Source Code for Module ZenEvents.DbConnectionPool

  1  ########################################################################### 
  2  # 
  3  # This program is part of Zenoss Core, an open source monitoring platform. 
  4  # Copyright (C) 2007, Zenoss Inc. 
  5  # 
  6  # This program is free software; you can redistribute it and/or modify it 
  7  # under the terms of the GNU General Public License version 2 as published by 
  8  # the Free Software Foundation. 
  9  # 
 10  # For complete information please visit: http://www.zenoss.com/oss/ 
 11  # 
 12  ########################################################################### 
 13  import MySQLdb 
 14  import MySQLdb.converters 
 15  from MySQLdb.constants import FIELD_TYPE 
 16   
 17  import time 
 18  import DateTime 
 19   
 20  from Queue import Queue, Empty, Full 
 21   
 22  import logging 
 23  log = logging.getLogger("zen.DbConnectionPool") 
 24   
 25  POOL_SIZE = 5 
 26  KEEP_ALIVE = 28800 
 27   
 28 -class DbConnectionPool(Queue): 
 29   
 30 -    def __new__(type): 
 31          if not '_the_instance' in type.__dict__: 
 32              type._the_instance = object.__new__(type) 
 33          return type._the_instance 
 34           
 35      ''' 
 36      instance = None 
 37      def __new__(cls, *args, **kargs):  
 38          if cls.instance is None: 
 39              cls.instance = object.__new__(cls, *args, **kargs) 
 40          log.debug('Returning single instance of DbConnectionPool') 
 41          return cls.instance 
 42      ''' 
 43           
 44 -    def __init__(self): 
 45          Queue.__init__(self, POOL_SIZE) 
 46   
 47 -    def get(self, backend=None, host=None, port=None, username=None,  
 48              password=None, database=None, block=0): 
 49          try: 
 50              putstamp,obj = Queue.get(self, block) 
 51   
 52              if time.time() - putstamp >= KEEP_ALIVE: 
 53                  log.debug('Retrieved a stale connection; Pool size: %s' % self.qsize()) 
 54                  obj.close() 
 55                  return self._createConnection(host=host, port=port,  
 56                                              username=username,  
 57                                              password=password, 
 58                                              database=database) 
 59              else: 
 60                  log.debug('Retrieved a connection; Pool size: %s' % self.qsize()) 
 61                  if hasattr(obj, 'ping'): 
 62                      # maybe the connection timed out: reconnect if necessary 
 63                      obj.ping() 
 64                  return obj 
 65   
 66          except Empty: 
 67              return self._createConnection(host=host, port=port,  
 68                                          username=username,  
 69                                          password=password, 
 70                                          database=database) 
 71   
 72 -    def put(self, obj, block=0): 
 73          try: 
 74              Queue.put(self, (time.time(),obj), block) 
 75              log.debug('Returned a connection; Pool size: %s' % self.qsize()) 
 76          except Full: 
 77              pass 
 78   
 79 -    def _createConnection(self, host=None, port=None,  
 80                          username=None, password=None, database=None): 
 81          log.debug('Creating a new connection; Pool size: %s' % self.qsize()) 
 82          conn = None 
 83          """ 
 84          if self.backend == "omnibus": 
 85              import Sybase 
 86              self.conn = Sybase.connect(self.database,self.username, 
 87                                          self.password) 
 88          elif self.backend == "oracle": 
 89              import DCOracle2 
 90              connstr = "%s/%s@%s" % (self.username, self.password, self.database) 
 91              self.conn = DCOracle2.connect(connstr)                                         
 92          elif self.backend == "mysql": 
 93          """ 
 94          mysqlconv = MySQLdb.converters.conversions.copy() 
 95          mysqlconv[FIELD_TYPE.DATETIME] = DateTime.DateTime 
 96          mysqlconv[FIELD_TYPE.TIMESTAMP] = DateTime.DateTime 
 97          # FIXME for some reason it thinks my int is a long -EAD 
 98          mysqlconv[FIELD_TYPE.LONG] = int 
 99          if not host: 
100              host, database = database, 'events' 
101          conn = MySQLdb.connect(host=host, user=username, 
102                                 port=port, passwd=password,  
103                                 db=database, conv=mysqlconv, reconnect=1) 
104          conn.autocommit(1) 
105          return conn 
106