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https://github.com/janeczku/calibre-web
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1080 lines
36 KiB
Python
1080 lines
36 KiB
Python
# sqlalchemy/pool.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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"""Connection pooling for DB-API connections.
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Provides a number of connection pool implementations for a variety of
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usage scenarios and thread behavior requirements imposed by the
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application, DB-API or database itself.
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Also provides a DB-API 2.0 connection proxying mechanism allowing
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regular DB-API connect() methods to be transparently managed by a
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SQLAlchemy connection pool.
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"""
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import time
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import traceback
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import weakref
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from . import exc, log, event, events, interfaces, util
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from .util import queue as sqla_queue
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from .util import threading, memoized_property, \
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chop_traceback
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proxies = {}
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def manage(module, **params):
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"""Return a proxy for a DB-API module that automatically
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pools connections.
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Given a DB-API 2.0 module and pool management parameters, returns
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a proxy for the module that will automatically pool connections,
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creating new connection pools for each distinct set of connection
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arguments sent to the decorated module's connect() function.
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:param module: a DB-API 2.0 database module
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:param poolclass: the class used by the pool module to provide
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pooling. Defaults to :class:`.QueuePool`.
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:param \*\*params: will be passed through to *poolclass*
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"""
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try:
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return proxies[module]
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except KeyError:
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return proxies.setdefault(module, _DBProxy(module, **params))
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def clear_managers():
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"""Remove all current DB-API 2.0 managers.
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All pools and connections are disposed.
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"""
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for manager in proxies.itervalues():
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manager.close()
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proxies.clear()
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reset_rollback = util.symbol('reset_rollback')
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reset_commit = util.symbol('reset_commit')
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reset_none = util.symbol('reset_none')
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class _ConnDialect(object):
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"""partial implementation of :class:`.Dialect`
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which provides DBAPI connection methods.
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When a :class:`.Pool` is combined with an :class:`.Engine`,
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the :class:`.Engine` replaces this with its own
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:class:`.Dialect`.
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"""
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def do_rollback(self, dbapi_connection):
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dbapi_connection.rollback()
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def do_commit(self, dbapi_connection):
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dbapi_connection.commit()
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def do_close(self, dbapi_connection):
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dbapi_connection.close()
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class Pool(log.Identified):
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"""Abstract base class for connection pools."""
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_dialect = _ConnDialect()
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def __init__(self,
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creator, recycle=-1, echo=None,
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use_threadlocal=False,
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logging_name=None,
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reset_on_return=True,
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listeners=None,
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events=None,
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_dispatch=None,
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_dialect=None):
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"""
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Construct a Pool.
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:param creator: a callable function that returns a DB-API
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connection object. The function will be called with
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parameters.
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:param recycle: If set to non -1, number of seconds between
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connection recycling, which means upon checkout, if this
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timeout is surpassed the connection will be closed and
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replaced with a newly opened connection. Defaults to -1.
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:param logging_name: String identifier which will be used within
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the "name" field of logging records generated within the
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"sqlalchemy.pool" logger. Defaults to a hexstring of the object's
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id.
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:param echo: If True, connections being pulled and retrieved
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from the pool will be logged to the standard output, as well
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as pool sizing information. Echoing can also be achieved by
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enabling logging for the "sqlalchemy.pool"
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namespace. Defaults to False.
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:param use_threadlocal: If set to True, repeated calls to
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:meth:`connect` within the same application thread will be
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guaranteed to return the same connection object, if one has
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already been retrieved from the pool and has not been
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returned yet. Offers a slight performance advantage at the
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cost of individual transactions by default. The
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:meth:`unique_connection` method is provided to bypass the
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threadlocal behavior installed into :meth:`connect`.
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:param reset_on_return: Configures the action to take
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on connections as they are returned to the pool.
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See the argument description in :class:`.QueuePool` for
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more detail.
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:param events: a list of 2-tuples, each of the form
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``(callable, target)`` which will be passed to event.listen()
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upon construction. Provided here so that event listeners
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can be assigned via ``create_engine`` before dialect-level
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listeners are applied.
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:param listeners: Deprecated. A list of
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:class:`~sqlalchemy.interfaces.PoolListener`-like objects or
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dictionaries of callables that receive events when DB-API
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connections are created, checked out and checked in to the
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pool. This has been superseded by
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:func:`~sqlalchemy.event.listen`.
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"""
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if logging_name:
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self.logging_name = self._orig_logging_name = logging_name
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else:
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self._orig_logging_name = None
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log.instance_logger(self, echoflag=echo)
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self._threadconns = threading.local()
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self._creator = creator
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self._recycle = recycle
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self._use_threadlocal = use_threadlocal
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if reset_on_return in ('rollback', True, reset_rollback):
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self._reset_on_return = reset_rollback
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elif reset_on_return in (None, False, reset_none):
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self._reset_on_return = reset_none
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elif reset_on_return in ('commit', reset_commit):
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self._reset_on_return = reset_commit
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else:
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raise exc.ArgumentError(
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"Invalid value for 'reset_on_return': %r"
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% reset_on_return)
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self.echo = echo
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if _dispatch:
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self.dispatch._update(_dispatch, only_propagate=False)
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if _dialect:
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self._dialect = _dialect
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if events:
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for fn, target in events:
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event.listen(self, target, fn)
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if listeners:
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util.warn_deprecated(
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"The 'listeners' argument to Pool (and "
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"create_engine()) is deprecated. Use event.listen().")
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for l in listeners:
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self.add_listener(l)
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dispatch = event.dispatcher(events.PoolEvents)
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def _close_connection(self, connection):
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self.logger.debug("Closing connection %r", connection)
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try:
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self._dialect.do_close(connection)
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except (SystemExit, KeyboardInterrupt):
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raise
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except:
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self.logger.debug("Exception closing connection %r",
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connection)
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@util.deprecated(
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2.7, "Pool.add_listener is deprecated. Use event.listen()")
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def add_listener(self, listener):
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"""Add a :class:`.PoolListener`-like object to this pool.
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``listener`` may be an object that implements some or all of
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PoolListener, or a dictionary of callables containing implementations
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of some or all of the named methods in PoolListener.
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"""
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interfaces.PoolListener._adapt_listener(self, listener)
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def unique_connection(self):
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"""Produce a DBAPI connection that is not referenced by any
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thread-local context.
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This method is different from :meth:`.Pool.connect` only if the
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``use_threadlocal`` flag has been set to ``True``.
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"""
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return _ConnectionFairy(self).checkout()
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def _create_connection(self):
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"""Called by subclasses to create a new ConnectionRecord."""
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return _ConnectionRecord(self)
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def recreate(self):
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"""Return a new :class:`.Pool`, of the same class as this one
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and configured with identical creation arguments.
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This method is used in conjunection with :meth:`dispose`
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to close out an entire :class:`.Pool` and create a new one in
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its place.
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"""
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raise NotImplementedError()
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def dispose(self):
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"""Dispose of this pool.
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This method leaves the possibility of checked-out connections
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remaining open, as it only affects connections that are
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idle in the pool.
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See also the :meth:`Pool.recreate` method.
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"""
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raise NotImplementedError()
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def _replace(self):
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"""Dispose + recreate this pool.
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Subclasses may employ special logic to
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move threads waiting on this pool to the
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new one.
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"""
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self.dispose()
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return self.recreate()
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def connect(self):
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"""Return a DBAPI connection from the pool.
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The connection is instrumented such that when its
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``close()`` method is called, the connection will be returned to
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the pool.
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"""
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if not self._use_threadlocal:
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return _ConnectionFairy(self).checkout()
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try:
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rec = self._threadconns.current()
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if rec:
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return rec.checkout()
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except AttributeError:
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pass
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agent = _ConnectionFairy(self)
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self._threadconns.current = weakref.ref(agent)
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return agent.checkout()
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def _return_conn(self, record):
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"""Given a _ConnectionRecord, return it to the :class:`.Pool`.
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This method is called when an instrumented DBAPI connection
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has its ``close()`` method called.
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"""
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if self._use_threadlocal:
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try:
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del self._threadconns.current
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except AttributeError:
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pass
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self._do_return_conn(record)
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def _do_get(self):
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"""Implementation for :meth:`get`, supplied by subclasses."""
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raise NotImplementedError()
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def _do_return_conn(self, conn):
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"""Implementation for :meth:`return_conn`, supplied by subclasses."""
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raise NotImplementedError()
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def status(self):
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raise NotImplementedError()
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class _ConnectionRecord(object):
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finalize_callback = None
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def __init__(self, pool):
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self.__pool = pool
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self.connection = self.__connect()
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pool.dispatch.first_connect.\
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for_modify(pool.dispatch).\
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exec_once(self.connection, self)
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pool.dispatch.connect(self.connection, self)
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@util.memoized_property
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def info(self):
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return {}
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def close(self):
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if self.connection is not None:
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self.__pool._close_connection(self.connection)
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def invalidate(self, e=None):
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if e is not None:
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self.__pool.logger.info(
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"Invalidate connection %r (reason: %s:%s)",
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self.connection, e.__class__.__name__, e)
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else:
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self.__pool.logger.info(
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"Invalidate connection %r", self.connection)
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self.__close()
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self.connection = None
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def get_connection(self):
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if self.connection is None:
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self.connection = self.__connect()
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self.info.clear()
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if self.__pool.dispatch.connect:
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self.__pool.dispatch.connect(self.connection, self)
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elif self.__pool._recycle > -1 and \
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time.time() - self.starttime > self.__pool._recycle:
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self.__pool.logger.info(
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"Connection %r exceeded timeout; recycling",
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self.connection)
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self.__close()
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self.connection = self.__connect()
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self.info.clear()
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if self.__pool.dispatch.connect:
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self.__pool.dispatch.connect(self.connection, self)
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return self.connection
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def checkin(self):
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self.fairy = None
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connection = self.connection
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pool = self.__pool
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if self.finalize_callback:
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self.finalize_callback(connection)
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del self.finalize_callback
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if pool.dispatch.checkin:
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pool.dispatch.checkin(connection, self)
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pool._return_conn(self)
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def __close(self):
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self.__pool._close_connection(self.connection)
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def __connect(self):
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try:
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self.starttime = time.time()
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connection = self.__pool._creator()
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self.__pool.logger.debug("Created new connection %r", connection)
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return connection
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except Exception, e:
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self.__pool.logger.debug("Error on connect(): %s", e)
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raise
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def _finalize_fairy(connection, connection_record, pool, ref, echo):
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_refs.discard(connection_record)
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if ref is not None and \
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connection_record.fairy is not ref:
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return
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if connection_record and echo:
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pool.logger.debug("Connection %r being returned to pool",
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connection)
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if connection is not None:
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try:
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if pool.dispatch.reset:
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pool.dispatch.reset(connection, connection_record)
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if pool._reset_on_return is reset_rollback:
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pool._dialect.do_rollback(connection)
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elif pool._reset_on_return is reset_commit:
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pool._dialect.do_commit(connection)
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# Immediately close detached instances
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if connection_record is None:
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pool._close_connection(connection)
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except Exception, e:
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if connection_record is not None:
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connection_record.invalidate(e=e)
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if isinstance(e, (SystemExit, KeyboardInterrupt)):
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raise
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if connection_record:
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connection_record.checkin()
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_refs = set()
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class _ConnectionFairy(object):
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"""Proxies a DB-API connection and provides return-on-dereference
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support."""
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def __init__(self, pool):
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self._pool = pool
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self.__counter = 0
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self._echo = _echo = pool._should_log_debug()
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try:
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rec = self._connection_record = pool._do_get()
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try:
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conn = self.connection = self._connection_record.get_connection()
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except:
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self._connection_record.checkin()
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raise
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rec.fairy = weakref.ref(
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self,
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lambda ref: _finalize_fairy and \
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_finalize_fairy(conn, rec, pool, ref, _echo)
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)
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_refs.add(rec)
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except:
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# helps with endless __getattr__ loops later on
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self.connection = None
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self._connection_record = None
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raise
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if self._echo:
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self._pool.logger.debug("Connection %r checked out from pool" %
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self.connection)
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@property
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def _logger(self):
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return self._pool.logger
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@property
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def is_valid(self):
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return self.connection is not None
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@util.memoized_property
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def info(self):
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"""Info dictionary associated with the underlying DBAPI connection
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referred to by this :class:`.ConnectionFairy`, allowing user-defined
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data to be associated with the connection.
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The data here will follow along with the DBAPI connection including
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after it is returned to the connection pool and used again
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in subsequent instances of :class:`.ConnectionFairy`.
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"""
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try:
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return self._connection_record.info
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except AttributeError:
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raise exc.InvalidRequestError("This connection is closed")
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def invalidate(self, e=None):
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"""Mark this connection as invalidated.
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The connection will be immediately closed. The containing
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ConnectionRecord will create a new connection when next used.
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"""
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if self.connection is None:
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raise exc.InvalidRequestError("This connection is closed")
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if self._connection_record is not None:
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self._connection_record.invalidate(e=e)
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self.connection = None
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self._close()
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def cursor(self, *args, **kwargs):
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return self.connection.cursor(*args, **kwargs)
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def __getattr__(self, key):
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return getattr(self.connection, key)
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def checkout(self):
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if self.connection is None:
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raise exc.InvalidRequestError("This connection is closed")
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self.__counter += 1
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if not self._pool.dispatch.checkout or self.__counter != 1:
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return self
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# Pool listeners can trigger a reconnection on checkout
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attempts = 2
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while attempts > 0:
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try:
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self._pool.dispatch.checkout(self.connection,
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self._connection_record,
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self)
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return self
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except exc.DisconnectionError, e:
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self._pool.logger.info(
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"Disconnection detected on checkout: %s", e)
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self._connection_record.invalidate(e)
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self.connection = self._connection_record.get_connection()
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attempts -= 1
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self._pool.logger.info("Reconnection attempts exhausted on checkout")
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self.invalidate()
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raise exc.InvalidRequestError("This connection is closed")
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def detach(self):
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"""Separate this connection from its Pool.
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This means that the connection will no longer be returned to the
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pool when closed, and will instead be literally closed. The
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containing ConnectionRecord is separated from the DB-API connection,
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and will create a new connection when next used.
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Note that any overall connection limiting constraints imposed by a
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Pool implementation may be violated after a detach, as the detached
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connection is removed from the pool's knowledge and control.
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"""
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if self._connection_record is not None:
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_refs.remove(self._connection_record)
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self._connection_record.fairy = None
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self._connection_record.connection = None
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self._pool._do_return_conn(self._connection_record)
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self.info = self.info.copy()
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self._connection_record = None
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def close(self):
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self.__counter -= 1
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if self.__counter == 0:
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self._close()
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def _close(self):
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_finalize_fairy(self.connection, self._connection_record,
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self._pool, None, self._echo)
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self.connection = None
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self._connection_record = None
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class SingletonThreadPool(Pool):
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"""A Pool that maintains one connection per thread.
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Maintains one connection per each thread, never moving a connection to a
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thread other than the one which it was created in.
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Options are the same as those of :class:`.Pool`, as well as:
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:param pool_size: The number of threads in which to maintain connections
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at once. Defaults to five.
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:class:`.SingletonThreadPool` is used by the SQLite dialect
|
|
automatically when a memory-based database is used.
|
|
See :ref:`sqlite_toplevel`.
|
|
|
|
"""
|
|
|
|
def __init__(self, creator, pool_size=5, **kw):
|
|
kw['use_threadlocal'] = True
|
|
Pool.__init__(self, creator, **kw)
|
|
self._conn = threading.local()
|
|
self._all_conns = set()
|
|
self.size = pool_size
|
|
|
|
def recreate(self):
|
|
self.logger.info("Pool recreating")
|
|
return self.__class__(self._creator,
|
|
pool_size=self.size,
|
|
recycle=self._recycle,
|
|
echo=self.echo,
|
|
logging_name=self._orig_logging_name,
|
|
use_threadlocal=self._use_threadlocal,
|
|
reset_on_return=self._reset_on_return,
|
|
_dispatch=self.dispatch,
|
|
_dialect=self._dialect)
|
|
|
|
def dispose(self):
|
|
"""Dispose of this pool."""
|
|
|
|
for conn in self._all_conns:
|
|
try:
|
|
conn.close()
|
|
except (SystemExit, KeyboardInterrupt):
|
|
raise
|
|
except:
|
|
# pysqlite won't even let you close a conn from a thread
|
|
# that didn't create it
|
|
pass
|
|
|
|
self._all_conns.clear()
|
|
|
|
def _cleanup(self):
|
|
while len(self._all_conns) > self.size:
|
|
c = self._all_conns.pop()
|
|
c.close()
|
|
|
|
def status(self):
|
|
return "SingletonThreadPool id:%d size: %d" % \
|
|
(id(self), len(self._all_conns))
|
|
|
|
def _do_return_conn(self, conn):
|
|
pass
|
|
|
|
def _do_get(self):
|
|
try:
|
|
c = self._conn.current()
|
|
if c:
|
|
return c
|
|
except AttributeError:
|
|
pass
|
|
c = self._create_connection()
|
|
self._conn.current = weakref.ref(c)
|
|
self._all_conns.add(c)
|
|
if len(self._all_conns) > self.size:
|
|
self._cleanup()
|
|
return c
|
|
|
|
|
|
class DummyLock(object):
|
|
|
|
def acquire(self, wait=True):
|
|
return True
|
|
|
|
def release(self):
|
|
pass
|
|
|
|
|
|
class QueuePool(Pool):
|
|
"""A :class:`.Pool` that imposes a limit on the number of open connections.
|
|
|
|
:class:`.QueuePool` is the default pooling implementation used for
|
|
all :class:`.Engine` objects, unless the SQLite dialect is in use.
|
|
|
|
"""
|
|
|
|
def __init__(self, creator, pool_size=5, max_overflow=10, timeout=30,
|
|
**kw):
|
|
"""
|
|
Construct a QueuePool.
|
|
|
|
:param creator: a callable function that returns a DB-API
|
|
connection object. The function will be called with
|
|
parameters.
|
|
|
|
:param pool_size: The size of the pool to be maintained,
|
|
defaults to 5. This is the largest number of connections that
|
|
will be kept persistently in the pool. Note that the pool
|
|
begins with no connections; once this number of connections
|
|
is requested, that number of connections will remain.
|
|
``pool_size`` can be set to 0 to indicate no size limit; to
|
|
disable pooling, use a :class:`~sqlalchemy.pool.NullPool`
|
|
instead.
|
|
|
|
:param max_overflow: The maximum overflow size of the
|
|
pool. When the number of checked-out connections reaches the
|
|
size set in pool_size, additional connections will be
|
|
returned up to this limit. When those additional connections
|
|
are returned to the pool, they are disconnected and
|
|
discarded. It follows then that the total number of
|
|
simultaneous connections the pool will allow is pool_size +
|
|
`max_overflow`, and the total number of "sleeping"
|
|
connections the pool will allow is pool_size. `max_overflow`
|
|
can be set to -1 to indicate no overflow limit; no limit
|
|
will be placed on the total number of concurrent
|
|
connections. Defaults to 10.
|
|
|
|
:param timeout: The number of seconds to wait before giving up
|
|
on returning a connection. Defaults to 30.
|
|
|
|
:param recycle: If set to non -1, number of seconds between
|
|
connection recycling, which means upon checkout, if this
|
|
timeout is surpassed the connection will be closed and
|
|
replaced with a newly opened connection. Defaults to -1.
|
|
|
|
:param echo: If True, connections being pulled and retrieved
|
|
from the pool will be logged to the standard output, as well
|
|
as pool sizing information. Echoing can also be achieved by
|
|
enabling logging for the "sqlalchemy.pool"
|
|
namespace. Defaults to False.
|
|
|
|
:param use_threadlocal: If set to True, repeated calls to
|
|
:meth:`connect` within the same application thread will be
|
|
guaranteed to return the same connection object, if one has
|
|
already been retrieved from the pool and has not been
|
|
returned yet. Offers a slight performance advantage at the
|
|
cost of individual transactions by default. The
|
|
:meth:`unique_connection` method is provided to bypass the
|
|
threadlocal behavior installed into :meth:`connect`.
|
|
|
|
:param reset_on_return: Determine steps to take on
|
|
connections as they are returned to the pool.
|
|
reset_on_return can have any of these values:
|
|
|
|
* 'rollback' - call rollback() on the connection,
|
|
to release locks and transaction resources.
|
|
This is the default value. The vast majority
|
|
of use cases should leave this value set.
|
|
* True - same as 'rollback', this is here for
|
|
backwards compatibility.
|
|
* 'commit' - call commit() on the connection,
|
|
to release locks and transaction resources.
|
|
A commit here may be desirable for databases that
|
|
cache query plans if a commit is emitted,
|
|
such as Microsoft SQL Server. However, this
|
|
value is more dangerous than 'rollback' because
|
|
any data changes present on the transaction
|
|
are committed unconditionally.
|
|
* None - don't do anything on the connection.
|
|
This setting should only be made on a database
|
|
that has no transaction support at all,
|
|
namely MySQL MyISAM. By not doing anything,
|
|
performance can be improved. This
|
|
setting should **never be selected** for a
|
|
database that supports transactions,
|
|
as it will lead to deadlocks and stale
|
|
state.
|
|
* False - same as None, this is here for
|
|
backwards compatibility.
|
|
|
|
.. versionchanged:: 0.7.6
|
|
``reset_on_return`` accepts values.
|
|
|
|
:param listeners: A list of
|
|
:class:`~sqlalchemy.interfaces.PoolListener`-like objects or
|
|
dictionaries of callables that receive events when DB-API
|
|
connections are created, checked out and checked in to the
|
|
pool.
|
|
|
|
"""
|
|
Pool.__init__(self, creator, **kw)
|
|
self._pool = sqla_queue.Queue(pool_size)
|
|
self._overflow = 0 - pool_size
|
|
self._max_overflow = max_overflow
|
|
self._timeout = timeout
|
|
self._overflow_lock = threading.Lock() if self._max_overflow > -1 \
|
|
else DummyLock()
|
|
|
|
def _do_return_conn(self, conn):
|
|
try:
|
|
self._pool.put(conn, False)
|
|
except sqla_queue.Full:
|
|
conn.close()
|
|
self._overflow_lock.acquire()
|
|
try:
|
|
self._overflow -= 1
|
|
finally:
|
|
self._overflow_lock.release()
|
|
|
|
def _do_get(self):
|
|
try:
|
|
wait = self._max_overflow > -1 and \
|
|
self._overflow >= self._max_overflow
|
|
return self._pool.get(wait, self._timeout)
|
|
except sqla_queue.SAAbort, aborted:
|
|
return aborted.context._do_get()
|
|
except sqla_queue.Empty:
|
|
if self._max_overflow > -1 and \
|
|
self._overflow >= self._max_overflow:
|
|
if not wait:
|
|
return self._do_get()
|
|
else:
|
|
raise exc.TimeoutError(
|
|
"QueuePool limit of size %d overflow %d reached, "
|
|
"connection timed out, timeout %d" %
|
|
(self.size(), self.overflow(), self._timeout))
|
|
|
|
self._overflow_lock.acquire()
|
|
try:
|
|
if self._max_overflow > -1 and \
|
|
self._overflow >= self._max_overflow:
|
|
return self._do_get()
|
|
else:
|
|
con = self._create_connection()
|
|
self._overflow += 1
|
|
return con
|
|
finally:
|
|
self._overflow_lock.release()
|
|
|
|
def recreate(self):
|
|
self.logger.info("Pool recreating")
|
|
return self.__class__(self._creator, pool_size=self._pool.maxsize,
|
|
max_overflow=self._max_overflow,
|
|
timeout=self._timeout,
|
|
recycle=self._recycle, echo=self.echo,
|
|
logging_name=self._orig_logging_name,
|
|
use_threadlocal=self._use_threadlocal,
|
|
reset_on_return=self._reset_on_return,
|
|
_dispatch=self.dispatch,
|
|
_dialect=self._dialect)
|
|
|
|
def dispose(self):
|
|
while True:
|
|
try:
|
|
conn = self._pool.get(False)
|
|
conn.close()
|
|
except sqla_queue.Empty:
|
|
break
|
|
|
|
self._overflow = 0 - self.size()
|
|
self.logger.info("Pool disposed. %s", self.status())
|
|
|
|
def _replace(self):
|
|
self.dispose()
|
|
np = self.recreate()
|
|
self._pool.abort(np)
|
|
return np
|
|
|
|
def status(self):
|
|
return "Pool size: %d Connections in pool: %d "\
|
|
"Current Overflow: %d Current Checked out "\
|
|
"connections: %d" % (self.size(),
|
|
self.checkedin(),
|
|
self.overflow(),
|
|
self.checkedout())
|
|
|
|
def size(self):
|
|
return self._pool.maxsize
|
|
|
|
def checkedin(self):
|
|
return self._pool.qsize()
|
|
|
|
def overflow(self):
|
|
return self._overflow
|
|
|
|
def checkedout(self):
|
|
return self._pool.maxsize - self._pool.qsize() + self._overflow
|
|
|
|
|
|
class NullPool(Pool):
|
|
"""A Pool which does not pool connections.
|
|
|
|
Instead it literally opens and closes the underlying DB-API connection
|
|
per each connection open/close.
|
|
|
|
Reconnect-related functions such as ``recycle`` and connection
|
|
invalidation are not supported by this Pool implementation, since
|
|
no connections are held persistently.
|
|
|
|
.. versionchanged:: 0.7
|
|
:class:`.NullPool` is used by the SQlite dialect automatically
|
|
when a file-based database is used. See :ref:`sqlite_toplevel`.
|
|
|
|
"""
|
|
|
|
def status(self):
|
|
return "NullPool"
|
|
|
|
def _do_return_conn(self, conn):
|
|
conn.close()
|
|
|
|
def _do_get(self):
|
|
return self._create_connection()
|
|
|
|
def recreate(self):
|
|
self.logger.info("Pool recreating")
|
|
|
|
return self.__class__(self._creator,
|
|
recycle=self._recycle,
|
|
echo=self.echo,
|
|
logging_name=self._orig_logging_name,
|
|
use_threadlocal=self._use_threadlocal,
|
|
reset_on_return=self._reset_on_return,
|
|
_dispatch=self.dispatch,
|
|
_dialect=self._dialect)
|
|
|
|
def dispose(self):
|
|
pass
|
|
|
|
|
|
class StaticPool(Pool):
|
|
"""A Pool of exactly one connection, used for all requests.
|
|
|
|
Reconnect-related functions such as ``recycle`` and connection
|
|
invalidation (which is also used to support auto-reconnect) are not
|
|
currently supported by this Pool implementation but may be implemented
|
|
in a future release.
|
|
|
|
"""
|
|
|
|
@memoized_property
|
|
def _conn(self):
|
|
return self._creator()
|
|
|
|
@memoized_property
|
|
def connection(self):
|
|
return _ConnectionRecord(self)
|
|
|
|
def status(self):
|
|
return "StaticPool"
|
|
|
|
def dispose(self):
|
|
if '_conn' in self.__dict__:
|
|
self._conn.close()
|
|
self._conn = None
|
|
|
|
def recreate(self):
|
|
self.logger.info("Pool recreating")
|
|
return self.__class__(creator=self._creator,
|
|
recycle=self._recycle,
|
|
use_threadlocal=self._use_threadlocal,
|
|
reset_on_return=self._reset_on_return,
|
|
echo=self.echo,
|
|
logging_name=self._orig_logging_name,
|
|
_dispatch=self.dispatch,
|
|
_dialect=self._dialect)
|
|
|
|
def _create_connection(self):
|
|
return self._conn
|
|
|
|
def _do_return_conn(self, conn):
|
|
pass
|
|
|
|
def _do_get(self):
|
|
return self.connection
|
|
|
|
|
|
class AssertionPool(Pool):
|
|
"""A :class:`.Pool` that allows at most one checked out connection at
|
|
any given time.
|
|
|
|
This will raise an exception if more than one connection is checked out
|
|
at a time. Useful for debugging code that is using more connections
|
|
than desired.
|
|
|
|
.. versionchanged:: 0.7
|
|
:class:`.AssertionPool` also logs a traceback of where
|
|
the original connection was checked out, and reports
|
|
this in the assertion error raised.
|
|
|
|
"""
|
|
def __init__(self, *args, **kw):
|
|
self._conn = None
|
|
self._checked_out = False
|
|
self._store_traceback = kw.pop('store_traceback', True)
|
|
self._checkout_traceback = None
|
|
Pool.__init__(self, *args, **kw)
|
|
|
|
def status(self):
|
|
return "AssertionPool"
|
|
|
|
def _do_return_conn(self, conn):
|
|
if not self._checked_out:
|
|
raise AssertionError("connection is not checked out")
|
|
self._checked_out = False
|
|
assert conn is self._conn
|
|
|
|
def dispose(self):
|
|
self._checked_out = False
|
|
if self._conn:
|
|
self._conn.close()
|
|
|
|
def recreate(self):
|
|
self.logger.info("Pool recreating")
|
|
return self.__class__(self._creator, echo=self.echo,
|
|
logging_name=self._orig_logging_name,
|
|
_dispatch=self.dispatch,
|
|
_dialect=self._dialect)
|
|
|
|
def _do_get(self):
|
|
if self._checked_out:
|
|
if self._checkout_traceback:
|
|
suffix = ' at:\n%s' % ''.join(
|
|
chop_traceback(self._checkout_traceback))
|
|
else:
|
|
suffix = ''
|
|
raise AssertionError("connection is already checked out" + suffix)
|
|
|
|
if not self._conn:
|
|
self._conn = self._create_connection()
|
|
|
|
self._checked_out = True
|
|
if self._store_traceback:
|
|
self._checkout_traceback = traceback.format_stack()
|
|
return self._conn
|
|
|
|
|
|
class _DBProxy(object):
|
|
"""Layers connection pooling behavior on top of a standard DB-API module.
|
|
|
|
Proxies a DB-API 2.0 connect() call to a connection pool keyed to the
|
|
specific connect parameters. Other functions and attributes are delegated
|
|
to the underlying DB-API module.
|
|
"""
|
|
|
|
def __init__(self, module, poolclass=QueuePool, **kw):
|
|
"""Initializes a new proxy.
|
|
|
|
module
|
|
a DB-API 2.0 module
|
|
|
|
poolclass
|
|
a Pool class, defaulting to QueuePool
|
|
|
|
Other parameters are sent to the Pool object's constructor.
|
|
|
|
"""
|
|
|
|
self.module = module
|
|
self.kw = kw
|
|
self.poolclass = poolclass
|
|
self.pools = {}
|
|
self._create_pool_mutex = threading.Lock()
|
|
|
|
def close(self):
|
|
for key in self.pools.keys():
|
|
del self.pools[key]
|
|
|
|
def __del__(self):
|
|
self.close()
|
|
|
|
def __getattr__(self, key):
|
|
return getattr(self.module, key)
|
|
|
|
def get_pool(self, *args, **kw):
|
|
key = self._serialize(*args, **kw)
|
|
try:
|
|
return self.pools[key]
|
|
except KeyError:
|
|
self._create_pool_mutex.acquire()
|
|
try:
|
|
if key not in self.pools:
|
|
kw.pop('sa_pool_key', None)
|
|
pool = self.poolclass(lambda:
|
|
self.module.connect(*args, **kw), **self.kw)
|
|
self.pools[key] = pool
|
|
return pool
|
|
else:
|
|
return self.pools[key]
|
|
finally:
|
|
self._create_pool_mutex.release()
|
|
|
|
def connect(self, *args, **kw):
|
|
"""Activate a connection to the database.
|
|
|
|
Connect to the database using this DBProxy's module and the given
|
|
connect arguments. If the arguments match an existing pool, the
|
|
connection will be returned from the pool's current thread-local
|
|
connection instance, or if there is no thread-local connection
|
|
instance it will be checked out from the set of pooled connections.
|
|
|
|
If the pool has no available connections and allows new connections
|
|
to be created, a new database connection will be made.
|
|
|
|
"""
|
|
|
|
return self.get_pool(*args, **kw).connect()
|
|
|
|
def dispose(self, *args, **kw):
|
|
"""Dispose the pool referenced by the given connect arguments."""
|
|
|
|
key = self._serialize(*args, **kw)
|
|
try:
|
|
del self.pools[key]
|
|
except KeyError:
|
|
pass
|
|
|
|
def _serialize(self, *args, **kw):
|
|
if "sa_pool_key" in kw:
|
|
return kw['sa_pool_key']
|
|
|
|
return tuple(
|
|
list(args) +
|
|
[(k, kw[k]) for k in sorted(kw)]
|
|
)
|