def __init__(self, creator, pool_size = 5, max_overflow = 10, timeout=30, **params):
Pool.__init__(self, creator, **params)
self._pool = Queue.Queue(pool_size)
self._overflow = 0 - pool_size
self._max_overflow = max_overflow
self._timeout = timeout
self._overflow_lock = self._max_overflow > -1 and threading.Lock() or None
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 __init__(self, creator, pool_size=5, max_overflow=10, timeout=30,
**kw):
"""
Construct a QueuePool.
:param creator: a callable function that returns a DB-API
connection object. The function will be called with
parameters.
:param pool_size: The size of the pool to be maintained,
defaults to 5. This is the largest number of connections that
will be kept persistently in the pool. Note that the pool
begins with no connections; once this number of connections
is requested, that number of connections will remain.
``pool_size`` can be set to 0 to indicate no size limit; to
disable pooling, use a :class:`~sqlalchemy.pool.NullPool`
instead.
:param max_overflow: The maximum overflow size of the
pool. When the number of checked-out connections reaches the
size set in pool_size, additional connections will be
returned up to this limit. When those additional connections
are returned to the pool, they are disconnected and
discarded. It follows then that the total number of
simultaneous connections the pool will allow is pool_size +
`max_overflow`, and the total number of "sleeping"
connections the pool will allow is pool_size. `max_overflow`
can be set to -1 to indicate no overflow limit; no limit
will be placed on the total number of concurrent
connections. Defaults to 10.
:param timeout: The number of seconds to wait before giving up
on returning a connection. Defaults to 30.
:param recycle: If set to non -1, number of seconds between
connection recycling, which means upon checkout, if this
timeout is surpassed the connection will be closed and
replaced with a newly opened connection. Defaults to -1.
:param echo: If True, connections being pulled and retrieved
from the pool will be logged to the standard output, as well
as pool sizing information. Echoing can also be achieved by
enabling logging for the "sqlalchemy.pool"
namespace. Defaults to False.
:param use_threadlocal: If set to True, repeated calls to
:meth:`connect` within the same application thread will be
guaranteed to return the same connection object, if one has
already been retrieved from the pool and has not been
returned yet. Offers a slight performance advantage at the
cost of individual transactions by default. The
:meth:`unique_connection` method is provided to bypass the
threadlocal behavior installed into :meth:`connect`.
:param reset_on_return: Determine steps to take on
connections as they are returned to the pool.
reset_on_return can have any of these values:
* 'rollback' - call rollback() on the connection,
to release locks and transaction resources.
This is the default value. The vast majority
of use cases should leave this value set.
* True - same as 'rollback', this is here for
backwards compatibility.
* 'commit' - call commit() on the connection,
to release locks and transaction resources.
A commit here may be desirable for databases that
cache query plans if a commit is emitted,
such as Microsoft SQL Server. However, this
value is more dangerous than 'rollback' because
any data changes present on the transaction
are committed unconditionally.
* None - don't do anything on the connection.
This setting should only be made on a database
that has no transaction support at all,
namely MySQL MyISAM. By not doing anything,
performance can be improved. This
setting should **never be selected** for a
database that supports transactions,
as it will lead to deadlocks and stale
state.
* False - same as None, this is here for
backwards compatibility.
.. versionchanged:: 0.7.6
``reset_on_return`` accepts values.
:param listeners: A list of
:class:`~sqlalchemy.interfaces.PoolListener`-like objects or
dictionaries of callables that receive events when DB-API
connections are created, checked out and checked in to the
pool.
"""
Pool.__init__(self, creator, **kw)
self._pool = sqla_queue.Queue(pool_size)
self._overflow = 0 - pool_size
self._max_overflow = max_overflow
self._timeout = timeout
self._overflow_lock = self._max_overflow > -1 and \
threading.Lock() or DummyLock()
def __init__(self,
creator,
pool_size=5,
max_overflow=10,
timeout=30,
**kw):
"""
Construct a QueuePool.
:param creator: a callable function that returns a DB-API
connection object. The function will be called with
parameters.
:param pool_size: The size of the pool to be maintained,
defaults to 5. This is the largest number of connections that
will be kept persistently in the pool. Note that the pool
begins with no connections; once this number of connections
is requested, that number of connections will remain.
``pool_size`` can be set to 0 to indicate no size limit; to
disable pooling, use a :class:`~sqlalchemy.pool.NullPool`
instead.
:param max_overflow: The maximum overflow size of the
pool. When the number of checked-out connections reaches the
size set in pool_size, additional connections will be
returned up to this limit. When those additional connections
are returned to the pool, they are disconnected and
discarded. It follows then that the total number of
simultaneous connections the pool will allow is pool_size +
`max_overflow`, and the total number of "sleeping"
connections the pool will allow is pool_size. `max_overflow`
can be set to -1 to indicate no overflow limit; no limit
will be placed on the total number of concurrent
connections. Defaults to 10.
:param timeout: The number of seconds to wait before giving up
on returning a connection. Defaults to 30.
:param recycle: If set to non -1, number of seconds between
connection recycling, which means upon checkout, if this
timeout is surpassed the connection will be closed and
replaced with a newly opened connection. Defaults to -1.
:param echo: If True, connections being pulled and retrieved
from the pool will be logged to the standard output, as well
as pool sizing information. Echoing can also be achieved by
enabling logging for the "sqlalchemy.pool"
namespace. Defaults to False.
:param use_threadlocal: If set to True, repeated calls to
:meth:`connect` within the same application thread will be
guaranteed to return the same connection object, if one has
already been retrieved from the pool and has not been
returned yet. Offers a slight performance advantage at the
cost of individual transactions by default. The
:meth:`unique_connection` method is provided to bypass the
threadlocal behavior installed into :meth:`connect`.
:param reset_on_return: If true, reset the database state of
connections returned to the pool. This is typically a
ROLLBACK to release locks and transaction resources.
Disable at your own peril. Defaults to True.
:param listeners: A list of
:class:`~sqlalchemy.interfaces.PoolListener`-like objects or
dictionaries of callables that receive events when DB-API
connections are created, checked out and checked in to the
pool.
"""
Pool.__init__(self, creator, **kw)
self._pool = sqla_queue.Queue(pool_size)
self._overflow = 0 - pool_size
self._max_overflow = max_overflow
self._timeout = timeout
self._overflow_lock = self._max_overflow > -1 and \
threading.Lock() or None
