236 lines
6.8 KiB
Python
236 lines
6.8 KiB
Python
# ported from:
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# https://github.com/aio-libs/aiopg/blob/master/aiopg/sa/engine.py
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import asyncio
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import aiomysql
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from .connection import SAConnection
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from .exc import InvalidRequestError, ArgumentError
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from ..utils import _PoolContextManager, _PoolAcquireContextManager
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from ..cursors import (
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Cursor, DeserializationCursor, DictCursor, SSCursor, SSDictCursor)
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try:
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from sqlalchemy.dialects.mysql.pymysql import MySQLDialect_pymysql
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from sqlalchemy.dialects.mysql.mysqldb import MySQLCompiler_mysqldb
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except ImportError: # pragma: no cover
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raise ImportError('aiomysql.sa requires sqlalchemy')
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class MySQLCompiler_pymysql(MySQLCompiler_mysqldb):
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def construct_params(self, params=None, _group_number=None, _check=True):
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pd = super().construct_params(params, _group_number, _check)
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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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_dialect = MySQLDialect_pymysql(paramstyle='pyformat')
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_dialect.statement_compiler = MySQLCompiler_pymysql
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_dialect.default_paramstyle = 'pyformat'
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def create_engine(minsize=1, maxsize=10, loop=None,
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dialect=_dialect, pool_recycle=-1, compiled_cache=None,
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**kwargs):
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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 MySQL server.
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"""
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deprecated_cursor_classes = [
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DeserializationCursor, DictCursor, SSCursor, SSDictCursor,
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]
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cursorclass = kwargs.get('cursorclass', Cursor)
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if not issubclass(cursorclass, Cursor) or any(
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issubclass(cursorclass, cursor_class)
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for cursor_class in deprecated_cursor_classes
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):
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raise ArgumentError('SQLAlchemy engine does not support '
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'this cursor class')
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coro = _create_engine(minsize=minsize, maxsize=maxsize, loop=loop,
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dialect=dialect, pool_recycle=pool_recycle,
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compiled_cache=compiled_cache, **kwargs)
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return _EngineContextManager(coro)
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async def _create_engine(minsize=1, maxsize=10, loop=None,
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dialect=_dialect, pool_recycle=-1,
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compiled_cache=None, **kwargs):
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if loop is None:
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loop = asyncio.get_event_loop()
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pool = await aiomysql.create_pool(minsize=minsize, maxsize=maxsize,
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loop=loop,
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pool_recycle=pool_recycle, **kwargs)
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conn = await pool.acquire()
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try:
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return Engine(dialect, pool, compiled_cache=compiled_cache, **kwargs)
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finally:
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pool.release(conn)
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class Engine:
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"""Connects a aiomysql.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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def __init__(self, dialect, pool, compiled_cache=None, **kwargs):
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self._dialect = dialect
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self._pool = pool
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self._compiled_cache = compiled_cache
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self._conn_kw = kwargs
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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 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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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 _EngineAcquireContextManager(coro, self)
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async def _acquire(self):
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raw = await self._pool.acquire()
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conn = SAConnection(raw, self, compiled_cache=self._compiled_cache)
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return conn
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def release(self, conn):
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"""Revert back connection to pool."""
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if conn.in_transaction:
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raise InvalidRequestError("Cannot release a connection with "
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"not finished transaction")
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raw = conn.connection
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return self._pool.release(raw)
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def __enter__(self):
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raise RuntimeError(
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'"yield from" should be used as context manager expression')
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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 __iter__(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 (yield from 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 = yield from 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()
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return _ConnectionContextManager(self, conn)
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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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_EngineContextManager = _PoolContextManager
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_EngineAcquireContextManager = _PoolAcquireContextManager
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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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with (yield from engine) as conn:
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cur = yield from 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__ = ('_engine', '_conn')
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def __init__(self, engine, conn):
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self._engine = engine
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self._conn = conn
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def __enter__(self):
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assert self._conn is not None
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return self._conn
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def __exit__(self, *args):
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try:
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self._engine.release(self._conn)
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finally:
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self._engine = None
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self._conn = None
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