text: # ext/asyncio/session.py
  # Copyright (C) 2020-2021 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 . import engine
  from . import result as _result
  from .base import ReversibleProxy
  from .base import StartableContext
  from ... import util
  from ...orm import object_session
  from ...orm import Session
  from ...orm import state as _instance_state
  from ...util.concurrency import greenlet_spawn
  
  _EXECUTE_OPTIONS = util.immutabledict({"prebuffer_rows": True})
  _STREAM_OPTIONS = util.immutabledict({"stream_results": True})
  
  
  @util.create_proxy_methods(
      Session,
      ":class:`_orm.Session`",
      ":class:`_asyncio.AsyncSession`",
      classmethods=["object_session", "identity_key"],
      methods=[
          "__contains__",
          "__iter__",
          "add",
          "add_all",
          "expire",
          "expire_all",
          "expunge",
          "expunge_all",
          "get_bind",
          "is_modified",
          "in_transaction",
          "in_nested_transaction",
      ],
      attributes=[
          "dirty",
          "deleted",
          "new",
          "identity_map",
          "is_active",
          "autoflush",
          "no_autoflush",
          "info",
      ],
  )
  class AsyncSession(ReversibleProxy):
      """Asyncio version of :class:`_orm.Session`.
  
      The :class:`_asyncio.AsyncSession` is a proxy for a traditional
      :class:`_orm.Session` instance.
  
      .. versionadded:: 1.4
  
      To use an :class:`_asyncio.AsyncSession` with custom :class:`_orm.Session`
      implementations, see the
      :paramref:`_asyncio.AsyncSession.sync_session_class` parameter.
  
  
      """
  
      _is_asyncio = True
  
      dispatch = None
  
      def __init__(self, bind=None, binds=None, sync_session_class=None, **kw):
          r"""Construct a new :class:`_asyncio.AsyncSession`.
  
          All parameters other than ``sync_session_class`` are passed to the
          ``sync_session_class`` callable directly to instantiate a new
          :class:`_orm.Session`. Refer to :meth:`_orm.Session.__init__` for
          parameter documentation.
  
          :param sync_session_class:
            A :class:`_orm.Session` subclass or other callable which will be used
            to construct the :class:`_orm.Session` which will be proxied. This
            parameter may be used to provide custom :class:`_orm.Session`
            subclasses. Defaults to the
            :attr:`_asyncio.AsyncSession.sync_session_class` class-level
            attribute.
  
            .. versionadded:: 1.4.24
  
          """
          kw["future"] = True
          if bind:
              self.bind = bind
              bind = engine._get_sync_engine_or_connection(bind)
  
          if binds:
              self.binds = binds
              binds = {
                  key: engine._get_sync_engine_or_connection(b)
                  for key, b in binds.items()
              }
  
          if sync_session_class:
              self.sync_session_class = sync_session_class
  
          self.sync_session = self._proxied = self._assign_proxied(
              self.sync_session_class(bind=bind, binds=binds, **kw)
          )
  
      sync_session_class = Session
      """The class or callable that provides the
      underlying :class:`_orm.Session` instance for a particular
      :class:`_asyncio.AsyncSession`.
  
      At the class level, this attribute is the default value for the
      :paramref:`_asyncio.AsyncSession.sync_session_class` parameter. Custom
      subclasses of :class:`_asyncio.AsyncSession` can override this.
  
      At the instance level, this attribute indicates the current class or
      callable that was used to provide the :class:`_orm.Session` instance for
      this :class:`_asyncio.AsyncSession` instance.
  
      .. versionadded:: 1.4.24
  
      """
  
      sync_session: Session
      """Reference to the underlying :class:`_orm.Session` this
      :class:`_asyncio.AsyncSession` proxies requests towards.
  
      This instance can be used as an event target.
  
      .. seealso::
  
          :ref:`asyncio_events`
  
      """
  
      async def refresh(
          self, instance, attribute_names=None, with_for_update=None
      ):
          """Expire and refresh the attributes on the given instance.
  
          A query will be issued to the database and all attributes will be
          refreshed with their current database value.
  
          This is the async version of the :meth:`_orm.Session.refresh` method.
          See that method for a complete description of all options.
  
          .. seealso::
  
              :meth:`_orm.Session.refresh` - main documentation for refresh
  
          """
  
          return await greenlet_spawn(
              self.sync_session.refresh,
              instance,
              attribute_names=attribute_names,
              with_for_update=with_for_update,
          )
  
      async def run_sync(self, fn, *arg, **kw):
          """Invoke the given sync callable passing sync self as the first
          argument.
  
          This method maintains the asyncio event loop all the way through
          to the database connection by running the given callable in a
          specially instrumented greenlet.
  
          E.g.::
  
              with AsyncSession(async_engine) as session:
                  await session.run_sync(some_business_method)
  
          .. note::
  
              The provided callable is invoked inline within the asyncio event
              loop, and will block on traditional IO calls.  IO within this
              callable should only call into SQLAlchemy's asyncio database
              APIs which will be properly adapted to the greenlet context.
  
          .. seealso::
  
              :ref:`session_run_sync`
          """
  
          return await greenlet_spawn(fn, self.sync_session, *arg, **kw)
  
      async def execute(
          self,
          statement,
          params=None,
          execution_options=util.EMPTY_DICT,
          bind_arguments=None,
          **kw
      ):
          """Execute a statement and return a buffered
          :class:`_engine.Result` object.
  
          .. seealso::
  
              :meth:`_orm.Session.execute` - main documentation for execute
  
          """
  
          if execution_options:
              execution_options = util.immutabledict(execution_options).union(
                  _EXECUTE_OPTIONS
              )
          else:
              execution_options = _EXECUTE_OPTIONS
  
          return await greenlet_spawn(
              self.sync_session.execute,
              statement,
              params=params,
              execution_options=execution_options,
              bind_arguments=bind_arguments,
              **kw
          )
  
      async def scalar(
          self,
          statement,
          params=None,
          execution_options=util.EMPTY_DICT,
          bind_arguments=None,
          **kw
      ):
          """Execute a statement and return a scalar result.
  
          .. seealso::
  
              :meth:`_orm.Session.scalar` - main documentation for scalar
  
          """
  
          result = await self.execute(
              statement,
              params=params,
              execution_options=execution_options,
              bind_arguments=bind_arguments,
              **kw
          )
          return result.scalar()
  
      async def scalars(
          self,
          statement,
          params=None,
          execution_options=util.EMPTY_DICT,
          bind_arguments=None,
          **kw
      ):
          """Execute a statement and return scalar results.
  
          :return: a :class:`_result.ScalarResult` object
  
          .. versionadded:: 1.4.24
  
          .. seealso::
  
              :meth:`_orm.Session.scalars` - main documentation for scalars
  
              :meth:`_asyncio.AsyncSession.stream_scalars` - streaming version
  
          """
  
          result = await self.execute(
              statement,
              params=params,
              execution_options=execution_options,
              bind_arguments=bind_arguments,
              **kw
          )
          return result.scalars()
  
      async def get(
          self,
          entity,
          ident,
          options=None,
          populate_existing=False,
          with_for_update=None,
          identity_token=None,
      ):
          """Return an instance based on the given primary key identifier,
          or ``None`` if not found.
  
          .. seealso::
  
              :meth:`_orm.Session.get` - main documentation for get
  
  
          """
          return await greenlet_spawn(
              self.sync_session.get,
              entity,
              ident,
              options=options,
              populate_existing=populate_existing,
              with_for_update=with_for_update,
              identity_token=identity_token,
          )
  
      async def stream(
          self,
          statement,
          params=None,
          execution_options=util.EMPTY_DICT,
          bind_arguments=None,
          **kw
      ):
          """Execute a statement and return a streaming
          :class:`_asyncio.AsyncResult` object."""
  
          if execution_options:
              execution_options = util.immutabledict(execution_options).union(
                  _STREAM_OPTIONS
              )
          else:
              execution_options = _STREAM_OPTIONS
  
          result = await greenlet_spawn(
              self.sync_session.execute,
              statement,
              params=params,
              execution_options=execution_options,
              bind_arguments=bind_arguments,
              **kw
          )
          return _result.AsyncResult(result)
  
      async def stream_scalars(
          self,
          statement,
          params=None,
          execution_options=util.EMPTY_DICT,
          bind_arguments=None,
          **kw
      ):
          """Execute a statement and return a stream of scalar results.
  
          :return: an :class:`_asyncio.AsyncScalarResult` object
  
          .. versionadded:: 1.4.24
  
          .. seealso::
  
              :meth:`_orm.Session.scalars` - main documentation for scalars
  
              :meth:`_asyncio.AsyncSession.scalars` - non streaming version
  
          """
  
          result = await self.stream(
              statement,
              params=params,
              execution_options=execution_options,
              bind_arguments=bind_arguments,
              **kw
          )
          return result.scalars()
  
      async def delete(self, instance):
          """Mark an instance as deleted.
  
          The database delete operation occurs upon ``flush()``.
  
          As this operation may need to cascade along unloaded relationships,
          it is awaitable to allow for those queries to take place.
  
          .. seealso::
  
              :meth:`_orm.Session.delete` - main documentation for delete
  
          """
          return await greenlet_spawn(self.sync_session.delete, instance)
  
      async def merge(self, instance, load=True, options=None):
          """Copy the state of a given instance into a corresponding instance
          within this :class:`_asyncio.AsyncSession`.
  
          .. seealso::
  
              :meth:`_orm.Session.merge` - main documentation for merge
  
          """
          return await greenlet_spawn(
              self.sync_session.merge, instance, load=load, options=options
          )
  
      async def flush(self, objects=None):
          """Flush all the object changes to the database.
  
          .. seealso::
  
              :meth:`_orm.Session.flush` - main documentation for flush
  
          """
          await greenlet_spawn(self.sync_session.flush, objects=objects)
  
      def get_transaction(self):
          """Return the current root transaction in progress, if any.
  
          :return: an :class:`_asyncio.AsyncSessionTransaction` object, or
           ``None``.
  
          .. versionadded:: 1.4.18
  
          """
          trans = self.sync_session.get_transaction()
          if trans is not None:
              return AsyncSessionTransaction._retrieve_proxy_for_target(trans)
          else:
              return None
  
      def get_nested_transaction(self):
          """Return the current nested transaction in progress, if any.
  
          :return: an :class:`_asyncio.AsyncSessionTransaction` object, or
           ``None``.
  
          .. versionadded:: 1.4.18
  
          """
  
          trans = self.sync_session.get_nested_transaction()
          if trans is not None:
              return AsyncSessionTransaction._retrieve_proxy_for_target(trans)
          else:
              return None
  
      async def connection(self, **kw):
          r"""Return a :class:`_asyncio.AsyncConnection` object corresponding to
          this :class:`.Session` object's transactional state.
  
          This method may also be used to establish execution options for the
          database connection used by the current transaction.
  
          .. versionadded:: 1.4.24  Added **kw arguments which are passed through
             to the underlying :meth:`_orm.Session.connection` method.
  
          .. seealso::
  
              :meth:`_orm.Session.connection` - main documentation for
              "connection"
  
          """
  
          sync_connection = await greenlet_spawn(
              self.sync_session.connection, **kw
          )
          return engine.AsyncConnection._retrieve_proxy_for_target(
              sync_connection
          )
  
      def begin(self, **kw):
          """Return an :class:`_asyncio.AsyncSessionTransaction` object.
  
          The underlying :class:`_orm.Session` will perform the
          "begin" action when the :class:`_asyncio.AsyncSessionTransaction`
          object is entered::
  
              async with async_session.begin():
                  # .. ORM transaction is begun
  
          Note that database IO will not normally occur when the session-level
          transaction is begun, as database transactions begin on an
          on-demand basis.  However, the begin block is async to accommodate
          for a :meth:`_orm.SessionEvents.after_transaction_create`
          event hook that may perform IO.
  
          For a general description of ORM begin, see
          :meth:`_orm.Session.begin`.
  
          """
  
          return AsyncSessionTransaction(self)
  
      def begin_nested(self, **kw):
          """Return an :class:`_asyncio.AsyncSessionTransaction` object
          which will begin a "nested" transaction, e.g. SAVEPOINT.
  
          Behavior is the same as that of :meth:`_asyncio.AsyncSession.begin`.
  
          For a general description of ORM begin nested, see
          :meth:`_orm.Session.begin_nested`.
  
          """
  
          return AsyncSessionTransaction(self, nested=True)
  
      async def rollback(self):
          """Rollback the current transaction in progress."""
          return await greenlet_spawn(self.sync_session.rollback)
  
      async def commit(self):
          """Commit the current transaction in progress."""
          return await greenlet_spawn(self.sync_session.commit)
  
      async def close(self):
          """Close out the transactional resources and ORM objects used by this
          :class:`_asyncio.AsyncSession`.
  
          This expunges all ORM objects associated with this
          :class:`_asyncio.AsyncSession`, ends any transaction in progress and
          :term:`releases` any :class:`_asyncio.AsyncConnection` objects which
          this :class:`_asyncio.AsyncSession` itself has checked out from
          associated :class:`_asyncio.AsyncEngine` objects. The operation then
          leaves the :class:`_asyncio.AsyncSession` in a state which it may be
          used again.
  
          .. tip::
  
              The :meth:`_asyncio.AsyncSession.close` method **does not prevent
              the Session from being used again**. The
              :class:`_asyncio.AsyncSession` itself does not actually have a
              distinct "closed" state; it merely means the
              :class:`_asyncio.AsyncSession` will release all database
              connections and ORM objects.
  
  
          .. seealso::
  
              :ref:`session_closing` - detail on the semantics of
              :meth:`_asyncio.AsyncSession.close`
  
          """
          return await greenlet_spawn(self.sync_session.close)
  
      @classmethod
      async def close_all(self):
          """Close all :class:`_asyncio.AsyncSession` sessions."""
          return await greenlet_spawn(self.sync_session.close_all)
  
      async def __aenter__(self):
          return self
  
      async def __aexit__(self, type_, value, traceback):
          await self.close()
  
      def _maker_context_manager(self):
          # no @contextlib.asynccontextmanager until python3.7, gr
          return _AsyncSessionContextManager(self)
  
  
  class _AsyncSessionContextManager:
      def __init__(self, async_session):
          self.async_session = async_session
  
      async def __aenter__(self):
          self.trans = self.async_session.begin()
          await self.trans.__aenter__()
          return self.async_session
  
      async def __aexit__(self, type_, value, traceback):
          await self.trans.__aexit__(type_, value, traceback)
          await self.async_session.__aexit__(type_, value, traceback)
  
  
  class AsyncSessionTransaction(ReversibleProxy, StartableContext):
      """A wrapper for the ORM :class:`_orm.SessionTransaction` object.
  
      This object is provided so that a transaction-holding object
      for the :meth:`_asyncio.AsyncSession.begin` may be returned.
  
      The object supports both explicit calls to
      :meth:`_asyncio.AsyncSessionTransaction.commit` and
      :meth:`_asyncio.AsyncSessionTransaction.rollback`, as well as use as an
      async context manager.
  
  
      .. versionadded:: 1.4
  
      """
  
      __slots__ = ("session", "sync_transaction", "nested")
  
      def __init__(self, session, nested=False):
          self.session = session
          self.nested = nested
          self.sync_transaction = None
  
      @property
      def is_active(self):
          return (
              self._sync_transaction() is not None
              and self._sync_transaction().is_active
          )
  
      def _sync_transaction(self):
          if not self.sync_transaction:
              self._raise_for_not_started()
          return self.sync_transaction
  
      async def rollback(self):
          """Roll back this :class:`_asyncio.AsyncTransaction`."""
          await greenlet_spawn(self._sync_transaction().rollback)
  
      async def commit(self):
          """Commit this :class:`_asyncio.AsyncTransaction`."""
  
          await greenlet_spawn(self._sync_transaction().commit)
  
      async def start(self, is_ctxmanager=False):
          self.sync_transaction = self._assign_proxied(
              await greenlet_spawn(
                  self.session.sync_session.begin_nested
                  if self.nested
                  else self.session.sync_session.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 async_object_session(instance):
      """Return the :class:`_asyncio.AsyncSession` to which the given instance
      belongs.
  
      This function makes use of the sync-API function
      :class:`_orm.object_session` to retrieve the :class:`_orm.Session` which
      refers to the given instance, and from there links it to the original
      :class:`_asyncio.AsyncSession`.
  
      If the :class:`_asyncio.AsyncSession` has been garbage collected, the
      return value is ``None``.
  
      This functionality is also available from the
      :attr:`_orm.InstanceState.async_session` accessor.
  
      :param instance: an ORM mapped instance
      :return: an :class:`_asyncio.AsyncSession` object, or ``None``.
  
      .. versionadded:: 1.4.18
  
      """
  
      session = object_session(instance)
      if session is not None:
          return async_session(session)
      else:
          return None
  
  
  def async_session(session):
      """Return the :class:`_asyncio.AsyncSession` which is proxying the given
      :class:`_orm.Session` object, if any.
  
      :param session: a :class:`_orm.Session` instance.
      :return: a :class:`_asyncio.AsyncSession` instance, or ``None``.
  
      .. versionadded:: 1.4.18
  
      """
      return AsyncSession._retrieve_proxy_for_target(session, regenerate=False)
  
  
  _instance_state._async_provider = async_session
  