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opt
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hc_python
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lib
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python3.12
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site-packages
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sqlalchemy
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pool
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/opt/hc_python/lib/python3.12/site-packages/sqlalchemy/pool/events.py
# pool/events.py # Copyright (C) 2005-2025 the SQLAlchemy authors and contributors # <see AUTHORS file> # # This module is part of SQLAlchemy and is released under # the MIT License: https://www.opensource.org/licenses/mit-license.php from __future__ import annotations import typing from typing import Any from typing import Optional from typing import Type from typing import Union from .base import ConnectionPoolEntry from .base import Pool from .base import PoolProxiedConnection from .base import PoolResetState from .. import event from .. import util if typing.TYPE_CHECKING: from ..engine import Engine from ..engine.interfaces import DBAPIConnection class PoolEvents(event.Events[Pool]): """Available events for :class:`_pool.Pool`. The methods here define the name of an event as well as the names of members that are passed to listener functions. e.g.:: from sqlalchemy import event def my_on_checkout(dbapi_conn, connection_rec, connection_proxy): "handle an on checkout event" event.listen(Pool, "checkout", my_on_checkout) In addition to accepting the :class:`_pool.Pool` class and :class:`_pool.Pool` instances, :class:`_events.PoolEvents` also accepts :class:`_engine.Engine` objects and the :class:`_engine.Engine` class as targets, which will be resolved to the ``.pool`` attribute of the given engine or the :class:`_pool.Pool` class:: engine = create_engine("postgresql+psycopg2://scott:tiger@localhost/test") # will associate with engine.pool event.listen(engine, "checkout", my_on_checkout) """ # noqa: E501 _target_class_doc = "SomeEngineOrPool" _dispatch_target = Pool @util.preload_module("sqlalchemy.engine") @classmethod def _accept_with( cls, target: Union[Pool, Type[Pool], Engine, Type[Engine]], identifier: str, ) -> Optional[Union[Pool, Type[Pool]]]: if not typing.TYPE_CHECKING: Engine = util.preloaded.engine.Engine if isinstance(target, type): if issubclass(target, Engine): return Pool else: assert issubclass(target, Pool) return target elif isinstance(target, Engine): return target.pool elif isinstance(target, Pool): return target elif hasattr(target, "_no_async_engine_events"): target._no_async_engine_events() else: return None @classmethod def _listen( cls, event_key: event._EventKey[Pool], **kw: Any, ) -> None: target = event_key.dispatch_target kw.setdefault("asyncio", target._is_asyncio) event_key.base_listen(**kw) def connect( self, dbapi_connection: DBAPIConnection, connection_record: ConnectionPoolEntry, ) -> None: """Called at the moment a particular DBAPI connection is first created for a given :class:`_pool.Pool`. This event allows one to capture the point directly after which the DBAPI module-level ``.connect()`` method has been used in order to produce a new DBAPI connection. :param dbapi_connection: a DBAPI connection. The :attr:`.ConnectionPoolEntry.dbapi_connection` attribute. :param connection_record: the :class:`.ConnectionPoolEntry` managing the DBAPI connection. """ def first_connect( self, dbapi_connection: DBAPIConnection, connection_record: ConnectionPoolEntry, ) -> None: """Called exactly once for the first time a DBAPI connection is checked out from a particular :class:`_pool.Pool`. The rationale for :meth:`_events.PoolEvents.first_connect` is to determine information about a particular series of database connections based on the settings used for all connections. Since a particular :class:`_pool.Pool` refers to a single "creator" function (which in terms of a :class:`_engine.Engine` refers to the URL and connection options used), it is typically valid to make observations about a single connection that can be safely assumed to be valid about all subsequent connections, such as the database version, the server and client encoding settings, collation settings, and many others. :param dbapi_connection: a DBAPI connection. The :attr:`.ConnectionPoolEntry.dbapi_connection` attribute. :param connection_record: the :class:`.ConnectionPoolEntry` managing the DBAPI connection. """ def checkout( self, dbapi_connection: DBAPIConnection, connection_record: ConnectionPoolEntry, connection_proxy: PoolProxiedConnection, ) -> None: """Called when a connection is retrieved from the Pool. :param dbapi_connection: a DBAPI connection. The :attr:`.ConnectionPoolEntry.dbapi_connection` attribute. :param connection_record: the :class:`.ConnectionPoolEntry` managing the DBAPI connection. :param connection_proxy: the :class:`.PoolProxiedConnection` object which will proxy the public interface of the DBAPI connection for the lifespan of the checkout. If you raise a :class:`~sqlalchemy.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. .. seealso:: :meth:`_events.ConnectionEvents.engine_connect` - a similar event which occurs upon creation of a new :class:`_engine.Connection`. """ def checkin( self, dbapi_connection: Optional[DBAPIConnection], connection_record: ConnectionPoolEntry, ) -> None: """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.) :param dbapi_connection: a DBAPI connection. The :attr:`.ConnectionPoolEntry.dbapi_connection` attribute. :param connection_record: the :class:`.ConnectionPoolEntry` managing the DBAPI connection. """ @event._legacy_signature( "2.0", ["dbapi_connection", "connection_record"], lambda dbapi_connection, connection_record, reset_state: ( dbapi_connection, connection_record, ), ) def reset( self, dbapi_connection: DBAPIConnection, connection_record: ConnectionPoolEntry, reset_state: PoolResetState, ) -> None: """Called before the "reset" action occurs for a pooled connection. This event represents when the ``rollback()`` method is called on the DBAPI connection before it is returned to the pool or discarded. A custom "reset" strategy may be implemented using this event hook, which may also be combined with disabling the default "reset" behavior using the :paramref:`_pool.Pool.reset_on_return` parameter. The primary difference between the :meth:`_events.PoolEvents.reset` and :meth:`_events.PoolEvents.checkin` events are that :meth:`_events.PoolEvents.reset` is called not just for pooled connections that are being returned to the pool, but also for connections that were detached using the :meth:`_engine.Connection.detach` method as well as asyncio connections that are being discarded due to garbage collection taking place on connections before the connection was checked in. Note that the event **is not** invoked for connections that were invalidated using :meth:`_engine.Connection.invalidate`. These events may be intercepted using the :meth:`.PoolEvents.soft_invalidate` and :meth:`.PoolEvents.invalidate` event hooks, and all "connection close" events may be intercepted using :meth:`.PoolEvents.close`. The :meth:`_events.PoolEvents.reset` event is usually followed by the :meth:`_events.PoolEvents.checkin` event, except in those cases where the connection is discarded immediately after reset. :param dbapi_connection: a DBAPI connection. The :attr:`.ConnectionPoolEntry.dbapi_connection` attribute. :param connection_record: the :class:`.ConnectionPoolEntry` managing the DBAPI connection. :param reset_state: :class:`.PoolResetState` instance which provides information about the circumstances under which the connection is being reset. .. versionadded:: 2.0 .. seealso:: :ref:`pool_reset_on_return` :meth:`_events.ConnectionEvents.rollback` :meth:`_events.ConnectionEvents.commit` """ def invalidate( self, dbapi_connection: DBAPIConnection, connection_record: ConnectionPoolEntry, exception: Optional[BaseException], ) -> None: """Called when a DBAPI connection is to be "invalidated". This event is called any time the :meth:`.ConnectionPoolEntry.invalidate` method is invoked, either from API usage or via "auto-invalidation", without the ``soft`` flag. The event occurs before a final attempt to call ``.close()`` on the connection occurs. :param dbapi_connection: a DBAPI connection. The :attr:`.ConnectionPoolEntry.dbapi_connection` attribute. :param connection_record: the :class:`.ConnectionPoolEntry` managing the DBAPI connection. :param exception: the exception object corresponding to the reason for this invalidation, if any. May be ``None``. .. seealso:: :ref:`pool_connection_invalidation` """ def soft_invalidate( self, dbapi_connection: DBAPIConnection, connection_record: ConnectionPoolEntry, exception: Optional[BaseException], ) -> None: """Called when a DBAPI connection is to be "soft invalidated". This event is called any time the :meth:`.ConnectionPoolEntry.invalidate` method is invoked with the ``soft`` flag. Soft invalidation refers to when the connection record that tracks this connection will force a reconnect after the current connection is checked in. It does not actively close the dbapi_connection at the point at which it is called. :param dbapi_connection: a DBAPI connection. The :attr:`.ConnectionPoolEntry.dbapi_connection` attribute. :param connection_record: the :class:`.ConnectionPoolEntry` managing the DBAPI connection. :param exception: the exception object corresponding to the reason for this invalidation, if any. May be ``None``. """ def close( self, dbapi_connection: DBAPIConnection, connection_record: ConnectionPoolEntry, ) -> None: """Called when a DBAPI connection is closed. The event is emitted before the close occurs. The close of a connection can fail; typically this is because the connection is already closed. If the close operation fails, the connection is discarded. The :meth:`.close` event corresponds to a connection that's still associated with the pool. To intercept close events for detached connections use :meth:`.close_detached`. :param dbapi_connection: a DBAPI connection. The :attr:`.ConnectionPoolEntry.dbapi_connection` attribute. :param connection_record: the :class:`.ConnectionPoolEntry` managing the DBAPI connection. """ def detach( self, dbapi_connection: DBAPIConnection, connection_record: ConnectionPoolEntry, ) -> None: """Called when a DBAPI connection is "detached" from a pool. This event is emitted after the detach occurs. The connection is no longer associated with the given connection record. :param dbapi_connection: a DBAPI connection. The :attr:`.ConnectionPoolEntry.dbapi_connection` attribute. :param connection_record: the :class:`.ConnectionPoolEntry` managing the DBAPI connection. """ def close_detached(self, dbapi_connection: DBAPIConnection) -> None: """Called when a detached DBAPI connection is closed. The event is emitted before the close occurs. The close of a connection can fail; typically this is because the connection is already closed. If the close operation fails, the connection is discarded. :param dbapi_connection: a DBAPI connection. The :attr:`.ConnectionPoolEntry.dbapi_connection` attribute. """
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