Source Code for Module Products.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  from Exceptions import MySQLConnectionError 
 14   
 15  import time 
 16  import DateTime 
 17   
 18  from Products.ZenUtils import Time as timeutils 
 19  from Queue import Queue, Empty, Full 
 20   
 21  import logging 
 22  log = logging.getLogger("zen.DbConnectionPool") 
 23   
 24  POOL_SIZE = 5 
 25  KEEP_ALIVE = 28800 
 26   
 27   
 28 -def timestamp_conv(s): 
 29      #timestamps from mysql are passed in as iso dates in the server's timezone 
 30      #but do not contain timezone information.  Convert iso time to a timestamp 
 31      #using the system timezone. We need to do this because the Zope DateTime 
 32      #will use GMT+0 when converting iso times that do not contain tz info. 
 33      timestamp = timeutils.isoToTimestamp(s) 
 34      return DateTime.DateTime(timestamp) 
 35   
 36 -class DbConnectionPool: 
 37   
 38 -    def __new__(self):                  # self is a type 
 39          if not '_the_instance' in self.__dict__: 
 40              self._the_instance = object.__new__(self) 
 41          return self._the_instance 
 42           
 43      ''' 
 44      instance = None 
 45      def __new__(cls, *args, **kargs):  
 46          if cls.instance is None: 
 47              cls.instance = object.__new__(cls, *args, **kargs) 
 48          log.debug('Returning single instance of DbConnectionPool') 
 49          return cls.instance 
 50      ''' 
 51           
 52 -    def __init__(self): 
 53          self.q = Queue(POOL_SIZE) 
 54   
 55 -    def qsize(self): 
 56          return self.q.qsize() 
 57   
 58 -    def get(self, host=None, port=None, username=None,  
 59              password=None, database=None, block=0): 
 60          try: 
 61              putstamp,obj = self.q.get(block) 
 62   
 63              if time.time() - putstamp >= KEEP_ALIVE: 
 64                  log.debug('Retrieved a stale connection; Pool size: %s' % self.qsize()) 
 65                  obj.close() 
 66                  return self._createConnection(host=host, port=port,  
 67                                              username=username,  
 68                                              password=password, 
 69                                              database=database) 
 70              else: 
 71                  log.debug('Retrieved a connection; Pool size: %s' % self.qsize()) 
 72                  if hasattr(obj, 'ping'): 
 73                      # maybe the connection timed out: reconnect if necessary 
 74                      obj.ping() 
 75                  return obj 
 76   
 77          except Empty: 
 78              return self._createConnection(host=host, port=port,  
 79                                          username=username,  
 80                                          password=password, 
 81                                          database=database) 
 82   
 83 -    def put(self, obj, block=0): 
 84          try: 
 85              self.q.put((time.time(),obj), block) 
 86              log.debug('Returned a connection; Pool size: %s' % self.qsize()) 
 87          except Full: 
 88              pass 
 89   
 90 -    def _createConnection(self, host=None, port=None,  
 91                          username=None, password=None, database=None): 
 92          # These MySQLdb imports were moved from the top of the file to 
 93          # here to avoid importing MySQLdb libs at startup.  This is 
 94          # desirable for DistributedCollector where we are usually 
 95          # executing on a remote box that may not have mysql libs around. 
 96          import MySQLdb 
 97          import MySQLdb.converters 
 98          from MySQLdb.constants import FIELD_TYPE 
 99          log.debug('Creating a new connection; Pool size: %s' % self.qsize()) 
100          conn = None 
101          mysqlconv = MySQLdb.converters.conversions.copy() 
102          mysqlconv[FIELD_TYPE.DATETIME] = DateTime.DateTime 
103          mysqlconv[FIELD_TYPE.TIMESTAMP] = timestamp_conv 
104          # FIXME for some reason it thinks my int is a long -EAD 
105          mysqlconv[FIELD_TYPE.LONG] = int 
106          if not host: 
107              host, database = database, 'events' 
108          if port: 
109              port = int(port) 
110          try: 
111              conn = MySQLdb.connect(host=host, user=username, 
112                                     port=port, passwd=password,  
113                                     db=database, conv=mysqlconv, reconnect=1) 
114              conn.autocommit(1) 
115              return conn 
116          except Exception, e: 
117              raise MySQLConnectionError(str(e)) 
118