MiscUtils.DBPool | index /usr/local/share/webware/MiscUtils/DBPool.py

`DBPool.py
Implements a pool of cached connections to a database for any DB-API 2
compliant database module. This should result in a speedup for persistent
applications like Webware. The pool of connections is threadsafe regardless
of whether the used DB-API 2 general has a threadsafety of 1 or 2.
For more information on the DB API, see:
http://www.python.org/topics/database/DatabaseAPI-2.0.html
The idea behind DBPool is that it's completely seamless, so once you have
established your connection, use it just as you would any other DB-API 2
compliant module. For example:
import pgdb # import used DB-API 2 module
from MiscUtils.DBPool import DBPool
dbpool = DBPool(pgdb, 5, host=..., database=..., user=..., ...)
db = dbpool.connection()
Now use "db" exactly as if it were a pgdb connection. It's really
just a proxy class.
db.close() will return the connection to the pool, not actually
close it. This is so your existing code works nicely.
DBPool is actually intended to be a demonstration of concept not to be
used in a productive environment. It is really a very simple solution with
several drawbacks. For instance, pooled database connections which have
become invalid are not automatically recovered. For a more sophisticated
solution, please have a look at the DBUtils package:
http://www.webwareforpython.org/DBUtils
CREDIT
* Contributed by Dan Green.
* Thread safety bug found by Tom Schwaller.
* Fixes by Geoff Talvola (thread safety in _threadsafe_get_connection()).
* Clean up by Chuck Esterbrook.
* Fix unthreadsafe functions which were leaking, Jay Love.
* Eli Green's webware-discuss comments were lifted for additional docs.
* Coding and comment clean-up by Christoph Zwerschke.`

Classes

``

__builtin__.object
  DBPool
  PooledConnection
exceptions.Exception(exceptions.BaseException)
  DBPoolError
    NotSupportedError

class DBPool(__builtin__.object)

``

Methods defined here:

__init__(self, dbapi, maxconnections, *args, **kwargs)
  `Set up the database connection pool.
  dbapi: the DB-API 2 compliant module you want to use
  maxconnections: the number of connections cached in the pool
  args, kwargs: the parameters that shall be used to establish
  the database connections using connect()`

Data descriptors defined here:

__dict__
  `dictionary for instance variables (if defined)`

__weakref__
  `list of weak references to the object (if defined)`

class DBPoolError(exceptions.Exception)
`` | `General database pooling error.`

Method resolution order:
  DBPoolError
  exceptions.Exception
  exceptions.BaseException
  __builtin__.object

Data descriptors defined here:

__weakref__
  `list of weak references to the object (if defined)`

Methods inherited from exceptions.Exception:

__init__(...)
  `x.__init__(...) initializes x; see help(type(x)) for signature`

Data and other attributes inherited from exceptions.Exception:

__new__ = <built-in method __new__ of type object>
  `T.__new__(S, ...) -> a new object with type S, a subtype of T`

Methods inherited from exceptions.BaseException:

__delattr__(...)
  `x.__delattr__('name') <==> del x.name`

__getattribute__(...)
  `x.__getattribute__('name') <==> x.name`

__getitem__(...)
  `x.__getitem__(y) <==> x[y]`

__getslice__(...)
  `x.__getslice__(i, j) <==> x[i:j]
  Use of negative indices is not supported.`

__reduce__(...)

__repr__(...)
  `x.__repr__() <==> repr(x)`

__setattr__(...)
  `x.__setattr__('name', value) <==> x.name = value`

__setstate__(...)

__str__(...)
  `x.__str__() <==> str(x)`

__unicode__(...)

Data descriptors inherited from exceptions.BaseException:

__dict__

args

message

class NotSupportedError(DBPoolError)
`` | `Missing support from database module error.`

Method resolution order:
  NotSupportedError
  DBPoolError
  exceptions.Exception
  exceptions.BaseException
  __builtin__.object

Data descriptors inherited from DBPoolError:

__weakref__
  `list of weak references to the object (if defined)`

Methods inherited from exceptions.Exception:

__init__(...)
  `x.__init__(...) initializes x; see help(type(x)) for signature`

Data and other attributes inherited from exceptions.Exception:

__new__ = <built-in method __new__ of type object>
  `T.__new__(S, ...) -> a new object with type S, a subtype of T`

Methods inherited from exceptions.BaseException:

__delattr__(...)
  `x.__delattr__('name') <==> del x.name`

__getattribute__(...)
  `x.__getattribute__('name') <==> x.name`

__getitem__(...)
  `x.__getitem__(y) <==> x[y]`

__getslice__(...)
  `x.__getslice__(i, j) <==> x[i:j]
  Use of negative indices is not supported.`

__reduce__(...)

__repr__(...)
  `x.__repr__() <==> repr(x)`

__setattr__(...)
  `x.__setattr__('name', value) <==> x.name = value`

__setstate__(...)

__str__(...)
  `x.__str__() <==> str(x)`

__unicode__(...)

Data descriptors inherited from exceptions.BaseException:

__dict__

args

message

class PooledConnection(__builtin__.object)
`` | `A wrapper for database connections to help with DBPool. You don't normally deal with this class directly, but use DBPool to get new connections.`

Methods defined here:

__del__(self)

__getattr__(self, name)

__init__(self, pool, con)

close(self)
  `Close the pooled connection.`

Data descriptors defined here:

__dict__
  `dictionary for instance variables (if defined)`

__weakref__
  `list of weak references to the object (if defined)`