102 lines
2.9 KiB
Python
102 lines
2.9 KiB
Python
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#!/usr/bin/env python
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# -*- mode: python; indent-tabs-mode: nil; -*- coding: utf-8 -*-
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"""
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ConnectionPool.py
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Copyright 2010 by Marcello Perathoner
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Distributable under the GNU General Public License Version 3 or newer.
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"""
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from __future__ import unicode_literals
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import logging
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import psycopg2
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import sqlalchemy.pool as pool
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import cherrypy
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from cherrypy.process import plugins
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class ConnectionCreator ():
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""" Creates connections for the connection pool. """
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def __init__ (self, params):
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self.params = params
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def __call__ (self):
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cherrypy.log (
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"Connecting to database '%(database)s' on '%(host)s:%(port)d' as user '%(user)s'."
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% self.params, context = 'POSTGRES', severity = logging.INFO)
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conn = psycopg2.connect (**self.params)
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conn.cursor ().execute ('SET statement_timeout = 5000')
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return conn
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class ConnectionPool (plugins.SimplePlugin):
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"""A WSPBus plugin that controls a SQLAlchemy engine/connection pool."""
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def __init__ (self, bus, params = None):
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plugins.SimplePlugin.__init__ (self, bus)
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self.params = params
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self.name = 'sqlalchemy'
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self.pool = None
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def _start (self):
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""" Init the connection pool. """
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pool_size = cherrypy.config.get ('sqlalchemy.pool_size', 5)
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max_overflow = cherrypy.config.get ('sqlalchemy.max_overflow', 10)
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timeout = cherrypy.config.get ('sqlalchemy.timeout', 30)
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recycle = cherrypy.config.get ('sqlalchemy.recycle', 3600)
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self.bus.log ("... pool_size = %d, max_overflow = %d" % (pool_size, max_overflow))
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return pool.QueuePool (ConnectionCreator (self.params),
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pool_size = pool_size,
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max_overflow = max_overflow,
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timeout = timeout,
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recycle = recycle,
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use_threadlocal = True)
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def connect (self):
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""" Return a connection. """
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return self.pool.connect ()
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def start (self):
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""" Called on engine start. """
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if self.pool is None:
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self.bus.log ("Creating the SQL connection pool ...")
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self.pool = self._start ()
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else:
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self.bus.log ("An SQL connection pool already exists.")
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# start.priority = 80
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def stop (self):
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""" Called on engine stop. """
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if self.pool is not None:
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self.bus.log ("Disposing the SQL connection pool.")
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self.pool.dispose ()
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self.pool = None
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def graceful (self):
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""" Called on engine restart. """
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if self.pool is not None:
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self.bus.log ("Restarting the SQL connection pool ...")
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self.pool.dispose ()
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self.pool = self._start ()
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cherrypy.process.plugins.ConnectionPool = ConnectionPool
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