150 lines
4.2 KiB
Python
150 lines
4.2 KiB
Python
# sqlalchemy/pool/dbapi_proxy.py
|
|
# Copyright (C) 2005-2019 the SQLAlchemy authors and contributors
|
|
# <see AUTHORS file>
|
|
#
|
|
# This module is part of SQLAlchemy and is released under
|
|
# the MIT License: http://www.opensource.org/licenses/mit-license.php
|
|
|
|
|
|
"""DBAPI proxy utility.
|
|
|
|
Provides transparent connection pooling on top of a Python DBAPI.
|
|
|
|
This is legacy SQLAlchemy functionality that is not typically used
|
|
today.
|
|
|
|
"""
|
|
|
|
from .impl import QueuePool
|
|
from .. import util
|
|
from ..util import threading
|
|
|
|
proxies = {}
|
|
|
|
|
|
@util.deprecated(
|
|
"1.3",
|
|
"The :func:`.pool.manage` function is deprecated, and will be "
|
|
"removed in a future release.",
|
|
)
|
|
def manage(module, **params):
|
|
r"""Return a proxy for a DB-API module that automatically
|
|
pools connections.
|
|
|
|
Given a DB-API 2.0 module and pool management parameters, returns
|
|
a proxy for the module that will automatically pool connections,
|
|
creating new connection pools for each distinct set of connection
|
|
arguments sent to the decorated module's connect() function.
|
|
|
|
:param module: a DB-API 2.0 database module
|
|
|
|
:param poolclass: the class used by the pool module to provide
|
|
pooling. Defaults to :class:`.QueuePool`.
|
|
|
|
:param \**params: will be passed through to *poolclass*
|
|
|
|
"""
|
|
try:
|
|
return proxies[module]
|
|
except KeyError:
|
|
return proxies.setdefault(module, _DBProxy(module, **params))
|
|
|
|
|
|
def clear_managers():
|
|
"""Remove all current DB-API 2.0 managers.
|
|
|
|
All pools and connections are disposed.
|
|
"""
|
|
|
|
for manager in proxies.values():
|
|
manager.close()
|
|
proxies.clear()
|
|
|
|
|
|
class _DBProxy(object):
|
|
|
|
"""Layers connection pooling behavior on top of a standard DB-API module.
|
|
|
|
Proxies a DB-API 2.0 connect() call to a connection pool keyed to the
|
|
specific connect parameters. Other functions and attributes are delegated
|
|
to the underlying DB-API module.
|
|
"""
|
|
|
|
def __init__(self, module, poolclass=QueuePool, **kw):
|
|
"""Initializes a new proxy.
|
|
|
|
module
|
|
a DB-API 2.0 module
|
|
|
|
poolclass
|
|
a Pool class, defaulting to QueuePool
|
|
|
|
Other parameters are sent to the Pool object's constructor.
|
|
|
|
"""
|
|
|
|
self.module = module
|
|
self.kw = kw
|
|
self.poolclass = poolclass
|
|
self.pools = {}
|
|
self._create_pool_mutex = threading.Lock()
|
|
|
|
def close(self):
|
|
for key in list(self.pools):
|
|
del self.pools[key]
|
|
|
|
def __del__(self):
|
|
self.close()
|
|
|
|
def __getattr__(self, key):
|
|
return getattr(self.module, key)
|
|
|
|
def get_pool(self, *args, **kw):
|
|
key = self._serialize(*args, **kw)
|
|
try:
|
|
return self.pools[key]
|
|
except KeyError:
|
|
self._create_pool_mutex.acquire()
|
|
try:
|
|
if key not in self.pools:
|
|
kw.pop("sa_pool_key", None)
|
|
pool = self.poolclass(
|
|
lambda: self.module.connect(*args, **kw), **self.kw
|
|
)
|
|
self.pools[key] = pool
|
|
return pool
|
|
else:
|
|
return self.pools[key]
|
|
finally:
|
|
self._create_pool_mutex.release()
|
|
|
|
def connect(self, *args, **kw):
|
|
"""Activate a connection to the database.
|
|
|
|
Connect to the database using this DBProxy's module and the given
|
|
connect arguments. If the arguments match an existing pool, the
|
|
connection will be returned from the pool's current thread-local
|
|
connection instance, or if there is no thread-local connection
|
|
instance it will be checked out from the set of pooled connections.
|
|
|
|
If the pool has no available connections and allows new connections
|
|
to be created, a new database connection will be made.
|
|
|
|
"""
|
|
|
|
return self.get_pool(*args, **kw).connect()
|
|
|
|
def dispose(self, *args, **kw):
|
|
"""Dispose the pool referenced by the given connect arguments."""
|
|
|
|
key = self._serialize(*args, **kw)
|
|
try:
|
|
del self.pools[key]
|
|
except KeyError:
|
|
pass
|
|
|
|
def _serialize(self, *args, **kw):
|
|
if "sa_pool_key" in kw:
|
|
return kw["sa_pool_key"]
|
|
|
|
return tuple(list(args) + [(k, kw[k]) for k in sorted(kw)])
|