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File Content: `threadlocal.py`

# engine/threadlocal.py
# Copyright (C) 2005-2021 the SQLAlchemy authors and contributors
# <see AUTHORS file>
#
# This module is part of SQLAlchemy and is released under
# the MIT License: http://www.opensource.org/licenses/mit-license.php

"""Provides a thread-local transactional wrapper around the root Engine class.

The ``threadlocal`` module is invoked when using the
``strategy="threadlocal"`` flag with :func:`~sqlalchemy.engine.create_engine`.
This module is semi-private and is invoked automatically when the threadlocal
engine strategy is used.
"""

import weakref

from . import base
from .. import util


class TLConnection(base.Connection):
    def __init__(self, *arg, **kw):
        super(TLConnection, self).__init__(*arg, **kw)
        self.__opencount = 0

    def _increment_connect(self):
        self.__opencount += 1
        return self

    def close(self):
        if self.__opencount == 1:
            base.Connection.close(self)
        self.__opencount -= 1

    def _force_close(self):
        self.__opencount = 0
        base.Connection.close(self)


class TLEngine(base.Engine):
    """An Engine that includes support for thread-local managed
    transactions.

    """

    _tl_connection_cls = TLConnection

    @util.deprecated(
        "1.3",
        "The 'threadlocal' engine strategy is deprecated, and will be "
        "removed in a future release.  The strategy is no longer relevant "
        "to modern usage patterns (including that of the ORM "
        ":class:`.Session` object) which make use of a "
        ":class:`_engine.Connection` "
        "object in order to invoke statements.",
    )
    def __init__(self, *args, **kwargs):
        super(TLEngine, self).__init__(*args, **kwargs)
        self._connections = util.threading.local()

    def contextual_connect(self, **kw):
        return self._contextual_connect(**kw)

    def _contextual_connect(self, **kw):
        if not hasattr(self._connections, "conn"):
            connection = None
        else:
            connection = self._connections.conn()

        if connection is None or connection.closed:
            # guards against pool-level reapers, if desired.
            # or not connection.connection.is_valid:
            connection = self._tl_connection_cls(
                self,
                self._wrap_pool_connect(self.pool.connect, connection),
                **kw
            )
            self._connections.conn = weakref.ref(connection)

        return connection._increment_connect()

    def begin_twophase(self, xid=None):
        if not hasattr(self._connections, "trans"):
            self._connections.trans = []
        self._connections.trans.append(
            self._contextual_connect().begin_twophase(xid=xid)
        )
        return self

    def begin_nested(self):
        if not hasattr(self._connections, "trans"):
            self._connections.trans = []
        self._connections.trans.append(
            self._contextual_connect().begin_nested()
        )
        return self

    def begin(self):
        if not hasattr(self._connections, "trans"):
            self._connections.trans = []
        self._connections.trans.append(self._contextual_connect().begin())
        return self

    def __enter__(self):
        return self

    def __exit__(self, type_, value, traceback):
        if type_ is None:
            self.commit()
        else:
            self.rollback()

    def prepare(self):
        if (
            not hasattr(self._connections, "trans")
            or not self._connections.trans
        ):
            return
        self._connections.trans[-1].prepare()

    def commit(self):
        if (
            not hasattr(self._connections, "trans")
            or not self._connections.trans
        ):
            return
        trans = self._connections.trans.pop(-1)
        trans.commit()

    def rollback(self):
        if (
            not hasattr(self._connections, "trans")
            or not self._connections.trans
        ):
            return
        trans = self._connections.trans.pop(-1)
        trans.rollback()

    def dispose(self):
        self._connections = util.threading.local()
        super(TLEngine, self).dispose()

    @property
    def closed(self):
        return (
            not hasattr(self._connections, "conn")
            or self._connections.conn() is None
            or self._connections.conn().closed
        )

    def close(self):
        if not self.closed:
            self._contextual_connect().close()
            connection = self._connections.conn()
            connection._force_close()
            del self._connections.conn
            self._connections.trans = []

    def __repr__(self):
        return "TLEngine(%r)" % self.url
Name	Size	Permission
__pycache__	---	0755
__init__.py	25330 bytes	0644
base.py	87152 bytes	0644
default.py	56137 bytes	0644
interfaces.py	48491 bytes	0644
reflection.py	34712 bytes	0644
result.py	54716 bytes	0644
strategies.py	9847 bytes	0644
threadlocal.py	4764 bytes	0644
url.py	9445 bytes	0644
util.py	2421 bytes	0644
File Content: threadlocal.py

File Content: `threadlocal.py`
