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Diffstat (limited to 'lib/sqlalchemy/pool/events.py')
| -rw-r--r-- | lib/sqlalchemy/pool/events.py | 284 |
1 files changed, 284 insertions, 0 deletions
diff --git a/lib/sqlalchemy/pool/events.py b/lib/sqlalchemy/pool/events.py new file mode 100644 index 0000000..2829a58 --- /dev/null +++ b/lib/sqlalchemy/pool/events.py @@ -0,0 +1,284 @@ +# sqlalchemy/pool/events.py +# Copyright (C) 2005-2022 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 .base import Pool +from .. import event +from ..engine.base import Engine + + +class PoolEvents(event.Events): + """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://scott:tiger@localhost/test") + + # will associate with engine.pool + event.listen(engine, 'checkout', my_on_checkout) + + """ + + _target_class_doc = "SomeEngineOrPool" + _dispatch_target = Pool + + @classmethod + def _accept_with(cls, target): + if isinstance(target, type): + if issubclass(target, Engine): + return Pool + elif issubclass(target, Pool): + return target + elif isinstance(target, Engine): + return target.pool + elif isinstance(target, Pool): + return target + elif hasattr(target, "dispatch") and hasattr( + target.dispatch._events, "_no_async_engine_events" + ): + target.dispatch._events._no_async_engine_events() + else: + return None + + @classmethod + def _listen(cls, event_key, **kw): + target = event_key.dispatch_target + + kw.setdefault("asyncio", target._is_asyncio) + + event_key.base_listen(**kw) + + def connect(self, dbapi_connection, connection_record): + """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:`._ConnectionRecord.dbapi_connection` attribute. + + :param connection_record: the :class:`._ConnectionRecord` managing the + DBAPI connection. + + """ + + def first_connect(self, dbapi_connection, connection_record): + """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:`._ConnectionRecord.dbapi_connection` attribute. + + :param connection_record: the :class:`._ConnectionRecord` managing the + DBAPI connection. + + """ + + def checkout(self, dbapi_connection, connection_record, connection_proxy): + """Called when a connection is retrieved from the Pool. + + :param dbapi_connection: a DBAPI connection. + The :attr:`._ConnectionRecord.dbapi_connection` attribute. + + :param connection_record: the :class:`._ConnectionRecord` managing the + DBAPI connection. + + :param connection_proxy: the :class:`._ConnectionFairy` 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, connection_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.) + + :param dbapi_connection: a DBAPI connection. + The :attr:`._ConnectionRecord.dbapi_connection` attribute. + + :param connection_record: the :class:`._ConnectionRecord` managing the + DBAPI connection. + + """ + + def reset(self, dbapi_connection, connection_record): + """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. The behavior of "reset" can + be controlled, including disabled, using the ``reset_on_return`` + pool argument. + + + The :meth:`_events.PoolEvents.reset` event is usually followed by the + :meth:`_events.PoolEvents.checkin` event is called, except in those + cases where the connection is discarded immediately after reset. + + :param dbapi_connection: a DBAPI connection. + The :attr:`._ConnectionRecord.dbapi_connection` attribute. + + :param connection_record: the :class:`._ConnectionRecord` managing the + DBAPI connection. + + .. seealso:: + + :meth:`_events.ConnectionEvents.rollback` + + :meth:`_events.ConnectionEvents.commit` + + """ + + def invalidate(self, dbapi_connection, connection_record, exception): + """Called when a DBAPI connection is to be "invalidated". + + This event is called any time the :meth:`._ConnectionRecord.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:`._ConnectionRecord.dbapi_connection` attribute. + + :param connection_record: the :class:`._ConnectionRecord` managing the + DBAPI connection. + + :param exception: the exception object corresponding to the reason + for this invalidation, if any. May be ``None``. + + .. versionadded:: 0.9.2 Added support for connection invalidation + listening. + + .. seealso:: + + :ref:`pool_connection_invalidation` + + """ + + def soft_invalidate(self, dbapi_connection, connection_record, exception): + """Called when a DBAPI connection is to be "soft invalidated". + + This event is called any time the :meth:`._ConnectionRecord.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. + + .. versionadded:: 1.0.3 + + :param dbapi_connection: a DBAPI connection. + The :attr:`._ConnectionRecord.dbapi_connection` attribute. + + :param connection_record: the :class:`._ConnectionRecord` 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, connection_record): + """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`. + + .. versionadded:: 1.1 + + :param dbapi_connection: a DBAPI connection. + The :attr:`._ConnectionRecord.dbapi_connection` attribute. + + :param connection_record: the :class:`._ConnectionRecord` managing the + DBAPI connection. + + """ + + def detach(self, dbapi_connection, connection_record): + """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. + + .. versionadded:: 1.1 + + :param dbapi_connection: a DBAPI connection. + The :attr:`._ConnectionRecord.dbapi_connection` attribute. + + :param connection_record: the :class:`._ConnectionRecord` managing the + DBAPI connection. + + """ + + def close_detached(self, dbapi_connection): + """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. + + .. versionadded:: 1.1 + + :param dbapi_connection: a DBAPI connection. + The :attr:`._ConnectionRecord.dbapi_connection` attribute. + + """ |