# ported from:
# https://github.com/aio-libs/aiopg/blob/master/aiopg/sa/engine.py
import asyncio
import aiomysql
from .connection import SAConnection
from .exc import InvalidRequestError, ArgumentError
from ..utils import _PoolContextManager, _PoolAcquireContextManager
from ..cursors import (
Cursor, DeserializationCursor, DictCursor, SSCursor, SSDictCursor)
try:
from sqlalchemy.dialects.mysql.pymysql import MySQLDialect_pymysql
from sqlalchemy.dialects.mysql.mysqldb import MySQLCompiler_mysqldb
except ImportError: # pragma: no cover
raise ImportError('aiomysql.sa requires sqlalchemy')
class MySQLCompiler_pymysql(MySQLCompiler_mysqldb):
def construct_params(self, params=None, _group_number=None, _check=True):
pd = super().construct_params(params, _group_number, _check)
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
_dialect = MySQLDialect_pymysql(paramstyle='pyformat')
_dialect.statement_compiler = MySQLCompiler_pymysql
_dialect.default_paramstyle = 'pyformat'
[docs]def create_engine(minsize=1, maxsize=10, loop=None,
dialect=_dialect, pool_recycle=-1, compiled_cache=None,
**kwargs):
"""A coroutine for Engine creation.
Returns Engine instance with embedded connection pool.
The pool has *minsize* opened connections to MySQL server.
"""
deprecated_cursor_classes = [
DeserializationCursor, DictCursor, SSCursor, SSDictCursor,
]
cursorclass = kwargs.get('cursorclass', Cursor)
if not issubclass(cursorclass, Cursor) or any(
issubclass(cursorclass, cursor_class)
for cursor_class in deprecated_cursor_classes
):
raise ArgumentError('SQLAlchemy engine does not support '
'this cursor class')
coro = _create_engine(minsize=minsize, maxsize=maxsize, loop=loop,
dialect=dialect, pool_recycle=pool_recycle,
compiled_cache=compiled_cache, **kwargs)
return _EngineContextManager(coro)
async def _create_engine(minsize=1, maxsize=10, loop=None,
dialect=_dialect, pool_recycle=-1,
compiled_cache=None, **kwargs):
if loop is None:
loop = asyncio.get_event_loop()
pool = await aiomysql.create_pool(minsize=minsize, maxsize=maxsize,
loop=loop,
pool_recycle=pool_recycle, **kwargs)
conn = await pool.acquire()
try:
return Engine(dialect, pool, compiled_cache=compiled_cache, **kwargs)
finally:
pool.release(conn)
[docs]class Engine:
"""Connects a aiomysql.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.
"""
def __init__(self, dialect, pool, compiled_cache=None, **kwargs):
self._dialect = dialect
self._pool = pool
self._compiled_cache = compiled_cache
self._conn_kw = kwargs
@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 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
[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 _EngineAcquireContextManager(coro, self)
async def _acquire(self):
raw = await self._pool.acquire()
conn = SAConnection(raw, self, compiled_cache=self._compiled_cache)
return conn
[docs] def release(self, conn):
"""Revert back connection to pool."""
if conn.in_transaction:
raise InvalidRequestError("Cannot release a connection with "
"not finished transaction")
raw = conn.connection
return self._pool.release(raw)
def __enter__(self):
raise RuntimeError(
'"yield from" 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 __iter__(self):
# This is not a coroutine. It is meant to enable the idiom:
#
# with (yield from engine) as conn:
# <block>
#
# as an alternative to:
#
# conn = yield from engine.acquire()
# try:
# <block>
# finally:
# engine.release(conn)
conn = yield from self.acquire()
return _ConnectionContextManager(self, conn)
async def __aenter__(self):
return self
async def __aexit__(self, exc_type, exc_val, exc_tb):
self.close()
await self.wait_closed()
_EngineContextManager = _PoolContextManager
_EngineAcquireContextManager = _PoolAcquireContextManager
class _ConnectionContextManager:
"""Context manager.
This enables the following idiom for acquiring and releasing a
connection around a block:
with (yield from engine) as conn:
cur = yield from conn.cursor()
while failing loudly when accidentally using:
with engine:
<block>
"""
__slots__ = ('_engine', '_conn')
def __init__(self, engine, conn):
self._engine = engine
self._conn = conn
def __enter__(self):
assert self._conn is not None
return self._conn
def __exit__(self, *args):
try:
self._engine.release(self._conn)
finally:
self._engine = None
self._conn = None