CASSPYTHON-13: Remove stale EventletConnection reference in _create_thread_pool_executor

This code path in cassandra/cluster.py was not part of the original
upstream removal since it doesn't exist upstream; it's fork-specific.
With eventletreactor deleted, the import always failed and the method
always fell back to a plain ThreadPoolExecutor, so drop the dead branch.

Author: mykaul

CONTRIBUTING.rst

@@ -73,8 +73,7 @@ Running Unit Tests
 Unit tests can be run like so::
 
     uv run pytest tests/unit
-    EVENT_LOOP_MANAGER=gevent uv run pytest tests/unit/io/test_geventreactor.py
-    EVENT_LOOP_MANAGER=eventlet uv run pytest tests/unit/io/test_eventletreactor.py
+    EVENT_LOOP_MANAGER=asyncio uv run pytest tests/unit/io/test_asyncioreactor.py
 
 You can run a specific test method like so::
 

cassandra/cluster.py

@@ -37,7 +37,6 @@
 import re
 import queue
 import socket
-import sys
 import time
 from threading import Lock, RLock, Thread, Event
 import uuid
@@ -1548,39 +1547,12 @@ def _resolve_hostnames(self):
 
     def _create_thread_pool_executor(self, **kwargs):
         """
-        Create a ThreadPoolExecutor for the cluster. In most cases, the built-in
-        `concurrent.futures.ThreadPoolExecutor` is used.
-
-        Python 3.7+ and Eventlet cause the `concurrent.futures.ThreadPoolExecutor`
-        to hang indefinitely. In that case, the user needs to have the `futurist`
-        package so we can use the `futurist.GreenThreadPoolExecutor` class instead.
+        Create a ThreadPoolExecutor for the cluster.
 
         :param kwargs: All keyword args are passed to the ThreadPoolExecutor constructor.
         :return: A ThreadPoolExecutor instance.
         """
-        tpe_class = ThreadPoolExecutor
-        if sys.version_info[0] >= 3 and sys.version_info[1] >= 7:
-            try:
-                from cassandra.io.eventletreactor import EventletConnection
-                is_eventlet = issubclass(self.connection_class, EventletConnection)
-            except:
-                # Eventlet is not available or can't be detected
-                return tpe_class(**kwargs)
-
-            if is_eventlet:
-                try:
-                    from futurist import GreenThreadPoolExecutor
-                    tpe_class = GreenThreadPoolExecutor
-                except ImportError:
-                    # futurist is not available
-                    raise ImportError(
-                        ("Python 3.7+ and Eventlet cause the `concurrent.futures.ThreadPoolExecutor` "
-                         "to 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 https://github.com/eventlet/eventlet/issues/508 "
-                         "for more details."))
-
-        return tpe_class(**kwargs)
+        return ThreadPoolExecutor(**kwargs)
 
     def register_user_type(self, keyspace, user_type, klass):
         """

pyproject.toml

@@ -45,9 +45,7 @@ dev = [
     "pytest~=8.0",
     "PyYAML",
     "pure-sasl",
-    "twisted[tls]",
-    "gevent",
-    "eventlet>=0.33.3",
+    "cryptography>=42.0",
     "cython>=3.2",
     "setuptools",
     "packaging>=25.0",
@@ -165,18 +163,15 @@ test-extras = ["compress-lz4"]
 # so skipping is disabled (CASS_DRIVER_NO_SKIP=1): a missing dependency such as
 # libev fails loudly instead of being silently skipped. Tests that cannot run in
 # the default configuration are listed explicitly:
-#   * event-loop reactor tests are run separately with the matching
-#     EVENT_LOOP_MANAGER (gevent/eventlet/asyncio);
+#   * the asyncio reactor test is run separately with EVENT_LOOP_MANAGER=asyncio;
 #   * asyncore is deprecated and unavailable on modern Python, so it is ignored;
 #   * column_encryption is disabled upstream (scylladb/python-driver#365);
 #   * test_deserialize_date_range_month is disabled upstream (PYTHON-912).
-# PyPy uses the pp* override below. All Linux CPython reactor commands run with
+# PyPy uses the pp* override below. The Linux CPython reactor command runs with
 # CASS_DRIVER_NO_SKIP=1 so unexpected skips fail loudly.
 test-command = [
-    "CASS_DRIVER_NO_SKIP=1 pytest --import-mode=append {package}/tests/unit -v --ignore={package}/tests/unit/column_encryption --ignore={package}/tests/unit/io/test_geventreactor.py --ignore={package}/tests/unit/io/test_eventletreactor.py --ignore={package}/tests/unit/io/test_asyncioreactor.py --ignore={package}/tests/unit/io/test_asyncorereactor.py -k 'not test_deserialize_date_range_month'",
-    "EVENT_LOOP_MANAGER=gevent CASS_DRIVER_NO_SKIP=1 pytest --import-mode=append {package}/tests/unit/io/test_geventreactor.py -v",
+    "CASS_DRIVER_NO_SKIP=1 pytest --import-mode=append {package}/tests/unit -v --ignore={package}/tests/unit/column_encryption --ignore={package}/tests/unit/io/test_asyncioreactor.py --ignore={package}/tests/unit/io/test_asyncorereactor.py -k 'not test_deserialize_date_range_month'",
     "EVENT_LOOP_MANAGER=asyncio CASS_DRIVER_NO_SKIP=1 pytest --import-mode=append {package}/tests/unit/io/test_asyncioreactor.py -v",
-    "EVENT_LOOP_MANAGER=eventlet CASS_DRIVER_NO_SKIP=1 pytest --import-mode=append {package}/tests/unit/io/test_eventletreactor.py -v",
 ]
 
 [tool.cibuildwheel.macos]
@@ -185,10 +180,10 @@ build-frontend = "build"
 test-extras = ["compress-lz4"]
 # Same policy as Linux (extensions are mandatory here too, libev comes from
 # Homebrew). The extra -k exclusions are timing-sensitive tests that are flaky
-# on macOS runners. The gevent/eventlet/asyncio reactor test files only contain
-# those timing-sensitive timer tests, so they are not run separately here.
+# on macOS runners. The asyncio reactor test file only contains those
+# timing-sensitive timer tests, so it is not run separately here.
 test-command = [
-    "CASS_DRIVER_NO_SKIP=1 pytest --import-mode=append {project}/tests/unit -v --ignore={project}/tests/unit/column_encryption --ignore={project}/tests/unit/io/test_geventreactor.py --ignore={project}/tests/unit/io/test_eventletreactor.py --ignore={project}/tests/unit/io/test_asyncioreactor.py --ignore={project}/tests/unit/io/test_asyncorereactor.py -k 'not (test_multi_timer_validation or test_empty_connections or test_timer_cancellation or test_deserialize_date_range_month)'",
+    "CASS_DRIVER_NO_SKIP=1 pytest --import-mode=append {project}/tests/unit -v --ignore={project}/tests/unit/column_encryption --ignore={project}/tests/unit/io/test_asyncioreactor.py --ignore={project}/tests/unit/io/test_asyncorereactor.py -k 'not (test_multi_timer_validation or test_empty_connections or test_timer_cancellation or test_deserialize_date_range_month)'",
 ]
 
 [tool.cibuildwheel.windows]