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