FEAT: Python support for Pooling

[gargsaumya]

This pull request introduces connection pooling functionality to the mssql_python library. The changes include adding a new module to manage pooling configuration, modifying existing connection logic to support pooling, and extending the C++ bindings to handle the new pooling parameter.

Connection pooling feature:

• mssql_python/pool_config.py: Added a new module to manage connection pooling, including a global _pooling_enabled flag and an enable_pooling function to configure pooling parameters.

Integration of pooling into Python connection logic:

• mssql_python/connection.py: Updated the Connection class to include the _pooling_enabled flag when creating a connection, ensuring pooling is respected in subsequent operations.
• mssql_python/__init__.py: Imported the enable_pooling function from the new pool_config module to make it accessible at the package level.

Extension of C++ bindings for pooling:

• mssql_python/pybind/connection/connection.cpp and connection.h: Modified the Connection constructor to accept a new use_pooling parameter and store it as _usePool. [1] [2]
• mssql_python/pybind/ddbc_bindings.cpp: Updated the Pybind11 bindings for the Connection class to include the use_pooling parameter, allowing Python code to pass pooling configuration to the underlying C++ implementation.

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Checklist

• Tests Passed (if applicable) : All pytests are passing

[Copilot]

Pull Request Overview

This PR refactors the mssql_python driver to use a unified C++ ddbc_bindings.Connection class for all connection operations, removes legacy handle‐management code, and adds a placeholder API for connection pooling.

• Swap out manual ODBC handle setup/teardown for ddbc_bindings.Connection
• Introduce pool_config.enable_pooling and pass pooling flag into new C++ Connection
• Update cursor to call into Connection.alloc_statement_handle and clean up redundant logic

Reviewed Changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
tests/test_005_exceptions.py	Updated expected exception type/message for invalid connection
mssql_python/pybind/ddbc_bindings.h	Added includes, mutex, ErrorInfo struct, and once_flag
mssql_python/pybind/ddbc_bindings.cpp	Removed old wrap functions, adjusted SqlHandle destructor, bound new Connection API
mssql_python/pybind/connection/connection.h	Introduced new C++ Connection class signature and members
mssql_python/pybind/connection/connection.cpp	Fully implemented Connection logic, error handling, and pooling flag
mssql_python/pool_config.py	New module with enable_pooling stub
mssql_python/cursor.py	Use Connection.alloc_statement_handle() and tidy free logic
mssql_python/connection.py	Swap to using C++ Connection, remove legacy handle methods
mssql_python/init.py	Exported enable_pooling

Comments suppressed due to low confidence (1)

mssql_python/pybind/ddbc_bindings.h:15

• [nitpick] m_driverLoaded is never initialized or used after switching to std::call_once. Remove it or initialize/use it consistently to avoid confusion.

bool m_driverLoaded;

[sumitmsft]

I have added a few comments to keep a note of. Please see if you can incorporate them when you make changes to ddbc_bindings.cpp.

[bewithgaurav]

Approved with some minor suggestions for refactoring, can be added as a TODO for later use.