mirror of
https://github.com/janeczku/calibre-web
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135 lines
4.0 KiB
Python
135 lines
4.0 KiB
Python
# engine/threadlocal.py
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# Copyright (C) 2005-2013 the SQLAlchemy authors and contributors <see AUTHORS file>
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#
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# This module is part of SQLAlchemy and is released under
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# the MIT License: http://www.opensource.org/licenses/mit-license.php
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"""Provides a thread-local transactional wrapper around the root Engine class.
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The ``threadlocal`` module is invoked when using the
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``strategy="threadlocal"`` flag with :func:`~sqlalchemy.engine.create_engine`.
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This module is semi-private and is invoked automatically when the threadlocal
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engine strategy is used.
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"""
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from .. import util
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from . import base
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import weakref
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class TLConnection(base.Connection):
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def __init__(self, *arg, **kw):
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super(TLConnection, self).__init__(*arg, **kw)
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self.__opencount = 0
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def _increment_connect(self):
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self.__opencount += 1
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return self
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def close(self):
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if self.__opencount == 1:
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base.Connection.close(self)
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self.__opencount -= 1
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def _force_close(self):
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self.__opencount = 0
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base.Connection.close(self)
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class TLEngine(base.Engine):
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"""An Engine that includes support for thread-local managed
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transactions.
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"""
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_tl_connection_cls = TLConnection
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def __init__(self, *args, **kwargs):
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super(TLEngine, self).__init__(*args, **kwargs)
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self._connections = util.threading.local()
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def contextual_connect(self, **kw):
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if not hasattr(self._connections, 'conn'):
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connection = None
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else:
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connection = self._connections.conn()
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if connection is None or connection.closed:
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# guards against pool-level reapers, if desired.
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# or not connection.connection.is_valid:
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connection = self._tl_connection_cls(
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self, self.pool.connect(), **kw)
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self._connections.conn = weakref.ref(connection)
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return connection._increment_connect()
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def begin_twophase(self, xid=None):
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if not hasattr(self._connections, 'trans'):
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self._connections.trans = []
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self._connections.trans.append(
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self.contextual_connect().begin_twophase(xid=xid))
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return self
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def begin_nested(self):
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if not hasattr(self._connections, 'trans'):
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self._connections.trans = []
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self._connections.trans.append(
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self.contextual_connect().begin_nested())
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return self
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def begin(self):
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if not hasattr(self._connections, 'trans'):
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self._connections.trans = []
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self._connections.trans.append(self.contextual_connect().begin())
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return self
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def __enter__(self):
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return self
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def __exit__(self, type, value, traceback):
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if type is None:
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self.commit()
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else:
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self.rollback()
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def prepare(self):
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if not hasattr(self._connections, 'trans') or \
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not self._connections.trans:
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return
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self._connections.trans[-1].prepare()
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def commit(self):
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if not hasattr(self._connections, 'trans') or \
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not self._connections.trans:
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return
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trans = self._connections.trans.pop(-1)
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trans.commit()
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def rollback(self):
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if not hasattr(self._connections, 'trans') or \
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not self._connections.trans:
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return
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trans = self._connections.trans.pop(-1)
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trans.rollback()
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def dispose(self):
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self._connections = util.threading.local()
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super(TLEngine, self).dispose()
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@property
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def closed(self):
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return not hasattr(self._connections, 'conn') or \
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self._connections.conn() is None or \
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self._connections.conn().closed
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def close(self):
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if not self.closed:
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self.contextual_connect().close()
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connection = self._connections.conn()
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connection._force_close()
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del self._connections.conn
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self._connections.trans = []
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def __repr__(self):
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return 'TLEngine(%s)' % str(self.url)
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