… resource cleanup

Code Review Comments:
- sqldata_client.py: Replaced asyncio.gather with explicit task cancellation and cleanup via asyncio.wait to prevent orphaned background streaming tasks on failure or disconnect.
- sqldata_client.py: Enhanced SqlDataClient.close() to cancel running tunnel tasks, close active gRPC channels, and close active stream writers.
- connector.py: Replaced unbounded self._sqldata_clients list with a set and automatic cleanup callback on tunnel exit to prevent memory leaks.
- connector.py: Added try/except error cleanup for fallback_sock during synchronous driver connect in SQL_DATA mode to ensure sockets are closed on exception.

…logging

Code Review Comments:
- connector.py: Added sql_data_endpoint and sql_data_stream_timeout to create_async_connector signature and forwarded to Connector constructor.
- connector.py: Updated Connector.__init__ and create_async_connector docstrings to include IPTypes.SQL_DATA, sql_data_endpoint, and sql_data_stream_timeout.
- sqldata_client.py: Moved IPTypes import to module level and replaced hardcoded port 3307 with SERVER_PROXY_PORT constant.
- client.py: Updated logging in _get_ephemeral to use standard lazy string formatting (%s).

Code Review Comments:
- Added unit tests for Connector initialization and create_async_connector with sql_data_endpoint and sql_data_stream_timeout.
- Added unit test verifying connect_async in SQL_DATA mode with enable_iam_auth=True properly normalizes user and avoids DriverMapping KeyError.
- Added unit tests for SqlDataClient initialization, port binding via connect_tunnel, close resource/task cancellation, and FallbackSocket.

…se CloudSQLConnectionError for missing CA cert

Code Review Decisions:
- sqldata_client.py: Updated fallback IP preference order to [PRIVATE, PSC, PUBLIC] to prioritize private connectivity over public IP.
- exceptions.py: Added CloudSQLConnectionError exception class.
- connection_info.py: Raised CloudSQLConnectionError instead of generic ValueError when server_ca_cert is None.
- test_instance.py: Added unit test verifying CloudSQLConnectionError on missing server_ca_cert.

…sqldata iptype

…nential backoff

…rove state encapsulation

Code Review Comments:
- sqldata_client.py: Wrapped connection initialization and task execution in a single top-level try...finally block in _handle_tunnel to ensure client_writer, gRPC channel, and close callbacks are always cleaned up even if initialization raises an exception.
- sqldata_client.py: Improved is_resource_exhausted_error to support grpc.RpcError and unwrapped exception causes.
- sqldata_client.py: Reduced wait_closed timeout on server teardown to eliminate unnecessary 2-second delays and warning logs.
- connector.py: Added helper methods (is_cooldown_active, record_exhausted, record_success, record_fallback) to SqlDataConnState.
- connector.py: Added resource_exhausted_cooldown_period documentation to Connector.__init__ docstring.
- test_connector.py: Added unit tests for SqlDataConnState helper methods and chained exception support in is_resource_exhausted_error.