712 lines
22 KiB
Python
712 lines
22 KiB
Python
# ext/asyncio/engine.py
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# Copyright (C) 2020-2021 the SQLAlchemy authors and contributors
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# <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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from . import exc as async_exc
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from .base import ProxyComparable
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from .base import StartableContext
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from .result import AsyncResult
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from ... import exc
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from ... import util
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from ...engine import create_engine as _create_engine
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from ...engine.base import NestedTransaction
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from ...future import Connection
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from ...future import Engine
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from ...util.concurrency import greenlet_spawn
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def create_async_engine(*arg, **kw):
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"""Create a new async engine instance.
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Arguments passed to :func:`_asyncio.create_async_engine` are mostly
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identical to those passed to the :func:`_sa.create_engine` function.
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The specified dialect must be an asyncio-compatible dialect
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such as :ref:`dialect-postgresql-asyncpg`.
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.. versionadded:: 1.4
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"""
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if kw.get("server_side_cursors", False):
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raise async_exc.AsyncMethodRequired(
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"Can't set server_side_cursors for async engine globally; "
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"use the connection.stream() method for an async "
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"streaming result set"
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)
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kw["future"] = True
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sync_engine = _create_engine(*arg, **kw)
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return AsyncEngine(sync_engine)
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class AsyncConnectable:
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__slots__ = "_slots_dispatch", "__weakref__"
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@util.create_proxy_methods(
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Connection,
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":class:`_future.Connection`",
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":class:`_asyncio.AsyncConnection`",
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classmethods=[],
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methods=[],
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attributes=[
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"closed",
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"invalidated",
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"dialect",
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"default_isolation_level",
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],
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)
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class AsyncConnection(ProxyComparable, StartableContext, AsyncConnectable):
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"""An asyncio proxy for a :class:`_engine.Connection`.
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:class:`_asyncio.AsyncConnection` is acquired using the
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:meth:`_asyncio.AsyncEngine.connect`
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method of :class:`_asyncio.AsyncEngine`::
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from sqlalchemy.ext.asyncio import create_async_engine
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engine = create_async_engine("postgresql+asyncpg://user:pass@host/dbname")
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async with engine.connect() as conn:
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result = await conn.execute(select(table))
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.. versionadded:: 1.4
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""" # noqa
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# AsyncConnection is a thin proxy; no state should be added here
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# that is not retrievable from the "sync" engine / connection, e.g.
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# current transaction, info, etc. It should be possible to
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# create a new AsyncConnection that matches this one given only the
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# "sync" elements.
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__slots__ = (
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"sync_engine",
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"sync_connection",
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)
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def __init__(self, async_engine, sync_connection=None):
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self.engine = async_engine
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self.sync_engine = async_engine.sync_engine
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self.sync_connection = self._assign_proxied(sync_connection)
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@classmethod
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def _regenerate_proxy_for_target(cls, target):
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return AsyncConnection(
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AsyncEngine._retrieve_proxy_for_target(target.engine), target
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)
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async def start(self, is_ctxmanager=False):
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"""Start this :class:`_asyncio.AsyncConnection` object's context
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outside of using a Python ``with:`` block.
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"""
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if self.sync_connection:
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raise exc.InvalidRequestError("connection is already started")
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self.sync_connection = self._assign_proxied(
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await (greenlet_spawn(self.sync_engine.connect))
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)
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return self
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@property
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def connection(self):
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"""Not implemented for async; call
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:meth:`_asyncio.AsyncConnection.get_raw_connection`.
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"""
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raise exc.InvalidRequestError(
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"AsyncConnection.connection accessor is not implemented as the "
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"attribute may need to reconnect on an invalidated connection. "
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"Use the get_raw_connection() method."
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)
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async def get_raw_connection(self):
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"""Return the pooled DBAPI-level connection in use by this
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:class:`_asyncio.AsyncConnection`.
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This is typically the SQLAlchemy connection-pool proxied connection
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which then has an attribute .connection that refers to the actual
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DBAPI-level connection.
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"""
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conn = self._sync_connection()
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return await greenlet_spawn(getattr, conn, "connection")
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@property
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def _proxied(self):
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return self.sync_connection
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@property
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def info(self):
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"""Return the :attr:`_engine.Connection.info` dictionary of the
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underlying :class:`_engine.Connection`.
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This dictionary is freely writable for user-defined state to be
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associated with the database connection.
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This attribute is only available if the :class:`.AsyncConnection` is
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currently connected. If the :attr:`.AsyncConnection.closed` attribute
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is ``True``, then accessing this attribute will raise
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:class:`.ResourceClosedError`.
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.. versionadded:: 1.4.0b2
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"""
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return self.sync_connection.info
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def _sync_connection(self):
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if not self.sync_connection:
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self._raise_for_not_started()
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return self.sync_connection
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def begin(self):
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"""Begin a transaction prior to autobegin occurring."""
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self._sync_connection()
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return AsyncTransaction(self)
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def begin_nested(self):
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"""Begin a nested transaction and return a transaction handle."""
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self._sync_connection()
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return AsyncTransaction(self, nested=True)
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async def invalidate(self, exception=None):
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"""Invalidate the underlying DBAPI connection associated with
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this :class:`_engine.Connection`.
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See the method :meth:`_engine.Connection.invalidate` for full
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detail on this method.
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"""
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conn = self._sync_connection()
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return await greenlet_spawn(conn.invalidate, exception=exception)
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async def get_isolation_level(self):
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conn = self._sync_connection()
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return await greenlet_spawn(conn.get_isolation_level)
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async def set_isolation_level(self):
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conn = self._sync_connection()
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return await greenlet_spawn(conn.get_isolation_level)
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def in_transaction(self):
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"""Return True if a transaction is in progress.
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.. versionadded:: 1.4.0b2
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"""
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conn = self._sync_connection()
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return conn.in_transaction()
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def in_nested_transaction(self):
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"""Return True if a transaction is in progress.
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.. versionadded:: 1.4.0b2
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"""
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conn = self._sync_connection()
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return conn.in_nested_transaction()
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def get_transaction(self):
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"""Return an :class:`.AsyncTransaction` representing the current
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transaction, if any.
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This makes use of the underlying synchronous connection's
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:meth:`_engine.Connection.get_transaction` method to get the current
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:class:`_engine.Transaction`, which is then proxied in a new
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:class:`.AsyncTransaction` object.
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.. versionadded:: 1.4.0b2
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"""
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conn = self._sync_connection()
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trans = conn.get_transaction()
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if trans is not None:
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return AsyncTransaction._retrieve_proxy_for_target(trans)
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else:
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return None
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def get_nested_transaction(self):
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"""Return an :class:`.AsyncTransaction` representing the current
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nested (savepoint) transaction, if any.
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This makes use of the underlying synchronous connection's
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:meth:`_engine.Connection.get_nested_transaction` method to get the
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current :class:`_engine.Transaction`, which is then proxied in a new
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:class:`.AsyncTransaction` object.
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.. versionadded:: 1.4.0b2
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"""
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conn = self._sync_connection()
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trans = conn.get_nested_transaction()
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if trans is not None:
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return AsyncTransaction._retrieve_proxy_for_target(trans)
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else:
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return None
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async def execution_options(self, **opt):
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r"""Set non-SQL options for the connection which take effect
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during execution.
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This returns this :class:`_asyncio.AsyncConnection` object with
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the new options added.
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See :meth:`_future.Connection.execution_options` for full details
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on this method.
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"""
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conn = self._sync_connection()
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c2 = await greenlet_spawn(conn.execution_options, **opt)
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assert c2 is conn
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return self
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async def commit(self):
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"""Commit the transaction that is currently in progress.
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This method commits the current transaction if one has been started.
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If no transaction was started, the method has no effect, assuming
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the connection is in a non-invalidated state.
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A transaction is begun on a :class:`_future.Connection` automatically
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whenever a statement is first executed, or when the
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:meth:`_future.Connection.begin` method is called.
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"""
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conn = self._sync_connection()
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await greenlet_spawn(conn.commit)
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async def rollback(self):
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"""Roll back the transaction that is currently in progress.
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This method rolls back the current transaction if one has been started.
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If no transaction was started, the method has no effect. If a
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transaction was started and the connection is in an invalidated state,
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the transaction is cleared using this method.
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A transaction is begun on a :class:`_future.Connection` automatically
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whenever a statement is first executed, or when the
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:meth:`_future.Connection.begin` method is called.
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"""
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conn = self._sync_connection()
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await greenlet_spawn(conn.rollback)
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async def close(self):
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"""Close this :class:`_asyncio.AsyncConnection`.
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This has the effect of also rolling back the transaction if one
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is in place.
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"""
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conn = self._sync_connection()
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await greenlet_spawn(conn.close)
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async def exec_driver_sql(
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self,
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statement,
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parameters=None,
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execution_options=util.EMPTY_DICT,
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):
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r"""Executes a driver-level SQL string and return buffered
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:class:`_engine.Result`.
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"""
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conn = self._sync_connection()
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result = await greenlet_spawn(
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conn.exec_driver_sql,
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statement,
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parameters,
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execution_options,
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_require_await=True,
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)
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if result.context._is_server_side:
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raise async_exc.AsyncMethodRequired(
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"Can't use the connection.exec_driver_sql() method with a "
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"server-side cursor."
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"Use the connection.stream() method for an async "
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"streaming result set."
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)
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return result
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async def stream(
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self,
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statement,
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parameters=None,
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execution_options=util.EMPTY_DICT,
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):
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"""Execute a statement and return a streaming
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:class:`_asyncio.AsyncResult` object."""
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conn = self._sync_connection()
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result = await greenlet_spawn(
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conn._execute_20,
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statement,
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parameters,
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util.EMPTY_DICT.merge_with(
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execution_options, {"stream_results": True}
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),
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_require_await=True,
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)
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if not result.context._is_server_side:
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# TODO: real exception here
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assert False, "server side result expected"
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return AsyncResult(result)
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async def execute(
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self,
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statement,
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parameters=None,
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execution_options=util.EMPTY_DICT,
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):
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r"""Executes a SQL statement construct and return a buffered
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:class:`_engine.Result`.
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:param object: The statement to be executed. This is always
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an object that is in both the :class:`_expression.ClauseElement` and
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:class:`_expression.Executable` hierarchies, including:
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* :class:`_expression.Select`
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* :class:`_expression.Insert`, :class:`_expression.Update`,
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:class:`_expression.Delete`
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* :class:`_expression.TextClause` and
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:class:`_expression.TextualSelect`
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* :class:`_schema.DDL` and objects which inherit from
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:class:`_schema.DDLElement`
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:param parameters: parameters which will be bound into the statement.
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This may be either a dictionary of parameter names to values,
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or a mutable sequence (e.g. a list) of dictionaries. When a
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list of dictionaries is passed, the underlying statement execution
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will make use of the DBAPI ``cursor.executemany()`` method.
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When a single dictionary is passed, the DBAPI ``cursor.execute()``
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method will be used.
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:param execution_options: optional dictionary of execution options,
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which will be associated with the statement execution. This
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dictionary can provide a subset of the options that are accepted
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by :meth:`_future.Connection.execution_options`.
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:return: a :class:`_engine.Result` object.
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"""
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conn = self._sync_connection()
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result = await greenlet_spawn(
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conn._execute_20,
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statement,
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parameters,
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execution_options,
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_require_await=True,
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)
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if result.context._is_server_side:
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raise async_exc.AsyncMethodRequired(
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"Can't use the connection.execute() method with a "
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"server-side cursor."
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"Use the connection.stream() method for an async "
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"streaming result set."
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)
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return result
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async def scalar(
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self,
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statement,
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parameters=None,
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execution_options=util.EMPTY_DICT,
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):
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r"""Executes a SQL statement construct and returns a scalar object.
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This method is shorthand for invoking the
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:meth:`_engine.Result.scalar` method after invoking the
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:meth:`_future.Connection.execute` method. Parameters are equivalent.
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:return: a scalar Python value representing the first column of the
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first row returned.
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"""
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result = await self.execute(statement, parameters, execution_options)
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return result.scalar()
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async def run_sync(self, fn, *arg, **kw):
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"""Invoke the given sync callable passing self as the first argument.
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This method maintains the asyncio event loop all the way through
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to the database connection by running the given callable in a
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specially instrumented greenlet.
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E.g.::
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with async_engine.begin() as conn:
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await conn.run_sync(metadata.create_all)
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.. note::
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The provided callable is invoked inline within the asyncio event
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loop, and will block on traditional IO calls. IO within this
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callable should only call into SQLAlchemy's asyncio database
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APIs which will be properly adapted to the greenlet context.
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.. seealso::
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:ref:`session_run_sync`
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"""
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conn = self._sync_connection()
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return await greenlet_spawn(fn, conn, *arg, **kw)
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def __await__(self):
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return self.start().__await__()
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async def __aexit__(self, type_, value, traceback):
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await self.close()
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@util.create_proxy_methods(
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Engine,
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":class:`_future.Engine`",
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":class:`_asyncio.AsyncEngine`",
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classmethods=[],
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methods=[
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"clear_compiled_cache",
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"update_execution_options",
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"get_execution_options",
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],
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attributes=["url", "pool", "dialect", "engine", "name", "driver", "echo"],
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)
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class AsyncEngine(ProxyComparable, AsyncConnectable):
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"""An asyncio proxy for a :class:`_engine.Engine`.
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:class:`_asyncio.AsyncEngine` is acquired using the
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:func:`_asyncio.create_async_engine` function::
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from sqlalchemy.ext.asyncio import create_async_engine
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engine = create_async_engine("postgresql+asyncpg://user:pass@host/dbname")
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|
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.. versionadded:: 1.4
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|
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""" # noqa
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# AsyncEngine is a thin proxy; no state should be added here
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# that is not retrievable from the "sync" engine / connection, e.g.
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# current transaction, info, etc. It should be possible to
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# create a new AsyncEngine that matches this one given only the
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# "sync" elements.
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__slots__ = ("sync_engine", "_proxied")
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_connection_cls = AsyncConnection
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_option_cls: type
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class _trans_ctx(StartableContext):
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def __init__(self, conn):
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self.conn = conn
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async def start(self, is_ctxmanager=False):
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await self.conn.start(is_ctxmanager=is_ctxmanager)
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self.transaction = self.conn.begin()
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await self.transaction.__aenter__()
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return self.conn
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async def __aexit__(self, type_, value, traceback):
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await self.transaction.__aexit__(type_, value, traceback)
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await self.conn.close()
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def __init__(self, sync_engine):
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if not sync_engine.dialect.is_async:
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raise exc.InvalidRequestError(
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"The asyncio extension requires an async driver to be used. "
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f"The loaded {sync_engine.dialect.driver!r} is not async."
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)
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self.sync_engine = self._proxied = self._assign_proxied(sync_engine)
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@classmethod
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def _regenerate_proxy_for_target(cls, target):
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return AsyncEngine(target)
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def begin(self):
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"""Return a context manager which when entered will deliver an
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:class:`_asyncio.AsyncConnection` with an
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:class:`_asyncio.AsyncTransaction` established.
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E.g.::
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async with async_engine.begin() as conn:
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await conn.execute(
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text("insert into table (x, y, z) values (1, 2, 3)")
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)
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await conn.execute(text("my_special_procedure(5)"))
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"""
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conn = self.connect()
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return self._trans_ctx(conn)
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def connect(self):
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"""Return an :class:`_asyncio.AsyncConnection` object.
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The :class:`_asyncio.AsyncConnection` will procure a database
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connection from the underlying connection pool when it is entered
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as an async context manager::
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async with async_engine.connect() as conn:
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result = await conn.execute(select(user_table))
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The :class:`_asyncio.AsyncConnection` may also be started outside of a
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|
context manager by invoking its :meth:`_asyncio.AsyncConnection.start`
|
|
method.
|
|
|
|
"""
|
|
|
|
return self._connection_cls(self)
|
|
|
|
async def raw_connection(self):
|
|
"""Return a "raw" DBAPI connection from the connection pool.
|
|
|
|
.. seealso::
|
|
|
|
:ref:`dbapi_connections`
|
|
|
|
"""
|
|
return await greenlet_spawn(self.sync_engine.raw_connection)
|
|
|
|
def execution_options(self, **opt):
|
|
"""Return a new :class:`_asyncio.AsyncEngine` that will provide
|
|
:class:`_asyncio.AsyncConnection` objects with the given execution
|
|
options.
|
|
|
|
Proxied from :meth:`_future.Engine.execution_options`. See that
|
|
method for details.
|
|
|
|
"""
|
|
|
|
return AsyncEngine(self.sync_engine.execution_options(**opt))
|
|
|
|
async def dispose(self):
|
|
"""Dispose of the connection pool used by this
|
|
:class:`_asyncio.AsyncEngine`.
|
|
|
|
This will close all connection pool connections that are
|
|
**currently checked in**. See the documentation for the underlying
|
|
:meth:`_future.Engine.dispose` method for further notes.
|
|
|
|
.. seealso::
|
|
|
|
:meth:`_future.Engine.dispose`
|
|
|
|
"""
|
|
|
|
return await greenlet_spawn(self.sync_engine.dispose)
|
|
|
|
|
|
class AsyncTransaction(ProxyComparable, StartableContext):
|
|
"""An asyncio proxy for a :class:`_engine.Transaction`."""
|
|
|
|
__slots__ = ("connection", "sync_transaction", "nested")
|
|
|
|
def __init__(self, connection, nested=False):
|
|
self.connection = connection # AsyncConnection
|
|
self.sync_transaction = None # sqlalchemy.engine.Transaction
|
|
self.nested = nested
|
|
|
|
@classmethod
|
|
def _regenerate_proxy_for_target(cls, target):
|
|
sync_connection = target.connection
|
|
sync_transaction = target
|
|
nested = isinstance(target, NestedTransaction)
|
|
|
|
async_connection = AsyncConnection._retrieve_proxy_for_target(
|
|
sync_connection
|
|
)
|
|
assert async_connection is not None
|
|
|
|
obj = cls.__new__(cls)
|
|
obj.connection = async_connection
|
|
obj.sync_transaction = obj._assign_proxied(sync_transaction)
|
|
obj.nested = nested
|
|
return obj
|
|
|
|
def _sync_transaction(self):
|
|
if not self.sync_transaction:
|
|
self._raise_for_not_started()
|
|
return self.sync_transaction
|
|
|
|
@property
|
|
def _proxied(self):
|
|
return self.sync_transaction
|
|
|
|
@property
|
|
def is_valid(self):
|
|
return self._sync_transaction().is_valid
|
|
|
|
@property
|
|
def is_active(self):
|
|
return self._sync_transaction().is_active
|
|
|
|
async def close(self):
|
|
"""Close this :class:`.Transaction`.
|
|
|
|
If this transaction is the base transaction in a begin/commit
|
|
nesting, the transaction will rollback(). Otherwise, the
|
|
method returns.
|
|
|
|
This is used to cancel a Transaction without affecting the scope of
|
|
an enclosing transaction.
|
|
|
|
"""
|
|
await greenlet_spawn(self._sync_transaction().close)
|
|
|
|
async def rollback(self):
|
|
"""Roll back this :class:`.Transaction`."""
|
|
await greenlet_spawn(self._sync_transaction().rollback)
|
|
|
|
async def commit(self):
|
|
"""Commit this :class:`.Transaction`."""
|
|
|
|
await greenlet_spawn(self._sync_transaction().commit)
|
|
|
|
async def start(self, is_ctxmanager=False):
|
|
"""Start this :class:`_asyncio.AsyncTransaction` object's context
|
|
outside of using a Python ``with:`` block.
|
|
|
|
"""
|
|
|
|
self.sync_transaction = self._assign_proxied(
|
|
await greenlet_spawn(
|
|
self.connection._sync_connection().begin_nested
|
|
if self.nested
|
|
else self.connection._sync_connection().begin
|
|
)
|
|
)
|
|
if is_ctxmanager:
|
|
self.sync_transaction.__enter__()
|
|
return self
|
|
|
|
async def __aexit__(self, type_, value, traceback):
|
|
await greenlet_spawn(
|
|
self._sync_transaction().__exit__, type_, value, traceback
|
|
)
|
|
|
|
|
|
def _get_sync_engine_or_connection(async_engine):
|
|
if isinstance(async_engine, AsyncConnection):
|
|
return async_engine.sync_connection
|
|
|
|
try:
|
|
return async_engine.sync_engine
|
|
except AttributeError as e:
|
|
raise exc.ArgumentError(
|
|
"AsyncEngine expected, got %r" % async_engine
|
|
) from e
|