PYTHON-5087 - Convert test.test_load_balancer to async

Author: NoahStapp

test/asynchronous/test_load_balancer.py

@@ -0,0 +1,244 @@
+# Copyright 2021-present MongoDB, Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Test the Load Balancer unified spec tests."""
+from __future__ import annotations
+
+import asyncio
+import gc
+import os
+import pathlib
+import sys
+import threading
+
+import pytest
+
+sys.path[0:0] = [""]
+
+from test.asynchronous import AsyncIntegrationTest, async_client_context, unittest
+from test.asynchronous.unified_format import generate_test_classes
+from test.utils import (
+    ExceptionCatchingTask,
+    ExceptionCatchingThread,
+    async_get_pool,
+    async_wait_until,
+)
+
+from pymongo.asynchronous.helpers import anext
+
+_IS_SYNC = False
+
+pytestmark = pytest.mark.load_balancer
+
+# Location of JSON test specifications.
+if _IS_SYNC:
+    _TEST_PATH = os.path.join(pathlib.Path(__file__).resolve().parent, "load_balancer")
+else:
+    _TEST_PATH = os.path.join(pathlib.Path(__file__).resolve().parent.parent, "load_balancer")
+
+# Generate unified tests.
+globals().update(generate_test_classes(_TEST_PATH, module=__name__))
+
+
+class TestLB(AsyncIntegrationTest):
+    RUN_ON_LOAD_BALANCER = True
+    RUN_ON_SERVERLESS = True
+
+    async def test_connections_are_only_returned_once(self):
+        if "PyPy" in sys.version:
+            # Tracked in PYTHON-3011
+            self.skipTest("Test is flaky on PyPy")
+        pool = await async_get_pool(self.client)
+        n_conns = len(pool.conns)
+        await self.db.test.find_one({})
+        self.assertEqual(len(pool.conns), n_conns)
+        await (await self.db.test.aggregate([{"$limit": 1}])).to_list()
+        self.assertEqual(len(pool.conns), n_conns)
+
+    @async_client_context.require_load_balancer
+    async def test_unpin_committed_transaction(self):
+        client = await self.async_rs_client()
+        pool = await async_get_pool(client)
+        coll = client[self.db.name].test
+        async with client.start_session() as session:
+            async with await session.start_transaction():
+                self.assertEqual(pool.active_sockets, 0)
+                await coll.insert_one({}, session=session)
+                self.assertEqual(pool.active_sockets, 1)  # Pinned.
+            self.assertEqual(pool.active_sockets, 1)  # Still pinned.
+        self.assertEqual(pool.active_sockets, 0)  # Unpinned.
+
+    @async_client_context.require_failCommand_fail_point
+    async def test_cursor_gc(self):
+        async def create_resource(coll):
+            cursor = coll.find({}, batch_size=3)
+            await anext(cursor)
+            return cursor
+
+        await self._test_no_gc_deadlock(create_resource)
+
+    @async_client_context.require_failCommand_fail_point
+    async def test_command_cursor_gc(self):
+        async def create_resource(coll):
+            cursor = await coll.aggregate([], batchSize=3)
+            await anext(cursor)
+            return cursor
+
+        await self._test_no_gc_deadlock(create_resource)
+
+    async def _test_no_gc_deadlock(self, create_resource):
+        client = await self.async_rs_client()
+        pool = await async_get_pool(client)
+        coll = client[self.db.name].test
+        await coll.insert_many([{} for _ in range(10)])
+        self.assertEqual(pool.active_sockets, 0)
+        # Cause the initial find attempt to fail to induce a reference cycle.
+        args = {
+            "mode": {"times": 1},
+            "data": {
+                "failCommands": ["find", "aggregate"],
+                "closeConnection": True,
+            },
+        }
+        async with self.fail_point(args):
+            resource = await create_resource(coll)
+            if async_client_context.load_balancer:
+                self.assertEqual(pool.active_sockets, 1)  # Pinned.
+
+        if _IS_SYNC:
+            thread = PoolLocker(pool)
+            thread.start()
+            self.assertTrue(thread.locked.wait(5), "timed out")
+            # Garbage collect the resource while the pool is locked to ensure we
+            # don't deadlock.
+            del resource
+            # On PyPy it can take a few rounds to collect the cursor.
+            for _ in range(3):
+                gc.collect()
+            thread.unlock.set()
+            thread.join(5)
+            self.assertFalse(thread.is_alive())
+            self.assertIsNone(thread.exc)
+
+        else:
+            task = PoolLocker(pool)
+            self.assertTrue(await asyncio.wait_for(task.locked.wait(), timeout=5), "timed out")  # type: ignore[arg-type]
+
+            # Garbage collect the resource while the pool is locked to ensure we
+            # don't deadlock.
+            del resource
+            # On PyPy it can take a few rounds to collect the cursor.
+            for _ in range(3):
+                gc.collect()
+            task.unlock.set()
+            await task.run()
+            self.assertFalse(task.is_alive())
+            self.assertIsNone(task.exc)
+
+        await async_wait_until(lambda: pool.active_sockets == 0, "return socket")
+        # Run another operation to ensure the socket still works.
+        await coll.delete_many({})
+
+    @async_client_context.require_transactions
+    async def test_session_gc(self):
+        client = await self.async_rs_client()
+        pool = await async_get_pool(client)
+        session = client.start_session()
+        await session.start_transaction()
+        await client.test_session_gc.test.find_one({}, session=session)
+        # Cleanup the transaction left open on the server unless we're
+        # testing serverless which does not support killSessions.
+        if not async_client_context.serverless:
+            self.addAsyncCleanup(self.client.admin.command, "killSessions", [session.session_id])
+        if async_client_context.load_balancer:
+            self.assertEqual(pool.active_sockets, 1)  # Pinned.
+
+        if _IS_SYNC:
+            thread = PoolLocker(pool)
+            thread.start()
+            self.assertTrue(thread.locked.wait(5), "timed out")
+            # Garbage collect the session while the pool is locked to ensure we
+            # don't deadlock.
+            del session
+            # On PyPy it can take a few rounds to collect the session.
+            for _ in range(3):
+                gc.collect()
+            thread.unlock.set()
+            thread.join(5)
+            self.assertFalse(thread.is_alive())
+            self.assertIsNone(thread.exc)
+
+        else:
+            task = PoolLocker(pool)
+            self.assertTrue(await asyncio.wait_for(task.locked.wait(), timeout=5), "timed out")  # type: ignore[arg-type]
+
+            # Garbage collect the session while the pool is locked to ensure we
+            # don't deadlock.
+            del session
+            # On PyPy it can take a few rounds to collect the cursor.
+            for _ in range(3):
+                gc.collect()
+            task.unlock.set()
+            await task.run()
+            self.assertFalse(task.is_alive())
+            self.assertIsNone(task.exc)
+
+        await async_wait_until(lambda: pool.active_sockets == 0, "return socket")
+        # Run another operation to ensure the socket still works.
+        await client[self.db.name].test.delete_many({})
+
+
+if _IS_SYNC:
+
+    class PoolLocker(ExceptionCatchingThread):
+        def __init__(self, pool):
+            super().__init__(target=self.lock_pool)
+            self.pool = pool
+            self.daemon = True
+            self.locked = threading.Event()
+            self.unlock = threading.Event()
+
+        def lock_pool(self):
+            with self.pool.lock:
+                self.locked.set()
+                # Wait for the unlock flag.
+                unlock_pool = self.unlock.wait(10)
+                if not unlock_pool:
+                    raise Exception("timed out waiting for unlock signal: deadlock?")
+
+else:
+
+    class PoolLocker(ExceptionCatchingTask):
+        def __init__(self, pool):
+            super().__init__(self.lock_pool)
+            self.pool = pool
+            self.daemon = True
+            self.locked = asyncio.Event()
+            self.unlock = asyncio.Event()
+
+        async def lock_pool(self):
+            async with self.pool.lock:
+                self.locked.set()
+                # Wait for the unlock flag.
+                try:
+                    await asyncio.wait_for(self.unlock.wait(), timeout=10)
+                except asyncio.TimeoutError:
+                    raise Exception("timed out waiting for unlock signal: deadlock?")
+
+        def is_alive(self):
+            return not self.task.done()
+
+
+if __name__ == "__main__":
+    unittest.main()