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from typing import Any

from .base import Connection

try:
    import queue
except ImportError:
    import Queue as queue  # type: ignore


class PoolingConnection(Connection):
    _free_connections: queue.Queue[Connection]

    """
    Base connection class for connections that use libraries without thread
    safety and no capacity for connection pooling. To use this just implement a
    ``_make_connection`` method that constructs a new connection and returns
    it.
    """

    def __init__(self, *args: Any, **kwargs: Any) -> None:
        self._free_connections = queue.Queue()
        super(PoolingConnection, self).__init__(*args, **kwargs)

    def _make_connection(self) -> Connection:
        raise NotImplementedError

    def _get_connection(self) -> Connection:
        try:
            return self._free_connections.get_nowait()
        except queue.Empty:
            return self._make_connection()

    def _release_connection(self, con: Connection) -> None:
        self._free_connections.put(con)

    def close(self) -> None:
        """
        Explicitly close connection
        """
        pass