273 lines
6.4 KiB
Python
273 lines
6.4 KiB
Python
import asyncio
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import json
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import aiopg
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from ..connection import TIMEOUT
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from ..utils import _ContextManager, get_running_loop
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from .connection import SAConnection
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try:
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from sqlalchemy.dialects.postgresql.psycopg2 import (
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PGCompiler_psycopg2,
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PGDialect_psycopg2,
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)
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except ImportError: # pragma: no cover
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raise ImportError("aiopg.sa requires sqlalchemy")
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class APGCompiler_psycopg2(PGCompiler_psycopg2):
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def construct_params(self, *args, **kwargs):
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pd = super().construct_params(*args, **kwargs)
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for column in self.prefetch:
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pd[column.key] = self._exec_default(column.default)
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return pd
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def _exec_default(self, default):
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if default.is_callable:
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return default.arg(self.dialect)
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else:
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return default.arg
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def get_dialect(json_serializer=json.dumps, json_deserializer=lambda x: x):
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dialect = PGDialect_psycopg2(
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json_serializer=json_serializer, json_deserializer=json_deserializer
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)
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dialect.statement_compiler = APGCompiler_psycopg2
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dialect.implicit_returning = True
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dialect.supports_native_enum = True
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dialect.supports_smallserial = True # 9.2+
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dialect._backslash_escapes = False
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dialect.supports_sane_multi_rowcount = True # psycopg 2.0.9+
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dialect._has_native_hstore = True
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return dialect
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_dialect = get_dialect()
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def create_engine(
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dsn=None,
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*,
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minsize=1,
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maxsize=10,
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dialect=_dialect,
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timeout=TIMEOUT,
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pool_recycle=-1,
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**kwargs
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):
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"""A coroutine for Engine creation.
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Returns Engine instance with embedded connection pool.
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The pool has *minsize* opened connections to PostgreSQL server.
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"""
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coro = _create_engine(
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dsn=dsn,
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minsize=minsize,
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maxsize=maxsize,
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dialect=dialect,
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timeout=timeout,
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pool_recycle=pool_recycle,
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**kwargs
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)
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return _ContextManager(coro, _close_engine)
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async def _create_engine(
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dsn=None,
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*,
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minsize=1,
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maxsize=10,
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dialect=_dialect,
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timeout=TIMEOUT,
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pool_recycle=-1,
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**kwargs
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):
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pool = await aiopg.create_pool(
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dsn,
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minsize=minsize,
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maxsize=maxsize,
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timeout=timeout,
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pool_recycle=pool_recycle,
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**kwargs
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)
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conn = await pool.acquire()
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try:
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real_dsn = conn.dsn
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return Engine(dialect, pool, real_dsn)
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finally:
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await pool.release(conn)
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async def _close_engine(engine: "Engine") -> None:
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engine.close()
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await engine.wait_closed()
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async def _close_connection(c: SAConnection) -> None:
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await c.close()
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class Engine:
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"""Connects a aiopg.Pool and
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sqlalchemy.engine.interfaces.Dialect together to provide a
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source of database connectivity and behavior.
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An Engine object is instantiated publicly using the
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create_engine coroutine.
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"""
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__slots__ = ("_dialect", "_pool", "_dsn", "_loop")
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def __init__(self, dialect, pool, dsn):
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self._dialect = dialect
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self._pool = pool
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self._dsn = dsn
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self._loop = get_running_loop()
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@property
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def dialect(self):
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"""An dialect for engine."""
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return self._dialect
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@property
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def name(self):
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"""A name of the dialect."""
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return self._dialect.name
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@property
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def driver(self):
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"""A driver of the dialect."""
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return self._dialect.driver
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@property
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def dsn(self):
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"""DSN connection info"""
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return self._dsn
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@property
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def timeout(self):
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return self._pool.timeout
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@property
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def minsize(self):
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return self._pool.minsize
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@property
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def maxsize(self):
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return self._pool.maxsize
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@property
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def size(self):
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return self._pool.size
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@property
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def freesize(self):
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return self._pool.freesize
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@property
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def closed(self):
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return self._pool.closed
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def close(self):
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"""Close engine.
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Mark all engine connections to be closed on getting back to pool.
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Closed engine doesn't allow to acquire new connections.
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"""
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self._pool.close()
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def terminate(self):
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"""Terminate engine.
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Terminate engine pool with instantly closing all acquired
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connections also.
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"""
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self._pool.terminate()
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async def wait_closed(self):
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"""Wait for closing all engine's connections."""
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await self._pool.wait_closed()
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def acquire(self):
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"""Get a connection from pool."""
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coro = self._acquire()
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return _ContextManager[SAConnection](coro, _close_connection)
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async def _acquire(self):
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raw = await self._pool.acquire()
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return SAConnection(raw, self)
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def release(self, conn):
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return self._pool.release(conn.connection)
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def __enter__(self):
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raise RuntimeError(
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'"await" should be used as context manager expression'
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)
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def __exit__(self, *args):
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# This must exist because __enter__ exists, even though that
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# always raises; that's how the with-statement works.
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pass # pragma: nocover
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def __await__(self):
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# This is not a coroutine. It is meant to enable the idiom:
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#
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# with (await engine) as conn:
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# <block>
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#
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# as an alternative to:
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#
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# conn = await engine.acquire()
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# try:
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# <block>
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# finally:
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# engine.release(conn)
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conn = yield from self._acquire().__await__()
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return _ConnectionContextManager(conn, self._loop)
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async def __aenter__(self):
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return self
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async def __aexit__(self, exc_type, exc_val, exc_tb):
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self.close()
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await self.wait_closed()
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class _ConnectionContextManager:
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"""Context manager.
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This enables the following idiom for acquiring and releasing a
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connection around a block:
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async with engine as conn:
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cur = await conn.cursor()
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while failing loudly when accidentally using:
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with engine:
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<block>
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"""
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__slots__ = ("_conn", "_loop")
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def __init__(self, conn: SAConnection, loop: asyncio.AbstractEventLoop):
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self._conn = conn
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self._loop = loop
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def __enter__(self):
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return self._conn
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def __exit__(self, *args):
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asyncio.ensure_future(self._conn.close(), loop=self._loop)
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self._conn = None
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