commit_on_success_with_read_committed, type(None), False, True),
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)
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@ddt.unpack
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def test_concurrent_requests(self, transaction_decorator, exception_class, created_in_1, created_in_2):
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"""
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Test that when isolation level is set to READ COMMITTED get_or_create()
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for the same row in concurrent requests does not raise an IntegrityError.
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"""
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if connection.vendor != 'mysql':
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raise unittest.SkipTest('Only works on MySQL.')
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class RequestThread(threading.Thread):
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""" A thread which runs a dummy view."""
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def __init__(self, delay, **kwargs):
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super(RequestThread, self).__init__(**kwargs)
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self.delay = delay
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self.status = {}
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@transaction_decorator
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def run(self):
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"""A dummy view."""
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try:
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try:
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User.objects.get(username='student', email='student@edx.org')
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except User.DoesNotExist:
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pass
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else:
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raise AssertionError('Did not raise User.DoesNotExist.')
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if self.delay > 0:
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time.sleep(self.delay)
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__, created = User.objects.get_or_create(username='student', email='student@edx.org')
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except Exception as exception: # pylint: disable=broad-except
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self.status['exception'] = exception
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else:
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self.status['created'] = created
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thread1 = RequestThread(delay=1)
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thread2 = RequestThread(delay=0)
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thread1.start()
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thread2.start()
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thread2.join()
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thread1.join()
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self.assertIsInstance(thread1.status.get('exception'), exception_class)
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self.assertEqual(thread1.status.get('created'), created_in_1)
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self.assertIsNone(thread2.status.get('exception'))
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self.assertEqual(thread2.status.get('created'), created_in_2)
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def test_transaction_nesting(self):
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"""Test that the decorator raises an error if there are already more than 1 levels of nested transactions."""
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if connection.vendor != 'mysql':
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raise unittest.SkipTest('Only works on MySQL.')
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def do_nothing():
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"""Just return."""
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return
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commit_on_success_with_read_committed(do_nothing)()
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with commit_on_success():
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commit_on_success_with_read_committed(do_nothing)()
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with self.assertRaises(TransactionManagementError):
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with commit_on_success():
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with commit_on_success():
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commit_on_success_with_read_committed(do_nothing)()
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