CASSPYTHON-18: removed obsolete check for python version > 3.7+

[bschoening]

No description provided.

[Copilot]

Pull request overview

Removes an obsolete Python version guard around the Eventlet + ThreadPoolExecutor workaround, simplifying executor selection now that the driver targets newer Python versions.

Changes:

• Simplified _create_thread_pool_executor by removing the redundant sys.version_info check.
• Always attempts to detect Eventlet usage and switches to futurist.GreenThreadPoolExecutor when needed.

---

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[absurdfarce]

There are a number of other spots where sys.version_info is consulted to make decisions about functionality. It's true that all the rest of them are in test code but it might be a good idea to fix all of them in one go anyway:

$ rg version_info
tests/unit/advanced/test_insights.py
66:        if sys.version_info > (3,):

tests/integration/advanced/graph/fluent/__init__.py
588:        if sys.version_info >= (3, 0):

tests/unit/test_policies.py
1297:        if sys.version_info >= (3, 11):

docs/api/cassandra.rst
6:.. data:: __version_info__

tests/unit/test_row_factories.py
31:NAMEDTUPLE_CREATION_BUG = sys.version_info >= (3,) and sys.version_info < (3, 7)

cassandra/cluster.py
1427:        if sys.version_info[0] >= 3 and sys.version_info[1] >= 7:

tests/integration/standard/test_metadata.py
1095:        if sys.version_info[0:2] != (2, 7):

tests/integration/cqlengine/columns/test_validation.py
615:        if sys.version_info < (3, 1):
739:        if sys.version_info < (3, 1):

tests/integration/cqlengine/base.py
51:    if sys.version_info > (3, 0):

I can make the changes and push a commit to this branch if that's useful.

[absurdfarce]

We should perhaps change this usage to be more consistent with the current state of things on two fronts:

1. Remove the conditionals on Python versions
2. Recommend against eventlet anyways

Maybe something more like the following?

When using eventlet the concurrent.futures.ThreadPoolExecutor will hang indefinitely. If you want to use the eventlet reactor, you need to install the futurist package to allow the driver to use the GreenThreadPoolExecutor. See eventlet/eventlet#508 for more details.

Note that the eventlet reactor is deprecated and will be removed in 3.31.0. We strongly recommend using the asyncore or libev reactors for production code.

[absurdfarce]

Hmmm, I'm not even 💯 sure we need this at all. It looks as if eventlet fixed this issue here and that this code was released in version 0.26.0. That version went out in July of 2020 so it's hard to imagine anyone getting an old enough version of eventlet for this to actually be a problem if they did a requirements install today.

[bschoening]

@absurdfarce there are two left which I didn't fully understand, if you could update the PR with changes to those two, that would be terrific.

integration/standard/test_metadata.py:    if sys.version_info[0:2] != (2, 7):
unit/test_row_factories.p: NAMEDTUPLE_CREATION_BUG = sys.version_info >= (3,) and sys.version_info < (3, 7)

[bschoening]

Gemini suggest the following:

@greaterthancass20
def test_export_keyspace_schema_udts(self):
"""
Test udt exports (Modernized for Python 3.10+)
"""
# We still need this: UDTs require Native Protocol v3+
if PROTOCOL_VERSION < 3:
raise unittest.SkipTest(
"Protocol 3.0+ is required for UDT change events, currently testing against %r"
% (PROTOCOL_VERSION,))

cluster = TestCluster()
session = cluster.connect()

# 1. Setup Schema
session.execute("""
    CREATE KEYSPACE export_udts
    WITH replication = {'class': 'SimpleStrategy', 'replication_factor': '1'}
    AND durable_writes = true;
""")
session.execute("CREATE TYPE export_udts.street (street_number int, street_name text)")
session.execute("CREATE TYPE export_udts.zip (zipcode int, zip_plus_4 int)")
session.execute("""
    CREATE TYPE export_udts.address (
        street_address frozen<street>,
        zip_code frozen<zip>)
""")
session.execute("""
    CREATE TABLE export_udts.users (
        user text PRIMARY KEY,
        addresses map<text, frozen<address>>)
""")

# 2. Re-trigger a metadata refresh to ensure the driver has captured the schema
cluster.metadata.refresh_keyspace_metadata('export_udts')
keyspace_meta = cluster.metadata.keyspaces['export_udts']
export_string = keyspace_meta.export_as_string()

# 3. Modern Assertions
# In 3.10+, dict order is stable. We check for core components.
expected_parts = [
    "CREATE KEYSPACE export_udts",
    "'class': 'SimpleStrategy'",
    "'replication_factor': '1'",
    "CREATE TYPE export_udts.street",
    "CREATE TYPE export_udts.zip",
    "CREATE TYPE export_udts.address",
    "CREATE TABLE export_udts.users"
]

for part in expected_parts:
    self.assertIn(part, export_string)

# 4. Verify UDT Nesting Order (Address must come after Street/Zip)
street_idx = export_string.find("CREATE TYPE export_udts.street")
zip_idx = export_string.find("CREATE TYPE export_udts.zip")
address_idx = export_string.find("CREATE TYPE export_udts.address")

self.assertTrue(street_idx < address_idx, "Street UDT must be defined before Address UDT")
self.assertTrue(zip_idx < address_idx, "Zip UDT must be defined before Address UDT")

[absurdfarce]

The underlying problem is fixed in Python 3.7 (see PYTHON-893 for more on that point) so we should no longer have any case in which NAMEDTUPLE_CREATION_BUG eval's to true.

[absurdfarce]

Three changes above were minor fixes to address some deprecation warnings noted when running the test via Python 3.10:

tests/integration/standard/test_metadata.py:1591
  /home/mersault/work/git/python-driver/tests/integration/standard/test_metadata.py:1591: DeprecationWarning: invalid escape sequence '\('
	self.assertRegex(fn_meta.as_cql_query(), "CREATE FUNCTION.*%s\(\) .*" % kwargs['name'])

tests/integration/standard/test_metadata.py:1639
  /home/mersault/work/git/python-driver/tests/integration/standard/test_metadata.py:1639: DeprecationWarning: invalid escape sequence '\)'
	self.assertRegex(fn_meta.as_cql_query(), "CREATE FUNCTION.*\) CALLED ON NULL INPUT RETURNS .*")

tests/integration/standard/test_metadata.py:1644
  /home/mersault/work/git/python-driver/tests/integration/standard/test_metadata.py:1644: DeprecationWarning: invalid escape sequence '\)'
	self.assertRegex(fn_meta.as_cql_query(), "CREATE FUNCTION.*\) RETURNS NULL ON NULL INPUT RETURNS .*")

[absurdfarce]

This is certainly possible, but if we find ourselves in a situation where our output changes because a particular version is handling dictionary keys differently I would much rather know that (by way of a failing test) than silently skipping the test in question.

[absurdfarce]

@bschoening Fixes should now be in place for test_row_factories.py and test_metadata.py. I'm going to run Jenkins against the current state of this build to confirm there aren't any unexpected regressions but I think we're getting pretty close.