313 lines
11 KiB
Python
313 lines
11 KiB
Python
|
# sqlalchemy/interfaces.py
|
||
|
|
# Copyright (C) 2007-2016 the SQLAlchemy authors and contributors
|
||
|
|
# <see AUTHORS file>
|
||
|
|
# Copyright (C) 2007 Jason Kirtland jek@discorporate.us
|
||
|
|
#
|
||
|
|
# This module is part of SQLAlchemy and is released under
|
||
|
|
# the MIT License: http://www.opensource.org/licenses/mit-license.php
|
||
|
|
|
||
|
|
"""Deprecated core event interfaces.
|
||
|
|
|
||
|
|
This module is **deprecated** and is superseded by the
|
||
|
|
event system.
|
||
|
|
|
||
|
|
"""
|
||
|
|
|
||
|
|
from . import event, util
|
||
|
|
|
||
|
|
|
||
|
|
class PoolListener(object):
|
||
|
|
"""Hooks into the lifecycle of connections in a :class:`.Pool`.
|
||
|
|
|
||
|
|
.. note::
|
||
|
|
|
||
|
|
:class:`.PoolListener` is deprecated. Please
|
||
|
|
refer to :class:`.PoolEvents`.
|
||
|
|
|
||
|
|
Usage::
|
||
|
|
|
||
|
|
class MyListener(PoolListener):
|
||
|
|
def connect(self, dbapi_con, con_record):
|
||
|
|
'''perform connect operations'''
|
||
|
|
# etc.
|
||
|
|
|
||
|
|
# create a new pool with a listener
|
||
|
|
p = QueuePool(..., listeners=[MyListener()])
|
||
|
|
|
||
|
|
# add a listener after the fact
|
||
|
|
p.add_listener(MyListener())
|
||
|
|
|
||
|
|
# usage with create_engine()
|
||
|
|
e = create_engine("url://", listeners=[MyListener()])
|
||
|
|
|
||
|
|
All of the standard connection :class:`~sqlalchemy.pool.Pool` types can
|
||
|
|
accept event listeners for key connection lifecycle events:
|
||
|
|
creation, pool check-out and check-in. There are no events fired
|
||
|
|
when a connection closes.
|
||
|
|
|
||
|
|
For any given DB-API connection, there will be one ``connect``
|
||
|
|
event, `n` number of ``checkout`` events, and either `n` or `n - 1`
|
||
|
|
``checkin`` events. (If a ``Connection`` is detached from its
|
||
|
|
pool via the ``detach()`` method, it won't be checked back in.)
|
||
|
|
|
||
|
|
These are low-level events for low-level objects: raw Python
|
||
|
|
DB-API connections, without the conveniences of the SQLAlchemy
|
||
|
|
``Connection`` wrapper, ``Dialect`` services or ``ClauseElement``
|
||
|
|
execution. If you execute SQL through the connection, explicitly
|
||
|
|
closing all cursors and other resources is recommended.
|
||
|
|
|
||
|
|
Events also receive a ``_ConnectionRecord``, a long-lived internal
|
||
|
|
``Pool`` object that basically represents a "slot" in the
|
||
|
|
connection pool. ``_ConnectionRecord`` objects have one public
|
||
|
|
attribute of note: ``info``, a dictionary whose contents are
|
||
|
|
scoped to the lifetime of the DB-API connection managed by the
|
||
|
|
record. You can use this shared storage area however you like.
|
||
|
|
|
||
|
|
There is no need to subclass ``PoolListener`` to handle events.
|
||
|
|
Any class that implements one or more of these methods can be used
|
||
|
|
as a pool listener. The ``Pool`` will inspect the methods
|
||
|
|
provided by a listener object and add the listener to one or more
|
||
|
|
internal event queues based on its capabilities. In terms of
|
||
|
|
efficiency and function call overhead, you're much better off only
|
||
|
|
providing implementations for the hooks you'll be using.
|
||
|
|
|
||
|
|
"""
|
||
|
|
|
||
|
|
@classmethod
|
||
|
|
def _adapt_listener(cls, self, listener):
|
||
|
|
"""Adapt a :class:`.PoolListener` to individual
|
||
|
|
:class:`event.Dispatch` events.
|
||
|
|
|
||
|
|
"""
|
||
|
|
|
||
|
|
listener = util.as_interface(listener,
|
||
|
|
methods=('connect', 'first_connect',
|
||
|
|
'checkout', 'checkin'))
|
||
|
|
if hasattr(listener, 'connect'):
|
||
|
|
event.listen(self, 'connect', listener.connect)
|
||
|
|
if hasattr(listener, 'first_connect'):
|
||
|
|
event.listen(self, 'first_connect', listener.first_connect)
|
||
|
|
if hasattr(listener, 'checkout'):
|
||
|
|
event.listen(self, 'checkout', listener.checkout)
|
||
|
|
if hasattr(listener, 'checkin'):
|
||
|
|
event.listen(self, 'checkin', listener.checkin)
|
||
|
|
|
||
|
|
def connect(self, dbapi_con, con_record):
|
||
|
|
"""Called once for each new DB-API connection or Pool's ``creator()``.
|
||
|
|
|
||
|
|
dbapi_con
|
||
|
|
A newly connected raw DB-API connection (not a SQLAlchemy
|
||
|
|
``Connection`` wrapper).
|
||
|
|
|
||
|
|
con_record
|
||
|
|
The ``_ConnectionRecord`` that persistently manages the connection
|
||
|
|
|
||
|
|
"""
|
||
|
|
|
||
|
|
def first_connect(self, dbapi_con, con_record):
|
||
|
|
"""Called exactly once for the first DB-API connection.
|
||
|
|
|
||
|
|
dbapi_con
|
||
|
|
A newly connected raw DB-API connection (not a SQLAlchemy
|
||
|
|
``Connection`` wrapper).
|
||
|
|
|
||
|
|
con_record
|
||
|
|
The ``_ConnectionRecord`` that persistently manages the connection
|
||
|
|
|
||
|
|
"""
|
||
|
|
|
||
|
|
def checkout(self, dbapi_con, con_record, con_proxy):
|
||
|
|
"""Called when a connection is retrieved from the Pool.
|
||
|
|
|
||
|
|
dbapi_con
|
||
|
|
A raw DB-API connection
|
||
|
|
|
||
|
|
con_record
|
||
|
|
The ``_ConnectionRecord`` that persistently manages the connection
|
||
|
|
|
||
|
|
con_proxy
|
||
|
|
The ``_ConnectionFairy`` which manages the connection for the span of
|
||
|
|
the current checkout.
|
||
|
|
|
||
|
|
If you raise an ``exc.DisconnectionError``, the current
|
||
|
|
connection will be disposed and a fresh connection retrieved.
|
||
|
|
Processing of all checkout listeners will abort and restart
|
||
|
|
using the new connection.
|
||
|
|
"""
|
||
|
|
|
||
|
|
def checkin(self, dbapi_con, con_record):
|
||
|
|
"""Called when a connection returns to the pool.
|
||
|
|
|
||
|
|
Note that the connection may be closed, and may be None if the
|
||
|
|
connection has been invalidated. ``checkin`` will not be called
|
||
|
|
for detached connections. (They do not return to the pool.)
|
||
|
|
|
||
|
|
dbapi_con
|
||
|
|
A raw DB-API connection
|
||
|
|
|
||
|
|
con_record
|
||
|
|
The ``_ConnectionRecord`` that persistently manages the connection
|
||
|
|
|
||
|
|
"""
|
||
|
|
|
||
|
|
|
||
|
|
class ConnectionProxy(object):
|
||
|
|
"""Allows interception of statement execution by Connections.
|
||
|
|
|
||
|
|
.. note::
|
||
|
|
|
||
|
|
:class:`.ConnectionProxy` is deprecated. Please
|
||
|
|
refer to :class:`.ConnectionEvents`.
|
||
|
|
|
||
|
|
Either or both of the ``execute()`` and ``cursor_execute()``
|
||
|
|
may be implemented to intercept compiled statement and
|
||
|
|
cursor level executions, e.g.::
|
||
|
|
|
||
|
|
class MyProxy(ConnectionProxy):
|
||
|
|
def execute(self, conn, execute, clauseelement,
|
||
|
|
*multiparams, **params):
|
||
|
|
print "compiled statement:", clauseelement
|
||
|
|
return execute(clauseelement, *multiparams, **params)
|
||
|
|
|
||
|
|
def cursor_execute(self, execute, cursor, statement,
|
||
|
|
parameters, context, executemany):
|
||
|
|
print "raw statement:", statement
|
||
|
|
return execute(cursor, statement, parameters, context)
|
||
|
|
|
||
|
|
The ``execute`` argument is a function that will fulfill the default
|
||
|
|
execution behavior for the operation. The signature illustrated
|
||
|
|
in the example should be used.
|
||
|
|
|
||
|
|
The proxy is installed into an :class:`~sqlalchemy.engine.Engine` via
|
||
|
|
the ``proxy`` argument::
|
||
|
|
|
||
|
|
e = create_engine('someurl://', proxy=MyProxy())
|
||
|
|
|
||
|
|
"""
|
||
|
|
|
||
|
|
@classmethod
|
||
|
|
def _adapt_listener(cls, self, listener):
|
||
|
|
|
||
|
|
def adapt_execute(conn, clauseelement, multiparams, params):
|
||
|
|
|
||
|
|
def execute_wrapper(clauseelement, *multiparams, **params):
|
||
|
|
return clauseelement, multiparams, params
|
||
|
|
|
||
|
|
return listener.execute(conn, execute_wrapper,
|
||
|
|
clauseelement, *multiparams,
|
||
|
|
**params)
|
||
|
|
|
||
|
|
event.listen(self, 'before_execute', adapt_execute)
|
||
|
|
|
||
|
|
def adapt_cursor_execute(conn, cursor, statement,
|
||
|
|
parameters, context, executemany):
|
||
|
|
|
||
|
|
def execute_wrapper(
|
||
|
|
cursor,
|
||
|
|
statement,
|
||
|
|
parameters,
|
||
|
|
context,
|
||
|
|
):
|
||
|
|
return statement, parameters
|
||
|
|
|
||
|
|
return listener.cursor_execute(
|
||
|
|
execute_wrapper,
|
||
|
|
cursor,
|
||
|
|
statement,
|
||
|
|
parameters,
|
||
|
|
context,
|
||
|
|
executemany,
|
||
|
|
)
|
||
|
|
|
||
|
|
event.listen(self, 'before_cursor_execute', adapt_cursor_execute)
|
||
|
|
|
||
|
|
def do_nothing_callback(*arg, **kw):
|
||
|
|
pass
|
||
|
|
|
||
|
|
def adapt_listener(fn):
|
||
|
|
|
||
|
|
def go(conn, *arg, **kw):
|
||
|
|
fn(conn, do_nothing_callback, *arg, **kw)
|
||
|
|
|
||
|
|
return util.update_wrapper(go, fn)
|
||
|
|
|
||
|
|
event.listen(self, 'begin', adapt_listener(listener.begin))
|
||
|
|
event.listen(self, 'rollback',
|
||
|
|
adapt_listener(listener.rollback))
|
||
|
|
event.listen(self, 'commit', adapt_listener(listener.commit))
|
||
|
|
event.listen(self, 'savepoint',
|
||
|
|
adapt_listener(listener.savepoint))
|
||
|
|
event.listen(self, 'rollback_savepoint',
|
||
|
|
adapt_listener(listener.rollback_savepoint))
|
||
|
|
event.listen(self, 'release_savepoint',
|
||
|
|
adapt_listener(listener.release_savepoint))
|
||
|
|
event.listen(self, 'begin_twophase',
|
||
|
|
adapt_listener(listener.begin_twophase))
|
||
|
|
event.listen(self, 'prepare_twophase',
|
||
|
|
adapt_listener(listener.prepare_twophase))
|
||
|
|
event.listen(self, 'rollback_twophase',
|
||
|
|
adapt_listener(listener.rollback_twophase))
|
||
|
|
event.listen(self, 'commit_twophase',
|
||
|
|
adapt_listener(listener.commit_twophase))
|
||
|
|
|
||
|
|
def execute(self, conn, execute, clauseelement, *multiparams, **params):
|
||
|
|
"""Intercept high level execute() events."""
|
||
|
|
|
||
|
|
return execute(clauseelement, *multiparams, **params)
|
||
|
|
|
||
|
|
def cursor_execute(self, execute, cursor, statement, parameters,
|
||
|
|
context, executemany):
|
||
|
|
"""Intercept low-level cursor execute() events."""
|
||
|
|
|
||
|
|
return execute(cursor, statement, parameters, context)
|
||
|
|
|
||
|
|
def begin(self, conn, begin):
|
||
|
|
"""Intercept begin() events."""
|
||
|
|
|
||
|
|
return begin()
|
||
|
|
|
||
|
|
def rollback(self, conn, rollback):
|
||
|
|
"""Intercept rollback() events."""
|
||
|
|
|
||
|
|
return rollback()
|
||
|
|
|
||
|
|
def commit(self, conn, commit):
|
||
|
|
"""Intercept commit() events."""
|
||
|
|
|
||
|
|
return commit()
|
||
|
|
|
||
|
|
def savepoint(self, conn, savepoint, name=None):
|
||
|
|
"""Intercept savepoint() events."""
|
||
|
|
|
||
|
|
return savepoint(name=name)
|
||
|
|
|
||
|
|
def rollback_savepoint(self, conn, rollback_savepoint, name, context):
|
||
|
|
"""Intercept rollback_savepoint() events."""
|
||
|
|
|
||
|
|
return rollback_savepoint(name, context)
|
||
|
|
|
||
|
|
def release_savepoint(self, conn, release_savepoint, name, context):
|
||
|
|
"""Intercept release_savepoint() events."""
|
||
|
|
|
||
|
|
return release_savepoint(name, context)
|
||
|
|
|
||
|
|
def begin_twophase(self, conn, begin_twophase, xid):
|
||
|
|
"""Intercept begin_twophase() events."""
|
||
|
|
|
||
|
|
return begin_twophase(xid)
|
||
|
|
|
||
|
|
def prepare_twophase(self, conn, prepare_twophase, xid):
|
||
|
|
"""Intercept prepare_twophase() events."""
|
||
|
|
|
||
|
|
return prepare_twophase(xid)
|
||
|
|
|
||
|
|
def rollback_twophase(self, conn, rollback_twophase, xid, is_prepared):
|
||
|
|
"""Intercept rollback_twophase() events."""
|
||
|
|
|
||
|
|
return rollback_twophase(xid, is_prepared)
|
||
|
|
|
||
|
|
def commit_twophase(self, conn, commit_twophase, xid, is_prepared):
|
||
|
|
"""Intercept commit_twophase() events."""
|
||
|
|
|
||
|
|
return commit_twophase(xid, is_prepared)
|